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Research ArticleAnalysis of Stress Asymmetric Distribution Law of SurroundingRockofRoadway in InclinedCoal SeamACaseStudyofShitanjingNo 2 Coal Seam
Xianyu Xiong Jun Dai and Xinnian Chen
School of Architecture and Civil Engineering Xirsquoan University of Science and Technology Xirsquoan Shaanxi 710054 China
Correspondence should be addressed to Xianyu Xiong xiongxianyu520163com
Received 10 March 2020 Revised 4 May 2020 Accepted 9 May 2020 Published 31 May 2020
Academic Editor Yinshan Tang
Copyright copy 2020 Xianyu Xiong et alis is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited
Asymmetrical deformation and failure characteristics of the surrounding rock at the right-angled trapezoidal roadway in theShitanjing No 2 mining area has created great difficulties in the stability control and support of the roadway First numericalsimulations were applied to systematically analyze the distribution rules for vertical stress horizontal stress and failurecharacteristics of the roadway Furthermore verifications were conducted via laboratory model tests and practical engineeringapplication e results show that the two walls of the roadway the roof and the sharp corners demonstrate obvious asymmetricstress concentrationse peak value of stress concentration in the low side (right wall) is significantly greater than that in the highside (left wall) and the distances from high and low sides of roadway to both walls of the roadway are obviously different e twosharp corners which are symmetrical along the same direction of the coal seam inclination show obvious compressive stresseswhile the opposite directions show obvious tensile stress regions at both sharp corners further maximum values of thecompressive and tensile stresses appear at the two corners of the roadway roof and their magnitudes vary with the change ininclination and ground stress
1 Introduction
With the gradual exhaustion of high-quality coal resourcesand shrinkage of production in the eastern part of China inthe 21st century the focus of resource exploitation is shiftingto the western part of China e exploitation of coal re-sources plays an important role in facilitating energy effi-ciency in the western region [1ndash4] e inclined coal seamreserves in the western region of China account for ap-proximately 101 of the recoverable reserves and there arehigh-quality coal seams with high mining value [5ndash7]However in the mining process of an inclined seam thestress of the surrounding rock of the roadway is asymmetricowing to the influence of the inclination angle whichpresents great difficulty in stability control and supportengineering of the roadway [8ndash15]
Domestic and foreign researchers mainly focus onstudying the asymmetric stress distribution characteristics of
surrounding rocks in inclined seam roadways with largeinclinations and steeply inclined seams and the sectionforms are mostly rectangular and arch roadways e cur-rent research results indicate that the stress distributions inthe surrounding rocks of roadways exhibit obvious asym-metric characteristics for roadways excavated at large in-clinations [16ndash20] and for steeply inclined [21ndash26] coalseams the stress concentrations on the roof two walls andfloor of a roadway is obviously different and increases withthe inclination angle Asymmetric deformation and failureof the roadway will occur due to asymmetric stress distri-bution of the surrounding rock [27] Aiming at the asym-metric failure characteristics of the roof two walls and floorof the roadway (rectangular and arch) supporting measureswere proposed in literature [1] However there are fewstudies on the asymmetric stress distributions of sur-rounding rocks in right-angled trapezoidal roadways withgently inclined coal seams at different inclination angles
HindawiAdvances in Civil EngineeringVolume 2020 Article ID 8877172 14 pageshttpsdoiorg10115520208877172
erefore it is of great theoretical value and practical sig-nificance to conduct numerical simulations and analyze thestress asymmetry characteristics of right-angled trapezoidalroadways in gently inclined seams for stability evaluation
In the inclined coal seam the roadway is usuallyarranged along the roof middle and bottom of the coalseam e location of the roadway in the coal seam isdifferent resulting in different cross-sectional shapes ofthe roadway e Shitanjing No 2 mining area is locatedin the western high-mountain area It is a typical gentlyinclined coal seam with a dip angle of 18ndash27deg ethickness of the recoverable coal seam is 55ndash606 m eroadway is excavated along the roof of the coal seam toform a right-angled trapezoidal roadway Taking theShitanjing No 2 mining area as the engineering back-ground theoretical analysis and numerical modelingwith FLAC3D software are used to study the asymmetricdistribution of surrounding rock stress in a right-angledtrapezoidal roadway with an inclined dip angle Based onthe engineering background of the Shitanjing No 2mining area in this research the asymmetric stressdistribution law of the surrounding rock of the right-angled trapezoidal roadway in different inclined seams isevaluated by theoretical analysis and numerical simu-lations using FLAC3D and verified via laboratory modeltests and practical engineering application which pro-vide the scientific basis for the selection of supportingschemes for the right-angled trapezoidal roadway in thisarea
2 Analysis of Asymmetric Characteristics of theStress in the Surrounding Rocks ofthe Roadway
Numerous scholars have discovered that after the exca-vation of an inclined coal seam roadway the stress re-distribution around the roadway exhibits obviousasymmetric characteristics and the stress distributionbetween the two walls of the roadway and the roof and flooris obviously different under the action of the overlyingstrata load [28ndash30] As can be observed from Figure 1 thestress acting on the roadway is characterized by the shearstress σx along the inclined direction of the coal seam andthe compressive stress σy perpendicular to the coal seamowing to the influence of the dip angle of the seame highside is subjected to a tensile force σx parallel to the directionof the coal body while the low side is subjected to asqueezing force σy (Figure 1)
is asymmetry and nonhomogeneous stress statelead to stress concentration peak value on the right wall(low side) being greater than that on the left wall (highside) and the distances from the points with the peakstress concentrations at the high and low sides to bothwalls of the roadway are different (Figure 2) Accordingto the formula for the width of the stress limit equilib-rium zone the distance between the stress concentrationareas A and B and the wall of the roadway can be cal-culated as xA and xB respectively as shown in equations(1) and (2)
xA mAf
2tgφ0ln
kAch + c0tgφ0( 1113857
c0tgφ0( 1113857 + Pxf( 11138571113888 1113889 (1)
xB mBf
2tgφ0ln
kBch + c0tgφ0( 1113857
c0tgφ0( 1113857 + Pxf( 11138571113888 1113889 (2)
where xA and xB are the widths of the stress limitequilibrium zone (m) mA and mB denote the height of theroadway (m) f is the lateral pressure coefficient φ0 is thefriction angle of composite coal rock (deg) kA and kB denote thepressure rise coefficients h is the coal mining depth (m) c0 isthe cohesive force between the coal seam and roof rockstratum (MPa) c is the bulk density (kgmiddotm3) and Px is thesupport resistance to coal support (MPa)
It can be seen from equations (1) and (2) that the dis-tances from the stress concentration areas A and B to the twowalls play a key role in determining the heights of the twowalls of the roadway For the right-angled trapezoidalroadway in the inclined coal seam the distance from thestress concentration area of the high side to the wall of theroadway is larger than that of the low side because of theobvious difference between the heights of the high and lowsides
Roadway
σx
σx
σy
σy
τ
τ
High side
Low side
Figure 1 Stress decomposition map of the surrounding rock oftwo laneways
xA
xB
kAγH
kBγHγH
γH
xA gt xBkAγH lt kBγH
RoadwayA
B
Stressconcentration
locationStress
concentrationlocation
High side
Low side
Figure 2 Stress distribution map of the surrounding rock of twolaneways
2 Advances in Civil Engineering
For the roof of the roadway the stress distribution alsoexhibits obvious asymmetric characteristics that is thestress concentration of the right wall (low side) sharp angleof the roadway roof is greater than the left wall (high side)sharp angle and it changes with the change in inclination asshown in Figure 3 ese values are calculated as follows
σwL 11139465b1
05ab1c1h1dh
σwR 11139466b1minusb2
05a 6b1 minus b2( 1113857c1h1dh
(3)
where σwL and σwR are the stresses at the corners of the highand low sides of the roadway roof (MPa) respectively a isthe width of the roadway (m) c1 is the average rock bulkdensity (kgmiddotm3) h1 is the coal mining depth (m) b1 and b2are the heights of the roadway in the high and low sides (m)respectively
In conclusion under the asymmetric stress of the sur-rounding rock of the right angle trapezoid roadway in theinclined coal seam the deformation and failure of thesurrounding rock of roadway also presents obvious asym-metric characteristics e two walls of the roadway aresqueezed and dislocated on the inside and bulge out con-siderably e damage on the low side is greater than that inthe high side and the greatest damage is observed in the twocorners of the low side
3 Model Establishment andParameter Selection
Based on the Mohr Coulomb criterion a numerical model isestablished using the numerical simulation softwareFLAC3D (Figure 4) emodel size is 36mtimes 5mtimes 36m thefour walls are constrained in the normal direction the topsurface is the ground surface and the surface is the freeboundary of stress and displacement the bottom boundaryis subjected to horizontal and vertical constraints and thetop of the model is the overlying rock layer Four typicalcalculation models with inclination angles of 18deg 21deg 24degand 27deg were established and stresses of 25MPa 5MPa10MPa 15MPa and 20MPa were applied e asymmetricdistribution characteristics of surrounding rock stress in theright-angled trapezoidal roadway were analyzed Accordingto the coal seam geological conditions of the Shitanjing No 2mining area the physical and mechanical parameters of thesurrounding rock are selected as given in Table 1
4 Numerical Simulation Analysis
41 Vertical Stress Distribution Characteristics of RoadwayFigure 5 shows the vertical stress nephogram of the right-angled roadway in different inclined seams under a simu-lated ground stress of 25MPa It can be seen from the figurethat the stress concentration on the right wall (low side) ofthe roadway is greater than that on the left wall (high side)e distance from the stress concentration area of the leftwall (high side) to the side of the roadway is greater than thatof the right wall (low side) e stress concentration on the
roof of the roadway deviates toward the life wall (high side)and the stress concentration on the floor deviates toward theright wall (low side) and changes with the inclination angle
Figure 6 is the curve of the stress concentration peakvalue of the right-angled trapezoidal roadway for differentinclined seams with simulated ground stress q Figure 6displays that the stress concentration peak values of bothwalls of the roadway increases with the increase in incli-nation and ground stress When the inclination angle is18ndash27deg the stress concentration peak value of the low side is107ndash133 times greater than that of the high side Howeverunder the action of small ground stress the difference inpeak stress between the two walls is not very obvious mainlybecause of the influence of the dip angle
Figure 7 is the curve of the distance from the peak stressconcentration to both the walls of the right-angled trape-zoidal roadway in the inclined coal seam with differentground stresses e distances from the points at which thepeak values of stress concentration occur on the two walls ofthe roadway to the sides of the roadway are obviouslydifferent and increase with the increase in inclination andground stress as shown in Figure 7 and Table 2 When theinclination is 18ndash27deg and the ground stress is 10MPa at thehigh side of the roadway the stress concentration peak to thedistance of the side wall of the roadway is 128ndash300mmgreater than that at the low side When the ground stress is10ndash20MPa and the inclination is 18deg at the high side of theroadway the stress concentration peak to the side wall of theroadway is greater than that at the low side which is126ndash136mm However with the increase in inclinationangle the distances from the points with peak stress con-centrations at the two sides to the walls of the roadwaybecome progressively smaller
42 Horizontal Stress Distribution Characteristics of theRoadway Figure 8 shows the horizontal stress nephogramof the right-angled trapezoidal roadway in different inclinedseams under a simulated ground stress of 25MPa It can beseen from Figure 8 that the two cusps symmetrical with thedip angle of the coal seam show an obvious compressivestress zone while the opposite direction shows an obvioustensile stress zone and the maximum values of the com-pressive and tensile stresses appear at the two cusps of theroof of the roadway With the increase in inclination anglethe stress concentration at the corner of the roadwaydecreases
a
b2
b1
Roadway
High side
Low side
Figure 3 Stress distribution at the roof of the laneway
Advances in Civil Engineering 3
Table 1 Numerical simulation of physical and mechanical parameters of coal and rock
Rock stratum ickness(m)
Density(kgmiddotmminus3)
Bulk modulus(GPa)
Shear modulus(GPa)
Friction(deg)
Cohesion(MPa)
Tension(MPa)
(1) Siltstone 46 2 460 849 647 321 57 377(2) Medium grainsandstone 4 2 510 1011 727 370 118 278
(3) Mudstone 29 2 530 779 534 315 185 154(4) Coal seam 55 1 400 180 083 210 160 050(5) Siltstone 92 2 460 849 647 321 57 377
Stress (Pa)ndash48069E + 05ndash50000E + 05ndash75000E + 05ndash10000E + 06ndash12500E + 06ndash15000E + 06ndash17500E + 06ndash20000E + 06ndash22500E + 06ndash25000E + 06ndash27500E + 06ndash30000E + 06ndash32500E + 06ndash35000E + 06ndash37500E + 06ndash40000E + 06ndash42500E + 06ndash43232E + 06
(a)
Stress (Pa)99217E + 0400000E + 00ndash25000E + 05ndash50000E + 05ndash75000E + 05ndash10000E + 06ndash12500E + 06ndash15000E + 06ndash17500E + 06ndash20000E + 06ndash22500E + 06ndash25000E + 06ndash27500E + 06ndash30000E + 06ndash32500E + 06ndash35000E + 06
ndash42500E + 06ndash45000E + 06ndash45879E + 06
ndash37500E + 06ndash40000E + 06
(b)
Stress (Pa)ndash12397E + 06ndash12500E + 06ndash15000E + 06ndash17500E + 06ndash20000E + 06ndash22500E + 06ndash25000E + 06ndash27500E + 06ndash30000E + 06ndash32500E + 06ndash35000E + 06ndash37500E + 06ndash40000E + 06ndash40781E + 06
(c)
Stress (Pa)ndash17537E + 06ndash18000E + 06ndash20000E + 06ndash22000E + 06ndash24000E + 06ndash26000E + 06ndash28000E + 06ndash30000E + 06ndash32000E + 06
ndash38000E + 06ndash40000E + 06ndash40627E + 06
ndash34000E + 06ndash36000E + 06
(d)
Figure 5 Vertical stress nephogram of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
36m
3m
36m
5m
45m
18deg21deg24deg27deg
SiltstoneMedium grain sandstoneMudstoneCoal seam
Siltstone
Roadway
Figure 4 Numerical calculation model
4 Advances in Civil Engineering
0 3 6 9 12 15 18 21 240
5
10
15
20
25
30
35
40
High sideLow side
Stre
ss (M
Pa)
q (MPa)
(a)
High sideLow side
q (MPa)0 3 6 9 12 15 18 21 24
0
5
10
15
20
25
30
35
40
45
Stre
ss (M
Pa)
(b)
High sideLow side
q (MPa)0 3 6 9 12 15 18 21 24
0
5
10
15
20
25
30
35
40
Stre
ss (M
Pa)
(c)
High sideLow side
q (MPa)0 3 6 9 12 15 18 21 24
0
5
10
15
20
25
30
35
40
Stre
ss (M
Pa)
(d)
Figure 6 Comparative analysis curves of peak stress and ground stress of the two sides of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
15 18 21 24 27 300
3
6
9
12
Dip angle (deg)
High sideLow side
Dist
ance
(m)
(a)
Dip angle (deg)
High sideLow side
Dist
ance
(m)
15 18 21 24 27 303
6
9
12
15
(b)
Figure 7 Curve of the change in stress concentration peak with the side distance of the two sides of the roadway with inclination angle (a)10MPa (b) 20MPa
Advances in Civil Engineering 5
43 Horizontal Displacement Characteristics of the RoadwayFigures 9 and 10 depict the horizontal stress nephogram ofthe roadway and the displacement analysis diagram of thetwo walls of the roadway with different simulated groundstresses q and different inclination angles respectivelyFigures 9 and 10 and Table 3 reveal that the displacementdifference between the two walls of the roadway is obviousand increases with the increase in group stress e groupstress is 10ndash15MPa and the inclination angle is 18deg and theroadwayrsquos high side is 15ndash77mm larger than the low sideHowever the difference decreases with the increase in in-clination angle When the inclination angle is 18ndash27deg and thegroup stress is 10MPa the roadwayrsquos high side is 15ndash10mm
larger than the low side e main reason is that the dif-ference in height between the two walls leads to unevenstress distribution
5 Validation of the Simulation Test
51 Test Plan To verify the asymmetric stress distributioncharacteristics of the surrounding rock of the right-angledtrapezoidal roadway in the inclined seam further the lab-oratory model test adopted the principle of geometricsimilarity and strength equality and established four types ofright-angled trapezoidal roadway test models with differentinclined seam angles namely 18deg 21deg 24deg and 27deg
Table 2 Distance from peak stress concentration to both sides of roadway (mm)
Dip angleGround stress 10MPa Ground stress 20MPa
Low side High side Low side High side18deg 642 514 1203 106721deg 605 405 1185 98524deg 54 29 1118 83827deg 501 201 1055 665
70522E + 0570000E + 0560000E + 0550000E + 0540000E + 0530000E + 0520000E + 0510000E + 0500000E + 00ndash10000E + 05ndash20000E + 05ndash30000E + 05ndash40000E + 05ndash50000E + 05ndash60000E + 05ndash70000E + 05ndash80000E + 05ndash90000E + 05ndash90594E + 05
Stress (Pa)
(a)
94567E + 0580000E + 0560000E + 0540000E + 0520000E + 0500000E + 00ndash20000E + 05ndash40000E + 05ndash60000E + 05ndash80000E + 05ndash10000E + 06ndash11309E + 06
Stress (Pa)
(b)
ndash10000E + 05ndash20000E + 05ndash30000E + 05ndash40000E + 05ndash50000E + 05ndash60000E + 05ndash70000E + 05ndash76621E + 05
39580E + 0530000E + 0520000E + 0510000E + 0500000E + 00
Stress (Pa)
(c)
ndash10000E + 05ndash20000E + 05ndash30000E + 05ndash40000E + 05ndash50000E + 05ndash60000E + 05ndash64765E + 05
39675E + 0530000E + 0520000E + 0510000E + 0500000E + 00
Stress (Pa)
(d)
Figure 8 Horizontal stress distribution characteristics of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
6 Advances in Civil Engineering
Displacement (m)
ndash50000E ndash 04ndash10000E ndash 03ndash15000E ndash 03ndash20000E ndash 03ndash22092E ndash 03
35007E ndash 03
30000E ndash 0335000E ndash 03
25000E ndash 0320000E ndash 0315000E ndash 0310000E ndash 0350000E ndash 0400000E + 00
(a)
Displacement (m)
ndash25000E ndash 04ndash50000E ndash 04ndash75000E ndash 04ndash10000E ndash 03ndash12500E ndash 03ndash12767E ndash 03
20000E ndash 0321873E ndash 03
15000E ndash 0317500E ndash 03
12500E ndash 0310000E ndash 0375000E ndash 0450000E ndash 0425000E ndash 0400000E + 00
(b)
Displacement (m)
ndash25000E ndash 04ndash50000E ndash 04ndash75000E ndash 04ndash10000E ndash 03ndash12500E ndash 03ndash15000E ndash 03ndash17500E ndash 03ndash18776E ndash 03
20000E ndash 03
15000E ndash 0317500E ndash 03
12500E ndash 0310000E ndash 03
26609E ndash 0325000E ndash 0322500E ndash 03
75000E ndash 0450000E ndash 0425000E ndash 0400000E + 00
(c)
Displacement (m)
ndash25000E ndash 04ndash50000E ndash 04ndash75000E ndash 04ndash10000E ndash 03ndash10040E ndash 03
15000E ndash 0316911E ndash 03
12500E ndash 0310000E ndash 0375000E ndash 0450000E ndash 0425000E ndash 0400000E + 00
(d)
Figure 9 Horizontal stress distribution characteristics of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
0 3 6 9 12 15 18 21 240
30
60
90
120
150
180
210
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)
(a)
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)0 3 6 9 12 15 18 21 24
0
30
60
90
120
150
180
(b)
Figure 10 Continued
Advances in Civil Engineering 7
(Figure 11)e geometric similarity ratio is 1 30 the modelsize is 72 cmtimes 72 cmtimes 10 cm and the lithology parametersare selected from the engineering background of the Shi-tanjing No 2 mining area which is the same as that for thenumerical simulation Different proportions of cementmortar were used to simulate the characteristics
e measurement points are arranged at the roadwaywalls roof and floor as well as the corners A verticaluniform load is applied to the model in a stepwise manneruntil the specimen is completely destroyede strain valuesof each measurement point under different loads arerecorded in real time during the loading process
52 Analysis of Test Results
521 Stress Distribution Law of the Roof Surrounding theRock Figure 12 displays a simulated ground stress-straincurve of the roof surrounding the rock of the trapezoidalroadway with different dip angles e stress of the roofsurrounding the rock of the roadway presents obviousasymmetric characteristics and the size distribution of themiddle measuring point of the roof (Intermediate)gt the lowside measuring point of the roof (R- low side)gt the high sidemeasuring point of the roof (R- high side) from Figure 12 Inaddition the maximum strain on the low side of the sur-rounding rock is significantly larger than that on the highside e greater the dip angle the more obvious the dif-ference in stress distribution between the high and low sides
of the surrounding rock of the roadway When the incli-nation angle is in the range of 18degndash27deg the maximum strainon the right wall of the roof (R- low side) is 13ndash21 timeslarger than that on the left wall of the roof (R- high side)
522 Stress Distribution Law of the Surrounding Rocks of theTwo Walls of the Roadway Figure 13 describes the simu-lated ground stress-strain curve of the surrounding rock ofthe right-angled trapezoidal roadway with different dipangles It can be concluded that the stress concentrations onthe two walls of the roadway are clearly different and theyincrease with increasing inclination and ground stress einclination angle is 18degndash27deg and the maximum value of theright wall (low side) stress concentration is 12ndash17 times thatof the left wall (high side)
523 Stress Distribution Law of the Two Surrounding RocksFigure 14 is a simulated ground stress-strain curve of thesurrounding rock at the corners of a right-angled trapezoidalroadway with different dip angles Figure 14 reveals that thestress distribution of each point at the four corners of theroadway is different From large to small the order is lowside shoulder angle (LSSA) high side shoulder angle(HSSA) low side bottom angle (LSBA) and high sidebottom angle (HSBA) When the dip angle is 18deg LSSArsquosstrain is 2ndash4 times of other sharp angles it changes with thechange in inclination
524 Analysis of Stress Distribution in the Surrounding Rockof the Roadway Floor Figure 15 is a simulated groundstress-strain curve of the surrounding rock of a rectangulartrapezoidal roadway with different dip angles It can be seenfrom Figure 15 that under the action of the upper roof andthe two sets of asymmetric stress the stress distribution ofthe floor of the roadway also exhibits obvious asymmetry
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)0 3 6 9 12 15 18 21 24
0
20
40
60
80
100
120
(c)
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)0 3 6 9 12 15 18 21 24
0
10
20
30
40
50
60
(d)
Figure 10 Analysis curves of the horizontal displacements of the two sides of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Table 3 Horizontal displacement of two sides of roadway (mm)
Dip angleGround stress 10MPa Ground stress 20MPaLow side High side Low side High side
18deg 2254 3747 11551 1925321deg 2389 3131 11464 1590024deg 1493 2301 7288 1068927deg 71 17 2141 5881
8 Advances in Civil Engineering
Data analysis
Computer
Strain gauge
Monitoring point
Loading
07m 01m
072
m
015m
01m
R-high side R-low sideIntermediate
LSSAHSSA
LSBAHSBA
High sideLow side
F-high side F-low side
Figure 11 Test models of the right-angled trapezoidal roadway
0
1
2
3
4
5
6
7
8
0 25 50 75 100 125 150 175Strain (10ndash6)
Stre
ss (M
Pa)
R-high sideIntermediateR-low side
(a)
Strain (10ndash6)
Stre
ss (M
Pa)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
7
0 30 60 90 120 150 180 210
(b)
Stre
ss (M
Pa)
Strain (10ndash6)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
0 40 80 120 160 200 240 280
(c)
Stre
ss (M
Pa)
Strain (10ndash6)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
0 50 100 150 200 250 300 350
(d)
Figure 12 Stress-strain curves of the roof surrounding the rock (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Advances in Civil Engineering 9
0
1
2
3
4
5
6
7
8
0 600 1200 1800 2400 3000
High sideLow side
Stre
ss (M
Pa)
Strain (10ndash6)
(a)
High sideLow side
0
1
2
3
4
5
6
7
0 300 600 900 1200 1500 1800
Stre
ss (M
Pa)
Strain (10ndash6)
(b)
0
1
2
3
4
5
6
0 800 1600 2400 3200
Stre
ss (M
Pa)
High sideLow side
Strain (10ndash6)
(c)
Stre
ss (M
Pa)
0
1
2
3
4
5
0 500 1000 1500 2000 2500
High sideLow side
Strain (10ndash6)
(d)
Figure 13 Stress-strain curve of the surrounding rock of the two sides of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
0
1
2
3
4
5
6
7
8
0 150 300 450 600 750 900
Stre
ss (M
Pa)
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(a)
Stre
ss (M
Pa)
0
1
2
3
4
5
6
7
0 200 400 600 800 1000 1200 1400
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(b)
Figure 14 Continued
10 Advances in Civil Engineering
Stre
ss (M
Pa)
0
1
2
3
4
5
6
0 200 400 600 800 1000 1200
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(c)
Stre
ss (M
Pa)
0
1
2
3
4
5
0 200 400 600 800 1000 1200 1400
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(d)
Figure 14 Stress-strain curve of the surrounding rock at the corner of the roadway (a) 18deg (b) 21deg (c) 27deg (d) 27deg
F-high sideF-low side
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
Stre
ss (M
Pa)
Strain (10ndash6)
(a)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
6
7
0 20 40 60 80 100 120 140 160Strain (10ndash6)
(b)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
6
0 30 60 90 120 150 180Strain (10ndash6)
(c)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
0 25 50 75 100 125Strain (10ndash6)
(d)
Figure 15 Stress-strain curve of roadway floor (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Advances in Civil Engineering 11
and the stress on the right wall of the floor (F-low side) isgreater than that on the left wall of the floor (F-high side)
From the laboratory model test results it can be seen thatthe stress distribution law of the right-angled trapezoidalroadway in a gently inclined seam is similar to the numericalsimulation and the stress distribution of the surroundingrock in the roof the two walls the floor and the corner of theroadway shows clear asymmetric characteristics howeverthere are some differences in the numerical valuese mainreason is that the proportion of similar materials size of themodel loading mode and so on have an impact on the testresults
6 Comparison and Analysis ofSimulation Results
It can be seen from the simulation results that the asym-metric distribution law of the surrounding rock in inclinedright angle trapezoidal roadway is basically the same as thatof large dip angle and steep inclined coal seam roadway butthe degree of stress asymmetry in the inclined coal seam ismuch lower than that of large dip angle coal seam enumerical simulation results of the asymmetric deformationand failure characteristics of the inclined trapezoidal
roadway in the inclined coal seam are consistent with thelaboratory model test (Figure 16) and the site failuremorphology of the Shitanjing No 2 mine (Figure 17) inwhich the deformation and failure law exhibits an asym-metrical feature Further the two walls of the roadway areseverely bulging and the low side is larger than the high side
7 Conclusion
Based on the theory of asymmetric stress distribution in thesurrounding rock of right-angled trapezoidal roadway in aninclined coal seam and considering the Shijiajing No 2mining area as the engineering background this paperfurther analyzes the asymmetric distribution characteristicsof the surrounding rock by using the FLAC3D finite dif-ference method rough verifications with a simulationtest the following conclusions were drawn
(1) e stress distribution of the surrounding rock of theright-angled trapezoidal roadway in the inclined coalseam shows clear asymmetryemain performanceis that the peak value of stress concentration in thelow side is greater than that in the high side and thedistance between the high side and the side wall ofthe roadway is greater than that in the low side With
(a) (b)
Figure 16 Deformation and failure of roadway in laboratory model test (a) 24deg (b) 27deg
(a) (b)
Figure 17 Deformation and failure of roadway in Shitanjing No 2 mine (a) 24deg (b) 27deg
12 Advances in Civil Engineering
the increase in the inclination angle and groundstress the difference between the peak value of stressconcentration and the distance from the side wall ofthe roadway is more obvious When the inclinationangle is 18degndash27deg the peak value of stress concen-tration of the low side is 107ndash133 times that of thehigh side and the distance from the high side to theside wall of the roadway is 126ndash379m larger thanthat of the low side Second two sharp corners thatare symmetric with the same inclination angle of thecoal seam show obvious compressive stress regionswhile the opposite two sharp corners show obvioustensile stress regions e maximum values ofcompressive and tensile stresses appear on the roof ofthe roadway
(2) Under the action of asymmetric stress the defor-mation and failure of the roadway surrounding therock also presents asymmetric characteristics etwo walls of the roadway exhibit extrusion dislo-cation and serious deformation and damage how-ever the deformation damage of the low side isobviously larger than that at the high side e mainreason is that the difference in height between thetwo walls of the roadway leads to the uneven dis-tribution of stress
(3) e results of numerical simulation are basicallyconsistent with laboratory model test and field en-gineering However there are some differences in thedata obtained and the main reason is that the two areaffected by the selection of the simulation parame-ters ratio of similar materials size of the model andloading method
Data Availability
e data used to support the findings of this study are in-cluded within the article
Conflicts of Interest
e authors declare that they have no conflicts of interestregarding the publication of this paper
Acknowledgments
is study was financially supported by the National NaturalScience Foundation of China (51174159 and 59974019) theChina Postdoctoral Science Foundation (2015M572580)and the Scientific Research Plan Projects of EducationDepartment of Shanxi Province of China (15JK1471)
Supplementary Materials
eoretical analysis process of roof stress distribution ininclined coal seam roadway (Supplementary Materials)
References
[1] H C Li ldquoStudy on deformation and failure characteristicsand stability control of large dip angle thick compound roofroadwayrdquo Dissertation Taiyuan University of TechnologyTaiyuan China 2014
[2] e National Development and Reform Commission PeoplersquosRepublic of China Energy Development 11th Five-Year PlanBeijing China 2007 in Chinese
[3] K Yu L Zhou Q Cao and Z Li ldquoEvolutionary game re-search on symmetry of workersrsquo behavior in coal mine en-terprisesrdquo Symmetry vol 11 no 2 pp 156ndash168 2019
[4] L Si Z Wang R Xu C Tan X Liu and J Xu ldquoImageenhancement for surveillance video of coal mining face basedon single-scale retinex algorithm combined with bilateralfilteringrdquo Symmetry vol 9 no 6 pp 93ndash108 2017
[5] F L He M G Qian and C Y Liu Support System of Supportand Surrounding Rock for High Productivity and High Effi-ciency Working Face China Mining Industry Press XuzhouChina 1997 in Chinese
[6] S J Chen Y Wang Y Z Wu Z Wang and W J ZhangldquoCoal resources and development potential in northwestChinardquo Northwestern Geology vol 4 pp 40ndash56 2006 inChinese
[7] X M Sun and M C He ldquoNumerical simulation research oncoupling support theory of roadway within soft rock atdepthrdquo Journal of China University of Mining and Technologyvol 34 no 2 pp 166ndash169 2005 in Chinese
[8] S X Wei J H Song and H W Jing ldquoNumerical analysis ofstress in the surrounding rock of the dynamic pressure tunnelwith inclined seamsrdquo Metal Mine vol 41 no 3 pp 37ndash412012 in Chinese
[9] H Wang B Xia Y Lu T Gong and R Zhang ldquoStudy on thepropagation laws of hydrofractures meeting a faulted struc-ture in the coal seamrdquo Energies vol 10 no 5 pp 654ndash6722017
[10] J Xie J Xu and FWang ldquoMining-induced stress distributionof the working face in a kilometer-deep coal mine-a case studyin Tangshan coal minerdquo Journal of Geophysics and Engi-neering vol 15 no 5 pp 2060ndash2070 2018
[11] S Zhang X Wang G Fan D Zhang and C Jianbin ldquoPillarsize optimization design of isolated island panel gob-sideentry driving in deep inclined coal seam-case study ofPingmei No 6 coal seamrdquo Journal of Geophysics and Engi-neering vol 15 no 3 pp 816ndash828 2018
[12] Y Yuan S Tu F Wang X Zhang and B Li ldquoHydraulicsupport instability mechanism and its control in a fully-mechanized steep coal seam working face with large miningheightrdquo Journal of the Southern African Institute of Miningand Metallurgy vol 115 no 5 pp 441ndash447 2015
[13] J Sun L Wang and G Zhao ldquoFailure characteristics andconfined permeability of an inclined coal seam floor in fluid-solid couplingrdquo Advances in Civil Engineering vol 2018Article ID 2356390 12 pages 2018
[14] S Gu B Jiang G Wang H Dai and M Zhang ldquoOccurrencemechanism of roof-fall accidents in large-section coal seamroadways and related support design for Bayangaole coalmine Chinardquo Advances in Civil Engineering vol 2018 ArticleID 6831731 17 pages 2018
[15] H Xie M Gao R Zhang G Peng W Wang and A LildquoStudy on the mechanical properties andmechanical response
Advances in Civil Engineering 13
of coal mining at 1000m or deeperrdquo RockMechanics and RockEngineering vol 52 no 5 pp 1475ndash1490 2019
[16] Y Fang C Xu G Cui and B Kenneally ldquoScale model test ofhighway tunnel construction underlying mined-out thin coalseamrdquo Tunnelling and Underground Space Technology vol 56pp 105ndash116 2016
[17] M C He ldquoPhysical modeling of an underground roadwayexcavation in geologically 45deg inclined rock using infraredthermographyrdquo Engineering Geology vol 121 no 3-4pp 165ndash176 2011
[18] W Gong Y Peng M He and J Wang ldquoermal image andspectral characterization of roadway failure process in geo-logically 45deg inclined rocksrdquo Tunnelling and UndergroundSpace Technology vol 49 pp 156ndash173 2015
[19] H Yang S Cao Y Li C Sun and P Guo ldquoSoft roof failuremechanism and supporting method for gob-side entryretainingrdquo Minerals vol 5 no 4 pp 707ndash722 2015
[20] L Q Ma Y Zhang D S Zhang X Q Cao Q Q Li andY B Zhang ldquoSupport stability mechanism in a coal face withlarge angles in both strike and diprdquo Journal of the SouthernAfrican Institute of Mining and Metallurgy vol 115 no 7pp 599ndash606 2015
[21] M Jawed and R K Sinha ldquoDesign of rhombus coal pillars andsupport for roadway stability and mechanizing loading of facecoal using SDLs in a steeply inclined thin coal seammdashatechnical feasibility studyrdquo Arabian Journal of Geosciencesvol 11 no 15 pp 415ndash429 2018
[22] Y Yin J Zou Y Zhang Y Qiu and K Fang ldquoExperimentalstudy of the movement of backfilling gangues for goaf insteeply inclined coal seamsrdquo Arabian Journal of Geosciencesvol 11 no 12 pp 318ndash326 2018
[23] L Q Zhu and Y Zhang ldquoAnalysis of spontaneous com-bustion ldquothree zonesrdquo in 3237 working face of zhaogezhuangminerdquo Applied Mechanics and Materials vol 71ndash78pp 1978ndash1982 2011
[24] S Q He D Z Song Z L Li et al ldquoPrecursor of spatio-temporal evolution law of MS and AE activities for rock burstwarning in steeply inclined and extremely thick coal seamsunder caving mining conditionsrdquo Rock Mechanics and RockEngineering no 2 pp 1ndash21 2019
[25] H S Tu S H Tu Y Yuan F T Wang and Q S Bai ldquoPresentsituation of fully mechanized mining technology for steeplyinclined coal seams in Chinardquo Arabian Journal of Geosciencesvol 8 no 7 pp 1978ndash1982 2015
[26] W Lv Y Wu L Ming and J Yin ldquoMigration law of the roofof a composited backfilling longwall face in a steeply dippingcoal seamrdquo Minerals vol 9 no 3 pp 188ndash203 2019
[27] Z Bei S G Cao L G Wang and Y L Lu ldquoDeformationfailure mechanism and support measurements in roadway ofsteeply inclined coal seamrdquo Journal of Mining amp Safety En-gineering vol 28 no 2 pp 214ndash219 2011
[28] M Z Gao and H Q Jing ldquoMechanical analysis of asymmetricfloor heave of roadwayrdquo Journal of Anhui University of Scienceand Technology vol 32 no 4 pp 38ndash43 2012 in Chinese
[29] J G Liu A Y Cao Z M Yu G C Jing and H Y Liu ldquoStudyon stress characteristics of roadwayrsquos sides in deep and in-clined seamrdquo China Coal vol 42 no 8 pp 30ndash34 2016 inChinese
[30] X H Qi ldquoStudy on deformation characters and supportparameters of large angle seam roadway rock aroundrdquo Dis-sertation Xirsquoan University of Science and Technology XirsquoanChina 2015 in chinese
14 Advances in Civil Engineering
erefore it is of great theoretical value and practical sig-nificance to conduct numerical simulations and analyze thestress asymmetry characteristics of right-angled trapezoidalroadways in gently inclined seams for stability evaluation
In the inclined coal seam the roadway is usuallyarranged along the roof middle and bottom of the coalseam e location of the roadway in the coal seam isdifferent resulting in different cross-sectional shapes ofthe roadway e Shitanjing No 2 mining area is locatedin the western high-mountain area It is a typical gentlyinclined coal seam with a dip angle of 18ndash27deg ethickness of the recoverable coal seam is 55ndash606 m eroadway is excavated along the roof of the coal seam toform a right-angled trapezoidal roadway Taking theShitanjing No 2 mining area as the engineering back-ground theoretical analysis and numerical modelingwith FLAC3D software are used to study the asymmetricdistribution of surrounding rock stress in a right-angledtrapezoidal roadway with an inclined dip angle Based onthe engineering background of the Shitanjing No 2mining area in this research the asymmetric stressdistribution law of the surrounding rock of the right-angled trapezoidal roadway in different inclined seams isevaluated by theoretical analysis and numerical simu-lations using FLAC3D and verified via laboratory modeltests and practical engineering application which pro-vide the scientific basis for the selection of supportingschemes for the right-angled trapezoidal roadway in thisarea
2 Analysis of Asymmetric Characteristics of theStress in the Surrounding Rocks ofthe Roadway
Numerous scholars have discovered that after the exca-vation of an inclined coal seam roadway the stress re-distribution around the roadway exhibits obviousasymmetric characteristics and the stress distributionbetween the two walls of the roadway and the roof and flooris obviously different under the action of the overlyingstrata load [28ndash30] As can be observed from Figure 1 thestress acting on the roadway is characterized by the shearstress σx along the inclined direction of the coal seam andthe compressive stress σy perpendicular to the coal seamowing to the influence of the dip angle of the seame highside is subjected to a tensile force σx parallel to the directionof the coal body while the low side is subjected to asqueezing force σy (Figure 1)
is asymmetry and nonhomogeneous stress statelead to stress concentration peak value on the right wall(low side) being greater than that on the left wall (highside) and the distances from the points with the peakstress concentrations at the high and low sides to bothwalls of the roadway are different (Figure 2) Accordingto the formula for the width of the stress limit equilib-rium zone the distance between the stress concentrationareas A and B and the wall of the roadway can be cal-culated as xA and xB respectively as shown in equations(1) and (2)
xA mAf
2tgφ0ln
kAch + c0tgφ0( 1113857
c0tgφ0( 1113857 + Pxf( 11138571113888 1113889 (1)
xB mBf
2tgφ0ln
kBch + c0tgφ0( 1113857
c0tgφ0( 1113857 + Pxf( 11138571113888 1113889 (2)
where xA and xB are the widths of the stress limitequilibrium zone (m) mA and mB denote the height of theroadway (m) f is the lateral pressure coefficient φ0 is thefriction angle of composite coal rock (deg) kA and kB denote thepressure rise coefficients h is the coal mining depth (m) c0 isthe cohesive force between the coal seam and roof rockstratum (MPa) c is the bulk density (kgmiddotm3) and Px is thesupport resistance to coal support (MPa)
It can be seen from equations (1) and (2) that the dis-tances from the stress concentration areas A and B to the twowalls play a key role in determining the heights of the twowalls of the roadway For the right-angled trapezoidalroadway in the inclined coal seam the distance from thestress concentration area of the high side to the wall of theroadway is larger than that of the low side because of theobvious difference between the heights of the high and lowsides
Roadway
σx
σx
σy
σy
τ
τ
High side
Low side
Figure 1 Stress decomposition map of the surrounding rock oftwo laneways
xA
xB
kAγH
kBγHγH
γH
xA gt xBkAγH lt kBγH
RoadwayA
B
Stressconcentration
locationStress
concentrationlocation
High side
Low side
Figure 2 Stress distribution map of the surrounding rock of twolaneways
2 Advances in Civil Engineering
For the roof of the roadway the stress distribution alsoexhibits obvious asymmetric characteristics that is thestress concentration of the right wall (low side) sharp angleof the roadway roof is greater than the left wall (high side)sharp angle and it changes with the change in inclination asshown in Figure 3 ese values are calculated as follows
σwL 11139465b1
05ab1c1h1dh
σwR 11139466b1minusb2
05a 6b1 minus b2( 1113857c1h1dh
(3)
where σwL and σwR are the stresses at the corners of the highand low sides of the roadway roof (MPa) respectively a isthe width of the roadway (m) c1 is the average rock bulkdensity (kgmiddotm3) h1 is the coal mining depth (m) b1 and b2are the heights of the roadway in the high and low sides (m)respectively
In conclusion under the asymmetric stress of the sur-rounding rock of the right angle trapezoid roadway in theinclined coal seam the deformation and failure of thesurrounding rock of roadway also presents obvious asym-metric characteristics e two walls of the roadway aresqueezed and dislocated on the inside and bulge out con-siderably e damage on the low side is greater than that inthe high side and the greatest damage is observed in the twocorners of the low side
3 Model Establishment andParameter Selection
Based on the Mohr Coulomb criterion a numerical model isestablished using the numerical simulation softwareFLAC3D (Figure 4) emodel size is 36mtimes 5mtimes 36m thefour walls are constrained in the normal direction the topsurface is the ground surface and the surface is the freeboundary of stress and displacement the bottom boundaryis subjected to horizontal and vertical constraints and thetop of the model is the overlying rock layer Four typicalcalculation models with inclination angles of 18deg 21deg 24degand 27deg were established and stresses of 25MPa 5MPa10MPa 15MPa and 20MPa were applied e asymmetricdistribution characteristics of surrounding rock stress in theright-angled trapezoidal roadway were analyzed Accordingto the coal seam geological conditions of the Shitanjing No 2mining area the physical and mechanical parameters of thesurrounding rock are selected as given in Table 1
4 Numerical Simulation Analysis
41 Vertical Stress Distribution Characteristics of RoadwayFigure 5 shows the vertical stress nephogram of the right-angled roadway in different inclined seams under a simu-lated ground stress of 25MPa It can be seen from the figurethat the stress concentration on the right wall (low side) ofthe roadway is greater than that on the left wall (high side)e distance from the stress concentration area of the leftwall (high side) to the side of the roadway is greater than thatof the right wall (low side) e stress concentration on the
roof of the roadway deviates toward the life wall (high side)and the stress concentration on the floor deviates toward theright wall (low side) and changes with the inclination angle
Figure 6 is the curve of the stress concentration peakvalue of the right-angled trapezoidal roadway for differentinclined seams with simulated ground stress q Figure 6displays that the stress concentration peak values of bothwalls of the roadway increases with the increase in incli-nation and ground stress When the inclination angle is18ndash27deg the stress concentration peak value of the low side is107ndash133 times greater than that of the high side Howeverunder the action of small ground stress the difference inpeak stress between the two walls is not very obvious mainlybecause of the influence of the dip angle
Figure 7 is the curve of the distance from the peak stressconcentration to both the walls of the right-angled trape-zoidal roadway in the inclined coal seam with differentground stresses e distances from the points at which thepeak values of stress concentration occur on the two walls ofthe roadway to the sides of the roadway are obviouslydifferent and increase with the increase in inclination andground stress as shown in Figure 7 and Table 2 When theinclination is 18ndash27deg and the ground stress is 10MPa at thehigh side of the roadway the stress concentration peak to thedistance of the side wall of the roadway is 128ndash300mmgreater than that at the low side When the ground stress is10ndash20MPa and the inclination is 18deg at the high side of theroadway the stress concentration peak to the side wall of theroadway is greater than that at the low side which is126ndash136mm However with the increase in inclinationangle the distances from the points with peak stress con-centrations at the two sides to the walls of the roadwaybecome progressively smaller
42 Horizontal Stress Distribution Characteristics of theRoadway Figure 8 shows the horizontal stress nephogramof the right-angled trapezoidal roadway in different inclinedseams under a simulated ground stress of 25MPa It can beseen from Figure 8 that the two cusps symmetrical with thedip angle of the coal seam show an obvious compressivestress zone while the opposite direction shows an obvioustensile stress zone and the maximum values of the com-pressive and tensile stresses appear at the two cusps of theroof of the roadway With the increase in inclination anglethe stress concentration at the corner of the roadwaydecreases
a
b2
b1
Roadway
High side
Low side
Figure 3 Stress distribution at the roof of the laneway
Advances in Civil Engineering 3
Table 1 Numerical simulation of physical and mechanical parameters of coal and rock
Rock stratum ickness(m)
Density(kgmiddotmminus3)
Bulk modulus(GPa)
Shear modulus(GPa)
Friction(deg)
Cohesion(MPa)
Tension(MPa)
(1) Siltstone 46 2 460 849 647 321 57 377(2) Medium grainsandstone 4 2 510 1011 727 370 118 278
(3) Mudstone 29 2 530 779 534 315 185 154(4) Coal seam 55 1 400 180 083 210 160 050(5) Siltstone 92 2 460 849 647 321 57 377
Stress (Pa)ndash48069E + 05ndash50000E + 05ndash75000E + 05ndash10000E + 06ndash12500E + 06ndash15000E + 06ndash17500E + 06ndash20000E + 06ndash22500E + 06ndash25000E + 06ndash27500E + 06ndash30000E + 06ndash32500E + 06ndash35000E + 06ndash37500E + 06ndash40000E + 06ndash42500E + 06ndash43232E + 06
(a)
Stress (Pa)99217E + 0400000E + 00ndash25000E + 05ndash50000E + 05ndash75000E + 05ndash10000E + 06ndash12500E + 06ndash15000E + 06ndash17500E + 06ndash20000E + 06ndash22500E + 06ndash25000E + 06ndash27500E + 06ndash30000E + 06ndash32500E + 06ndash35000E + 06
ndash42500E + 06ndash45000E + 06ndash45879E + 06
ndash37500E + 06ndash40000E + 06
(b)
Stress (Pa)ndash12397E + 06ndash12500E + 06ndash15000E + 06ndash17500E + 06ndash20000E + 06ndash22500E + 06ndash25000E + 06ndash27500E + 06ndash30000E + 06ndash32500E + 06ndash35000E + 06ndash37500E + 06ndash40000E + 06ndash40781E + 06
(c)
Stress (Pa)ndash17537E + 06ndash18000E + 06ndash20000E + 06ndash22000E + 06ndash24000E + 06ndash26000E + 06ndash28000E + 06ndash30000E + 06ndash32000E + 06
ndash38000E + 06ndash40000E + 06ndash40627E + 06
ndash34000E + 06ndash36000E + 06
(d)
Figure 5 Vertical stress nephogram of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
36m
3m
36m
5m
45m
18deg21deg24deg27deg
SiltstoneMedium grain sandstoneMudstoneCoal seam
Siltstone
Roadway
Figure 4 Numerical calculation model
4 Advances in Civil Engineering
0 3 6 9 12 15 18 21 240
5
10
15
20
25
30
35
40
High sideLow side
Stre
ss (M
Pa)
q (MPa)
(a)
High sideLow side
q (MPa)0 3 6 9 12 15 18 21 24
0
5
10
15
20
25
30
35
40
45
Stre
ss (M
Pa)
(b)
High sideLow side
q (MPa)0 3 6 9 12 15 18 21 24
0
5
10
15
20
25
30
35
40
Stre
ss (M
Pa)
(c)
High sideLow side
q (MPa)0 3 6 9 12 15 18 21 24
0
5
10
15
20
25
30
35
40
Stre
ss (M
Pa)
(d)
Figure 6 Comparative analysis curves of peak stress and ground stress of the two sides of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
15 18 21 24 27 300
3
6
9
12
Dip angle (deg)
High sideLow side
Dist
ance
(m)
(a)
Dip angle (deg)
High sideLow side
Dist
ance
(m)
15 18 21 24 27 303
6
9
12
15
(b)
Figure 7 Curve of the change in stress concentration peak with the side distance of the two sides of the roadway with inclination angle (a)10MPa (b) 20MPa
Advances in Civil Engineering 5
43 Horizontal Displacement Characteristics of the RoadwayFigures 9 and 10 depict the horizontal stress nephogram ofthe roadway and the displacement analysis diagram of thetwo walls of the roadway with different simulated groundstresses q and different inclination angles respectivelyFigures 9 and 10 and Table 3 reveal that the displacementdifference between the two walls of the roadway is obviousand increases with the increase in group stress e groupstress is 10ndash15MPa and the inclination angle is 18deg and theroadwayrsquos high side is 15ndash77mm larger than the low sideHowever the difference decreases with the increase in in-clination angle When the inclination angle is 18ndash27deg and thegroup stress is 10MPa the roadwayrsquos high side is 15ndash10mm
larger than the low side e main reason is that the dif-ference in height between the two walls leads to unevenstress distribution
5 Validation of the Simulation Test
51 Test Plan To verify the asymmetric stress distributioncharacteristics of the surrounding rock of the right-angledtrapezoidal roadway in the inclined seam further the lab-oratory model test adopted the principle of geometricsimilarity and strength equality and established four types ofright-angled trapezoidal roadway test models with differentinclined seam angles namely 18deg 21deg 24deg and 27deg
Table 2 Distance from peak stress concentration to both sides of roadway (mm)
Dip angleGround stress 10MPa Ground stress 20MPa
Low side High side Low side High side18deg 642 514 1203 106721deg 605 405 1185 98524deg 54 29 1118 83827deg 501 201 1055 665
70522E + 0570000E + 0560000E + 0550000E + 0540000E + 0530000E + 0520000E + 0510000E + 0500000E + 00ndash10000E + 05ndash20000E + 05ndash30000E + 05ndash40000E + 05ndash50000E + 05ndash60000E + 05ndash70000E + 05ndash80000E + 05ndash90000E + 05ndash90594E + 05
Stress (Pa)
(a)
94567E + 0580000E + 0560000E + 0540000E + 0520000E + 0500000E + 00ndash20000E + 05ndash40000E + 05ndash60000E + 05ndash80000E + 05ndash10000E + 06ndash11309E + 06
Stress (Pa)
(b)
ndash10000E + 05ndash20000E + 05ndash30000E + 05ndash40000E + 05ndash50000E + 05ndash60000E + 05ndash70000E + 05ndash76621E + 05
39580E + 0530000E + 0520000E + 0510000E + 0500000E + 00
Stress (Pa)
(c)
ndash10000E + 05ndash20000E + 05ndash30000E + 05ndash40000E + 05ndash50000E + 05ndash60000E + 05ndash64765E + 05
39675E + 0530000E + 0520000E + 0510000E + 0500000E + 00
Stress (Pa)
(d)
Figure 8 Horizontal stress distribution characteristics of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
6 Advances in Civil Engineering
Displacement (m)
ndash50000E ndash 04ndash10000E ndash 03ndash15000E ndash 03ndash20000E ndash 03ndash22092E ndash 03
35007E ndash 03
30000E ndash 0335000E ndash 03
25000E ndash 0320000E ndash 0315000E ndash 0310000E ndash 0350000E ndash 0400000E + 00
(a)
Displacement (m)
ndash25000E ndash 04ndash50000E ndash 04ndash75000E ndash 04ndash10000E ndash 03ndash12500E ndash 03ndash12767E ndash 03
20000E ndash 0321873E ndash 03
15000E ndash 0317500E ndash 03
12500E ndash 0310000E ndash 0375000E ndash 0450000E ndash 0425000E ndash 0400000E + 00
(b)
Displacement (m)
ndash25000E ndash 04ndash50000E ndash 04ndash75000E ndash 04ndash10000E ndash 03ndash12500E ndash 03ndash15000E ndash 03ndash17500E ndash 03ndash18776E ndash 03
20000E ndash 03
15000E ndash 0317500E ndash 03
12500E ndash 0310000E ndash 03
26609E ndash 0325000E ndash 0322500E ndash 03
75000E ndash 0450000E ndash 0425000E ndash 0400000E + 00
(c)
Displacement (m)
ndash25000E ndash 04ndash50000E ndash 04ndash75000E ndash 04ndash10000E ndash 03ndash10040E ndash 03
15000E ndash 0316911E ndash 03
12500E ndash 0310000E ndash 0375000E ndash 0450000E ndash 0425000E ndash 0400000E + 00
(d)
Figure 9 Horizontal stress distribution characteristics of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
0 3 6 9 12 15 18 21 240
30
60
90
120
150
180
210
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)
(a)
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)0 3 6 9 12 15 18 21 24
0
30
60
90
120
150
180
(b)
Figure 10 Continued
Advances in Civil Engineering 7
(Figure 11)e geometric similarity ratio is 1 30 the modelsize is 72 cmtimes 72 cmtimes 10 cm and the lithology parametersare selected from the engineering background of the Shi-tanjing No 2 mining area which is the same as that for thenumerical simulation Different proportions of cementmortar were used to simulate the characteristics
e measurement points are arranged at the roadwaywalls roof and floor as well as the corners A verticaluniform load is applied to the model in a stepwise manneruntil the specimen is completely destroyede strain valuesof each measurement point under different loads arerecorded in real time during the loading process
52 Analysis of Test Results
521 Stress Distribution Law of the Roof Surrounding theRock Figure 12 displays a simulated ground stress-straincurve of the roof surrounding the rock of the trapezoidalroadway with different dip angles e stress of the roofsurrounding the rock of the roadway presents obviousasymmetric characteristics and the size distribution of themiddle measuring point of the roof (Intermediate)gt the lowside measuring point of the roof (R- low side)gt the high sidemeasuring point of the roof (R- high side) from Figure 12 Inaddition the maximum strain on the low side of the sur-rounding rock is significantly larger than that on the highside e greater the dip angle the more obvious the dif-ference in stress distribution between the high and low sides
of the surrounding rock of the roadway When the incli-nation angle is in the range of 18degndash27deg the maximum strainon the right wall of the roof (R- low side) is 13ndash21 timeslarger than that on the left wall of the roof (R- high side)
522 Stress Distribution Law of the Surrounding Rocks of theTwo Walls of the Roadway Figure 13 describes the simu-lated ground stress-strain curve of the surrounding rock ofthe right-angled trapezoidal roadway with different dipangles It can be concluded that the stress concentrations onthe two walls of the roadway are clearly different and theyincrease with increasing inclination and ground stress einclination angle is 18degndash27deg and the maximum value of theright wall (low side) stress concentration is 12ndash17 times thatof the left wall (high side)
523 Stress Distribution Law of the Two Surrounding RocksFigure 14 is a simulated ground stress-strain curve of thesurrounding rock at the corners of a right-angled trapezoidalroadway with different dip angles Figure 14 reveals that thestress distribution of each point at the four corners of theroadway is different From large to small the order is lowside shoulder angle (LSSA) high side shoulder angle(HSSA) low side bottom angle (LSBA) and high sidebottom angle (HSBA) When the dip angle is 18deg LSSArsquosstrain is 2ndash4 times of other sharp angles it changes with thechange in inclination
524 Analysis of Stress Distribution in the Surrounding Rockof the Roadway Floor Figure 15 is a simulated groundstress-strain curve of the surrounding rock of a rectangulartrapezoidal roadway with different dip angles It can be seenfrom Figure 15 that under the action of the upper roof andthe two sets of asymmetric stress the stress distribution ofthe floor of the roadway also exhibits obvious asymmetry
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)0 3 6 9 12 15 18 21 24
0
20
40
60
80
100
120
(c)
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)0 3 6 9 12 15 18 21 24
0
10
20
30
40
50
60
(d)
Figure 10 Analysis curves of the horizontal displacements of the two sides of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Table 3 Horizontal displacement of two sides of roadway (mm)
Dip angleGround stress 10MPa Ground stress 20MPaLow side High side Low side High side
18deg 2254 3747 11551 1925321deg 2389 3131 11464 1590024deg 1493 2301 7288 1068927deg 71 17 2141 5881
8 Advances in Civil Engineering
Data analysis
Computer
Strain gauge
Monitoring point
Loading
07m 01m
072
m
015m
01m
R-high side R-low sideIntermediate
LSSAHSSA
LSBAHSBA
High sideLow side
F-high side F-low side
Figure 11 Test models of the right-angled trapezoidal roadway
0
1
2
3
4
5
6
7
8
0 25 50 75 100 125 150 175Strain (10ndash6)
Stre
ss (M
Pa)
R-high sideIntermediateR-low side
(a)
Strain (10ndash6)
Stre
ss (M
Pa)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
7
0 30 60 90 120 150 180 210
(b)
Stre
ss (M
Pa)
Strain (10ndash6)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
0 40 80 120 160 200 240 280
(c)
Stre
ss (M
Pa)
Strain (10ndash6)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
0 50 100 150 200 250 300 350
(d)
Figure 12 Stress-strain curves of the roof surrounding the rock (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Advances in Civil Engineering 9
0
1
2
3
4
5
6
7
8
0 600 1200 1800 2400 3000
High sideLow side
Stre
ss (M
Pa)
Strain (10ndash6)
(a)
High sideLow side
0
1
2
3
4
5
6
7
0 300 600 900 1200 1500 1800
Stre
ss (M
Pa)
Strain (10ndash6)
(b)
0
1
2
3
4
5
6
0 800 1600 2400 3200
Stre
ss (M
Pa)
High sideLow side
Strain (10ndash6)
(c)
Stre
ss (M
Pa)
0
1
2
3
4
5
0 500 1000 1500 2000 2500
High sideLow side
Strain (10ndash6)
(d)
Figure 13 Stress-strain curve of the surrounding rock of the two sides of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
0
1
2
3
4
5
6
7
8
0 150 300 450 600 750 900
Stre
ss (M
Pa)
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(a)
Stre
ss (M
Pa)
0
1
2
3
4
5
6
7
0 200 400 600 800 1000 1200 1400
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(b)
Figure 14 Continued
10 Advances in Civil Engineering
Stre
ss (M
Pa)
0
1
2
3
4
5
6
0 200 400 600 800 1000 1200
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(c)
Stre
ss (M
Pa)
0
1
2
3
4
5
0 200 400 600 800 1000 1200 1400
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(d)
Figure 14 Stress-strain curve of the surrounding rock at the corner of the roadway (a) 18deg (b) 21deg (c) 27deg (d) 27deg
F-high sideF-low side
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
Stre
ss (M
Pa)
Strain (10ndash6)
(a)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
6
7
0 20 40 60 80 100 120 140 160Strain (10ndash6)
(b)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
6
0 30 60 90 120 150 180Strain (10ndash6)
(c)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
0 25 50 75 100 125Strain (10ndash6)
(d)
Figure 15 Stress-strain curve of roadway floor (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Advances in Civil Engineering 11
and the stress on the right wall of the floor (F-low side) isgreater than that on the left wall of the floor (F-high side)
From the laboratory model test results it can be seen thatthe stress distribution law of the right-angled trapezoidalroadway in a gently inclined seam is similar to the numericalsimulation and the stress distribution of the surroundingrock in the roof the two walls the floor and the corner of theroadway shows clear asymmetric characteristics howeverthere are some differences in the numerical valuese mainreason is that the proportion of similar materials size of themodel loading mode and so on have an impact on the testresults
6 Comparison and Analysis ofSimulation Results
It can be seen from the simulation results that the asym-metric distribution law of the surrounding rock in inclinedright angle trapezoidal roadway is basically the same as thatof large dip angle and steep inclined coal seam roadway butthe degree of stress asymmetry in the inclined coal seam ismuch lower than that of large dip angle coal seam enumerical simulation results of the asymmetric deformationand failure characteristics of the inclined trapezoidal
roadway in the inclined coal seam are consistent with thelaboratory model test (Figure 16) and the site failuremorphology of the Shitanjing No 2 mine (Figure 17) inwhich the deformation and failure law exhibits an asym-metrical feature Further the two walls of the roadway areseverely bulging and the low side is larger than the high side
7 Conclusion
Based on the theory of asymmetric stress distribution in thesurrounding rock of right-angled trapezoidal roadway in aninclined coal seam and considering the Shijiajing No 2mining area as the engineering background this paperfurther analyzes the asymmetric distribution characteristicsof the surrounding rock by using the FLAC3D finite dif-ference method rough verifications with a simulationtest the following conclusions were drawn
(1) e stress distribution of the surrounding rock of theright-angled trapezoidal roadway in the inclined coalseam shows clear asymmetryemain performanceis that the peak value of stress concentration in thelow side is greater than that in the high side and thedistance between the high side and the side wall ofthe roadway is greater than that in the low side With
(a) (b)
Figure 16 Deformation and failure of roadway in laboratory model test (a) 24deg (b) 27deg
(a) (b)
Figure 17 Deformation and failure of roadway in Shitanjing No 2 mine (a) 24deg (b) 27deg
12 Advances in Civil Engineering
the increase in the inclination angle and groundstress the difference between the peak value of stressconcentration and the distance from the side wall ofthe roadway is more obvious When the inclinationangle is 18degndash27deg the peak value of stress concen-tration of the low side is 107ndash133 times that of thehigh side and the distance from the high side to theside wall of the roadway is 126ndash379m larger thanthat of the low side Second two sharp corners thatare symmetric with the same inclination angle of thecoal seam show obvious compressive stress regionswhile the opposite two sharp corners show obvioustensile stress regions e maximum values ofcompressive and tensile stresses appear on the roof ofthe roadway
(2) Under the action of asymmetric stress the defor-mation and failure of the roadway surrounding therock also presents asymmetric characteristics etwo walls of the roadway exhibit extrusion dislo-cation and serious deformation and damage how-ever the deformation damage of the low side isobviously larger than that at the high side e mainreason is that the difference in height between thetwo walls of the roadway leads to the uneven dis-tribution of stress
(3) e results of numerical simulation are basicallyconsistent with laboratory model test and field en-gineering However there are some differences in thedata obtained and the main reason is that the two areaffected by the selection of the simulation parame-ters ratio of similar materials size of the model andloading method
Data Availability
e data used to support the findings of this study are in-cluded within the article
Conflicts of Interest
e authors declare that they have no conflicts of interestregarding the publication of this paper
Acknowledgments
is study was financially supported by the National NaturalScience Foundation of China (51174159 and 59974019) theChina Postdoctoral Science Foundation (2015M572580)and the Scientific Research Plan Projects of EducationDepartment of Shanxi Province of China (15JK1471)
Supplementary Materials
eoretical analysis process of roof stress distribution ininclined coal seam roadway (Supplementary Materials)
References
[1] H C Li ldquoStudy on deformation and failure characteristicsand stability control of large dip angle thick compound roofroadwayrdquo Dissertation Taiyuan University of TechnologyTaiyuan China 2014
[2] e National Development and Reform Commission PeoplersquosRepublic of China Energy Development 11th Five-Year PlanBeijing China 2007 in Chinese
[3] K Yu L Zhou Q Cao and Z Li ldquoEvolutionary game re-search on symmetry of workersrsquo behavior in coal mine en-terprisesrdquo Symmetry vol 11 no 2 pp 156ndash168 2019
[4] L Si Z Wang R Xu C Tan X Liu and J Xu ldquoImageenhancement for surveillance video of coal mining face basedon single-scale retinex algorithm combined with bilateralfilteringrdquo Symmetry vol 9 no 6 pp 93ndash108 2017
[5] F L He M G Qian and C Y Liu Support System of Supportand Surrounding Rock for High Productivity and High Effi-ciency Working Face China Mining Industry Press XuzhouChina 1997 in Chinese
[6] S J Chen Y Wang Y Z Wu Z Wang and W J ZhangldquoCoal resources and development potential in northwestChinardquo Northwestern Geology vol 4 pp 40ndash56 2006 inChinese
[7] X M Sun and M C He ldquoNumerical simulation research oncoupling support theory of roadway within soft rock atdepthrdquo Journal of China University of Mining and Technologyvol 34 no 2 pp 166ndash169 2005 in Chinese
[8] S X Wei J H Song and H W Jing ldquoNumerical analysis ofstress in the surrounding rock of the dynamic pressure tunnelwith inclined seamsrdquo Metal Mine vol 41 no 3 pp 37ndash412012 in Chinese
[9] H Wang B Xia Y Lu T Gong and R Zhang ldquoStudy on thepropagation laws of hydrofractures meeting a faulted struc-ture in the coal seamrdquo Energies vol 10 no 5 pp 654ndash6722017
[10] J Xie J Xu and FWang ldquoMining-induced stress distributionof the working face in a kilometer-deep coal mine-a case studyin Tangshan coal minerdquo Journal of Geophysics and Engi-neering vol 15 no 5 pp 2060ndash2070 2018
[11] S Zhang X Wang G Fan D Zhang and C Jianbin ldquoPillarsize optimization design of isolated island panel gob-sideentry driving in deep inclined coal seam-case study ofPingmei No 6 coal seamrdquo Journal of Geophysics and Engi-neering vol 15 no 3 pp 816ndash828 2018
[12] Y Yuan S Tu F Wang X Zhang and B Li ldquoHydraulicsupport instability mechanism and its control in a fully-mechanized steep coal seam working face with large miningheightrdquo Journal of the Southern African Institute of Miningand Metallurgy vol 115 no 5 pp 441ndash447 2015
[13] J Sun L Wang and G Zhao ldquoFailure characteristics andconfined permeability of an inclined coal seam floor in fluid-solid couplingrdquo Advances in Civil Engineering vol 2018Article ID 2356390 12 pages 2018
[14] S Gu B Jiang G Wang H Dai and M Zhang ldquoOccurrencemechanism of roof-fall accidents in large-section coal seamroadways and related support design for Bayangaole coalmine Chinardquo Advances in Civil Engineering vol 2018 ArticleID 6831731 17 pages 2018
[15] H Xie M Gao R Zhang G Peng W Wang and A LildquoStudy on the mechanical properties andmechanical response
Advances in Civil Engineering 13
of coal mining at 1000m or deeperrdquo RockMechanics and RockEngineering vol 52 no 5 pp 1475ndash1490 2019
[16] Y Fang C Xu G Cui and B Kenneally ldquoScale model test ofhighway tunnel construction underlying mined-out thin coalseamrdquo Tunnelling and Underground Space Technology vol 56pp 105ndash116 2016
[17] M C He ldquoPhysical modeling of an underground roadwayexcavation in geologically 45deg inclined rock using infraredthermographyrdquo Engineering Geology vol 121 no 3-4pp 165ndash176 2011
[18] W Gong Y Peng M He and J Wang ldquoermal image andspectral characterization of roadway failure process in geo-logically 45deg inclined rocksrdquo Tunnelling and UndergroundSpace Technology vol 49 pp 156ndash173 2015
[19] H Yang S Cao Y Li C Sun and P Guo ldquoSoft roof failuremechanism and supporting method for gob-side entryretainingrdquo Minerals vol 5 no 4 pp 707ndash722 2015
[20] L Q Ma Y Zhang D S Zhang X Q Cao Q Q Li andY B Zhang ldquoSupport stability mechanism in a coal face withlarge angles in both strike and diprdquo Journal of the SouthernAfrican Institute of Mining and Metallurgy vol 115 no 7pp 599ndash606 2015
[21] M Jawed and R K Sinha ldquoDesign of rhombus coal pillars andsupport for roadway stability and mechanizing loading of facecoal using SDLs in a steeply inclined thin coal seammdashatechnical feasibility studyrdquo Arabian Journal of Geosciencesvol 11 no 15 pp 415ndash429 2018
[22] Y Yin J Zou Y Zhang Y Qiu and K Fang ldquoExperimentalstudy of the movement of backfilling gangues for goaf insteeply inclined coal seamsrdquo Arabian Journal of Geosciencesvol 11 no 12 pp 318ndash326 2018
[23] L Q Zhu and Y Zhang ldquoAnalysis of spontaneous com-bustion ldquothree zonesrdquo in 3237 working face of zhaogezhuangminerdquo Applied Mechanics and Materials vol 71ndash78pp 1978ndash1982 2011
[24] S Q He D Z Song Z L Li et al ldquoPrecursor of spatio-temporal evolution law of MS and AE activities for rock burstwarning in steeply inclined and extremely thick coal seamsunder caving mining conditionsrdquo Rock Mechanics and RockEngineering no 2 pp 1ndash21 2019
[25] H S Tu S H Tu Y Yuan F T Wang and Q S Bai ldquoPresentsituation of fully mechanized mining technology for steeplyinclined coal seams in Chinardquo Arabian Journal of Geosciencesvol 8 no 7 pp 1978ndash1982 2015
[26] W Lv Y Wu L Ming and J Yin ldquoMigration law of the roofof a composited backfilling longwall face in a steeply dippingcoal seamrdquo Minerals vol 9 no 3 pp 188ndash203 2019
[27] Z Bei S G Cao L G Wang and Y L Lu ldquoDeformationfailure mechanism and support measurements in roadway ofsteeply inclined coal seamrdquo Journal of Mining amp Safety En-gineering vol 28 no 2 pp 214ndash219 2011
[28] M Z Gao and H Q Jing ldquoMechanical analysis of asymmetricfloor heave of roadwayrdquo Journal of Anhui University of Scienceand Technology vol 32 no 4 pp 38ndash43 2012 in Chinese
[29] J G Liu A Y Cao Z M Yu G C Jing and H Y Liu ldquoStudyon stress characteristics of roadwayrsquos sides in deep and in-clined seamrdquo China Coal vol 42 no 8 pp 30ndash34 2016 inChinese
[30] X H Qi ldquoStudy on deformation characters and supportparameters of large angle seam roadway rock aroundrdquo Dis-sertation Xirsquoan University of Science and Technology XirsquoanChina 2015 in chinese
14 Advances in Civil Engineering
For the roof of the roadway the stress distribution alsoexhibits obvious asymmetric characteristics that is thestress concentration of the right wall (low side) sharp angleof the roadway roof is greater than the left wall (high side)sharp angle and it changes with the change in inclination asshown in Figure 3 ese values are calculated as follows
σwL 11139465b1
05ab1c1h1dh
σwR 11139466b1minusb2
05a 6b1 minus b2( 1113857c1h1dh
(3)
where σwL and σwR are the stresses at the corners of the highand low sides of the roadway roof (MPa) respectively a isthe width of the roadway (m) c1 is the average rock bulkdensity (kgmiddotm3) h1 is the coal mining depth (m) b1 and b2are the heights of the roadway in the high and low sides (m)respectively
In conclusion under the asymmetric stress of the sur-rounding rock of the right angle trapezoid roadway in theinclined coal seam the deformation and failure of thesurrounding rock of roadway also presents obvious asym-metric characteristics e two walls of the roadway aresqueezed and dislocated on the inside and bulge out con-siderably e damage on the low side is greater than that inthe high side and the greatest damage is observed in the twocorners of the low side
3 Model Establishment andParameter Selection
Based on the Mohr Coulomb criterion a numerical model isestablished using the numerical simulation softwareFLAC3D (Figure 4) emodel size is 36mtimes 5mtimes 36m thefour walls are constrained in the normal direction the topsurface is the ground surface and the surface is the freeboundary of stress and displacement the bottom boundaryis subjected to horizontal and vertical constraints and thetop of the model is the overlying rock layer Four typicalcalculation models with inclination angles of 18deg 21deg 24degand 27deg were established and stresses of 25MPa 5MPa10MPa 15MPa and 20MPa were applied e asymmetricdistribution characteristics of surrounding rock stress in theright-angled trapezoidal roadway were analyzed Accordingto the coal seam geological conditions of the Shitanjing No 2mining area the physical and mechanical parameters of thesurrounding rock are selected as given in Table 1
4 Numerical Simulation Analysis
41 Vertical Stress Distribution Characteristics of RoadwayFigure 5 shows the vertical stress nephogram of the right-angled roadway in different inclined seams under a simu-lated ground stress of 25MPa It can be seen from the figurethat the stress concentration on the right wall (low side) ofthe roadway is greater than that on the left wall (high side)e distance from the stress concentration area of the leftwall (high side) to the side of the roadway is greater than thatof the right wall (low side) e stress concentration on the
roof of the roadway deviates toward the life wall (high side)and the stress concentration on the floor deviates toward theright wall (low side) and changes with the inclination angle
Figure 6 is the curve of the stress concentration peakvalue of the right-angled trapezoidal roadway for differentinclined seams with simulated ground stress q Figure 6displays that the stress concentration peak values of bothwalls of the roadway increases with the increase in incli-nation and ground stress When the inclination angle is18ndash27deg the stress concentration peak value of the low side is107ndash133 times greater than that of the high side Howeverunder the action of small ground stress the difference inpeak stress between the two walls is not very obvious mainlybecause of the influence of the dip angle
Figure 7 is the curve of the distance from the peak stressconcentration to both the walls of the right-angled trape-zoidal roadway in the inclined coal seam with differentground stresses e distances from the points at which thepeak values of stress concentration occur on the two walls ofthe roadway to the sides of the roadway are obviouslydifferent and increase with the increase in inclination andground stress as shown in Figure 7 and Table 2 When theinclination is 18ndash27deg and the ground stress is 10MPa at thehigh side of the roadway the stress concentration peak to thedistance of the side wall of the roadway is 128ndash300mmgreater than that at the low side When the ground stress is10ndash20MPa and the inclination is 18deg at the high side of theroadway the stress concentration peak to the side wall of theroadway is greater than that at the low side which is126ndash136mm However with the increase in inclinationangle the distances from the points with peak stress con-centrations at the two sides to the walls of the roadwaybecome progressively smaller
42 Horizontal Stress Distribution Characteristics of theRoadway Figure 8 shows the horizontal stress nephogramof the right-angled trapezoidal roadway in different inclinedseams under a simulated ground stress of 25MPa It can beseen from Figure 8 that the two cusps symmetrical with thedip angle of the coal seam show an obvious compressivestress zone while the opposite direction shows an obvioustensile stress zone and the maximum values of the com-pressive and tensile stresses appear at the two cusps of theroof of the roadway With the increase in inclination anglethe stress concentration at the corner of the roadwaydecreases
a
b2
b1
Roadway
High side
Low side
Figure 3 Stress distribution at the roof of the laneway
Advances in Civil Engineering 3
Table 1 Numerical simulation of physical and mechanical parameters of coal and rock
Rock stratum ickness(m)
Density(kgmiddotmminus3)
Bulk modulus(GPa)
Shear modulus(GPa)
Friction(deg)
Cohesion(MPa)
Tension(MPa)
(1) Siltstone 46 2 460 849 647 321 57 377(2) Medium grainsandstone 4 2 510 1011 727 370 118 278
(3) Mudstone 29 2 530 779 534 315 185 154(4) Coal seam 55 1 400 180 083 210 160 050(5) Siltstone 92 2 460 849 647 321 57 377
Stress (Pa)ndash48069E + 05ndash50000E + 05ndash75000E + 05ndash10000E + 06ndash12500E + 06ndash15000E + 06ndash17500E + 06ndash20000E + 06ndash22500E + 06ndash25000E + 06ndash27500E + 06ndash30000E + 06ndash32500E + 06ndash35000E + 06ndash37500E + 06ndash40000E + 06ndash42500E + 06ndash43232E + 06
(a)
Stress (Pa)99217E + 0400000E + 00ndash25000E + 05ndash50000E + 05ndash75000E + 05ndash10000E + 06ndash12500E + 06ndash15000E + 06ndash17500E + 06ndash20000E + 06ndash22500E + 06ndash25000E + 06ndash27500E + 06ndash30000E + 06ndash32500E + 06ndash35000E + 06
ndash42500E + 06ndash45000E + 06ndash45879E + 06
ndash37500E + 06ndash40000E + 06
(b)
Stress (Pa)ndash12397E + 06ndash12500E + 06ndash15000E + 06ndash17500E + 06ndash20000E + 06ndash22500E + 06ndash25000E + 06ndash27500E + 06ndash30000E + 06ndash32500E + 06ndash35000E + 06ndash37500E + 06ndash40000E + 06ndash40781E + 06
(c)
Stress (Pa)ndash17537E + 06ndash18000E + 06ndash20000E + 06ndash22000E + 06ndash24000E + 06ndash26000E + 06ndash28000E + 06ndash30000E + 06ndash32000E + 06
ndash38000E + 06ndash40000E + 06ndash40627E + 06
ndash34000E + 06ndash36000E + 06
(d)
Figure 5 Vertical stress nephogram of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
36m
3m
36m
5m
45m
18deg21deg24deg27deg
SiltstoneMedium grain sandstoneMudstoneCoal seam
Siltstone
Roadway
Figure 4 Numerical calculation model
4 Advances in Civil Engineering
0 3 6 9 12 15 18 21 240
5
10
15
20
25
30
35
40
High sideLow side
Stre
ss (M
Pa)
q (MPa)
(a)
High sideLow side
q (MPa)0 3 6 9 12 15 18 21 24
0
5
10
15
20
25
30
35
40
45
Stre
ss (M
Pa)
(b)
High sideLow side
q (MPa)0 3 6 9 12 15 18 21 24
0
5
10
15
20
25
30
35
40
Stre
ss (M
Pa)
(c)
High sideLow side
q (MPa)0 3 6 9 12 15 18 21 24
0
5
10
15
20
25
30
35
40
Stre
ss (M
Pa)
(d)
Figure 6 Comparative analysis curves of peak stress and ground stress of the two sides of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
15 18 21 24 27 300
3
6
9
12
Dip angle (deg)
High sideLow side
Dist
ance
(m)
(a)
Dip angle (deg)
High sideLow side
Dist
ance
(m)
15 18 21 24 27 303
6
9
12
15
(b)
Figure 7 Curve of the change in stress concentration peak with the side distance of the two sides of the roadway with inclination angle (a)10MPa (b) 20MPa
Advances in Civil Engineering 5
43 Horizontal Displacement Characteristics of the RoadwayFigures 9 and 10 depict the horizontal stress nephogram ofthe roadway and the displacement analysis diagram of thetwo walls of the roadway with different simulated groundstresses q and different inclination angles respectivelyFigures 9 and 10 and Table 3 reveal that the displacementdifference between the two walls of the roadway is obviousand increases with the increase in group stress e groupstress is 10ndash15MPa and the inclination angle is 18deg and theroadwayrsquos high side is 15ndash77mm larger than the low sideHowever the difference decreases with the increase in in-clination angle When the inclination angle is 18ndash27deg and thegroup stress is 10MPa the roadwayrsquos high side is 15ndash10mm
larger than the low side e main reason is that the dif-ference in height between the two walls leads to unevenstress distribution
5 Validation of the Simulation Test
51 Test Plan To verify the asymmetric stress distributioncharacteristics of the surrounding rock of the right-angledtrapezoidal roadway in the inclined seam further the lab-oratory model test adopted the principle of geometricsimilarity and strength equality and established four types ofright-angled trapezoidal roadway test models with differentinclined seam angles namely 18deg 21deg 24deg and 27deg
Table 2 Distance from peak stress concentration to both sides of roadway (mm)
Dip angleGround stress 10MPa Ground stress 20MPa
Low side High side Low side High side18deg 642 514 1203 106721deg 605 405 1185 98524deg 54 29 1118 83827deg 501 201 1055 665
70522E + 0570000E + 0560000E + 0550000E + 0540000E + 0530000E + 0520000E + 0510000E + 0500000E + 00ndash10000E + 05ndash20000E + 05ndash30000E + 05ndash40000E + 05ndash50000E + 05ndash60000E + 05ndash70000E + 05ndash80000E + 05ndash90000E + 05ndash90594E + 05
Stress (Pa)
(a)
94567E + 0580000E + 0560000E + 0540000E + 0520000E + 0500000E + 00ndash20000E + 05ndash40000E + 05ndash60000E + 05ndash80000E + 05ndash10000E + 06ndash11309E + 06
Stress (Pa)
(b)
ndash10000E + 05ndash20000E + 05ndash30000E + 05ndash40000E + 05ndash50000E + 05ndash60000E + 05ndash70000E + 05ndash76621E + 05
39580E + 0530000E + 0520000E + 0510000E + 0500000E + 00
Stress (Pa)
(c)
ndash10000E + 05ndash20000E + 05ndash30000E + 05ndash40000E + 05ndash50000E + 05ndash60000E + 05ndash64765E + 05
39675E + 0530000E + 0520000E + 0510000E + 0500000E + 00
Stress (Pa)
(d)
Figure 8 Horizontal stress distribution characteristics of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
6 Advances in Civil Engineering
Displacement (m)
ndash50000E ndash 04ndash10000E ndash 03ndash15000E ndash 03ndash20000E ndash 03ndash22092E ndash 03
35007E ndash 03
30000E ndash 0335000E ndash 03
25000E ndash 0320000E ndash 0315000E ndash 0310000E ndash 0350000E ndash 0400000E + 00
(a)
Displacement (m)
ndash25000E ndash 04ndash50000E ndash 04ndash75000E ndash 04ndash10000E ndash 03ndash12500E ndash 03ndash12767E ndash 03
20000E ndash 0321873E ndash 03
15000E ndash 0317500E ndash 03
12500E ndash 0310000E ndash 0375000E ndash 0450000E ndash 0425000E ndash 0400000E + 00
(b)
Displacement (m)
ndash25000E ndash 04ndash50000E ndash 04ndash75000E ndash 04ndash10000E ndash 03ndash12500E ndash 03ndash15000E ndash 03ndash17500E ndash 03ndash18776E ndash 03
20000E ndash 03
15000E ndash 0317500E ndash 03
12500E ndash 0310000E ndash 03
26609E ndash 0325000E ndash 0322500E ndash 03
75000E ndash 0450000E ndash 0425000E ndash 0400000E + 00
(c)
Displacement (m)
ndash25000E ndash 04ndash50000E ndash 04ndash75000E ndash 04ndash10000E ndash 03ndash10040E ndash 03
15000E ndash 0316911E ndash 03
12500E ndash 0310000E ndash 0375000E ndash 0450000E ndash 0425000E ndash 0400000E + 00
(d)
Figure 9 Horizontal stress distribution characteristics of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
0 3 6 9 12 15 18 21 240
30
60
90
120
150
180
210
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)
(a)
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)0 3 6 9 12 15 18 21 24
0
30
60
90
120
150
180
(b)
Figure 10 Continued
Advances in Civil Engineering 7
(Figure 11)e geometric similarity ratio is 1 30 the modelsize is 72 cmtimes 72 cmtimes 10 cm and the lithology parametersare selected from the engineering background of the Shi-tanjing No 2 mining area which is the same as that for thenumerical simulation Different proportions of cementmortar were used to simulate the characteristics
e measurement points are arranged at the roadwaywalls roof and floor as well as the corners A verticaluniform load is applied to the model in a stepwise manneruntil the specimen is completely destroyede strain valuesof each measurement point under different loads arerecorded in real time during the loading process
52 Analysis of Test Results
521 Stress Distribution Law of the Roof Surrounding theRock Figure 12 displays a simulated ground stress-straincurve of the roof surrounding the rock of the trapezoidalroadway with different dip angles e stress of the roofsurrounding the rock of the roadway presents obviousasymmetric characteristics and the size distribution of themiddle measuring point of the roof (Intermediate)gt the lowside measuring point of the roof (R- low side)gt the high sidemeasuring point of the roof (R- high side) from Figure 12 Inaddition the maximum strain on the low side of the sur-rounding rock is significantly larger than that on the highside e greater the dip angle the more obvious the dif-ference in stress distribution between the high and low sides
of the surrounding rock of the roadway When the incli-nation angle is in the range of 18degndash27deg the maximum strainon the right wall of the roof (R- low side) is 13ndash21 timeslarger than that on the left wall of the roof (R- high side)
522 Stress Distribution Law of the Surrounding Rocks of theTwo Walls of the Roadway Figure 13 describes the simu-lated ground stress-strain curve of the surrounding rock ofthe right-angled trapezoidal roadway with different dipangles It can be concluded that the stress concentrations onthe two walls of the roadway are clearly different and theyincrease with increasing inclination and ground stress einclination angle is 18degndash27deg and the maximum value of theright wall (low side) stress concentration is 12ndash17 times thatof the left wall (high side)
523 Stress Distribution Law of the Two Surrounding RocksFigure 14 is a simulated ground stress-strain curve of thesurrounding rock at the corners of a right-angled trapezoidalroadway with different dip angles Figure 14 reveals that thestress distribution of each point at the four corners of theroadway is different From large to small the order is lowside shoulder angle (LSSA) high side shoulder angle(HSSA) low side bottom angle (LSBA) and high sidebottom angle (HSBA) When the dip angle is 18deg LSSArsquosstrain is 2ndash4 times of other sharp angles it changes with thechange in inclination
524 Analysis of Stress Distribution in the Surrounding Rockof the Roadway Floor Figure 15 is a simulated groundstress-strain curve of the surrounding rock of a rectangulartrapezoidal roadway with different dip angles It can be seenfrom Figure 15 that under the action of the upper roof andthe two sets of asymmetric stress the stress distribution ofthe floor of the roadway also exhibits obvious asymmetry
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)0 3 6 9 12 15 18 21 24
0
20
40
60
80
100
120
(c)
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)0 3 6 9 12 15 18 21 24
0
10
20
30
40
50
60
(d)
Figure 10 Analysis curves of the horizontal displacements of the two sides of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Table 3 Horizontal displacement of two sides of roadway (mm)
Dip angleGround stress 10MPa Ground stress 20MPaLow side High side Low side High side
18deg 2254 3747 11551 1925321deg 2389 3131 11464 1590024deg 1493 2301 7288 1068927deg 71 17 2141 5881
8 Advances in Civil Engineering
Data analysis
Computer
Strain gauge
Monitoring point
Loading
07m 01m
072
m
015m
01m
R-high side R-low sideIntermediate
LSSAHSSA
LSBAHSBA
High sideLow side
F-high side F-low side
Figure 11 Test models of the right-angled trapezoidal roadway
0
1
2
3
4
5
6
7
8
0 25 50 75 100 125 150 175Strain (10ndash6)
Stre
ss (M
Pa)
R-high sideIntermediateR-low side
(a)
Strain (10ndash6)
Stre
ss (M
Pa)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
7
0 30 60 90 120 150 180 210
(b)
Stre
ss (M
Pa)
Strain (10ndash6)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
0 40 80 120 160 200 240 280
(c)
Stre
ss (M
Pa)
Strain (10ndash6)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
0 50 100 150 200 250 300 350
(d)
Figure 12 Stress-strain curves of the roof surrounding the rock (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Advances in Civil Engineering 9
0
1
2
3
4
5
6
7
8
0 600 1200 1800 2400 3000
High sideLow side
Stre
ss (M
Pa)
Strain (10ndash6)
(a)
High sideLow side
0
1
2
3
4
5
6
7
0 300 600 900 1200 1500 1800
Stre
ss (M
Pa)
Strain (10ndash6)
(b)
0
1
2
3
4
5
6
0 800 1600 2400 3200
Stre
ss (M
Pa)
High sideLow side
Strain (10ndash6)
(c)
Stre
ss (M
Pa)
0
1
2
3
4
5
0 500 1000 1500 2000 2500
High sideLow side
Strain (10ndash6)
(d)
Figure 13 Stress-strain curve of the surrounding rock of the two sides of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
0
1
2
3
4
5
6
7
8
0 150 300 450 600 750 900
Stre
ss (M
Pa)
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(a)
Stre
ss (M
Pa)
0
1
2
3
4
5
6
7
0 200 400 600 800 1000 1200 1400
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(b)
Figure 14 Continued
10 Advances in Civil Engineering
Stre
ss (M
Pa)
0
1
2
3
4
5
6
0 200 400 600 800 1000 1200
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(c)
Stre
ss (M
Pa)
0
1
2
3
4
5
0 200 400 600 800 1000 1200 1400
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(d)
Figure 14 Stress-strain curve of the surrounding rock at the corner of the roadway (a) 18deg (b) 21deg (c) 27deg (d) 27deg
F-high sideF-low side
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
Stre
ss (M
Pa)
Strain (10ndash6)
(a)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
6
7
0 20 40 60 80 100 120 140 160Strain (10ndash6)
(b)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
6
0 30 60 90 120 150 180Strain (10ndash6)
(c)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
0 25 50 75 100 125Strain (10ndash6)
(d)
Figure 15 Stress-strain curve of roadway floor (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Advances in Civil Engineering 11
and the stress on the right wall of the floor (F-low side) isgreater than that on the left wall of the floor (F-high side)
From the laboratory model test results it can be seen thatthe stress distribution law of the right-angled trapezoidalroadway in a gently inclined seam is similar to the numericalsimulation and the stress distribution of the surroundingrock in the roof the two walls the floor and the corner of theroadway shows clear asymmetric characteristics howeverthere are some differences in the numerical valuese mainreason is that the proportion of similar materials size of themodel loading mode and so on have an impact on the testresults
6 Comparison and Analysis ofSimulation Results
It can be seen from the simulation results that the asym-metric distribution law of the surrounding rock in inclinedright angle trapezoidal roadway is basically the same as thatof large dip angle and steep inclined coal seam roadway butthe degree of stress asymmetry in the inclined coal seam ismuch lower than that of large dip angle coal seam enumerical simulation results of the asymmetric deformationand failure characteristics of the inclined trapezoidal
roadway in the inclined coal seam are consistent with thelaboratory model test (Figure 16) and the site failuremorphology of the Shitanjing No 2 mine (Figure 17) inwhich the deformation and failure law exhibits an asym-metrical feature Further the two walls of the roadway areseverely bulging and the low side is larger than the high side
7 Conclusion
Based on the theory of asymmetric stress distribution in thesurrounding rock of right-angled trapezoidal roadway in aninclined coal seam and considering the Shijiajing No 2mining area as the engineering background this paperfurther analyzes the asymmetric distribution characteristicsof the surrounding rock by using the FLAC3D finite dif-ference method rough verifications with a simulationtest the following conclusions were drawn
(1) e stress distribution of the surrounding rock of theright-angled trapezoidal roadway in the inclined coalseam shows clear asymmetryemain performanceis that the peak value of stress concentration in thelow side is greater than that in the high side and thedistance between the high side and the side wall ofthe roadway is greater than that in the low side With
(a) (b)
Figure 16 Deformation and failure of roadway in laboratory model test (a) 24deg (b) 27deg
(a) (b)
Figure 17 Deformation and failure of roadway in Shitanjing No 2 mine (a) 24deg (b) 27deg
12 Advances in Civil Engineering
the increase in the inclination angle and groundstress the difference between the peak value of stressconcentration and the distance from the side wall ofthe roadway is more obvious When the inclinationangle is 18degndash27deg the peak value of stress concen-tration of the low side is 107ndash133 times that of thehigh side and the distance from the high side to theside wall of the roadway is 126ndash379m larger thanthat of the low side Second two sharp corners thatare symmetric with the same inclination angle of thecoal seam show obvious compressive stress regionswhile the opposite two sharp corners show obvioustensile stress regions e maximum values ofcompressive and tensile stresses appear on the roof ofthe roadway
(2) Under the action of asymmetric stress the defor-mation and failure of the roadway surrounding therock also presents asymmetric characteristics etwo walls of the roadway exhibit extrusion dislo-cation and serious deformation and damage how-ever the deformation damage of the low side isobviously larger than that at the high side e mainreason is that the difference in height between thetwo walls of the roadway leads to the uneven dis-tribution of stress
(3) e results of numerical simulation are basicallyconsistent with laboratory model test and field en-gineering However there are some differences in thedata obtained and the main reason is that the two areaffected by the selection of the simulation parame-ters ratio of similar materials size of the model andloading method
Data Availability
e data used to support the findings of this study are in-cluded within the article
Conflicts of Interest
e authors declare that they have no conflicts of interestregarding the publication of this paper
Acknowledgments
is study was financially supported by the National NaturalScience Foundation of China (51174159 and 59974019) theChina Postdoctoral Science Foundation (2015M572580)and the Scientific Research Plan Projects of EducationDepartment of Shanxi Province of China (15JK1471)
Supplementary Materials
eoretical analysis process of roof stress distribution ininclined coal seam roadway (Supplementary Materials)
References
[1] H C Li ldquoStudy on deformation and failure characteristicsand stability control of large dip angle thick compound roofroadwayrdquo Dissertation Taiyuan University of TechnologyTaiyuan China 2014
[2] e National Development and Reform Commission PeoplersquosRepublic of China Energy Development 11th Five-Year PlanBeijing China 2007 in Chinese
[3] K Yu L Zhou Q Cao and Z Li ldquoEvolutionary game re-search on symmetry of workersrsquo behavior in coal mine en-terprisesrdquo Symmetry vol 11 no 2 pp 156ndash168 2019
[4] L Si Z Wang R Xu C Tan X Liu and J Xu ldquoImageenhancement for surveillance video of coal mining face basedon single-scale retinex algorithm combined with bilateralfilteringrdquo Symmetry vol 9 no 6 pp 93ndash108 2017
[5] F L He M G Qian and C Y Liu Support System of Supportand Surrounding Rock for High Productivity and High Effi-ciency Working Face China Mining Industry Press XuzhouChina 1997 in Chinese
[6] S J Chen Y Wang Y Z Wu Z Wang and W J ZhangldquoCoal resources and development potential in northwestChinardquo Northwestern Geology vol 4 pp 40ndash56 2006 inChinese
[7] X M Sun and M C He ldquoNumerical simulation research oncoupling support theory of roadway within soft rock atdepthrdquo Journal of China University of Mining and Technologyvol 34 no 2 pp 166ndash169 2005 in Chinese
[8] S X Wei J H Song and H W Jing ldquoNumerical analysis ofstress in the surrounding rock of the dynamic pressure tunnelwith inclined seamsrdquo Metal Mine vol 41 no 3 pp 37ndash412012 in Chinese
[9] H Wang B Xia Y Lu T Gong and R Zhang ldquoStudy on thepropagation laws of hydrofractures meeting a faulted struc-ture in the coal seamrdquo Energies vol 10 no 5 pp 654ndash6722017
[10] J Xie J Xu and FWang ldquoMining-induced stress distributionof the working face in a kilometer-deep coal mine-a case studyin Tangshan coal minerdquo Journal of Geophysics and Engi-neering vol 15 no 5 pp 2060ndash2070 2018
[11] S Zhang X Wang G Fan D Zhang and C Jianbin ldquoPillarsize optimization design of isolated island panel gob-sideentry driving in deep inclined coal seam-case study ofPingmei No 6 coal seamrdquo Journal of Geophysics and Engi-neering vol 15 no 3 pp 816ndash828 2018
[12] Y Yuan S Tu F Wang X Zhang and B Li ldquoHydraulicsupport instability mechanism and its control in a fully-mechanized steep coal seam working face with large miningheightrdquo Journal of the Southern African Institute of Miningand Metallurgy vol 115 no 5 pp 441ndash447 2015
[13] J Sun L Wang and G Zhao ldquoFailure characteristics andconfined permeability of an inclined coal seam floor in fluid-solid couplingrdquo Advances in Civil Engineering vol 2018Article ID 2356390 12 pages 2018
[14] S Gu B Jiang G Wang H Dai and M Zhang ldquoOccurrencemechanism of roof-fall accidents in large-section coal seamroadways and related support design for Bayangaole coalmine Chinardquo Advances in Civil Engineering vol 2018 ArticleID 6831731 17 pages 2018
[15] H Xie M Gao R Zhang G Peng W Wang and A LildquoStudy on the mechanical properties andmechanical response
Advances in Civil Engineering 13
of coal mining at 1000m or deeperrdquo RockMechanics and RockEngineering vol 52 no 5 pp 1475ndash1490 2019
[16] Y Fang C Xu G Cui and B Kenneally ldquoScale model test ofhighway tunnel construction underlying mined-out thin coalseamrdquo Tunnelling and Underground Space Technology vol 56pp 105ndash116 2016
[17] M C He ldquoPhysical modeling of an underground roadwayexcavation in geologically 45deg inclined rock using infraredthermographyrdquo Engineering Geology vol 121 no 3-4pp 165ndash176 2011
[18] W Gong Y Peng M He and J Wang ldquoermal image andspectral characterization of roadway failure process in geo-logically 45deg inclined rocksrdquo Tunnelling and UndergroundSpace Technology vol 49 pp 156ndash173 2015
[19] H Yang S Cao Y Li C Sun and P Guo ldquoSoft roof failuremechanism and supporting method for gob-side entryretainingrdquo Minerals vol 5 no 4 pp 707ndash722 2015
[20] L Q Ma Y Zhang D S Zhang X Q Cao Q Q Li andY B Zhang ldquoSupport stability mechanism in a coal face withlarge angles in both strike and diprdquo Journal of the SouthernAfrican Institute of Mining and Metallurgy vol 115 no 7pp 599ndash606 2015
[21] M Jawed and R K Sinha ldquoDesign of rhombus coal pillars andsupport for roadway stability and mechanizing loading of facecoal using SDLs in a steeply inclined thin coal seammdashatechnical feasibility studyrdquo Arabian Journal of Geosciencesvol 11 no 15 pp 415ndash429 2018
[22] Y Yin J Zou Y Zhang Y Qiu and K Fang ldquoExperimentalstudy of the movement of backfilling gangues for goaf insteeply inclined coal seamsrdquo Arabian Journal of Geosciencesvol 11 no 12 pp 318ndash326 2018
[23] L Q Zhu and Y Zhang ldquoAnalysis of spontaneous com-bustion ldquothree zonesrdquo in 3237 working face of zhaogezhuangminerdquo Applied Mechanics and Materials vol 71ndash78pp 1978ndash1982 2011
[24] S Q He D Z Song Z L Li et al ldquoPrecursor of spatio-temporal evolution law of MS and AE activities for rock burstwarning in steeply inclined and extremely thick coal seamsunder caving mining conditionsrdquo Rock Mechanics and RockEngineering no 2 pp 1ndash21 2019
[25] H S Tu S H Tu Y Yuan F T Wang and Q S Bai ldquoPresentsituation of fully mechanized mining technology for steeplyinclined coal seams in Chinardquo Arabian Journal of Geosciencesvol 8 no 7 pp 1978ndash1982 2015
[26] W Lv Y Wu L Ming and J Yin ldquoMigration law of the roofof a composited backfilling longwall face in a steeply dippingcoal seamrdquo Minerals vol 9 no 3 pp 188ndash203 2019
[27] Z Bei S G Cao L G Wang and Y L Lu ldquoDeformationfailure mechanism and support measurements in roadway ofsteeply inclined coal seamrdquo Journal of Mining amp Safety En-gineering vol 28 no 2 pp 214ndash219 2011
[28] M Z Gao and H Q Jing ldquoMechanical analysis of asymmetricfloor heave of roadwayrdquo Journal of Anhui University of Scienceand Technology vol 32 no 4 pp 38ndash43 2012 in Chinese
[29] J G Liu A Y Cao Z M Yu G C Jing and H Y Liu ldquoStudyon stress characteristics of roadwayrsquos sides in deep and in-clined seamrdquo China Coal vol 42 no 8 pp 30ndash34 2016 inChinese
[30] X H Qi ldquoStudy on deformation characters and supportparameters of large angle seam roadway rock aroundrdquo Dis-sertation Xirsquoan University of Science and Technology XirsquoanChina 2015 in chinese
14 Advances in Civil Engineering
Table 1 Numerical simulation of physical and mechanical parameters of coal and rock
Rock stratum ickness(m)
Density(kgmiddotmminus3)
Bulk modulus(GPa)
Shear modulus(GPa)
Friction(deg)
Cohesion(MPa)
Tension(MPa)
(1) Siltstone 46 2 460 849 647 321 57 377(2) Medium grainsandstone 4 2 510 1011 727 370 118 278
(3) Mudstone 29 2 530 779 534 315 185 154(4) Coal seam 55 1 400 180 083 210 160 050(5) Siltstone 92 2 460 849 647 321 57 377
Stress (Pa)ndash48069E + 05ndash50000E + 05ndash75000E + 05ndash10000E + 06ndash12500E + 06ndash15000E + 06ndash17500E + 06ndash20000E + 06ndash22500E + 06ndash25000E + 06ndash27500E + 06ndash30000E + 06ndash32500E + 06ndash35000E + 06ndash37500E + 06ndash40000E + 06ndash42500E + 06ndash43232E + 06
(a)
Stress (Pa)99217E + 0400000E + 00ndash25000E + 05ndash50000E + 05ndash75000E + 05ndash10000E + 06ndash12500E + 06ndash15000E + 06ndash17500E + 06ndash20000E + 06ndash22500E + 06ndash25000E + 06ndash27500E + 06ndash30000E + 06ndash32500E + 06ndash35000E + 06
ndash42500E + 06ndash45000E + 06ndash45879E + 06
ndash37500E + 06ndash40000E + 06
(b)
Stress (Pa)ndash12397E + 06ndash12500E + 06ndash15000E + 06ndash17500E + 06ndash20000E + 06ndash22500E + 06ndash25000E + 06ndash27500E + 06ndash30000E + 06ndash32500E + 06ndash35000E + 06ndash37500E + 06ndash40000E + 06ndash40781E + 06
(c)
Stress (Pa)ndash17537E + 06ndash18000E + 06ndash20000E + 06ndash22000E + 06ndash24000E + 06ndash26000E + 06ndash28000E + 06ndash30000E + 06ndash32000E + 06
ndash38000E + 06ndash40000E + 06ndash40627E + 06
ndash34000E + 06ndash36000E + 06
(d)
Figure 5 Vertical stress nephogram of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
36m
3m
36m
5m
45m
18deg21deg24deg27deg
SiltstoneMedium grain sandstoneMudstoneCoal seam
Siltstone
Roadway
Figure 4 Numerical calculation model
4 Advances in Civil Engineering
0 3 6 9 12 15 18 21 240
5
10
15
20
25
30
35
40
High sideLow side
Stre
ss (M
Pa)
q (MPa)
(a)
High sideLow side
q (MPa)0 3 6 9 12 15 18 21 24
0
5
10
15
20
25
30
35
40
45
Stre
ss (M
Pa)
(b)
High sideLow side
q (MPa)0 3 6 9 12 15 18 21 24
0
5
10
15
20
25
30
35
40
Stre
ss (M
Pa)
(c)
High sideLow side
q (MPa)0 3 6 9 12 15 18 21 24
0
5
10
15
20
25
30
35
40
Stre
ss (M
Pa)
(d)
Figure 6 Comparative analysis curves of peak stress and ground stress of the two sides of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
15 18 21 24 27 300
3
6
9
12
Dip angle (deg)
High sideLow side
Dist
ance
(m)
(a)
Dip angle (deg)
High sideLow side
Dist
ance
(m)
15 18 21 24 27 303
6
9
12
15
(b)
Figure 7 Curve of the change in stress concentration peak with the side distance of the two sides of the roadway with inclination angle (a)10MPa (b) 20MPa
Advances in Civil Engineering 5
43 Horizontal Displacement Characteristics of the RoadwayFigures 9 and 10 depict the horizontal stress nephogram ofthe roadway and the displacement analysis diagram of thetwo walls of the roadway with different simulated groundstresses q and different inclination angles respectivelyFigures 9 and 10 and Table 3 reveal that the displacementdifference between the two walls of the roadway is obviousand increases with the increase in group stress e groupstress is 10ndash15MPa and the inclination angle is 18deg and theroadwayrsquos high side is 15ndash77mm larger than the low sideHowever the difference decreases with the increase in in-clination angle When the inclination angle is 18ndash27deg and thegroup stress is 10MPa the roadwayrsquos high side is 15ndash10mm
larger than the low side e main reason is that the dif-ference in height between the two walls leads to unevenstress distribution
5 Validation of the Simulation Test
51 Test Plan To verify the asymmetric stress distributioncharacteristics of the surrounding rock of the right-angledtrapezoidal roadway in the inclined seam further the lab-oratory model test adopted the principle of geometricsimilarity and strength equality and established four types ofright-angled trapezoidal roadway test models with differentinclined seam angles namely 18deg 21deg 24deg and 27deg
Table 2 Distance from peak stress concentration to both sides of roadway (mm)
Dip angleGround stress 10MPa Ground stress 20MPa
Low side High side Low side High side18deg 642 514 1203 106721deg 605 405 1185 98524deg 54 29 1118 83827deg 501 201 1055 665
70522E + 0570000E + 0560000E + 0550000E + 0540000E + 0530000E + 0520000E + 0510000E + 0500000E + 00ndash10000E + 05ndash20000E + 05ndash30000E + 05ndash40000E + 05ndash50000E + 05ndash60000E + 05ndash70000E + 05ndash80000E + 05ndash90000E + 05ndash90594E + 05
Stress (Pa)
(a)
94567E + 0580000E + 0560000E + 0540000E + 0520000E + 0500000E + 00ndash20000E + 05ndash40000E + 05ndash60000E + 05ndash80000E + 05ndash10000E + 06ndash11309E + 06
Stress (Pa)
(b)
ndash10000E + 05ndash20000E + 05ndash30000E + 05ndash40000E + 05ndash50000E + 05ndash60000E + 05ndash70000E + 05ndash76621E + 05
39580E + 0530000E + 0520000E + 0510000E + 0500000E + 00
Stress (Pa)
(c)
ndash10000E + 05ndash20000E + 05ndash30000E + 05ndash40000E + 05ndash50000E + 05ndash60000E + 05ndash64765E + 05
39675E + 0530000E + 0520000E + 0510000E + 0500000E + 00
Stress (Pa)
(d)
Figure 8 Horizontal stress distribution characteristics of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
6 Advances in Civil Engineering
Displacement (m)
ndash50000E ndash 04ndash10000E ndash 03ndash15000E ndash 03ndash20000E ndash 03ndash22092E ndash 03
35007E ndash 03
30000E ndash 0335000E ndash 03
25000E ndash 0320000E ndash 0315000E ndash 0310000E ndash 0350000E ndash 0400000E + 00
(a)
Displacement (m)
ndash25000E ndash 04ndash50000E ndash 04ndash75000E ndash 04ndash10000E ndash 03ndash12500E ndash 03ndash12767E ndash 03
20000E ndash 0321873E ndash 03
15000E ndash 0317500E ndash 03
12500E ndash 0310000E ndash 0375000E ndash 0450000E ndash 0425000E ndash 0400000E + 00
(b)
Displacement (m)
ndash25000E ndash 04ndash50000E ndash 04ndash75000E ndash 04ndash10000E ndash 03ndash12500E ndash 03ndash15000E ndash 03ndash17500E ndash 03ndash18776E ndash 03
20000E ndash 03
15000E ndash 0317500E ndash 03
12500E ndash 0310000E ndash 03
26609E ndash 0325000E ndash 0322500E ndash 03
75000E ndash 0450000E ndash 0425000E ndash 0400000E + 00
(c)
Displacement (m)
ndash25000E ndash 04ndash50000E ndash 04ndash75000E ndash 04ndash10000E ndash 03ndash10040E ndash 03
15000E ndash 0316911E ndash 03
12500E ndash 0310000E ndash 0375000E ndash 0450000E ndash 0425000E ndash 0400000E + 00
(d)
Figure 9 Horizontal stress distribution characteristics of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
0 3 6 9 12 15 18 21 240
30
60
90
120
150
180
210
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)
(a)
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)0 3 6 9 12 15 18 21 24
0
30
60
90
120
150
180
(b)
Figure 10 Continued
Advances in Civil Engineering 7
(Figure 11)e geometric similarity ratio is 1 30 the modelsize is 72 cmtimes 72 cmtimes 10 cm and the lithology parametersare selected from the engineering background of the Shi-tanjing No 2 mining area which is the same as that for thenumerical simulation Different proportions of cementmortar were used to simulate the characteristics
e measurement points are arranged at the roadwaywalls roof and floor as well as the corners A verticaluniform load is applied to the model in a stepwise manneruntil the specimen is completely destroyede strain valuesof each measurement point under different loads arerecorded in real time during the loading process
52 Analysis of Test Results
521 Stress Distribution Law of the Roof Surrounding theRock Figure 12 displays a simulated ground stress-straincurve of the roof surrounding the rock of the trapezoidalroadway with different dip angles e stress of the roofsurrounding the rock of the roadway presents obviousasymmetric characteristics and the size distribution of themiddle measuring point of the roof (Intermediate)gt the lowside measuring point of the roof (R- low side)gt the high sidemeasuring point of the roof (R- high side) from Figure 12 Inaddition the maximum strain on the low side of the sur-rounding rock is significantly larger than that on the highside e greater the dip angle the more obvious the dif-ference in stress distribution between the high and low sides
of the surrounding rock of the roadway When the incli-nation angle is in the range of 18degndash27deg the maximum strainon the right wall of the roof (R- low side) is 13ndash21 timeslarger than that on the left wall of the roof (R- high side)
522 Stress Distribution Law of the Surrounding Rocks of theTwo Walls of the Roadway Figure 13 describes the simu-lated ground stress-strain curve of the surrounding rock ofthe right-angled trapezoidal roadway with different dipangles It can be concluded that the stress concentrations onthe two walls of the roadway are clearly different and theyincrease with increasing inclination and ground stress einclination angle is 18degndash27deg and the maximum value of theright wall (low side) stress concentration is 12ndash17 times thatof the left wall (high side)
523 Stress Distribution Law of the Two Surrounding RocksFigure 14 is a simulated ground stress-strain curve of thesurrounding rock at the corners of a right-angled trapezoidalroadway with different dip angles Figure 14 reveals that thestress distribution of each point at the four corners of theroadway is different From large to small the order is lowside shoulder angle (LSSA) high side shoulder angle(HSSA) low side bottom angle (LSBA) and high sidebottom angle (HSBA) When the dip angle is 18deg LSSArsquosstrain is 2ndash4 times of other sharp angles it changes with thechange in inclination
524 Analysis of Stress Distribution in the Surrounding Rockof the Roadway Floor Figure 15 is a simulated groundstress-strain curve of the surrounding rock of a rectangulartrapezoidal roadway with different dip angles It can be seenfrom Figure 15 that under the action of the upper roof andthe two sets of asymmetric stress the stress distribution ofthe floor of the roadway also exhibits obvious asymmetry
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)0 3 6 9 12 15 18 21 24
0
20
40
60
80
100
120
(c)
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)0 3 6 9 12 15 18 21 24
0
10
20
30
40
50
60
(d)
Figure 10 Analysis curves of the horizontal displacements of the two sides of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Table 3 Horizontal displacement of two sides of roadway (mm)
Dip angleGround stress 10MPa Ground stress 20MPaLow side High side Low side High side
18deg 2254 3747 11551 1925321deg 2389 3131 11464 1590024deg 1493 2301 7288 1068927deg 71 17 2141 5881
8 Advances in Civil Engineering
Data analysis
Computer
Strain gauge
Monitoring point
Loading
07m 01m
072
m
015m
01m
R-high side R-low sideIntermediate
LSSAHSSA
LSBAHSBA
High sideLow side
F-high side F-low side
Figure 11 Test models of the right-angled trapezoidal roadway
0
1
2
3
4
5
6
7
8
0 25 50 75 100 125 150 175Strain (10ndash6)
Stre
ss (M
Pa)
R-high sideIntermediateR-low side
(a)
Strain (10ndash6)
Stre
ss (M
Pa)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
7
0 30 60 90 120 150 180 210
(b)
Stre
ss (M
Pa)
Strain (10ndash6)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
0 40 80 120 160 200 240 280
(c)
Stre
ss (M
Pa)
Strain (10ndash6)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
0 50 100 150 200 250 300 350
(d)
Figure 12 Stress-strain curves of the roof surrounding the rock (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Advances in Civil Engineering 9
0
1
2
3
4
5
6
7
8
0 600 1200 1800 2400 3000
High sideLow side
Stre
ss (M
Pa)
Strain (10ndash6)
(a)
High sideLow side
0
1
2
3
4
5
6
7
0 300 600 900 1200 1500 1800
Stre
ss (M
Pa)
Strain (10ndash6)
(b)
0
1
2
3
4
5
6
0 800 1600 2400 3200
Stre
ss (M
Pa)
High sideLow side
Strain (10ndash6)
(c)
Stre
ss (M
Pa)
0
1
2
3
4
5
0 500 1000 1500 2000 2500
High sideLow side
Strain (10ndash6)
(d)
Figure 13 Stress-strain curve of the surrounding rock of the two sides of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
0
1
2
3
4
5
6
7
8
0 150 300 450 600 750 900
Stre
ss (M
Pa)
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(a)
Stre
ss (M
Pa)
0
1
2
3
4
5
6
7
0 200 400 600 800 1000 1200 1400
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(b)
Figure 14 Continued
10 Advances in Civil Engineering
Stre
ss (M
Pa)
0
1
2
3
4
5
6
0 200 400 600 800 1000 1200
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(c)
Stre
ss (M
Pa)
0
1
2
3
4
5
0 200 400 600 800 1000 1200 1400
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(d)
Figure 14 Stress-strain curve of the surrounding rock at the corner of the roadway (a) 18deg (b) 21deg (c) 27deg (d) 27deg
F-high sideF-low side
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
Stre
ss (M
Pa)
Strain (10ndash6)
(a)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
6
7
0 20 40 60 80 100 120 140 160Strain (10ndash6)
(b)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
6
0 30 60 90 120 150 180Strain (10ndash6)
(c)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
0 25 50 75 100 125Strain (10ndash6)
(d)
Figure 15 Stress-strain curve of roadway floor (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Advances in Civil Engineering 11
and the stress on the right wall of the floor (F-low side) isgreater than that on the left wall of the floor (F-high side)
From the laboratory model test results it can be seen thatthe stress distribution law of the right-angled trapezoidalroadway in a gently inclined seam is similar to the numericalsimulation and the stress distribution of the surroundingrock in the roof the two walls the floor and the corner of theroadway shows clear asymmetric characteristics howeverthere are some differences in the numerical valuese mainreason is that the proportion of similar materials size of themodel loading mode and so on have an impact on the testresults
6 Comparison and Analysis ofSimulation Results
It can be seen from the simulation results that the asym-metric distribution law of the surrounding rock in inclinedright angle trapezoidal roadway is basically the same as thatof large dip angle and steep inclined coal seam roadway butthe degree of stress asymmetry in the inclined coal seam ismuch lower than that of large dip angle coal seam enumerical simulation results of the asymmetric deformationand failure characteristics of the inclined trapezoidal
roadway in the inclined coal seam are consistent with thelaboratory model test (Figure 16) and the site failuremorphology of the Shitanjing No 2 mine (Figure 17) inwhich the deformation and failure law exhibits an asym-metrical feature Further the two walls of the roadway areseverely bulging and the low side is larger than the high side
7 Conclusion
Based on the theory of asymmetric stress distribution in thesurrounding rock of right-angled trapezoidal roadway in aninclined coal seam and considering the Shijiajing No 2mining area as the engineering background this paperfurther analyzes the asymmetric distribution characteristicsof the surrounding rock by using the FLAC3D finite dif-ference method rough verifications with a simulationtest the following conclusions were drawn
(1) e stress distribution of the surrounding rock of theright-angled trapezoidal roadway in the inclined coalseam shows clear asymmetryemain performanceis that the peak value of stress concentration in thelow side is greater than that in the high side and thedistance between the high side and the side wall ofthe roadway is greater than that in the low side With
(a) (b)
Figure 16 Deformation and failure of roadway in laboratory model test (a) 24deg (b) 27deg
(a) (b)
Figure 17 Deformation and failure of roadway in Shitanjing No 2 mine (a) 24deg (b) 27deg
12 Advances in Civil Engineering
the increase in the inclination angle and groundstress the difference between the peak value of stressconcentration and the distance from the side wall ofthe roadway is more obvious When the inclinationangle is 18degndash27deg the peak value of stress concen-tration of the low side is 107ndash133 times that of thehigh side and the distance from the high side to theside wall of the roadway is 126ndash379m larger thanthat of the low side Second two sharp corners thatare symmetric with the same inclination angle of thecoal seam show obvious compressive stress regionswhile the opposite two sharp corners show obvioustensile stress regions e maximum values ofcompressive and tensile stresses appear on the roof ofthe roadway
(2) Under the action of asymmetric stress the defor-mation and failure of the roadway surrounding therock also presents asymmetric characteristics etwo walls of the roadway exhibit extrusion dislo-cation and serious deformation and damage how-ever the deformation damage of the low side isobviously larger than that at the high side e mainreason is that the difference in height between thetwo walls of the roadway leads to the uneven dis-tribution of stress
(3) e results of numerical simulation are basicallyconsistent with laboratory model test and field en-gineering However there are some differences in thedata obtained and the main reason is that the two areaffected by the selection of the simulation parame-ters ratio of similar materials size of the model andloading method
Data Availability
e data used to support the findings of this study are in-cluded within the article
Conflicts of Interest
e authors declare that they have no conflicts of interestregarding the publication of this paper
Acknowledgments
is study was financially supported by the National NaturalScience Foundation of China (51174159 and 59974019) theChina Postdoctoral Science Foundation (2015M572580)and the Scientific Research Plan Projects of EducationDepartment of Shanxi Province of China (15JK1471)
Supplementary Materials
eoretical analysis process of roof stress distribution ininclined coal seam roadway (Supplementary Materials)
References
[1] H C Li ldquoStudy on deformation and failure characteristicsand stability control of large dip angle thick compound roofroadwayrdquo Dissertation Taiyuan University of TechnologyTaiyuan China 2014
[2] e National Development and Reform Commission PeoplersquosRepublic of China Energy Development 11th Five-Year PlanBeijing China 2007 in Chinese
[3] K Yu L Zhou Q Cao and Z Li ldquoEvolutionary game re-search on symmetry of workersrsquo behavior in coal mine en-terprisesrdquo Symmetry vol 11 no 2 pp 156ndash168 2019
[4] L Si Z Wang R Xu C Tan X Liu and J Xu ldquoImageenhancement for surveillance video of coal mining face basedon single-scale retinex algorithm combined with bilateralfilteringrdquo Symmetry vol 9 no 6 pp 93ndash108 2017
[5] F L He M G Qian and C Y Liu Support System of Supportand Surrounding Rock for High Productivity and High Effi-ciency Working Face China Mining Industry Press XuzhouChina 1997 in Chinese
[6] S J Chen Y Wang Y Z Wu Z Wang and W J ZhangldquoCoal resources and development potential in northwestChinardquo Northwestern Geology vol 4 pp 40ndash56 2006 inChinese
[7] X M Sun and M C He ldquoNumerical simulation research oncoupling support theory of roadway within soft rock atdepthrdquo Journal of China University of Mining and Technologyvol 34 no 2 pp 166ndash169 2005 in Chinese
[8] S X Wei J H Song and H W Jing ldquoNumerical analysis ofstress in the surrounding rock of the dynamic pressure tunnelwith inclined seamsrdquo Metal Mine vol 41 no 3 pp 37ndash412012 in Chinese
[9] H Wang B Xia Y Lu T Gong and R Zhang ldquoStudy on thepropagation laws of hydrofractures meeting a faulted struc-ture in the coal seamrdquo Energies vol 10 no 5 pp 654ndash6722017
[10] J Xie J Xu and FWang ldquoMining-induced stress distributionof the working face in a kilometer-deep coal mine-a case studyin Tangshan coal minerdquo Journal of Geophysics and Engi-neering vol 15 no 5 pp 2060ndash2070 2018
[11] S Zhang X Wang G Fan D Zhang and C Jianbin ldquoPillarsize optimization design of isolated island panel gob-sideentry driving in deep inclined coal seam-case study ofPingmei No 6 coal seamrdquo Journal of Geophysics and Engi-neering vol 15 no 3 pp 816ndash828 2018
[12] Y Yuan S Tu F Wang X Zhang and B Li ldquoHydraulicsupport instability mechanism and its control in a fully-mechanized steep coal seam working face with large miningheightrdquo Journal of the Southern African Institute of Miningand Metallurgy vol 115 no 5 pp 441ndash447 2015
[13] J Sun L Wang and G Zhao ldquoFailure characteristics andconfined permeability of an inclined coal seam floor in fluid-solid couplingrdquo Advances in Civil Engineering vol 2018Article ID 2356390 12 pages 2018
[14] S Gu B Jiang G Wang H Dai and M Zhang ldquoOccurrencemechanism of roof-fall accidents in large-section coal seamroadways and related support design for Bayangaole coalmine Chinardquo Advances in Civil Engineering vol 2018 ArticleID 6831731 17 pages 2018
[15] H Xie M Gao R Zhang G Peng W Wang and A LildquoStudy on the mechanical properties andmechanical response
Advances in Civil Engineering 13
of coal mining at 1000m or deeperrdquo RockMechanics and RockEngineering vol 52 no 5 pp 1475ndash1490 2019
[16] Y Fang C Xu G Cui and B Kenneally ldquoScale model test ofhighway tunnel construction underlying mined-out thin coalseamrdquo Tunnelling and Underground Space Technology vol 56pp 105ndash116 2016
[17] M C He ldquoPhysical modeling of an underground roadwayexcavation in geologically 45deg inclined rock using infraredthermographyrdquo Engineering Geology vol 121 no 3-4pp 165ndash176 2011
[18] W Gong Y Peng M He and J Wang ldquoermal image andspectral characterization of roadway failure process in geo-logically 45deg inclined rocksrdquo Tunnelling and UndergroundSpace Technology vol 49 pp 156ndash173 2015
[19] H Yang S Cao Y Li C Sun and P Guo ldquoSoft roof failuremechanism and supporting method for gob-side entryretainingrdquo Minerals vol 5 no 4 pp 707ndash722 2015
[20] L Q Ma Y Zhang D S Zhang X Q Cao Q Q Li andY B Zhang ldquoSupport stability mechanism in a coal face withlarge angles in both strike and diprdquo Journal of the SouthernAfrican Institute of Mining and Metallurgy vol 115 no 7pp 599ndash606 2015
[21] M Jawed and R K Sinha ldquoDesign of rhombus coal pillars andsupport for roadway stability and mechanizing loading of facecoal using SDLs in a steeply inclined thin coal seammdashatechnical feasibility studyrdquo Arabian Journal of Geosciencesvol 11 no 15 pp 415ndash429 2018
[22] Y Yin J Zou Y Zhang Y Qiu and K Fang ldquoExperimentalstudy of the movement of backfilling gangues for goaf insteeply inclined coal seamsrdquo Arabian Journal of Geosciencesvol 11 no 12 pp 318ndash326 2018
[23] L Q Zhu and Y Zhang ldquoAnalysis of spontaneous com-bustion ldquothree zonesrdquo in 3237 working face of zhaogezhuangminerdquo Applied Mechanics and Materials vol 71ndash78pp 1978ndash1982 2011
[24] S Q He D Z Song Z L Li et al ldquoPrecursor of spatio-temporal evolution law of MS and AE activities for rock burstwarning in steeply inclined and extremely thick coal seamsunder caving mining conditionsrdquo Rock Mechanics and RockEngineering no 2 pp 1ndash21 2019
[25] H S Tu S H Tu Y Yuan F T Wang and Q S Bai ldquoPresentsituation of fully mechanized mining technology for steeplyinclined coal seams in Chinardquo Arabian Journal of Geosciencesvol 8 no 7 pp 1978ndash1982 2015
[26] W Lv Y Wu L Ming and J Yin ldquoMigration law of the roofof a composited backfilling longwall face in a steeply dippingcoal seamrdquo Minerals vol 9 no 3 pp 188ndash203 2019
[27] Z Bei S G Cao L G Wang and Y L Lu ldquoDeformationfailure mechanism and support measurements in roadway ofsteeply inclined coal seamrdquo Journal of Mining amp Safety En-gineering vol 28 no 2 pp 214ndash219 2011
[28] M Z Gao and H Q Jing ldquoMechanical analysis of asymmetricfloor heave of roadwayrdquo Journal of Anhui University of Scienceand Technology vol 32 no 4 pp 38ndash43 2012 in Chinese
[29] J G Liu A Y Cao Z M Yu G C Jing and H Y Liu ldquoStudyon stress characteristics of roadwayrsquos sides in deep and in-clined seamrdquo China Coal vol 42 no 8 pp 30ndash34 2016 inChinese
[30] X H Qi ldquoStudy on deformation characters and supportparameters of large angle seam roadway rock aroundrdquo Dis-sertation Xirsquoan University of Science and Technology XirsquoanChina 2015 in chinese
14 Advances in Civil Engineering
0 3 6 9 12 15 18 21 240
5
10
15
20
25
30
35
40
High sideLow side
Stre
ss (M
Pa)
q (MPa)
(a)
High sideLow side
q (MPa)0 3 6 9 12 15 18 21 24
0
5
10
15
20
25
30
35
40
45
Stre
ss (M
Pa)
(b)
High sideLow side
q (MPa)0 3 6 9 12 15 18 21 24
0
5
10
15
20
25
30
35
40
Stre
ss (M
Pa)
(c)
High sideLow side
q (MPa)0 3 6 9 12 15 18 21 24
0
5
10
15
20
25
30
35
40
Stre
ss (M
Pa)
(d)
Figure 6 Comparative analysis curves of peak stress and ground stress of the two sides of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
15 18 21 24 27 300
3
6
9
12
Dip angle (deg)
High sideLow side
Dist
ance
(m)
(a)
Dip angle (deg)
High sideLow side
Dist
ance
(m)
15 18 21 24 27 303
6
9
12
15
(b)
Figure 7 Curve of the change in stress concentration peak with the side distance of the two sides of the roadway with inclination angle (a)10MPa (b) 20MPa
Advances in Civil Engineering 5
43 Horizontal Displacement Characteristics of the RoadwayFigures 9 and 10 depict the horizontal stress nephogram ofthe roadway and the displacement analysis diagram of thetwo walls of the roadway with different simulated groundstresses q and different inclination angles respectivelyFigures 9 and 10 and Table 3 reveal that the displacementdifference between the two walls of the roadway is obviousand increases with the increase in group stress e groupstress is 10ndash15MPa and the inclination angle is 18deg and theroadwayrsquos high side is 15ndash77mm larger than the low sideHowever the difference decreases with the increase in in-clination angle When the inclination angle is 18ndash27deg and thegroup stress is 10MPa the roadwayrsquos high side is 15ndash10mm
larger than the low side e main reason is that the dif-ference in height between the two walls leads to unevenstress distribution
5 Validation of the Simulation Test
51 Test Plan To verify the asymmetric stress distributioncharacteristics of the surrounding rock of the right-angledtrapezoidal roadway in the inclined seam further the lab-oratory model test adopted the principle of geometricsimilarity and strength equality and established four types ofright-angled trapezoidal roadway test models with differentinclined seam angles namely 18deg 21deg 24deg and 27deg
Table 2 Distance from peak stress concentration to both sides of roadway (mm)
Dip angleGround stress 10MPa Ground stress 20MPa
Low side High side Low side High side18deg 642 514 1203 106721deg 605 405 1185 98524deg 54 29 1118 83827deg 501 201 1055 665
70522E + 0570000E + 0560000E + 0550000E + 0540000E + 0530000E + 0520000E + 0510000E + 0500000E + 00ndash10000E + 05ndash20000E + 05ndash30000E + 05ndash40000E + 05ndash50000E + 05ndash60000E + 05ndash70000E + 05ndash80000E + 05ndash90000E + 05ndash90594E + 05
Stress (Pa)
(a)
94567E + 0580000E + 0560000E + 0540000E + 0520000E + 0500000E + 00ndash20000E + 05ndash40000E + 05ndash60000E + 05ndash80000E + 05ndash10000E + 06ndash11309E + 06
Stress (Pa)
(b)
ndash10000E + 05ndash20000E + 05ndash30000E + 05ndash40000E + 05ndash50000E + 05ndash60000E + 05ndash70000E + 05ndash76621E + 05
39580E + 0530000E + 0520000E + 0510000E + 0500000E + 00
Stress (Pa)
(c)
ndash10000E + 05ndash20000E + 05ndash30000E + 05ndash40000E + 05ndash50000E + 05ndash60000E + 05ndash64765E + 05
39675E + 0530000E + 0520000E + 0510000E + 0500000E + 00
Stress (Pa)
(d)
Figure 8 Horizontal stress distribution characteristics of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
6 Advances in Civil Engineering
Displacement (m)
ndash50000E ndash 04ndash10000E ndash 03ndash15000E ndash 03ndash20000E ndash 03ndash22092E ndash 03
35007E ndash 03
30000E ndash 0335000E ndash 03
25000E ndash 0320000E ndash 0315000E ndash 0310000E ndash 0350000E ndash 0400000E + 00
(a)
Displacement (m)
ndash25000E ndash 04ndash50000E ndash 04ndash75000E ndash 04ndash10000E ndash 03ndash12500E ndash 03ndash12767E ndash 03
20000E ndash 0321873E ndash 03
15000E ndash 0317500E ndash 03
12500E ndash 0310000E ndash 0375000E ndash 0450000E ndash 0425000E ndash 0400000E + 00
(b)
Displacement (m)
ndash25000E ndash 04ndash50000E ndash 04ndash75000E ndash 04ndash10000E ndash 03ndash12500E ndash 03ndash15000E ndash 03ndash17500E ndash 03ndash18776E ndash 03
20000E ndash 03
15000E ndash 0317500E ndash 03
12500E ndash 0310000E ndash 03
26609E ndash 0325000E ndash 0322500E ndash 03
75000E ndash 0450000E ndash 0425000E ndash 0400000E + 00
(c)
Displacement (m)
ndash25000E ndash 04ndash50000E ndash 04ndash75000E ndash 04ndash10000E ndash 03ndash10040E ndash 03
15000E ndash 0316911E ndash 03
12500E ndash 0310000E ndash 0375000E ndash 0450000E ndash 0425000E ndash 0400000E + 00
(d)
Figure 9 Horizontal stress distribution characteristics of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
0 3 6 9 12 15 18 21 240
30
60
90
120
150
180
210
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)
(a)
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)0 3 6 9 12 15 18 21 24
0
30
60
90
120
150
180
(b)
Figure 10 Continued
Advances in Civil Engineering 7
(Figure 11)e geometric similarity ratio is 1 30 the modelsize is 72 cmtimes 72 cmtimes 10 cm and the lithology parametersare selected from the engineering background of the Shi-tanjing No 2 mining area which is the same as that for thenumerical simulation Different proportions of cementmortar were used to simulate the characteristics
e measurement points are arranged at the roadwaywalls roof and floor as well as the corners A verticaluniform load is applied to the model in a stepwise manneruntil the specimen is completely destroyede strain valuesof each measurement point under different loads arerecorded in real time during the loading process
52 Analysis of Test Results
521 Stress Distribution Law of the Roof Surrounding theRock Figure 12 displays a simulated ground stress-straincurve of the roof surrounding the rock of the trapezoidalroadway with different dip angles e stress of the roofsurrounding the rock of the roadway presents obviousasymmetric characteristics and the size distribution of themiddle measuring point of the roof (Intermediate)gt the lowside measuring point of the roof (R- low side)gt the high sidemeasuring point of the roof (R- high side) from Figure 12 Inaddition the maximum strain on the low side of the sur-rounding rock is significantly larger than that on the highside e greater the dip angle the more obvious the dif-ference in stress distribution between the high and low sides
of the surrounding rock of the roadway When the incli-nation angle is in the range of 18degndash27deg the maximum strainon the right wall of the roof (R- low side) is 13ndash21 timeslarger than that on the left wall of the roof (R- high side)
522 Stress Distribution Law of the Surrounding Rocks of theTwo Walls of the Roadway Figure 13 describes the simu-lated ground stress-strain curve of the surrounding rock ofthe right-angled trapezoidal roadway with different dipangles It can be concluded that the stress concentrations onthe two walls of the roadway are clearly different and theyincrease with increasing inclination and ground stress einclination angle is 18degndash27deg and the maximum value of theright wall (low side) stress concentration is 12ndash17 times thatof the left wall (high side)
523 Stress Distribution Law of the Two Surrounding RocksFigure 14 is a simulated ground stress-strain curve of thesurrounding rock at the corners of a right-angled trapezoidalroadway with different dip angles Figure 14 reveals that thestress distribution of each point at the four corners of theroadway is different From large to small the order is lowside shoulder angle (LSSA) high side shoulder angle(HSSA) low side bottom angle (LSBA) and high sidebottom angle (HSBA) When the dip angle is 18deg LSSArsquosstrain is 2ndash4 times of other sharp angles it changes with thechange in inclination
524 Analysis of Stress Distribution in the Surrounding Rockof the Roadway Floor Figure 15 is a simulated groundstress-strain curve of the surrounding rock of a rectangulartrapezoidal roadway with different dip angles It can be seenfrom Figure 15 that under the action of the upper roof andthe two sets of asymmetric stress the stress distribution ofthe floor of the roadway also exhibits obvious asymmetry
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)0 3 6 9 12 15 18 21 24
0
20
40
60
80
100
120
(c)
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)0 3 6 9 12 15 18 21 24
0
10
20
30
40
50
60
(d)
Figure 10 Analysis curves of the horizontal displacements of the two sides of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Table 3 Horizontal displacement of two sides of roadway (mm)
Dip angleGround stress 10MPa Ground stress 20MPaLow side High side Low side High side
18deg 2254 3747 11551 1925321deg 2389 3131 11464 1590024deg 1493 2301 7288 1068927deg 71 17 2141 5881
8 Advances in Civil Engineering
Data analysis
Computer
Strain gauge
Monitoring point
Loading
07m 01m
072
m
015m
01m
R-high side R-low sideIntermediate
LSSAHSSA
LSBAHSBA
High sideLow side
F-high side F-low side
Figure 11 Test models of the right-angled trapezoidal roadway
0
1
2
3
4
5
6
7
8
0 25 50 75 100 125 150 175Strain (10ndash6)
Stre
ss (M
Pa)
R-high sideIntermediateR-low side
(a)
Strain (10ndash6)
Stre
ss (M
Pa)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
7
0 30 60 90 120 150 180 210
(b)
Stre
ss (M
Pa)
Strain (10ndash6)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
0 40 80 120 160 200 240 280
(c)
Stre
ss (M
Pa)
Strain (10ndash6)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
0 50 100 150 200 250 300 350
(d)
Figure 12 Stress-strain curves of the roof surrounding the rock (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Advances in Civil Engineering 9
0
1
2
3
4
5
6
7
8
0 600 1200 1800 2400 3000
High sideLow side
Stre
ss (M
Pa)
Strain (10ndash6)
(a)
High sideLow side
0
1
2
3
4
5
6
7
0 300 600 900 1200 1500 1800
Stre
ss (M
Pa)
Strain (10ndash6)
(b)
0
1
2
3
4
5
6
0 800 1600 2400 3200
Stre
ss (M
Pa)
High sideLow side
Strain (10ndash6)
(c)
Stre
ss (M
Pa)
0
1
2
3
4
5
0 500 1000 1500 2000 2500
High sideLow side
Strain (10ndash6)
(d)
Figure 13 Stress-strain curve of the surrounding rock of the two sides of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
0
1
2
3
4
5
6
7
8
0 150 300 450 600 750 900
Stre
ss (M
Pa)
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(a)
Stre
ss (M
Pa)
0
1
2
3
4
5
6
7
0 200 400 600 800 1000 1200 1400
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(b)
Figure 14 Continued
10 Advances in Civil Engineering
Stre
ss (M
Pa)
0
1
2
3
4
5
6
0 200 400 600 800 1000 1200
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(c)
Stre
ss (M
Pa)
0
1
2
3
4
5
0 200 400 600 800 1000 1200 1400
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(d)
Figure 14 Stress-strain curve of the surrounding rock at the corner of the roadway (a) 18deg (b) 21deg (c) 27deg (d) 27deg
F-high sideF-low side
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
Stre
ss (M
Pa)
Strain (10ndash6)
(a)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
6
7
0 20 40 60 80 100 120 140 160Strain (10ndash6)
(b)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
6
0 30 60 90 120 150 180Strain (10ndash6)
(c)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
0 25 50 75 100 125Strain (10ndash6)
(d)
Figure 15 Stress-strain curve of roadway floor (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Advances in Civil Engineering 11
and the stress on the right wall of the floor (F-low side) isgreater than that on the left wall of the floor (F-high side)
From the laboratory model test results it can be seen thatthe stress distribution law of the right-angled trapezoidalroadway in a gently inclined seam is similar to the numericalsimulation and the stress distribution of the surroundingrock in the roof the two walls the floor and the corner of theroadway shows clear asymmetric characteristics howeverthere are some differences in the numerical valuese mainreason is that the proportion of similar materials size of themodel loading mode and so on have an impact on the testresults
6 Comparison and Analysis ofSimulation Results
It can be seen from the simulation results that the asym-metric distribution law of the surrounding rock in inclinedright angle trapezoidal roadway is basically the same as thatof large dip angle and steep inclined coal seam roadway butthe degree of stress asymmetry in the inclined coal seam ismuch lower than that of large dip angle coal seam enumerical simulation results of the asymmetric deformationand failure characteristics of the inclined trapezoidal
roadway in the inclined coal seam are consistent with thelaboratory model test (Figure 16) and the site failuremorphology of the Shitanjing No 2 mine (Figure 17) inwhich the deformation and failure law exhibits an asym-metrical feature Further the two walls of the roadway areseverely bulging and the low side is larger than the high side
7 Conclusion
Based on the theory of asymmetric stress distribution in thesurrounding rock of right-angled trapezoidal roadway in aninclined coal seam and considering the Shijiajing No 2mining area as the engineering background this paperfurther analyzes the asymmetric distribution characteristicsof the surrounding rock by using the FLAC3D finite dif-ference method rough verifications with a simulationtest the following conclusions were drawn
(1) e stress distribution of the surrounding rock of theright-angled trapezoidal roadway in the inclined coalseam shows clear asymmetryemain performanceis that the peak value of stress concentration in thelow side is greater than that in the high side and thedistance between the high side and the side wall ofthe roadway is greater than that in the low side With
(a) (b)
Figure 16 Deformation and failure of roadway in laboratory model test (a) 24deg (b) 27deg
(a) (b)
Figure 17 Deformation and failure of roadway in Shitanjing No 2 mine (a) 24deg (b) 27deg
12 Advances in Civil Engineering
the increase in the inclination angle and groundstress the difference between the peak value of stressconcentration and the distance from the side wall ofthe roadway is more obvious When the inclinationangle is 18degndash27deg the peak value of stress concen-tration of the low side is 107ndash133 times that of thehigh side and the distance from the high side to theside wall of the roadway is 126ndash379m larger thanthat of the low side Second two sharp corners thatare symmetric with the same inclination angle of thecoal seam show obvious compressive stress regionswhile the opposite two sharp corners show obvioustensile stress regions e maximum values ofcompressive and tensile stresses appear on the roof ofthe roadway
(2) Under the action of asymmetric stress the defor-mation and failure of the roadway surrounding therock also presents asymmetric characteristics etwo walls of the roadway exhibit extrusion dislo-cation and serious deformation and damage how-ever the deformation damage of the low side isobviously larger than that at the high side e mainreason is that the difference in height between thetwo walls of the roadway leads to the uneven dis-tribution of stress
(3) e results of numerical simulation are basicallyconsistent with laboratory model test and field en-gineering However there are some differences in thedata obtained and the main reason is that the two areaffected by the selection of the simulation parame-ters ratio of similar materials size of the model andloading method
Data Availability
e data used to support the findings of this study are in-cluded within the article
Conflicts of Interest
e authors declare that they have no conflicts of interestregarding the publication of this paper
Acknowledgments
is study was financially supported by the National NaturalScience Foundation of China (51174159 and 59974019) theChina Postdoctoral Science Foundation (2015M572580)and the Scientific Research Plan Projects of EducationDepartment of Shanxi Province of China (15JK1471)
Supplementary Materials
eoretical analysis process of roof stress distribution ininclined coal seam roadway (Supplementary Materials)
References
[1] H C Li ldquoStudy on deformation and failure characteristicsand stability control of large dip angle thick compound roofroadwayrdquo Dissertation Taiyuan University of TechnologyTaiyuan China 2014
[2] e National Development and Reform Commission PeoplersquosRepublic of China Energy Development 11th Five-Year PlanBeijing China 2007 in Chinese
[3] K Yu L Zhou Q Cao and Z Li ldquoEvolutionary game re-search on symmetry of workersrsquo behavior in coal mine en-terprisesrdquo Symmetry vol 11 no 2 pp 156ndash168 2019
[4] L Si Z Wang R Xu C Tan X Liu and J Xu ldquoImageenhancement for surveillance video of coal mining face basedon single-scale retinex algorithm combined with bilateralfilteringrdquo Symmetry vol 9 no 6 pp 93ndash108 2017
[5] F L He M G Qian and C Y Liu Support System of Supportand Surrounding Rock for High Productivity and High Effi-ciency Working Face China Mining Industry Press XuzhouChina 1997 in Chinese
[6] S J Chen Y Wang Y Z Wu Z Wang and W J ZhangldquoCoal resources and development potential in northwestChinardquo Northwestern Geology vol 4 pp 40ndash56 2006 inChinese
[7] X M Sun and M C He ldquoNumerical simulation research oncoupling support theory of roadway within soft rock atdepthrdquo Journal of China University of Mining and Technologyvol 34 no 2 pp 166ndash169 2005 in Chinese
[8] S X Wei J H Song and H W Jing ldquoNumerical analysis ofstress in the surrounding rock of the dynamic pressure tunnelwith inclined seamsrdquo Metal Mine vol 41 no 3 pp 37ndash412012 in Chinese
[9] H Wang B Xia Y Lu T Gong and R Zhang ldquoStudy on thepropagation laws of hydrofractures meeting a faulted struc-ture in the coal seamrdquo Energies vol 10 no 5 pp 654ndash6722017
[10] J Xie J Xu and FWang ldquoMining-induced stress distributionof the working face in a kilometer-deep coal mine-a case studyin Tangshan coal minerdquo Journal of Geophysics and Engi-neering vol 15 no 5 pp 2060ndash2070 2018
[11] S Zhang X Wang G Fan D Zhang and C Jianbin ldquoPillarsize optimization design of isolated island panel gob-sideentry driving in deep inclined coal seam-case study ofPingmei No 6 coal seamrdquo Journal of Geophysics and Engi-neering vol 15 no 3 pp 816ndash828 2018
[12] Y Yuan S Tu F Wang X Zhang and B Li ldquoHydraulicsupport instability mechanism and its control in a fully-mechanized steep coal seam working face with large miningheightrdquo Journal of the Southern African Institute of Miningand Metallurgy vol 115 no 5 pp 441ndash447 2015
[13] J Sun L Wang and G Zhao ldquoFailure characteristics andconfined permeability of an inclined coal seam floor in fluid-solid couplingrdquo Advances in Civil Engineering vol 2018Article ID 2356390 12 pages 2018
[14] S Gu B Jiang G Wang H Dai and M Zhang ldquoOccurrencemechanism of roof-fall accidents in large-section coal seamroadways and related support design for Bayangaole coalmine Chinardquo Advances in Civil Engineering vol 2018 ArticleID 6831731 17 pages 2018
[15] H Xie M Gao R Zhang G Peng W Wang and A LildquoStudy on the mechanical properties andmechanical response
Advances in Civil Engineering 13
of coal mining at 1000m or deeperrdquo RockMechanics and RockEngineering vol 52 no 5 pp 1475ndash1490 2019
[16] Y Fang C Xu G Cui and B Kenneally ldquoScale model test ofhighway tunnel construction underlying mined-out thin coalseamrdquo Tunnelling and Underground Space Technology vol 56pp 105ndash116 2016
[17] M C He ldquoPhysical modeling of an underground roadwayexcavation in geologically 45deg inclined rock using infraredthermographyrdquo Engineering Geology vol 121 no 3-4pp 165ndash176 2011
[18] W Gong Y Peng M He and J Wang ldquoermal image andspectral characterization of roadway failure process in geo-logically 45deg inclined rocksrdquo Tunnelling and UndergroundSpace Technology vol 49 pp 156ndash173 2015
[19] H Yang S Cao Y Li C Sun and P Guo ldquoSoft roof failuremechanism and supporting method for gob-side entryretainingrdquo Minerals vol 5 no 4 pp 707ndash722 2015
[20] L Q Ma Y Zhang D S Zhang X Q Cao Q Q Li andY B Zhang ldquoSupport stability mechanism in a coal face withlarge angles in both strike and diprdquo Journal of the SouthernAfrican Institute of Mining and Metallurgy vol 115 no 7pp 599ndash606 2015
[21] M Jawed and R K Sinha ldquoDesign of rhombus coal pillars andsupport for roadway stability and mechanizing loading of facecoal using SDLs in a steeply inclined thin coal seammdashatechnical feasibility studyrdquo Arabian Journal of Geosciencesvol 11 no 15 pp 415ndash429 2018
[22] Y Yin J Zou Y Zhang Y Qiu and K Fang ldquoExperimentalstudy of the movement of backfilling gangues for goaf insteeply inclined coal seamsrdquo Arabian Journal of Geosciencesvol 11 no 12 pp 318ndash326 2018
[23] L Q Zhu and Y Zhang ldquoAnalysis of spontaneous com-bustion ldquothree zonesrdquo in 3237 working face of zhaogezhuangminerdquo Applied Mechanics and Materials vol 71ndash78pp 1978ndash1982 2011
[24] S Q He D Z Song Z L Li et al ldquoPrecursor of spatio-temporal evolution law of MS and AE activities for rock burstwarning in steeply inclined and extremely thick coal seamsunder caving mining conditionsrdquo Rock Mechanics and RockEngineering no 2 pp 1ndash21 2019
[25] H S Tu S H Tu Y Yuan F T Wang and Q S Bai ldquoPresentsituation of fully mechanized mining technology for steeplyinclined coal seams in Chinardquo Arabian Journal of Geosciencesvol 8 no 7 pp 1978ndash1982 2015
[26] W Lv Y Wu L Ming and J Yin ldquoMigration law of the roofof a composited backfilling longwall face in a steeply dippingcoal seamrdquo Minerals vol 9 no 3 pp 188ndash203 2019
[27] Z Bei S G Cao L G Wang and Y L Lu ldquoDeformationfailure mechanism and support measurements in roadway ofsteeply inclined coal seamrdquo Journal of Mining amp Safety En-gineering vol 28 no 2 pp 214ndash219 2011
[28] M Z Gao and H Q Jing ldquoMechanical analysis of asymmetricfloor heave of roadwayrdquo Journal of Anhui University of Scienceand Technology vol 32 no 4 pp 38ndash43 2012 in Chinese
[29] J G Liu A Y Cao Z M Yu G C Jing and H Y Liu ldquoStudyon stress characteristics of roadwayrsquos sides in deep and in-clined seamrdquo China Coal vol 42 no 8 pp 30ndash34 2016 inChinese
[30] X H Qi ldquoStudy on deformation characters and supportparameters of large angle seam roadway rock aroundrdquo Dis-sertation Xirsquoan University of Science and Technology XirsquoanChina 2015 in chinese
14 Advances in Civil Engineering
43 Horizontal Displacement Characteristics of the RoadwayFigures 9 and 10 depict the horizontal stress nephogram ofthe roadway and the displacement analysis diagram of thetwo walls of the roadway with different simulated groundstresses q and different inclination angles respectivelyFigures 9 and 10 and Table 3 reveal that the displacementdifference between the two walls of the roadway is obviousand increases with the increase in group stress e groupstress is 10ndash15MPa and the inclination angle is 18deg and theroadwayrsquos high side is 15ndash77mm larger than the low sideHowever the difference decreases with the increase in in-clination angle When the inclination angle is 18ndash27deg and thegroup stress is 10MPa the roadwayrsquos high side is 15ndash10mm
larger than the low side e main reason is that the dif-ference in height between the two walls leads to unevenstress distribution
5 Validation of the Simulation Test
51 Test Plan To verify the asymmetric stress distributioncharacteristics of the surrounding rock of the right-angledtrapezoidal roadway in the inclined seam further the lab-oratory model test adopted the principle of geometricsimilarity and strength equality and established four types ofright-angled trapezoidal roadway test models with differentinclined seam angles namely 18deg 21deg 24deg and 27deg
Table 2 Distance from peak stress concentration to both sides of roadway (mm)
Dip angleGround stress 10MPa Ground stress 20MPa
Low side High side Low side High side18deg 642 514 1203 106721deg 605 405 1185 98524deg 54 29 1118 83827deg 501 201 1055 665
70522E + 0570000E + 0560000E + 0550000E + 0540000E + 0530000E + 0520000E + 0510000E + 0500000E + 00ndash10000E + 05ndash20000E + 05ndash30000E + 05ndash40000E + 05ndash50000E + 05ndash60000E + 05ndash70000E + 05ndash80000E + 05ndash90000E + 05ndash90594E + 05
Stress (Pa)
(a)
94567E + 0580000E + 0560000E + 0540000E + 0520000E + 0500000E + 00ndash20000E + 05ndash40000E + 05ndash60000E + 05ndash80000E + 05ndash10000E + 06ndash11309E + 06
Stress (Pa)
(b)
ndash10000E + 05ndash20000E + 05ndash30000E + 05ndash40000E + 05ndash50000E + 05ndash60000E + 05ndash70000E + 05ndash76621E + 05
39580E + 0530000E + 0520000E + 0510000E + 0500000E + 00
Stress (Pa)
(c)
ndash10000E + 05ndash20000E + 05ndash30000E + 05ndash40000E + 05ndash50000E + 05ndash60000E + 05ndash64765E + 05
39675E + 0530000E + 0520000E + 0510000E + 0500000E + 00
Stress (Pa)
(d)
Figure 8 Horizontal stress distribution characteristics of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
6 Advances in Civil Engineering
Displacement (m)
ndash50000E ndash 04ndash10000E ndash 03ndash15000E ndash 03ndash20000E ndash 03ndash22092E ndash 03
35007E ndash 03
30000E ndash 0335000E ndash 03
25000E ndash 0320000E ndash 0315000E ndash 0310000E ndash 0350000E ndash 0400000E + 00
(a)
Displacement (m)
ndash25000E ndash 04ndash50000E ndash 04ndash75000E ndash 04ndash10000E ndash 03ndash12500E ndash 03ndash12767E ndash 03
20000E ndash 0321873E ndash 03
15000E ndash 0317500E ndash 03
12500E ndash 0310000E ndash 0375000E ndash 0450000E ndash 0425000E ndash 0400000E + 00
(b)
Displacement (m)
ndash25000E ndash 04ndash50000E ndash 04ndash75000E ndash 04ndash10000E ndash 03ndash12500E ndash 03ndash15000E ndash 03ndash17500E ndash 03ndash18776E ndash 03
20000E ndash 03
15000E ndash 0317500E ndash 03
12500E ndash 0310000E ndash 03
26609E ndash 0325000E ndash 0322500E ndash 03
75000E ndash 0450000E ndash 0425000E ndash 0400000E + 00
(c)
Displacement (m)
ndash25000E ndash 04ndash50000E ndash 04ndash75000E ndash 04ndash10000E ndash 03ndash10040E ndash 03
15000E ndash 0316911E ndash 03
12500E ndash 0310000E ndash 0375000E ndash 0450000E ndash 0425000E ndash 0400000E + 00
(d)
Figure 9 Horizontal stress distribution characteristics of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
0 3 6 9 12 15 18 21 240
30
60
90
120
150
180
210
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)
(a)
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)0 3 6 9 12 15 18 21 24
0
30
60
90
120
150
180
(b)
Figure 10 Continued
Advances in Civil Engineering 7
(Figure 11)e geometric similarity ratio is 1 30 the modelsize is 72 cmtimes 72 cmtimes 10 cm and the lithology parametersare selected from the engineering background of the Shi-tanjing No 2 mining area which is the same as that for thenumerical simulation Different proportions of cementmortar were used to simulate the characteristics
e measurement points are arranged at the roadwaywalls roof and floor as well as the corners A verticaluniform load is applied to the model in a stepwise manneruntil the specimen is completely destroyede strain valuesof each measurement point under different loads arerecorded in real time during the loading process
52 Analysis of Test Results
521 Stress Distribution Law of the Roof Surrounding theRock Figure 12 displays a simulated ground stress-straincurve of the roof surrounding the rock of the trapezoidalroadway with different dip angles e stress of the roofsurrounding the rock of the roadway presents obviousasymmetric characteristics and the size distribution of themiddle measuring point of the roof (Intermediate)gt the lowside measuring point of the roof (R- low side)gt the high sidemeasuring point of the roof (R- high side) from Figure 12 Inaddition the maximum strain on the low side of the sur-rounding rock is significantly larger than that on the highside e greater the dip angle the more obvious the dif-ference in stress distribution between the high and low sides
of the surrounding rock of the roadway When the incli-nation angle is in the range of 18degndash27deg the maximum strainon the right wall of the roof (R- low side) is 13ndash21 timeslarger than that on the left wall of the roof (R- high side)
522 Stress Distribution Law of the Surrounding Rocks of theTwo Walls of the Roadway Figure 13 describes the simu-lated ground stress-strain curve of the surrounding rock ofthe right-angled trapezoidal roadway with different dipangles It can be concluded that the stress concentrations onthe two walls of the roadway are clearly different and theyincrease with increasing inclination and ground stress einclination angle is 18degndash27deg and the maximum value of theright wall (low side) stress concentration is 12ndash17 times thatof the left wall (high side)
523 Stress Distribution Law of the Two Surrounding RocksFigure 14 is a simulated ground stress-strain curve of thesurrounding rock at the corners of a right-angled trapezoidalroadway with different dip angles Figure 14 reveals that thestress distribution of each point at the four corners of theroadway is different From large to small the order is lowside shoulder angle (LSSA) high side shoulder angle(HSSA) low side bottom angle (LSBA) and high sidebottom angle (HSBA) When the dip angle is 18deg LSSArsquosstrain is 2ndash4 times of other sharp angles it changes with thechange in inclination
524 Analysis of Stress Distribution in the Surrounding Rockof the Roadway Floor Figure 15 is a simulated groundstress-strain curve of the surrounding rock of a rectangulartrapezoidal roadway with different dip angles It can be seenfrom Figure 15 that under the action of the upper roof andthe two sets of asymmetric stress the stress distribution ofthe floor of the roadway also exhibits obvious asymmetry
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)0 3 6 9 12 15 18 21 24
0
20
40
60
80
100
120
(c)
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)0 3 6 9 12 15 18 21 24
0
10
20
30
40
50
60
(d)
Figure 10 Analysis curves of the horizontal displacements of the two sides of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Table 3 Horizontal displacement of two sides of roadway (mm)
Dip angleGround stress 10MPa Ground stress 20MPaLow side High side Low side High side
18deg 2254 3747 11551 1925321deg 2389 3131 11464 1590024deg 1493 2301 7288 1068927deg 71 17 2141 5881
8 Advances in Civil Engineering
Data analysis
Computer
Strain gauge
Monitoring point
Loading
07m 01m
072
m
015m
01m
R-high side R-low sideIntermediate
LSSAHSSA
LSBAHSBA
High sideLow side
F-high side F-low side
Figure 11 Test models of the right-angled trapezoidal roadway
0
1
2
3
4
5
6
7
8
0 25 50 75 100 125 150 175Strain (10ndash6)
Stre
ss (M
Pa)
R-high sideIntermediateR-low side
(a)
Strain (10ndash6)
Stre
ss (M
Pa)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
7
0 30 60 90 120 150 180 210
(b)
Stre
ss (M
Pa)
Strain (10ndash6)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
0 40 80 120 160 200 240 280
(c)
Stre
ss (M
Pa)
Strain (10ndash6)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
0 50 100 150 200 250 300 350
(d)
Figure 12 Stress-strain curves of the roof surrounding the rock (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Advances in Civil Engineering 9
0
1
2
3
4
5
6
7
8
0 600 1200 1800 2400 3000
High sideLow side
Stre
ss (M
Pa)
Strain (10ndash6)
(a)
High sideLow side
0
1
2
3
4
5
6
7
0 300 600 900 1200 1500 1800
Stre
ss (M
Pa)
Strain (10ndash6)
(b)
0
1
2
3
4
5
6
0 800 1600 2400 3200
Stre
ss (M
Pa)
High sideLow side
Strain (10ndash6)
(c)
Stre
ss (M
Pa)
0
1
2
3
4
5
0 500 1000 1500 2000 2500
High sideLow side
Strain (10ndash6)
(d)
Figure 13 Stress-strain curve of the surrounding rock of the two sides of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
0
1
2
3
4
5
6
7
8
0 150 300 450 600 750 900
Stre
ss (M
Pa)
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(a)
Stre
ss (M
Pa)
0
1
2
3
4
5
6
7
0 200 400 600 800 1000 1200 1400
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(b)
Figure 14 Continued
10 Advances in Civil Engineering
Stre
ss (M
Pa)
0
1
2
3
4
5
6
0 200 400 600 800 1000 1200
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(c)
Stre
ss (M
Pa)
0
1
2
3
4
5
0 200 400 600 800 1000 1200 1400
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(d)
Figure 14 Stress-strain curve of the surrounding rock at the corner of the roadway (a) 18deg (b) 21deg (c) 27deg (d) 27deg
F-high sideF-low side
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
Stre
ss (M
Pa)
Strain (10ndash6)
(a)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
6
7
0 20 40 60 80 100 120 140 160Strain (10ndash6)
(b)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
6
0 30 60 90 120 150 180Strain (10ndash6)
(c)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
0 25 50 75 100 125Strain (10ndash6)
(d)
Figure 15 Stress-strain curve of roadway floor (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Advances in Civil Engineering 11
and the stress on the right wall of the floor (F-low side) isgreater than that on the left wall of the floor (F-high side)
From the laboratory model test results it can be seen thatthe stress distribution law of the right-angled trapezoidalroadway in a gently inclined seam is similar to the numericalsimulation and the stress distribution of the surroundingrock in the roof the two walls the floor and the corner of theroadway shows clear asymmetric characteristics howeverthere are some differences in the numerical valuese mainreason is that the proportion of similar materials size of themodel loading mode and so on have an impact on the testresults
6 Comparison and Analysis ofSimulation Results
It can be seen from the simulation results that the asym-metric distribution law of the surrounding rock in inclinedright angle trapezoidal roadway is basically the same as thatof large dip angle and steep inclined coal seam roadway butthe degree of stress asymmetry in the inclined coal seam ismuch lower than that of large dip angle coal seam enumerical simulation results of the asymmetric deformationand failure characteristics of the inclined trapezoidal
roadway in the inclined coal seam are consistent with thelaboratory model test (Figure 16) and the site failuremorphology of the Shitanjing No 2 mine (Figure 17) inwhich the deformation and failure law exhibits an asym-metrical feature Further the two walls of the roadway areseverely bulging and the low side is larger than the high side
7 Conclusion
Based on the theory of asymmetric stress distribution in thesurrounding rock of right-angled trapezoidal roadway in aninclined coal seam and considering the Shijiajing No 2mining area as the engineering background this paperfurther analyzes the asymmetric distribution characteristicsof the surrounding rock by using the FLAC3D finite dif-ference method rough verifications with a simulationtest the following conclusions were drawn
(1) e stress distribution of the surrounding rock of theright-angled trapezoidal roadway in the inclined coalseam shows clear asymmetryemain performanceis that the peak value of stress concentration in thelow side is greater than that in the high side and thedistance between the high side and the side wall ofthe roadway is greater than that in the low side With
(a) (b)
Figure 16 Deformation and failure of roadway in laboratory model test (a) 24deg (b) 27deg
(a) (b)
Figure 17 Deformation and failure of roadway in Shitanjing No 2 mine (a) 24deg (b) 27deg
12 Advances in Civil Engineering
the increase in the inclination angle and groundstress the difference between the peak value of stressconcentration and the distance from the side wall ofthe roadway is more obvious When the inclinationangle is 18degndash27deg the peak value of stress concen-tration of the low side is 107ndash133 times that of thehigh side and the distance from the high side to theside wall of the roadway is 126ndash379m larger thanthat of the low side Second two sharp corners thatare symmetric with the same inclination angle of thecoal seam show obvious compressive stress regionswhile the opposite two sharp corners show obvioustensile stress regions e maximum values ofcompressive and tensile stresses appear on the roof ofthe roadway
(2) Under the action of asymmetric stress the defor-mation and failure of the roadway surrounding therock also presents asymmetric characteristics etwo walls of the roadway exhibit extrusion dislo-cation and serious deformation and damage how-ever the deformation damage of the low side isobviously larger than that at the high side e mainreason is that the difference in height between thetwo walls of the roadway leads to the uneven dis-tribution of stress
(3) e results of numerical simulation are basicallyconsistent with laboratory model test and field en-gineering However there are some differences in thedata obtained and the main reason is that the two areaffected by the selection of the simulation parame-ters ratio of similar materials size of the model andloading method
Data Availability
e data used to support the findings of this study are in-cluded within the article
Conflicts of Interest
e authors declare that they have no conflicts of interestregarding the publication of this paper
Acknowledgments
is study was financially supported by the National NaturalScience Foundation of China (51174159 and 59974019) theChina Postdoctoral Science Foundation (2015M572580)and the Scientific Research Plan Projects of EducationDepartment of Shanxi Province of China (15JK1471)
Supplementary Materials
eoretical analysis process of roof stress distribution ininclined coal seam roadway (Supplementary Materials)
References
[1] H C Li ldquoStudy on deformation and failure characteristicsand stability control of large dip angle thick compound roofroadwayrdquo Dissertation Taiyuan University of TechnologyTaiyuan China 2014
[2] e National Development and Reform Commission PeoplersquosRepublic of China Energy Development 11th Five-Year PlanBeijing China 2007 in Chinese
[3] K Yu L Zhou Q Cao and Z Li ldquoEvolutionary game re-search on symmetry of workersrsquo behavior in coal mine en-terprisesrdquo Symmetry vol 11 no 2 pp 156ndash168 2019
[4] L Si Z Wang R Xu C Tan X Liu and J Xu ldquoImageenhancement for surveillance video of coal mining face basedon single-scale retinex algorithm combined with bilateralfilteringrdquo Symmetry vol 9 no 6 pp 93ndash108 2017
[5] F L He M G Qian and C Y Liu Support System of Supportand Surrounding Rock for High Productivity and High Effi-ciency Working Face China Mining Industry Press XuzhouChina 1997 in Chinese
[6] S J Chen Y Wang Y Z Wu Z Wang and W J ZhangldquoCoal resources and development potential in northwestChinardquo Northwestern Geology vol 4 pp 40ndash56 2006 inChinese
[7] X M Sun and M C He ldquoNumerical simulation research oncoupling support theory of roadway within soft rock atdepthrdquo Journal of China University of Mining and Technologyvol 34 no 2 pp 166ndash169 2005 in Chinese
[8] S X Wei J H Song and H W Jing ldquoNumerical analysis ofstress in the surrounding rock of the dynamic pressure tunnelwith inclined seamsrdquo Metal Mine vol 41 no 3 pp 37ndash412012 in Chinese
[9] H Wang B Xia Y Lu T Gong and R Zhang ldquoStudy on thepropagation laws of hydrofractures meeting a faulted struc-ture in the coal seamrdquo Energies vol 10 no 5 pp 654ndash6722017
[10] J Xie J Xu and FWang ldquoMining-induced stress distributionof the working face in a kilometer-deep coal mine-a case studyin Tangshan coal minerdquo Journal of Geophysics and Engi-neering vol 15 no 5 pp 2060ndash2070 2018
[11] S Zhang X Wang G Fan D Zhang and C Jianbin ldquoPillarsize optimization design of isolated island panel gob-sideentry driving in deep inclined coal seam-case study ofPingmei No 6 coal seamrdquo Journal of Geophysics and Engi-neering vol 15 no 3 pp 816ndash828 2018
[12] Y Yuan S Tu F Wang X Zhang and B Li ldquoHydraulicsupport instability mechanism and its control in a fully-mechanized steep coal seam working face with large miningheightrdquo Journal of the Southern African Institute of Miningand Metallurgy vol 115 no 5 pp 441ndash447 2015
[13] J Sun L Wang and G Zhao ldquoFailure characteristics andconfined permeability of an inclined coal seam floor in fluid-solid couplingrdquo Advances in Civil Engineering vol 2018Article ID 2356390 12 pages 2018
[14] S Gu B Jiang G Wang H Dai and M Zhang ldquoOccurrencemechanism of roof-fall accidents in large-section coal seamroadways and related support design for Bayangaole coalmine Chinardquo Advances in Civil Engineering vol 2018 ArticleID 6831731 17 pages 2018
[15] H Xie M Gao R Zhang G Peng W Wang and A LildquoStudy on the mechanical properties andmechanical response
Advances in Civil Engineering 13
of coal mining at 1000m or deeperrdquo RockMechanics and RockEngineering vol 52 no 5 pp 1475ndash1490 2019
[16] Y Fang C Xu G Cui and B Kenneally ldquoScale model test ofhighway tunnel construction underlying mined-out thin coalseamrdquo Tunnelling and Underground Space Technology vol 56pp 105ndash116 2016
[17] M C He ldquoPhysical modeling of an underground roadwayexcavation in geologically 45deg inclined rock using infraredthermographyrdquo Engineering Geology vol 121 no 3-4pp 165ndash176 2011
[18] W Gong Y Peng M He and J Wang ldquoermal image andspectral characterization of roadway failure process in geo-logically 45deg inclined rocksrdquo Tunnelling and UndergroundSpace Technology vol 49 pp 156ndash173 2015
[19] H Yang S Cao Y Li C Sun and P Guo ldquoSoft roof failuremechanism and supporting method for gob-side entryretainingrdquo Minerals vol 5 no 4 pp 707ndash722 2015
[20] L Q Ma Y Zhang D S Zhang X Q Cao Q Q Li andY B Zhang ldquoSupport stability mechanism in a coal face withlarge angles in both strike and diprdquo Journal of the SouthernAfrican Institute of Mining and Metallurgy vol 115 no 7pp 599ndash606 2015
[21] M Jawed and R K Sinha ldquoDesign of rhombus coal pillars andsupport for roadway stability and mechanizing loading of facecoal using SDLs in a steeply inclined thin coal seammdashatechnical feasibility studyrdquo Arabian Journal of Geosciencesvol 11 no 15 pp 415ndash429 2018
[22] Y Yin J Zou Y Zhang Y Qiu and K Fang ldquoExperimentalstudy of the movement of backfilling gangues for goaf insteeply inclined coal seamsrdquo Arabian Journal of Geosciencesvol 11 no 12 pp 318ndash326 2018
[23] L Q Zhu and Y Zhang ldquoAnalysis of spontaneous com-bustion ldquothree zonesrdquo in 3237 working face of zhaogezhuangminerdquo Applied Mechanics and Materials vol 71ndash78pp 1978ndash1982 2011
[24] S Q He D Z Song Z L Li et al ldquoPrecursor of spatio-temporal evolution law of MS and AE activities for rock burstwarning in steeply inclined and extremely thick coal seamsunder caving mining conditionsrdquo Rock Mechanics and RockEngineering no 2 pp 1ndash21 2019
[25] H S Tu S H Tu Y Yuan F T Wang and Q S Bai ldquoPresentsituation of fully mechanized mining technology for steeplyinclined coal seams in Chinardquo Arabian Journal of Geosciencesvol 8 no 7 pp 1978ndash1982 2015
[26] W Lv Y Wu L Ming and J Yin ldquoMigration law of the roofof a composited backfilling longwall face in a steeply dippingcoal seamrdquo Minerals vol 9 no 3 pp 188ndash203 2019
[27] Z Bei S G Cao L G Wang and Y L Lu ldquoDeformationfailure mechanism and support measurements in roadway ofsteeply inclined coal seamrdquo Journal of Mining amp Safety En-gineering vol 28 no 2 pp 214ndash219 2011
[28] M Z Gao and H Q Jing ldquoMechanical analysis of asymmetricfloor heave of roadwayrdquo Journal of Anhui University of Scienceand Technology vol 32 no 4 pp 38ndash43 2012 in Chinese
[29] J G Liu A Y Cao Z M Yu G C Jing and H Y Liu ldquoStudyon stress characteristics of roadwayrsquos sides in deep and in-clined seamrdquo China Coal vol 42 no 8 pp 30ndash34 2016 inChinese
[30] X H Qi ldquoStudy on deformation characters and supportparameters of large angle seam roadway rock aroundrdquo Dis-sertation Xirsquoan University of Science and Technology XirsquoanChina 2015 in chinese
14 Advances in Civil Engineering
Displacement (m)
ndash50000E ndash 04ndash10000E ndash 03ndash15000E ndash 03ndash20000E ndash 03ndash22092E ndash 03
35007E ndash 03
30000E ndash 0335000E ndash 03
25000E ndash 0320000E ndash 0315000E ndash 0310000E ndash 0350000E ndash 0400000E + 00
(a)
Displacement (m)
ndash25000E ndash 04ndash50000E ndash 04ndash75000E ndash 04ndash10000E ndash 03ndash12500E ndash 03ndash12767E ndash 03
20000E ndash 0321873E ndash 03
15000E ndash 0317500E ndash 03
12500E ndash 0310000E ndash 0375000E ndash 0450000E ndash 0425000E ndash 0400000E + 00
(b)
Displacement (m)
ndash25000E ndash 04ndash50000E ndash 04ndash75000E ndash 04ndash10000E ndash 03ndash12500E ndash 03ndash15000E ndash 03ndash17500E ndash 03ndash18776E ndash 03
20000E ndash 03
15000E ndash 0317500E ndash 03
12500E ndash 0310000E ndash 03
26609E ndash 0325000E ndash 0322500E ndash 03
75000E ndash 0450000E ndash 0425000E ndash 0400000E + 00
(c)
Displacement (m)
ndash25000E ndash 04ndash50000E ndash 04ndash75000E ndash 04ndash10000E ndash 03ndash10040E ndash 03
15000E ndash 0316911E ndash 03
12500E ndash 0310000E ndash 0375000E ndash 0450000E ndash 0425000E ndash 0400000E + 00
(d)
Figure 9 Horizontal stress distribution characteristics of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
0 3 6 9 12 15 18 21 240
30
60
90
120
150
180
210
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)
(a)
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)0 3 6 9 12 15 18 21 24
0
30
60
90
120
150
180
(b)
Figure 10 Continued
Advances in Civil Engineering 7
(Figure 11)e geometric similarity ratio is 1 30 the modelsize is 72 cmtimes 72 cmtimes 10 cm and the lithology parametersare selected from the engineering background of the Shi-tanjing No 2 mining area which is the same as that for thenumerical simulation Different proportions of cementmortar were used to simulate the characteristics
e measurement points are arranged at the roadwaywalls roof and floor as well as the corners A verticaluniform load is applied to the model in a stepwise manneruntil the specimen is completely destroyede strain valuesof each measurement point under different loads arerecorded in real time during the loading process
52 Analysis of Test Results
521 Stress Distribution Law of the Roof Surrounding theRock Figure 12 displays a simulated ground stress-straincurve of the roof surrounding the rock of the trapezoidalroadway with different dip angles e stress of the roofsurrounding the rock of the roadway presents obviousasymmetric characteristics and the size distribution of themiddle measuring point of the roof (Intermediate)gt the lowside measuring point of the roof (R- low side)gt the high sidemeasuring point of the roof (R- high side) from Figure 12 Inaddition the maximum strain on the low side of the sur-rounding rock is significantly larger than that on the highside e greater the dip angle the more obvious the dif-ference in stress distribution between the high and low sides
of the surrounding rock of the roadway When the incli-nation angle is in the range of 18degndash27deg the maximum strainon the right wall of the roof (R- low side) is 13ndash21 timeslarger than that on the left wall of the roof (R- high side)
522 Stress Distribution Law of the Surrounding Rocks of theTwo Walls of the Roadway Figure 13 describes the simu-lated ground stress-strain curve of the surrounding rock ofthe right-angled trapezoidal roadway with different dipangles It can be concluded that the stress concentrations onthe two walls of the roadway are clearly different and theyincrease with increasing inclination and ground stress einclination angle is 18degndash27deg and the maximum value of theright wall (low side) stress concentration is 12ndash17 times thatof the left wall (high side)
523 Stress Distribution Law of the Two Surrounding RocksFigure 14 is a simulated ground stress-strain curve of thesurrounding rock at the corners of a right-angled trapezoidalroadway with different dip angles Figure 14 reveals that thestress distribution of each point at the four corners of theroadway is different From large to small the order is lowside shoulder angle (LSSA) high side shoulder angle(HSSA) low side bottom angle (LSBA) and high sidebottom angle (HSBA) When the dip angle is 18deg LSSArsquosstrain is 2ndash4 times of other sharp angles it changes with thechange in inclination
524 Analysis of Stress Distribution in the Surrounding Rockof the Roadway Floor Figure 15 is a simulated groundstress-strain curve of the surrounding rock of a rectangulartrapezoidal roadway with different dip angles It can be seenfrom Figure 15 that under the action of the upper roof andthe two sets of asymmetric stress the stress distribution ofthe floor of the roadway also exhibits obvious asymmetry
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)0 3 6 9 12 15 18 21 24
0
20
40
60
80
100
120
(c)
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)0 3 6 9 12 15 18 21 24
0
10
20
30
40
50
60
(d)
Figure 10 Analysis curves of the horizontal displacements of the two sides of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Table 3 Horizontal displacement of two sides of roadway (mm)
Dip angleGround stress 10MPa Ground stress 20MPaLow side High side Low side High side
18deg 2254 3747 11551 1925321deg 2389 3131 11464 1590024deg 1493 2301 7288 1068927deg 71 17 2141 5881
8 Advances in Civil Engineering
Data analysis
Computer
Strain gauge
Monitoring point
Loading
07m 01m
072
m
015m
01m
R-high side R-low sideIntermediate
LSSAHSSA
LSBAHSBA
High sideLow side
F-high side F-low side
Figure 11 Test models of the right-angled trapezoidal roadway
0
1
2
3
4
5
6
7
8
0 25 50 75 100 125 150 175Strain (10ndash6)
Stre
ss (M
Pa)
R-high sideIntermediateR-low side
(a)
Strain (10ndash6)
Stre
ss (M
Pa)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
7
0 30 60 90 120 150 180 210
(b)
Stre
ss (M
Pa)
Strain (10ndash6)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
0 40 80 120 160 200 240 280
(c)
Stre
ss (M
Pa)
Strain (10ndash6)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
0 50 100 150 200 250 300 350
(d)
Figure 12 Stress-strain curves of the roof surrounding the rock (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Advances in Civil Engineering 9
0
1
2
3
4
5
6
7
8
0 600 1200 1800 2400 3000
High sideLow side
Stre
ss (M
Pa)
Strain (10ndash6)
(a)
High sideLow side
0
1
2
3
4
5
6
7
0 300 600 900 1200 1500 1800
Stre
ss (M
Pa)
Strain (10ndash6)
(b)
0
1
2
3
4
5
6
0 800 1600 2400 3200
Stre
ss (M
Pa)
High sideLow side
Strain (10ndash6)
(c)
Stre
ss (M
Pa)
0
1
2
3
4
5
0 500 1000 1500 2000 2500
High sideLow side
Strain (10ndash6)
(d)
Figure 13 Stress-strain curve of the surrounding rock of the two sides of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
0
1
2
3
4
5
6
7
8
0 150 300 450 600 750 900
Stre
ss (M
Pa)
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(a)
Stre
ss (M
Pa)
0
1
2
3
4
5
6
7
0 200 400 600 800 1000 1200 1400
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(b)
Figure 14 Continued
10 Advances in Civil Engineering
Stre
ss (M
Pa)
0
1
2
3
4
5
6
0 200 400 600 800 1000 1200
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(c)
Stre
ss (M
Pa)
0
1
2
3
4
5
0 200 400 600 800 1000 1200 1400
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(d)
Figure 14 Stress-strain curve of the surrounding rock at the corner of the roadway (a) 18deg (b) 21deg (c) 27deg (d) 27deg
F-high sideF-low side
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
Stre
ss (M
Pa)
Strain (10ndash6)
(a)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
6
7
0 20 40 60 80 100 120 140 160Strain (10ndash6)
(b)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
6
0 30 60 90 120 150 180Strain (10ndash6)
(c)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
0 25 50 75 100 125Strain (10ndash6)
(d)
Figure 15 Stress-strain curve of roadway floor (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Advances in Civil Engineering 11
and the stress on the right wall of the floor (F-low side) isgreater than that on the left wall of the floor (F-high side)
From the laboratory model test results it can be seen thatthe stress distribution law of the right-angled trapezoidalroadway in a gently inclined seam is similar to the numericalsimulation and the stress distribution of the surroundingrock in the roof the two walls the floor and the corner of theroadway shows clear asymmetric characteristics howeverthere are some differences in the numerical valuese mainreason is that the proportion of similar materials size of themodel loading mode and so on have an impact on the testresults
6 Comparison and Analysis ofSimulation Results
It can be seen from the simulation results that the asym-metric distribution law of the surrounding rock in inclinedright angle trapezoidal roadway is basically the same as thatof large dip angle and steep inclined coal seam roadway butthe degree of stress asymmetry in the inclined coal seam ismuch lower than that of large dip angle coal seam enumerical simulation results of the asymmetric deformationand failure characteristics of the inclined trapezoidal
roadway in the inclined coal seam are consistent with thelaboratory model test (Figure 16) and the site failuremorphology of the Shitanjing No 2 mine (Figure 17) inwhich the deformation and failure law exhibits an asym-metrical feature Further the two walls of the roadway areseverely bulging and the low side is larger than the high side
7 Conclusion
Based on the theory of asymmetric stress distribution in thesurrounding rock of right-angled trapezoidal roadway in aninclined coal seam and considering the Shijiajing No 2mining area as the engineering background this paperfurther analyzes the asymmetric distribution characteristicsof the surrounding rock by using the FLAC3D finite dif-ference method rough verifications with a simulationtest the following conclusions were drawn
(1) e stress distribution of the surrounding rock of theright-angled trapezoidal roadway in the inclined coalseam shows clear asymmetryemain performanceis that the peak value of stress concentration in thelow side is greater than that in the high side and thedistance between the high side and the side wall ofthe roadway is greater than that in the low side With
(a) (b)
Figure 16 Deformation and failure of roadway in laboratory model test (a) 24deg (b) 27deg
(a) (b)
Figure 17 Deformation and failure of roadway in Shitanjing No 2 mine (a) 24deg (b) 27deg
12 Advances in Civil Engineering
the increase in the inclination angle and groundstress the difference between the peak value of stressconcentration and the distance from the side wall ofthe roadway is more obvious When the inclinationangle is 18degndash27deg the peak value of stress concen-tration of the low side is 107ndash133 times that of thehigh side and the distance from the high side to theside wall of the roadway is 126ndash379m larger thanthat of the low side Second two sharp corners thatare symmetric with the same inclination angle of thecoal seam show obvious compressive stress regionswhile the opposite two sharp corners show obvioustensile stress regions e maximum values ofcompressive and tensile stresses appear on the roof ofthe roadway
(2) Under the action of asymmetric stress the defor-mation and failure of the roadway surrounding therock also presents asymmetric characteristics etwo walls of the roadway exhibit extrusion dislo-cation and serious deformation and damage how-ever the deformation damage of the low side isobviously larger than that at the high side e mainreason is that the difference in height between thetwo walls of the roadway leads to the uneven dis-tribution of stress
(3) e results of numerical simulation are basicallyconsistent with laboratory model test and field en-gineering However there are some differences in thedata obtained and the main reason is that the two areaffected by the selection of the simulation parame-ters ratio of similar materials size of the model andloading method
Data Availability
e data used to support the findings of this study are in-cluded within the article
Conflicts of Interest
e authors declare that they have no conflicts of interestregarding the publication of this paper
Acknowledgments
is study was financially supported by the National NaturalScience Foundation of China (51174159 and 59974019) theChina Postdoctoral Science Foundation (2015M572580)and the Scientific Research Plan Projects of EducationDepartment of Shanxi Province of China (15JK1471)
Supplementary Materials
eoretical analysis process of roof stress distribution ininclined coal seam roadway (Supplementary Materials)
References
[1] H C Li ldquoStudy on deformation and failure characteristicsand stability control of large dip angle thick compound roofroadwayrdquo Dissertation Taiyuan University of TechnologyTaiyuan China 2014
[2] e National Development and Reform Commission PeoplersquosRepublic of China Energy Development 11th Five-Year PlanBeijing China 2007 in Chinese
[3] K Yu L Zhou Q Cao and Z Li ldquoEvolutionary game re-search on symmetry of workersrsquo behavior in coal mine en-terprisesrdquo Symmetry vol 11 no 2 pp 156ndash168 2019
[4] L Si Z Wang R Xu C Tan X Liu and J Xu ldquoImageenhancement for surveillance video of coal mining face basedon single-scale retinex algorithm combined with bilateralfilteringrdquo Symmetry vol 9 no 6 pp 93ndash108 2017
[5] F L He M G Qian and C Y Liu Support System of Supportand Surrounding Rock for High Productivity and High Effi-ciency Working Face China Mining Industry Press XuzhouChina 1997 in Chinese
[6] S J Chen Y Wang Y Z Wu Z Wang and W J ZhangldquoCoal resources and development potential in northwestChinardquo Northwestern Geology vol 4 pp 40ndash56 2006 inChinese
[7] X M Sun and M C He ldquoNumerical simulation research oncoupling support theory of roadway within soft rock atdepthrdquo Journal of China University of Mining and Technologyvol 34 no 2 pp 166ndash169 2005 in Chinese
[8] S X Wei J H Song and H W Jing ldquoNumerical analysis ofstress in the surrounding rock of the dynamic pressure tunnelwith inclined seamsrdquo Metal Mine vol 41 no 3 pp 37ndash412012 in Chinese
[9] H Wang B Xia Y Lu T Gong and R Zhang ldquoStudy on thepropagation laws of hydrofractures meeting a faulted struc-ture in the coal seamrdquo Energies vol 10 no 5 pp 654ndash6722017
[10] J Xie J Xu and FWang ldquoMining-induced stress distributionof the working face in a kilometer-deep coal mine-a case studyin Tangshan coal minerdquo Journal of Geophysics and Engi-neering vol 15 no 5 pp 2060ndash2070 2018
[11] S Zhang X Wang G Fan D Zhang and C Jianbin ldquoPillarsize optimization design of isolated island panel gob-sideentry driving in deep inclined coal seam-case study ofPingmei No 6 coal seamrdquo Journal of Geophysics and Engi-neering vol 15 no 3 pp 816ndash828 2018
[12] Y Yuan S Tu F Wang X Zhang and B Li ldquoHydraulicsupport instability mechanism and its control in a fully-mechanized steep coal seam working face with large miningheightrdquo Journal of the Southern African Institute of Miningand Metallurgy vol 115 no 5 pp 441ndash447 2015
[13] J Sun L Wang and G Zhao ldquoFailure characteristics andconfined permeability of an inclined coal seam floor in fluid-solid couplingrdquo Advances in Civil Engineering vol 2018Article ID 2356390 12 pages 2018
[14] S Gu B Jiang G Wang H Dai and M Zhang ldquoOccurrencemechanism of roof-fall accidents in large-section coal seamroadways and related support design for Bayangaole coalmine Chinardquo Advances in Civil Engineering vol 2018 ArticleID 6831731 17 pages 2018
[15] H Xie M Gao R Zhang G Peng W Wang and A LildquoStudy on the mechanical properties andmechanical response
Advances in Civil Engineering 13
of coal mining at 1000m or deeperrdquo RockMechanics and RockEngineering vol 52 no 5 pp 1475ndash1490 2019
[16] Y Fang C Xu G Cui and B Kenneally ldquoScale model test ofhighway tunnel construction underlying mined-out thin coalseamrdquo Tunnelling and Underground Space Technology vol 56pp 105ndash116 2016
[17] M C He ldquoPhysical modeling of an underground roadwayexcavation in geologically 45deg inclined rock using infraredthermographyrdquo Engineering Geology vol 121 no 3-4pp 165ndash176 2011
[18] W Gong Y Peng M He and J Wang ldquoermal image andspectral characterization of roadway failure process in geo-logically 45deg inclined rocksrdquo Tunnelling and UndergroundSpace Technology vol 49 pp 156ndash173 2015
[19] H Yang S Cao Y Li C Sun and P Guo ldquoSoft roof failuremechanism and supporting method for gob-side entryretainingrdquo Minerals vol 5 no 4 pp 707ndash722 2015
[20] L Q Ma Y Zhang D S Zhang X Q Cao Q Q Li andY B Zhang ldquoSupport stability mechanism in a coal face withlarge angles in both strike and diprdquo Journal of the SouthernAfrican Institute of Mining and Metallurgy vol 115 no 7pp 599ndash606 2015
[21] M Jawed and R K Sinha ldquoDesign of rhombus coal pillars andsupport for roadway stability and mechanizing loading of facecoal using SDLs in a steeply inclined thin coal seammdashatechnical feasibility studyrdquo Arabian Journal of Geosciencesvol 11 no 15 pp 415ndash429 2018
[22] Y Yin J Zou Y Zhang Y Qiu and K Fang ldquoExperimentalstudy of the movement of backfilling gangues for goaf insteeply inclined coal seamsrdquo Arabian Journal of Geosciencesvol 11 no 12 pp 318ndash326 2018
[23] L Q Zhu and Y Zhang ldquoAnalysis of spontaneous com-bustion ldquothree zonesrdquo in 3237 working face of zhaogezhuangminerdquo Applied Mechanics and Materials vol 71ndash78pp 1978ndash1982 2011
[24] S Q He D Z Song Z L Li et al ldquoPrecursor of spatio-temporal evolution law of MS and AE activities for rock burstwarning in steeply inclined and extremely thick coal seamsunder caving mining conditionsrdquo Rock Mechanics and RockEngineering no 2 pp 1ndash21 2019
[25] H S Tu S H Tu Y Yuan F T Wang and Q S Bai ldquoPresentsituation of fully mechanized mining technology for steeplyinclined coal seams in Chinardquo Arabian Journal of Geosciencesvol 8 no 7 pp 1978ndash1982 2015
[26] W Lv Y Wu L Ming and J Yin ldquoMigration law of the roofof a composited backfilling longwall face in a steeply dippingcoal seamrdquo Minerals vol 9 no 3 pp 188ndash203 2019
[27] Z Bei S G Cao L G Wang and Y L Lu ldquoDeformationfailure mechanism and support measurements in roadway ofsteeply inclined coal seamrdquo Journal of Mining amp Safety En-gineering vol 28 no 2 pp 214ndash219 2011
[28] M Z Gao and H Q Jing ldquoMechanical analysis of asymmetricfloor heave of roadwayrdquo Journal of Anhui University of Scienceand Technology vol 32 no 4 pp 38ndash43 2012 in Chinese
[29] J G Liu A Y Cao Z M Yu G C Jing and H Y Liu ldquoStudyon stress characteristics of roadwayrsquos sides in deep and in-clined seamrdquo China Coal vol 42 no 8 pp 30ndash34 2016 inChinese
[30] X H Qi ldquoStudy on deformation characters and supportparameters of large angle seam roadway rock aroundrdquo Dis-sertation Xirsquoan University of Science and Technology XirsquoanChina 2015 in chinese
14 Advances in Civil Engineering
(Figure 11)e geometric similarity ratio is 1 30 the modelsize is 72 cmtimes 72 cmtimes 10 cm and the lithology parametersare selected from the engineering background of the Shi-tanjing No 2 mining area which is the same as that for thenumerical simulation Different proportions of cementmortar were used to simulate the characteristics
e measurement points are arranged at the roadwaywalls roof and floor as well as the corners A verticaluniform load is applied to the model in a stepwise manneruntil the specimen is completely destroyede strain valuesof each measurement point under different loads arerecorded in real time during the loading process
52 Analysis of Test Results
521 Stress Distribution Law of the Roof Surrounding theRock Figure 12 displays a simulated ground stress-straincurve of the roof surrounding the rock of the trapezoidalroadway with different dip angles e stress of the roofsurrounding the rock of the roadway presents obviousasymmetric characteristics and the size distribution of themiddle measuring point of the roof (Intermediate)gt the lowside measuring point of the roof (R- low side)gt the high sidemeasuring point of the roof (R- high side) from Figure 12 Inaddition the maximum strain on the low side of the sur-rounding rock is significantly larger than that on the highside e greater the dip angle the more obvious the dif-ference in stress distribution between the high and low sides
of the surrounding rock of the roadway When the incli-nation angle is in the range of 18degndash27deg the maximum strainon the right wall of the roof (R- low side) is 13ndash21 timeslarger than that on the left wall of the roof (R- high side)
522 Stress Distribution Law of the Surrounding Rocks of theTwo Walls of the Roadway Figure 13 describes the simu-lated ground stress-strain curve of the surrounding rock ofthe right-angled trapezoidal roadway with different dipangles It can be concluded that the stress concentrations onthe two walls of the roadway are clearly different and theyincrease with increasing inclination and ground stress einclination angle is 18degndash27deg and the maximum value of theright wall (low side) stress concentration is 12ndash17 times thatof the left wall (high side)
523 Stress Distribution Law of the Two Surrounding RocksFigure 14 is a simulated ground stress-strain curve of thesurrounding rock at the corners of a right-angled trapezoidalroadway with different dip angles Figure 14 reveals that thestress distribution of each point at the four corners of theroadway is different From large to small the order is lowside shoulder angle (LSSA) high side shoulder angle(HSSA) low side bottom angle (LSBA) and high sidebottom angle (HSBA) When the dip angle is 18deg LSSArsquosstrain is 2ndash4 times of other sharp angles it changes with thechange in inclination
524 Analysis of Stress Distribution in the Surrounding Rockof the Roadway Floor Figure 15 is a simulated groundstress-strain curve of the surrounding rock of a rectangulartrapezoidal roadway with different dip angles It can be seenfrom Figure 15 that under the action of the upper roof andthe two sets of asymmetric stress the stress distribution ofthe floor of the roadway also exhibits obvious asymmetry
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)0 3 6 9 12 15 18 21 24
0
20
40
60
80
100
120
(c)
High sideLow side
Disp
lace
men
t (m
m)
q (MPa)0 3 6 9 12 15 18 21 24
0
10
20
30
40
50
60
(d)
Figure 10 Analysis curves of the horizontal displacements of the two sides of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Table 3 Horizontal displacement of two sides of roadway (mm)
Dip angleGround stress 10MPa Ground stress 20MPaLow side High side Low side High side
18deg 2254 3747 11551 1925321deg 2389 3131 11464 1590024deg 1493 2301 7288 1068927deg 71 17 2141 5881
8 Advances in Civil Engineering
Data analysis
Computer
Strain gauge
Monitoring point
Loading
07m 01m
072
m
015m
01m
R-high side R-low sideIntermediate
LSSAHSSA
LSBAHSBA
High sideLow side
F-high side F-low side
Figure 11 Test models of the right-angled trapezoidal roadway
0
1
2
3
4
5
6
7
8
0 25 50 75 100 125 150 175Strain (10ndash6)
Stre
ss (M
Pa)
R-high sideIntermediateR-low side
(a)
Strain (10ndash6)
Stre
ss (M
Pa)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
7
0 30 60 90 120 150 180 210
(b)
Stre
ss (M
Pa)
Strain (10ndash6)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
0 40 80 120 160 200 240 280
(c)
Stre
ss (M
Pa)
Strain (10ndash6)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
0 50 100 150 200 250 300 350
(d)
Figure 12 Stress-strain curves of the roof surrounding the rock (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Advances in Civil Engineering 9
0
1
2
3
4
5
6
7
8
0 600 1200 1800 2400 3000
High sideLow side
Stre
ss (M
Pa)
Strain (10ndash6)
(a)
High sideLow side
0
1
2
3
4
5
6
7
0 300 600 900 1200 1500 1800
Stre
ss (M
Pa)
Strain (10ndash6)
(b)
0
1
2
3
4
5
6
0 800 1600 2400 3200
Stre
ss (M
Pa)
High sideLow side
Strain (10ndash6)
(c)
Stre
ss (M
Pa)
0
1
2
3
4
5
0 500 1000 1500 2000 2500
High sideLow side
Strain (10ndash6)
(d)
Figure 13 Stress-strain curve of the surrounding rock of the two sides of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
0
1
2
3
4
5
6
7
8
0 150 300 450 600 750 900
Stre
ss (M
Pa)
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(a)
Stre
ss (M
Pa)
0
1
2
3
4
5
6
7
0 200 400 600 800 1000 1200 1400
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(b)
Figure 14 Continued
10 Advances in Civil Engineering
Stre
ss (M
Pa)
0
1
2
3
4
5
6
0 200 400 600 800 1000 1200
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(c)
Stre
ss (M
Pa)
0
1
2
3
4
5
0 200 400 600 800 1000 1200 1400
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(d)
Figure 14 Stress-strain curve of the surrounding rock at the corner of the roadway (a) 18deg (b) 21deg (c) 27deg (d) 27deg
F-high sideF-low side
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
Stre
ss (M
Pa)
Strain (10ndash6)
(a)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
6
7
0 20 40 60 80 100 120 140 160Strain (10ndash6)
(b)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
6
0 30 60 90 120 150 180Strain (10ndash6)
(c)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
0 25 50 75 100 125Strain (10ndash6)
(d)
Figure 15 Stress-strain curve of roadway floor (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Advances in Civil Engineering 11
and the stress on the right wall of the floor (F-low side) isgreater than that on the left wall of the floor (F-high side)
From the laboratory model test results it can be seen thatthe stress distribution law of the right-angled trapezoidalroadway in a gently inclined seam is similar to the numericalsimulation and the stress distribution of the surroundingrock in the roof the two walls the floor and the corner of theroadway shows clear asymmetric characteristics howeverthere are some differences in the numerical valuese mainreason is that the proportion of similar materials size of themodel loading mode and so on have an impact on the testresults
6 Comparison and Analysis ofSimulation Results
It can be seen from the simulation results that the asym-metric distribution law of the surrounding rock in inclinedright angle trapezoidal roadway is basically the same as thatof large dip angle and steep inclined coal seam roadway butthe degree of stress asymmetry in the inclined coal seam ismuch lower than that of large dip angle coal seam enumerical simulation results of the asymmetric deformationand failure characteristics of the inclined trapezoidal
roadway in the inclined coal seam are consistent with thelaboratory model test (Figure 16) and the site failuremorphology of the Shitanjing No 2 mine (Figure 17) inwhich the deformation and failure law exhibits an asym-metrical feature Further the two walls of the roadway areseverely bulging and the low side is larger than the high side
7 Conclusion
Based on the theory of asymmetric stress distribution in thesurrounding rock of right-angled trapezoidal roadway in aninclined coal seam and considering the Shijiajing No 2mining area as the engineering background this paperfurther analyzes the asymmetric distribution characteristicsof the surrounding rock by using the FLAC3D finite dif-ference method rough verifications with a simulationtest the following conclusions were drawn
(1) e stress distribution of the surrounding rock of theright-angled trapezoidal roadway in the inclined coalseam shows clear asymmetryemain performanceis that the peak value of stress concentration in thelow side is greater than that in the high side and thedistance between the high side and the side wall ofthe roadway is greater than that in the low side With
(a) (b)
Figure 16 Deformation and failure of roadway in laboratory model test (a) 24deg (b) 27deg
(a) (b)
Figure 17 Deformation and failure of roadway in Shitanjing No 2 mine (a) 24deg (b) 27deg
12 Advances in Civil Engineering
the increase in the inclination angle and groundstress the difference between the peak value of stressconcentration and the distance from the side wall ofthe roadway is more obvious When the inclinationangle is 18degndash27deg the peak value of stress concen-tration of the low side is 107ndash133 times that of thehigh side and the distance from the high side to theside wall of the roadway is 126ndash379m larger thanthat of the low side Second two sharp corners thatare symmetric with the same inclination angle of thecoal seam show obvious compressive stress regionswhile the opposite two sharp corners show obvioustensile stress regions e maximum values ofcompressive and tensile stresses appear on the roof ofthe roadway
(2) Under the action of asymmetric stress the defor-mation and failure of the roadway surrounding therock also presents asymmetric characteristics etwo walls of the roadway exhibit extrusion dislo-cation and serious deformation and damage how-ever the deformation damage of the low side isobviously larger than that at the high side e mainreason is that the difference in height between thetwo walls of the roadway leads to the uneven dis-tribution of stress
(3) e results of numerical simulation are basicallyconsistent with laboratory model test and field en-gineering However there are some differences in thedata obtained and the main reason is that the two areaffected by the selection of the simulation parame-ters ratio of similar materials size of the model andloading method
Data Availability
e data used to support the findings of this study are in-cluded within the article
Conflicts of Interest
e authors declare that they have no conflicts of interestregarding the publication of this paper
Acknowledgments
is study was financially supported by the National NaturalScience Foundation of China (51174159 and 59974019) theChina Postdoctoral Science Foundation (2015M572580)and the Scientific Research Plan Projects of EducationDepartment of Shanxi Province of China (15JK1471)
Supplementary Materials
eoretical analysis process of roof stress distribution ininclined coal seam roadway (Supplementary Materials)
References
[1] H C Li ldquoStudy on deformation and failure characteristicsand stability control of large dip angle thick compound roofroadwayrdquo Dissertation Taiyuan University of TechnologyTaiyuan China 2014
[2] e National Development and Reform Commission PeoplersquosRepublic of China Energy Development 11th Five-Year PlanBeijing China 2007 in Chinese
[3] K Yu L Zhou Q Cao and Z Li ldquoEvolutionary game re-search on symmetry of workersrsquo behavior in coal mine en-terprisesrdquo Symmetry vol 11 no 2 pp 156ndash168 2019
[4] L Si Z Wang R Xu C Tan X Liu and J Xu ldquoImageenhancement for surveillance video of coal mining face basedon single-scale retinex algorithm combined with bilateralfilteringrdquo Symmetry vol 9 no 6 pp 93ndash108 2017
[5] F L He M G Qian and C Y Liu Support System of Supportand Surrounding Rock for High Productivity and High Effi-ciency Working Face China Mining Industry Press XuzhouChina 1997 in Chinese
[6] S J Chen Y Wang Y Z Wu Z Wang and W J ZhangldquoCoal resources and development potential in northwestChinardquo Northwestern Geology vol 4 pp 40ndash56 2006 inChinese
[7] X M Sun and M C He ldquoNumerical simulation research oncoupling support theory of roadway within soft rock atdepthrdquo Journal of China University of Mining and Technologyvol 34 no 2 pp 166ndash169 2005 in Chinese
[8] S X Wei J H Song and H W Jing ldquoNumerical analysis ofstress in the surrounding rock of the dynamic pressure tunnelwith inclined seamsrdquo Metal Mine vol 41 no 3 pp 37ndash412012 in Chinese
[9] H Wang B Xia Y Lu T Gong and R Zhang ldquoStudy on thepropagation laws of hydrofractures meeting a faulted struc-ture in the coal seamrdquo Energies vol 10 no 5 pp 654ndash6722017
[10] J Xie J Xu and FWang ldquoMining-induced stress distributionof the working face in a kilometer-deep coal mine-a case studyin Tangshan coal minerdquo Journal of Geophysics and Engi-neering vol 15 no 5 pp 2060ndash2070 2018
[11] S Zhang X Wang G Fan D Zhang and C Jianbin ldquoPillarsize optimization design of isolated island panel gob-sideentry driving in deep inclined coal seam-case study ofPingmei No 6 coal seamrdquo Journal of Geophysics and Engi-neering vol 15 no 3 pp 816ndash828 2018
[12] Y Yuan S Tu F Wang X Zhang and B Li ldquoHydraulicsupport instability mechanism and its control in a fully-mechanized steep coal seam working face with large miningheightrdquo Journal of the Southern African Institute of Miningand Metallurgy vol 115 no 5 pp 441ndash447 2015
[13] J Sun L Wang and G Zhao ldquoFailure characteristics andconfined permeability of an inclined coal seam floor in fluid-solid couplingrdquo Advances in Civil Engineering vol 2018Article ID 2356390 12 pages 2018
[14] S Gu B Jiang G Wang H Dai and M Zhang ldquoOccurrencemechanism of roof-fall accidents in large-section coal seamroadways and related support design for Bayangaole coalmine Chinardquo Advances in Civil Engineering vol 2018 ArticleID 6831731 17 pages 2018
[15] H Xie M Gao R Zhang G Peng W Wang and A LildquoStudy on the mechanical properties andmechanical response
Advances in Civil Engineering 13
of coal mining at 1000m or deeperrdquo RockMechanics and RockEngineering vol 52 no 5 pp 1475ndash1490 2019
[16] Y Fang C Xu G Cui and B Kenneally ldquoScale model test ofhighway tunnel construction underlying mined-out thin coalseamrdquo Tunnelling and Underground Space Technology vol 56pp 105ndash116 2016
[17] M C He ldquoPhysical modeling of an underground roadwayexcavation in geologically 45deg inclined rock using infraredthermographyrdquo Engineering Geology vol 121 no 3-4pp 165ndash176 2011
[18] W Gong Y Peng M He and J Wang ldquoermal image andspectral characterization of roadway failure process in geo-logically 45deg inclined rocksrdquo Tunnelling and UndergroundSpace Technology vol 49 pp 156ndash173 2015
[19] H Yang S Cao Y Li C Sun and P Guo ldquoSoft roof failuremechanism and supporting method for gob-side entryretainingrdquo Minerals vol 5 no 4 pp 707ndash722 2015
[20] L Q Ma Y Zhang D S Zhang X Q Cao Q Q Li andY B Zhang ldquoSupport stability mechanism in a coal face withlarge angles in both strike and diprdquo Journal of the SouthernAfrican Institute of Mining and Metallurgy vol 115 no 7pp 599ndash606 2015
[21] M Jawed and R K Sinha ldquoDesign of rhombus coal pillars andsupport for roadway stability and mechanizing loading of facecoal using SDLs in a steeply inclined thin coal seammdashatechnical feasibility studyrdquo Arabian Journal of Geosciencesvol 11 no 15 pp 415ndash429 2018
[22] Y Yin J Zou Y Zhang Y Qiu and K Fang ldquoExperimentalstudy of the movement of backfilling gangues for goaf insteeply inclined coal seamsrdquo Arabian Journal of Geosciencesvol 11 no 12 pp 318ndash326 2018
[23] L Q Zhu and Y Zhang ldquoAnalysis of spontaneous com-bustion ldquothree zonesrdquo in 3237 working face of zhaogezhuangminerdquo Applied Mechanics and Materials vol 71ndash78pp 1978ndash1982 2011
[24] S Q He D Z Song Z L Li et al ldquoPrecursor of spatio-temporal evolution law of MS and AE activities for rock burstwarning in steeply inclined and extremely thick coal seamsunder caving mining conditionsrdquo Rock Mechanics and RockEngineering no 2 pp 1ndash21 2019
[25] H S Tu S H Tu Y Yuan F T Wang and Q S Bai ldquoPresentsituation of fully mechanized mining technology for steeplyinclined coal seams in Chinardquo Arabian Journal of Geosciencesvol 8 no 7 pp 1978ndash1982 2015
[26] W Lv Y Wu L Ming and J Yin ldquoMigration law of the roofof a composited backfilling longwall face in a steeply dippingcoal seamrdquo Minerals vol 9 no 3 pp 188ndash203 2019
[27] Z Bei S G Cao L G Wang and Y L Lu ldquoDeformationfailure mechanism and support measurements in roadway ofsteeply inclined coal seamrdquo Journal of Mining amp Safety En-gineering vol 28 no 2 pp 214ndash219 2011
[28] M Z Gao and H Q Jing ldquoMechanical analysis of asymmetricfloor heave of roadwayrdquo Journal of Anhui University of Scienceand Technology vol 32 no 4 pp 38ndash43 2012 in Chinese
[29] J G Liu A Y Cao Z M Yu G C Jing and H Y Liu ldquoStudyon stress characteristics of roadwayrsquos sides in deep and in-clined seamrdquo China Coal vol 42 no 8 pp 30ndash34 2016 inChinese
[30] X H Qi ldquoStudy on deformation characters and supportparameters of large angle seam roadway rock aroundrdquo Dis-sertation Xirsquoan University of Science and Technology XirsquoanChina 2015 in chinese
14 Advances in Civil Engineering
Data analysis
Computer
Strain gauge
Monitoring point
Loading
07m 01m
072
m
015m
01m
R-high side R-low sideIntermediate
LSSAHSSA
LSBAHSBA
High sideLow side
F-high side F-low side
Figure 11 Test models of the right-angled trapezoidal roadway
0
1
2
3
4
5
6
7
8
0 25 50 75 100 125 150 175Strain (10ndash6)
Stre
ss (M
Pa)
R-high sideIntermediateR-low side
(a)
Strain (10ndash6)
Stre
ss (M
Pa)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
7
0 30 60 90 120 150 180 210
(b)
Stre
ss (M
Pa)
Strain (10ndash6)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
0 40 80 120 160 200 240 280
(c)
Stre
ss (M
Pa)
Strain (10ndash6)
R-high sideIntermediateR-low side
0
1
2
3
4
5
6
0 50 100 150 200 250 300 350
(d)
Figure 12 Stress-strain curves of the roof surrounding the rock (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Advances in Civil Engineering 9
0
1
2
3
4
5
6
7
8
0 600 1200 1800 2400 3000
High sideLow side
Stre
ss (M
Pa)
Strain (10ndash6)
(a)
High sideLow side
0
1
2
3
4
5
6
7
0 300 600 900 1200 1500 1800
Stre
ss (M
Pa)
Strain (10ndash6)
(b)
0
1
2
3
4
5
6
0 800 1600 2400 3200
Stre
ss (M
Pa)
High sideLow side
Strain (10ndash6)
(c)
Stre
ss (M
Pa)
0
1
2
3
4
5
0 500 1000 1500 2000 2500
High sideLow side
Strain (10ndash6)
(d)
Figure 13 Stress-strain curve of the surrounding rock of the two sides of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
0
1
2
3
4
5
6
7
8
0 150 300 450 600 750 900
Stre
ss (M
Pa)
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(a)
Stre
ss (M
Pa)
0
1
2
3
4
5
6
7
0 200 400 600 800 1000 1200 1400
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(b)
Figure 14 Continued
10 Advances in Civil Engineering
Stre
ss (M
Pa)
0
1
2
3
4
5
6
0 200 400 600 800 1000 1200
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(c)
Stre
ss (M
Pa)
0
1
2
3
4
5
0 200 400 600 800 1000 1200 1400
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(d)
Figure 14 Stress-strain curve of the surrounding rock at the corner of the roadway (a) 18deg (b) 21deg (c) 27deg (d) 27deg
F-high sideF-low side
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
Stre
ss (M
Pa)
Strain (10ndash6)
(a)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
6
7
0 20 40 60 80 100 120 140 160Strain (10ndash6)
(b)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
6
0 30 60 90 120 150 180Strain (10ndash6)
(c)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
0 25 50 75 100 125Strain (10ndash6)
(d)
Figure 15 Stress-strain curve of roadway floor (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Advances in Civil Engineering 11
and the stress on the right wall of the floor (F-low side) isgreater than that on the left wall of the floor (F-high side)
From the laboratory model test results it can be seen thatthe stress distribution law of the right-angled trapezoidalroadway in a gently inclined seam is similar to the numericalsimulation and the stress distribution of the surroundingrock in the roof the two walls the floor and the corner of theroadway shows clear asymmetric characteristics howeverthere are some differences in the numerical valuese mainreason is that the proportion of similar materials size of themodel loading mode and so on have an impact on the testresults
6 Comparison and Analysis ofSimulation Results
It can be seen from the simulation results that the asym-metric distribution law of the surrounding rock in inclinedright angle trapezoidal roadway is basically the same as thatof large dip angle and steep inclined coal seam roadway butthe degree of stress asymmetry in the inclined coal seam ismuch lower than that of large dip angle coal seam enumerical simulation results of the asymmetric deformationand failure characteristics of the inclined trapezoidal
roadway in the inclined coal seam are consistent with thelaboratory model test (Figure 16) and the site failuremorphology of the Shitanjing No 2 mine (Figure 17) inwhich the deformation and failure law exhibits an asym-metrical feature Further the two walls of the roadway areseverely bulging and the low side is larger than the high side
7 Conclusion
Based on the theory of asymmetric stress distribution in thesurrounding rock of right-angled trapezoidal roadway in aninclined coal seam and considering the Shijiajing No 2mining area as the engineering background this paperfurther analyzes the asymmetric distribution characteristicsof the surrounding rock by using the FLAC3D finite dif-ference method rough verifications with a simulationtest the following conclusions were drawn
(1) e stress distribution of the surrounding rock of theright-angled trapezoidal roadway in the inclined coalseam shows clear asymmetryemain performanceis that the peak value of stress concentration in thelow side is greater than that in the high side and thedistance between the high side and the side wall ofthe roadway is greater than that in the low side With
(a) (b)
Figure 16 Deformation and failure of roadway in laboratory model test (a) 24deg (b) 27deg
(a) (b)
Figure 17 Deformation and failure of roadway in Shitanjing No 2 mine (a) 24deg (b) 27deg
12 Advances in Civil Engineering
the increase in the inclination angle and groundstress the difference between the peak value of stressconcentration and the distance from the side wall ofthe roadway is more obvious When the inclinationangle is 18degndash27deg the peak value of stress concen-tration of the low side is 107ndash133 times that of thehigh side and the distance from the high side to theside wall of the roadway is 126ndash379m larger thanthat of the low side Second two sharp corners thatare symmetric with the same inclination angle of thecoal seam show obvious compressive stress regionswhile the opposite two sharp corners show obvioustensile stress regions e maximum values ofcompressive and tensile stresses appear on the roof ofthe roadway
(2) Under the action of asymmetric stress the defor-mation and failure of the roadway surrounding therock also presents asymmetric characteristics etwo walls of the roadway exhibit extrusion dislo-cation and serious deformation and damage how-ever the deformation damage of the low side isobviously larger than that at the high side e mainreason is that the difference in height between thetwo walls of the roadway leads to the uneven dis-tribution of stress
(3) e results of numerical simulation are basicallyconsistent with laboratory model test and field en-gineering However there are some differences in thedata obtained and the main reason is that the two areaffected by the selection of the simulation parame-ters ratio of similar materials size of the model andloading method
Data Availability
e data used to support the findings of this study are in-cluded within the article
Conflicts of Interest
e authors declare that they have no conflicts of interestregarding the publication of this paper
Acknowledgments
is study was financially supported by the National NaturalScience Foundation of China (51174159 and 59974019) theChina Postdoctoral Science Foundation (2015M572580)and the Scientific Research Plan Projects of EducationDepartment of Shanxi Province of China (15JK1471)
Supplementary Materials
eoretical analysis process of roof stress distribution ininclined coal seam roadway (Supplementary Materials)
References
[1] H C Li ldquoStudy on deformation and failure characteristicsand stability control of large dip angle thick compound roofroadwayrdquo Dissertation Taiyuan University of TechnologyTaiyuan China 2014
[2] e National Development and Reform Commission PeoplersquosRepublic of China Energy Development 11th Five-Year PlanBeijing China 2007 in Chinese
[3] K Yu L Zhou Q Cao and Z Li ldquoEvolutionary game re-search on symmetry of workersrsquo behavior in coal mine en-terprisesrdquo Symmetry vol 11 no 2 pp 156ndash168 2019
[4] L Si Z Wang R Xu C Tan X Liu and J Xu ldquoImageenhancement for surveillance video of coal mining face basedon single-scale retinex algorithm combined with bilateralfilteringrdquo Symmetry vol 9 no 6 pp 93ndash108 2017
[5] F L He M G Qian and C Y Liu Support System of Supportand Surrounding Rock for High Productivity and High Effi-ciency Working Face China Mining Industry Press XuzhouChina 1997 in Chinese
[6] S J Chen Y Wang Y Z Wu Z Wang and W J ZhangldquoCoal resources and development potential in northwestChinardquo Northwestern Geology vol 4 pp 40ndash56 2006 inChinese
[7] X M Sun and M C He ldquoNumerical simulation research oncoupling support theory of roadway within soft rock atdepthrdquo Journal of China University of Mining and Technologyvol 34 no 2 pp 166ndash169 2005 in Chinese
[8] S X Wei J H Song and H W Jing ldquoNumerical analysis ofstress in the surrounding rock of the dynamic pressure tunnelwith inclined seamsrdquo Metal Mine vol 41 no 3 pp 37ndash412012 in Chinese
[9] H Wang B Xia Y Lu T Gong and R Zhang ldquoStudy on thepropagation laws of hydrofractures meeting a faulted struc-ture in the coal seamrdquo Energies vol 10 no 5 pp 654ndash6722017
[10] J Xie J Xu and FWang ldquoMining-induced stress distributionof the working face in a kilometer-deep coal mine-a case studyin Tangshan coal minerdquo Journal of Geophysics and Engi-neering vol 15 no 5 pp 2060ndash2070 2018
[11] S Zhang X Wang G Fan D Zhang and C Jianbin ldquoPillarsize optimization design of isolated island panel gob-sideentry driving in deep inclined coal seam-case study ofPingmei No 6 coal seamrdquo Journal of Geophysics and Engi-neering vol 15 no 3 pp 816ndash828 2018
[12] Y Yuan S Tu F Wang X Zhang and B Li ldquoHydraulicsupport instability mechanism and its control in a fully-mechanized steep coal seam working face with large miningheightrdquo Journal of the Southern African Institute of Miningand Metallurgy vol 115 no 5 pp 441ndash447 2015
[13] J Sun L Wang and G Zhao ldquoFailure characteristics andconfined permeability of an inclined coal seam floor in fluid-solid couplingrdquo Advances in Civil Engineering vol 2018Article ID 2356390 12 pages 2018
[14] S Gu B Jiang G Wang H Dai and M Zhang ldquoOccurrencemechanism of roof-fall accidents in large-section coal seamroadways and related support design for Bayangaole coalmine Chinardquo Advances in Civil Engineering vol 2018 ArticleID 6831731 17 pages 2018
[15] H Xie M Gao R Zhang G Peng W Wang and A LildquoStudy on the mechanical properties andmechanical response
Advances in Civil Engineering 13
of coal mining at 1000m or deeperrdquo RockMechanics and RockEngineering vol 52 no 5 pp 1475ndash1490 2019
[16] Y Fang C Xu G Cui and B Kenneally ldquoScale model test ofhighway tunnel construction underlying mined-out thin coalseamrdquo Tunnelling and Underground Space Technology vol 56pp 105ndash116 2016
[17] M C He ldquoPhysical modeling of an underground roadwayexcavation in geologically 45deg inclined rock using infraredthermographyrdquo Engineering Geology vol 121 no 3-4pp 165ndash176 2011
[18] W Gong Y Peng M He and J Wang ldquoermal image andspectral characterization of roadway failure process in geo-logically 45deg inclined rocksrdquo Tunnelling and UndergroundSpace Technology vol 49 pp 156ndash173 2015
[19] H Yang S Cao Y Li C Sun and P Guo ldquoSoft roof failuremechanism and supporting method for gob-side entryretainingrdquo Minerals vol 5 no 4 pp 707ndash722 2015
[20] L Q Ma Y Zhang D S Zhang X Q Cao Q Q Li andY B Zhang ldquoSupport stability mechanism in a coal face withlarge angles in both strike and diprdquo Journal of the SouthernAfrican Institute of Mining and Metallurgy vol 115 no 7pp 599ndash606 2015
[21] M Jawed and R K Sinha ldquoDesign of rhombus coal pillars andsupport for roadway stability and mechanizing loading of facecoal using SDLs in a steeply inclined thin coal seammdashatechnical feasibility studyrdquo Arabian Journal of Geosciencesvol 11 no 15 pp 415ndash429 2018
[22] Y Yin J Zou Y Zhang Y Qiu and K Fang ldquoExperimentalstudy of the movement of backfilling gangues for goaf insteeply inclined coal seamsrdquo Arabian Journal of Geosciencesvol 11 no 12 pp 318ndash326 2018
[23] L Q Zhu and Y Zhang ldquoAnalysis of spontaneous com-bustion ldquothree zonesrdquo in 3237 working face of zhaogezhuangminerdquo Applied Mechanics and Materials vol 71ndash78pp 1978ndash1982 2011
[24] S Q He D Z Song Z L Li et al ldquoPrecursor of spatio-temporal evolution law of MS and AE activities for rock burstwarning in steeply inclined and extremely thick coal seamsunder caving mining conditionsrdquo Rock Mechanics and RockEngineering no 2 pp 1ndash21 2019
[25] H S Tu S H Tu Y Yuan F T Wang and Q S Bai ldquoPresentsituation of fully mechanized mining technology for steeplyinclined coal seams in Chinardquo Arabian Journal of Geosciencesvol 8 no 7 pp 1978ndash1982 2015
[26] W Lv Y Wu L Ming and J Yin ldquoMigration law of the roofof a composited backfilling longwall face in a steeply dippingcoal seamrdquo Minerals vol 9 no 3 pp 188ndash203 2019
[27] Z Bei S G Cao L G Wang and Y L Lu ldquoDeformationfailure mechanism and support measurements in roadway ofsteeply inclined coal seamrdquo Journal of Mining amp Safety En-gineering vol 28 no 2 pp 214ndash219 2011
[28] M Z Gao and H Q Jing ldquoMechanical analysis of asymmetricfloor heave of roadwayrdquo Journal of Anhui University of Scienceand Technology vol 32 no 4 pp 38ndash43 2012 in Chinese
[29] J G Liu A Y Cao Z M Yu G C Jing and H Y Liu ldquoStudyon stress characteristics of roadwayrsquos sides in deep and in-clined seamrdquo China Coal vol 42 no 8 pp 30ndash34 2016 inChinese
[30] X H Qi ldquoStudy on deformation characters and supportparameters of large angle seam roadway rock aroundrdquo Dis-sertation Xirsquoan University of Science and Technology XirsquoanChina 2015 in chinese
14 Advances in Civil Engineering
0
1
2
3
4
5
6
7
8
0 600 1200 1800 2400 3000
High sideLow side
Stre
ss (M
Pa)
Strain (10ndash6)
(a)
High sideLow side
0
1
2
3
4
5
6
7
0 300 600 900 1200 1500 1800
Stre
ss (M
Pa)
Strain (10ndash6)
(b)
0
1
2
3
4
5
6
0 800 1600 2400 3200
Stre
ss (M
Pa)
High sideLow side
Strain (10ndash6)
(c)
Stre
ss (M
Pa)
0
1
2
3
4
5
0 500 1000 1500 2000 2500
High sideLow side
Strain (10ndash6)
(d)
Figure 13 Stress-strain curve of the surrounding rock of the two sides of the roadway (a) 18deg (b) 21deg (c) 24deg (d) 27deg
0
1
2
3
4
5
6
7
8
0 150 300 450 600 750 900
Stre
ss (M
Pa)
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(a)
Stre
ss (M
Pa)
0
1
2
3
4
5
6
7
0 200 400 600 800 1000 1200 1400
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(b)
Figure 14 Continued
10 Advances in Civil Engineering
Stre
ss (M
Pa)
0
1
2
3
4
5
6
0 200 400 600 800 1000 1200
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(c)
Stre
ss (M
Pa)
0
1
2
3
4
5
0 200 400 600 800 1000 1200 1400
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(d)
Figure 14 Stress-strain curve of the surrounding rock at the corner of the roadway (a) 18deg (b) 21deg (c) 27deg (d) 27deg
F-high sideF-low side
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
Stre
ss (M
Pa)
Strain (10ndash6)
(a)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
6
7
0 20 40 60 80 100 120 140 160Strain (10ndash6)
(b)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
6
0 30 60 90 120 150 180Strain (10ndash6)
(c)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
0 25 50 75 100 125Strain (10ndash6)
(d)
Figure 15 Stress-strain curve of roadway floor (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Advances in Civil Engineering 11
and the stress on the right wall of the floor (F-low side) isgreater than that on the left wall of the floor (F-high side)
From the laboratory model test results it can be seen thatthe stress distribution law of the right-angled trapezoidalroadway in a gently inclined seam is similar to the numericalsimulation and the stress distribution of the surroundingrock in the roof the two walls the floor and the corner of theroadway shows clear asymmetric characteristics howeverthere are some differences in the numerical valuese mainreason is that the proportion of similar materials size of themodel loading mode and so on have an impact on the testresults
6 Comparison and Analysis ofSimulation Results
It can be seen from the simulation results that the asym-metric distribution law of the surrounding rock in inclinedright angle trapezoidal roadway is basically the same as thatof large dip angle and steep inclined coal seam roadway butthe degree of stress asymmetry in the inclined coal seam ismuch lower than that of large dip angle coal seam enumerical simulation results of the asymmetric deformationand failure characteristics of the inclined trapezoidal
roadway in the inclined coal seam are consistent with thelaboratory model test (Figure 16) and the site failuremorphology of the Shitanjing No 2 mine (Figure 17) inwhich the deformation and failure law exhibits an asym-metrical feature Further the two walls of the roadway areseverely bulging and the low side is larger than the high side
7 Conclusion
Based on the theory of asymmetric stress distribution in thesurrounding rock of right-angled trapezoidal roadway in aninclined coal seam and considering the Shijiajing No 2mining area as the engineering background this paperfurther analyzes the asymmetric distribution characteristicsof the surrounding rock by using the FLAC3D finite dif-ference method rough verifications with a simulationtest the following conclusions were drawn
(1) e stress distribution of the surrounding rock of theright-angled trapezoidal roadway in the inclined coalseam shows clear asymmetryemain performanceis that the peak value of stress concentration in thelow side is greater than that in the high side and thedistance between the high side and the side wall ofthe roadway is greater than that in the low side With
(a) (b)
Figure 16 Deformation and failure of roadway in laboratory model test (a) 24deg (b) 27deg
(a) (b)
Figure 17 Deformation and failure of roadway in Shitanjing No 2 mine (a) 24deg (b) 27deg
12 Advances in Civil Engineering
the increase in the inclination angle and groundstress the difference between the peak value of stressconcentration and the distance from the side wall ofthe roadway is more obvious When the inclinationangle is 18degndash27deg the peak value of stress concen-tration of the low side is 107ndash133 times that of thehigh side and the distance from the high side to theside wall of the roadway is 126ndash379m larger thanthat of the low side Second two sharp corners thatare symmetric with the same inclination angle of thecoal seam show obvious compressive stress regionswhile the opposite two sharp corners show obvioustensile stress regions e maximum values ofcompressive and tensile stresses appear on the roof ofthe roadway
(2) Under the action of asymmetric stress the defor-mation and failure of the roadway surrounding therock also presents asymmetric characteristics etwo walls of the roadway exhibit extrusion dislo-cation and serious deformation and damage how-ever the deformation damage of the low side isobviously larger than that at the high side e mainreason is that the difference in height between thetwo walls of the roadway leads to the uneven dis-tribution of stress
(3) e results of numerical simulation are basicallyconsistent with laboratory model test and field en-gineering However there are some differences in thedata obtained and the main reason is that the two areaffected by the selection of the simulation parame-ters ratio of similar materials size of the model andloading method
Data Availability
e data used to support the findings of this study are in-cluded within the article
Conflicts of Interest
e authors declare that they have no conflicts of interestregarding the publication of this paper
Acknowledgments
is study was financially supported by the National NaturalScience Foundation of China (51174159 and 59974019) theChina Postdoctoral Science Foundation (2015M572580)and the Scientific Research Plan Projects of EducationDepartment of Shanxi Province of China (15JK1471)
Supplementary Materials
eoretical analysis process of roof stress distribution ininclined coal seam roadway (Supplementary Materials)
References
[1] H C Li ldquoStudy on deformation and failure characteristicsand stability control of large dip angle thick compound roofroadwayrdquo Dissertation Taiyuan University of TechnologyTaiyuan China 2014
[2] e National Development and Reform Commission PeoplersquosRepublic of China Energy Development 11th Five-Year PlanBeijing China 2007 in Chinese
[3] K Yu L Zhou Q Cao and Z Li ldquoEvolutionary game re-search on symmetry of workersrsquo behavior in coal mine en-terprisesrdquo Symmetry vol 11 no 2 pp 156ndash168 2019
[4] L Si Z Wang R Xu C Tan X Liu and J Xu ldquoImageenhancement for surveillance video of coal mining face basedon single-scale retinex algorithm combined with bilateralfilteringrdquo Symmetry vol 9 no 6 pp 93ndash108 2017
[5] F L He M G Qian and C Y Liu Support System of Supportand Surrounding Rock for High Productivity and High Effi-ciency Working Face China Mining Industry Press XuzhouChina 1997 in Chinese
[6] S J Chen Y Wang Y Z Wu Z Wang and W J ZhangldquoCoal resources and development potential in northwestChinardquo Northwestern Geology vol 4 pp 40ndash56 2006 inChinese
[7] X M Sun and M C He ldquoNumerical simulation research oncoupling support theory of roadway within soft rock atdepthrdquo Journal of China University of Mining and Technologyvol 34 no 2 pp 166ndash169 2005 in Chinese
[8] S X Wei J H Song and H W Jing ldquoNumerical analysis ofstress in the surrounding rock of the dynamic pressure tunnelwith inclined seamsrdquo Metal Mine vol 41 no 3 pp 37ndash412012 in Chinese
[9] H Wang B Xia Y Lu T Gong and R Zhang ldquoStudy on thepropagation laws of hydrofractures meeting a faulted struc-ture in the coal seamrdquo Energies vol 10 no 5 pp 654ndash6722017
[10] J Xie J Xu and FWang ldquoMining-induced stress distributionof the working face in a kilometer-deep coal mine-a case studyin Tangshan coal minerdquo Journal of Geophysics and Engi-neering vol 15 no 5 pp 2060ndash2070 2018
[11] S Zhang X Wang G Fan D Zhang and C Jianbin ldquoPillarsize optimization design of isolated island panel gob-sideentry driving in deep inclined coal seam-case study ofPingmei No 6 coal seamrdquo Journal of Geophysics and Engi-neering vol 15 no 3 pp 816ndash828 2018
[12] Y Yuan S Tu F Wang X Zhang and B Li ldquoHydraulicsupport instability mechanism and its control in a fully-mechanized steep coal seam working face with large miningheightrdquo Journal of the Southern African Institute of Miningand Metallurgy vol 115 no 5 pp 441ndash447 2015
[13] J Sun L Wang and G Zhao ldquoFailure characteristics andconfined permeability of an inclined coal seam floor in fluid-solid couplingrdquo Advances in Civil Engineering vol 2018Article ID 2356390 12 pages 2018
[14] S Gu B Jiang G Wang H Dai and M Zhang ldquoOccurrencemechanism of roof-fall accidents in large-section coal seamroadways and related support design for Bayangaole coalmine Chinardquo Advances in Civil Engineering vol 2018 ArticleID 6831731 17 pages 2018
[15] H Xie M Gao R Zhang G Peng W Wang and A LildquoStudy on the mechanical properties andmechanical response
Advances in Civil Engineering 13
of coal mining at 1000m or deeperrdquo RockMechanics and RockEngineering vol 52 no 5 pp 1475ndash1490 2019
[16] Y Fang C Xu G Cui and B Kenneally ldquoScale model test ofhighway tunnel construction underlying mined-out thin coalseamrdquo Tunnelling and Underground Space Technology vol 56pp 105ndash116 2016
[17] M C He ldquoPhysical modeling of an underground roadwayexcavation in geologically 45deg inclined rock using infraredthermographyrdquo Engineering Geology vol 121 no 3-4pp 165ndash176 2011
[18] W Gong Y Peng M He and J Wang ldquoermal image andspectral characterization of roadway failure process in geo-logically 45deg inclined rocksrdquo Tunnelling and UndergroundSpace Technology vol 49 pp 156ndash173 2015
[19] H Yang S Cao Y Li C Sun and P Guo ldquoSoft roof failuremechanism and supporting method for gob-side entryretainingrdquo Minerals vol 5 no 4 pp 707ndash722 2015
[20] L Q Ma Y Zhang D S Zhang X Q Cao Q Q Li andY B Zhang ldquoSupport stability mechanism in a coal face withlarge angles in both strike and diprdquo Journal of the SouthernAfrican Institute of Mining and Metallurgy vol 115 no 7pp 599ndash606 2015
[21] M Jawed and R K Sinha ldquoDesign of rhombus coal pillars andsupport for roadway stability and mechanizing loading of facecoal using SDLs in a steeply inclined thin coal seammdashatechnical feasibility studyrdquo Arabian Journal of Geosciencesvol 11 no 15 pp 415ndash429 2018
[22] Y Yin J Zou Y Zhang Y Qiu and K Fang ldquoExperimentalstudy of the movement of backfilling gangues for goaf insteeply inclined coal seamsrdquo Arabian Journal of Geosciencesvol 11 no 12 pp 318ndash326 2018
[23] L Q Zhu and Y Zhang ldquoAnalysis of spontaneous com-bustion ldquothree zonesrdquo in 3237 working face of zhaogezhuangminerdquo Applied Mechanics and Materials vol 71ndash78pp 1978ndash1982 2011
[24] S Q He D Z Song Z L Li et al ldquoPrecursor of spatio-temporal evolution law of MS and AE activities for rock burstwarning in steeply inclined and extremely thick coal seamsunder caving mining conditionsrdquo Rock Mechanics and RockEngineering no 2 pp 1ndash21 2019
[25] H S Tu S H Tu Y Yuan F T Wang and Q S Bai ldquoPresentsituation of fully mechanized mining technology for steeplyinclined coal seams in Chinardquo Arabian Journal of Geosciencesvol 8 no 7 pp 1978ndash1982 2015
[26] W Lv Y Wu L Ming and J Yin ldquoMigration law of the roofof a composited backfilling longwall face in a steeply dippingcoal seamrdquo Minerals vol 9 no 3 pp 188ndash203 2019
[27] Z Bei S G Cao L G Wang and Y L Lu ldquoDeformationfailure mechanism and support measurements in roadway ofsteeply inclined coal seamrdquo Journal of Mining amp Safety En-gineering vol 28 no 2 pp 214ndash219 2011
[28] M Z Gao and H Q Jing ldquoMechanical analysis of asymmetricfloor heave of roadwayrdquo Journal of Anhui University of Scienceand Technology vol 32 no 4 pp 38ndash43 2012 in Chinese
[29] J G Liu A Y Cao Z M Yu G C Jing and H Y Liu ldquoStudyon stress characteristics of roadwayrsquos sides in deep and in-clined seamrdquo China Coal vol 42 no 8 pp 30ndash34 2016 inChinese
[30] X H Qi ldquoStudy on deformation characters and supportparameters of large angle seam roadway rock aroundrdquo Dis-sertation Xirsquoan University of Science and Technology XirsquoanChina 2015 in chinese
14 Advances in Civil Engineering
Stre
ss (M
Pa)
0
1
2
3
4
5
6
0 200 400 600 800 1000 1200
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(c)
Stre
ss (M
Pa)
0
1
2
3
4
5
0 200 400 600 800 1000 1200 1400
HSSA LSSA
HSBALSBA
Strain (10ndash6)
(d)
Figure 14 Stress-strain curve of the surrounding rock at the corner of the roadway (a) 18deg (b) 21deg (c) 27deg (d) 27deg
F-high sideF-low side
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
Stre
ss (M
Pa)
Strain (10ndash6)
(a)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
6
7
0 20 40 60 80 100 120 140 160Strain (10ndash6)
(b)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
6
0 30 60 90 120 150 180Strain (10ndash6)
(c)
F-high sideF-low side
Stre
ss (M
Pa)
0
1
2
3
4
5
0 25 50 75 100 125Strain (10ndash6)
(d)
Figure 15 Stress-strain curve of roadway floor (a) 18deg (b) 21deg (c) 24deg (d) 27deg
Advances in Civil Engineering 11
and the stress on the right wall of the floor (F-low side) isgreater than that on the left wall of the floor (F-high side)
From the laboratory model test results it can be seen thatthe stress distribution law of the right-angled trapezoidalroadway in a gently inclined seam is similar to the numericalsimulation and the stress distribution of the surroundingrock in the roof the two walls the floor and the corner of theroadway shows clear asymmetric characteristics howeverthere are some differences in the numerical valuese mainreason is that the proportion of similar materials size of themodel loading mode and so on have an impact on the testresults
6 Comparison and Analysis ofSimulation Results
It can be seen from the simulation results that the asym-metric distribution law of the surrounding rock in inclinedright angle trapezoidal roadway is basically the same as thatof large dip angle and steep inclined coal seam roadway butthe degree of stress asymmetry in the inclined coal seam ismuch lower than that of large dip angle coal seam enumerical simulation results of the asymmetric deformationand failure characteristics of the inclined trapezoidal
roadway in the inclined coal seam are consistent with thelaboratory model test (Figure 16) and the site failuremorphology of the Shitanjing No 2 mine (Figure 17) inwhich the deformation and failure law exhibits an asym-metrical feature Further the two walls of the roadway areseverely bulging and the low side is larger than the high side
7 Conclusion
Based on the theory of asymmetric stress distribution in thesurrounding rock of right-angled trapezoidal roadway in aninclined coal seam and considering the Shijiajing No 2mining area as the engineering background this paperfurther analyzes the asymmetric distribution characteristicsof the surrounding rock by using the FLAC3D finite dif-ference method rough verifications with a simulationtest the following conclusions were drawn
(1) e stress distribution of the surrounding rock of theright-angled trapezoidal roadway in the inclined coalseam shows clear asymmetryemain performanceis that the peak value of stress concentration in thelow side is greater than that in the high side and thedistance between the high side and the side wall ofthe roadway is greater than that in the low side With
(a) (b)
Figure 16 Deformation and failure of roadway in laboratory model test (a) 24deg (b) 27deg
(a) (b)
Figure 17 Deformation and failure of roadway in Shitanjing No 2 mine (a) 24deg (b) 27deg
12 Advances in Civil Engineering
the increase in the inclination angle and groundstress the difference between the peak value of stressconcentration and the distance from the side wall ofthe roadway is more obvious When the inclinationangle is 18degndash27deg the peak value of stress concen-tration of the low side is 107ndash133 times that of thehigh side and the distance from the high side to theside wall of the roadway is 126ndash379m larger thanthat of the low side Second two sharp corners thatare symmetric with the same inclination angle of thecoal seam show obvious compressive stress regionswhile the opposite two sharp corners show obvioustensile stress regions e maximum values ofcompressive and tensile stresses appear on the roof ofthe roadway
(2) Under the action of asymmetric stress the defor-mation and failure of the roadway surrounding therock also presents asymmetric characteristics etwo walls of the roadway exhibit extrusion dislo-cation and serious deformation and damage how-ever the deformation damage of the low side isobviously larger than that at the high side e mainreason is that the difference in height between thetwo walls of the roadway leads to the uneven dis-tribution of stress
(3) e results of numerical simulation are basicallyconsistent with laboratory model test and field en-gineering However there are some differences in thedata obtained and the main reason is that the two areaffected by the selection of the simulation parame-ters ratio of similar materials size of the model andloading method
Data Availability
e data used to support the findings of this study are in-cluded within the article
Conflicts of Interest
e authors declare that they have no conflicts of interestregarding the publication of this paper
Acknowledgments
is study was financially supported by the National NaturalScience Foundation of China (51174159 and 59974019) theChina Postdoctoral Science Foundation (2015M572580)and the Scientific Research Plan Projects of EducationDepartment of Shanxi Province of China (15JK1471)
Supplementary Materials
eoretical analysis process of roof stress distribution ininclined coal seam roadway (Supplementary Materials)
References
[1] H C Li ldquoStudy on deformation and failure characteristicsand stability control of large dip angle thick compound roofroadwayrdquo Dissertation Taiyuan University of TechnologyTaiyuan China 2014
[2] e National Development and Reform Commission PeoplersquosRepublic of China Energy Development 11th Five-Year PlanBeijing China 2007 in Chinese
[3] K Yu L Zhou Q Cao and Z Li ldquoEvolutionary game re-search on symmetry of workersrsquo behavior in coal mine en-terprisesrdquo Symmetry vol 11 no 2 pp 156ndash168 2019
[4] L Si Z Wang R Xu C Tan X Liu and J Xu ldquoImageenhancement for surveillance video of coal mining face basedon single-scale retinex algorithm combined with bilateralfilteringrdquo Symmetry vol 9 no 6 pp 93ndash108 2017
[5] F L He M G Qian and C Y Liu Support System of Supportand Surrounding Rock for High Productivity and High Effi-ciency Working Face China Mining Industry Press XuzhouChina 1997 in Chinese
[6] S J Chen Y Wang Y Z Wu Z Wang and W J ZhangldquoCoal resources and development potential in northwestChinardquo Northwestern Geology vol 4 pp 40ndash56 2006 inChinese
[7] X M Sun and M C He ldquoNumerical simulation research oncoupling support theory of roadway within soft rock atdepthrdquo Journal of China University of Mining and Technologyvol 34 no 2 pp 166ndash169 2005 in Chinese
[8] S X Wei J H Song and H W Jing ldquoNumerical analysis ofstress in the surrounding rock of the dynamic pressure tunnelwith inclined seamsrdquo Metal Mine vol 41 no 3 pp 37ndash412012 in Chinese
[9] H Wang B Xia Y Lu T Gong and R Zhang ldquoStudy on thepropagation laws of hydrofractures meeting a faulted struc-ture in the coal seamrdquo Energies vol 10 no 5 pp 654ndash6722017
[10] J Xie J Xu and FWang ldquoMining-induced stress distributionof the working face in a kilometer-deep coal mine-a case studyin Tangshan coal minerdquo Journal of Geophysics and Engi-neering vol 15 no 5 pp 2060ndash2070 2018
[11] S Zhang X Wang G Fan D Zhang and C Jianbin ldquoPillarsize optimization design of isolated island panel gob-sideentry driving in deep inclined coal seam-case study ofPingmei No 6 coal seamrdquo Journal of Geophysics and Engi-neering vol 15 no 3 pp 816ndash828 2018
[12] Y Yuan S Tu F Wang X Zhang and B Li ldquoHydraulicsupport instability mechanism and its control in a fully-mechanized steep coal seam working face with large miningheightrdquo Journal of the Southern African Institute of Miningand Metallurgy vol 115 no 5 pp 441ndash447 2015
[13] J Sun L Wang and G Zhao ldquoFailure characteristics andconfined permeability of an inclined coal seam floor in fluid-solid couplingrdquo Advances in Civil Engineering vol 2018Article ID 2356390 12 pages 2018
[14] S Gu B Jiang G Wang H Dai and M Zhang ldquoOccurrencemechanism of roof-fall accidents in large-section coal seamroadways and related support design for Bayangaole coalmine Chinardquo Advances in Civil Engineering vol 2018 ArticleID 6831731 17 pages 2018
[15] H Xie M Gao R Zhang G Peng W Wang and A LildquoStudy on the mechanical properties andmechanical response
Advances in Civil Engineering 13
of coal mining at 1000m or deeperrdquo RockMechanics and RockEngineering vol 52 no 5 pp 1475ndash1490 2019
[16] Y Fang C Xu G Cui and B Kenneally ldquoScale model test ofhighway tunnel construction underlying mined-out thin coalseamrdquo Tunnelling and Underground Space Technology vol 56pp 105ndash116 2016
[17] M C He ldquoPhysical modeling of an underground roadwayexcavation in geologically 45deg inclined rock using infraredthermographyrdquo Engineering Geology vol 121 no 3-4pp 165ndash176 2011
[18] W Gong Y Peng M He and J Wang ldquoermal image andspectral characterization of roadway failure process in geo-logically 45deg inclined rocksrdquo Tunnelling and UndergroundSpace Technology vol 49 pp 156ndash173 2015
[19] H Yang S Cao Y Li C Sun and P Guo ldquoSoft roof failuremechanism and supporting method for gob-side entryretainingrdquo Minerals vol 5 no 4 pp 707ndash722 2015
[20] L Q Ma Y Zhang D S Zhang X Q Cao Q Q Li andY B Zhang ldquoSupport stability mechanism in a coal face withlarge angles in both strike and diprdquo Journal of the SouthernAfrican Institute of Mining and Metallurgy vol 115 no 7pp 599ndash606 2015
[21] M Jawed and R K Sinha ldquoDesign of rhombus coal pillars andsupport for roadway stability and mechanizing loading of facecoal using SDLs in a steeply inclined thin coal seammdashatechnical feasibility studyrdquo Arabian Journal of Geosciencesvol 11 no 15 pp 415ndash429 2018
[22] Y Yin J Zou Y Zhang Y Qiu and K Fang ldquoExperimentalstudy of the movement of backfilling gangues for goaf insteeply inclined coal seamsrdquo Arabian Journal of Geosciencesvol 11 no 12 pp 318ndash326 2018
[23] L Q Zhu and Y Zhang ldquoAnalysis of spontaneous com-bustion ldquothree zonesrdquo in 3237 working face of zhaogezhuangminerdquo Applied Mechanics and Materials vol 71ndash78pp 1978ndash1982 2011
[24] S Q He D Z Song Z L Li et al ldquoPrecursor of spatio-temporal evolution law of MS and AE activities for rock burstwarning in steeply inclined and extremely thick coal seamsunder caving mining conditionsrdquo Rock Mechanics and RockEngineering no 2 pp 1ndash21 2019
[25] H S Tu S H Tu Y Yuan F T Wang and Q S Bai ldquoPresentsituation of fully mechanized mining technology for steeplyinclined coal seams in Chinardquo Arabian Journal of Geosciencesvol 8 no 7 pp 1978ndash1982 2015
[26] W Lv Y Wu L Ming and J Yin ldquoMigration law of the roofof a composited backfilling longwall face in a steeply dippingcoal seamrdquo Minerals vol 9 no 3 pp 188ndash203 2019
[27] Z Bei S G Cao L G Wang and Y L Lu ldquoDeformationfailure mechanism and support measurements in roadway ofsteeply inclined coal seamrdquo Journal of Mining amp Safety En-gineering vol 28 no 2 pp 214ndash219 2011
[28] M Z Gao and H Q Jing ldquoMechanical analysis of asymmetricfloor heave of roadwayrdquo Journal of Anhui University of Scienceand Technology vol 32 no 4 pp 38ndash43 2012 in Chinese
[29] J G Liu A Y Cao Z M Yu G C Jing and H Y Liu ldquoStudyon stress characteristics of roadwayrsquos sides in deep and in-clined seamrdquo China Coal vol 42 no 8 pp 30ndash34 2016 inChinese
[30] X H Qi ldquoStudy on deformation characters and supportparameters of large angle seam roadway rock aroundrdquo Dis-sertation Xirsquoan University of Science and Technology XirsquoanChina 2015 in chinese
14 Advances in Civil Engineering
and the stress on the right wall of the floor (F-low side) isgreater than that on the left wall of the floor (F-high side)
From the laboratory model test results it can be seen thatthe stress distribution law of the right-angled trapezoidalroadway in a gently inclined seam is similar to the numericalsimulation and the stress distribution of the surroundingrock in the roof the two walls the floor and the corner of theroadway shows clear asymmetric characteristics howeverthere are some differences in the numerical valuese mainreason is that the proportion of similar materials size of themodel loading mode and so on have an impact on the testresults
6 Comparison and Analysis ofSimulation Results
It can be seen from the simulation results that the asym-metric distribution law of the surrounding rock in inclinedright angle trapezoidal roadway is basically the same as thatof large dip angle and steep inclined coal seam roadway butthe degree of stress asymmetry in the inclined coal seam ismuch lower than that of large dip angle coal seam enumerical simulation results of the asymmetric deformationand failure characteristics of the inclined trapezoidal
roadway in the inclined coal seam are consistent with thelaboratory model test (Figure 16) and the site failuremorphology of the Shitanjing No 2 mine (Figure 17) inwhich the deformation and failure law exhibits an asym-metrical feature Further the two walls of the roadway areseverely bulging and the low side is larger than the high side
7 Conclusion
Based on the theory of asymmetric stress distribution in thesurrounding rock of right-angled trapezoidal roadway in aninclined coal seam and considering the Shijiajing No 2mining area as the engineering background this paperfurther analyzes the asymmetric distribution characteristicsof the surrounding rock by using the FLAC3D finite dif-ference method rough verifications with a simulationtest the following conclusions were drawn
(1) e stress distribution of the surrounding rock of theright-angled trapezoidal roadway in the inclined coalseam shows clear asymmetryemain performanceis that the peak value of stress concentration in thelow side is greater than that in the high side and thedistance between the high side and the side wall ofthe roadway is greater than that in the low side With
(a) (b)
Figure 16 Deformation and failure of roadway in laboratory model test (a) 24deg (b) 27deg
(a) (b)
Figure 17 Deformation and failure of roadway in Shitanjing No 2 mine (a) 24deg (b) 27deg
12 Advances in Civil Engineering
the increase in the inclination angle and groundstress the difference between the peak value of stressconcentration and the distance from the side wall ofthe roadway is more obvious When the inclinationangle is 18degndash27deg the peak value of stress concen-tration of the low side is 107ndash133 times that of thehigh side and the distance from the high side to theside wall of the roadway is 126ndash379m larger thanthat of the low side Second two sharp corners thatare symmetric with the same inclination angle of thecoal seam show obvious compressive stress regionswhile the opposite two sharp corners show obvioustensile stress regions e maximum values ofcompressive and tensile stresses appear on the roof ofthe roadway
(2) Under the action of asymmetric stress the defor-mation and failure of the roadway surrounding therock also presents asymmetric characteristics etwo walls of the roadway exhibit extrusion dislo-cation and serious deformation and damage how-ever the deformation damage of the low side isobviously larger than that at the high side e mainreason is that the difference in height between thetwo walls of the roadway leads to the uneven dis-tribution of stress
(3) e results of numerical simulation are basicallyconsistent with laboratory model test and field en-gineering However there are some differences in thedata obtained and the main reason is that the two areaffected by the selection of the simulation parame-ters ratio of similar materials size of the model andloading method
Data Availability
e data used to support the findings of this study are in-cluded within the article
Conflicts of Interest
e authors declare that they have no conflicts of interestregarding the publication of this paper
Acknowledgments
is study was financially supported by the National NaturalScience Foundation of China (51174159 and 59974019) theChina Postdoctoral Science Foundation (2015M572580)and the Scientific Research Plan Projects of EducationDepartment of Shanxi Province of China (15JK1471)
Supplementary Materials
eoretical analysis process of roof stress distribution ininclined coal seam roadway (Supplementary Materials)
References
[1] H C Li ldquoStudy on deformation and failure characteristicsand stability control of large dip angle thick compound roofroadwayrdquo Dissertation Taiyuan University of TechnologyTaiyuan China 2014
[2] e National Development and Reform Commission PeoplersquosRepublic of China Energy Development 11th Five-Year PlanBeijing China 2007 in Chinese
[3] K Yu L Zhou Q Cao and Z Li ldquoEvolutionary game re-search on symmetry of workersrsquo behavior in coal mine en-terprisesrdquo Symmetry vol 11 no 2 pp 156ndash168 2019
[4] L Si Z Wang R Xu C Tan X Liu and J Xu ldquoImageenhancement for surveillance video of coal mining face basedon single-scale retinex algorithm combined with bilateralfilteringrdquo Symmetry vol 9 no 6 pp 93ndash108 2017
[5] F L He M G Qian and C Y Liu Support System of Supportand Surrounding Rock for High Productivity and High Effi-ciency Working Face China Mining Industry Press XuzhouChina 1997 in Chinese
[6] S J Chen Y Wang Y Z Wu Z Wang and W J ZhangldquoCoal resources and development potential in northwestChinardquo Northwestern Geology vol 4 pp 40ndash56 2006 inChinese
[7] X M Sun and M C He ldquoNumerical simulation research oncoupling support theory of roadway within soft rock atdepthrdquo Journal of China University of Mining and Technologyvol 34 no 2 pp 166ndash169 2005 in Chinese
[8] S X Wei J H Song and H W Jing ldquoNumerical analysis ofstress in the surrounding rock of the dynamic pressure tunnelwith inclined seamsrdquo Metal Mine vol 41 no 3 pp 37ndash412012 in Chinese
[9] H Wang B Xia Y Lu T Gong and R Zhang ldquoStudy on thepropagation laws of hydrofractures meeting a faulted struc-ture in the coal seamrdquo Energies vol 10 no 5 pp 654ndash6722017
[10] J Xie J Xu and FWang ldquoMining-induced stress distributionof the working face in a kilometer-deep coal mine-a case studyin Tangshan coal minerdquo Journal of Geophysics and Engi-neering vol 15 no 5 pp 2060ndash2070 2018
[11] S Zhang X Wang G Fan D Zhang and C Jianbin ldquoPillarsize optimization design of isolated island panel gob-sideentry driving in deep inclined coal seam-case study ofPingmei No 6 coal seamrdquo Journal of Geophysics and Engi-neering vol 15 no 3 pp 816ndash828 2018
[12] Y Yuan S Tu F Wang X Zhang and B Li ldquoHydraulicsupport instability mechanism and its control in a fully-mechanized steep coal seam working face with large miningheightrdquo Journal of the Southern African Institute of Miningand Metallurgy vol 115 no 5 pp 441ndash447 2015
[13] J Sun L Wang and G Zhao ldquoFailure characteristics andconfined permeability of an inclined coal seam floor in fluid-solid couplingrdquo Advances in Civil Engineering vol 2018Article ID 2356390 12 pages 2018
[14] S Gu B Jiang G Wang H Dai and M Zhang ldquoOccurrencemechanism of roof-fall accidents in large-section coal seamroadways and related support design for Bayangaole coalmine Chinardquo Advances in Civil Engineering vol 2018 ArticleID 6831731 17 pages 2018
[15] H Xie M Gao R Zhang G Peng W Wang and A LildquoStudy on the mechanical properties andmechanical response
Advances in Civil Engineering 13
of coal mining at 1000m or deeperrdquo RockMechanics and RockEngineering vol 52 no 5 pp 1475ndash1490 2019
[16] Y Fang C Xu G Cui and B Kenneally ldquoScale model test ofhighway tunnel construction underlying mined-out thin coalseamrdquo Tunnelling and Underground Space Technology vol 56pp 105ndash116 2016
[17] M C He ldquoPhysical modeling of an underground roadwayexcavation in geologically 45deg inclined rock using infraredthermographyrdquo Engineering Geology vol 121 no 3-4pp 165ndash176 2011
[18] W Gong Y Peng M He and J Wang ldquoermal image andspectral characterization of roadway failure process in geo-logically 45deg inclined rocksrdquo Tunnelling and UndergroundSpace Technology vol 49 pp 156ndash173 2015
[19] H Yang S Cao Y Li C Sun and P Guo ldquoSoft roof failuremechanism and supporting method for gob-side entryretainingrdquo Minerals vol 5 no 4 pp 707ndash722 2015
[20] L Q Ma Y Zhang D S Zhang X Q Cao Q Q Li andY B Zhang ldquoSupport stability mechanism in a coal face withlarge angles in both strike and diprdquo Journal of the SouthernAfrican Institute of Mining and Metallurgy vol 115 no 7pp 599ndash606 2015
[21] M Jawed and R K Sinha ldquoDesign of rhombus coal pillars andsupport for roadway stability and mechanizing loading of facecoal using SDLs in a steeply inclined thin coal seammdashatechnical feasibility studyrdquo Arabian Journal of Geosciencesvol 11 no 15 pp 415ndash429 2018
[22] Y Yin J Zou Y Zhang Y Qiu and K Fang ldquoExperimentalstudy of the movement of backfilling gangues for goaf insteeply inclined coal seamsrdquo Arabian Journal of Geosciencesvol 11 no 12 pp 318ndash326 2018
[23] L Q Zhu and Y Zhang ldquoAnalysis of spontaneous com-bustion ldquothree zonesrdquo in 3237 working face of zhaogezhuangminerdquo Applied Mechanics and Materials vol 71ndash78pp 1978ndash1982 2011
[24] S Q He D Z Song Z L Li et al ldquoPrecursor of spatio-temporal evolution law of MS and AE activities for rock burstwarning in steeply inclined and extremely thick coal seamsunder caving mining conditionsrdquo Rock Mechanics and RockEngineering no 2 pp 1ndash21 2019
[25] H S Tu S H Tu Y Yuan F T Wang and Q S Bai ldquoPresentsituation of fully mechanized mining technology for steeplyinclined coal seams in Chinardquo Arabian Journal of Geosciencesvol 8 no 7 pp 1978ndash1982 2015
[26] W Lv Y Wu L Ming and J Yin ldquoMigration law of the roofof a composited backfilling longwall face in a steeply dippingcoal seamrdquo Minerals vol 9 no 3 pp 188ndash203 2019
[27] Z Bei S G Cao L G Wang and Y L Lu ldquoDeformationfailure mechanism and support measurements in roadway ofsteeply inclined coal seamrdquo Journal of Mining amp Safety En-gineering vol 28 no 2 pp 214ndash219 2011
[28] M Z Gao and H Q Jing ldquoMechanical analysis of asymmetricfloor heave of roadwayrdquo Journal of Anhui University of Scienceand Technology vol 32 no 4 pp 38ndash43 2012 in Chinese
[29] J G Liu A Y Cao Z M Yu G C Jing and H Y Liu ldquoStudyon stress characteristics of roadwayrsquos sides in deep and in-clined seamrdquo China Coal vol 42 no 8 pp 30ndash34 2016 inChinese
[30] X H Qi ldquoStudy on deformation characters and supportparameters of large angle seam roadway rock aroundrdquo Dis-sertation Xirsquoan University of Science and Technology XirsquoanChina 2015 in chinese
14 Advances in Civil Engineering
the increase in the inclination angle and groundstress the difference between the peak value of stressconcentration and the distance from the side wall ofthe roadway is more obvious When the inclinationangle is 18degndash27deg the peak value of stress concen-tration of the low side is 107ndash133 times that of thehigh side and the distance from the high side to theside wall of the roadway is 126ndash379m larger thanthat of the low side Second two sharp corners thatare symmetric with the same inclination angle of thecoal seam show obvious compressive stress regionswhile the opposite two sharp corners show obvioustensile stress regions e maximum values ofcompressive and tensile stresses appear on the roof ofthe roadway
(2) Under the action of asymmetric stress the defor-mation and failure of the roadway surrounding therock also presents asymmetric characteristics etwo walls of the roadway exhibit extrusion dislo-cation and serious deformation and damage how-ever the deformation damage of the low side isobviously larger than that at the high side e mainreason is that the difference in height between thetwo walls of the roadway leads to the uneven dis-tribution of stress
(3) e results of numerical simulation are basicallyconsistent with laboratory model test and field en-gineering However there are some differences in thedata obtained and the main reason is that the two areaffected by the selection of the simulation parame-ters ratio of similar materials size of the model andloading method
Data Availability
e data used to support the findings of this study are in-cluded within the article
Conflicts of Interest
e authors declare that they have no conflicts of interestregarding the publication of this paper
Acknowledgments
is study was financially supported by the National NaturalScience Foundation of China (51174159 and 59974019) theChina Postdoctoral Science Foundation (2015M572580)and the Scientific Research Plan Projects of EducationDepartment of Shanxi Province of China (15JK1471)
Supplementary Materials
eoretical analysis process of roof stress distribution ininclined coal seam roadway (Supplementary Materials)
References
[1] H C Li ldquoStudy on deformation and failure characteristicsand stability control of large dip angle thick compound roofroadwayrdquo Dissertation Taiyuan University of TechnologyTaiyuan China 2014
[2] e National Development and Reform Commission PeoplersquosRepublic of China Energy Development 11th Five-Year PlanBeijing China 2007 in Chinese
[3] K Yu L Zhou Q Cao and Z Li ldquoEvolutionary game re-search on symmetry of workersrsquo behavior in coal mine en-terprisesrdquo Symmetry vol 11 no 2 pp 156ndash168 2019
[4] L Si Z Wang R Xu C Tan X Liu and J Xu ldquoImageenhancement for surveillance video of coal mining face basedon single-scale retinex algorithm combined with bilateralfilteringrdquo Symmetry vol 9 no 6 pp 93ndash108 2017
[5] F L He M G Qian and C Y Liu Support System of Supportand Surrounding Rock for High Productivity and High Effi-ciency Working Face China Mining Industry Press XuzhouChina 1997 in Chinese
[6] S J Chen Y Wang Y Z Wu Z Wang and W J ZhangldquoCoal resources and development potential in northwestChinardquo Northwestern Geology vol 4 pp 40ndash56 2006 inChinese
[7] X M Sun and M C He ldquoNumerical simulation research oncoupling support theory of roadway within soft rock atdepthrdquo Journal of China University of Mining and Technologyvol 34 no 2 pp 166ndash169 2005 in Chinese
[8] S X Wei J H Song and H W Jing ldquoNumerical analysis ofstress in the surrounding rock of the dynamic pressure tunnelwith inclined seamsrdquo Metal Mine vol 41 no 3 pp 37ndash412012 in Chinese
[9] H Wang B Xia Y Lu T Gong and R Zhang ldquoStudy on thepropagation laws of hydrofractures meeting a faulted struc-ture in the coal seamrdquo Energies vol 10 no 5 pp 654ndash6722017
[10] J Xie J Xu and FWang ldquoMining-induced stress distributionof the working face in a kilometer-deep coal mine-a case studyin Tangshan coal minerdquo Journal of Geophysics and Engi-neering vol 15 no 5 pp 2060ndash2070 2018
[11] S Zhang X Wang G Fan D Zhang and C Jianbin ldquoPillarsize optimization design of isolated island panel gob-sideentry driving in deep inclined coal seam-case study ofPingmei No 6 coal seamrdquo Journal of Geophysics and Engi-neering vol 15 no 3 pp 816ndash828 2018
[12] Y Yuan S Tu F Wang X Zhang and B Li ldquoHydraulicsupport instability mechanism and its control in a fully-mechanized steep coal seam working face with large miningheightrdquo Journal of the Southern African Institute of Miningand Metallurgy vol 115 no 5 pp 441ndash447 2015
[13] J Sun L Wang and G Zhao ldquoFailure characteristics andconfined permeability of an inclined coal seam floor in fluid-solid couplingrdquo Advances in Civil Engineering vol 2018Article ID 2356390 12 pages 2018
[14] S Gu B Jiang G Wang H Dai and M Zhang ldquoOccurrencemechanism of roof-fall accidents in large-section coal seamroadways and related support design for Bayangaole coalmine Chinardquo Advances in Civil Engineering vol 2018 ArticleID 6831731 17 pages 2018
[15] H Xie M Gao R Zhang G Peng W Wang and A LildquoStudy on the mechanical properties andmechanical response
Advances in Civil Engineering 13
of coal mining at 1000m or deeperrdquo RockMechanics and RockEngineering vol 52 no 5 pp 1475ndash1490 2019
[16] Y Fang C Xu G Cui and B Kenneally ldquoScale model test ofhighway tunnel construction underlying mined-out thin coalseamrdquo Tunnelling and Underground Space Technology vol 56pp 105ndash116 2016
[17] M C He ldquoPhysical modeling of an underground roadwayexcavation in geologically 45deg inclined rock using infraredthermographyrdquo Engineering Geology vol 121 no 3-4pp 165ndash176 2011
[18] W Gong Y Peng M He and J Wang ldquoermal image andspectral characterization of roadway failure process in geo-logically 45deg inclined rocksrdquo Tunnelling and UndergroundSpace Technology vol 49 pp 156ndash173 2015
[19] H Yang S Cao Y Li C Sun and P Guo ldquoSoft roof failuremechanism and supporting method for gob-side entryretainingrdquo Minerals vol 5 no 4 pp 707ndash722 2015
[20] L Q Ma Y Zhang D S Zhang X Q Cao Q Q Li andY B Zhang ldquoSupport stability mechanism in a coal face withlarge angles in both strike and diprdquo Journal of the SouthernAfrican Institute of Mining and Metallurgy vol 115 no 7pp 599ndash606 2015
[21] M Jawed and R K Sinha ldquoDesign of rhombus coal pillars andsupport for roadway stability and mechanizing loading of facecoal using SDLs in a steeply inclined thin coal seammdashatechnical feasibility studyrdquo Arabian Journal of Geosciencesvol 11 no 15 pp 415ndash429 2018
[22] Y Yin J Zou Y Zhang Y Qiu and K Fang ldquoExperimentalstudy of the movement of backfilling gangues for goaf insteeply inclined coal seamsrdquo Arabian Journal of Geosciencesvol 11 no 12 pp 318ndash326 2018
[23] L Q Zhu and Y Zhang ldquoAnalysis of spontaneous com-bustion ldquothree zonesrdquo in 3237 working face of zhaogezhuangminerdquo Applied Mechanics and Materials vol 71ndash78pp 1978ndash1982 2011
[24] S Q He D Z Song Z L Li et al ldquoPrecursor of spatio-temporal evolution law of MS and AE activities for rock burstwarning in steeply inclined and extremely thick coal seamsunder caving mining conditionsrdquo Rock Mechanics and RockEngineering no 2 pp 1ndash21 2019
[25] H S Tu S H Tu Y Yuan F T Wang and Q S Bai ldquoPresentsituation of fully mechanized mining technology for steeplyinclined coal seams in Chinardquo Arabian Journal of Geosciencesvol 8 no 7 pp 1978ndash1982 2015
[26] W Lv Y Wu L Ming and J Yin ldquoMigration law of the roofof a composited backfilling longwall face in a steeply dippingcoal seamrdquo Minerals vol 9 no 3 pp 188ndash203 2019
[27] Z Bei S G Cao L G Wang and Y L Lu ldquoDeformationfailure mechanism and support measurements in roadway ofsteeply inclined coal seamrdquo Journal of Mining amp Safety En-gineering vol 28 no 2 pp 214ndash219 2011
[28] M Z Gao and H Q Jing ldquoMechanical analysis of asymmetricfloor heave of roadwayrdquo Journal of Anhui University of Scienceand Technology vol 32 no 4 pp 38ndash43 2012 in Chinese
[29] J G Liu A Y Cao Z M Yu G C Jing and H Y Liu ldquoStudyon stress characteristics of roadwayrsquos sides in deep and in-clined seamrdquo China Coal vol 42 no 8 pp 30ndash34 2016 inChinese
[30] X H Qi ldquoStudy on deformation characters and supportparameters of large angle seam roadway rock aroundrdquo Dis-sertation Xirsquoan University of Science and Technology XirsquoanChina 2015 in chinese
14 Advances in Civil Engineering
of coal mining at 1000m or deeperrdquo RockMechanics and RockEngineering vol 52 no 5 pp 1475ndash1490 2019
[16] Y Fang C Xu G Cui and B Kenneally ldquoScale model test ofhighway tunnel construction underlying mined-out thin coalseamrdquo Tunnelling and Underground Space Technology vol 56pp 105ndash116 2016
[17] M C He ldquoPhysical modeling of an underground roadwayexcavation in geologically 45deg inclined rock using infraredthermographyrdquo Engineering Geology vol 121 no 3-4pp 165ndash176 2011
[18] W Gong Y Peng M He and J Wang ldquoermal image andspectral characterization of roadway failure process in geo-logically 45deg inclined rocksrdquo Tunnelling and UndergroundSpace Technology vol 49 pp 156ndash173 2015
[19] H Yang S Cao Y Li C Sun and P Guo ldquoSoft roof failuremechanism and supporting method for gob-side entryretainingrdquo Minerals vol 5 no 4 pp 707ndash722 2015
[20] L Q Ma Y Zhang D S Zhang X Q Cao Q Q Li andY B Zhang ldquoSupport stability mechanism in a coal face withlarge angles in both strike and diprdquo Journal of the SouthernAfrican Institute of Mining and Metallurgy vol 115 no 7pp 599ndash606 2015
[21] M Jawed and R K Sinha ldquoDesign of rhombus coal pillars andsupport for roadway stability and mechanizing loading of facecoal using SDLs in a steeply inclined thin coal seammdashatechnical feasibility studyrdquo Arabian Journal of Geosciencesvol 11 no 15 pp 415ndash429 2018
[22] Y Yin J Zou Y Zhang Y Qiu and K Fang ldquoExperimentalstudy of the movement of backfilling gangues for goaf insteeply inclined coal seamsrdquo Arabian Journal of Geosciencesvol 11 no 12 pp 318ndash326 2018
[23] L Q Zhu and Y Zhang ldquoAnalysis of spontaneous com-bustion ldquothree zonesrdquo in 3237 working face of zhaogezhuangminerdquo Applied Mechanics and Materials vol 71ndash78pp 1978ndash1982 2011
[24] S Q He D Z Song Z L Li et al ldquoPrecursor of spatio-temporal evolution law of MS and AE activities for rock burstwarning in steeply inclined and extremely thick coal seamsunder caving mining conditionsrdquo Rock Mechanics and RockEngineering no 2 pp 1ndash21 2019
[25] H S Tu S H Tu Y Yuan F T Wang and Q S Bai ldquoPresentsituation of fully mechanized mining technology for steeplyinclined coal seams in Chinardquo Arabian Journal of Geosciencesvol 8 no 7 pp 1978ndash1982 2015
[26] W Lv Y Wu L Ming and J Yin ldquoMigration law of the roofof a composited backfilling longwall face in a steeply dippingcoal seamrdquo Minerals vol 9 no 3 pp 188ndash203 2019
[27] Z Bei S G Cao L G Wang and Y L Lu ldquoDeformationfailure mechanism and support measurements in roadway ofsteeply inclined coal seamrdquo Journal of Mining amp Safety En-gineering vol 28 no 2 pp 214ndash219 2011
[28] M Z Gao and H Q Jing ldquoMechanical analysis of asymmetricfloor heave of roadwayrdquo Journal of Anhui University of Scienceand Technology vol 32 no 4 pp 38ndash43 2012 in Chinese
[29] J G Liu A Y Cao Z M Yu G C Jing and H Y Liu ldquoStudyon stress characteristics of roadwayrsquos sides in deep and in-clined seamrdquo China Coal vol 42 no 8 pp 30ndash34 2016 inChinese
[30] X H Qi ldquoStudy on deformation characters and supportparameters of large angle seam roadway rock aroundrdquo Dis-sertation Xirsquoan University of Science and Technology XirsquoanChina 2015 in chinese
14 Advances in Civil Engineering
![Vibration-BasedDamageDetectionofaSteel ...downloads.hindawi.com/journals/ace/2020/8889277.pdfdefinedamageprobabilityfunctions[2].Wheninvisible damageoccursonacomplicatedstructuresuchasacom-positebridgedeckwithshearconnectors,theVBDDmethod](https://img.pdfslide.net/doc/110x75/5ff13eadf9bc627e1225d39a/vibration-baseddamagedetectionofasteel-deinedamageprobabilityfunctions2wheninvisible.jpg)
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![CostIndexPredictionsforConstructionEngineeringBasedon ...downloads.hindawi.com/journals/ace/2020/6518147.pdfareonlysuitableforshort-termpredictions[11],andthe multivariatetimeseriesmethodsarecostlyintermsoftheir](https://img.pdfslide.net/doc/110x75/608d3464e20410064c6c71e7/costindexpredictionsforconstructionengineeringbasedon-areonlysuitableforshort-termpredictions11andthe.jpg)
