Blasting-InducedVibrationResponseoftheTransitionSectionin

Research ArticleBlasting-Induced Vibration Response of the Transition Section ina Branching-Out Tunnel and Vibration Control Measures

Feng Cao1 Sheng Zhang 23 and Tonghua Ling4

1Hunan Provincial Communications Planning Survey and Design Institute Company Limited Changsha 410200 China2School of Civil Engineering Hunan City University Yiyang 413000 China3Department of Mechanical Engineering University of Houston Houston 77204 USA4School of Civil Engineering Changsha University of Science amp Technology Changsha 410114 China

Correspondence should be addressed to Sheng Zhang zhangsheng0403311163com

Received 20 February 2020 Revised 2 June 2020 Accepted 4 July 2020 Published 28 July 2020

Academic Editor Emanuele Brunesi

Copyright copy 2020 Feng Cao et al )is 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

Blasting-induced vibration during the excavation of transition section in a branching-out tunnel causes damage and hence affectsthe safety and stability of the supporting structure and surrounding rock To examine the effects of excavation and blasting of thetransition section in the posterior tunnel on the supporting structures of the anterior tunnel the influences of the blasting-inducedvibration in the posterior tunnel on the anterior tunnel were analyzed under different surrounding rock levels excavationtechniques distances from explosive source and net spans )is method was performed by combining numerical simulation withblasting-induced vibration monitoring according to the construction characteristics of the transition section in a branching-outtunnel of a highway A control technique was investigated to assure the safety and stability of the anterior tunnel during theexcavation and blasting of the posterior tunnel Results demonstrate that (1) the vibration velocity peak behind the blastingexcavation surface of the tunnel is higher than that in front )ese results suggest paying much attention in monitoring vibrationvelocity within 10m behind the excavation surface (2) )e blasting-induced vibration velocity peak on the spandrel at the sidethat faces the blasting in the anterior tunnel is 20ndash25 times than that at the side behind the blasting Moreover the blasting-induced vibration velocity peak on the haunch at the side that faces the blasting in the anterior tunnel is 6-7 times than that at theside behind the blasting (3) Instead of the full-face excavation method the use of center cross diagram (CRD) technique or sidewall pilot tunnel method is suggested for the excavation of surrounding rocks of IV-level V-level and III-level with a net spansmaller than 3m (4) Vibration control measures such as double wedge-shaped cut blasting and floor blast-hole staged det-onation were adopted by designing and optimizing blasting parameters (eg total explosives maximal segment explosivequantity detonation order and detonation interval) in posterior tunnel According to the test the blasting-induced vibrationvelocity peak which is monitored in the anterior tunnel can be controlled within 10 cms to assure the safety and stability of thesupporting structure and surrounding rocks of the tunnel

1 Introduction

Branching-out tunnel as a novel structural form attractsincreasing attention with the continuous development ofhigh-level highway planning and construction in recentyears and the limitations that are due to considerations ofland resource utilization and low engineering cost caused bythe terrain and construction site [1ndash3] )e branching-outtunnel is composed of three parts namely the large-spanmultiarch and small net span sections )e branching-out

tunnel has promising application prospects in difficulthighway construction and in transition project of bridgesand tunnels because it exhibits the engineering character-istics of large-span multiarch tunnel and neighborhoodtunnel [4ndash6] However the distance between the two holeschanges continuously and the stress structures in thetransition section become complicated because the blastingexcavation of the posterior tunnel in the transition section ofthe branching-out tunnel can influence the stability of thesupporting structure of the anterior tunnel thereby further

HindawiAdvances in Civil EngineeringVolume 2020 Article ID 6149452 11 pageshttpsdoiorg10115520206149452

changing the stress state and mechanical behavior of thesupporting structure in the tunnel and even local collapse oroverall instability of the supporting structure [7 8] )esefactors cause certain restraints against efficiency of con-struction and the engineering quality of the tunnel)erefore studying the influences of posterior tunnelconstruction on the stability of the anterior tunnel in thetransition section of branching-out tunnel has importantpractical significance [9 10]

With respect to the selection of tunnel constructionschemes the drilling and blasting method is a practicaltechnique for underground projects in traffic tunnel mu-nicipal-service tunnel hydraulic tunnel and mine tunnelbecause of its lower operation cost stronger adaptation andsimpler construction technique compared with tunnelboring machine and shield driving methods [11ndash13] Nev-ertheless partial energies generated by blast-hole explosionare used to break rocks whereas the highest energy istransformed into blast stress and seismic waves to prop-agate and connect microdefects on supporting structuresand rockmasses thereby decreasing the bearing capacities ofthe supporting structures and rock masses [14ndash16] Abun-dant field tests and numerical simulation studies on thepropagation of blasting-induced vibration in tunnel and itsinfluences on supporting structures and rock masses havebeen conducted to minimize blasting-related damage to thesupporting structures and rock masses [17ndash19] Howeverstudies on the attenuation laws of blasting-induced vibrationin a branching-out tunnel are limited In fact the transitionsection has become the key part in the blasting excavation ofa branching-out tunnel because of the great changes inchamber shapes and supporting structural forms in thetransition section of a branching-out tunnel )ereforeperforming numerical simulation and field monitoring teston blasting-induced vibration response features of thetransition section of a branching-out tunnel is crucial

)is study combined the engineering characteristics oftransition section of a branching-out tunnel to optimize thedesign of the tunnel blasting scheme and verified and an-alyzed the blasting scheme by using the measurement data ofblasting-induced vibration Subsequently the blasting-in-duced vibration response features of the transition section ofa branching-out tunnel under different buried depthssurrounding rock levels excavation technique shared rockthicknesses and net spans were carried out by using a finiteelement numerical simulation analysis Finally someblasting-induced vibration control measures were proposed)is study realized safety and stability during the controlledblasting construction of the transition section of abranching-out tunnel

2 Project Overview

A highway tunnel adopts the branching-out tunnel and islocated in karst middle and low mountainous areas A greattopographic relief along the highway is observed and theground elevation ranges between 42706 and 64027m )emaximum buried depth is 185m )e branching-out sec-tion of the tunnel is 1385m long and is divided into three

sections namely large-span multiarch and small net spansections )e plan view of the branching-out tunnel isshown in Figure 1 and the profile view of 1ndash1 is shown inFigure 2 )e tunnel transition section is located 20m infront and rear of the interface between the sandwichmultiarch tunnel and the neighborhood tunnel )echaracteristics of the transition section of the branching-out tunnel are mainly manifested as the constantlychanging width of the sandwich wall the abrupt cross-sectional shape of the transition section and the stressconcentration From the geological situation the sur-rounding rock of the tunnel is composed of slightlyweathered limestone with developed dissolution fissuresand relatively broken rock masses )e minimum net spanbetween two adjacent tunnels is 1m and the minimumburied depth is only 3m )e short net span small burieddepth complicated structural stresses and soft sur-rounding rocks in the tunnel bring extremely difficulties toblasting excavation

3 Design and Verification ofBlasting Parameters

31 Design of Tunnel Blasting Parameters According torelevant rules in Safety Regulations for Blasting (GB6722-2014) the critical value of safe particle vibration velocity is10ndash20 cms [20ndash22] Considering the structural uniquenessof the transition section in a branching-out tunnel the safetycritical value of blasting-induced vibration velocity wasdetermined as 10 cms In the blasting design the net span ofthe transition section was 2-3m )e buried depth andsurrounding rock level were set 25-35m and V-level re-spectively )e CRD method was applied to excavate rockmass )e CRD method in the posterior tunnel and blast-hole layout in the upper bench left Zone I are shown inFigure 3

Given that the vibration caused by cut-hole explosion onno-free face is the maximum the blasting parameters in theupper bench left Zone I of the posterior tunnel were going tobe optimized )e optimized blasting design parameters areshown in Table 1 and the blast-hole layout is shown inFigure 3 Double wedge-shaped cut blasting was applied todecrease single cut-hole blasting-induced vibration Super-position of blasting-induced vibration waves is avoided andthe blasting-induced vibration velocity is decreased byshortening the footage driving cycle decreasing maximalsegment explosive quantity and setting skip detonators toextend the interval time

32 Verification Analysis of Blasting-Induced Vibration DataBlasting-induced vibration in the anterior tunnel will bemonitored to investigate the influences of posterior tunnelblasting on the vibration of the anterior tunnel Blasting-induced vibration monitoring points on the section of theanterior tunnel were mainly set at the spandrel haunch andarch foot on the side facing with detonation Monitoringpoints were set symmetrically on the advancing andretreating directions around the axial line along the

2 Advances in Civil Engineering

explosive excavation surface )e space between twomonitoring points was set as 5m and five sections wereinvolved )ree monitoring points were set on each sectionthus setting 15 monitoring points )e specific layouts ofmonitoring points are shown in Figure 4

Blasting-induced vibration was monitored by using aTC-4850 intelligent vibration monitor )e TC-4850 intel-ligent vibration monitor had a triaxial vibration velocitysensor A statistical analysis on monitoring results at dif-ferent points on haunch spandrel and arch foot of the side

facing with detonation was carried out Results are shown inTable 2

Table 2 shows that radial vibration velocities at allmonitoring points are higher than the tangential and verticalvibration velocities)e blasting-induced vibration velocity atthe spandrel is higher than those at the haunch and arch footand the maximum vibration velocity peak is at the 3spandrel which amounts to 836 cms or is smaller than thecritical value of safe particle vibration velocity (10 cms) )isresult reflects that the blasting-induced vibration is controlled

1

1

Neighborhood tunnel

Hig

hway

subg

rade

Shared rock

10 405 88

Neighborhood tunnelLarg

e-sp

an tu

nnel

Multiarchtunnel

Multiarchtunnel

Driving direction

Driving direction

Sandwich wall

Transition section (40m)

Interface

Figure 1 Plan view of the transition section of the branching-out tunnel (unit m)

1224

Posterior tunnel

1224100~600

Anterior tunnel996

Figure 2 Profile view of 1ndash1 (unit cm)

I

V

IV

VI

II

III

(a)

97150

100

621513

119

7

5

5

17

3 31 1 5

7

I

(b)

Figure 3 (a) CRD method and (b) blast-hole layout (unit mm) in the posterior tunnel

Advances in Civil Engineering 3

4 Numerical Verification

41 Introduction of LS-DYAN LS-DYAN is finite elementnumerical calculation software for geometrical nonlinearityand material nonlinearity It is suitable for analyzingstructural nonlinear impact dynamic problems such asexplosions and structural collisions Lagrange is the mainalgorithm used and ALE and Euler algorithms are alsoincluded )e main functions of the LS-DYAN program areto display solutions and structural analysis It also containsdifferent element libraries including thin and thick shellelements beam elements and other two-dimensional andthree-dimensional solid elements Various types of elementscan use multiple algorithms )ey also have large straindisplacement and rotation performance which canmeet theneeds of finite element meshing of various solid structures

)e explicit dynamic analysis of ANSYSLS-DYNA in-cludes three basic operations namely preprocessing solv-ing and postprocessing In the preprocessing stage thisarticle mainly uses ANSYSLS-DYNA software )e work-flow can be described as follows specify the element typeestablish a geometric model divide the mesh form a finiteelement model define the contact surface construction loadand boundary conditions and import the information intothe K file )en submit the K file to the LS-DYNA solver forresult Finally postprocessors POST1 and POST26 ofANSYS are used to visualize the calculation results

42 Calculation Model and Parameters Some research re-sults have demonstrated that the net width of the tunnel is anevaluation index of difficulties in vibration-controlled

Table 1 Optimized blasting design parameters

Sections Type of holes Hole depth(m)

Number ofholes Single-hole explosive quantity (kg) Maximal segment explosive quantity

(kg)1 Cut-hole 13 6 035 2103 Cut-hole 13 4 030 1205 Auxiliary hole 10 8 020 1607 Auxiliary hole 10 11 020 2209 Auxiliary hole 10 8 020 16011 Auxiliary hole 10 9 020 18013 Auxiliary hole 10 10 015 15015 Periphery hole 10 12 015 18017 Floor hole 12 11 025 275Total 79 1655

Explosive source

Posterior tunnel Monitoring points

Anterior tunnel

Sandwich wall

(a)

Excavation surface Surrounding rock

Sandwich wall Shared rockMonitoring points

55 5 532 4 51

(b)

Figure 4 Layouts of vibration velocity monitoring points (a) sectional layout (b) plane layout (unit m)


blasting excavation of the posterior tunnel [23 24] Giventhe small net width of the tunnel the blasting construction ofthe posterior tunnel can influence the stability of the sur-rounding rock and supporting structure in the anteriortunnel In this branching-out tunnel the transition sectionwith a net span of 1ndash6m is used as the analysis regionAccording to practical field situation a three-dimensionalmodel was constructed by using the ANSYSLS-DYNAexplicit finite element program to investigate the influencefeatures of blasting-induced vibration in posterior tunnel ofthe transition section on the supporting structures of theanterior tunnel

)is calculation applied the expanded boundary ranges toreduce the influences of boundary effects )e calculation sizeof the constructed model was both 75m at the left and rightboundaries )e upper boundary was extended to the surfaceand the lower boundary was set to 40m )e longitudinallength of the tunnel was 100m An X-directional displace-ment constraint was applied on the right and left sides of themodel and a Y-directional displacement constraint was ap-plied on the bottom of the model)e top of the model used afree boundary )e front and back surfaces of the modelapplied a Z-directional displacement constraint Nearly allpositions of the model were applied with nonreflectingboundaries except for the top surface of the model )eseboundary conditions can avoid the influences of stress wavereflection on the calculation results of the model

In this numerical calculation model the explosive cor-responds to a continuous coupled charge structure and is setat the center of the charge for detonating SOLID_164 el-ements are used for explosives rock and soil bodies andconcrete )e model is divided by a solid grid and dis-placement constraints and nonreflective boundary condi-tions are carried out on the infinite area and explosiveboundary surface that extends outside the rock body )efluid-solid coupling ALE algorithms are used between therock and soil bodies and the explosives and concrete For theexplosive ALE algorithm is used to control the rheology ofthe unit )e rock soil and pipeline are controlled by using

the Lagrange algorithm to solve the problem and to reducethe result error caused by the large deformation in thesolution calculation )e calculation model is shown inFigure 5 )e model adopts the hexahedral mapping griddivision unit with high unit order and the grid division has atotal of 213226 solid units and 221598 nodes

According to relevant literature review the vibrationstrength caused by blasting in cut-holes is stronger thanthose of auxiliary and surrounding holes during tunnelblasting [25 26] )is study focused on the dynamic analysisof blasting in cut-holes )e concentrated charging modedoes not affect the studies regarding the influencing laws ofvibration waves on the supporting structure of the tunnelFor the convenience of calculation the cut-hole was sim-ulated by using the concentrated charging mode and thecut-holes in the same section were simplified into a blastinghole which was at the low right position of the upper step onthe left of the posterior tunnel )e explosion process wassimulated by JonesndashWilkensndashLee (JWL) state equationPressure in the explosive unit after detonation was calculatedfrom the state equation and was expressed as

Peos A 1 minusω

R1V1113888 1113889e

minusR1V+ B 1 minus

ωR2V

1113888 1113889eminusR2V

+ωE0

V

(1)

where A B R1 R2 and ω are constants of the state equationV is the relative volume and E0 is the initial internal energydensity

Pressure in a unit is

P F times Peos (2)

where F is the combustion reaction rate of unitExplosive was simulated by the MAT_HIGH_EXPLO-

SIVE_BURN model )e state equation of the explosive wasdefined by EOS_JWL Parameters of the applied explosivematerials and state equation are shown in Table 3

According to field investigation the surrounding rocksin the tunnel include clay and weak weathered limestone

Table 2 Monitoring data of blasting-induced vibration at different points

Monitoringpoints

Position of monitoringpoints

Maximal segment explosivequantity (kg)

Distance from explosivesources (m)

Peak velocity (cms)Radial Tangential Vertical

1Haunch 275 172 161 145 144Spandrel 275 179 223 204 202Arch foot 275 186 091 096 102






with small thickness on the roof )e primary lining is C20shotcrete and the secondary lining is C25 concrete )ereinforcement area of rock bolts is estimated according tothe Dulacska formula [27]

c0prime c0 +πD2σs 12 + φ0180∘( 1113857sin 45∘ + φ02( 1113857

43

radicSaSc

(3)

where c0prime is the equivalent cohesion of rock bolts rein-forcement area kPa c0 is the initial cohesion of surroundingrock kPa φ0 is the initial internal friction angle of sur-rounding rock deg D is the diameter of rock bolts mm σs isthe tensile strength of rock bolts kPa Sa is the longitudinalspacing of rock bolts along the tunnel m Sc is the annularspacing of rock bolts m

)e strength of the steel arch is converted to concrete byan equivalent method and the following formula can bereferred to [28]

E E0 +SgEg

Ss

(4)

where E is the elastic modulus of shotcrete after conversionGPa E0 is the initial elastic modulus of shotcrete GPa Eg isthe elastic modulus of the steel arch GPa Ss is the equivalentreplacement cross-sectional area of shotcrete cm2 Sg is thecross-sectional area of steel arch cm2

Combined with field investigation and laboratory ex-periment the physical and mechanical parameters of thesurrounding rock and concrete are shown in Table 4

43 Calculation Conditions Many factors such as terraincondition geological condition charging structure deto-nation mode and distance from explosive sources can affectthe strength of blasting-induced vibration [29 30] )isstudy mainly selected vibration velocity peak as the analysisindex of blasting-induced vibration strength)e calculationconditions comprise the combination of the 3 levels of

surrounding rocks (III IV and V) 6 buried depths (5 1020 30 40 50 and 100m) 6 net spans (1 2 3 4 5 and 6m)and 9 different distances from explosive source (minus20 minus15minus10 minus5 0 5 10 15 and 20m) )e blasting-induced vi-bration velocity peaks under different calculation conditionswere calculated )e detonation mode of the right and leftholes was applied initially and after the simulation processrespectively )e effects of blasting-induced vibration on thetransition section of the branching-out tunnel under dif-ferent conditions were discussed and the blasting-inducedvibration propagation laws in the transition section wereanalyzed

44 Results Analysis

441 Effects of Buried Depth and Net Span It was hy-pothesized in calculation that the surrounding rocks wereIII-level and the bench cut method was applied )e vari-ation curves of blasting-induced vibration velocity peak withburied depth at different net spans in the anterior tunnel areshown in Figure 6

Figure 6 shows that the blasting-induced vibration ve-locity peak increases with the buried depth )e vibrationvelocity peak curve tends to be stable with the continuousincrease in buried depth )e vibration velocity peaks oftunnels with different net spans stabilize at different burieddepths )e higher the net span is the higher the burieddepth is when the vibration velocity peak stabilizes )isphenomenon can be explained as follows When the burieddepth is smaller than the net span the coverage layer on thetunnel roof is relatively thin and strong blasting-inducedvibrations are observed thereby weakening the vibrationvelocity in the anterior tunnel at the side facing the blastingWhen the buried depth is higher than the net span thecoverage layer on the tunnel roof is thickened gradually andthe vibration velocity in the anterior tunnel increases

150m

100m150m

40m

XY

Z

(a)

XY

Z

(b)

Figure 5 Calculation model and meshing (a) overall calculation model (b) tunnel lining model

Table 3 Parameters of explosive materials

Density (gcm3) Detonation velocity (ms) A (GPa) B (GPa) R1 R2 ω E0 (GPa)

11 4200 524times104 769 42 1 03 85


accordingly )erefore real-time monitoring over theblasting-induced vibration velocity in the anterior tunneland coverage layer adjusting and optimizing the blastingdesign parameters and applying surface grouting shotcreteand rock bolt support to the coverage layer on the roof oftunnel are suggested because the transition section of thebranching-out tunnel is generally located at the tunnel portalwhere the buried depth is small

442 Effects of Surrounding Rock Level and Net SpanTo analyze influences of surrounding rock level and net spanon the posterior tunnel three levels of surrounding rocks(eg III IV and V) were set and the bench cut method wasused )e buried depth and net span were set as 30m and1ndash6m respectively )e variation curves of the blasting-induced vibration velocity peak with net span under dif-ferent surrounding rock levels in the transition section arecalculated (Figure 7)

Figure 7 shows that the blasting-induced vibration ve-locity peak in hard and integral rockmass attenuates quickly)at is if rock masses are soft and broken then the blasting-induced vibration velocity peak attenuates slowly In view ofnet span the relationship between blasting-induced vibra-tion velocity peak and net span is nonlinear because ofseveral factors such as surrounding rock levels )e

vibration velocity peak decreases with the continuous in-crease in net spanWhen the net span is smaller than 3m theblasting-induced vibration velocity peak attenuates dra-matically When the net span is higher than 3m theblasting-induced vibration velocity peak tends to stabilize)erefore weak blasting under the assistance of mechanicalexcavation and timely support is recommended to thesection with V-level surrounding rocks net span smallerthan 3m and poor stability In other sections the appro-priate excavation mode shall be selected according topractical field situations and blasting-induced vibrationstrength such as bench cut method center cross diagram(CRD) or side drift method Moreover the blasting designscheme shall be monitored and perfected at a proper timeand blasting-induced vibration control measures shall beimplemented well

443 Effects of Excavation Methods and Net SpanFull-face excavation upper bench lower bench CRD andside drift methods were used in the calculation )e burieddepth surrounding rock level and net span of the tunnelwere set as 30m III-level and 1ndash6m respectively )evariation curves of the blasting-induced vibration velocitypeak with net span under different excavation methods areshown in Figure 8

Figure 8 shows that the CRD and side drift methodswhich decrease the rock mass volume and charge quantity

Table 4 Calculation parameters of surrounding rock and concrete

Materials Density(gcm3) Elasticity modulus (GPa) Poissonrsquos ratio Shear modulus (GPa) Compressive strength (GPa)

III-level surrounding rock 25 40 028 185 0058IV-level surrounding rock 22 20 032 165 0018V-level surrounding rock 18 5 037 105 0006C25 concrete 25 40 018 250 0145

Net span 1mNet span 2mNet span 3m


0

2

4

6

8

10

12

Vib

ratio

n ve

loci

ty p

eak

(cm

s)

2 3 10050106541 20Buried depth (m)

Figure 6 Variation curves of vibration velocity peak with burieddepth at different net spans

V-levelIV-levelIII-level

0

10

20

30

40

50

60

Vibr

atio

n ve

loci

ty p

eak

(cm

s)

72 3 4 5 610Net span (m)

Figure 7 Variation curves of vibration velocity peak with net spanunder different surrounding rock levels


for single-stage blasting and can reduce vibration signifi-cantly excavate pilot tunnel first Importantly the pilottunnel shall be far away from the anterior tunnel to reducevibrations According to the variation curve of the vibrationvelocity with net span the blasting-induced vibration ve-locity peak curve is relatively sharp when the net span issmaller than 3m indicating that the reduction rate is highWhen the net span is between 3 and 6m the curve is rel-atively gentle )erefore the use of CRD or side driftmethod which has many blasting-induced vibrations totunnels with net span smaller than 3m is recommended torelease blasting-induced vibration waves to surroundingrocks and thereby decrease the influences of maximal seg-ment explosive quantity on vibration of surrounding rocksWhen the net span is higher than 3m the application of thebench cut method is suggested )e full-face excavationmethod is not recommended because it generates excessiveblasting-induced vibration velocity

444 Effects of Shared Rock Suppose that the buried depthof tunnel is 30m and III-level surrounding rocks apply thebench cut method )e advancing directions of the tunnelwhich refer to the front surface of the excavation are 10mand 20m )e portal direction which refers to the surfacebehind the excavation is minus10m and minus20m Five explosivepoints were set at minus10 minus20 0 10 and 20m and werenumbered as explosive sources 1ndash5 respectively )e vari-ation curve of blasting-induced vibration velocity peak withdistance from the explosive source is shown in Figure 9

Figure 9 illustrates that the vibration velocity peak be-hind the explosive excavation surface at different explosivesource points is higher than that in front of the explosivesurface )e reason is related to the free face of the sharedrock behind the excavation surface At the blasting of theposterior tunnel the free face on the shared rock behind theexcavation surface can amplify the detonation wave thereby

causing the blasting-induced vibration velocity behind theexcavation surface to be higher than that in front of theexcavation surface According to the blasting-induced vi-bration velocity peak curves the vibration velocity peakwithin 10ndash15m in front and behind the explosive pointdrops rapidly attenuates slowly and finally tends to sta-bilize )erefore the vibration of the surrounding rocks inthe anterior tunnel within 10m behind the explosive point isinfluenced to a maximum extent thereby requiring keymonitoring in construction process

445 Effects of Anterior Tunnel Section )e calculationcondition was set as V-level surrounding rock bench cutmethod 30m buried depth and 1ndash6m net span )e sidewall bottom haunch and spandrel at the side that facesdetonation as well as spandrel haunch and side wall bottomat the side behind the detonation vault and floor centerwere chosen in the follow-up analysis Variation curves ofthe blasting-induced vibration velocity peak with net span atsectional positions are shown in Figure 10

Figure 10 shows that the blasting-induced vibrationvelocity peak which is approximately 20ndash25 times that onthe side behind the detonation at spandrel of the side facingwith the detonation in the anterior tunnel is the highest)is is because the spandrel of the side facing with thedetonation is in the intersection of the shared rock and rockstrata and the explosive stress wave may generate verystrong reflection effect on the interface accompanied withsuperposition of reflected wave stresses As a result stresswave which can amplify the blasting-induced vibrationvelocity on the interface is strengthened significantlySecondly the blasting-induced vibration velocity peak at thehaunch of the side facing with the detonation is about 6-7times that at the side behind the detonation )e minimumblasting-induced vibration velocity peak is at the wall foot ofthe side behind the detonation Generally the blasting-in-duced vibration velocity at the side facing with detonation inthe anterior tunnel is higher than that at the side behind

Full face excavationUpper benchLower bench

Side driftCRD

0

5

10

15

20

25

30

35

40

Vib

ratio

n ve

loci

ty p

eak

(cm

s)

1 2 3 4 5 60 7Net span (m)

Figure 8 Variation curves of vibration velocity peak with net spanunder different excavation methods

Explosive source 1Explosive source 2Explosive source 3

Explosive source 4Explosive source 5

0

2

4

6

8

10

12

Vib

ratio

n ve

loci

ty p

eak

(cm

s)

250 20ndash5 105 15ndash10ndash15ndash20ndash25Relative distance (m)

Figure 9 Variation curves of vibration velocity peak with relativedistance from explosive sources


detonation According to the vibration velocity peak curvethe blasting-induced vibration velocity is negatively corre-lated with net span Besides it attenuates quickly when thenet span is smaller than 4m but it becomes stable when thenet span is higher than 4m)erefore it is suggested to takespandrel and haunch at the side facing with detonation of theanterior tunnel as key points of vibration control duringblasting construction of transition section of the anteriortunnel

45 Comparative Analysis )e variation law of radial vi-bration velocity peak at spandrel haunch and arch foot ofthe side facing with detonation was concluded on the basis ofthe comparison between the measured results of radial vi-bration velocity in Table 2 and the numerical simulationresults (Figure 11)

)e average relative errors of the vibration speeds of thehaunch spandrel and arch foot are 35 78 and 98which are within a reasonable range based on the com-parison of the measured data of each measuring point inFigure 11 with the numerical simulation calculation valuerespectively )e accuracy and reliability of the numericalsimulation results are verified by the measured data

5 Blasting-Induced VibrationControl Measures

(1) Selection of tunnel excavation method the transitionsection of a branching-out tunnel has characteristicsof small buried depth short net span complicatedstructure and poor stability Long pipe-roof pro-tection shall be applied for advanced support beforethe excavation CRD or side drift method is rec-ommended )e footage driving cycle is controlled

within 05ndash15m and the ldquonew Austrian tunnelingmethodrdquo shall be adopted for supporting in time

(2) Controllingmaximal segment explosive quantity andchoosing reasonable cut blasting mode according toSodevrsquos empirical formula the maximal segmentexplosive quantity is proportional to blasting-in-duced vibration velocity )erefore decreasing themaximal segment explosive quantity is a majormethod of controlling the blasting-induced vibrationvelocity )e double wedge-shaped cut blasting waschosen combined with practical situations of thisproject )e big wedge-shaped cut-hole was changedinto second-level small wedge-shaped cut-hole )isnot only can decrease segment explosive quantity ofsmall wedge-shaped cut-hole but also can weaken theclamping effect of the first-level cut-hole explosionthus enabling it to control blasting-induced vibrationand improve the cut-hole explosion effect

(3) Selection of explosion interval and number of deto-nator segments according to feedback data and timelyadjusted explosion interval weakening interferenceeffect during explosion and avoiding superposition ofexplosive blasting waves decrease the blasting-in-duced vibration velocity peak significantly During theconstruction nine segments of detonators were set atthe upper left of the posterior tunnel and the deto-nation interval was set 50ndash140ms In particular itapplied floor blast-hole staged detonation which wasproven effective in reducing vibration

(4) Geological condition and distance from explosivesources vibration strength is related to blasting-inducedvibration propagationmedia Near the explosive sourcethe blasting-induced vibration velocity decreased con-tinuously with the increase in distance )ereforesections which have poor geological conditions and

Wall bottom facing theblastingHaunch facing theblastingSpandrel facing theblastingVault

Spandrel behind theblastingHaunch behind theblastingWall bottom behind theblastingFloor center

0

10

20

30

40

50

60

Vibr

atio

n ve

loci

ty p

eak

(cm

s)

1 2 3 70 4 65Net span at sectional position (m)

Figure 10 Variation curves of vibration velocity peak with netspan at sectional positions

Measured value (spandrel)Measured value (haunch)Measured value (arch foot)

Calculated value (spandrel)Calculated value (haunch)Calculated value (arch foot)

0

2

4

6

8

10

Vibr

atio

n ve

loci

ty p

eak

(cm

s)

1 2 30 4 65Monitoring point

Figure 11 Variation curve of radial vibration velocity peak atdifferent monitoring points


short distances between explosive excavation surfaceand the supporting structure shall be the key area ofvibration control It is recommended to choose theappropriate blasting scheme

6 Conclusions

)is paper mainly aims to study the influences of blastingexcavation in posterior tunnel of the transition section onsupporting structures of the anterior tunnel Based on thefield blasting-induced vibration monitoring datum andnumerical simulation presented in this study the followingconclusions can be drawn

(1) Influenced by posterior tunnel blasting the blasting-induced vibration velocity peak of shared rock in theanterior tunnel attenuates regularly along the ad-vancing direction )e blasting-induced vibrationvelocity peak behind the blasting excavation surfaceis higher than that in front of the blasting excavatingsurface )e region within 10m behind the blastingexcavation surface is the key position of blasting-induced vibration control in the transition section ofa branching-out tunnel

(2) CRD or side drift method is recommended for IV-level V-level and III-level surrounding rocks with netspan smaller than 3m in the transition section of abranching-out tunnel However the bench cutmethod is chosen for III-level surrounding rocks withnet span higher than 3m )e full-face excavationmethod is not recommended in the transition sectionV-level surrounding rocks have soft and broken rockstrata so weak or loose blasting shall be applied underthe assistance of mechanical excavation

(3) )e blasting-induced vibration velocity peak at thespandrel and haunch of the side facing with thedetonation in the anterior tunnel is the highest at20ndash25 and 6-7 times those at the spandrel andhaunch behind the detonation respectively )ere-fore these two sections are key positions to controlblasting-induced vibration velocity

(4) )e propagation laws of blasting-induced vibrationwave are related to the surrounding rock conditionburied depth construction method and net span inthe tunnel )e numerical simulation results furtheroptimize the blasting scheme )e maximum vi-bration velocity in monitoring is 835 cms provingthat the double wedge-shaped cut blasting and thefloor blast-hole staged detonation can control vi-bration velocity effectively

Data Availability

)e data sets used to support the findings of this study areincluded within the article

Conflicts of Interest

)e authors declare that they have no conflicts of interest

Acknowledgments

)is work was supported by the National Natural ScienceFoundation of China (no 51608183) the China Schol-arship Council (no 201808430341) and the NaturalScience Foundation of Hunan Province in China (no2018JJ3022)

References

[1] S Song S Li L Li et al ldquoModel test study on vibrationblasting of large cross-section tunnel with small clearance inhorizontal stratified surrounding rockrdquo Tunnelling and Un-derground Space Technology vol 92 p 103013 2019

[2] T-H Ling F Cao S Zhang L Zhang and D-P Gu ldquoBlastvibration characteristics of transition segment of a branchtunnelrdquo Journal of Vibration and Shock vol 37 no 2pp 43ndash50 2018

[3] L-Y Yu S-C Li X-H Guo and S-B Shi ldquoStudy of stabilityof transition segment for bifurcation tunnelrdquo China Journal ofHighway and Transport vol 24 no 1 pp 89ndash95 2011

[4] F Cao T-H Ling J-S Liu L Zhang and D-P GuldquoAnalysis on blasting vibration effect of shallow multi-archsection of bifurcated tunnelrdquo Journal of Highway andTransportation Research and Development vol 35 no 2pp 86ndash94 2018

[5] J Wang S Tang H Zheng C Zhou and M Zhu ldquoFlexuralbehavior of a 30-meter full-scale simply supported prestressedconcrete box girderrdquo Applied Sciences vol 10 no 9 p 30762020

[6] A Li D-L Zhang Q Fang J-W Luo L-Q Cao andZ-Y Sun ldquoSafety distance of shotcrete subjected toblasting vibration in large-span high-speed railway tun-nelsrdquo Shock And Vibration vol 2019 Article ID 242971314 pages 2019

[7] Y Xia N Jiang C Zhou and X Luo ldquoSafety assessment ofupper water pipeline under the blasting vibration induced bySubway tunnel excavationrdquo Engineering Failure Analysisvol 104 pp 626ndash642 2019

[8] S-C Li H-P Wang and X-F Zheng ldquoForked tunnel sta-bility analysis and its construction optimization researchrdquoChinese Journal of Rock Mechanics and Engineering vol 27no 3 pp 447ndash457 2008

[9] X-W Chai S-S Shi Y-F Yan J-G Li and L ZhangldquoKey blasting parameters for deep-hole excavation in anunderground tunnel of phosphorite minerdquo Advances inCivil Engineering vol 2019 Article ID 4924382 9 pages2019

[10] J Yang J Cai C Yao P Li Q Jiang and C ZhouldquoComparative study of tunnel blast-induced vibration ontunnel surfaces and inside surrounding rockrdquo Rock Me-chanics and Rock Engineering vol 52 no 11 pp 4747ndash47612019

[11] S Zhang W-C He Y-S Li D Hu and X Cai ldquoResearch onidentification of tunnel cavity fillings by time-energy densityanalysis based on wavelet transformrdquo Journal of China CoalSociety vol 44 no 11 pp 3504ndash3514 2019

[12] A Sharafat W A Tanoli G Raptis and J W Seo ldquoCon-trolled blasting in underground construction a case study of atunnel plug demolition in the Neelum Jhelum hydroelectricprojectrdquo Tunnelling and Underground Space Technologyvol 93 p 103098 2019

[13] J Chen H Yu A Bobet and Y Yuan ldquoShaking table tests oftransition tunnel connecting TBM and drill-and-blast


tunnelsrdquo Tunnelling and Underground Space Technologyvol 96 p 103197 2020

[14] N Jiang C-B Zhou X-D Luo and S-W Lu ldquoDamagecharacteristics of surrounding rock subjected to VCR miningblasting shockrdquo Shock and Vibration vol 2015 Article ID373021 8 pages 2015

[15] K Xu Q Deng L Cai S Ho and G Song ldquoDamage detectionof a concrete column subject to blast loads using embeddedpiezoceramic transducersrdquo Sensors vol 18 no 5 p 1377 2018

[16] J Yang W Lu M Chen P Yan and C Zhou ldquoMicroseisminduced by transient release of in situ stress during deep rockmass excavation by blastingrdquo Rock Mechanics and RockEngineering vol 46 no 4 pp 859ndash875 2012

[17] X Tian Z Song and J Wang ldquoStudy on the propagation lawof tunnel blasting vibration in stratum and blasting vibrationreduction technologyrdquo Soil Dynamics and Earthquake Engi-neering vol 126 p 105813 2019

[18] Z Hu K Du J-X Lai and Y-L Xie ldquoStatistical analysis ofinfluence of cover depth on loess tunnel deformation in NWChinardquo Advances in Civil Engineering vol 2019 Article ID2706976 12 pages 2019

[19] H-B Zhao Y Long X-H Li and L Lu ldquoExperimental andnumerical investigation of the effect of blast-induced vibra-tion from adjacent tunnel on existing tunnelrdquo KSCE Journalof Civil Engineering vol 20 no 1 pp 431ndash439 2015

[20] S Zhang Z-D Wang Y-S Li G-H Fu and Z-B LiuldquoCharacteristics analysis of blast vibration signals based onpattern adapted continuous wavelet energy spectrumrdquoBlasting vol 36 no 2 pp 105ndash110 2019

[21] GB 6722-2014 Safety Regulations for Blasting China Societyof Engineering Blasting Standards Press of China BeijingChina 2014

[22] W-B Lu Y Luo M Chen and D-Q Shu ldquoAn intro-duction to Chinese safety regulations for blasting vibra-tionrdquo Environmental Earth Sciences vol 67 no 7pp 1951ndash1959 2012

[23] X Liu Q Fang and D Zhang ldquoMechanical responses ofexisting tunnel due to new tunnelling below without clear-ancerdquo Tunnelling and Underground Space Technology vol 80pp 44ndash52 2018

[24] M Yin H Jiang Y Jiang Z Sun and Q Wu ldquoEffect of theexcavation clearance of an under-crossing shield tunnel onexisting shield tunnelsrdquo Tunnelling and Underground SpaceTechnology vol 78 pp 245ndash258 2018

[25] C-M Lin Z-C Zhang Q Zheng H-L Zheng and M LildquoStudy on the soft surrounding rocks stability and supportingparameters of two-to-fourlane tunnel of small clear-distanceby CD methodrdquo China Civil Engineering Journal vol 46no 7 pp 124ndash132 2013

[26] Z-G Zhu M-L Shu Y-Q Zhu and X-L Sun ldquoFieldmonitoring on blasting vibration and dynamic response ofultra-small spacing tunnelsrdquo Rock and Soil Mechanics vol 33no 12 pp 3747ndash3752 2012

[27] W-P Wu X-T Feng C-Q Zhang S-L Qiu and Z-H LildquoReinforcing mechanism and simulating method for rein-forcing effects of systemically grouted bolts in deep-buriedhard rock tunnelsrdquo Chinese Journal of Rock Mechanics andEngineering vol 31 no 1 pp 2711ndash2721 2012

[28] S-C Li W-S Zhu W-Z Chen and S-C Li ldquoApplication ofelasto-plastic large displacement finite element method to thestudy of deformation prediction of soft rock tunnelrdquo ChineseJournal of Rock Mechanics and Engineering vol 21 no 4pp 466ndash470 2002

[29] G-S Zhong L-P Ao and K Zhao ldquoInfluence of explosionparameters on wavelet packet frequency band energy distri-bution of blast vibrationrdquo Journal of Central South Universityvol 19 no 9 pp 2674ndash2680 2012

[30] Z Zhang C-B Zhou S-W Lu C Wu and C WangldquoPropagation characteristics of ground vibration induced bysubsurface blasting excavation in an ultra-shallow buriedunderpassrdquo Journal of Central South University (Science andTechnology) vol 48 no 8 pp 2119ndash2125 2017


changing the stress state and mechanical behavior of thesupporting structure in the tunnel and even local collapse oroverall instability of the supporting structure [7 8] )esefactors cause certain restraints against efficiency of con-struction and the engineering quality of the tunnel)erefore studying the influences of posterior tunnelconstruction on the stability of the anterior tunnel in thetransition section of branching-out tunnel has importantpractical significance [9 10]

With respect to the selection of tunnel constructionschemes the drilling and blasting method is a practicaltechnique for underground projects in traffic tunnel mu-nicipal-service tunnel hydraulic tunnel and mine tunnelbecause of its lower operation cost stronger adaptation andsimpler construction technique compared with tunnelboring machine and shield driving methods [11ndash13] Nev-ertheless partial energies generated by blast-hole explosionare used to break rocks whereas the highest energy istransformed into blast stress and seismic waves to prop-agate and connect microdefects on supporting structuresand rockmasses thereby decreasing the bearing capacities ofthe supporting structures and rock masses [14ndash16] Abun-dant field tests and numerical simulation studies on thepropagation of blasting-induced vibration in tunnel and itsinfluences on supporting structures and rock masses havebeen conducted to minimize blasting-related damage to thesupporting structures and rock masses [17ndash19] Howeverstudies on the attenuation laws of blasting-induced vibrationin a branching-out tunnel are limited In fact the transitionsection has become the key part in the blasting excavation ofa branching-out tunnel because of the great changes inchamber shapes and supporting structural forms in thetransition section of a branching-out tunnel )ereforeperforming numerical simulation and field monitoring teston blasting-induced vibration response features of thetransition section of a branching-out tunnel is crucial

)is study combined the engineering characteristics oftransition section of a branching-out tunnel to optimize thedesign of the tunnel blasting scheme and verified and an-alyzed the blasting scheme by using the measurement data ofblasting-induced vibration Subsequently the blasting-in-duced vibration response features of the transition section ofa branching-out tunnel under different buried depthssurrounding rock levels excavation technique shared rockthicknesses and net spans were carried out by using a finiteelement numerical simulation analysis Finally someblasting-induced vibration control measures were proposed)is study realized safety and stability during the controlledblasting construction of the transition section of abranching-out tunnel

2 Project Overview

A highway tunnel adopts the branching-out tunnel and islocated in karst middle and low mountainous areas A greattopographic relief along the highway is observed and theground elevation ranges between 42706 and 64027m )emaximum buried depth is 185m )e branching-out sec-tion of the tunnel is 1385m long and is divided into three

sections namely large-span multiarch and small net spansections )e plan view of the branching-out tunnel isshown in Figure 1 and the profile view of 1ndash1 is shown inFigure 2 )e tunnel transition section is located 20m infront and rear of the interface between the sandwichmultiarch tunnel and the neighborhood tunnel )echaracteristics of the transition section of the branching-out tunnel are mainly manifested as the constantlychanging width of the sandwich wall the abrupt cross-sectional shape of the transition section and the stressconcentration From the geological situation the sur-rounding rock of the tunnel is composed of slightlyweathered limestone with developed dissolution fissuresand relatively broken rock masses )e minimum net spanbetween two adjacent tunnels is 1m and the minimumburied depth is only 3m )e short net span small burieddepth complicated structural stresses and soft sur-rounding rocks in the tunnel bring extremely difficulties toblasting excavation

3 Design and Verification ofBlasting Parameters

31 Design of Tunnel Blasting Parameters According torelevant rules in Safety Regulations for Blasting (GB6722-2014) the critical value of safe particle vibration velocity is10ndash20 cms [20ndash22] Considering the structural uniquenessof the transition section in a branching-out tunnel the safetycritical value of blasting-induced vibration velocity wasdetermined as 10 cms In the blasting design the net span ofthe transition section was 2-3m )e buried depth andsurrounding rock level were set 25-35m and V-level re-spectively )e CRD method was applied to excavate rockmass )e CRD method in the posterior tunnel and blast-hole layout in the upper bench left Zone I are shown inFigure 3

Given that the vibration caused by cut-hole explosion onno-free face is the maximum the blasting parameters in theupper bench left Zone I of the posterior tunnel were going tobe optimized )e optimized blasting design parameters areshown in Table 1 and the blast-hole layout is shown inFigure 3 Double wedge-shaped cut blasting was applied todecrease single cut-hole blasting-induced vibration Super-position of blasting-induced vibration waves is avoided andthe blasting-induced vibration velocity is decreased byshortening the footage driving cycle decreasing maximalsegment explosive quantity and setting skip detonators toextend the interval time

32 Verification Analysis of Blasting-Induced Vibration DataBlasting-induced vibration in the anterior tunnel will bemonitored to investigate the influences of posterior tunnelblasting on the vibration of the anterior tunnel Blasting-induced vibration monitoring points on the section of theanterior tunnel were mainly set at the spandrel haunch andarch foot on the side facing with detonation Monitoringpoints were set symmetrically on the advancing andretreating directions around the axial line along the






1

1

Neighborhood tunnel

Hig

hway

subg

rade

Shared rock

10 405 88


e-sp

an tu

nnel

Multiarchtunnel

Multiarchtunnel

Driving direction

Driving direction

Sandwich wall


Interface


1224

Posterior tunnel

1224100~600

Anterior tunnel996


I

V

IV

VI

II

III

(a)

97150

100

621513

119

7

5

5

17

3 31 1 5

7

I

(b)











Explosive source


Anterior tunnel

Sandwich wall

(a)



55 5 532 4 51

(b)








Peos A 1 minusω

R1V1113888 1113889e

minusR1V+ B 1 minus

ωR2V

1113888 1113889eminusR2V

+ωE0

V

(1)



P F times Peos (2)





Monitoringpoints













43

radicSaSc

(3)



E E0 +SgEg

Ss

(4)





44 Results Analysis



150m

100m150m

40m

XY

Z

(a)

XY

Z

(b)




11 4200 524times104 769 42 1 03 85













0

2

4

6

8

10

12

Vib

ratio

n ve

loci

ty p

eak

(cm

s)

2 3 10050106541 20Buried depth (m)



0

10

20

30

40

50

60

Vibr

atio

n ve

loci

ty p

eak

(cm

s)

72 3 4 5 610Net span (m)










Side driftCRD

0

5

10

15

20

25

30

35

40

Vib

ratio

n ve

loci

ty p

eak

(cm

s)

1 2 3 4 5 60 7Net span (m)




0

2

4

6

8

10

12

Vib

ratio

n ve

loci

ty p

eak

(cm

s)















0

10

20

30

40

50

60

Vibr

atio

n ve

loci

ty p

eak

(cm

s)





0

2

4

6

8

10

Vibr

atio

n ve

loci

ty p

eak

(cm

s)





6 Conclusions






Data Availability




Acknowledgments


References






































1

1

Neighborhood tunnel

Hig

hway

subg

rade

Shared rock

10 405 88


e-sp

an tu

nnel

Multiarchtunnel

Multiarchtunnel

Driving direction

Driving direction

Sandwich wall


Interface


1224

Posterior tunnel

1224100~600

Anterior tunnel996


I

V

IV

VI

II

III

(a)

97150

100

621513

119

7

5

5

17

3 31 1 5

7

I

(b)











Explosive source


Anterior tunnel

Sandwich wall

(a)



55 5 532 4 51

(b)








Peos A 1 minusω

R1V1113888 1113889e

minusR1V+ B 1 minus

ωR2V

1113888 1113889eminusR2V

+ωE0

V

(1)



P F times Peos (2)





Monitoringpoints













43

radicSaSc

(3)



E E0 +SgEg

Ss

(4)





44 Results Analysis



150m

100m150m

40m

XY

Z

(a)

XY

Z

(b)




11 4200 524times104 769 42 1 03 85













0

2

4

6

8

10

12

Vib

ratio

n ve

loci

ty p

eak

(cm

s)

2 3 10050106541 20Buried depth (m)



0

10

20

30

40

50

60

Vibr

atio

n ve

loci

ty p

eak

(cm

s)

72 3 4 5 610Net span (m)










Side driftCRD

0

5

10

15

20

25

30

35

40

Vib

ratio

n ve

loci

ty p

eak

(cm

s)

1 2 3 4 5 60 7Net span (m)




0

2

4

6

8

10

12

Vib

ratio

n ve

loci

ty p

eak

(cm

s)















0

10

20

30

40

50

60

Vibr

atio

n ve

loci

ty p

eak

(cm

s)





0

2

4

6

8

10

Vibr

atio

n ve

loci

ty p

eak

(cm

s)





6 Conclusions






Data Availability




Acknowledgments


References










































Explosive source


Anterior tunnel

Sandwich wall

(a)



55 5 532 4 51

(b)








Peos A 1 minusω

R1V1113888 1113889e

minusR1V+ B 1 minus

ωR2V

1113888 1113889eminusR2V

+ωE0

V

(1)



P F times Peos (2)





Monitoringpoints













43

radicSaSc

(3)



E E0 +SgEg

Ss

(4)





44 Results Analysis



150m

100m150m

40m

XY

Z

(a)

XY

Z

(b)




11 4200 524times104 769 42 1 03 85













0

2

4

6

8

10

12

Vib

ratio

n ve

loci

ty p

eak

(cm

s)

2 3 10050106541 20Buried depth (m)



0

10

20

30

40

50

60

Vibr

atio

n ve

loci

ty p

eak

(cm

s)

72 3 4 5 610Net span (m)










Side driftCRD

0

5

10

15

20

25

30

35

40

Vib

ratio

n ve

loci

ty p

eak

(cm

s)

1 2 3 4 5 60 7Net span (m)




0

2

4

6

8

10

12

Vib

ratio

n ve

loci

ty p

eak

(cm

s)















0

10

20

30

40

50

60

Vibr

atio

n ve

loci

ty p

eak

(cm

s)





0

2

4

6

8

10

Vibr

atio

n ve

loci

ty p

eak

(cm

s)





6 Conclusions






Data Availability




Acknowledgments


References







































Peos A 1 minusω

R1V1113888 1113889e

minusR1V+ B 1 minus

ωR2V

1113888 1113889eminusR2V

+ωE0

V

(1)



P F times Peos (2)





Monitoringpoints













43

radicSaSc

(3)



E E0 +SgEg

Ss

(4)





44 Results Analysis



150m

100m150m

40m

XY

Z

(a)

XY

Z

(b)




11 4200 524times104 769 42 1 03 85













0

2

4

6

8

10

12

Vib

ratio

n ve

loci

ty p

eak

(cm

s)

2 3 10050106541 20Buried depth (m)



0

10

20

30

40

50

60

Vibr

atio

n ve

loci

ty p

eak

(cm

s)

72 3 4 5 610Net span (m)










Side driftCRD

0

5

10

15

20

25

30

35

40

Vib

ratio

n ve

loci

ty p

eak

(cm

s)

1 2 3 4 5 60 7Net span (m)




0

2

4

6

8

10

12

Vib

ratio

n ve

loci

ty p

eak

(cm

s)















0

10

20

30

40

50

60

Vibr

atio

n ve

loci

ty p

eak

(cm

s)





0

2

4

6

8

10

Vibr

atio

n ve

loci

ty p

eak

(cm

s)





6 Conclusions






Data Availability




Acknowledgments


References




































43

radicSaSc

(3)



E E0 +SgEg

Ss

(4)





44 Results Analysis



150m

100m150m

40m

XY

Z

(a)

XY

Z

(b)




11 4200 524times104 769 42 1 03 85













0

2

4

6

8

10

12

Vib

ratio

n ve

loci

ty p

eak

(cm

s)

2 3 10050106541 20Buried depth (m)



0

10

20

30

40

50

60

Vibr

atio

n ve

loci

ty p

eak

(cm

s)

72 3 4 5 610Net span (m)










Side driftCRD

0

5

10

15

20

25

30

35

40

Vib

ratio

n ve

loci

ty p

eak

(cm

s)

1 2 3 4 5 60 7Net span (m)




0

2

4

6

8

10

12

Vib

ratio

n ve

loci

ty p

eak

(cm

s)















0

10

20

30

40

50

60

Vibr

atio

n ve

loci

ty p

eak

(cm

s)





0

2

4

6

8

10

Vibr

atio

n ve

loci

ty p

eak

(cm

s)





6 Conclusions






Data Availability




Acknowledgments


References













































0

2

4

6

8

10

12

Vib

ratio

n ve

loci

ty p

eak

(cm

s)

2 3 10050106541 20Buried depth (m)



0

10

20

30

40

50

60

Vibr

atio

n ve

loci

ty p

eak

(cm

s)

72 3 4 5 610Net span (m)










Side driftCRD

0

5

10

15

20

25

30

35

40

Vib

ratio

n ve

loci

ty p

eak

(cm

s)

1 2 3 4 5 60 7Net span (m)




0

2

4

6

8

10

12

Vib

ratio

n ve

loci

ty p

eak

(cm

s)















0

10

20

30

40

50

60

Vibr

atio

n ve

loci

ty p

eak

(cm

s)





0

2

4

6

8

10

Vibr

atio

n ve

loci

ty p

eak

(cm

s)





6 Conclusions






Data Availability




Acknowledgments


References









































Side driftCRD

0

5

10

15

20

25

30

35

40

Vib

ratio

n ve

loci

ty p

eak

(cm

s)

1 2 3 4 5 60 7Net span (m)




0

2

4

6

8

10

12

Vib

ratio

n ve

loci

ty p

eak

(cm

s)















0

10

20

30

40

50

60

Vibr

atio

n ve

loci

ty p

eak

(cm

s)





0

2

4

6

8

10

Vibr

atio

n ve

loci

ty p

eak

(cm

s)





6 Conclusions






Data Availability




Acknowledgments


References













































0

10

20

30

40

50

60

Vibr

atio

n ve

loci

ty p

eak

(cm

s)





0

2

4

6

8

10

Vibr

atio

n ve

loci

ty p

eak

(cm

s)





6 Conclusions






Data Availability




Acknowledgments


References



































6 Conclusions






Data Availability




Acknowledgments


References





















































Documents

Blasting-InducedVibrationResponseoftheTransitionSectionin