Research Article Bearing Capacity Estimation of Bridge ...downloads.hindawi.com/journals/sv/2016/4187026.pdf · Research Article Bearing Capacity Estimation of Bridge Piles Using

Research ArticleBearing Capacity Estimation of Bridge Piles Using the ImpulseTransient Response Method

Meng Ma1 Jianlei Liu2 Zaitian Ke2 and Yan Gao2

1School of Civil Engineering Beijing Jiaotong University Beijing 100044 China2Railway Engineering Research Institute China Academy of Railway Sciences Beijing 100081 China

Correspondence should be addressed to Meng Ma mameng 02231250163com

Received 10 July 2015 Accepted 18 October 2015

Academic Editor Mickael Lallart

Copyright copy 2016 Meng Ma et alThis is an open access article distributed under theCreative CommonsAttribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

A bearing capacity estimation method for bridge piles was developed In this method the pulse echo test was used to select theintact piles the dynamic stiffness was obtained by the impulse transient response test A total of 680 bridge piles were tested andtheir capacities were estimated Finally core drilling analysis was used to check the reliability of this method The results showthat for intact piles an obvious positive correlation exits between the dynamic stiffness and bearing capacity of the piles The coredrilling analysis proved that the estimation method was reliable

1 Introduction

The ultimate capacity of a single pile is regarded as oneof the most important issues in pile testing [1] The staticload test (SLT) is considered to be the most reliable methodto evaluate the pile capacity however it can be expensiveand time consuming As a classic dynamic loading testmethod the high-strain dynamic pile testing (HSDPT) ismore economical and efficient than the SLTTheHSDPT testsdeep foundations to obtain information about their capacityand integrity and in some cases tomonitor their installation

The low-strain dynamic test also known as the pulse echomethod (PEM) is a method that is usually used to checkthe integrity of the pile The PEM is widely used [2ndash4] andrecommended by many codes [5ndash8] The transient responsemethod (TRM) also known as the mechanical mobilitymethod is a method similar to the PEM and was proposed inthe 1960ssim1970s [9] TRM analyses both the velocity and theforce signals in the frequency domainThe velocity spectrumis divided by the force spectrum to determine the mobility ormechanical admittance spectrum [10] which helps providemore information compared to the PEM to identify defectsnear the top of the pile [11] An idealised test graph of pilemobility versus frequency is shown in Figure 1 Some keyinformation from the graph such as the peakmean mobility

ratio mobility and damping is widely used to evaluate thepile integrity and pile length [12ndash15] Another importantparameter from the curve was the dynamic stiffness (119870119889) 119870119889is the slope of the low frequency (ie lt50Hz) linear portionof the graph from the origin to the first peak This value issensitive to the stiffness of the pile shaft under compression

For practical engineering the STL and HSDPT are notpermitted for a bridge in service with a large number ofpiles In this paper because many piles with different defectswere evaluated along a highway bridge with a length ofapproximately 20 km it is urgent to evaluate piles withinsufficient capacity and reinforce them Generally the low-strain dynamic test especially the PEM can only provideintegrity information so it should not be used as the solefactor in establishing pile acceptance or rejection [5] Inthis paper to provide a quantitative capacity estimation theTRM is developed and includes three steps (1) preanalysis(2) general investigation measurement and (3) check andverification The TRM test is performed on all 680 piles Inthe TRM test a drop hammer weighing 106 kg was employedinstead of a small hand hammer to excite the first naturalfrequency of the pile The dynamic stiffness 119870119889 for eachpile can be obtained from the TRM test The PEM test isused as an assisting technique to select the piles with goodintegrity Regular values of 119870119889 for intact piles can be found

Hindawi Publishing CorporationShock and VibrationVolume 2016 Article ID 4187026 8 pageshttpdxdoiorg10115520164187026

2 Shock and VibrationM

obili

ty o

r mec

hani

cal a

dmitt

ance

(vel

ocity

forc

e)

Frequency f (Hz)

1

Frequency offirst resonance

Δf Δf

MOQmPm

Kd

Figure 1 Idealised results of a vibration test by the TRM [8]

Accordingly a pile may have a low capacity if its 119870119889 isobviously smaller than the regular values Finally the coredrilling analysis is performed to check the estimation results

2 Capacity Estimation Method forBridge Piles

To estimate the bearing capacity for a large number of pilesthe TRM was developed when the pile loading test and high-strain test were not allowed

The dynamic stiffness 119870119889 can be calculated by

119870119889 (119891) =

2120587119891

1003816

1003816

1003816

1003816

119881 (119891) 119865 (119891)

1003816

1003816

1003816

1003816

(1)

where 119881(119891) and 119865(119891) are the velocity and force signals in thefrequency domain When 119891 rarr 0 the value of the dynamicstiffness approaches the static stiffness or 119870119889 rarr 119870119904 Inpractice however the frequency of the dynamic impulsecannot be 0Hz Therefore a coefficient 120572 is introduced hereto describe the ratio between the dynamic and static stiffness120572 = 119870119889119870119904 Then the pile bearing capacity 119876 can becalculated by

119876 =

119870119889119878119886

120572

(2)

where 119878119886 is the guideline value of the pile settlementTo evaluate a large number of piles for a long highway

bridge the following three steps are proposed (Figure 2)

(1) Preanalysis Some typical piles were selected to performthe TRM test and PEM integrity test Then the data of theintact piles are used to calculate 120572 The value of 120572 is adjusteddynamically

(2) General Investigation Measurement Measure all of thepiles and calculate 119876 by (1) Compare 119876 with the design

load 119875 If 119876 gt 119875 the capacity is sufficient otherwisereinforcement of the pile is suggested

(3) Checking and Verification Verify the evaluation results bythe PEM and pile core drilling

To reduce the measurement and analysis errors theheight of the drop hammer and sensor location are the samein all of the TRM tests

Because destructive loading tests are not allowed forexisting piles the designed allowable capacity is used as arough estimation of the pile assuming good integrity

In the preanalysis step the intact piles are selected usingthe PEM and coefficient 120572 was calculated by

120572 =

119870119889119878119886

[119877119886]

(3)

where [119877119886] is designed allowable capacity calculated by JTGD63-2007 ldquoCode for Design of Ground Base and FoundationofHighway Bridges andCulvertsrdquo [16] For cast-in-situ drillingfriction piles the capacity is expressed as

[119877119886] =

1

2

119906

119899

sum

119894=1

119902119894119896119897119894 + 119860119901119902119903

119902119903 = 1198980120582 [[1198911198860] + 11989621205742 (ℎ minus 3)]

(4)

and for cast-in-situ end-bearing piles the bearing capacitycan be expressed as

[119877119886] = 1198881119860119901119891119903119896 + 119906

119898

sum

119894=1

1198882119894ℎ119894119891119903119896119894 +

1

2

120577119904119906

119899

sum

119894=1

119897119894119902119894119896 (5)

where 119906 is the perimeter 119860119901 is the cross sectional area at thepile end 119899 is the number of soil layers 119897119894 is the thickness ofthe 119894th soil layer 119902119894119896 is standard value of the lateral frictionfor the 119894th soil 119902119903 is the soil allowable capacity at the pileend [1198911198860] is the basic soil allowable capacity at the pile endℎ is the embedded depth of the pile end 1198962 is the revisedcoefficient of allowable capacity which changes with depth120574 is the weighted average unit weight 119891119903119896 is the standardvalue of the saturated uniaxial compressive strength of therock at the pile end ℎ119894 is the thickness of the 119894th rock layer119898 is the number of rock layers in which strong and fullyweathered rocks are not included but are considered to be asoil layer instead and 120582 1198980 1198881 1198882119894 and 120577119904 are all coefficientsthe guideline value of which can be obtained from the code

To improve the calculation accuracy in (4) and (5) 48 soilsamples were obtained from core drilling near different piersalong the highway bridge Figure 3 shows some typical soilsamples

With the small hammer (usuallylt10 kg) in the traditionalPEM and TRM tests the great mass of the pile cap absorbedmost energy of the applied impact so the amplitude of thereflected wave from the pile bottom was unclear and difficultto identify [17] To solve this problem in the TRM test a drophammer weighing 106 kg was used so that the input energycan excite the first natural frequency of the pile In the PEMtest a hammer weighing 30 kg was used and the sensor was

Shock and Vibration 3

(pretest) (adjust dynamically)

(evaluation test)

Design load P

Calculate capacity Q

Capacity evaluation

Select the intact piles byPEM and calculate theirallowable capacity [

Integrity analysis byPEM and pile core

drilling (verification)

3 Checking and verification

1 Preanalysis

2 General investigation measurement

Measure Kd by TRM

Measure Kd by TRM Coefficient 120572

Ra]

Figure 2 Flowchart of the bridge pile evaluation and analysis

(a) Near Pier number D8-37 (b) Near Pier number H1-A5

Figure 3 Typical soil samples from core drilling

installed directly on top of the pile by drilling on the cap50 cm from the bottom of the cap (Figure 4)

3 Dynamic Measurement and Analysis

31 Dynamic Stiffness By analysing both the velocity and theforce signals at the pile top in the frequency domain themobility can be calculated by

119866V (119891) =

119878119865119881 (119891)

119878119865119865 (119891)

(6)

where 119878119865119881(119891) is the cross power spectrum between the forceand velocity and 119878119865119865(119891) is the auto power spectrum of theforce

Before measuring clear the miscellaneous fill from thepile caps and polish the cap surface with an angle grinder(Figure 5) to ensure that the sensors collect the verticalsignals

Figure 6 shows the typical mobility responses of twoneighbouring piles under the same cap Similar curvesbelow 50Hz can be observed which provide the basis forthe dynamic stiffness analysis Figure 7 shows the dynamicstiffness of the two piles The steady value of 119870119889 can be

found between 10 and 30Hz therefore the average 119870119889 wascalculated between these frequencies for each pile

32 Correlation between Dynamic Stiffness and BearingCapacity In total 680 piles have been measured The aver-aged dynamic stiffness was calculated from the measure-ments and the allowable bearing capacity was estimatedusing (3) or (4) for each pile

Figure 8(a) shows the relationship between the dynamicstiffness and estimated capacity In general the allowablecapacity increases as dynamic stiffness increases The mea-sured samples were generally within 4sim8GNm however theallowable bearing capacity varied greatly This was becausethe estimated capacity was based on the assumption that allof the piles were intact In practice different levels of defectswere found for a large number of the piles To eliminate thisdisadvantage integrity tests were performed using the PEMand then 188 typical integrated samples were selected andreplotted in Figure 8(b) Then a good positive relationshipbetween the dynamic stiffness and bearing capacity wasobserved Therefore the dynamic stiffness can be used as anearly warning for the capacity evaluation when the measuredvalue is obviously low

4 Shock and Vibration

cm50

Sensor

Mortar

Hammer

Figure 4 Sensor installed on top of the pile during the PEM test

Pier

Polis

hing

of m

easu

rem

ent p

oint

Pile

loca

tion

Figure 5 Surface polishing where the sensors are located

33 Analysis of Coefficient 120572 In the preanalysis step coef-ficient 120572 was calculated by (2) and adjusted dynamicallyFinally for friction piles andmost end-bearing piles the valueof 120572 was estimated to be 466 for very long end-bearing piles(length gt26m) the value of 120572 was estimated to be 23

The typical 188 intact pile samples (Figure 8(b)) were usedto verify the estimation values of 120572 The results are shownin Figure 9 One can observe that (1) more than 90 of thefriction pile samples have a value of 120572 smaller than 466which ensures a safe estimation of the pile bearing capacity(2) all of the end-bearing pile samples shorter than 26m havean 120572 smaller than 466 and (3) most of the end-bearing pilesamples longer than 26m have an 120572 smaller than 23 exceptfor four samples that have an120572 value that is slightly larger than23 In general the value of 120572 estimated in the preanalysis stepprovides a good basis for the capacity evaluation of bridgepiles

0 100 200 300 40000

Pile 1Pile 2

Mob

ility

(mm

sN

)

Frequency (Hz)

60

50

40

30

20

10

times10minus5

Figure 6 Typical mobility curves

34 Evaluation of the Pile Bearing Capacity The 680 pileswere evaluated using the method introduced in Figure 2Figure 10 shows the relation between the estimated bearingcapacity 119876 and design load 119875 Based on static analysisapproximately 54 of the piles need to be reinforced because119876 lt 119875 which occurred in different two cases One case wascaused by the large design load which was approximately8000 kN The estimated capacity cannot bear this large loadalthough these piles are intact and without defects Theother case was caused by different types of pile defects Themeasured low dynamic stiffness of these piles the designloads of which were between 4000 and 5000 kN led to a lowestimated capacity


0 400300200100

0

0 8070605040302010Frequency (Hz)

Pile 1Pile 2

Frequency (Hz)

Kd

(Nm

)

Kd

(Nm

)

1

2

3

4

5times1011

minus1

minus40

minus20

40times1010

20

00

Figure 7 Typical dynamic stiffness curves

2 4 6 8 10 12 14 16 18 20

Allo

wab

le b

earin

g ca

paci

ty (k

N)

106

105

104

103

102

101

100

Measured Kd (GNm)

(a)

2 4 6 8 10 12 14 16 18 20

Allo

wab

le b

earin

g ca

paci

ty (k

N)

Fitting line

106

105

104

103

102

101

100

Measured Kd (GNm)

(b)

Figure 8 The relation between the dynamic stiffness and bearing capacity (a) for all piles (680 samples) and (b) for typical intact piles (188samples)

Further analysis of the piles with the design loads between4000 and 5000 kN as shown in Figure 11 shows that thedynamic stiffness of the piles with insufficient capacitieswas obviously lower than the piles with sufficient capacitiesTherefore the dynamic stiffness as an evaluation descriptorplays a beneficial role in evaluating piles of the same type andsimilar design load

4 Core Drilling Analysis

To validate the estimation method proposed in this paper 80random pile samples were used to perform the core drillinganalysis Based on the integrity and defects of the core drillingsamples different classes fromA to I were defined A detaileddescription of the classes is listed in Table 1 by the aspects ofthe pile concrete necking segregation and other defects


0 10 20 30 400

2

4

6

8

Friction pileEnd-bearing pile

Coe

ffici

ent 120572

Designed pile length (m)

Figure 9 Typical coefficient 120572 of bridge piles (188 samples)

0 2000 4000 6000 8000 10000 120000

5000

10000

15000

20000

Q lt P reinforcement is needed

Q = P

Estim

ated

bea

ring

capa

city

Q (k

N)

Design load P (kN)

Q gt P capacity is enough

Figure 10 Relationship between the calculated bearing capacity andbearing design load (680 samples)

The sample number for each class was also counted andplotted in Figure 12 Pictures of typical core drilling samplesare shown in Figure 13 In general a smaller value of QPrelates to more obvious defects and poor integrity in thedrilling samples There were 45 piles with high necking orsegregation which accounts for 882 of the 51 piles with avalue of QP lt 1 There were 21 piles without necking andsegregation which accounts for 724 of the 29 piles witha value of 119876119875 lt 1 The above core drilling analysis showssimilar estimation results which shows that the estimationmethod for the pile bearing capacity is reliable

5 Conclusions

(1) The dynamic stiffness obtained from the pile mobilitycurve is a sensitive index under compression load

5 10 15 20 25 300

3

6

9

12

15

Capacity is enoughCapacity is not enough

Ratio of length by diameter (mm)

Kd

(GN

m)

Figure 11 Dynamic stiffness of the friction piles

Table 1 Classification of the pile quality

Class Pile concrete Necking Segregation Otherdefects

A Loose and poor mdash High mdashB Fine Middle High mdash

C Fine Low LowBad jointwith pile

capD Fine High mdash mdash

E Good mdash Middle Low toedebris

F Good mdash Low mdashG Good mdash mdash Toe debrisH Good mdash mdash mdash

I Good mdash mdash Partlysurface pore

(2) For intact piles an obvious positive correlation isfound between the dynamic stiffness and bearing capacity ofthe piles

(3) The values of the dynamic stiffness are good forevaluating the bearing capacity of piles when they bearsimilar design loadsThe core drilling analysis proved that theestimation method was reliable

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper


0

4

8

12

16

20

24

28

I

H

G

F

E

D

C

BSam

ple n

umbe

r

QP

lt085 085sim1 1sim115 gt115

A

Figure 12 Histogram for piles with different defect classifications

(a) 119876119875 lt 085 (b) 085 lt 119876119875 lt 1

(c) 1 lt 119876119875 lt 115 (d) 119876119875 gt 115

Figure 13 Pictures of typical core drilling samples

Acknowledgment

The authors gratefully acknowledge the support of the Re-search Fund from Beijing Jiaotong University (Project no2014RC033)

References

[1] N Q Huy ldquoLiterature reviewmdashquasi-static and dynamic pileload testrdquo Primarily Report on Non-Static Pile Load Test TUDelft Delft The Netherlands 2010

[2] Z T Lu Z LWang andD J Liu ldquoStudy on low-strain integritytesting of pipe-pile using the elastodynamic finite integrationtechniquerdquo International Journal for Numerical and AnalyticalMethods in Geomechanics vol 37 no 5 pp 536ndash550 2013

[3] S-H Ni L Lehmann J-J Charng and K-F Lo ldquoLow-strainintegrity testing of drilled piles with high slenderness ratiordquoComputers and Geotechnics vol 33 no 6-7 pp 283ndash293 2006

[4] S-H Ni K-F Lo L Lehmann and Y-H Huang ldquoTime-frequency analyses of pile-integrity testing using wavelet trans-formrdquo Computers and Geotechnics vol 35 no 4 pp 600ndash6072008


[5] ASTM International ldquoStandard test method for low strainimpact integrity testingrdquo ASTM D5882-07 ASTM Interna-tional West Conshohocken Pa USA 2013

[6] Australian Standard ldquoStandard piling-design and installationrdquoTech Rep AS2159-2009 2010

[7] Chinese Code ldquoTechnical code for testing of building founda-tion pilesrdquo JGJ 106-2006 Chinese Code 2006

[8] GEO ldquoFoundation design and constructionrdquo GEO Publication12006 Geotechnical Control Office Hong Kong 2006

[9] A G Davis and C S Dumm ldquoFrom theory to field experiencewith the non-destructive vibration testingrdquo Proceeding of Insti-tution of Civil Engineers Part 2 no 57 pp 571ndash593 1974

[10] L Liang and J Beim ldquoEffect of soil resistance on the low strainmobility response of piles using impulse transient responsemethodrdquo in Proceedings of the 8th International Conference onthe Application of Stress Wave Theory to Piles pp 435ndash441 IOSPress Lisbon Portugal September 2008

[11] F Rausche ldquoNon-destructive evaluation of deep foundationsrdquoin Proceedings of the 5th International Conference on CaseHistories in Geotechnical Engineering pp 1ndash9 New York NYUSA April 2004

[12] AGDavis ldquoThenondestructive impulse response test inNorthAmerica 1985ndash2001rdquo NDT amp E International vol 36 no 4 pp185ndash193 2003

[13] S T Liao and J M Roesset ldquoDynamic response of intactpiles to impulse loadsrdquo International Journal for Numerical andAnalytical Methods in Geomechanics vol 21 no 4 pp 255ndash2751997

[14] K F Lo S H Ni and Y H Huang ldquoNon-destructive test forpile beneath bridge in the time frequency and time-frequencydomains using transient loadingrdquo Nonlinear Dynamics vol 62no 1-2 pp 349ndash360 2010

[15] N Massoudi and W Teffera ldquoNon-destructive testing of pilesusing the low strain integrity methodrdquo in Proceedings of the5th International Conference on Case Histories in GeotechnicalEngineering New York NY USA April 2004

[16] Chinese Code ldquoCode for design of ground base and foundationof highway bridges and culvertsrdquo JTG D63-2007 China Com-munications Press Beijing China 2007

[17] Y-H Huang and S-H Ni ldquoExperimental study for the evalua-tion of stress wave approaches on a group pile foundationrdquoNDTamp E International vol 47 pp 134ndash143 2012

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Control Scienceand Engineering

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Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design



Shock and Vibration


Civil EngineeringAdvances in

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Journal of

Advances inOptoElectronics


Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of


Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014


Chemical EngineeringInternational Journal of Antennas and

Propagation




Navigation and Observation



DistributedSensor Networks


2 Shock and VibrationM

obili

ty o

r mec

hani

cal a

dmitt

ance

(vel

ocity

forc

e)

Frequency f (Hz)

1

Frequency offirst resonance

Δf Δf

MOQmPm

Kd

Figure 1 Idealised results of a vibration test by the TRM [8]

Accordingly a pile may have a low capacity if its 119870119889 isobviously smaller than the regular values Finally the coredrilling analysis is performed to check the estimation results

2 Capacity Estimation Method forBridge Piles

To estimate the bearing capacity for a large number of pilesthe TRM was developed when the pile loading test and high-strain test were not allowed

The dynamic stiffness 119870119889 can be calculated by

119870119889 (119891) =

2120587119891

1003816

1003816

1003816

1003816

119881 (119891) 119865 (119891)

1003816

1003816

1003816

1003816

(1)

where 119881(119891) and 119865(119891) are the velocity and force signals in thefrequency domain When 119891 rarr 0 the value of the dynamicstiffness approaches the static stiffness or 119870119889 rarr 119870119904 Inpractice however the frequency of the dynamic impulsecannot be 0Hz Therefore a coefficient 120572 is introduced hereto describe the ratio between the dynamic and static stiffness120572 = 119870119889119870119904 Then the pile bearing capacity 119876 can becalculated by

119876 =

119870119889119878119886

120572

(2)

where 119878119886 is the guideline value of the pile settlementTo evaluate a large number of piles for a long highway

bridge the following three steps are proposed (Figure 2)

(1) Preanalysis Some typical piles were selected to performthe TRM test and PEM integrity test Then the data of theintact piles are used to calculate 120572 The value of 120572 is adjusteddynamically

(2) General Investigation Measurement Measure all of thepiles and calculate 119876 by (1) Compare 119876 with the design

load 119875 If 119876 gt 119875 the capacity is sufficient otherwisereinforcement of the pile is suggested

(3) Checking and Verification Verify the evaluation results bythe PEM and pile core drilling

To reduce the measurement and analysis errors theheight of the drop hammer and sensor location are the samein all of the TRM tests

Because destructive loading tests are not allowed forexisting piles the designed allowable capacity is used as arough estimation of the pile assuming good integrity

In the preanalysis step the intact piles are selected usingthe PEM and coefficient 120572 was calculated by

120572 =

119870119889119878119886

[119877119886]

(3)

where [119877119886] is designed allowable capacity calculated by JTGD63-2007 ldquoCode for Design of Ground Base and FoundationofHighway Bridges andCulvertsrdquo [16] For cast-in-situ drillingfriction piles the capacity is expressed as

[119877119886] =

1

2

119906

119899

sum

119894=1

119902119894119896119897119894 + 119860119901119902119903

119902119903 = 1198980120582 [[1198911198860] + 11989621205742 (ℎ minus 3)]

(4)

and for cast-in-situ end-bearing piles the bearing capacitycan be expressed as

[119877119886] = 1198881119860119901119891119903119896 + 119906

119898

sum

119894=1

1198882119894ℎ119894119891119903119896119894 +

1

2

120577119904119906

119899

sum

119894=1

119897119894119902119894119896 (5)

where 119906 is the perimeter 119860119901 is the cross sectional area at thepile end 119899 is the number of soil layers 119897119894 is the thickness ofthe 119894th soil layer 119902119894119896 is standard value of the lateral frictionfor the 119894th soil 119902119903 is the soil allowable capacity at the pileend [1198911198860] is the basic soil allowable capacity at the pile endℎ is the embedded depth of the pile end 1198962 is the revisedcoefficient of allowable capacity which changes with depth120574 is the weighted average unit weight 119891119903119896 is the standardvalue of the saturated uniaxial compressive strength of therock at the pile end ℎ119894 is the thickness of the 119894th rock layer119898 is the number of rock layers in which strong and fullyweathered rocks are not included but are considered to be asoil layer instead and 120582 1198980 1198881 1198882119894 and 120577119904 are all coefficientsthe guideline value of which can be obtained from the code

To improve the calculation accuracy in (4) and (5) 48 soilsamples were obtained from core drilling near different piersalong the highway bridge Figure 3 shows some typical soilsamples

With the small hammer (usuallylt10 kg) in the traditionalPEM and TRM tests the great mass of the pile cap absorbedmost energy of the applied impact so the amplitude of thereflected wave from the pile bottom was unclear and difficultto identify [17] To solve this problem in the TRM test a drophammer weighing 106 kg was used so that the input energycan excite the first natural frequency of the pile In the PEMtest a hammer weighing 30 kg was used and the sensor was



(evaluation test)

Design load P


Capacity evaluation





1 Preanalysis


Measure Kd by TRM


Ra]







119866V (119891) =

119878119865119881 (119891)

119878119865119865 (119891)

(6)








cm50

Sensor

Mortar

Hammer


Pier

Polis

hing

of m

easu

rem

ent p

oint

Pile

loca

tion




0 100 200 300 40000

Pile 1Pile 2

Mob

ility

(mm

sN

)

Frequency (Hz)

60

50

40

30

20

10

times10minus5




0 400300200100

0

0 8070605040302010Frequency (Hz)

Pile 1Pile 2

Frequency (Hz)

Kd

(Nm

)

Kd

(Nm

)

1

2

3

4

5times1011

minus1

minus40

minus20

40times1010

20

00


2 4 6 8 10 12 14 16 18 20

Allo

wab

le b

earin

g ca

paci

ty (k

N)

106

105

104

103

102

101

100

Measured Kd (GNm)

(a)

2 4 6 8 10 12 14 16 18 20

Allo

wab

le b

earin

g ca

paci

ty (k

N)

Fitting line

106

105

104

103

102

101

100

Measured Kd (GNm)

(b)






0 10 20 30 400

2

4

6

8


Coe

ffici

ent 120572



0 2000 4000 6000 8000 10000 120000

5000

10000

15000

20000


Q = P

Estim

ated

bea

ring

capa

city

Q (k

N)

Design load P (kN)




5 Conclusions


5 10 15 20 25 300

3

6

9

12

15



Kd

(GN

m)















0

4

8

12

16

20

24

28

I

H

G

F

E

D

C

BSam

ple n

umbe

r

QP

lt085 085sim1 1sim115 gt115

A


(a) 119876119875 lt 085 (b) 085 lt 119876119875 lt 1

(c) 1 lt 119876119875 lt 115 (d) 119876119875 gt 115


Acknowledgment


References





















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











(evaluation test)

Design load P


Capacity evaluation





1 Preanalysis


Measure Kd by TRM


Ra]







119866V (119891) =

119878119865119881 (119891)

119878119865119865 (119891)

(6)








cm50

Sensor

Mortar

Hammer


Pier

Polis

hing

of m

easu

rem

ent p

oint

Pile

loca

tion




0 100 200 300 40000

Pile 1Pile 2

Mob

ility

(mm

sN

)

Frequency (Hz)

60

50

40

30

20

10

times10minus5




0 400300200100

0

0 8070605040302010Frequency (Hz)

Pile 1Pile 2

Frequency (Hz)

Kd

(Nm

)

Kd

(Nm

)

1

2

3

4

5times1011

minus1

minus40

minus20

40times1010

20

00


2 4 6 8 10 12 14 16 18 20

Allo

wab

le b

earin

g ca

paci

ty (k

N)

106

105

104

103

102

101

100

Measured Kd (GNm)

(a)

2 4 6 8 10 12 14 16 18 20

Allo

wab

le b

earin

g ca

paci

ty (k

N)

Fitting line

106

105

104

103

102

101

100

Measured Kd (GNm)

(b)






0 10 20 30 400

2

4

6

8


Coe

ffici

ent 120572



0 2000 4000 6000 8000 10000 120000

5000

10000

15000

20000


Q = P

Estim

ated

bea

ring

capa

city

Q (k

N)

Design load P (kN)




5 Conclusions


5 10 15 20 25 300

3

6

9

12

15



Kd

(GN

m)















0

4

8

12

16

20

24

28

I

H

G

F

E

D

C

BSam

ple n

umbe

r

QP

lt085 085sim1 1sim115 gt115

A


(a) 119876119875 lt 085 (b) 085 lt 119876119875 lt 1

(c) 1 lt 119876119875 lt 115 (d) 119876119875 gt 115


Acknowledgment


References





















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










cm50

Sensor

Mortar

Hammer


Pier

Polis

hing

of m

easu

rem

ent p

oint

Pile

loca

tion




0 100 200 300 40000

Pile 1Pile 2

Mob

ility

(mm

sN

)

Frequency (Hz)

60

50

40

30

20

10

times10minus5




0 400300200100

0

0 8070605040302010Frequency (Hz)

Pile 1Pile 2

Frequency (Hz)

Kd

(Nm

)

Kd

(Nm

)

1

2

3

4

5times1011

minus1

minus40

minus20

40times1010

20

00


2 4 6 8 10 12 14 16 18 20

Allo

wab

le b

earin

g ca

paci

ty (k

N)

106

105

104

103

102

101

100

Measured Kd (GNm)

(a)

2 4 6 8 10 12 14 16 18 20

Allo

wab

le b

earin

g ca

paci

ty (k

N)

Fitting line

106

105

104

103

102

101

100

Measured Kd (GNm)

(b)






0 10 20 30 400

2

4

6

8


Coe

ffici

ent 120572



0 2000 4000 6000 8000 10000 120000

5000

10000

15000

20000


Q = P

Estim

ated

bea

ring

capa

city

Q (k

N)

Design load P (kN)




5 Conclusions


5 10 15 20 25 300

3

6

9

12

15



Kd

(GN

m)















0

4

8

12

16

20

24

28

I

H

G

F

E

D

C

BSam

ple n

umbe

r

QP

lt085 085sim1 1sim115 gt115

A


(a) 119876119875 lt 085 (b) 085 lt 119876119875 lt 1

(c) 1 lt 119876119875 lt 115 (d) 119876119875 gt 115


Acknowledgment


References





















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










0 400300200100

0

0 8070605040302010Frequency (Hz)

Pile 1Pile 2

Frequency (Hz)

Kd

(Nm

)

Kd

(Nm

)

1

2

3

4

5times1011

minus1

minus40

minus20

40times1010

20

00


2 4 6 8 10 12 14 16 18 20

Allo

wab

le b

earin

g ca

paci

ty (k

N)

106

105

104

103

102

101

100

Measured Kd (GNm)

(a)

2 4 6 8 10 12 14 16 18 20

Allo

wab

le b

earin

g ca

paci

ty (k

N)

Fitting line

106

105

104

103

102

101

100

Measured Kd (GNm)

(b)






0 10 20 30 400

2

4

6

8


Coe

ffici

ent 120572



0 2000 4000 6000 8000 10000 120000

5000

10000

15000

20000


Q = P

Estim

ated

bea

ring

capa

city

Q (k

N)

Design load P (kN)




5 Conclusions


5 10 15 20 25 300

3

6

9

12

15



Kd

(GN

m)















0

4

8

12

16

20

24

28

I

H

G

F

E

D

C

BSam

ple n

umbe

r

QP

lt085 085sim1 1sim115 gt115

A


(a) 119876119875 lt 085 (b) 085 lt 119876119875 lt 1

(c) 1 lt 119876119875 lt 115 (d) 119876119875 gt 115


Acknowledgment


References





















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










0 10 20 30 400

2

4

6

8


Coe

ffici

ent 120572



0 2000 4000 6000 8000 10000 120000

5000

10000

15000

20000


Q = P

Estim

ated

bea

ring

capa

city

Q (k

N)

Design load P (kN)




5 Conclusions


5 10 15 20 25 300

3

6

9

12

15



Kd

(GN

m)















0

4

8

12

16

20

24

28

I

H

G

F

E

D

C

BSam

ple n

umbe

r

QP

lt085 085sim1 1sim115 gt115

A


(a) 119876119875 lt 085 (b) 085 lt 119876119875 lt 1

(c) 1 lt 119876119875 lt 115 (d) 119876119875 gt 115


Acknowledgment


References





















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










0

4

8

12

16

20

24

28

I

H

G

F

E

D

C

BSam

ple n

umbe

r

QP

lt085 085sim1 1sim115 gt115

A


(a) 119876119875 lt 085 (b) 085 lt 119876119875 lt 1

(c) 1 lt 119876119875 lt 115 (d) 119876119875 gt 115


Acknowledgment


References





















RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation

























RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation









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