Thesis main part (cover board of exam declaration ackn ...

PILE LOAD CAPACITY USING STATIC AND DYNAMIC LOAD TEST

By

ANUP KUMAR HALDER

A thesis submitted to the Department of Civil Engineering,

Bangladesh University of Engineering and Technology,

Dhaka, in partial fulfillment of the degree of

MASTER OF SCIENCE IN CIVIL ENGINEERING (Geotechnical)

BANGLADESH UNIVERSITY OF ENGINEERING AND TECHNOLOGY

APRIL, 2016

CADIDIDATE'S DECLARATION

It is hereby declared lpl this thesis or any part of it has not been sub,mitted elsewhere for

the award ofany degree or diploma.

(Anup Kumar Halder)

111

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iv

ACKNOWLEDGEMENTS

The author is obliged to his supervisor Dr. Mehedi Ahmed Ansary, Professor,

Department of Civil Engineering, Bangladesh University of Engineering and Technology

(BUET), for his inspiration, encouragement, continuous guidance, important suggestions

throughout the various stages of this research. The author also expresses his profound

gratitude to Dr. Abdul Muqtadir, Professor and Head, Department of Civil Engineering,

BUET, Dhaka, for his valuable corrections and suggestions during writing of this thesis.

The author gratefully acknowledges the constructive criticisms and valuable suggestions

made by Dr. Abu Siddique, Professor, Department of Civil Engineering, BUET. Thanks

are due to Dr. Md. Abu Taiyab, Professor, Civil Engineering Department, DUET,

Gazipur for his review and comments.

Special thanks are also due to ‘Icon Engineers Services’ and ‘Prosoil’ for providing data

and technical assistance towards this thesis.

Last but not the least the author gratefully acknowledges the patience and encouragement

of his parents, spouse and daughter for supporting his endeavor of M. Sc. Engineering

study in BUET.

v

ABSTRACT

Piles are common for construction of deep foundation in Bangladesh. Confirming the pile

capacity is a job for a geotechnical engineer. From the soil investigation data, piles can be

designed but it need to be confirmed by static pile load test or dynamic pile load test. Generally,

static pile load test is used to estimate pile capacity whereas dynamic pile load test is a relatively

new method for the engineers of Bangladesh.

This study presents an evaluation of ultimate pile load capacity by static and dynamic load test

methods. To establish a comparison, a field experiment was conducted on two full scale driven

precast piles. Both piles were tested using dynamic and static load test. For dynamic load test pile

capacity was determined using CAPWAP (CAse Pile Wave Analysis Program). In case of static

load test pile capacity was calculated using Davission, Butler and Hoy, British standard and

BNBC (Bangladesh National Building Code) 1993 methods. The capacity of two test piles was

also calculated using soil investigation data applying BNBC-2015 (Draft version), AASHTO-

2002 method. For these two driven piles capacity calculations were also investigated following

driving equations. The relationship among capacity of static load test, dynamic load test,

predicted capacities (using BNBC-2015, BNBC SPT, AASHTO-2002, driving equations) were

compared and correlation values were obtained.

To generalize the study, ten cast-in-situ and fifteen precast test pile data were collected. In each

case, soil investigation report of the particular site, pile properties, CAPWAP capacity was

available for detailed study. From the collected data, it was found that predicted capacity of

precast driven piles using BNBC-2015 static bearing capacity has a very good co-relation with

CAPWAP capacity confirmed by dynamic load test. For BNBC-15 Static method, CAPWAP

capacity=1.10X BNBC 2015 Static capacity (r2=0.81).However, pile capacity calculated using

BNBC-2015 SPT method also showed good correlation compare with the CAPWAP capacity. In

this method CAPWAP capacity=1.06X BNBC 2015 SPT capacity (r2=0.77).

Similarly, cast-in-situ pile capacity matched fairly well with all the considered methods like:

BNBC-2015 static bearing capacity, BNBC-2015 SPT, AASHTO-2002 comparing with the

CAPWAP capacity. From this study three relations were established. They are CAPWAP

capacity=1.15X BNBC 2015 Static capacity (r2=0.81), CAPWAP capacity=1.04X BNBC 2015

SPT capacity (r2=0.89) and CAPWAP capacity=0.91X AASHTO-2002 capacity (r2=0.92).

Recommendation and conclusions were also made for piles of Bangladesh considering different

alternative methods.

vi

TABLE OF CONTENTS

Candidate's Declaration iii

Acknowledgements iv

Abstract v

Table of Contents vi

List of Tables ix

List of Figures x

Notations xii

CHAPTER 1: INTRODUCTION 1

1.1 General 1

1.2 Background of the Study 1

1.3 Objectives of the Study 2

1.4 Organization of the Thesis 3

CHAPTER 2: LITERATURE REVIEW 4

2.1 Introduction 4

2.2 Ultimate Pile Capacity 4

2.3 Driven Pile Capacity Using Static Formulae 5

2.3.1 Cohesive soil 5

2.3.2 Cohesion-less soil 6

2.4 Driven Pile Capacity Using SPT 7



2.5 Bored Pile Capacity Using Static Formulae 8



2.6 Bored Pile Capacity Using SPT Values 11


vii


2.7 Bored Pile Capacity Based on AASHTO 2002 12

2.8 Pile Capacity During Driving 15

2.8.1 Engineering News formula 15

2.8.2 Gates formula 16

2.8.3 Janbu formula 16

2.9 Pile Capacity by Static Load Test 17

2.9.1 Load test evaluation methods for axial compressive load 18

2.10 Dynamic Analysis by Wave Equation 20

2.10.1 The wave equation 20

2.10.2 Smith’s idealization 21

2.10.3 Pile modes-internal spring 23

2.10.4 Soil model external springs 23

2.10.5 Basic equation 25

2.10.6 Values of soil parameters 26

2.11 Dynamic Load Test 28

2.11.1 Test method 28

2.12 Methods Of Interpretation For Dynamic Load Test 29

2.12.1 CASE method 29

2.12.2 CAPWAP method 30

2.12.3 Summary 31

CHAPTER 3: INSTRUMENTATION AND TEST PROGRAM 32

3.1 General 32

3.2 Capacity Estimation 32

3.3 Pile Load Tests 36

3.4 Pile Driving and Driving Record 36

3.5 Dynamic Load Test Arrangement 37

3.6 Static Load Test Arrangement 40

viii

3.6.1 Loading sequnce 42

3.7 Data Collection 44

3.8 Summary 46

CHAPTER 4: RESULTS AND DISCUSSIONS 47

4.1 General 47

4.2 Pile Capacity of Precast Piles Using Driving Equations 47

4.3 Pile Capacity Using PDA Test Results 47

4.4 CAPWAP Analysis 50

4.5 Pile Capacity From Pile Load Tes 53

4.6 Pile Capacity Summary 55

4.7 Comparison with Collected Data for Cast-In-Situ Piles 57

4.8 Summary 59

CHAPTER 5: CONCLUSIONS 61

5.1 General 61

5.2 Concluding Remarks 61

5.3 Recommendations 62

References 63

APPENDIX A: PILE DRIVING RECORDS OF TP-1 AND TP-2 67

APPENDIX B: CAPACITY CALCULATION USING DRIVING EQUATIONS 72

APPENDIX C: CAPACITY CALCULATION OF PRECAST PILES 76

APPENDIX D: CAPACITY CALCULATION OF BORED PILES 107

ix

LIST OF TABLES

Table 2.1 Typical ϕs/ϕ and K/Ko values for the design of drilled Shaft 11

Table 2.2 Recommended values of α and fsi for estimation of drilled shaft side resistance in cohesive soil, after Reese and O’Neill (1988)

13

Table 2.3 Recommended values of unit end bearing for cohesion-less soil (Reese and O’Neill, 1988)

15

Table 2.4 Empirical values of Q,J and percent side adhesion 27

Table 2.5 Range of CASE damping values for different types of soil 30

Table 3.1 Load testing program for test piles 36

Table 3.2 Static load test program 40

Table 3.3 Typical loading sequence arrangement for pile load test 43

Table 3.4 Data summary for precast pile 45

Table 3.5 Data summary for cast-in-situ pile 46

Table 4.1 Beta value for pile integrity (Rausche and Goble, 1979) 48

Table 4.2 Capacity of piles using PDA 49

Table 4.3 Summary of dynamic test 52

Table 4.4 Test result summary 54

Table 4.5 Pile capacities from driving formulas 55

x

LIST OF FIGURES

Figure 2.1 Bearing capacity factor Nq for deep foundation (After Tomlinson, 1986)

7

Figure 2.2 Adhesion factor α for drilled shaft (after Kulhawy and Jackson, 1989)

9

Figure 2.3 Identification of Portions of drilled shafts neglected for estimation of drilled shaft side resistance in cohesive soil, after Reese and O’ neill (1988)

13

Figure 2.4 Smith’s spring model (Smith, 1960) 22

Figure 2.5 Load deformation relationships for internal springs 23

Figure 2.6 Load-deformation relationship of soil (after Lowery et al, 1969) 24

Figure 3.1 Flow diagram of the working process 33

Figure 3.2 Borehole log BH-1 34

Figure 3.3 Borehole log BH-2 35

Figure 3.4 Casting of pile at site for construction 36

Figure 3.5 Pile driving using drop hammer 37

Figure 3.6 Strain transducers and accelerometer bolted on the concrete piles 39

Figure 3.7 Pile driving analyser 39

Figure 3.8 Dynamic test arrangement for TP-1 40

Figure 3.9 Dynamic test arrangement for TP-2 40

Figure 3.10 Schematic diagram of typical arrangement of applying load in an axial compressive test

41

Figure 3.11 Schematic diagram of data collection for precast and cast in situ piles

44

Figure 4.1 Force and velocity record for TP-1 49

Figure 4.2 Force and velocity record for TP-2 50

Figure 4.3 CAPWAP Iteration force matched graph for TP-1 51

Figure 4.4 CAPWAP Iteration force matched graph for TP-2 51

Figure 4.5 Load settlement graph for Pile load test TP-1 52

xi

Figure 4.6 Load settlement graph for pile load test TP-1 53

Figure 4.7 Load settlement graph for pile load test TP-2 54

Figure 4.8 Correlation between CAPWAP and BNBC 2015 (static bearing) pile capacity for precast pile

56

Figure 4.9 Correlation between CAPWAP and BNBC 2015 (SPT) and pile capacity for precast pile

57

Figure 4.10 Correlation between CAPWAP and BNBC-2015 (static bearing) capacity

58

Figure 4.11 Correlation between CAPWAP capacity and BNBC-2015 SPT capacity for cast-in-situ pile

59

Figure 4.12 Correlation between CAPWAP and AASHTO-2002 pile capacity for cast-in-situ piles

59

xii

NOTATIONS

A = Cross sectional area of pile

A = End bearing area of pile

A = Skin friction area (perimeter area) of pile

B,D = Diameter or width of pile

D = Diameter of pile at base

D = Critical depth of soil layer

E = Modulus of elasticity of pile material

E = Modulus of elasticity of soil

FS = Factor of safety

H = Layer thickness

K = Coefficient of earth pressure

K = Coefficient of earth pressure at rest

L = Length of pile

N = Standard penetration test value (SPT)

N = Corrected SPT value for field procedures

N = Average SPT N value

(N ) = Corrected SPT value for overburden pressure (for sandy soil)

N , N , N = Bearing capacity factors

OCR = Over consolidation ratio

Q = Allowable load

Q = End bearing at the base or tip of the pile

Q = Load transferred to the soil at pile tip level

Q = Skin friction or shaft friction or side shear

Q = Ultimate bearing/load carrying capacity

W = Weight of the pile

c = Apparent cohesion of soil

c = Un-drained cohesion of soil

f = End bearing resistance on unit tip area of pile

f = Skin frictional resistance on unit surface area of pile

g = Gravitational acceleration

q = Unconfined compressive strength

xiii

s = Un-drained shear strength; same as c

z = Depth

∆z = Thickness of any (i ) layer

α = Adhesion factor

β = Friction factor due to overburden

γ, γ = Unit weight of the soil

γ = Unit weight of water

μ = Poisson’s ratio of soil

σ = Initial effective stress at mid-point of a soil layer

σ = Increase in effective stress at mid-point of a soil layer due to increase in stress

σ = Reference stress (100 kPa) for computation of pile settlement

σ = The total vertical stress

σ = Effective vertical stress

σ = Effective vertical stress; same as σ

ϕ = Apparent angle of internal fiction

ϕ = Effective/drained angle of internal fiction

1

CHAPTER 1

INTRODUCTION

1.1 General

Piles are conventionally the best possible solution in case of soft soil for transferring

structural load to the harder layers of soil strata. Generally, high safety factors are used

to get assurance in pile design as there are many uncertainties arise from concreting for

cast-in-situ piles and driving for precast piles. Pile load test shall be conducted to verify

design capacity and thus ensure economical design.

Generally, static pile load test provides best method for determining bearing capacity of

pile but it is time consuming and expensive. Under this condition dynamic load test can

be considered as an alternative of static load test. Since, the usage of static load test is

very common and dynamic test is newly adopted in our country, comparison between

the two tests is attempted in this project.

1.2 Background of the Study

Soft soil is very common in the southern part of Bangladesh which is not suitable for

construction of shallow foundation. Pile foundation provides the best possible solution

to transfer load to the deeper harder layers of soil. In Bangladesh, the traditional

practice is to construct cast in situ concrete piles. However, precast piles are also used

in large numbers because of their various advantages over cast in situ piles; like: high

quality of construction, idea of capacity during driving etc.

Estimating pile capacity accurately is a difficult job even for the experienced

geotechnical engineer. There are many conventional methods for calculating pile

capacity but selection of each requires knowledge of soil properties as well as the

limitation or applicability of any method in a regional boundary. Traditionally, pile

capacity can be evaluated by using bore log of subsoil investigation report (Bowles,

1997) later it need to be confirmed by static load test.

In the design process, ‘test piles’ need to be tested using static pile load test before

fixing the final length, capacity and cross section. It is a time consuming and expensive

test for a construction project which requires extensive supervision. Moreover, the test

has some problems like: transferring load to the pile due to frictional errors (Hoque et.

2

al, 1999). In addition, manual data collection system introduces human error

possibilities. In this circumstances, a suitable alternative to static load test or cross

checking options were necessary for foundation engineers.

Researchers in Bangladesh showed keen interest regarding pile related issues. Khan

(2002) has attempted to correlate ultimate pile capacity and settlement from static test

data of twenty one precast RCC piles and twenty five RCC cast in situ piles. Similarly,

Rahman (2008) verified axial load capacity of cast in situ piles with static load test in

stiff Dhaka clay. Prediction of load deformation behavior of axially loaded piles in sand

was also done by Morshed (1991). Rahman (2014) has studied performance of eight

methods based on cone penetration test (CPT) for predicting the ultimate load carrying

capacity of square precast RC concrete piles. Until now, no research work was done

considering application of dynamic load test in Bangladesh.

Pile dynamic analysis using wave equation requires very basic driving system, pile

parameters and few standard soil properties. It uses measurement of strain and

acceleration near the pile head when pile drives or restrikes with a pile driving hammer.

These dynamic measurements can be used to evaluate performance of pile driving

system, pile installation stress, pile integrity as well as static capacity. Test data can be

further evaluated using signal matching techniques to determine relative soil resistance

distribution and dynamic properties for use in wave equation analysis. A Pile Driving

Analyzer (PDA) receives data during driving or restrike of pile through two pair of

strain and acceleration transducers attached near the pile head. PDA instantly can

determine pile stress, integrity, approximate static pile capacity and energy

transmission to the pile. PDA data can be used for CAse Pile Wave Analysis Program

(CAPWAP) analysis to determine refine static capacity, soil resistance distribution, soil

quake and damping parameters for wave equation input (Rausche et al, 2000). Dynamic

analysis need to check with static load test method simultaneously to ensure

applicability. A firm relationship with static and dynamic load test method need to

establish before using dynamic load test in the context of our country which is truly

absent until now.

1.3 Objectives of the Study

The objectives of the study are as follows:

3

i. To determine the ultimate compressive pile load capacity of precast driven pile

using Pile Dynamic Analyzer (PDA).

ii. To determine the ultimate compressive pile load capacity of precast pile using

soil test data mainly, Standard Penetration Test (SPT) value and pile driving

records.

iii. To determine the ultimate compressive pile capacity using Static Pile load test.

iv. To compare the pile load capacity obtained from different methods.

1.4 Organization of the Thesis

The thesis is composed of five chapters. In Chapter One, background and objectives of

the research is described. Chapter two contains the literature review where methods for

calculating pile capacity using soil parameter are discussed. In this chapter pile load test

both static and dynamic method along with dynamic formulas, wave equation, dynamic

soil response, computational tools for wave equation, dynamic loading test etc. is also

described here.

Chapter three focus on the testing arrangement and program for data collections at site

and laboratory. Chapter four contains results and discussion of collected data. The final

Chapter contains conclusions and recommendations for further research.

4

CHAPTER 2

LITERATURE REVIEW

2.1 Introduction

There are numerous equations available for evaluating the pile capacity for engineering

professionals (Bowles, 1997). Based on soil classification, different equations have

been evolved to predict the ultimate capacity of pile. For precast pile, capacity

calculation is based on observing pile penetration per blow during driving. After the

pile is installed in the desired soil strata, capacity can be ascertain by applying pile load

test both static and dynamic. So, there is a scope to study pile capacity and compare or

correlate among the methods.

2.2 Ultimate Pile Capacity

The ultimate load capacity, Q , of a pile consists of two parts. One part is due to

friction called skin friction or shaft friction or side shear, Q and the other is due to end

bearing at the base or tip of the pile, Q The ultimate axial capacity (Q ) of piles shall

be determined in accordance with the following for compression loading.

Q = Q + Q − W (2.1)

Where, W is the weight of the pile. The skin friction, Q and end bearing Q can be

calculated as:

Q = A f (2.2)

Q = A f (2.3)

Where, A = skin friction area (perimeter area) of the pile = Perimeter × Length

f = skin frictional resistance on unit surface area of pile that depends on soil

properties and loading conditions (drained or un-drained)

A = end bearing area of the pile = Cross-sectional area of pile tip (bottom)

f = end bearing resistance on unit tip area of pile, that depends on soil

properties to a depth of 2B (B is the diameter for a circular pile section or

length of sides for a square pile section) from the pile tip and loading

conditions (drained or un- drained)

5

For a layered soil system containing n number of layers, end bearing resistance can be

calculated considering soil properties of the layer at which the pile rests, and the skin

friction resistance considers all the penetrating layers calculated as:

Q = ∑ ∆Z × (Perimeter) × (f ) (2.4)

Where, ∆Z represents the thickness of any i layer and (Perimeter) is the perimeter

of the pile in that layer. The manner in which skin friction is transferred to the adjacent

soil depends on the soil type.

2.3 Driven Pile Capacity using Static Formulae

2.3.1 Cohesive soil

The ultimate axial capacity of driven piles in cohesive soil may be calculated from

static formula, given by Equations 2.2, 2.3 and 2.4, using a total stress method for un-

drained loading conditions, or an effective stress method for drained loading

conditions. Appropriate values of adhesion factor (α) and coefficient of horizontal soil

stress (k ) for cohesive soils that are consistent with soil condition and pile installation

procedure may be used. The following α-method is used for calculating skin friction:

The α-method that is based on total stress analysis and is normally used to estimate the

short term load capacity of piles embedded in fine grained soils. In this method, a

coefficient α is used to relate the un-drained shear strength c or s to the adhesive

stress (f ) along the pile shaft. To calculate the skin friction of pile in cohesive soil,

Tomlinson (1971) proposed this method.

Q = αc A (2.5)

American Petroleum Institute (API, 1984) provides the following values to find the

skin friction in clay soils.

α = 1.0 for clays with c ≤ 25 kN/m2

α = 0.5 for clays with c ≥ 70 kN/m2

α = 1 − for clays with 25 kN/m2 < c < 70 kN/m2

The end bearing in such a case is found by analogy with shallow foundations and is

expressed by Mayerhof (1976) as:

Q = (c ) (N ) A (2.6)

6

N is a bearing capacity factor and for deep foundation the value is usually 9. c is the

undrained shear strength of soil at the base of the pile. The suffix b’s are indicatives of

base of pile. The general equation for N is, however, as follows (Skempton, 1951).

N = 6 1 + 0.2 ≤ 9 (2.7)

D represents the diameter of the pile at base and L is the total length of pile. The skin

friction value, f = (c ) (N ) should not exceed 4.0 Mpa (Engeling and Reese,

1974).

2.3.2 Cohesion-less soil

The 𝛽 -method is based on an effective stress analysis and is used to determine both the

short term and long term pile load capacities. Burland (1973) developed this method of

obtaining skin friction from effective stress on the shaft of pile. The friction along the

pile shaft is found using Coulomb’s friction law, where the friction stress is given

by f = μσ = σ tanϕ . The lateral effective stress, σ is proportional to vertical

effective stress, σ by a co-efficient, K. As such,

f = Kσ tanϕ = βσ (2.8)

Where,

β = Ktanϕ = K tanϕ = (1 − sinϕ′)√OCR (2.9)

ϕ is the effective angle of internal friction of soil and OCR is the over-consolidation

ratio. For normally consolidated clay, β varies from 0.25 to 0.29. The value of β

decreases for a very long pile, as such a correction factor is used (Kaniraj, 1988)

Correction factor for β = log ≥ 0.5 (2.10)

The end bearing capacity is calculated by analogy with the bearing capacity of shallow

footings and is determined from:

f = (σ ) N (2.11)

Where, N is a bearing capacity factor that depends on angle of internal friction ϕ of

the soil at the base of the pile, as presented in Figure 2.1. Subscript “b” designates the

parameters at the base soil.

7

Figure 2.1: Bearing capacity factor Nq for deep foundation (After Tomlinson, 1986)

2.4 Driven Pile Capacity Using SPT

2.4.1 Cohesive soil

Standard Penetration Test N-value is a measure of consistency of clay soil and

indirectly the measure of cohesion. The skin friction of pile can thus be estimated from

N-value. The following relation may be used for preliminary design of ultimate

capacity of concrete piles in clay soil. According to Mayerhof (1976)

For skin friction the relationship is as under.

f = 1.8N (in kPa) ≤ 70 kPa (2.12)

For end bearing, the relationship is as under.

f = 45N (in kPa) ≤ 4000 kPa (2.13)

Where, N is the average N-value over the pile shaft length and N is the N-value in

the vicinity of pile tip.

8

2.4.2 Cohesion-less soil

Standard Penetration Test N-value is a measure of relative density hence angles of

internal friction of cohesion less soil. The skin friction of pile can thus be estimated

from N-value. The following relation may be used for ultimate capacity of concrete

piles in cohesion less soil and non-plastic silt.

For skin friction the relationship is as under (Mayerhof, 1976)

For sand:

f = 2N (in kPa) ≤ 60 kPa (2.14)

For non-plastic silt:

f = 1.7N (in kPa) ≤ 60 kPa (2.15)

For end bearing, the relationship is as under (Mayerhof, 1976)

For sand:

f = 40N (in kPa) ≤ 400N and ≤ 11000 kPa (2.16)


f = 30N (in kPa) ≤ 300N and ≤ 11000 kPa (2.17)



2.5 Bored Pile Capacity Using Static Formulae

2.5.1 Cohesive soil

Skin friction resistance in cohesive soil may be determined using either the α-method or

the β-method as described in the relevant section of driven piles. However, for clay

soil, α-method has wide been used by the engineers. This method gives:

f = αs (2.18)

Where,

f = Skin friction

s = undrained shear strength of soil along the shaft

9

α = adhesion factor =0.55 for undrained shear strength ≤ 190 kPa (4000 psf)

For higher values of s the value of α may be taken from Figure 2.2 as obtained from

test data of previous investigators.

Figure 2.2: Adhesion factor α for drilled shaft (after Kulhawy and Jackson, 1989)

The skin friction resistance should be ignored in the upper 1.5 m of the shaft and along

the bottom one diameter of straight shafts because of interaction with the end bearing.

If end bearing is ignored for some reasons, the skin friction along the bottom one

diameter may be considered. For belled shaft, skin friction along the surface of the bell

and along the shaft for a distance of one shaft diameter above the top of bell should be

ignored. For end bearing of cohesive soil, the following relations given by Equations

2.19 and 2.20 are recommended.

f = N S ≤ 4000 kPa (2.19)

Where, N = 6 1 + 0.2 ≤ 9 (2.20)

10

Where,

f = End bearing stress

S = undrained shear strength of soil along the shaft

N = Bearing capacity factor

L = Length of the pile (Depth to the bottom of the shaft)

D = Diameter of the shaft base

2.5.2 Cohesion less soil

Skin friction resistance in cohesion less soil is usually determined using the β-method.

The relevant equation is reproduced again:

f = βσ (2.21)

β = Ktanϕ (2.22)

Where,

f = Skin friction

σ = Effective vertical stress at mid-point of soil layer

K = Coefficient of lateral earth pressure

ϕ = Soil shaft interface friction angle

The values of K and ϕ can be obtained from the chart of Tables 2.1, from the soil

friction angle, ϕ and preconstruction coefficient of lateral earth pressure K . However,

K is very difficult to determine. An alternative is to compute β directly using the

following empirical relation.

β = 1.5 − 0.135 (2.23)

Where,

Br = Reference width=1 ft = 0.3 m = 12 inch = 300 mm

z = Depth from the ground surface to the mid-point of the strata

11

Table 2.1: Typical 𝛟𝐬/𝛟 and 𝐊/𝐊𝐨 values for the design of drilled shaft

Construction method

𝛟𝐬 /𝛟

Construction method

𝐊/𝐊𝐨

Open hole or temporary casing

1.0 Dry construction with minimal side wall disturbance and prompt concreting

1

Slurry method – minimal slurry cake

1.0 Slurry construction – good workmanship

1

Slurry method – heavy slurry cake

0.8 Slurry construction – poor workmanship

2/3

Permanent casing 0.7 Casing under water 5/6

2.6 Bored Pile Capacity Using SPT Values

2.6.1 Cohesive soil

The following relations may be used for preliminary design of ultimate capacity of

concrete bored piles in clay soils. According to Mayerhof (1976)

For skin friction the relationship is as under.

f = 1.2N (in kPa) ≤ 70 kPa (2.24)

For end bearing, the relationship is as under.

f = 25N (in kPa) ≤ 4000 kPa (2.25)



2.6.2 Cohesionless soil

Standard Penetration Test N-value is a measure of relative density hence angle of

internal friction of cohesion less soil. The skin friction of pile can thus be estimated

from N-value. The following relation may be used for ultimate capacity of concrete

piles in cohesion less soil and non-plastic silt.

For skin friction the relationship is as under (Mayerhof, 1976).

For sand:

f = 1.0 N (in kPa) ≤ 60 kPa (2.26)

12


f = 0.9N (in kPa) ≤ 60 kPa (2.27)

For end bearing, the relationship is as under (Mayerhof, 1976).

For sand:

f = 15N (in kPa) ≤ 150N and ≤ 4000 kPa (2.28)


f = 10N (in kPa) ≤ 100N and ≤ 4000 kPa (2.29)



2.7 Bored Pile Capacity Based on AASHTO 2002

The ultimate axial capacity (Qult) of drilled shafts shall be determined in accordance

with the following for compression:

Qult=Qs+QT -W (2.30)

Shaft in cohesive soils may be designed by total and effective stress methods of

analysis, for un-drained and drained loading conditions, respectively. Shafts in

cohesion-less soil shall be designed by effective stress methods of analysis for drained

loading conditions.

Side resistance in cohesive soil

For shafts in cohesive soil located under un-drained loading conditions, the ultimate

side resistance may be estimated using the following equation:

Qs=πB ∑ αi Sui Δzi (2.31)

The ultimate unit load transfer in side resistance at any depth fsi is equal to the product

of αi and Sui. Refer to Table 2.2 for guidance regarding selection of αi and limiting

values of fsi for excavated dry in open or cased holes in cohesive soil after Reese and

O’neill (1988). Environmental long term loading or construction factor may dictate that

a depth greater than five feet should be ignored in estimating QS. Refer to Figure 2.3 for

identification of portions of drilled shaft not considered in contributing to the complete

13

value of QS. For shaft in cohesive soil under drained loading conditions may be

determined using the procedure in the next article.

Where time dependent changes in soil shear strength may occur (e.g., swelling of

expansive clay or down drag from a consolidating clay), effective stress method should

be used to compute QS in the zone where such changes may occur.

Table 2.2: Recommended values of α and fsi for estimation of drilled shaft side

resistance in cohesive soil, after Reese and O’Neill (1988)

Location of drilled shaft Value of α

Limiting value of load transfer, fsi

(ksf)

From ground surface to depth along drilled shaft of 5ft*

0 -

Bottom 1 diameter of the drilled shaft or 1 stem diameter above the top of the bell (if skin friction is being used)

0 -

All other points along the sides of the drilled shaft 0.55 5.5

*The depth of 5 ft may need adjustment if the drilled shaft is installed in expansive clay or if there is substantial ground line deflection from lateral loading

Figure 2.3: Identification of Portions of drilled shafts neglected for estimation of drilled shaft side resistance in cohesive soil, after Reese and O’ neill (1988)

14

Side resistance in cohesion-less soil

For shafts in cohesion-less soil or for effective stress analysis of shafts in cohesive soils

under drained loading conditions, the ultimate side resistance of axially loaded drilled

shafts may be estimated using the following equation:

QS=πB∑ γi'ziβiΔzi (2.32)

The βi may be determined using the following:

βi=1.5-0.135√zi ; 1.2> βi>0.25 (2.33)

The value of γi' should be determined from measurements from undisturbed sample

along the length of the shaft or from empirical correlations with SPT or other in-situ

test methods. The ultimate unit load transfer in side resistance at any depth, fsi, is equal

to the product of βi and σvi. The limiting value of fsi for shafts in cohesion-less soil is 4

ksf.

Tip resistance in cohesive soil

For axially loaded shafts in cohesive soil subjected to un-drained loading conditions,

the ultimate tip resistance of drilled shafts may be estimated using the following:

QT=qTAT=Nc Sut AT (2.34)

qT=Unit end bearing

AT=Cross section area of pile

Sut=Un-drained shear strength

Values of bearing capacity factor Nc may be determined using the following:

Nc=6.0[1+0.2(D/Bi)];Nc≤9 (2.35)

The limiting value of unit end bearing (qT=NcSut) is 80ksf.

The value of Sult should be determined from the results of in-situ and or laboratory

testing of un-drained samples obtained within a depth of 2B below the tip of the shaft.

If soil within 2B of the tip is of soft consistency the value of Nc should be reduced by

one-third.

Tip resistance in cohesion-less soil

15

There is a tendency for the sand to loosen slightly at the bottom of excavation due to

relief of stress. Some densification of sand occurs below the base of a drilled shaft as

settlement occurs. The load-settlement curve that have been obtained by experiment for

the base of drilled shafts are consistent with the above concepts. The load continued to

increase for some of the tests to a settlement of more than 15 percent of the diameter of

the base. Such a large amount of settlement could not be tolerated for most structures;

therefore, it was decided to limit the values of end bearing for drilled shafts in granular

soil to that which could occur at a downward movement of the base of 5 percent of the

diameter of the base.

Table 2.3: Recommended values of unit end bearing for cohesion-less soil (Reese

and O’Neill, 1988)

Range of value of NSPT (Uncorrected) Values of qb (Tsf)

0 to 75 0.60 N

Above 75 45

2.8 Pile Capacity during Driving

It has been observed that a pile exerting greater resistance against driving can sustain

greater load. A number of formulae have been evolved to determine the load carrying

capacity based on the principle that the energy supplied to the pile is utilized in useful

work done in driving the pile and in other loses. These formulae are known as

‘Dynamic formulae’.

The Engineering News formula is generally recognized to be one of the most popular

dynamic formula (Agerschou, 1962). Chellis (1961) list more than 30 different

formulae in his text book. Despite of their obvious deficiencies and unreliability the

pile formulae enjoy a great popularity among practicing engineers because of the use of

these formulae reduces the design of pile foundations to a very simple procedure.

2.8.1 Engineering News formula

This formula was published by Wellington in Engineering News in 1888 and it was

called Engineering News Record Formula (ENR). This is expressed as follows,

Pu= (2.36)

16

Pu =Ultimate capacity of pile

e =Hammer efficiency

W =Weight of ram

h=height of all of ram

s=amount of point penetration per blow

2.8.2 Gates formula

This method was the results of a research performed by Gates (1957). The basic

assumption is that the resistance is directly proportional to the squared root of the net

hammer energy. The relationship is presented by

P =a e E (b − log ) (2.37)

P = Ultimate pile capacity (kN)

Hammer efficiency, e =0.75 for drop hammer

Manufactures hammer energy rating E =kN.m

s= Point penetration per blow-set

a=104.5

b=2.4

A suggested safety factor to be used is 3.

In this formula, the following assumptions were made:

a) Hammer and pile may be treated as impinging particles

b) Hammer gives up its entire energy on impact.

c) On impact the resistance increases in an elastic manner as the pile is displaced,

remains constant for further displacement and then falls to zero in an elastic manner as

the pile rebounds.

2.8.3 Janbu formula

The Janbu formula as mentioned by Olson et al (1967). Pile resistance as measured

during driving using this method shall be taken as

17

P =

(2.38)

Wr =Weight of ram

Wp =Weight of pile

s=Pile set

E=Modulus of elasticity

e =Hammer efficiency

Eh=Manufactures hammer energy rating

L=Pile length

Cd=0.75+0.15 (2.39)

ku=Cd 1 + 1 + (2.40)

λ=

It also based on some assumptions such as:

a) There is frictional or other loss in the hammer system so that energy actually applied

at impact is less than energy delivered.

b) There is loss due to elastic compression of the pile.

c) There is loss due to impact.

Recommended factor of safety is 3 to 6.

2.9 Pile Capacity by Static Load Test

Static load tests relied upon an accurate measure of a pile’s ultimate resistance.

Ultimate resistance is the maximum resistance mobilized by the positive shaft

resistance and toe bearing in the soil. Static load testing involves loading the pile

statically by placing increments of load and recording settlements as the load is applied

following ASTM D1143. As the pile resistance may set up (resistance increased with

time) or relax (resistance decrease with time), static load tests are often performed after

some wait period so that equilibrium conditions are re-established .Two principal types

18

of test may be used for compression loading on piles - the constant rate of penetration

(CRP) test and the maintained load (ML) test.

Maintained load (ML) test will be used in this study. In the ML test the load is

increased in stages to 1.5 times or twice the working load with time settlement curve

recorded at each stage of loading and unloading. The general procedure is to apply

static loads in increments of 25% of the anticipated design load. The ML test may also

be taken to failure by progressively increasing the load in stages. In the ML test, the

load test arrangements as specified in ASTM D1143 shall be followed. According to

ASTM D1143 each load increment is maintained until the rate of settlement is not

greater than 0.25 mm/hr or 2 hours is elapsed, whichever occurs first. After that the

next load increment is applied. This procedure is followed for all increments of load.

After the completion of loading if the test pile has not failed the total test load is

removed any time after twelve hours if the butt settlement over one hour period is not

greater than 0.25 mm otherwise the total test load is kept on the pile for 24 hours. After

the required holding time, the test load is removed in decrement of 25% of the total test

load with 1 hour between decrement. If failure occurs, jacking the pile is continued

until the settlement equals 15% of the pile diameter or diagonal dimension.

2.9.1 Load test evaluation methods for axial compressive load

A number of arbitrary or empirical methods are used to serve as criteria for determining

the allowable and ultimate load carrying capacity from pile load test. Some are based

on maximum permissible gross or net settlement as measured at the pile but while the

others are based on the performance of the pile during the progress of testing Chellis

(1961); Whitaker (1976); Poulos and Davis (1980); Fuller (1983). It is recommended to

evaluate the load carrying capacity of piles and drilled shaft using any of the following

methods along with the arbitrary methods:

(a) Davission Offset Limit

(b) British Standard Institution Criterion

(c) Indian Standard Criteria

(d) Butler-Hoy Criterion

(e) Brinch-Hansen 90% Criterion

19

The recommended criteria to be used for evaluating the ultimate and allowable load

carrying capacity of piles and drilled shaft are summarized below.

(a) A very useful method of computing the ultimate failure load has been reported by

Davisson (1972). This method is based on offset method that defines the failure

load. The elastic shortening of the pile, considered as point bearing, free standing

column, is computed and plotted on the load-settlement curve, with the elastic

shortening line passing through the origin. The slope of the elastic shortening line

is 20o. An offset line is drawn parallel to the elastic line. The offset is usually 0.15

inch plus a quake factor, which is a function of pile tip diameter. For normal size

piles, this factor is usually taken as 0.1D inch, where D is the diameter of pile in

foot. The intersection of offset line with gross load-settlement curve determines the

arbitrary ultimate failure load. Davisson method is too restrictive for drilled piles,

unless the resistance is primarily friction. This method is recommended for driven

precast piles.

(b) Terzaghi (1942) reported that the ultimate load capacity of a pile may be considered

as that load which causes a settlement equal to 10% of the pile diameter. However,

this criterion is limited to a case where no definite failure point or trend is indicated

by the load-settlement curves. This criterion has been incorporated in BS 8004

“Code of Practice for Foundations” which recommends that the ultimate load

capacity of pile should be that which causes the pile to settle a depth of 10% of pile

width or diameter.

(c) The allowable load capacity of pile should be 50% of the final load, which causes

the pile to settle a depth of 10% of pile width or diameter BS 8004.

(d) Ultimate load capacity of pile is smaller of the following two IS: 2911 Part-4:

(i) Load corresponding to a settlement equal to 10% of the pile diameter in the case

of normal uniform diameter pile or 7.5% of base diameter in case of under-

reamed or large diameter cast in-situ pile.

(ii) Load corresponding to a settlement of 12 mm.

(e) Allowable load capacity of pile is smaller of the following IS: 2911 Part-4:

(i) Two thirds of the final load at which the total settlement attains a value of 12

mm.

20

(ii) Half of the final load at which total settlement equal to 10% of the pile diameter

in the case of normal uniform diameter pile or 7.5% of base diameter in case of

under-reamed pile.

(f) Butler and Hoy (1977) states that the intersection of tangent at initial straight

portion of the load-settlement curve and the tangent at a slope point of 1.27 mm/ton

determines the arbitrary ultimate failure load.

(g) The Brinch Hansen (1963) proposed a definition for ultimate load capacity as that

load for which the settlement is twice the settlement under 90 percent of the full test

load.

(h) Where failure occurs, the ultimate load may be taken to calculate the allowable load

using a factor of safety of 2.0 to 2.5.

2.10 Dynamic Analysis by Wave Equation

Pile driving could not accurately be analyzed by rigid-body mechanics led to the

development of an analysis that utilizes wave theory. The wave equation analysis of

pile driving has eliminated many shortcomings related with dynamic formulae by

accurately simulating the hammer impacts and pile penetration process. The use of

wave equation was considered by Isaacs (1931) and Glanville et al (1938); but not until

the works of Smith (1960), that the methodology was fully developed.

2.10.1 The wave equation

The wave equation may be derived from consideration of the internal forces and motion

produced on a segment of a freely-suspended prismatic bar subject to and impact at one

end. The resulting equation is

= (2.41)

Where D=longitudinal displacement of a point of the bar from its original position

E=modulus of elasticity of bar

ρ=density of bar material

t=time

x=direction of longitudinal axis

21

For a pile, the resistance of the surrounding soil must also be considered and the

equation becomes

= (±)R (2.42)

Where R= soil-resistance term

This equation may be solved for the appropriate initial and boundary conditions, to

determine the relationship among displacement, time and position in the pile. From

which the stress variation in the pile may be determined.

2.10.2 Smith’s idealization

Pile driving analyses are generally accomplished by modeling 1-D wave propagation in

an elastic rod (pile). The methods routinely used are based on a lumped mass

discretization of the pile with simplified rheological models of pile-soil interaction

following the framework first proposed by Smith (1960). The Smith model simulates 1-

D wave propagation in the pile idealized as in Figure 2.4 and consists of-

1. A ram, to which an initial velocity is imparted by the pile driver.

2. A cap-block

3. A pile cap.

4. A cushion block (cushioning material).

5. The pile.

6. The supporting soil.

22

Figure 2.4: Smith’s spring model (Smith, 1960)

The ram, cap block, pile cap, cushion block, and pile are represented by appropriate

discrete weights and springs. The frictional resistance on the side of the pile is

represented by a system of springs and dashpots (Figure 2.4), while the point resistance

is represented by a single spring and dashpot. The characteristics of the components are

considered subsequently. If the actual situation differs from that shown in Figure 2.4

that is, if the cushion block is not used or if an anvil is placed between ram and cap

block – the idealization of the system can of course be modified.

23

2.10.3 Pile modes-internal spring

The ram, cap block, pile cap, and cushion block may be considered to consist of

internal springs, although the ram and pile cap can often be treated as rigid bodies. The

load, deformation behavior of these elements is most simply taken to be linear (Figure

2.5a) although the internal damping may also be consider (e.g., as shown in Figure

2.5b), for components such as the cap block and the cushion block.

a) No internal Damping pile elements b) Internal damping cap block and cushion block

Figure 2.5: Load deformation relationships for internal springs.

2.10.4 Soil model external springs

Smith’s model of the load-deformation characteristics of the soil, represented as

external springs, subjected to static loading, is shown in Figure 2.6.The path

OABCDEFG represents loading and unloading in side friction. For the point, only

compressive loading is considered and the loading and unloading path is OABCF. The

quantities defining this static behavior are Q and Ru where

Q = “quake”, the maximum soil deformation that may occur elastically

Ru= ultimate soil resistance

A load deformation diagram such as Figure 2.6 may be established separately for each

spring, so that

K (m)=( )

( ) (2.43)

24

Where K (m) is the spring constant during elastic deformation for external spring m.

(c) Equivalent rheological model of soil

Figure 2.6: Load-deformation relationship of soil (after Lowery et al, 1969)

To allow for the effects of dynamic loading during driving in increasing the

instantaneous resistance of the soil, the dynamic load-settlement behavior of the soil is

taken to be that shown in Figure 2.6b, which is pointed out by Lowery et al (1969),

corresponds to a Kelvin rheological model (Figure 2.6c). This dynamic behavior is

characterized by a further parameter J, the damping constant. The dashpot in the model

produces an additional resisting force proportional to the velocity of loading (V).

25

2.10.5 Basic equation

In solving the wave equation numerically, Equation 2.44 could be expressed in finite-

differential form for each element, and then the resulting equations, incorporating the

appropriate boundary conditions, could be solved simultaneously for each time-interval

considered. This method is the conventional method for solving such equations and has

been suggested by Soderberg (1962); it may also be applied to periodic dynamic

loading of the pile. However, it has been shown by Smith (1960) that the finite-

difference form of the wave equations and this form of expression of the wave equation

has been adopted for pile-driving analysis. The basic equations are as follows:

D(m,t)=D(m,t-1)+Δt V(m,t-1)………………………............................ ....(2.44)

C(m,t)=D(m,t)-D(m+1,t) …….………………………………… …… …(2.45)

F(m,t)=C(m,t)K(m)………………………………………… ……….… ..(2.46)

R(m,t)=[D(m,t)-D (m,t)][K (m)[1+J(m)V(m,t- 1)]……………………… ..(2.47)

V(m,t)=V(m,t-1)+[F(m-1,t)+W(m)-R(m,t)]( )

…………… …… .…. .(2.48)

Where,

m=element number

t= time

Δt = time interval

C(m,t)= compression of internal spring m at time t

D(m,t)= displacement of external spring m at time t

Dˊ(m,t)=plastic displacement of external spring m at time t

F(m,t)= force in internal spring m at time t

g= acceleration caused by gravity

J(m)= soil damping constant at element m

K(m)= spring constant for internal spring m

26

K (m)= spring constant for external spring m

R(m,t)= force exerted by external spring m on element m at time t

V(m,t)= velocity of element m at time t

W(m)= weight of element m

Equation 2.48 applies for elastic pile elements for which internal damping is ignored.

For elements such as the cap block and the cushion block, in which internal damping

should be considered, the following equation should be used instead of equation 2.48.

F(m,t)=( )

[ ( )]. C(m, t) −

[ ( )]− 1 . K(m). C(m, t)max………………..... (2.49)

Where e(m)=coefficient of restitution of internal spring m

C(m,t)max= temporary maximum value of C(m,t)

The above equation characterizes the path OABCDEO shown in the Figure 2.6b .For a

pile cap or cushion block, no tensile forces can exist and hence only this part of the

diagram applies. Intermittent unloading-loading is typified by path ABC, established by

control of C(m,t) max in equation: 2.46. The slope of the of lines AB, BC and DE

depends on the value of e(m).

Smith (1960) notes that Equation 2.47 produces no damping when D(m,t)-D (m,t)

becomes zero, and suggests anal ternate equation to be used after D(m,t) first becomes

equal to Q(m), where Q(m) is the “quake” for element m.

R(m,t)=[D(m,t)-D (m,t)].K (m)+J(m).Ru(m).V(m,t- 1)………… ………… ....(2.50)

Where Ru(m) is the ultimate static soil-resistance of element m.

Equation 2.44 to 2.48 are solved for each of the pile elements involved, m=1 to m=p

(point), for a succession of time intervals starting when the hammer [W(1)] travelling

with known velocity touches the first spring. The solution of these equations continues

until the permanent set or plastic displacement of the soil at the point D (p,t) is a

maximum.

2.10.6 Values of soil parameters

The soil parameters required for the wave-equation analysis are the ultimate soil

resistance, Ru; quake Q; and damping factor, J.

27

Ultimate soil resistance, Ru

Various values of Ru are input into the computer program and the corresponding

permanent set determine the relative proportions of shaft and base resistance. A

reasonable estimate of these proportions may be made by made by estimating the static

shaft and base resistance from the known or assumed soil properties. A somewhat

higher ultimate resistance for a given driving resistance is obtained if some shaft

resistance is considered, rather than only end-bearing. As rough guide where other

information is not available, value of the percentage of shaft resistance suggested by

Forhan and Reese (1964) are shown in Table 2.4.

Table 2.4: Empirical values of Q, J and percent side adhesion

Soil Q(in) J(p) (sec/ft) Side Adhesion

(% of Ru)

Coarse sand 0.10 0.15 35

Sand and gravel mixed 0.10 0.15 75-100

Fine sand 0.15 0.15 100

Sand and clay or loam, at least 50% of pile in sand

0.20 0.20 25

Silt and fine sand underlain by hard strata 0.20 0.20 40

Sand and gravel underlain by had strata 0.15 0.15 25

Quake

Values of Q have obtained empirically to date, and the single empirical values of Q for

all elements of the pile suggested by Forhand and Reese (1964) are shown in Table

2.4.It is however possible to derive values of Q theoretically from pile settlement

theory if the “elastic” soil parameters are known. On the basis of this theory, the value

of Q varies along the pile, with the value at the pile tip being greater than the values

along the shaft. Alternatively, Q could also be estimated from the soil-resistance curve

employed by Seed and Reese (1957) and Coyle and Reese(1966).

Damping factor, J

Empirical correlations between J and soil type obtained by Forehand and Reese (1964)

are shown in Table 2.4.The values in the Table are for the pile point [i.e., J (p)]. The

average value for the sides of the pile J(m) have been found to be less than J(p), and for

practical purposes, it has been suggested that

28

J(m)= J(p)………………………………… ………………………………… (2.51)

Where J(m)= Soil damping constant for sides of pile

J(p)= Soil damping constant for pile point

2.11 Dynamic Load Test

Various techniques for dynamic loading tests are now available. These tests are

relatively cheap and quick to carry out compared with static loading tests. Information

that can be obtained from a dynamic loading test includes:

(a) Static load capacity of the pile,

(b) Energy delivered by the pile driving hammer to the pile,

(c) Maximum driving compressive stresses (tensile stress should be omitted), and

(d) Location and extent of structural damage.

2.11.1 Test method

The dynamic loading test is generally carried out by driving a prefabricated pile or by

applying impact loading on a cast-in-place pile by a drop hammer. A standard

procedure for carrying out a dynamic loading test is given in ASTM 4945-00.The

equipment required for carrying out a dynamic pile loading test includes a driving

hammer, strain transducers and accelerometers, together with appropriate data

recording, processing and measuring equipment. The hammer should have a capacity

large enough to cause sufficient pile movement such that the resistance of the pile can

be fully mobilized. A guide tube assembly to ensure that the force is applied axially on

the pile should be used. The strain transducers contain resistance foil gauges in a full

bridge arrangement. The accelerometers consist of a quartz crystal which produces a

voltage linearly proportional to the acceleration. A pair of strain transducers and

accelerometers are fixed to opposite sides of the pile, either by drilling and bolting

directly to the pile or by welding mounting blocks, and positioned at least two

diameters or twice the length of the longest side of the pile section below the pile head

to ensure a reasonably uniform stress field at the measuring elevation. It should be

noted that change of cross-section of the pile due to connection may affect the

proportionality of the signals and hence the quality of the data. An electronic theodolite

29

may also be used to record the displacements of the pile head during driving (ASTM

D4945-00) .In the test, the strain and acceleration measured at the pile head for each

blow are recorded. The signals from the instruments are transmitted to a data recording,

filtering and displaying device to determine the variation of force and velocity with

time.

2.12 Methods of Interpretation for Dynamic Load Test

Two general types of analysis based on wave propagation theory, namely direct and

indirect methods are available. Direct methods of analysis apply to measurements

obtained directly from a (single) blow, whilst indirect methods of analysis are based on

signal matching carried out on results obtained from one or several blows. Examples of

direct methods of analysis include CASE, IMPEDANCE and TNO method, and

indirect methods include CAPWAP, TNOWAVE and SIMBAT. CASE and CAPWAP

analyses are used mainly for displacement piles, although in principle they can also be

applied to cast-in-place piles. SIMBAT has been developed primarily for cast-in place

piles, but it is equally applicable to displacement piles. In a typical analysis of dynamic

loading test, the penetration resistance is assumed to be comprised of two parts, namely

a static component, Rs, and a dynamic component, Rd.

Two methods of analysis are described below.

2.12.1 CASE method

This method assumes that the resistance of the soil is concentrated at the pile toe. In the

analysis, the dynamic component is given by:

Rd = jc Z vb ……………………………………………………………..(2.52)

Here jc = the CASE damping coefficient

Z = impedance =Ep Ap/cw

Ap = cross sectional area of the pile

Ep = Young's modulus of the pile

cw = wave speed through the pile

vb = velocity of pile tip

The appropriate jc is dependent on the type of soil at the pile toe and the actual pile

dimensions. A range of jc values appropriate to different soil types was proposed by

Rausche et al (1985) and has been further refined by Pile Dynamics Inc. (PDI, 1996).

30

Typical ranges of jc are given in Table 2.5 These represent the damping factors at pile

toe and are correlated with dynamic and static loading tests. In practice, jc values can

vary significantly, particularly in layered and complex ground conditions, causing

potential errors in pile capacity prediction. For large piling projects where CASE

method is to be used to ascertain the load-carrying capacity of piles, site-specific tests

can be conducted to determine the appropriate damping factors by correlating the

CASE results with static loading tests or results of CAPWAP analysis.

Table 2.5: Range of CASE damping values for different types of soil

Soil type at pile toe CASE damping

(Rausche et al, 1985)

Updated CASE damping

(PDI, 1996)

Clean sand 0.05 – 0.20 0.10 – 0.15

Silty sand, sand silt 0.15 – 0.30 0.15 – 0.25

Silt 0.20 – 0.45 0.25 – 0.40

Silty clay, clayey silt 0.40 – 0.70 0.40 – 0.70

Clay 0.60 – 1.10 0.70 or higher

2.12.2 CAPWAP method

In a CAPWAP (CAse Pile Wave Analysis Program) analysis, the soil is represented by

a series of elasto-plastic springs in parallel with a linear dashpot similar to that used in

the wave equation analysis proposed by Smith (1960). The soil can also be modeled as

a continuum when the pile is relatively short. CAPWAP measures the acceleration-time

data as the input boundary condition. The program computes a force versus time curve

which is compared with the recorded data. If there is a mismatch, the soil model is

adjusted. This iterative procedure is repeated until a satisfactory match is achieved

between the computed and measured force-time diagrams. The dynamic component of

penetration resistance is given by

Rd = js vp Rs …………………………………………………….... ........ (2.53)

Where js = Smith damping coefficient

vp = velocity of pile at each segment

Rs = static component of penetration resistance

Input parameters for the analysis include pile dimensions and properties, soil model

parameters including the static pile capacity, Smith damping coefficient, js and soil

quake (i.e. the amount of elastic deformation before yielding starts), and the signals

31

measured in the field. The output will be in the form of distribution of static unit shaft

resistance against depth and base response, together with the static load-settlement

relationship up to about 1.5times the working load. It should be noted that the analysis

does not model the onset of pile failure correctly and care should be exercised when

predicting deflections at loads close to the ultimate pile capacity.

Results of CAPWAP analysis also provide a check of the CASE method assumptions

since the ultimate load calculated from the CAPWAP analysis can be used to calculate

the CASE damping coefficient. Sound engineering judgment is required in determining

whether a satisfactory match has been achieved and whether the corresponding

combination of variables is realistic.

2.12.3 Summary

This chapter describes the methods to calculate the pile capacity. Two types of pile was

discussed both precast and cast-in-situ type. Later each pile type was discussed based

on the soil classification. In addition to that, pile capacity using driving formula was

mentioned. To ascertain the predicted pile capacity load test was discussed. Based on

the aforementioned literature the capacity of pile will be determined in this study.

32

CHAPTER 3

INSTRUMENTATION AND TEST PROGRAM

3.1 General

The study location is at a construction site in Tangail. First, a detailed subsoil

investigation was done, with the help of two bore holes namely BH-1 and BH-2 which

was approximately 5m apart. Based on subsoil investigation precast rectangular piles

were selected. In this site detailed study of two precast piles was carried out. In the

preliminary design phase pile section 12˝X12˝ (300X300 mm2) and length 45ˊ-0˝

(13.71m) was fixed. Next these piles were cast at site and cured for twenty eight days.

Mature piles were driven in two locations namely TP-1 (Test pile) and TP-2 (Test pile).

Drop hammer of 3.5 Ton was used and maximum height of fall was 5'-0''. During

driving the driving records were collected for calculating the pile capacity which was

also attached at Appendix B. After 14 days of interval these piles were tested using Pile

Dynamic Analyzer (PDA) Test. At the last two feet (from top) of each pile, transducers

and strain gages were attached with the pile for estimating dynamic capacity by PDA.

Later CAPWAP analysis was carried out using the signal matching techniques for

evaluating refine capacity of piles. Later these piles were tested by static load test

method as well.

3.2 Capacity Estimation

The pile capacity will be calculated by using sub soil investigation report. Methods that

are considered for this study are based on the draft versions of Bangladesh National

Building Code (BNBC-2015), where pile capacity estimation technique is described

both for driven and cast-in-situ piles. It has presented two methods: one is Static

bearing capacity (Alpha-Beta method) and the other is SPT method. Generally,

professional geotechnical expert uses American Association of State Highway and

Transportation Officials guidelines (AASHTO, 2002), which is widely used in

Bangladesh. For this study AASHTO-2002 method is also applied and results are

compared with the BNBC-2015.

During driving the precast piles, there is an option for using the driving equations. This

has also been used for pile capacity estimation. Figure 3.1 summaries the working

process of the study.

33

Figure 3.1: Flow diagram of the working process

From the soil test report it was found that the soil is uniform in horizontal and vertical

direction. Mainly soil type was non-cohesive (Silt followed by Sand) up to the depth of

investigation. Considering the imposed building loading deep foundation was

considered. Figure 3.2 and 3.3 shows the two test borehole logs. The test pile driving

records are attached at Appendix A.

PILE CAPACITY

BASED ON SOIL

TEST REPORT

DRIVING EQUATION

DYNAMIC LOAD TEST (PDA)

STATIC LOAD TEST

1. BNBC-2015

2. AASHTO-2002

1. ENGINEERS NEWS

2. GATES FORMULA

3. JANBU FORMULA

1. DAVISSION METHOD

2. BNBC-93 GUIDELINE

3. BS 8004 (BRITISH STANDARD)

4. IS: 2911 (INDIAN STANDARD)

5. BUTLER & HOY

6. BRINCH HANSEN

CAPWAP ANALYSIS

34

Borehole No-1

Method of boring-Percussion Method Boring dia (mm)-100

Soil Classification- ASTM D-2487 & D-2488

Dep

th b

elow

EG

L(m

)

Thi

ckne

ss (

m)

D

escr

ipti

on o

f

soil

stra

ta

SPT

N-

Val

ue

(Raw

fie

ld d

ata)

Graphical representation of

SPT N-value

1.5

3.0

4.5

6.0

7.5

9.0

10.5

12

13.5

15

16.5

18

19.5

21

22.5

3.75

Brown, non-

plastic, SILT, ML,

trace mica

2

5

9

10

16

20

22

22

24

27

28

35

38

42

42

20.25

Gray, loose to

medium dense,

Silty SAND, SM,

trace mica

Figure 3.2: Borehole log BH-1

35

Borehole No-2

Method of boring-Percussion Method Boring dia (mm)-100

Soil Classification- ASTM D-2487 & D-2488 D

epth

bel

ow

EG

L(m

)

Thi

ckne

ss (

m)

Des

crip

tion

of

soil

stra

ta

SPT

N-

Val

ue

(Raw

fie

ld d

ata)

Graphical representation of

SPT N-value

1.5

3.0

4.5

6.0

7.5

9.0

10.5

12

13.5

15

16.5

18

19.5

21

22.5

2.25

21.7

5

Brown, non-

plastic, SILT, ML,

trace mica

4

7

11

11

12

13

16

10

17

26

26

29

31

35

39

Gray, loose to

medium dense,

Silty SAND, SM,

trace mica

Figure 3.3: Borehole log BH-2

36

3.3 Pile Load Tests

Based on the sub soil investigation, pile length was selected as 45ft with a section of

12''X12'' (300mmX300mm). Initial estimated capacity was 40 Ton following equation

of Schmertmann (1970). Table 3.1 shows the static and dynamic load testing program.

Table 3.1: Load testing program for test piles

Sl. No. Purpose of test Name of the test Number of tests

1. Dynamic Pile Capacity

PDA followed by CAPWAP analysis

2

2. Static Pile Capacity Static Load Test 2

Figure 3.4: Casting of pile at site for construction

3.4 Pile Driving and Keeping Driving Record

Piles are generally marked every one feet of interval and which is visible from the data

observer during record keeping. In a proper formatted data sheet pile penetration and

37

hammer blow need to be recorded for per feet of penetration of pile. Data sheet

provides necessary information like: pile section, length, casting date, pile

identification mark, capacity of pile, hammer weight, drop height of hammer, blows

required for a fixed penetration depth, refusal etc. From the driving of the two piles

initial capacity can be calculated using available driving formulas like Engineering

News, Gate etc. Figure 3.5 shows the driving of pile using a drop hammer.

Figure 3.5: Pile driving using drop hammer

3.5 Dynamic Load Test Arrangement

A typical dynamic testing system consists of a minimum of two strain transducers and

two accelerometers bolted to diametrically two opposite sides of the pile to monitor

strain and acceleration and account for non-uniform impacts and bending. The use of

38

two diametrically opposite mounted strain transducers is essential for a valid test.

Generally, strain transducers and accelerometers are attached two to three diameters

below the pile head.

Figure 3.6 to Figure 3.9 illustrate the typical pile preparation procedures required for

dynamic testing. In Figure 3.6 a concrete pile is being prepared for gage attachment by

drilling. Pile preparation and gage attachment typically requires 10 to 20 minutes per

pile. After the gages are attached, the driving process continues following usual

procedures. The individual cables from each gage are combined into single main cable

which in turn relays the signals from each hammer blow to the data acquisition system

on the ground. The data acquisition system, such as the Pile Driving Analyzer shown in

the Figure 3.7 receives and converts the strain and acceleration signals to force and

velocity records versus time. The force is computed from the measured strain times the

product of the pile elastic modulus, and cross sectional area. The velocity is obtained by

integrating the measured acceleration record. During driving, the Pile Driving Analyzer

performs integrations and all other required computations to analyze the dynamic

records for transferred energy, driving stress, structural integrity, and pile capacity.

Numerical results for dynamic quantities are electronically stored in a file which can be

later used to produce graphical and numeric summary outputs. In this system, force and

velocity records are also viewed on a graphic LCD computer screen during pile driving

to evaluate data quality, soil resistance distribution, and pile integrity. Complete force

and velocity versus time records from each gage are also digitally stored for later

reprocessing and analysis by CAPWAP.

During pile driving in the field, the Pile Driving Analyzer uses the Case Method

capacity equations for estimating the ultimate static pile capacity. Case Method

capacity results are calculated in real time from the measured force and velocity records

obtained for each hammer blow. Correlating Case Method capacity results with pile

penetration resistance information is another means of establishing the driving criteria.

The CAPWAP analysis method is a more rigorous numerical analysis procedure that

uses the measured force and velocity records (PDA data) from one hammer blow. The

CAPWAP program uses the dynamic measurement data along with wave equation and

soil modelling to calculate the ultimate static pile capacity, the relative soil resistance

distribution, the dynamic soil properties of quake and damping, and the driving stresses

39

throughout the pile. CAPWAP capacity results are considered a more accurate

assessment of the ultimate static pile capacity (Likins et al, 1996).

Figure 3.6: Strain transducers and accelerometer bolted on the concrete piles

Figure 3.7: Pile driving analyser

40

Figure 3.8: Dynamic test arrangement for TP-1

Figure 3.9: Dynamic test arrangement for TP-2

3.6 Static Load Test Arrangement

Maintain load (ML) method with standard loading procedure has been followed under

complying ASTM D1143 and load applied by hydraulic ram against Kent ledge. ASTM

D1143 recommends several alternative systems for applying compressive load to the

pile, and measuring movements. Table 3.2 presents load testing details.

Table 3.2: Static load test program

Criteria Attributes

Design Load 40 Ton

Target test load 2.5 X Design load=100 Ton

Type of pile Reinforced concrete pre-cast pile

Dimension 300mmX300mm (12”X12”)

Method of installation Impact hammering

41

Criteria Attributes

Driving equipment Skid mounted pile driver

Hammer detail Drop hammer

Hammer weight=3.5 Ton

Drop height=5 Ft (max)

Compressive loads are applied by hydraulic jacking against a weighted platform. The

primary means of measuring the load applied to the pile should be with a calibrated

load cell. The jack load should also be recorded from a calibrated pressure gauge. Axial

pile movements are usually measured by dial gages that measure the movement

between the pile head and an independently supported reference beam.

Figure 3.10: Schematic diagram of typical arrangement of applying load in an axial compressive test

42

The steps are to be followed is given below:

Arrangement of instrument and calibration.

Preparation of mass of heavy material, termed “Kentledge” is placed on

platform.

Installation of reference beam

Finish pile top for seating hydraulic jack, installation of pile collar, placement

of jack, dial gauges and strain gauges and reading.

Taking safety measures.

3.6.1 Loading sequence

Detailed loading procedure is presented in ASTM D1143 for Maintained load (ML)

test. The general procedure is to apply static loads in increments of 25% of the

anticipated design load (BNBC-2015). According to ASTM D1143 each load

increment is maintained until the rate of settlement is not greater than 0.25mm/hr or 2hr

is elapsed, whichever occurs first. This procedure is applied for all increment of load.

After completion of loading if the test pile has not failed the total test load is removed

any time after twelve hours if the butt settlement over one hour period is not greater

than 0.25mm otherwise the total test load is kept on the pile for 24 hours. After the

required holding time, the test load is removed in decrement of 25% of the total test

load with 1 hour between decrement. If failure occurs, jacking the pile is continued

until the settlement equals 15% of the pile diameter or diagonal dimension.

43

Table 3.3: Typical loading sequence arrangement for pile load test.

Design Load (kip)=80 Design Load (kg)=40,000 Test Load(kg)=100,000 Diameter of ram (cm)=24.13 Area of ram (cm2)=457.30 Regression equation: Y actual(kg/ cm2)=1.019X(kg/ cm2)-5.561

Loading steps

Theoretical As planned

% of Design Load

Load (kg)

Required Pressure (kg/ cm2)

Required Corrected Pressure (kg/ cm2)

Observed

Pressure (kg/ cm2)

Load (kg)

% of Design Load

Holding Time

Reading Intervals

1st increment 25 10,000 21.87 26.92 25 9,107 22.77 A/B 10 min

2nd increment 50 20,000 43.73 48.38 50 20,757 51.89 A/B 10 min

3rd increment 75 30,000 65.60 69.84 70 30,076 75.19 A/B 10 min

4th increment 100 40,000 87.47 91.30 90 39,396 98.49 A/B 10 min






10th increment 250 100,000 218.67 220.05 220 99,975 249.94 C D

1st decrement 187.5 75,000 164.00 166.40 165 74,346 185.86 20 min 10 min

2nd decrement 125 50,000 109.34 112.76 115 51,046 127.62 20 min 10 min

3rd decrement 62.5 25,000 54.67 59.11 60 25,416 63.54 20 min 10 min

4th decrement 0 0 0.00 0.00 0 0 0.00 1 hr 10 min Notes: Holding time: A= Any time, if the rate of settlement is less than 0.25 mm/hr B= Max 2 hr if the rate of settlement is greater than 0.25 mm/hr C= Any time after 12 hr if the butt settlement is not greater than 0.25mm in 1 hr but otherwise 24 hr Reading time: D= At interval 10 min for 1st 1 hr for next 10 hr, 2hr for next 12 hr When pile fails: If the pile fails at any load the pile will be jacked up to 15% of pile diagonal/diameter of settlement.

44

3.7 Data Collection

Data was collected for both precast and cast-in-situ piles were done following the flow diagram.

Figure 3.11: Schematic diagram of data collection for precast and cast in situ piles.

Precast pile

Two piles were tested for both dynamic and static load test at Tangail site. All the soil

investigation report, static load test, dynamic load test data were collected for these two

piles. Total fifteen precast pile data (pile length and cross section), soil investigation

report, dynamic load test data were collected from Public Works Department (PWD).

The Table 3.4 shows the collected data and predicted pile capacity based on different

method.

DATA COLLECTION

SOIL

TEST REPORT

PILE DETAILS DYNAMIC LOAD TEST (PDA)

1. BNBC-2015 (SPT)

2. BNBC-2015 (STATIC BEARING)

3. AASHTO-2002

CAPWAP ANALYSIS

COMPARE & CORELATE

CAPACITY CALCULATION

45

Table 3.4: Data summary for precast pile

SL No

Project name

Pile data Pile capacity

calculated (kN) Collected

capacity CAPWAP

(kN)

Length

(m)

Section

(m x m)

Pile ID BNBC-2015

Static Beari

ng SPT

1 Nursing College, Pabna

21.34 0.3 X 0.3 P-26

(H-07) 793 857 991

2 Nursing College, Pabna

21.34 0.3 X 0.3 P-04 (G-07) 1770 1386 1756

3 Sadar Hospital, Manikganj

13.72 0.3 X 0.3 PC-4 P-4 645 777 822


13.72 0.3 X 0.3 PC-8B P-134 624 803 788


13.72 0.3 X 0.3 PC-5 P-67 710 840 1158


13.72 0.3 X 0.3 PC-4 P-218 603 812 654

7 Teachers Training College, Shariatpur

16.16 0.35 X 0.35

TP-02 834 937 846

8 Teachers Training College, Shariatpur

16.16 0.35 X 0.35

TP-04 867 907 879

9 Bangabandhu Textile Institute, Tangail

13.72 0.3 X 0.3 P-24 1083 1224 1214

10 Bangabandhu Textile Institute, Tangail

13.72 0.3 X 0.3 P-141 649 774 500

11 Keraniganj Sub Jail 12 0.3 X 0.3 TP-2 659 1034 905

12 Cox’s bazar Medical College

12 0.3 X 0.3 TP-2 1282 1310 1402

13 Cox’s bazar 12 0.3 X 0.3 TP-3 1065 1036 1192

14 Medical College 12 0.3 X 0.3 TP-5 1475 1464 1644

15 Teachers Training College, Barguna

16.7 0.35 X 0.35

P-106 1141 1091 1128

Source: Icon Engineering services

Cast-in situ pile

Recently, Padma multipurpose bridge project service area-2, Mogbazar flyover project

and few other projects used dynamic load test. For cast-in situ piles total ten dynamic

load test, soil investigation report and pile data (pile length and cross section) were

46

collected for capacity calculation. Table 3.5 presents the collected data and capacity

calculation based on different method.

Table 3.5: Data summary for cast-in-situ pile

SL No

Project Name

Pile Data Pile capacity calculated

(kN) Collected Capacity

CAPWAP (kN)

Diameter (m)

Length (m)

BNBC-2015 SPT

BNBC-2015 Static bearin

g AASHTO-2002

1 Walton Office, Basundhara, Dhaka *

0.5 28.5 1503 1435 2130 2118

2 Titas Railway Bridge, Akhaura *

1.2 30.8 5036 6016 4984 5000

3 Padma Bridge, Naodoba, Zazira, Shariatpur *

1.2 29.5 3141 4291 4924 3520

4 Mogbazar Fly over, Dhaka*

1.2 29.5 4911 4204 6328 5043


1.5 44.4 9185 7907 10936 10374


1.2 44 6516 6611 8009 7221

7 Dhaka Road research Lab( P1) #

1 22.5 2280 2753 3406 2196

8 Dhaka Road research Lab(P2) #

1 28 3987 3221 3630 4589

9 Zinzira-Nawabganj Bridge (LRP,P3) #

1 23.7 4005 3339 3784 3635

10 Zinzira-Nawabganj Bridge (LRP,P4) #

1.2 24 5239 2760 3854 3408

Source: * Icon Engineering services, # Prosoil

3.8 Summary

The test program focuses on two test pile which will provide adequate information

regarding pile capacity. After load test confirmation both static and dynamic will allow

the opportunity to compare with the predicted capacity by different methods in detail.

Later data collection of soil test report, pile details and CAPWAP capacity will be done

for both precast and cast in situ piles. Pile capacity prediction by different method will

be done using the collected data which will be compared with CAPWAP capacity.

47

CHAPTER 4

RESULTS AND DISCUSSIONS

4.1 General

In this study, the main focus is to determine compressive load capacity of piles using

different existing methods of pile capacity estimation and compare with dynamic and

static load test. In this chapter pile capacity calculation was done based on BNBC-

2015(Static bearing capacity and SPT methods) and AASHTO-2002. For selected two

precast test pile capacity was predicted and later compared with CAPWAP and static

load test. Later part of the study uses collected data for capacity prediction and

correlate with CAPWAP capacity for precast and cast in situ piles.

4.2 Pile Capacity of Precast Piles Using Driving Equations

Using pile driving record the capacity was calculated for two testing piles. In this test

drop hammer weight was 3.5 ton. Piles were marked per 0.3m (1'-0'') interval and lifted

by one point lifting at 4.5m from the top. After fixing the pile with the tripod stand the

hammer dropped from height varying from 0.6m (2'-0'') to max 1.52m (5'-0''). From the

driving chart it was evident that the pile section penetrated up to 4.57m (15'-0'') by self-

weight. Next each penetration of 0.3m (1'-0'') required 12 to 37 numbers of blows.

Engineers News Formula, Janbu and Gates formula was used for capacity calculation.

In the Engineering News formula efficiency of drop hammer value 0.75 was considered

according to Bowles (1997). Resistance under working load was calculated using

equation 2.36. In this formula only weight of ram, point penetration per blow, height of

ram need to be considered. Engineering News and Janbu equations are based on

impulse momentum principles with various assumptions. The calculations of pile

capacity based on the driving formulas are attached in the Appendix-C.

4.3 Pile Capacity Using PDA Test Results

Dynamic testing on the piles was conducted by striking the piles by several blows.

During testing of pile, complete dynamic measurements were obtained for each

hammer blow delivered to the pile. The input of a weave equation analysis consists of

information about the soil, pile, hammer, cushions, and any other devices which

participates in the transfer of energy from hammer to soil.

48

In this test re-strike method was applied on driven pile. Before testing the upper portion

of pile 150mm to 225mm (6'' to 9'') was recast and a smooth top was prepared for

maintain level for hammer impact over pile top properly. Weight of the hammer was

1600kg. The sensor both strains gages and accelerometers were placed 0.6m (2'-0'')

below the pile top. Height of fall was 1m. For analysis pile segment was divided into

six segments. Ply wood was used as cushion material in two layers each was 16mm

thick. Elastic modulus of pile material was considered 23500 MPa. Wave speed and

specific weight of concrete was 3500 m/s and 24.5 kN/m3 consecutively. Soil

parameters like quake skin, quake toe, damping skin, damping toe was used as the

default values provided by PDA.

In Figure 4.1 hammer blows were given to TP-1 and all the records were measured.

Capacity found at the field PDA is represented by Rsu=1346 kN and Rmx=1408kN.

The degree of convergence between the force and velocity records is expressed by the

BTA (Beta value) integrity value as a percentage of the approximate reduce cross

sectional area. Pile integrity, BTA, value reading 100% indicate no damage was

present.

Table 4.1: Beta value for pile integrity (Rausche and Goble, 1979).

Beta value Pile condition

100% OK

60% -80% Slightly damage

≤60% Damage

49

Figure: 4.1: Force and velocity record for TP-1.

For TP-2 hammer blows were given and data was collected. Pile integrity BTA is 73%

which indicate pile defect i.e. reduction of cross section area. Capacity found at the

field PDA is represented by Rsu=1317 kN and Rmx=569kN. The data record of force

and velocity presented in the Figure 4.2. The PDA measures the total (static and

dynamic) resistance acting on the pile. Table 4.2 shows the pile capacity using PDA.

Table 4.2: Capacity of piles using PDA.

Capacity (kN) TP-1(P-24) TP-2(P-141)

Rsu 1396 1317

Rmx 1408 569

50

Figure 4.2: Force and velocity record for TP-2

4.4 CAPWAP Analysis

CAPWAP (CAse Pile Wave Analysis Program) is a signal matching procedure based

on pile top force and velocity measurements during hammer impact, extracts static and

dynamic soil resistance parameters for pile shaft and toe. It refines the raw data of PDA

by signal matching procedure through iteration. In Figure 4.3 and 4.4 shows CAPWAP

force wave matching was done for TP-1 and TP-2. A reasonable matching was done in

shaft, toe resistance, total resistance and soil unloading behaviour starting from zone 1

to 4. A large separation between force and velocity record in Figure 4.5 suggests a large

shaft resistance on the pile. From the analysis the shaft resistance was found 1213.6 kN

and toe resistance 297.9 kN which support the point.

51

Figure 4.3: CAPWAP Iteration force matched graph for TP-1

A rigorous CAPWAP analysis of the data acquired from the PDA, confirmed that the

pile had achieved an activated CAPWAP capacity of 1213.6 KN.

In Figure 4.5 showed a reasonable match of force wave. Though both zone 2 and zone

3 disagrees slightly regarding matching. The resulting model will fairly estimate static

pile capacity, soil resistance distribution, soil quake and damping characteristics.

Figure 4.4: CAPWAP Iteration force matched graph for TP-2

From the Figure 4.5 it was found that a minimum separation occurred between the

force and velocity records between time O, or the time of impact and time 2L/c. Hence

this record indicated a minimum shaft and tow resistance on the pile. A rigorous

52

CAPWAP analysis of the data acquired from the PDA, confirmed that the pile had

achieved an activated CAPWAP capacity of 499.9 kN. There is a 45.11% reduction of

pile impedance at around 4.0m below the sensors which indicates a major defect.

Figure 4.5: Investigation of pile damage and beta factor

Table 4.3: Summary of dynamic test

Test pile ID TP-1 TP-2

Type of Testing Restrike

Blow Number 5 4

Pile Length (m) 13.719 13.719

Le (m) 13.10 13.10

Lp (m) 13.70 13.70

Max Comp. stress (MPa) 20.40 12.20

Set (DFN) (mm) 3.00 3.00

CAPWAP Capacity

Shaft (kN) 915.7 369.4

Toe (kN) 297.9 130.5

Total (kN) 1213.6 499.9

53

4.5 Pile Capacity from Pile Load Test

Static pile capacity was determined in the TP-1 and TP-2 piles. Design load was 40 ton

and the target load was 2.5 times the design load i.e. 100 ton. Using the test settlement

under working load, adequacy of bearing capacity will be ensured. Maintained load test

were performed to accomplish the above objectives.

In case of TP-1 loading was done in ten consecutive steps which produce settlement 8.9

mm at a final loading of 99,975 kg for 12 hour. The unloading causes a 3.57 mm

permanent settlement. One cycle of loading and unloading was done for the load test.

During the test the settlement was within the capacity of the pile which suggests the

pile capacity is more than the design load arrangement. After the test the Davission

offset method applied which shows no point of failure. Other methods were applied for

calculating the pile capacity.

Figure 4.6: Load settlement graph for pile load test TP-1

In case of TP-2 one cycle of loading was done up to design load and unload was done.

Later pile load was increased up to the test load previously set. At load 90,318 kg load

settlement was 37.96mm. After the unloading it experience 30.03 mm permanent set.

0

2

4

6

8

10

12

14

16

18

200 15 30 45 60 75 90 105 120

Pile

set

tlem

ent (

mm

)

Load (MT)

Davission offset line, out of range

54

Figure 4.7: Load settlement graph for pile load test TP-2

For TP-1 ultimate capacity pile is more than 1000 kN and for TP-2 capacity was

derived using different methods. The capacity trend of static load test is similar to the

CAPWAP analysis. The pile load test summary is given below for the two piles in

Table 4.4.

Table 4.4: Test result summary

Pile ID

Capacity Ton (kN)

Davission Offset

BS 8004 IS: 2911 Butler and Hoy

Brinch Hansen

TP-1 Out of range Out of range

Out of range Out of range Out of range

TP-2 81 Ton

(807 kN)

88.5 Ton

(881 kN)

78 Ton

(777 kN)

79 Ton

(787 kN)

+90 Ton

(896 kN)

Table 4.5 presents the pile capacity for two piles in different methods. From the Table

4.4 shows that pile capacity using Janbu formula provides higher capacity for both

piles.

0

5

10

15

20

25

30

35

400 15 30 45 60 75 90 105 120

Pile

set

tlem

ent (

mm

)

Load (MT)

Davission offset line

55

Table 4.5: Pile capacities from driving formulas

Formulas used Total resistance

TP-1(kN)

Total resistance

TP-2(kN)

Engineering News 804 792

Janbu 1790 1733 Gates 1049 1026 CAPWAP(Dynamic) 1213 500 Static (Average) 1000 830

However, Engineers News formula provides the least capacity value. Gates formula

provides closer values comparing with the CAPWAP dynamic analysis. However,

driving formulas fail to provide information of pile condition during driving. Static pile

load test resembles with the CAPWAP capacity for the two piles though the capacity

differs maximum 40%.

4.6 Pile Capacity Summary

Fifteen dynamic test data of precast pile were collected. In the data predicted pile

capacity, CAPWAP analysis was available. By observing the collected data the

following comments were made.

1. There is good co-relation exist with the BNBC-15 methods with the CAPWAP

capacity, which is shown in Figure 4.8 and 4.9. For BNBC-15 Static method an

equation was developed as CAPWAP capacity =1.10X BNBC 2015 Static capacity and

r2=0.81.

For the case of BNBC SPT the equation was developed as CAPWAP capacity=1.06X

BNBC 2015 SPT capacity and r2=0.77.

2. Generally, BNBC-2015 Static capacity method under predict precast pile capacities

most of the times (87%) comparing with the CAPWAP capacity.

3. CAPWAP analysis suggests that due to layer change in same vicinity pile capacity

can be different. That is also reflected in the calculation of BNBC-2015 static bearing

method.

56

4. CAPWAP analysis shows exact precast piles capacity considering the integrity of

pile, as well as soil damping, driving and other relevant issues. If during driving the

pile is injured it shows the integrity by beta value. Predicted pile capacity can very

considering these variable which is beyond the scope of traditional equations based on

soil parameter.

Figure 4.8: Correlation between CAPWAP and BNBC 2015 (static bearing) pile

capacity for precast pile

CAPWAP capacity= 1.10xBNBC2015 Static Capacityr² = 0.81

0

250

500

750

1000

1250

1500

0 250 500 750 1000 1250 1500

CA

PW

AP

cap

acit

y (k

N)

BNBC-2015 Static bearing capacity(kN)

57

Figure 4.9: Correlation between CAPWAP and BNBC 2015 (SPT) and pile capacity for precast pile

4.7 Comparison with Collected Data for Cast-In-Situ Piles

Data of ten cast-in-situ piles were collected. In the data predicted pile capacity,

CAPWAP analysis was also available. Following observations were found

1. In case of cast-in-situ piles the predicted capacity generally agrees with the

CAPWAP capacity.

2. There is very good co-relation exist between BNBC-2015 static bearing capacity of

pile with the CAPWAP capacity for these cast-in-situ piles. The equation was

developed as CAPWAP capacity=1.15X BNBC 20215 static capacity and r2=0.81

which is shown in Figure 4.10.

CAPWAP capacity = 1.06x BNBC 2015 SPT capacityr² = 0.77

0

250

500

750

1000

1250

1500

1750

2000

0 250 500 750 1000 1250 1500 1750 2000

CA

PW

AP

cap

acit

y (k

N)

BNBC-2015 SPT capacity(kN)

58

Figure 4.10: Correlation between CAPWAP and BNBC-2015 (static bearing) capacity.

3. The co-relation between BNBC-2015 SPT cast-in-situ pile and CAPWAP is

developed as CAPWAP capacity=1.04X BNBC SPT capacity and r2=0.89 which is

shown by Figure 4.11.

4. The co-relation between AASHTO-2002 cast-in-situ pile and CAPWAP is developed

as CAPWAP capacity=0.91X AASHTO 2002 capacity and r2=0.92 which is presented

by Figure 4.12.

CAPWAP capacity = 1.15x BNBC 2015 Static bearing capacity r² = 0.81

0

2000

4000

6000

8000

10000

0 2000 4000 6000 8000 10000

CA

PW

AP

cap

acit

y (k

N)

BNBC-2015 Static bearing capacity(kN)

59

Figure 4.11: Correlation between CAPWAP capacity and BNBC-2015 SPT capacity for cast-in-situ pile

Figure 4.12: Correlation between CAPWAP and AASHTO-2002 pile capacity for cast-in-situ piles.

4.8 Summary

There is a very good co-relationship exist with static pile load test and dynamic load

test which is evident in this case. In a mega project where pile number is huge it is very

CAPWAP capacity = 1.04x BNBC 2015 SPTcapacityr² = 0.89

0

2000

4000

6000

8000

10000

0 2000 4000 6000 8000 10000

CA

PW

AP

cap

acit

y (k

N)

BNBC-2015 SPT capacity(kN)

CAPWAP capacity = 0.91x AASHTO 2002 capacity r² = 0.92

0

2000

4000

6000

8000

10000

0 2000 4000 6000 8000 10000

CA

PW

AP

cap

acit

y (k

N)

AASHTO capacity(kN)

60

difficult to carry out the static load test frequently due to shortage of money or time.

Application of dynamic test may be appropriate in those conditions.

In the upcoming BNBC-2015 the static bearing capacity method and SPT methods are

presented as a guideline for calculating both precast and cast-in-situ piles. Geotechnical

experts over the years are familiar with the AASHTO-2002 method for practicing real

life work. Considering both soil test report and CAPWAP analysis co-relationships

were established for precast and cast-in-situ piles. Further study is necessary in this

regard to validate proposed equations of BNBC-2015.

During the study it was found that beta value is a very good indicator for pile integrity.

In case of cast-in-situ piles it shows the casting quality and in case of precast pile it

suggests the pile condition after driving. This is an excellent tool need to be utilized

properly by our professionals.

61

CHAPTER 5

CONCLUSIONS

5.1 General

The aim of the study was to determine the ultimate pile load capacity using Pile

Dynamic Analyzer (PDA) along with static load test which is very common in our

country. For the two test pile (precast) this was done together with the driving

equations, BNBC-2015 guideline and AASHTO-2002. Later for fifteen precast pile and

ten cast-in-situ pile CAPWAP analysis, BNBC-2015 capacity, AASHTO-2002 capacity

was also used to summarized and establish co-relations.

5.2 Concluding Remarks

Pile capacity was calculated for two test piles (TP-1 and TP-2) of this study using

driving record. In each method the capacity of two piles are close. It suggests that soil

variation in those two piles were not considered in driving equations. Each driving

equation shows same pair of pile capacity values derived from Engineer’s News, Janbu

and Gates formula. However, inconsistency of capacity was observed. Results suggest

that these methods should not be applied due to large inconsistency in capacity

prediction.

Capacity from static pile load test and dynamic load test for the two piles are close. In

case of capacity obtained from BNBC-2015 guidelines and AASHTO-2002 fails to

match with TP-2 but aggress well with TP-1. From dynamic load test it was found that

beta factor for TP-1 was 100% and beta factor for TP-2 was 73%. This suggests TP-2

has major defects. It can be concluded that predicted pile capacity can vary widely if

piles were not properly casted (in case of cast-in-situ pile) or driven (in case of precast

pile) maintaining quality.

In case of collected sample data analysis of soil test report, Dynamic Load Test,

BNBC-2015 and AASHTO-2002 very useful co-relationships has been established. It

can be improved by further study.

62

5.3 Recommendations

From the lessons of the present study, the recommendations for future study may be

summarized as follows:

In this study, only the capacity of piles was estimated and compared but the

effect of soil ‘set-up’ (change of soil strength and adhesion) was not considered. Thus

considering the effect of soil set-up modified pile capacity can be studied. This can be

done by assessing a pile capacity after a time interval using dynamic load test.

In our country selection of pile hammer depends on the availability of hammer.

Proper selection of hammer or study is necessary for driving a pile without damaging it.

This can be ensured by using PDA data of energy transfer ratio, pile stress and other

indicator for optimize the appropriate diesel hammer. Application of drop hammer

should be restricted for important projects.

Attention should be given to beta values from the PDA during driving and take

note any possible damage on the driving record. That will reduce the chance of

overdriving of piles.

There is no study for selection of damping factor and quake value for

Bangladesh for CAPWAP analysis. Only prescribed guideline is used for signal

matching. There is a scope to develop site specific factors for Bangladesh.

Though dynamic analysis is already use in our country there is no guideline in

BNBC-2015. There should be a guideline along with standard to use it efficiently.

63

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ASTM D 1143-81(Reapproved 1994). “Standard Test Method for Piles under Static

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ASTM D 1586-08a, “Standard Test Method for Penetration Test (SPT) and Split-Barrel

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ASTM D4945-00, “Standard Test Method for High Strain Testing of Piles”.

Bowles, E.J. (1997). “Foundation analysis and design”, 5th Edition, The Mcgraw Hill

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Brinch Hansen, J. (1963). “Discussion, Hyperbolic stress-strain response. Cohesive

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BSI, (1986). “British Standard Code of Practice for Foundations (BS 8004: 1986)”.

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Burland, J.B. (1973). “Shaft Friction of Piles in Clay- A Simple Fundamental

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Butler, H.D. and Hoy, H.E. (1977). “The Texas Quick Load Method for Foundation

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Chellis R.D. (1961). “Pile Foundations”. Second Edition, McGraw-Hill Book

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Davisson, M.T. (1972). “High Capacity Piles, Proceedings, Soil Mechanics Lecture

Series on Innovations in Foundation Construction”. American Society of Civil

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Engeling, D. and Reese, L.C. (1974). “Behaviour of Three Instrumented Drilled Shafts

Under Short Term Axial Loading,” Research Report No 176-3, Project 3-5-72-

176, conducted for the Texas Highway Department, in cooperation with the

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Forehand, P. W. & Reese, J.L. (1964). “Prediction of Pile Capacity by the Wave

Equation.” J.S.M.F.D., ASCE, vol. 90, SM2:1-25.

Fuller, F.M. (1983). “Engineering of Pile Installations”, McGraw-Hill, New York, 286.

Gates, M. (1957). “Empirical Formula for Predicting Pile Bearing Capacity,” Civil

Engineering, ASCE, vol. 27, no. 3, March, pp.65-66.

Glanville, W. H., Grime, G., Fox, E.N, & Davies, W.W. (1938). “An Investigation of

the Stresses in Reinforced Concrete Piles during Driving.” Br. Bldg. Res. Bd.,

tech. paper no. 20, D.S.I.R.

Hoque, Siddiquee, M.S.A., and Ameen, S.F. (1999). “Improvements in Instrumentation

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Housing and Building Research Institute (HBRI) & Bangladesh Standards and Testing

Institution (BSTl), (2015). “Draft final of Bangladesh National Building Code

(BNBC)”, Dhaka, Bangladesh

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Load Test on Piles”, Bureau of Indian Standards, New Delhi.

Isaacs, D.V. (1931). “Reinforced Concrete Pile Formulae”. Trans. Instn. Engrs. Aust.,

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65

Kaniraj, S.R (1988). “Design Aids in soil Mechanics and foundation Engineering”,

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Engg. Project, BUET.

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Resistance of CIDH piles.” Proceedings, Foundation Engineering: Current

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Lowery, L.L., Hirsch, T.J., Edwards, T.C., Coyle, H.M., & Samson, C.H., (1969). “Use

of the Wave Equations to Predict Soil Resistance on a Pile during Driving.”

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Morshed, J. (1991). “Prediction of Load Deformation Behaviour of Axially Loaded

Piles in Sand”, M.Sc. Engg. Thesis, BUET.

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PDI (1996). “Pile Driving Analyzer”, Model PAK. Pile Dynamic Inc., Cleveland, Ohio,

22p.

Poulos, H.G. and Davis, E.H. (1980). “Pile Foundation Analysis and Design”.

Newyork, Wiley.

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based on CPT”, M. Engg. Project, BUET.

Rausche, F., and Goble, G.G. (1979). “Determination of Pile Damages by top

measurements”. Behavior of Deep Foundations, ASTM, STP 670, Raymond

Lundgren, Editor. American Society of Testing and Materials: 500-506.

66

Rausche, F., Goble, G.G. &Likins, G.E. (1985). “Dynamic determination of pile

capacity”. Journal of Geotechnical Engineering, American Society of Civil

Engineers, vol. 111, pp 367-383.

Rausche, F., Robinson, B. & L. Liang (2000). Automatic Signal Matching with

CAPWAP, Application of Stress-Wave Theory to piles, Niyama & Belm (eds),

Balkema, Rotterdam.

Reese, L. C., O’Neill, M. W. (1988). “Field Load Test of Drilled Shaft,” Proceedings,

International Seminar on Deep Foundations on Bored and Auger Piles, Van

Impe (ed.), Balkema, Rotterdam, 145-192

Seed, H. B. & Reese, L.C. (1957). “The Action of Soft Clay along Friction Piles.”

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Research Congress, London, pp. 180 -189.

Smith, E.A.L. (1960). “Pile Driving Analysis by the Wave Equation”. American

Society of Civil Engineers, Journal of the Soil Mechanics and Foundations

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Soderberg, L.O. (1962). “Discussion to Paper by E.A.L. Smith. Trans. ASCE: 1171-

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Terzaghi, K. (1942). “Discussion of the Progress Report of the Committee on the

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Tomlinson, M. J. (1970)."Adhesion of Piles in Stiff Clay," Report 26, Construction

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Tomlinson, M.J., (1986). “Foundation Design and Construction”, 5th Ed., Longman

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Whitaker, T. (1963).“The Constant Rate of Penetration Test for the Determination of

Ultimate Bearing Capacity of Pile,” Proceedings, Institution of Civil Engineers,

Vol.26, London, England, pp 119-123.

67

APPENDIX A

PILE DRIVING RECORDS OF TP-1 AND TP-2

68

PILE DRIVING RECORD OF TP-1

Name of the project: Bangabondhu Textile Engineering College Tangail, (Boys hostel) Location of the project: Kalihati Tangail Pile length: 45ft (13.71m) Pile section: 12”X12”(300 mm X300mm) Weight of hammer: 3.5 Ton Hammer Type: Drop hammer

Table B1: Pile driving data of TP-1

Pile id no Depth driven (ft) Height of fall (ft) Number of blows Remarks

TP-1 1 - -

Pile

penetrated

due to self-

weight only.

2 - - 3 - - 4 - - 5 - - 6 - - 7 - - 8 - -

9 - - 10 - - 11 2 1 12 2 1 13 2 1 14 4 2 15 4 2 16 4 2 17 4 2 18 4 3 19 4 3 20 4 3 21 4 3 22 4 4 23 4 4 24 4 4 25 4 5 26 4 5 27 4 6 28 4 7 29 4 8 30 4 9 31 4 10 32 4 14 33 4 15 34 4 17

69


35 4 24 36 4 26 37 4 24 38 4 22 39 4 24 40 5 26 41 5 32 42 5 33 43 5 35 44 5 36 45 5 40

70

PILE DRIVING RECORD OF TP-2

Name of the project: Bangabondhu Textile Engineering College Tangail , (Boys hostel) Location of the project: Kalihati Tangail Pile length: 45ft (13.71m) Pile section: 12”X12” (300 mm X300mm) Weight of hammer: 3.5 Ton Hammer Type: Drop hammer

Table B2: Pile driving data of TP-2


TP-2 1 - -

Pile

penetrated

due to self-

weight only.

2 - - 3 - - 4 - - 5 - - 6 - - 7 - - 8 - - 9 - - 10 - - 11 2 1 12 2 1 13 2 1 14 4 2 15 4 2 16 4 2 17 4 2 18 4 3 19 4 3 20 4 3 21 4 3 22 4 4 23 4 4 24 4 4 25 4 5 26 4 5 27 4 6

28 4 8 29 4 9 30 4 9 31 4 11 32 4 13 33 4 15 34 4 19

35 4 21

71


36 4 22 37 4 24 38 4 26

TP-2 39 4 27 40 5 25 41 5 30 42 5 32 43 5 35 44 5 35 45 5 37

72

APPENDIX B

CAPACITY CALCULATION OF TWO TEST PILES USING DRIVING EQUATIONS

73

1.A) ENGINEERING NEWS FORMULA (TP-1)

Weight of ram, Wh = 3.5 Ton

Number of blows for last one feet of penetration = 40 Nos

Penetration of pile under last blow of hammer, s = 0.30 in

Height of fall of ram, H = 5 ft

Resistance under working load, R = Wh.H/(s+1)

= 13.46 Ton

= 134 kN FS=6

Ultimate capacity = 804 kN

1.B) ENGINEERING NEWS FORMULA (TP-2)

Weight of ram, Wh = 3.5 Ton

Number of blows for last one feet of penetration = 37 Nos

Penetration of pile under last blow of hammer, s = 0.32 in

Height of fall of ram, H = 5 ft

Resistance under working load, R = Wh.H/(s+1)

= 13.21 Ton

= 132 kN FS=6

Ultimate capacity = 792 kN

2.A) JANBU FORMULA (TP-1)

Pile area, A = 144 sqin

Length of pile, L = 45 ft

Weight of pile, Wp = 6.75 kip

Compressive strength of concrete, f'c = 3500 psi

Modulus of elasticity of concrete, Ec = 57500√3500

= 3401746 psi

= 3402 Ksi

AE = 489851 Kip

cd = 0.75+0.15(Wp/Wr)

= 0.75

74

For drop hammer, eh = 0.75

Weight of hammer = 7.00 kip

Height of fall = 5.00 ft

Eh = 35.00 ft-lb

s = 0.30

λ = ehEhL/AEs2

= 3.86

ku = Cd(1+√(1+(λ/Cd))

= 2.61

Pu = ehEh/kus

= 402.44 Kip

= 1790.12 kN

Fs = 4.5

2.B) JANBU FORMULA (TP-2)

Pile area, A = 144 sqin

Length of pile, L = 45 ft

Weight of pile, Wp = 6.75 kip

Compressive strength of concrete, f'c = 3500 psi

Modulus of elasticity of concrete,Ec = 57500√3500

= 3401746 psi

= 3402 Ksi

AE = 489851 Kip

cd = 0.75+0.15(Wp/Wr)

= 0.75

For drop hammer, eh = 0.75

Weight of hammer = 7.00 kip

Height of fall = 5.00 ft

Eh = 35.00 ft-lb

s = 0.32

λ = ehEhL/AEs2

= 3.30

ku = Cd(1+√(1+(λ/Cd))

75

= 2.49

Pu = ehEh/kus

= 389.57 Kip

= 1732.89 kN

Fs = 4.5

3.A) GATES FORMULA (TP-1)

Pu = a√(ehEh(b-logs)

s a b

FPS in 27 1

Hammer wt = 7 kip

Drop of hammer = 5 ft

Eh = 35 kip-ft

eh = 0.75

s = 0.30 in/blow

SF = 3

Pu = 210.67 Kip

= 1049.55 kN

3.B) GATES FORMULA (TP-2)

Pu = a√(ehEh(b-logs)

s a b

FPS in 27 1

Hammer wt = 7 kip

Drop of hammer = 5 ft

Eh = 35 kip-ft

eh = 0.75

s = 0.32 in/blow

SF = 3

Pu = 205.98 Kip

= 1026.21 kN

76

APPENDIX C

CAPACITY CALCULATION OF PRECAST PILES

(BNBC 2015 STATIC FORMULA AND SPT METHOD)

77

SL No : 1 (Precast pile) Method

: BNBC-2015 Static formula (α and β method)

Site

: Pabna Pile ID : P-26(H -07) Pile sec : 0.3mX0.3m Length : 21.34m

Soil Profile and properties Bore Hole Data of BH-5

Soil Depth

(m) SPT ϕ °

sil 1.5 4 24

3 3 23

Clay 4.5 2

silt 6 2 21

7.5 4 24

Clay 9 5

10.5 11 30

12 17 33

13.5 21 35

silt 15 18 34

16.5 16 33

18 11 30

Clay 19.5 13

silt 21 13 31

Avg Angle of internal friction ϕ = 29

Friction factor β= 0.10 Confirm from chart

Unit wt of soil γ= 17.29 kN/m3

Unit skin friction f = 17.45 kPa (Equation 2.8)

Skin friction Q = 400 kN (Equation 2.2)

Bearing capacity factor N = 28 (L/d=71)

Effective vertical stress σ = 174.49≤240 kPa=174.49 kPa

Unit end bearing f = 4886 kN/m2 (Equation 2.11)

End bearing Q = 468 kN (Equation 2.3)

Weight of pile W= 46 kN

Total ultimate capacity 𝐐𝐮𝐥𝐭= 857 kN (Equation 2.1)

78



Site

: Pabna Pile ID : P-04(G -07) Pile sec : 0.3mX0.3m Length : 22.5m


Soil Depth

(m) SPT φ°

Cu (kPa)

α

1.5 3 23

ML 3 4 24

4.5 2 21

6 4 24

7.5 5 25

CL 9 3 23 72.78 0.50

10.5 12 30

12 14 32

ML 13.5 18 34

15 19 34

16.5 12 30

CL 18 14 32 134.06 0.5

19.5 16 33

SM 21 19 34

22.5 25 37

Angle of friction ϕ = 29 (Avg)



Unit skin friction f = 17.45kPa(1-4.5m), 36.39kPa(6-

2m),3.71kPa(12-5m),67.03kPa(16.5-19.5m)

(Equation 2.8)

and fs=α cu


Bearing capacity N = 65 (L/d=75)

Effective stress σ = 168≤240 kPa=168 kPa





79



Site

: Manikgonj Pile ID : PC-4 P-4 Pile sec : 0.3mX0.3m Length : 13.72m


Soil Depth

(m) SPT ϕ°

1.5 2 21

Silt 3 1 19

4.5 1 19

6 2 21

7.5 4 24

9 12 30

10.5 14 32

SM 12 16 33

13.5 18 34







Effective vertical stress σ = 117≤240 kPa=117 kPa





80



Site

: Manikgonj Pile ID : PC-8B P-134 Pile sec : 0.3mX0.3m Length : 13.72m


Soil Depth

(m) SPT ϕ°

1.5 1 19

Silt 3 1 19

4.5 2 21

6 2 21

7.5 6 26

9 8 28

10.5 11 30

Sand 12 15 32

13.5 17 33












81



Site



Soil Depth

(m) SPT 𝛟 °

1.5 1 19

ML 3 2 21

4.5 2 21

6 2 21

7.5 4 24

9 7 27

10.5 8 28

SM 12 17 33

13.5 18 34




Unit skin friction f = 11.74 kPa (1-6m),11.74 Kpa (Equation 2.8)








82



Site



Soil Depth

(m) SPT

𝛟 °

1.5 4 24

Silt 3 4 24 (MH)

4.5 1 19

6 2 21

7.5 4 24

9 8 28

10.5 12 30

Sand 12 14 32 (SM)

13.5 17 33




Unit skin friction f = 12.92 Kpa (Equation 2.8)








83



Site

: Shariat Pile ID : TP -02 Pile sec : 0.35mX0.35m Length : 16.16m


Soil Depth

(m) SPT 𝛟 °

1.5 3 23

ML 3 3 23

4.5 10 29

6 7 27

7.5 8 28

9 20 35

10.5 8 28

SM 12 14 32

13.5 15 32

15 18 34

16.5 14 32












84



Site



Soil Depth

(m) SPT 𝛟 °

1.5 4 24

ML 3 2 21

4.5 8 28

6 4 24

7.5 8 28

9 17 33

10.5 14 32

SM 12 18 34

13.5 16 33

15 20 35

16.5 15 32












85



Site

: Tangail Pile ID : P -24 Pile sec : 0.35mX0.35m Length : 16.16m


Soil Depth

(m) SPT

𝛟 °

1.5 2 21

Silt 3 5 25 (ML)

4.5 9 28

6 10 29

7.5 16 33

9 18 34

10.5 19 34

Sand 12 18 34 (SM)

13.5 19 34






Bearing capacity factor N = 90





Total ultimate capacity Q = 1083 kN (Equation 2.1)

86



Site



Soil Depth

(m) SPT 𝛟 °

Silt 1.5 5 25 (MH)

3 7 27

4.5 9 28

6 10 29

7.5 11 30

9 16 33

10.5 14 32

Sand 12 10 29 (SM)

13.5 13 31






Bearing capacity factor N = 49 L/d=46






87



Site

: Keranigonj Pile ID : TP -2 Pile sec : 0.3mX0.3m Length : 12m


Soil Depth

(m) SPT 𝛟 °

1.5 6 26

3 6 26

Silt 4.5 5 25

6 7 27

7.5 8 28

9 16 33

10.5 17 33

Sand 12 17 33

13.5 19 34

15 20 35












88



Site

: Coxs Bazar Pile ID : TP -02 Pile sec : 0.3mX0.3m Length : 12m


Soil Depth

(m) SPT 𝛟 °

1.5 4 24

3 2 21

4.5 5 25

Sand 6 10 29

7.5 25 37

9 19 34

10.5 20 35

12 26 38












89



Site



Soil Depth

(m) SPT 𝛟 °

1.5 1 19

3 3 23

silt 4.5 3 23

6 5 25

7.5 5 25

9 6 26

10.5 16 33

Sand 12 5 25

13.5 24 37











Total ultimate capacity Q = 1065 kN (Equation 2.1)

90



Site



Soil Depth

(m) SPT

φ°

silt 1.5 4 24

3 2 21

4.5 5 25

6 10 29

7.5 25 37

9 19 34

10.5 20 35

Sand 12 26 38

13.5 32 40












91



Site

: Borguna Pile ID : P-106 Pile sec : 0.35mX0.35m Length : 16.7 : 16.7m


Soil Depth

(m) SPT 𝛟 °

1.5 1 19

3 1 19

4.5 2 21

6 2 21

7.5 4 24

9 8 28

10.5 11 30

Sand 12 11 30

13.5 14 32

15 14 32

16.5 17 33












92


: BNBC-2015 SPT Based

Site

: Pabna Pile ID : P-26(H -07) Pile sec : 0.3mX0.3m Length : 21.34m


Soil Depth

(m) SPT

silt 1.5 4

3 3

Clay 4.5 2

silt 6 2

7.5 4

Clay 9 5

10.5 11

12 17

13.5 21

silt 15 18

16.5 16

18 11

Clay 19.5 13

silt 21 13

Average N-value N = 10

N-value at pile tip N = 13

Unit skin friction f = 17 kPa≤60 kPa (Equation 2.15)

Unit end bearing f =

=

27742 kPa ≤5200 kPa ≤11000 kPa

5200 kPa

(Equation 2.17)





93



Site

: Pabna Pile ID : P-04(G -07) Pile sec : 0.3mX0.3m Length : 22.5m


Soil Depth

(m) SPT

𝐍𝟔𝟎

1.5 3 3 silt 3 4

4.5 2

6 4

8 7.5 5

Clay 9 3

10.5 12

12 14

silt 13.5 18 19

15 19

16.5 12 14 Clay 18 14

19.5 16

21 19

Sand 22.5 25 22

Average N-value N = As per table


Unit skin friction f = 5. kPa (0-4.5m);13.68 kPa (4.5m-12m),31.45

kPa (13.5-15m),25.2 kPa (16.5-19.5m),37.40

kPa (21m-End)

(Equation

2.15&2.12)


=

75000 kPa ≤10000 kPa ≤11000 kPa

10000 kPa

(Equation

2.17)

Skin friction Q = 535kN (Equation 2.2)



Total capacity 𝐐𝐮𝐥𝐭= 1386 kN (Equation 2.1)

94



Site



Soil Depth

(m) SPT 𝐍𝟔𝟎

1.5 2

Silt 3 1

4.5 1

6 2

2

7.5 4

9 12

10.5 14

Sand 12 16 15

13.5 18



Unit skin friction f = 3.6 kPa (1-7.5m);30 kPa (9m-

13.5m)

(Equation 2.12 &

2.14)


=

34986 kPa ≤6800 kPa ≤11000 kPa

6800 kPa

(Equation 2.17)





95



Site

: Manikgonj Pile ID : PC-8B P-134 Pile sec : 0.3mX0.3m Length : 13.72m


Soil Depth


1.5 1

Silt 3 1

4.5 2

6 2 2

7.5 6

9 8

10.5 11

Sand 12 15 13

13.5 17



Unit skin friction f = 4.08 kPa (silt);25.50 kPa (sand) (Equation 2.15 &

2.14)


=

31098 kPa ≤6800 kPa ≤11000 kPa

6800 kPa

(Equation 2.16)





96



Site



Soil Depth


1.5 1

Silt 3 1

4.5 2

6 2 2

7.5 6

9 8

10.5 11

Sand 12 15 13

13.5 17




2.14)


=

32928 kPa ≤7200 kPa ≤11000 kPa

7200 kPa

(Equation 2.16)





97



Site



Soil Depth


1.5 4

Silt 3 4

4.5 1

6 2 3

7.5 4

9 8

10.5 12

Sand 12 14 13

13.5 17




2.14)


=

31098 kPa ≤6800 kPa ≤11000 kPa

6800 kPa

(Equation 2.16)





98



Site



Soil Depth


1.5 3

Silt 3 3

4.5 10

6 7 6

7.5 8

9 20

Silty 10.5 8

Sand 12 14 15

13.5 15

15 18

16.5 14




2.14)


=

19392 kPa ≤4200 kPa ≤11000 kPa

4200 kPa

(Equation 2.16)





99



Site



Soil Depth


1.5 4

ML 3 2

4.5 8

6 4 5

7.5 8

9 17

10.5 14

SM 12 18 17

13.5 16

15 20

16.5 15




2.14)


=

20777 kPa ≤4500 kPa ≤11000 kPa

4500 kPa

(Equation 2.16)





100



Site



Soil Depth


1.5 2

Silt 3 5

4.5 9

6 10 15

7.5 16

9 20

10.5 22

Sand 12 22

13.5 25





=

45667 kPa ≤10000 kPa ≤11000 kPa

10000 kPa

(Equation 2.16)





101



Site



Soil Depth


1.5 5

Silt 3 7 6

4.5 9

6 10 12

7.5 11

9 16

10.5 14

Sand 12 10

13.5 13



Unit skin friction f = 10.20 kPa (silt), 23.71 kPa(sand) (Equation 2.15 &

2.14)


=

23747 kPa ≤5200 kPa ≤11000 kPa

5200 kPa

(Equation 2.16)





102



Site

: Keranigonj Pile ID : TP -2 Pile sec : 0.3mX0.3m Length : 12m


Soil Depth


1.5 6

3 6

4.5 5

Silt 6 7 8

7.5 8

9 16

10.5 17

Sand 12 17

13.5 19 18

15 20



Unit skin friction f = 13.60 kPa (silt), 36.50 kPa(sand) (Equation 2.15 &

2.14)


=

36533 kPa ≤8000 kPa ≤11000 kPa

8000 kPa

(Equation 2.16)





103



Site



Soil Depth


1.5 4

3 2

4.5 5

Sand 6 10 14

7.5 25

9 19

10.5 20

12 26



Unit skin friction f = 27.75 kPa(sand) (Equation 2.14)


=

41600 kPa ≤10400 kPa ≤11000 kPa

10400 kPa

(Equation 2.16)





104



Site



Soil Depth


1.5 1

3 3

Silt 4.5 3

6 5 3

7.5 5

9 6

10.5 16

Sand 12 5 11

13.5 24



Unit skin friction f = 5.10kPa (silt),22.40 kPa(sand) (Equation 2.14 &

2.15)


=

38400 kPa ≤9600 kPa ≤11000 kPa

9600 kPa

(Equation 2.16)





105



Site



Soil Depth


1.5 4

silt 3 2

4.5 5

6 10 5

7.5 25

9 19

10.5 20 24

Sand 12 26

13.5 32



Unit skin friction f = 8.93kPa (silt),48.40 kPa(sand) (Equation 2.14 &

2.15)


=

57600 kPa ≤12800 kPa ≤11000 kPa

11000 kPa

(Equation 2.16)





106



Site

: Borguna Pile ID : P-106 Pile sec : 0.35mX0.35m Length : 16.7m


Soil Depth


1.5 1

3 1

4.5 2

6 2 8

7.5 4

9 8

10.5 11

Silty 12 11

Sand 13.5 14

15 14

16.5 17



Unit skin friction f = 13.14 kPa(sand) (Equation 2.15)


=

24334 kPa ≤6800 kPa ≤11000 kPa

6800 kPa

(Equation 2.16)





107

APPENDIX D

CAPACITY CALCULATION OF BORED PILES

(BNBC 2015 AND AASHTO 2002 METHOD)

108

SL No : 1 (Bored pile) Method


Site

: Walton Office, Basundhara, Dhaka Pile ID : TP-01 Pile diameter : 0.5m Length : 28.5m


Soil Depth


1.5 6 3 4 4.5 8

Clay 6 7 7.5 2 9.1 9 12 10.5 7 12 21 13.5 15 15 19

Sand 16.5 20 23 18 24 19.5 24 21 26 22.5 26 24 25 25.5 25 27 24 28.5 24

Unit skin friction f = 10.93 kPa(Clay), 22.75 kPa (Sand) (Equation 2.24 & 2.26)



=

21375 kPa ≤ 3750 kPa ≤4000 kPa

3750 kPa

(Equation 2.28)




109



Site

: Titas Railway Bridge, Akhaura Pile ID : Pile No-19 Pile diameter : 1.2 m Length : 30.8m


Soil Depth


1.5 1 Silt 3 1 1

4.5 1 Clay 6 1 2

7.5 4 9 4 10.5 17 12 10 13.5 17 15 22

Silt 16.5 6 18 6 19.5 19 18 21 15 22.5 28 24 19 25.5 27 27 26 28.5 26 30 26

Unit skin friction f = 0.9 kPa(Sand), 2.40 kPa (Clay),16.08 kPa

(Silt)

(Equation

2.26,2.24 & 2.27)



=

6673 kPa ≤ 3900 kPa ≤4000 kPa

3900 kPa

(Equation 2.27)




110



Site

: Padma Bridge, Naodoba, Zazira Pile ID : Bridge 01 Abutment 02 Pile diameter : 1.2 m Length : 29.5m


Soil Depth


1.5 2 3 7 4.5 6 6 12 7.5 10 9 8 10.5 8

Silty 12 9 12 Sand 13.5 18

15 7 16.5 11 18 15 19.5 18 21 10 22.5 16 24 16 25.5 24 27 24




=

5900 kPa ≤ 2400 kPa ≤4000 kPa

2400 kPa

(Equation 2.29)




111



Site

: Mogbazar Fly over, Dhaka Pile ID : TP-2 Pile diameter : 1.2 m Length : 29.5m


Soil Depth


2 15

Clay 6 12 13

8 11

10 12

12 19

14 20

16 23

18 20 22.4

Sand 20 22

22 27

24 30

27 29

30 22

Unit skin friction f = 15.20 kPa (Clay), 20.16 kPa(Silt) (Equation 2.24&

2.27)



=

8112 kPa ≤ 3300 kPa ≤4000 kPa

3300 kPa

(Equation 2.28)




112

SL No

:

5 (Bored pile)

Method


Site

: Mogbazar Fly over, Dhaka Pile ID : P-114 Pile diameter : 1.5 m Length : 44m


Soil Depth


2 15

Clay 6 12 13

8 11

10 12

12 19

14 20

16 23

18 20 24

Sand 20 22

22 27

24 30

27 29

30 22

33 28

37 28

40 27

44 27

Unit skin friction f = 15.20 kPa (Clay), 21.47 kPa(Silt) (Equation 2.24& 2.27)



=

11880 kPa ≤ 4050 kPa ≤4000 kPa

4000 kPa

(Equation 2.28)




113

SL No

:

6 (Bored pile)

Method


Site



Soil Depth


2 15

Clay 6 12 13

8 11

10 12

12 19

14 20

16 23

18 20 24

Sand 20 22

22 27

24 30

27 29

30 22

33 28

37 28

40 27

44 27




=

14850 kPa ≤ 4050 kPa ≤4000 kPa

4000 kPa

(Equation 2.28)




114

SL No

:

7 (Bored pile)

Method


Site

: Dhaka Road Research Lab Pile ID : P1 Pile diameter : 1.2 m Length : 44m


Soil Depth


1.5 7

3 12 11

Clay 4.5 7

6 13

7.5 16

9 27

10.5 26

12 19 21

Sand 13.5 23

15 22

16.5 22

18 23

19.5 21

21 12

22.5 14




=

4725 kPa ≤ 2100 kPa ≤4000 kPa

2100 kPa

(Equation 2.28)




115

SL No

:

8 (Bored pile)

Method


Site

: Dhaka Road Research Lab Pile ID : P2 Pile diameter : 1.2 m Length

: 44m Soil Profile and properties Bore Hole Data of BH-1

Soil Depth


1.5 7 3 12 11

Clay 4.5 7 6 13 7.5 16 9 27 10.5 26 12 19 22

Sand 13.5 23 15 22 16.5 22 18 23 19.5 21 21 12 22.5 14 24 24 25.5 27 27 26 28.5 26




=

10920 kPa ≤ 3900 kPa ≤4000 kPa

3900 kPa

(Equation 2.28)




116

SL No

:

9 (Bored pile)

Method


Site

: Zinzira-Nawabganj (Bridge LRP) Pile ID : P3 Pile diameter : 1 m Length : 23.7m


Soil Depth

(m) SPT

𝐍𝟔𝟎

1.5 5 Clay 3 11 6

4.5 3 6 5 7.5 7 9 6 10.5 23

12 25 26.8

Sand 13.5 24 15 31 16.5 24 18 29 19.5 29 21 28 22.5 28 24 27 25.5 27




=

9599 kPa ≤ 4050 kPa ≤4000 kPa

4000 kPa

(Equation 2.28)




117

SL No

:

10 (Bored pile)

Method


Site



Soil Depth


1.5 3 Clay 3 2 6

4.5 4 6 4 7.5 8 9 15 10.5 20

12 21 22

Sand 13.5 24 15 22 16.5 23 18 17 19.5 24 21 22 22.5 20 24 27 25.5 27




=

8100 kPa ≤ 4050 kPa ≤4000 kPa

4000 kPa

(Equation 2.28)




118


: α and β method (BNBC-2015)

Site


Soil Profile and properties

Bore Hole Data of BH-2

Adhesion factor α= 0.55 (Table 2.2)

Effective vertical stress σ = 162.86 kpa ( mid soil layer)

Friction factor for overburden β = 0.35 (Equation 2.23)

Skin friction f = 1.00 kpa (Clay), 55.12 kpa (Sand-1), 57.09 (Sand-2)

Total skin friction Q = 1275 kN (Equation 2.2)

Unit end bearing f = 27.30 kpa (Table 2.3)

Tip resistance Q = 294 kN [Q = qb

X Area of pile]


Total capacity Q = 1435 kN (Equation 2.1)

SoilDepth

(m)SPT γ Su(kpa)

z (m)

1.5 63 4

4.5 8Clay 6 7 17.3 1.8 6

7.5 29 12

10.5 712 21

13.5 1515 19

Sand 16.5 2018 24 17.3 22

19.5 2421 26

22.5 2624 25

25.5 2527 24

28.5 24

119

SL No

:

2 (Bored pile)

Method


Site

: Titas Railway Bridge, Akhaura Pile ID : Pile No-19 Pile diameter : 1.2 m Length : 30.8m




Friction factor for overburden β= 1.20 (1-3m),0.41 (9-30.8m) (Equation 2.23)

Skin friction f = 13.46 kpa (1-3m), 19.15 kpa(3-7.5m),55.48 kpa (7.5

-30.8m)


Unit end bearing f = 1620 kpa (Table 2.3)


X Area of pile]


Total capacity Q = 6016 kN (Equation 2.1)

SoilDepth

(m)SPT γ

Su kpa

z (m)

1.5 1Silt 3 1 17 1.5

4.5 1Clay 6 1 17 19.2

7.5 49 4

10.5 1712 10

13.5 1715 22

Silt 16.5 618 6

19.5 19 17 19.521 15

22.5 2824 19

25.5 2727 26

28.5 2630 26

120

SL No

:

3 (Bored pile)

Method


Site






Friction factor for overburden β= 0.59 (Equation 2.23)

Skin friction f = 60.09 kpa



Tip resistance Q = 1628 kN [Q = qb X Area of pile]



Soil Depth (m) SPT γ z (m)

1.5 23 7

4.5 66 12

7.5 109 8

10.5 8Silty 12 9Sand 13.5 18 17.29 13.5

15 716.5 1118 15

19.5 1821 10

22.5 1624 16

25.5 2427 24

121



Site





Effective vertical

stress

σ = 149.76 kpa ( mid soil layer)

Friction factor for

overburden

β= 0.40 (Equation 2.23)

Skin friction f = 46.09 kpa (Clay), 53.61 (Sand)






SoilDepth

(m)SPT γ

Su kpa

z (m)

2 15

Clay 6 12 17.3 121 4

8 11

10 12

12 19

14 20

16 23

18 20

Sand 20 22 17.3 20

22 27

24 30

27 29

30 22

122



Site





Friction factor for

overburden

β= 0.30 (Equation 2.23)







SoilDepth

(m)SPT γ

Su (kpa)

z (m)

2 15

Clay 6 12 17.3 121.3 4

8 11

10 12

12 19

14 20

16 23

18 20

Sand 20 22

22 27

24 30 17.3 25

27 29

30 22

33 28

37 28

40 27

44 27

123


: α and β method (BNBC-2015) : Site





Effective vertical

stress

σ = 187.20 kpa ( mid soil layer)

Friction factor for

overburden

β= 0.27 (Equation 2.23)







SoilDepth

(m)SPT γ

Su kpa

z (m)

2 15Clay 6 12 17.3 121 4

8 1110 1212 1914 2016 2318 20

Sand 20 2222 2724 30 17.3 2527 2930 2233 2837 2840 2744 27

124



Site












SoilDepth

(m)SPT γ

Su kpa

z (m)

1.5 73 12 17 105 4.5

Clay 4.5 76 13

7.5 169 27

10.5 2612 19

Sand 13.5 23 17 1515 22

16.5 2218 23

19.5 2121 12

22.5 14

125

SL No

:

8 (Bored pile)

Method


Site












SoilDepth

(m)SPT γ

Su kpa

z (m)

1.5 73 12 17.3 105 4.5

Clay 4.5 76 13

7.5 169 27

10.5 2612 19

Sand 13.5 23 17.3 1815 22

16.5 2218 23

19.5 2121 12

22.5 1424 24

25.5 2727 26

28.5 26

126



Site

: Zinzira-Nawabganj (Bridge LRP) Pile ID : P3 Pile diameter : 1 m Length m

: 23.7m









X Area of pile]



SoilDepth

(m) SPT γSu kpa

z (m)

1.5 53 11 17 59.1 4.5

Clay 4.5 36 5

7.5 79 6

10.5 2312 25

Sand 13.5 24 17 1715 31

16.5 2418 29

19.5 2921 28

22.5 2824 27

25.5 27

127

SL No

:

10 (Bored pile)

Method


Site










X Area of pile]



SoilDepth

(m) SPT γSu

kpaz

(m)1.5 33 2 17 57.5 4.5

Clay 4.5 46 4

7.5 89 15

10.5 2012 21

Sand 13.5 24 17 1715 22

16.5 2318 17

19.5 2421 22

22.5 2024 27

25.5 27

128


: AASHTO(2002)

Site




Un-drained shear

strength

s = 1.31 ksf [N(avg)/5]

Skin friction Q =

=

93.06 kip(Clay)+ 356.53 kip (Sand)

449.59 kip

(Equation 2.31 &

2.32)

Unit end bearing q = 27.30 ksf (Table 2.3)

Tip resistance Q = 59.53 kip Q = q X Area of pile

Weight of pile W= 30.18 kip

Total capacity Q = 478.94 kip (Equation 2.30)

2130 kN

Soil SPT Zi (ft)γ'

lb/cftγ'Zi (ksf)

βi

6 4.924 9.84 47.608 14.76

Clay 7 19.682 24.6

12 29.527 34.44

21 39.36 47.60 1.87 0.6515 44.28 2.11 0.6019 49.2 2.34 0.55

Sand 20 54.12 2.58 0.5124 59.04 2.81 0.4624 63.96 3.04 0.4226 68.88 3.28 0.3826 73.8 3.51 0.3425 78.72 3.75 0.3025 83.64 3.98 0.2724 88.56 4.22 0.2324 93.48 4.45 0.19

129


: AASHTO(2002)

Site

: Titas Railway Bridge, Akhaura

Pile ID : Pile No-19 Pile diameter : 1.2 m Length : 30.8m



Un-drained shear

strength

s = 0.4 ksf [N(avg)/5]

Skin friction Q =

=

27.17 kip(Clay)+ 1011.77 kip (Sand)

1038.96 kip

(Equation 2.31 &

2.32)





4983 kN

Soil SPT Zi (ft)γ'

lb/cftγ'Zi (ksf)

βi

1 4.92Silt 1 9.84 47.60

1 14.76 0.70 0.981Clay 1 19.68 0.94 0.90

4 24.6 1.17 0.834 29.52 1.41 0.7717 34.44 1.64 0.7110 39.36 47.60 1.87 0.6517 44.28 2.11 0.6022 49.2 2.34 0.55

Silt 6 54.12 2.58 0.516 59.04 2.81 0.4619 63.96 3.04 0.4215 68.88 3.28 0.3828 73.8 3.51 0.3419 78.72 3.75 0.3027 83.64 3.98 0.2726 88.56 4.22 0.2326 93.48 4.45 0.1926 98.4 4.68 0.16

130


: AASHTO(2002)

Site



Adhesion factor α = 0.55 (Table 2.2)

Un-drained shear

strength

s = 0.4 ksf [N(avg)/5]

Skin friction Q = 1101.81 kip (Equation 2.32)





4924 kN

Soil SPTZi

(ft)γ'

lb/cftγ'Zi (ksf)

βi

2 4.92 0.23 1.207 9.84 0.47 1.086 14.8 0.70 0.9812 19.7 0.94 0.9010 24.6 1.17 0.838 29.5 1.41 0.77

Silty 8 34.4 1.64 0.71Sand 9 39.4 47.60 1.87 0.65

18 44.3 2.11 0.607 49.2 2.34 0.5511 54.1 2.58 0.5115 59 2.81 0.4618 64 3.04 0.4210 68.9 3.28 0.3816 73.8 3.51 0.3416 78.7 3.75 0.3024 83.6 3.98 0.2724 88.6 0.00 0.23

131


: AASHTO(2002)

Site




Un-drained shear

strength

s = 2.53 ksf [N(avg)/5]

Skin friction Q =

=

373.11 kip (Clay)+892 kip (Sand)

1265 kip

(Equation 2.31 &

2.32)

Unit end bearing q = 27 ksf (Table 2.3)

Tip resistance Q = 338 kip Q = q X Area of pile


Total capacity Q = 1423 kip (Equation 2.30)

6328 kN

Soil SPTZi

(ft)γ'

lb/cftγ'Zi (ksf)

βi

15 6.56

Clay 12 19.7 47.60

11 26.2

12 32.8 1.56 0.73

19 39.4 1.87 0.65

20 45.9 2.19 0.59

23 52.5 2.50 0.52

Sand 20 59 47.60 2.81 0.46

22 65.6 3.12 0.41

27 72.2 3.43 0.35

30 78.7 3.75 0.30

29 88.6 4.22 0.23

22 98.4 4.68 0.16

132


: AASHTO(2002)

Site




Un-drained shear

strength

s = 2.53 ksf [N(avg)/5]

Skin friction Q =

=

574 kip (Clay)+1452 kip (Sand)

2026 kip

(Equation 2.31 & 2.32)



Weight of pile W= 130 kip


10936 kN

Soil SPTZi

(ft)γ'

lb/cftγ'Zi (ksf)

βi

15 6.56

Clay 12 19.7 47.60

11 26.2

12 32.8 1.56 0.73

19 39.4 1.87 0.65

20 45.9 2.19 0.59

23 52.5 2.50 0.52

Sand 20 59 47.60 2.81 0.46

22 65.6 3.12 0.41

27 72.2 3.43 0.35

30 78.7 3.75 0.30

29 88.6 4.22 0.23

22 98.4 4.68 0.16

28 108 5.15 0.10

28 121 5.78 0.01

27 131 6.25 0.00

27 144 6.87 0.00

133


: AASHTO(2002)

Site




Un-drained shear

strength

s = 2.53 ksf [N(avg)/5]

Skin friction Q =

=


1621 kip

(Equation 2.32)





8009 kN

Soil SPT Zi (ft)γ'

lb/cftγ'Zi (ksf)

βi

15 6.56Clay 12 19.68 47.60

11 26.2412 32.8 1.56 0.7319 39.36 1.87 0.6520 45.92 2.19 0.5923 52.48 2.50 0.52

Sand 20 59.04 47.60 2.81 0.4622 65.6 3.12 0.4127 72.16 3.43 0.3530 78.72 3.75 0.3029 88.56 4.22 0.2322 98.4 4.68 0.1628 108.24 5.15 0.1028 121.36 5.78 0.0127 131.2 6.25 0.0027 144.32 6.87 0.00

134


: AASHTO(2002)

Site




Un-drained shear strength s = 2.2 ksf [N(avg)/5]

Skin friction Q =

=


644 kip

(Equation 2.31 &

2.32)





3406 kN

Soil SPT Zi (ft)γ'

lb/cftγ'Zi (ksf)

βi

7 4.92

12 9.84 47.60

Clay 7 14.76

13 19.68

16 24.6

27 29.52

26 34.44 1.64 0.71

Sand 19 39.36 47.60 1.87 0.65

23 44.28 2.11 0.60

22 49.2 2.34 0.55

22 54.12 2.58 0.51

23 59.04 2.81 0.46

21 63.96 3.04 0.42

12 68.88 3.28 0.38

14 73.8 3.51 0.34

135


: AASHTO(2002)

Site




Un-drained shear

strength

s = 2.2 ksf [N(avg)/5]

Skin friction Q =

=


705 kip

(Equation 2.31 & 2.32)





3630 kN

Soil SPTZi

(ft)γ'

lb/cftγ'Zi (ksf) βi

7 4.9212 9.84 47.60

Clay 7 14.813 19.716 24.627 29.5 1.41 0.7726 34.4 1.64 0.71

Sand 19 39.4 47.60 1.87 0.6523 44.3 2.11 0.6022 49.2 2.34 0.5522 54.1 2.58 0.5123 59 2.81 0.4621 64 3.04 0.4212 68.9 3.28 0.3814 73.8 3.51 0.3424 78.7 0.00 0.3027 83.6 0.00 0.2726 88.6 0.00 0.2326 93.5 0.00 0.19

136


: AASHTO(2002)

Site




Un-drained shear

strength

s = 1.28 ksf [N(avg)/5]

Skin friction Q =

=


748 kip

(Equation 2.31 & 2.32)





3784 kN

Soil SPT Zi (ft)γ'

lb/cftγ'Zi (ksf)

βi

Rubish 5 4.9211 9.84 47.60

Clay 3 14.765 19.687 24.66 29.5223 34.44 1.64 0.71

Sand 25 39.36 47.60 1.87 0.6524 44.28 2.11 0.6031 49.2 2.34 0.5524 54.12 2.58 0.5129 59.04 2.81 0.4629 63.96 3.04 0.4228 68.88 3.28 0.3828 73.8 3.51 0.3427 78.72 3.75 0.3027 83.64 3.98 0.27

137


: AASHTO(2002)

Site




Un-drained shear

strength

s = 1.2 ksf [N(avg)/5]

Skin friction Q =

=


741 kip

(Equation 2.31 & 2.32)





3854 kN

Soil SPT Zi (ft)γ'

lb/cftγ'Zi (ksf)

βi

3 4.92Clay 2 9.84 47.60

4 14.764 19.688 24.615 29.5220 34.44 1.64 0.71

Sand 21 39.36 47.60 1.87 0.6524 44.28 2.11 0.6022 49.2 2.34 0.5523 54.12 2.58 0.5117 59.04 2.81 0.4624 63.96 3.04 0.4222 68.88 3.28 0.3820 73.8 3.51 0.3427 78.72 3.75 0.3027 83.64 3.98 0.27

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