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UNIVERSITI TEKNOLOGI MALAYSIA

BORANG PENGESAHAN STATUS TESIS

JUDUL : PREDICTION OF ULTIMATE LOAD BEARING CAPACITY OF DRIVEN PILES

SESI PENGAJIAN: 2006/2007

Saya WONG CHARNG CHEN _______________________

(HURUF BESAR)

mengaku membenarkan tesis (Psm/Sarjana/Doktor Flasafah)* ini disimpan di Perpustakaan

Universiti Teknologi Malaysia dengan syarat-syarat kegunaan seperti berikut :

Tesis adalah hakmilik Universiti Teknologi Malaysia.Perpustakaan Universiti Teknologi Malaysia dibenarkan membuat salinan untuk tujuan

pengajian sahaja.

Perpustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran antarainstitusi pengajian tinggi.

** Sila tandakan ( )

SULIT (Mengandungi maklumat yang berdarjah keselamatan ataukepentingan Malaysia seperti yang termaktub di dalamAKTA RAHSIA RASMI 1972)

TERHAD (Mengandungi maklumat TERHAD yang telah ditentukanoleh organisasi/badan di mana penyelidikan dijalankan)

TIDAK TERHAD

Disahkan oleh

__________________________________ ___________________________________

(TANDATANGAN PENULIS) (TANDATANGAN PENYELIA)

Alamat Tetap : Nama Penyelia:

No. 21, Jalan Punai, Assoc. Prof. Dr. Aminaton Marto

96100 Sarikei,

Sarawak.

Tarikh : 22 November 2006 Tarikh : 22 November 2006

.

CATATAN: * Potong yang tidak berkenaan.** Jika tesis ini SULIT atau TERHAD, sila lampirkan surat daripada pihak

berkuasa/organisasi berkenaan dengan menyatakan sekali sebab dan tempoh tesis iniperlu dikelaskan sebagai SULIT atau TERHAD.

Tesis dimaksudkan sebagai tesis bagi Ijazah Doktor Falsafah dan Sarjana secarapenyelidikan, atau disertasi bagi pengajian secara kerja kursus dan penyelidikan, atauLaporan Projek Sarjana Muda (PSM).


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I declare that I have read through this project report and to my opinion

this project report is sufficient in term of scope and quality for the purpose of

awarding the degree of Master of Engineering (Civil-Geotechnic)

Signature : ..

Name of Supervisor : Assoc. Prof. Dr. Aminaton Marto

Date : 22 November 2006


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PREDICTION OF ULTIMATE LOAD BEARING CAPACITY OF DRIVEN PILES

WONG CHARNG CHEN

A project report submitted in partial fulfillment

of the requirements for the award of the degree of

Master of Engineering (Civil Geotechnic)

Faculty of Civil Engineering

Universiti Teknologi Malaysia

NOVEMBER 2006


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I declare that this project report entitled Prediction of Ultimate Load Bearing

Capacity of Driven Piles is the result of my own work except as cited in the

references. The report has not been accepted for any degree and is not currently

submitted in candidature of any other degree.

Signature : ..

Name : Wong Charng Chen

Date : 22 November 2006


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To my beloved family members

And all of my friends in UTM and KUiTTHO


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vi

ABSTRAK

Adalah susah bagi seseorang jurutera untuk memastikan rekaan asas

cerucuknya secara teori adalah sama dengan keadaan di tapak disebabkan oleh

perbezaan lapisan tanah. Oleh itu, setiap rekaan asas cerucuk mempunyai

ketidakpastian dan risiko yang tersendiri. Projek ini dijalankan untuk menilai

kesesuaian lapan jenis kaedah menentukan keupayaan muktamad cerucuk geseran

terpacu terputar. Analisis dan penilaian telah dijalankan ke atas empat cerucuk

terputar yang berlainan saiz dan panjang dan telah gagal dalam ujian beban. Kaedah

interpretasi ujian beban, formula-formula penanaman cerucuk dan kaedah Meyerhof

(analisis statik) telah diguna untuk menentukan keupayaan muktamad (Qp) cerucuk

berkaitan. Beban gagal merupakan beban maksimum (Qm) yang telah diukur semasa

ujian beban dijalankan. Nilai yang ditentukan oleh kaedah-kaedah yang dinyatakan

telah dibandingkan dengan beban maksimum yang telah diukur dari ujian beban.

Tiga jenis kaedah penilaian telah dikenalpasti iaitu: garisan lurus terbaik untuk Qp

melawan Qm, pengiraan purata dan taburan normal piawai untuk nisbah Qp/Qm dan

kebarangkalian kumulatif untuk Qp/Qm. Keputusan analisis menunjukkan kaedah

Butler and Hoy (kaedah interpretasi ujian beban) merupakan kaedah paling baik.

Kaedah ini terletak pada tahap nombor satu mengikut kriteria yang dinyatakan.


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TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES xi

LIST OF FIGURES xii

LIST OF SYMBOLS xiv

LIST OF APPENDICES xvi

1 INTRODUCTION 1

1.1 Background of the study 1

1.2 Objectives 2

1.3 Scope of study 3

1.4 Importance of study 4

2 LITERATURE REVIEW 5

2.1 Foundations on Problematic Soils 5

2.2 Deep Foundations 6

2.2.1 Driven Piles 7

2.2.2 Changes in Cohesive Soils 7

2.2.3 Changes in Granular Soils 8

2.3 Pile Load Testing 9


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2.7.2 Engineering News Record (ENR) Formula 34

2.8 Failure in Foundation Engineering 36

2.8.1 Strength Requirement 37

2.8.1.1 Geotechnical Strength Requirements 37

2.8.1.2 Structural Strength Requirements 37

2.8.2 Serviceability Requirements 37

2.8.2.1 Settlement 38

2.8.2.2 Heave 39

2.8.2.3 Tilt 40

2.8.2.4 Lateral Movement 40

2.8.2.5 Durability (Corrosion) 40

3 METHODOLOGY 42

3.1 Introduction 42

3.2 Data Collection 42

3.3 Compilation of Data 43

3.3.1 Soil Data 44

3.3.2 SPT Data 44

3.3.3 Piling Records 44

3.3.4 Pile Load Tests Reports 44

3.4 Data Analysis 45

3.5 Comparison of the Results 45

3.6 Evaluation of Methods 46

3.6.1 Best Fit Line Equation 46

3.6.2 Cumulative Probability 47

3.6.3 Mean () and Standard Deviation ()

of Qp/Qm 48

3.7 Conclusion and Recommendation 49

4 CASE STUDY 50

4.1 Location of Study 50

4.2 Piled Foundations 52

4.3 Static Pile Load Test 534.4 Pile Instrumentation 53


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LIST OF FIGURES

FIGURE NO. TITLE PAGE

2.1 Load settlement curve 10

2.2 Load-movement curve of Davissons Method 14

2.3 Load-movement curve of Chins Method 152.4 Load-movement curve of De Beers Method 16

2.5 Load-movement curve of Brinch Hansens 80 Percent

Criterion 17

2.6 Load-movement curve of Mazurkiewiczs Method 19

2.7 Load-movement curve of Fuller and Hoys, and Butler and

Hoys Method 19

2.8 Critical embedment ratio and bearing capacity factors for

various soil friction angles 21

2.9 Variation of bearing capacity factor, Nq and earth pressure

coefficient, K with L/D 22

2.10 Variation of with undrained cohesion of clay 26

2.11 Variation ofwith pile embedment length 27

3.1 Methodology flow chart 43

3.2 Best fit line 47

3.3 Cumulative probability curve 48

4.1 Site location plan 51

4.2 Site geological cross-section 51

4.3 Instrumentation details for static axial compression load tests 54

4.4 Typical static axial compression load tests setup 55

5.1 Comparison of measured and predicted pile capacity (Chin) 58

5.2 Comparison of measured and predicted pile capacity

(Brinch Hansen) 58


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ranked number according to mentioned criteria is considered as the most accurate

method and is recommended for pile design practice.

1.4 Importance of Study

Static analysis formulae and pile driving formulae are not recommended as

the sole means of determining the acceptability of a pile, except on small jobs

(Fleming, 1985). These analyses do not describe the complex mechanics of pile

driving in rational way and interaction between pile and the surrounding soil is

poorly modeled. Thus, it is important to determine accuracy from these formulae

through comparison with actual bearing capacity from site. The differences can be

used as a guideline when pile load tests are not able to be conducted.

The problems with many of the interpretation methods are that they are either

empirical methods or are based on set deformation criteria. Several methods are also

sensitive to the shape of the load-settlement curve and it is preferable to use a

considerable number of load increment to define the shape clearly; for example,

Chins Method assumes the load-deformation curve is hyperbolic and is an empirical

method. An engineer may have difficulty in choosing the best method to interpret

the static load test data. This study is able to help an engineer to identify the

suitability of the proposed interpretation methods to predict the ultimate bearing

capacity of spun piles driven to set. Moreover, through the analyses, the most

appropriate method is identified.


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CHAPTER 2

LITERATURE REVIEW

2.1 Foundations on Problematic Soils

The most common of these problematic soils are the soft, saturated clays and

silts often found near the mouths of rivers, along the perimeter of bays, and beneath

wetlands. These soils are very weak and compressible, and thus are subject to

bearing capacity and settlement problems. These soils also frequently include

organic material in which will aggravate these problems.

Areas underlain by soft soils frequently below mean sea level, and thus are

subjected to flooding. Therefore, it is necessary to raise the ground by placing fill.

However, the weight of the fill frequently causes large settlement. For example,

Scheil (1979) described a building constructed on fill underlain by varved clay in the

Hackensack Meadowlands of New Jersey. About 250 mm of settlement occurred

during placement of the fill, 12 mm during construction of the building, and anadditional 100 mm over the following ten years.

In seismic areas, loose saturated sands can become weak through the process

of liquefaction. Moderate to strong ground shaking can create large excess pore

water pressures in these soils, which temporarily decrease the effective stress and

shear strength. Seed (1970) described the phenomenon occurred in Niigata, Japan

during 1964 earthquake. Many buildings settled more than 1 m, and thesesettlements were often accompanied by severe tilting.


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However, engineers have developed several methods to alleviate the effects

of problematic soils which include supporting the structure on deep foundations that

penetrate through the weak soils.

2.2 Deep Foundations

Deep foundations are usually referred to as pile foundations. Piles are

relatively long and generally slender structural foundation members that transfer load

to lower levels of the ground which are capable of sustaining it with an adequate

factor of safety and without settling under normal working conditions by an amount

detrimental to the structure. In geotechnical engineering, piles usually serve as

foundations when soil conditions are not suitable for the use of shallow foundations.

Moreover, piles have other applications in deep excavations and in slope stability

such as they can be installed to form retaining walls.

There are many types of pile in use today, with varying geometry which

depends upon imposed loading and soil conditions. Generally, piles are classified

according to the nature of load support (friction and end-bearing piles), the

displacement properties (full-displacement, partial-displacement, and non-

displacement piles), and the composition of piles (timber, concrete, steel, and

composite piles). The choice of pile for a particular job depends upon the

combination of all the various soil conditions and the magnitude of the applied load.

Besides its technical aspects, economical factor should also be a consideration.

The behavior of the pile depends on many different factors, including pile

characteristics, soil conditions and properties, installation method, and loading

conditions. The performance of piles affects the serviceability of the structure they

supported. In this study, only driven piles (displacement piles) are discussed.


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2.3 Pile Load Testing

Pile load testing in Malaysia is normally based on the specification developed

by Jabatan Kerja Raya (JKR), Malaysia. Pile load test is carried out to determine the

relationship between load and settlement. It is to ensure the failure does not occur

before the ultimate design load has been reached. Pile load test also being carried

out with the purpose of determine the ultimate bearing capacity of the pile and so

define the maximum design factor of safety. Finally, pile load test can be used to

check the workmanship of any randomly selected pile is satisfactory.

The pile load test program should be considered as part of the design andconstruction process, and not carried hurriedly in response to an immediate

construction problem (Fleming, 1985). Pile tests may be performed at various stages

of construction, i.e. prior to construction and during construction. A large amount of

information can be obtained from properly planned tests. This useful information

may lead to refinement of the foundation design with consequent possible cost

saving and certainly greater assurance of the satisfactory performance of the

foundation.

Three types of tests have been recommended by the JKR, namely Maintained

Load Test (ML Test), Constant Rate of Penetration Test (CRP Test) and Pile Driving

Analyzer (PDA). These tests are performed based on the JKR specification or BS

8004. The standard procedures are explained in the later part of the report.

The period of time which the test should be carried out in various soils is

mentioned by Bowles (1996). Piles in granular soil are often tested 24 to 48 hrs after

driving when load arrangements have been made. This time lapse is sufficient for

excess pore water pressure to dissipate. Pile in cohesive soils should be tested after

sufficient lapse for excess pore water pressure to dissipate. This time lapse is

commonly in the duration of 30 to 90 days in order for cohesive soil to gain some

additional strength from thixotropic effects.


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2.3.2 Advantages of Static Load Test

According to Han (1999), the static test is considered as the reference test

because it is the one that corresponds the most with the way that the load is applied

in reality (duration, loading rate and type of loading). The static test is generally

regarded as the definitive test against which other types of tests are compared. These

elements are obviously the best advantages of this kind of tests.

The data obtained are directly interpretable because they are linked to the

acceptance criteria (maximum settlement and authorized stiffness and/or design

load). Another reason is that the main interpretations were created with respect to

this kind of test. As such, all the other methods tried to predict response comparable

to the load settlement produced by the static load test. Finally, the measurements are

generally independent of the pile material properties.

2.3.3 Disadvantages of Static Load Test

Since the static load test is very closely related to the reality, the time needed

to carry out is relatively long (Han, 1999). This duration is costly in term of money

and contract planning. Besides, to create the actual condition of loading slow

loading rate is imposed. The load is applied high enough to get closer to the real

load to be applied to the foundation. So the mobilization of this load and of this

associated reaction is strongly expensive regarding to the obtained result (one pile

tested).

The reaction supplied for the applied loading (kentledge, reaction piles,

ground anchors) generates some associated effects or interaction with pile that

perturb the interpretation of the results. These stresses will increase the shaft friction

and the base capacity. The pile settlement is reduced and the pile head stiffness is

also overestimated.


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where 1/ C1 is the gradient of the slope. The relationships given in the Figure 2.3

assume that the load movement curve is approximately hyperbolic.

Figure 2.3 Load-movement curve of Chins Method (Nor Azizi, 2003)

This method of ultimate load interpretation is applicable for both the QM and

SM tests, provided that the constant time increments are used during the test. In

selecting the straight line from the points, it should be understood that the data points

do not appear to fall on the straight line. This method may not provide realistic

failure for tests carried out as per ASTM Standard Method because it may not have

constant time load increments.

Tolosko (1999) conducted the comparison on predicted ultimate bearing

capacity of 63 piles with the designated bearing capacity from static analysis. The

average ratio of Chins Method and designated bearing capacity is 1.69. This

indicates that Chins Method overpredicted the bearing capacity by more than 50

percent.

2.4.3 De Beers Method

De Beers Method or De Beers Log-Log Method was first introduced in

1971 (Tolosko, 1999). As seen in Figure 2.4, this method consists of the following


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steps. Load and movement is drawn on logarithmic scales. These values then will

fall on two straight lines. The predicted failure load, Qp is then defined as the load

that falls at the intersection of these two straight lines (De Beer, 1971). This method

was originally proposed for maintained load test, such as SM and QM test.

Figure 2.4 Load-movement curve of De Beers Method (Nor Azizi, 2003)

Tolosko (1999) has suggested that De Beers Method generally

underpredicted the designated bearing capacity of piles by 0.2. Bachand (1997)

concluded that the two slopes are especially visible for piles that experienced

plunging failure, yet on piles that undergone local failure, the results may be a range

of values.

2.4.4 Brinch Hansens 80 Percent Criterion

In 1963, Brinch and Hansen developed a method in which failure is obtained

based on assumption that hyperbolic relationship exists between the load and the

displacement (Tolosko, 1999). This method of interpretation is shown in Figure 2.5

and consists of the following steps. ThevaQ

and curve is drawn, where is the

settlement and Qva is the load. Predicted failure load ,Qp and failure movement u arethen given as follows:


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2.4.5 Mazurkiewiczs Method

Mazurkiewicz proposed his method on prediction of ultimate bearing

capacity of pile in 1972 (Spronken, 1998). As shown in Figure 2.6, this method

consists of the following steps. The load-movement curve is drawn. A series of

equal pile head movement is chosen and vertical lines that intersect on the curve is

drawn. Then horizontal line from these intersection points is drawn on curve to

intersect the load axis. From the intersection of each load, 45 line is drawn to

intersect with the next load line. These intersections will fall approximately on a

straight line. The point which is obtained by the intersection of the extension of the

line on the vertical (load) axis is predicted failure load, Qp.

This method assumes that load-movement curve is approximately parabolic.

The failure load values obtained by these method should be therefore be close to the

Brinch Hansen 80 percent criterion (Spronken, 1998). Furthermore, all the

intersections of these lines do not always fall on straight line. Therefore, some

judgment may be required in drawing the straight line.

2.4.6 Fuller and Hoys Method

Fuller and Hoys Method or also known as single tangent method was first

proposed in 1976 (Spronken, 1998). This method consists of the following steps. A

load-movement curve is drawn as shown in Figure 2.7. The predicted failure load Qp

on the curve is determined where the tangent on the load-movement curve is sloping

at 0.1 mm/kN.

This method is applicable for QM and SM test. The main disadvantage with

this method may be that it penalizes the long piles because they will have larger

elastic movements and therefore 0.1 mm/kN slope will occur sooner (Spronken,

1998).


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Coyle and Castello (1981) correlated that earth pressure coefficient, K with

embedment ratio (L/D) and friction angle () of the soil as shown in Figure 2.9.

This chart is designed based on assumptions that

= 0.8.

Broms (1965) suggested the values for K in granular soils as in Table 2.1

while Aas (1966) proposed the values of

as in Table 2.2:

Table 2.1 : Values for earth pressure coefficient, K in granular soils (Broms, 1965)

Type of Pile Loose Sand Dense Sand

Steel 0.5 1.0

Concrete 1.0 2.0

Timber 1.5 3.0

Table 2.2 : Values of soil-pile friction angle,

in different types of piles

(Aas, 1966)

Type of Pile Soil-Pile friction angle,

Steel 20

Concrete 0.75

Timber 0.66

Note : is the friction angle of soil

2.5.3 Load Carrying Capacity at Pile Point, Qt in Cohesive Soils (Meyerhof

Method)

The procedure for estimation of the point bearing capacity of a pile in

cohesive soil is similar as in granular soil. However, the equation for estimating load

carrying capacity at pile point, Qt = Ap(cNc + vNq) where c is cohesion of the soil

supporting the pile tip and Nc is bearing capacity factor. Nc is also obtained through

Figure 2.8.


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For piles in saturated clays in undrained condition ( = 0),

put AcQ 9= (2.6)

where cu is undrained cohesion of the soil below the pile tip.

2.5.4 Skin Resistance, Qs in Cohesive Soils

The equation favpL is generally accepted by most of the researchers.However, the proposed procedure to obtain unit skin friction (fav) is different from

one researcher to another researcher.

Tomlinson (1967) suggested a method known as method to estimate the

skin resistance in clayey soils. According to this method, the unit skin resistance can

be represented by the equation

ucf = (2.7)

where is empirical adhesion factor.

The approximate variation of the value of is shown in Figure 2.10. For

normally consolidated clays with cu is about 50 kN/m2

, is equal to one. Thus, skin

resistance is pLcQ us = .

Flaate (1968), after a comprehensive analysis on a number of pile loading

tests suggested that depended not only on the average undrained shear strength of

the clay, but also on the plasticity index.


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There is a weakness in this method in which the overburden stress is not

allowed to be greater than 95.6 kN/m2. Therefore, some other researchers have come

out with other formula. Liao and Whitman (1986) recommended that CN =

v'178.9

while Skempton (1986) porposed CN =v

,01.012

+.

For granular soils, the corrected N-value can be used to estimate the effective

friction angle of the soil,. Wolff (1989), based on research by Peck, Hanson and

Thornburn in 1974 has produced an empirical formula to correlate friction angle with

Ncor. The formula is shown as:

200054.03.01.27 corcor NN += (2.11)

Kulhawy and Mayne (1990), based on the work by Schmertmann in 1975 has

approximate an empirical formula to estimate the friction angle:

+

=

a

v

f

p

N

'3.202.12

tan 1

(2.12)

where pa is the atmospheric pressure in the same unit as v. More recently,

Hatanaka and Uchida (1996) suggested 2020 += corN .

2.6.2 Cohesive Soils

Based on Code of Practice for Site Investigation (BS 5930), an approximation

can be made between stiffness and undrained shear strength, cu as shown in Table

2.5.


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Table 2.5 : Variation of undrained shear strength, cu with SPT N-value (BS 5930)

SPT N-value Consistency Undrained shear

strength, cu (kN/m2)

Less than 4 Very soft Less than 20

4-10 Soft 20-40

10-30 Firm 40-75

30-50 Stiff 75-150

More than 50 Very stiff More than 150

Besides BS 5930, Stroud (1974) based on the results of undrained triaxial test

suggested that cu = KN where K is a constant in the range of 3.5 6.5 kN/m2

. Stroud

found that the average value for K is about 4.4 kN/m2. Hara et al. (1971) also

suggested that cu = 29N0.72.

2.7 Pile Driving Formulae

Many attempts have been made to determine the relationship between the

dynamic resistance of pile during driving and the static load-carrying capacity of the

pile. These intended relationships are called pile driving formulae and have been

established empirically or theoretically. According to Simon nad Menzies (2000).

Much discussion has been generated, for example, ASCE (1951), Chellis (1941),

Cummings (1940), and Greulich (1941). Conflicting opinions have been expressed.

The relationship between dynamic and static resistance of pile should be

independent of time if the formula is to have any validity (Simons and Menzies,

2000). This is clearly not the case with clays and, therefore, pile driving formulae

should not, in general, be applied to cohesive soils, but only to granular soils, that is,

sands and gravel.

Simons and Menzies (2000) suggest that the Janbu formula and the Hiley

formula are convenient to use and give reasonable predictions of the ultimate bearing


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capacity of driven piles in granular soils. Das (1986) also suggested Engineering

News Record (ENR) formula besides above mentioned formulae. His reason is that

ENR formula which was introduced during nineteenth century has gone through

several revisions over the years and is acceptable for prediction of the ultimate load.

Das also suggested a factor of safety (FOS) of 4 - 6 should be recommended to

estimate the allowable load. However, McCarthy (1998) has different opinion. He

suggested that the use of ENR formula should be discouraged because it does not

have application for existing pile driving methods.

A detailed investigation into the validity of pile driving formulae in granular

soils by Flaate (1964) suggests that there is little to choose between the Hiley andJanbu Formulae. In order to obtain a minimum factor of safety of 1.75 for any pile,

Flaate showed that it is necessary to use FOS = 2.7 with Hiley formula and FOS =

3.0 for Janbu Formula. Flaate also found out that Janbu formula gave a slightly

better correlation between tested and calculated bearing capacity and also the lowest

arithmetic mean value of the factor of safety.

2.7.1 Janbus Formula

Janbus Formula was first introduced in 1953 (Das, 1999). The ultimate

bearing capacity can be calculated based on the following formula:

Qp = SK

HW

u

R

(2.13)

where Qp is calculated ultimate bearing capacity, WR is weight of the ram, H is drop

of hammer, and S is final set (penetration / blow) while Ku is determined by the

following formulae:


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However, piles penetrates through fill may be subjected to corrosion as fills

do contain sufficient free oxygen. Tomlinson (1987) found out that steel is lost at

rate up to 0.8 mm/yr.


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3.3.1 Soil Data

The soil data consists of information on the soil boring location (station

number), soil stratigraphy and other information. From soil stratification, the

predominant soil type was qualitatively identified (cohesive or cohesionless). The

importance of this identification is addressed in the analysis section.

3.3.2 SPT Data

The standard penetration soundings information includes test location (station

number), date, soil description and lithology, water level, N value and the depth the

test halted.

3.3.3 Piling Records

Piling records consist of pile characteristics (pile identification, material type,

cross-section, total length, embedded length), and installation data (location of the

pile, date of driving, driving record, hammer type, etc.).

3.3.4 Pile Load Tests Reports

Pile load test report consist of date of loading, applied load with time, pile

head movement, pile failure under testing, and etc.


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Figure 3.3 Cumulative probability curve (Hani and Murad, 1999)

3.6.3 Mean () and Standard Deviation () of Qp/Qm

The ratio of predicted to measured ultimate pile capacity (Qp/Qm) was the

main variable considered in the analyses. This ratio (Qp/Qm) ranges from 0 to with

an optimum value of one. The methods underpredicts the measured capacity when

Qp/Qm< 1 and it overpredicts the measured capacity when Qp/Qm> 1. The mean and

standard deviation of Qp/Qm are indicators of the accuracy and precision of the

prediction method. An accurate and precise method gives mean (Qp/Qm) = 1 and

standard deviations (Qp/Qm) = 0, respectively, which means that for each pile, the

predicted pile capacity equals to the measured one. This case is ideal, however, in

reality the method is better when mean (Qp/Qm) is closer to one and standard

deviation(Qp/Qm) is closer to 0.

In order to calculate the mean () and standard deviation () of Qp/Qm, the

following equations are used (Long et al., 1999):


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CHAPTER 4

CASE STUDY

4.1 Location of Study

The site of this study is located at Mukim Jimah. Mukim Jimah is located

east of the mouth of the Sepang River and off the Kuala Lukut shoreline in the state

of Negeri Sembilan in west peninsular Malaysia. It lies at an elevation of between 0

m and 5 m below the Malaysian Land Survey Datum (MLSD, approximate Mean

Sea Level). Reference to the geological map of the site and its surroundings

(Geological Survey Malaysia, 1985) shows that the site is underlain by very soft to

soft clays, organic soils and very loose to loose sands presumably deposited during

the Pleistocene and Holocene Epochs of the Quaternary Period. The solid geology of

the site consists of meta-sedimentary rocks (Phyllite, Schist, Slate and Sandstone) of

the Devonian Period (Krishnan and Lee, 2006).

Based on description above, it is clear that the site is seated on theproblematic soils where bearing capacity and settlement problems are expected.

Besides, the site lies below mean sea level, and thus is subjected to flooding.

Therefore, fill materials are necessary to raise the level before any works can

commence.


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Figure 4.1 Site location plan (Krishnan and Lee, 2006)

Figure 4.2 Site geological cross-section (Krishnan and Lee, 2006)


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4.6 Loading Arrangement and Test Programs

As mentioned in Section 4.2, normal and quick maintained load tests were

conducted on the test piles. The tests were conducted using kentledge reaction

system (Figure 4.4). In this method, kentledge was placed onto a test frame and cribs

which rest upon the ground.

In the setup, a hydraulic jack was used to provide the load by acting against

the main beam. The hydraulic jack was operated by electric pump. Calibrated VW

Load Cell was used to indicate the applied load. The load cell was placed between

the jack and the kentledge framework and a pressure gauge linked to the hydraulicpump.

Besides manual precise level survey level, all other instruments were logged

automatic using Micro-10x Datalogger and Multilogger software, at 2 minutes

interval during loading and unloading steps. All the instruments were calibrated

before were used in the test programs.

Figure 4.4 Typical static axial compression load tests setup (Krishnan and Lee,

2006)


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57

5.3 Failure Criteria

The failure criteria are based on JKR specification as mentioned in Section

2.3. Based on the mentioned criteria, Table 5.1 summarizes the failure condition of

the test piles.

Table 5.1 : Summary of pile failure criterion

Pile No. Diameter Failure Criterion

TP3C 600 mm Total settlement exceeds 38mm (actual settlement is

40.70 mm)

TP5 500 mm Total settlement exceeds 38mm (actual settlement is41.12 mm)

TP9 400 mm Total settlement exceeds 38mm (actual settlement is

46.66 mm)

TP10 400 mm Residual settlement exceeds 12.5 mm (residual settlement

is 17.52 mm)

5.4 Predicted Versus Measured Pile Capacity

Table 5.2 summarizes the results of the analyses conducted on the

investigated piles. Among the data presented in Table 5.2 are: the pile size, type,

length, the measured ultimate load carrying capacity, and the predicted ultimate

bearing capacity. The graphs and calculations to predict ultimate bearing capacities

are given in Appendix A, B, C and D.

The predicted ultimate bearing capacity (Qp) is the sum of pile tip capacity

(Qt) and pile shaft resistance (Qs). The pile capacities Qt, Qs, and Qppredicted by the

interpretation methods, pile driving formulae, and Meyerhof method are compared

with Qm in Figures 5.1 to 5.8. Based on the graph, it is observed that prediction of

pile ultimate bearing capacities by Fuller and Hoys, and Butler and Hoys method are


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Table 5.2 : Summary of piles investigated

Pile No. TP3C TP5 TP9

Pile ID 600 mm diameter 500 mm diameter 400 mm diameter

Pile Classification Friction Friction Friction

Predominant Soil* Cohesive Cohesionless Cohesionless

Pile Length (m) 42 48 48

Types of Load Test Normal Normal Normal

Pile and Soil

Identification

Working Load (kN) 2200 1700 1150

Actual Ultimate Load (kN) Qs Qt Qu Qs Qt Qu Qs Qt

Measured Field Results 5116 1457 6573 4053 1051 5104 2692 671

Predicted Ultimate Load (kN) Qs Qt Qu Qs Qt Qu Qs Qt

Chin - - 12500 - - 8333 - -

Brinch Hansen - - 2760 - - 2532 - -Fuller and Hoy - - 6600 - - 5400 - -

Butler and Hoy - - 6400 - - 5200 - -

Load TestInterpretation

Method

De Beer - - 4300 - - 3000 - -

Janbu - - 3787 - - 2682 - -Pile Driving

Formulae ENR - - 2392 - - 1875 - -

Static

Analysis

Meyerhof 1258 2566 3824 352 376 728 607 1917

*Cohesive (mainly clayey and silty clay soils) and cohesionless (mainly sandy soils): Q s: Pile skin resistance;

ultimate capacity (Qs + Qt)


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0

1000

2000

3000

4000

5000

6000

7000

0 1000 2000 3000 4000 5000 6000 7000

Meausred Pile Capacity, Qm (kN)

PredictedPileCap

acity,Qp(kN)

Qp = 0.4721 Qm

R2 =0.90

Perfect fit

Figure 5.10 Predicted (Brinch Hansen Criterion) versus measured pile capacity

0

1000

2000

3000

4000

5000

6000

7000

0 1000 2000 3000 4000 5000 6000 7000


Pred

ictedPileCapacity,Qp(kN)

Qp = 1.0182 Qm

R2

=0.99

Perfect fit

Figure 5.11 Predicted (Fuller and Hoys Method) versus measured pile capacity

0

1000

2000

3000

4000

5000

6000

7000

0 1000 2000 3000 4000 5000 6000 7000


PredictedPileCapacity,Qp(k

N)

Qp = 0.9849 Qm

R2 =0.99

Perfect fit

Figure 5.12 Predicted (Butler and Hoys Method) versus measured pile capacity


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0

1000

2000

3000

4000

5000

6000

7000

0 1000 2000 3000 4000 5000 6000 7000


CalculatedPileCap

acity,Qp(kN)

Qp = 0.4633Qm

R2

=0.62

Perfect fit

Figure 5.16 Calculated (Meyerhofs Method) versus measured pile capacity

Inspection of Figures 5.9 to 5.16 (Qp/Qmplots) shows that Butler and Hoy

method has best fit equation Qp= 0.9849Qmwith R2 = 0.99. This method tends to

underpredict the measured pile capacity by an average of 1 percent. Therefore,

Butler and Hoy method ranks number one according to this criterion and is given R1

= 1(R1is the rank based on this criterion). The Fuller and Hoy method with Qp =

1.0182Qm(R2 = 0.99) tends to overpredict the measured capacity by 2 percents and

therefore ranks number 2 (R1 = 2). According to this criterion, Brinch Hansen, De

Beer, Janbu, ENR, and Meyerhof methods tend to underpredict the measured

ultimate pile capacity, while Chin method tends to overpredict the measured ultimate

pile capacity. The Chin method showed the inaccurate performance with Qp =

1.7793Qm(R2 = 0.98) and therefore was given R1= 8.

5.5.2 Cumulative Probability (CP)

Figures 5.17 to 5.24 show the values of P50 and P90 of each method. The

summary of the results for each method and their ranks in this criterion is shown in

Table 5.3.


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0

0.5

1

1.5

2

2.5

0 20 40 60 80 1

Cumulative probabiity (%)

Qp/Q

m

00

1.65

2.10

Figure 5.17 Cumulative probability plot for Qp/Qm (Chins Method)

00.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 20 40 60 80 1


Qp/Qm

00

0.55

0.97

Figure 5.18 Cumulative probability plot for Qp/Qm (Brinch Hansens Criterion)

0

0.2

0.4

0.6

0.8

1

1.2

0 20 40 60 80 1


Qp/Qm

00

1.00

1.12

Figure 5.19 Cumulative probability plot for Qp/Qm (Fuller and Hoys Method)


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5.5.3 Mean () and Standard Deviation () of Qp/Qm

The summary of the results for each method and their ranks in this criterion is

shown in Table 5.3. In this criterion, the arithmetic mean () and standard deviation

() of the ratio Qp/Qm values for each method were calculated. The best method is

the one that gives a mean value closerto one with a lower standard deviation, which

is the measure of scatter in the data around the mean. According to this criterion,

Fuller and Hoy method with = 0.998 and = 0.0022 ranks number one (R2 = 1)

followed by the Butler and Hoy method (R2 = 2). Brinch Hansen, De Beer, Janbu,

ENR, and Meyerhof methods have < 1, which means that these methods on

average are underpredicting the measured pile capacity. On the other hand, Chin

method has > 1, which means that these methods on average are underpredicting

the measured pile capacity.

5.5.4 Overall Performance

In order to evaluate the overall performance of the different prediction

methods, all criteria were considered in a form of an index. The Rank Index (RI) is

the algebraic sum of the ranks obtained using the three criteria. Considering Butler

and Hoy method, the RI equals to four as evaluated from RI = R1 + R2 + R3 + R4.

The Rank Index values for all other methods are presented in Table 5.3. Inspection of

Table 5.3 demonstrates that Butler and Hoy method ranks number one. This method

showed the best performance according to the evaluation criteria and therefore

considered the best methods. The Fuller and Hoy method ranks number two. The

Chin method showed the worst performance as it ranks number eight.

5.6 Discussion

The results of this study demonstrated the capability of the mentioned

methods in predicting the ultimate load carrying capacity of spun piles driven into

Mukim Jimah soils. Butler and Hoy method methods showed the best performance


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Janbu 0.51 ~ underpredicted the bearing capacity (conservative).

~showed better accuracy than ENR formula.

~not recommended for design procedure unless pile

load test is unable to be conducted.

ENR 0.36 ~ underpredicted the bearing capacity (conservative).

~not recommended for design procedure unless pile

load test is unable to be conducted.

Meyerhof 0.46 ~ underpredicted the bearing capacity (conservative).

~contradict with the field result in term of type of

pile.

~not recommended for design procedure detailed

laboratory tests are not conducted.


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CHAPTER 6

CONCLUSION AND RECOMMENDATION

5.1 General

This study presented an evaluation of the performance of eight methods in

predicting the ultimate load carrying capacity of spun piles driven into Mukim Jimah

Power Plant. Four pile load test reports, which have soil investigation report

adjacent to the test pile, were collected from Taisei Corporation. Prediction of pile

capacity was performed on four friction piles that failed during the pile load test.

5.2 Conclusion

(i) Based on the results of this study, Butler and Hoy method shows the best

capability in predicting the measured load carrying capacity of spun piles.

Fuller and Hoy method also shows competency in predicting the ultimate

load carrying capacity of piles. Other methods such as De Beer, Brinch

Hansen showed an average accuracy in predicting the ultimate carrying

capacity of spun piles. Chin method is found to be the least suitable in

predicting ultimate load carrying capacity.

(ii) It is concluded that six out of eight methods considered in the study

underpredicted bearing capacity of spun piles. These methods are Butler and

Hoy, Brinch Hansen, De Beer, Meyerhof, Janbu, and ENR method. Except


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REFERENCES

Airhart, T.P. and et. al. (1969). Pile-Soil System Response in a Cohesive Soil.

Performance of Deep Foundations. Philadelphia: ASTM. 264-294.

Bachand, M.L.Jr. (1999). Express Method of Pile Testing by Static Cyclic Loading.

University of Massachusetts Lowell: Master Thesis.

Bowles, J.E. (1996). Foundation Analysis and Design. 5th edition. New York:

McGraw-Hill Companies Inc. 167-181.

Bozozuk, M. (1981). Bearing Capacity of Pile Preloaded by Downdrag.

Proceedings of Tenth International Conference on Soil Mechanics and

Foundation Engineering. Stockholm. Vol. 2. 631-636.

Briaud, J.L. et. al. (1989). Analysis of Pile Load Test at Lock and Dam 26.

Proceedings of Foundation Engineering: Current Principles and Practices.

American Society of Civil Engineers. Vol. 2. 925-942

British Standard Institution (1987). British Standard 5930: Code of Practice for Site

Investigation. London.

Broms, B.B. (1965). Methods of calculating the Ultimate Bearing capacity of Piles:

A Summary. Journal of the Geotechnical Engineering Division. American

Society of Civil Engineers. Vol. 91, No. GT3. 187-222.

Butler, H.D., and H.E. Hoy (1977). The Texas Quick-Load Method for Foundation

Load Testing-User's Manual. Report No. FHWA-IP-77-8.

Coduto, D.P. (2001). Foundation Design: Principles and Prctices. 2nd edition. New

Jersey: Prentice Hall. 24-35.


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99/133


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Leonards, G.A. (1982). Investigation of Failures. Journal of Geotechnical

Engineering. American Society of Civil Engineers. Vol. 117, No. 1. 172-188.

Liao, S.S.C., and Whitman, R.V. (1986). Overburden Correction Factors for SPT in

Sand. Journal of Geotechnical Engineering. American Society of Civil

Engineers. Vol. 114, No. 3. 373-377.

Long, J. H., and Wysockey, M. H. (1999). Accuracy of Methods for Predicting

Axial Capacity of Deep Foundations. Proceedings of OTRC 99 Conference:

Analysis, Design, Construction, and Testing of Deep Foundation. Reston:

ASCE, 190195.

McCarthy, D.F. (1998). Essentials of Soil Mechanics and Foundations. 5th edition.

New York: Prentice Hall Inc. 147-149, 497-503

Meyerhof, G.G. (1959). Compaction of Sands and Bearing Capacity of Piles.Journal

of the Geotechnical Engineering Division. American Society of Civil

Engineers. Vol. 85. 1-29.

Meyerhof, G.G. (1976). Bearing Capacity and Settlement of Pile Foundations.

Journal of the Geotechnical Engineering Division. American Society of Civil

Engineers. Vol. 102. 197-228.

Nor Azizi Yussoff (2003). Foundation Engineering: Lecture Notes. Batu Pahat:

Kolej Universiti Teknologi Tun Hussein Onn. (Unpublished).

Peck, R.B., Hanson, W.E., and Thornburn, T.H. (1974). Foundation Engineering.

New York: John Wiley and Sons, Inc. 514.

Poulos, H.G. and Davis, E.H. (1980). Pile Foundation Analysis and Design. New

York: John Wiley and Sons, Inc.

Ramli Nazir (2005). Advanced Foundation Engineering: Lecture Notes. JohoreBahru: Universiti Teknologi Malaysia. (Unpublished)


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83

Vijayvergiya, V.N., and Focht, J.A., Jr. (1972). A New Way to Predict Capacity of

Piles in Clay. Proceedings of Conference of Offshore Technology. Houston:

Forth Offshore Technology. Conference Paper 1718.

Whitaker, T., (1976). The Design of Piled Foundations. 2nd edition. Oxford:

Pergamon Press. 135-150.

Wolff, T.F. (1989). Pile Capacity Prediction Using Parameter Functions.

Geotechnical Special Publication. American Society of Civil Engineers. No.

23. 96-106.


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Appendix A1

Summary of Average Pile Top Settlement for Test Pile TP3C


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Appendix A2

Bearing Capacity of Test Pile TP3C from Load Test Interpretation Method

Chin's Method

y = 0.00008x + 0.00367

0

0.001

0.002

0.003

0.004

0.005

0.006

0.007

0.008

0 5 10 15 20 25 30 35 40 45

Settlement (mm)

Settlement/Load(mm/kN)

Ultimate Load (Qu) = 1/0.00008 = 12500 kN

Brinch Hansen's 80% Criterion

y = -0.00002x + 0.00169

0

0.001

0.002

0.003

0 10 20 30 40 5

Settlement (mm)

Settlement^0.5/Load(mm^0.5/kN)

0

Ultimate Load (Qu) = 0.5/(0.00002x0.00169) = 2720 kN


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Fuller and Hoy's Method

0

1000

2000

3000

4000

5000

6000

7000

0 10 20 30 40

Settlement (mm)

Load(kN)

50

Qp

From the graph, it is estimated the ultimate bearing capacity is 6600 kN .

Butler and Hoy's Method

0

1000

2000

3000

4000

5000

6000

7000

0 10 20 30 40 5

Settlement (mm)

Load(kN)

0

Qp

From the graph, it is estimated the ultimate bearing capacity is 6400 kN .


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87

De Beer's Method

100

1000

10000

1 10 100

Settlement (mm)

Load(kN)

Qp

From the graph, it is estimated the ultimate bearing capacity is 4300 kN.


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Appendix A3

Bearing Capacity of Test Pile TP3C from Pile Driving Formulae

Weight of ram, WR = 107.91 kN

Weight of Pile, Wp = 165.47 kN

Area of pile, Ap = 0.16708 m2

Young modulus of pile, Ep = 43.25 x 106 kN/m2

Drop of hammer, H = 1.2 m

Penetration of pile per, S = 0.0012 m

hammer blow

Efficiency, (Janbu) = 0.70 (good driving condition)Efficiency, (ENR) = 0.9 (assuming the efficiency is maximum)

Restitution factor, n = 0.5 (assuming the restitution is maximum)

Constant, C = 0.0254 m

Janbu Formula

Janbu formula, Qp =

SK

HW

u

R

= 3787 kN

where Ku =

++

5.0

11d

ed C

C

= 19.9

Cd =R

p

W

W15.075.0 + = 0.98

e = 2SEA

HLWpp

R = 366

Engineer News Record (ENR) Formula

ENR formula, Qp =pR

PRR

WW

WnWx

CS

HW

+

+

+

2

= 2392 kN


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89

Appendix A4

Bearing Capacity of Test Pile TP3C from Static Analysis (Meyerhof Method)

0 9.0 m

Loose sand, average unit weight, avg = 16.5 kN/m2

Navg = 3

9.0 m 25.8 m

Soft clay, average unit weight, avg = 17.5 kN/m

2

Navg = 4

Cu = 20 kN/m2

25.8 m 38.7 m

Medium dense sand, average unit weight, avg = 18.75 kN/m2

Navg = 17

38.7 m 42.0 m

Very dense sand, average unit weight, avg = 18.75 kN/m2

Navg = 176

For Loose SandBased on result from TP9, Navg is 3.

Effective overburden stress, v = (16.5 9.81) x 9

= 60.2 kN/m2


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90

Based on Peck, Hanson and Thornburn (1974)

Ncor =v

fN'0105.0

20log77.0

= 3.5

Based on Meyerhof (1976)

Skin resistance, qs1 = 2NcorpL

= 2 x 3.5 x 0.6 x 9

= 119 kN

For Soft ClaySkin resistance, qs = cupL

From Figure 2.15, = 1.0

Thus, qs2 = 1.0 x 20 x 0.6 x 16.8

= 633 kN

For Medium Dense Sand

Effective overburden stress, v = (16.5 9.81) x 9.0 + (17.5 9.81) x 16.8

+ (18.75 9.81) x 12.9

= 304.7 kN/m2


Ncor =v

fN'0105.0

20log77.0

= 10.4



= 2 x 10.4 x 0.6 x 6.8

= 506 kN

Total skin resistance, Qs = qs1 + qs2 + qs3 = 1258 kN


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For Hard Layer

Effective overburden stress, v = 304.7 + ( 20.5 9.81) x 3.3

= 340 kN/m2


Ncor =v

fN'0105.0

20log77.0

= 89

Based on Wolff (1989)

200054.03.01.27 corcor NN +=

= 52 > 45. Assume friction angle is 45.

The depth of penetration in bearing stratum, Lb is 0.2.

Thus, Lb / D = 0.3 and is less than (Lb / D)critical. The value for (Lb / D)critical is around

24 (from Figure 2.8). Take (Lb / D).

From Figure 2.8, bearing capacity factor, Nq is around 240.

Ultimate point load, Qtu = Apv Nq

= 0.16708 x 340 x 240

= 13634 kN

However, limiting point load, Qtl = Ap50Nqtan

= 0.16708 x 50 x 240 x tan 52

= 2566 kN

Since Qtl < Qtu, the point bearing capacity, Qt is 2566 kN.

Thus, the bearing capacity of pile, Qp= Qt + Qs

= 2566 + 1258

= 3824 kN


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Appendix B1

Summary of Average Pile Top Settlement for Test Pile TP5


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93

Appendix B2

Bearing Capacity of Test Pile TP5 from Load Test Interpretation Method

Chin's Method

y = 0.00012x + 0.00385

0

0.001

0.002

0.003

0.004

0.005

0.006

0.007

0.008

0.009

0.01

0 10 20 30 40

Settlement (mm)

Settlement/Load(mm/kN

50

)



y = -0.00002x + 0.00195

0

0.001

0.002

0.003

0.004

0 10 20 30 40

Settlement (mm)

S

ettlement^0.5/Load(mm^0.5/kN

50

)



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96

Appendix B3

Bearing Capacity of Test Pile TP5 from Pile Driving Formulae







hammer blow




Janbu Formula

Janbu formula, Qp =

SK

HW

u

R

= 2682 kN

where Ku =

++

5.0

11d

ed C

C

= 105.6

Cd =R

p

W

W15.075.0 + = 0.97

e = 2SEA

HLWpp

R = 11299


ENR formula, Qp =pR

PRR

WW

WnWx

CS

HW

+

+

+

2

= 1875 kN


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Appendix B4

Bearing Capacity of Test Pile TP5 from Static Analysis (Meyerhof Method)

0 10.5 m


Navg = 3

10.5 m 26.0 m

Soft clay, average unit weight, avg = 17.5 kN/m2

Navg = 2

Cu = 10 kN/m2

26.0 m 43.0 m

Dense sand, average unit weight, avg = 18.75 kN/m2

Navg = 32

For Loose Sand

Based on result from TP9, Navg is 3.

Effective overburden stress, v = (16.5 9.81) x 10.5

= 70.2 kN/m2


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98


Ncor =v

fN'0105.0

20log77.0

= 3.3



= 2 x 3.3 x 0.5 x 10.5

= 109 kN

For Soft ClaySkin resistance, qs = cupL


Thus, qs2 = 1.0 x 10 x 0.5 x 15.5

= 243 kN

Total skin resistance, Qs = qs1 + qs2 = 352 kN



+ (18.75 9.81) x 17.0

= 341 kN/m2


Ncor =v

fN'0105.0

20log77.0

= 18.4


200054.03.01.27 corcor NN +=

= 33


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Thus, Lb / D = 24.2 and is less than (Lb / D)critical. The value for (Lb / D)critical is

around 7 (from Figure 2.8). Take (Lb / D)critical.



= 0.115925 x 341 x 100

= 3953 kN


= 0.115925 x 50 x 100 x tan 33

= 376 kN



= 376 + 352

= 728 kN


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Appendix C1



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101

Appendix C2

Bearing Capacity of Test Pile TP9 from Load Test Interpretation Method

Chin's M ethod

y = 0.00017x + 0.00630

0

0.01

0.02

0 5 10 15 20 25 30 35 40 45 50

Settlement (mm)

S

ettlement/Load(mm/kN



y = -0.00002x + 0.00297

0

0.001

0.002

0.003

0.004

0.005

0.006

0 10 20 30 40 5

Settlement (mm)

Se

ttlement^0.5/Load(mm^0.5/k

0

N



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0

500

1000

1500

2000

2500

3000

3500

4000

0 10 20 30 40

Settlement (mm)

Load(kN)

50

Qp



0

500

1000

1500

2000

2500

3000

3500

4000

0 10 20 30 40 5

Settlement (mm)

Load(kN)

0

Qp



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De Beer's Method

100

1000

10000

1 10

Settlement (mm)

Load(kN

100

)

Qp



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Appendix C3








hammer blow




Janbu Formula

Janbu formula, Qp =

SK

HW

u

R

= 1545 kN

where Ku =

++

5.0

11d

ed C

C

= 12

Cd =R

p

W

W15.075.0 + = 0.9

e = 2SEA

HLWpp

R = 128


ENR formula, Qp =pR

PRR

WW

WnWx

CS

HW

+

+

+

2

= 1078 kN


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Appendix C4


0 6.8 m


Navg = 3

6.8 m 19.0 m


Navg = 2

cu = 10 kN/m2

19.0 m 39.0 m


Navg = 13

39.0 m 45.0 m


Navg = 165

For Loose Sand


= 45.5 kN/m2


Ncor =v

fN'0105.0

20log77.0

= 3.7


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= 2 x 3.7 x 0.4 x 6.8

= 63 kN

For Soft Clay

Skin resistance, qs = cupL


Thus, qs2 = 1.0 x 10 x 0.4 x 12.2



+ (18.75 9.81) x 20

= 318.1 kN/m2


Ncor =v

fN'0105.0

20log77.0

= 7.8



= 2 x 7.8 x 0.4 x 6.8

= 391 kN

Total skin resistance, Qs = qs1 + qs2 + qs3 = 607 kN

For Hard Layer

Effective overburden stress, v = 318.1 + ( 20.5 9.81) x 6

= 382.2 kN/m2


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Ncor =v

fN'0105.0

20log77.0

= 89


200054.03.01.27 corcor NN += = 50 > 45. Assume friction angle is 45.


Thus, Lb / D = 6.8 and is less than (Lb / D)critical. The value for (Lb / D)critical is around

24 (from Figure 2.8). Take (Lb / D).



= 0.080425 x 382.2 x 400

= 12295 kN


= 0.080425 x 50 x 400 x tan 50

= 1917 kN



= 1917 + 607

= 2524 kN


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Appendix D1



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110


0

50

100

150

200

250

300

350

400

450

500

0 5 10 15 20 25

Settlement (mm)

Load(kN)

QP



0

50

100

150

200

250

300

350

400

450

500

0 5 10 15 20 25

Settlement (mm)

Load

(kN)

QP



130/133

111

De Beer's Method

10

100

1000

1 10 100

Settlement (mm)

Load(kN)

QP



131/133

112

Appendix D3








hammer blow




Janbu Formula

Janbu formula, Qp =

SK

HW

u

R

= 350 kN

where Ku =

++

5.0

11d

ed C

C

= 1.7

Cd =R

p

W

W15.075.0 + = 0.8

e = 2SEA

HLWpp

R = 0.15


ENR formula, Qp =pR

PRR

WW

WnWx

CS

HW

+

+

+

2

= 272 kN


132/133

113

Appendix D4


0 7.8 m


Navg = 3

7.8 m 19.0 m


Navg = 3

cu = 15 kN/m2

19.0 m 41.2 m


Navg = 26

41.2 m 46.0 m


Navg = 178

For Loose Sand


= 52.2 kN/m2


Ncor =v

fN'0105.0

20log77.0

= 3.6


133/133

114



= 2 x 3.6 x 0.4 x 7.8

= 71 kN

For Soft Clay

Skin resistance, qs = cupL


Thus, qs2 = 1.0 x 15 x 0.4 x 11.2

= 101 kN

Total skin resistance, Qs = qs1 + qs2 = 172 kN

This pile is carry by skin resistance alone as the soft clay is not capable of generating

end bearing for the pile. Thus, Qp = Qs.

wong char ng chen mad 2006 ttt

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