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PSZ 19: 16 (Pind. 1/97)
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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i
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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ii
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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iii
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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vii
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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ix
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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xii
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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4
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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5
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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6
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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9
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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12
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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44
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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50
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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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
Meausred Pile Capacity, Qm (kN)
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
Meausred Pile Capacity, Qm (kN)
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
Meausred Pile Capacity, Qm (kN)
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
Cumulative probabiity (%)
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
Cumulative probabiity (%)
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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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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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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85
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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86
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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88
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
Based on Peck, Hanson and Thornburn (1974)
Ncor =v
fN'0105.0
20log77.0
= 10.4
Based on Meyerhof (1976)
Skin resistance, qs3 = 2NcorpL
= 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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91
For Hard Layer
Effective overburden stress, v = 304.7 + ( 20.5 9.81) x 3.3
= 340 kN/m2
Based on Peck, Hanson and Thornburn (1974)
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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92
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
)
Ultimate Load (Qu) = 1/0.00012 = 8333 kN
Brinch Hansen's 80% Criterion
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
)
Ultimate Load (Qu) = 0.5/(0.00002x0.00195) = 2532 kN
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Appendix B3
Bearing Capacity of Test Pile TP5 from Pile Driving Formulae
Weight of ram, WR = 88.29 kN
Weight of Pile, Wp = 131.21 kN
Area of pile, Ap = 0.115925 m2
Young modulus of pile, Ep = 43.25 x 106 kN/m2
Drop of hammer, H = 1.1 m
Penetration of pile per, S = 0.00024 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
= 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
Engineer News Record (ENR) Formula
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
Loose sand, average unit weight, avg = 16.5 kN/m2
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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Based on Peck, Hanson and Thornburn (1974)
Ncor =v
fN'0105.0
20log77.0
= 3.3
Based on Meyerhof (1976)
Skin resistance, qs1 = 2NcorpL
= 2 x 3.3 x 0.5 x 10.5
= 109 kN
For Soft ClaySkin resistance, qs = cupL
From Figure 2.15, = 1.0
Thus, qs2 = 1.0 x 10 x 0.5 x 15.5
= 243 kN
Total skin resistance, Qs = qs1 + qs2 = 352 kN
For Medium Dense Sand
Effective overburden stress, v = (16.5 9.81) x 10.5 + (17.5 9.81) x 15.5
+ (18.75 9.81) x 17.0
= 341 kN/m2
Based on Peck, Hanson and Thornburn (1974)
Ncor =v
fN'0105.0
20log77.0
= 18.4
Based on Wolff (1989)
200054.03.01.27 corcor NN +=
= 33
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The depth of penetration in bearing stratum, Lb is 12.1.
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.
From Figure 2.8, bearing capacity factor, Nq is around 100.
Ultimate point load, Qtu = Apv Nq
= 0.115925 x 341 x 100
= 3953 kN
However, limiting point load, Qtl = Ap50Nqtan
= 0.115925 x 50 x 100 x tan 33
= 376 kN
Since Qtl < Qtu, the point bearing capacity, Qt is 187 kN.
Thus, the bearing capacity of pile, Qp= Qt + Qs
= 376 + 352
= 728 kN
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100
Appendix C1
Summary of Average Pile Top Settlement for Test Pile TP9
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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
Ultimate Load (Qu) = 1/0.00017 = 5882 kN
Brinch Hansen's 80% Criterion
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
Ultimate Load (Qu) = 0.5/(0.00002x0.00297) = 2051 kN
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Fuller and Hoy's Method
0
500
1000
1500
2000
2500
3000
3500
4000
0 10 20 30 40
Settlement (mm)
Load(kN)
50
Qp
From the graph, it is estimated the ultimate bearing capacity is 3300 kN.
Butler and Hoy's Method
0
500
1000
1500
2000
2500
3000
3500
4000
0 10 20 30 40 5
Settlement (mm)
Load(kN)
0
Qp
From the graph, it is estimated the ultimate bearing capacity is 3200 kN.
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De Beer's Method
100
1000
10000
1 10
Settlement (mm)
Load(kN
100
)
Qp
From the graph, it is estimated the ultimate bearing capacity is 2100 kN.
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104
Appendix C3
Bearing Capacity of Test Pile TP9 from Pile Driving Formulae
Weight of ram, WR = 88.29 kN
Weight of Pile, Wp = 91.03 kN
Area of pile, Ap = 0.080425 m2
Young modulus of pile, Ep = 43.25 x 106 kN/m2
Drop of hammer, H = 0.6 m
Penetration of pile per, S = 0.002 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
= 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
Engineer News Record (ENR) Formula
ENR formula, Qp =pR
PRR
WW
WnWx
CS
HW
+
+
+
2
= 1078 kN
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Appendix C4
Bearing Capacity of Test Pile TP9 from Static Analysis (Meyerhof Method)
0 6.8 m
Loose sand, average unit weight, avg = 16.5 kN/m3
Navg = 3
6.8 m 19.0 m
Soft clay, average unit weight, avg = 17.5 kN/m3
Navg = 2
cu = 10 kN/m2
19.0 m 39.0 m
Medium dense sand, average unit weight, avg = 18.75 kN/m3
Navg = 13
39.0 m 45.0 m
Very dense sand, average unit weight, avg = 20.5 kN/m3
Navg = 165
For Loose Sand
Effective overburden stress, v = (16.5 9.81) x 6.8
= 45.5 kN/m2
Based on Peck, Hanson and Thornburn (1974)
Ncor =v
fN'0105.0
20log77.0
= 3.7
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Based on Meyerhof (1976)
Skin resistance, qs1 = 2NcorpL
= 2 x 3.7 x 0.4 x 6.8
= 63 kN
For Soft Clay
Skin resistance, qs = cupL
From Figure 2.15, = 1.0
Thus, qs2 = 1.0 x 10 x 0.4 x 12.2
For Medium Dense Sand
Effective overburden stress, v = (16.5 9.81) x 6.8 + (17.5 9.81) x 12.2
+ (18.75 9.81) x 20
= 318.1 kN/m2
Based on Peck, Hanson and Thornburn (1974)
Ncor =v
fN'0105.0
20log77.0
= 7.8
Based on Meyerhof (1976)
Skin resistance, qs3 = 2NcorpL
= 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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Based on Peck, Hanson and Thornburn (1974)
Ncor =v
fN'0105.0
20log77.0
= 89
Based on Wolff (1989)
200054.03.01.27 corcor NN += = 50 > 45. Assume friction angle is 45.
The depth of penetration in bearing stratum, Lb is 2.8.
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).
From Figure 2.8, bearing capacity factor, Nq is around 400.
Ultimate point load, Qtu = Apv Nq
= 0.080425 x 382.2 x 400
= 12295 kN
However, limiting point load, Qtl = Ap50Nqtan
= 0.080425 x 50 x 400 x tan 50
= 1917 kN
Since Qtl < Qtu, the point bearing capacity, Qt is 1917 kN.
Thus, the bearing capacity of pile, Qp= Qt + Qs
= 1917 + 607
= 2524 kN
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Appendix D1
Summary of Average Pile Top Settlement for Test Pile TP10
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Fuller and Hoy's Method
0
50
100
150
200
250
300
350
400
450
500
0 5 10 15 20 25
Settlement (mm)
Load(kN)
QP
From the graph, it is estimated the ultimate bearing capacity is 420 kN.
Butler and Hoy's Method
0
50
100
150
200
250
300
350
400
450
500
0 5 10 15 20 25
Settlement (mm)
Load
(kN)
QP
From the graph, it is estimated the ultimate bearing capacity is 390 kN.
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De Beer's Method
10
100
1000
1 10 100
Settlement (mm)
Load(kN)
QP
From the graph, it is estimated the ultimate bearing capacity is 230 kN.
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Appendix D3
Bearing Capacity of Test Pile TP10 from Pile Driving Formulae
Weight of ram, WR = 88.29 kN
Weight of Pile, Wp = 34.14 kN
Area of pile, Ap = 0.080425 m2
Young modulus of pile, Ep = 43.25 x 106 kN/m2
Drop of hammer, H = 0.2 m
Penetration of pile per, S = 0.0208 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
= 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
Engineer News Record (ENR) Formula
ENR formula, Qp =pR
PRR
WW
WnWx
CS
HW
+
+
+
2
= 272 kN
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Appendix D4
Bearing Capacity of Test Pile TP10 from Static Analysis (Meyerhof Method)
0 7.8 m
Loose sand, average unit weight, avg = 16.5 kN/m2
Navg = 3
7.8 m 19.0 m
Soft clay, average unit weight, avg = 17.5 kN/m2
Navg = 3
cu = 15 kN/m2
19.0 m 41.2 m
Medium dense sand, average unit weight, avg = 18.75 kN/m2
Navg = 26
41.2 m 46.0 m
Very dense sand, average unit weight, avg = 18.75 kN/m2
Navg = 178
For Loose Sand
Effective overburden stress, v = (16.5 9.81) x 7.8
= 52.2 kN/m2
Based on Peck, Hanson and Thornburn (1974)
Ncor =v
fN'0105.0
20log77.0
= 3.6
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Based on Meyerhof (1976)
Skin resistance, qs1 = 2NcorpL
= 2 x 3.6 x 0.4 x 7.8
= 71 kN
For Soft Clay
Skin resistance, qs = cupL
From Figure 2.15, = 1.0
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.