COMPARISON BETWEEN METHODS OF ANALYSIS FOR DEFLECTION OF LATERALLY LOADED PILES
LOW SIAW MEI
UNIVERSITI TEKNOLOGI MALAYSIA
iii
Especially to my Father, Low Kheng Kin, Mother, Yong Hee Hung, Grandfather, Kapitan Lau Nguong Tieng And My beloved late grandmother, Ling Ai Ting. You guide me to success.
iv
ACKNOWLEDGEMENT
Special thank to my supervisor, Professor Dr. Khairul Anuar Kassim for his guidance, assistance and encouragement in all aspects of this Master Project. His positive comments and remedies during the course of preparing this project are gratefully acknowledged. His continuous patience and availability to attend to any doubts whenever needed deserves my heartiest gratitude.
I wish to express my sincere appreciation to my colleagues for their encouragement, guidance, and assistance.
Without their continued support and
interest, this project report would not have been the same as presented here.
I would also like to take this opportunity to thank my fellow postgraduate course mates in the Faculty of Civil Engineering for their continuous support, discussions and friendly interactions during the course of my study. Their friendship always keeps me going to achieve my dreams. My heartiest appreciation also goes to all academic and non-academic members of the Faculty of Civil Engineering, for their continuous cooperation during the duration of my study in Universiti Teknologi Malaysia.
Great appreciation is expressed to my father, Low Kheng Kin and my mother, Yong Hee Hung.
Without their understanding, support and encouragement in
assisting me to pursue my Masters Degree, I may not have come thus far.
v
ABSTRACT
Deep foundation, which used extensively to support highway structures, machinery foundation, high rise building, etc are often subjected to both axial and lateral loads. To obtain a safe and economical design, the method adopted for design of lateral deflection must be appropriate. In this thesis, two different methods of analysis for the ground-line deflection of the single, elastic, free-head piles have been compared with the available test results obtained from full-scale instrumented test piles. The basis for comparison is on the variation in pile installation methods and types of soil in Malaysia. Two design methods were selected; one is the rational method of Broms and the other is a more rigorous method of Characteristic Load Method (CLM). From the results obtained, it is found that Broms’ method gives more conservative value (around 59% to 70% larger than measured value) of lateral deflection compared to CLM. Lateral deflections calculated using CLM were found to be in good agreement (around 2% to 24% larger than measured value) with values measured in field load tests.
vi
ABSTRAK
Asas dalam yang mana digunakan dengan banyak untuk menanggung struktur lebuhraya, asas bagi tapak mesin-mesin, bangunan cakar langit, dan lain-lain selalu tertakluk kepada beban terus dan sisi untuk mendapatkan satu rekabentuk yang selamat dan ekonomik, kaedah rekabentuk pesongan sisi yang digunapakai mesti berpatutan. Dalam tesis ini, dua kaedah mudah digunakan untuk menganalisa dan membandingkan pesongan pada permukaan tanah bagi cerucuk individu, cerucuk elastic dan cerucuk free-head yang diperolehi daripada keputusan ujian yang dijalankan ke atas cerucuk yang diistrumentasikan. Asas bagi perbandingan ini adalah berdasarkan kepada perbezaan dalam kaedah pemasangan dan jenis tanah di Malaysia. Dua kaedah rekabentuk dipilih; Kaedah Broms yang rasional dan Kaedah Beban Karateristik (CLM). Kaedah Broms memberikan nilai pesongan sisi yang lebih konservatif (lebih kurang 59% hingga 70% lebih besar dari nilai yang diukur) berbanding dengan CLM. Pengiraan pesongan sisi menggunakan kaedah CLM pula menunjukkan nilai yang hampir (lebih kurang 2% hingga 24% lebih besar dari nilai yang diukur) dengan nilai yang dihitung daripada ujian beban tapak.
vii
TABLE OF CONTENTS
CHAPTER
TITLE
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENT
iv
ABSTRACT
v
ABSTRAK
vi
TABLE OF CONTENTS
vii
LIST OF TABLES
xii
LIST OF FIGURES
xiv
LIST OF SYMBOLS
xvi
LIST OF APPENDICES
1
2
PAGE
xviii
INTRODUCTION 1.1 Background of Thesis
1
1.2 Nature of the Problem
2
1.3 Influence of Analytical Method on Engineering Practice
3
1.4 Aim and Objective of the Thesis
4
1.5 Scope
4
1.6 Important of Thesis
6
LITERATURE REVIEW 2.1 Background
7
2.2 Broms’ Method
8
2.2.1
Introduction
9
viii CHAPTER
TITLE
PAGE
2.2.2
Concepts Employed in Broms’ Method
2.2.3
Broms’ Deflection Equations
10
2.2.3.1 Piles in Cohesionless Soil
10
2.2.3.2 Piles in Cohesive Soil
10
2.3 Characteristic Load Method
9
11
2.3.1
Introduction
11
2.3.2
Concepts of Characteristic Load Method
12
2.3.3 Characteristic Load Method Equations 2.3.3.1
13
Dimensionless Relationship with Characteristic Load Pc and Moment Mc
13
2.3.3.2 Deflection due to Combined Load and Moment
3
4
15
INSTRUMENTED FIELD LOAD TEST 3.1 Introduction
17
3.2 Selection of Test Pile
18
3.3 Installation of Test Pile
18
3.4 Testing Procedures
19
3.5 Interpretation of Data
21
METHODOLOGY 4.1 Introduction
22
4.2 Data Collection
23
4.3 Data Analysis
24
4.3.1
Calculating Ground-Line Deflection using Method of Broms
4.3.2
24
Calculating Ground-Line Deflection using Characteristic Load Method
25
4.4 Data Presentation
25
4.5 Data Interpretation and Results
26
ix CHAPTER
5
TITLE
PAGE
DATA COLLECTION 5.1 Introduction
27
5.2 Site 1 – 1400MW Coal Fired Power Plant Project in Jimah, Negeri Sembilan
28
5.2.1
Introduction
28
5.2.2
Geological Background of the Site
29
5.2.3
Appreciation of Subsoil Condition after
30
Reclamation 5.2.4
Scope
30
5.2.5
Location of the Test Piles and Subsurface Information
5.2.6 Test Piles Installation 5.2.6.1
5.2.6.2
31 32
1050mm Diameter Cast In-situ Bored Piles Installation
32
600mm Diameter Spun Bored
33
Installation 5.2.7
Proposed Instrumentation
33
5.2.8 Pile Movement Monitoring System
34
5.2.9
34
Static Maintained Load Test
5.2.10 Test Results
35
5.2.10.1 Test Results for 1050mm Diameter Cast In-situ Bored Piles
35
5.2.10.2 Test Results for 600mm Diameter Spun Piles
39
5.3 Site 2 – 2100MW Coal Fired Power Plant Project in Tanjung Bin, Johor
43
5.3.1
Introduction
43
5.3.2
Geological Background of the Site
43
5.3.3
Appreciation of Subsoil Condition after
44
Reclamation 5.3.4
Scope
45
x CHAPTER
TITLE
5.3.5
PAGE
Location of the Test Piles and Subsurface Information
45
5.3.6 Test Piles Installation
45
5.3.7
46
Proposed Instrumentation
5.3.8 Pile Movement Monitoring System
46
5.3.9
47
Static Maintained Load Test
5.3.10 Test Results
48
5.4 Site 3 – A-380 Hangar/Workshop Facility at MAS Complex in KLIA, Sepang, Selangor
51
5.4.1
Introduction
51
5.4.2
Geological Background of the Site
51
5.4.3
Scope
52
5.4.4
Location of the Test Piles and Subsurface Information
5.4.5 Test Piles Installation
53
5.4.6
54
Proposed Instrumentation
5.4.7 Pile Movement Monitoring System
54
5.4.8
55
Static Maintained Load Test
5.4.9 Test Results
6
7
53
56
DATA ANALYSIS 6.1 Introduction
61
6.2 Ground-Line Deflection Formulations
62
6.2.1
Broms’ Ground-Line Deflection Formulation
63
6.2.2
CLM’s Ground-Line Deflection Formulation
66
RESULTS AND DISCUSSIONS 7.1 Introduction
73
7.2 Results of Analyses for Ground-Line Deflection
73
xi CHAPTER
TITLE
PAGE
7.3 Comparison with Pile Installation Methods in Cohesionless Soil
76
7.4 Comparison with Types of Soil for Cast In-situ Bored Piles
78
7.5 Investigation of the Case for Spun Piles Installed in Cohesionless Soil
8
80
7.6 Discussion
83
7.7 Summary of Results and Discussion
83
CONCLUSIONS AND RECOMMENDATIONS 8.1 Conclusions
85
8.2 Recommendations
86
REFERENCES
87
APPENDICES
89-129
xii
LIST OF TABLES
TABLE NO.
TITLE
PAGE
2.1
Values of coefficient n1 (after Broms, 1964a)
11
2.2
Values of coefficient n2 (after Broms, 1964a)
11
2.3
Minimum Pile Lengths for Characteristic Load Method
12
2.4
Typical ε50 values (Matlock, 1970)
14
2.5
Values of the exponents m and n (Evans and Duncan, 1982)
2.6
Constants for Load-deflection equations yt / D = a1(Pt / Pc)b1 (Brettmann & Duncan, 1996)
2.7
14
15
Constants for Moment-deflection equations yt / D = a2(Mt / Mc)b2 (Brettmann & Duncan, 1996)
15
5.1
Summary of Site Data
28
5.2
Summary of Subsoil Information for Site 1
31
5.3
Summary of Pile Information for 1050mm Diameter Cast In-situ Bored Piles at Site 1
5.4
Summary of Pile Information for 600mm Diameter Spun Piles at Site 1
5.5
33
Summary of the Lateral Deflection for 1050mm Diameter Cast In-situ Bored Piles at Site 1
5.6
32
36
Summary of the Lateral Deflection for 600mm Diameter Spun Piles at Site 1
40
5.7
Summary of Subsoil Information for Site 2
45
5.8
Summary of Pile Information for 600mm Diameter Spun Piles at Site 2
46
xiii TABLE NO.
5.9
TITLE
PAGE
Summary of the Lateral Deflection for 600mm Diameter Spun Piles at Site 2
49
5.10
Summary of Subsoil Information for Site 3
53
5.11
Summary of Pile Information for 1050mm Diameter Cast In-situ Bored Piles at Site 3
5.12
Summary of the Lateral Deflection for 1050mm Diameter Cast In-situ Bored Piles at Site 3
7.1
75
Summary of the Lateral Deflection for 1050mm Diameter Cast In-situ Piles in Cohesive Soil
7.4
74
Summary of the Lateral Deflection for 1050mm Diameter Cast In-situ Piles in Cohesionless Soil
7.3
57
Summary of the Lateral Deflection for 600mm Diameter Spun Piles in Cohesionless Soil
7.2
54
76
Summary of the Lateral Deflection for 600mm Diameter Spun Piles in Cohesionless Soil at Site 1, Jimah, Negeri Sembilan
7.5
80
Summary of the Lateral Deflection for 600mm Diameter Spun Piles in Cohesionless Soil at Site 2, Tanjung Bin, Johor
80
xiv
LIST OF FIGURES
FIGURE NO.
TITLE
PAGE
1.1
Location of Test Piles Site
5
2.1
Long Vertical Free-head Pile under Horizontal Load
7
3.1
Typical Set-up for Simultaneous Testing of Two Piles under Lateral Loading
20
3.2
Device for Measuring Pile-Head Displacement
21
4.1
Sequence Used to Carry Out the Comparison of the Calculated and Measured Lateral Deflection of the Test Piles
23
5.1
Typical Subsoil Profile (Borehole ref. ABH-27)
29
5.2
Plot of Lateral Deflection for TP1 at Site 1 from LVDTs and Inclinometer Measurements
5.3
Plot of Lateral Deflection for TP2 at Site 1 from LVDTs and Inclinometer Measurements
5.4
38
Plot of Lateral Deflection for TP3c at Site 1 from LVDTs and Inclinometer Measurements
5.5
38
42
Plot of Lateral Deflection for TP4 at Site 1 from LVDTs and Inclinometer Measurements
42
5.6
Typical Subsoil Profile (Borehole ref. BBH-12)
44
5.7
Plot of Lateral Deflection for TP2a at Site 2 from LDT and Inclinometer Measurements
5.8
5.9
50
Plot of Lateral Deflection for TP2b at Site 2 from LDT Measurements
50
Typical Subsoil Profile (Borehole ref. BH-6)
52
xv FIGURE NO.
5.10
TITLE
Plot of Lateral Deflection for TP1 at Site 3 from LSDTs and Inclinometer Measurements
5.11
77
Comparison of Measured and Calculated Lateral Defections for Cast In-situ Bored Piles
7.3
67
Comparison of Measured and Calculated Lateral Defections for Driven Piles
7.2
66
Spreadsheet of CLM’s Ground-Line Deflection Formulation (Part 2 of 2)
7.1
64
Spreadsheet of CLM’s Ground-Line Deflection Formulation (Part 1 of 2)
6.2b
63
Spreadsheet of Broms’ Ground-Line Deflection Formulation (Part 2 of 2)
6.2a
60
Spreadsheet of Broms’ Ground-Line Deflection Formulation (Part 1 of 2)
6.1b
60
Plot of Lateral Deflection for TP2 at Site 3 from LSDTs and Inclinometer Measurements
6.1a
PAGE
77
Comparison of Measured and Calculated Lateral Defections for Cast In-situ Bored Piles in Cohesionless soil
7.4
Comparison of Measured and Calculated Lateral Defections for Cast In-situ Bored Piles in Cohesive soil
7.5
79
79
Comparison of Measured and Calculated Lateral Defections for 600mm Diameter Spun Piles in Site 1, Jimah, Negeri Sembilan
7.6
81
Comparison of Measured and Calculated Lateral Defections for 600mm Diameter Spun Piles in Site 2, Tanjung Bin, Johor
A.1
Location Plan for the Test Piles No. TP1, TP2, TP3c and TP4
A.2
81
90
Set-Up/Arrangement and Instrumentation Plan for TP1 and TP2
101
xvi FIGURE NO.
A.3
TITLE
Plan View on Set-Up/Arrangement and Instrumentation for TP1 and TP2
A.4
PAGE
102
Set-Up/Arrangement and Instrumentation Plan for TP3c and TP4
109
B.1
Location Plan for the Test Piles No. TP2a and TP2b
112
B.2
Set-Up/Arrangement and Instrumentation Plan for TP2a and TP2b
B.3
119
Set-Up/Arrangement and Instrumentation Plan for TP2a and TP2b
120
C.1
Location Plan for the Test Piles No. TP1 and TP2
122
C.2
Set-Up/Arrangement and Instrumentation Plan for TP1 and TP2
128
xvii
LIST OF SYMBOLS
a1, a2
Constant for Load-deflection and Moment-deflection
b1, b2
Exponent for Load-deflection and Moment-deflection
cu
Undrained shear strength
Cpφ
Passive pressure factor
D, d
Diameter
e
Height of the pile from the point of application of the load to the ground surface
Ep
Elastic modulus of the pile
fcu
Grade of concrete
H
Horizontal force or applied lateral load
Icircular
Moment of inertia of a solid circular cross section
Ip
Moment of inertia of the pile
k, k1
Coefficient of subgrade reaction
k∞
Coefficient of subgrade reaction
Kp
Rankine Coefficient of Passive Resistance
K0
Coefficient of subgrade reaction
L
Total pile length from pile cut-off level
m1, m2
Constant for Characteristic Load and Moment
Mc
Characteristic Moment
Mp
Equivalent moment
Mt
Moment
nh
Coefficient of modulus variation
n1
Coefficient of compressive strength of the soil
n2
Coefficient of material forming the pile
Pc
Characteristic Load
Pm
Equivalent load
xviii Pt
Applied lateral load
r1 , r2
Exponent for Characteristic Load and Moment
R1
Moment of inertia ratio
su
Undrained shear strength
y, yt
Ground-line deflection
ycomb
Average ground-line deflection
ytm
Ground-line deflection due to applied moment
ytp
Ground-line deflection due to applied load
ytmp
Ground-line deflection due to applied moment plus equivalent moment
ytpm
Ground-line deflection due to applied load plus equivalent load
∝
Factor
β
Coefficient of pile length
ε50
Axial strain at 50% of the soil strength
φ'
Effective friction angle
γ
Unit weight of soil
γb
Bulk unit weight of soil
γw
Unit weight of water
η
Coefficient of pile length
λ1, λ2
Dimensionless parameter for Characteristic Load and Moment
σp
Passive pressure of the soil
xix
LIST OF APPENDICES
APPENDIX
A
TITLE
PAGE
Test Pile Details for 1050mm Diameter Cast Insitu Bored Piles (TP1 and TP2) and 600mm Diameter Spun Piles (TP3c and TP4)
86
A.1
1050mm Diameter Cast In- situ Bored Piles
88
A.2
600mm Diameter Spun Piles
B
Test Pile Details for 600mm Diameter Spun Piles (TP2a and TP2b)
C
101
108
Test Pile Details for 1050mm Diameter Cast Insitu Bored Piles (TP1 and TP2)
118
CHAPTER 1
INTRODUCTION
1.1
Background of Thesis
Most structures are subject to lateral loads as a result of wind, earthquake, impact, waves, and lateral earth pressure. If these structures are supported on deep foundations, the foundations have to be designed to cater for lateral loads. Thus, such foundations should be designed to satisfy three conditions: (1) the pile should be able to carry the imposed load with an adequate margin of safety against failure in bending; (2) The deflection for the foundation under load should not be larger than the tolerable deflection for the structure it supports; and (3) The soil around the pile should not be loaded so heavily that it reaches its ultimate load-carrying capacity.
In most cases considerations of bending moments and deflection govern the design, because the ultimate load carrying capacity of the soil is reached only at very large deflections. The ultimate capacity of the soil around the pile may not be fully mobilised, however, its response is nonlinear. As a result, the relationship among load, moment, and deflection for laterally loaded deep foundations are nonlinear. It is therefore important to base design of laterally loaded piles on methods of analysis that model the nonlinear behaviour of the soil-foundation system.
In recent years, extensive theoretical approaches for predicting lateral deflection or moment have been developed. For example, the subgrade reaction approach by Barber (1953) and Matlock and Reese (1960), the p-y curve method by
2 Reese (1977), finite-element method by Bowles (1988) which assumes the soil to be as in the Winkler model and the elastic continuum approach by Poulos and Davis (1980), Duncan, Evans and Ooi (1994), Zhang and Small (2000), and Shen and Teh (2002). These aforementioned methods, however, need complex computer programs to perform fully numerical analysis and this makes them less accessible to practicing engineers in the routine design.
1.2
Nature of the problem
The application of a lateral load to the top of a pile will result in the lateral deflection of the pile. The reactions that are generated in the soil should be such that the equations of static equilibrium are satisfied, and the reactions should be consistent with the deflections. Also because no pile is completely rigid, the amount of pile bending must be consistent with the soil reactions and the pile stiffness.
Thus, the problem of the laterally loaded pile is a “soil-structure-interaction” problem. The solution of the problem requires that numerical relationships between pile deflection and soil reaction be known and that these relationships be considered in obtaining the deflected shape of the pile.
The problem seems formidable; however, two technological advances have allowed the problem to be solved with relative ease. Instrumentation that enables strains to be read remotely has made possible the determination of soil response during the testing of full-scale piles. And computer allows the deflected shape of a pile to be computed rapidly and accurately even though the soil reaction against the pile is a nonlinear function of pile deflection and depth below the ground surface.
3 1.3
Influence of Analytical Method on Engineering Practice
Some engineering practices employ the rational method for design of piles under lateral loading. No formal survey have been made, but informal conversations with a number of engineers indicate that one or more of the following approximate methods are currently in use: (1) assignment of a nominal lateral load for vertical piles as recommended in building codes; (2) use of raked piles where the horizontal component of the axial load balances the horizontal forces; and (3) making computations with the Broms’ method. The use of the rational method should lead to improvement in designs. However, for some major projects, load tests to ascertain lateral capacities are advisable.
If the rational method is used to get the response of a pile, structural engineers will have sufficient information to design the pile foundation to sustain the required loads. Combined stresses can easily be computed and reinforcement can be employed at proper positions along a pile. The reinforcement for combined stresses can consist of additional reinforcing steel or perhaps an increased diameter in some instances. If a portion of the pile extends above the ground level, the computer solution can be employed to investigate the possibility of buckling.
The approximate methods probably lead, in almost all instances, to an overdesign with regard to lateral loading. This overdesign results in increased cost. If there is an underdesign of a pile that is subjected to lateral loading, the result will be excessive deflection or a complete collapse of the system.
Thus, five common methods are available for the solution of a single pile under lateral load.
These are: elastic method, curves and charts, static method
(Broms’ method), computer method (nonlinear soil response), and dimensionless curves.
4 1.4
Aim and Objective of the Thesis
The aim of this thesis is to provide a simple and easy method to analysis the ground-line deflection for i) Single piles, ii) Long elastic pile, which the embedded pile length is more than four (4) times of stiffness factor of pile and soil, and iii) Free-head or unrestrained piles, which free rotation occurs at the head.
In order to achieve the aim of the thesis, three objectives have been identified: i) To compare the obtained theoretical results with the field test results. ii) To compare the results based on pile installation methods in cohesionless soil. iii) To compare the results based on types of soil for cast in-situ bored piles.
Therefore, two simple methods of analysis namely Broms’ method and Characteristic Load Method (CLM) have been selected to analyse the ground-line deflection to achieve the aims and objectives of the thesis. The calculated results will be compared with the available test data obtained from full-scale instrumented test piles in Malaysia.
1.5
Scope
The instrumented full-scale static load test were carried out for three various sites from West Coast of Peninsular Malaysia. The locations for the selected sites of the study are as shown in Figure 1.1.
5
KLIA Jimah Tg.Bin
Figure 1.1:
Location of Test Piles Site
Since the soil near the top of pile is most important with regard to response to the lateral load, the point of reference to classify the type of soil is terminated at the depth of fixity for lateral deflection which is 1.8 times of pile stiffness factor or 8 diameters of the piles below ground surface. All piles and soil parameters obtained from the test field were used in design analyses of Broms’ method and CLM. The lateral deflections at ground-line were calculated based on the type of pile and soil for comparison purposes.
6 1.6
Important of Thesis
The comparison between the selected design methods with measured data from instrumented full-scale static load test for deflection of laterally loaded piles could assist geotechnical engineer in adopting a more appropriate method in design of piles under lateral loading.
In Malaysia, many engineering practices employ the rational method of Broms or using sophisticated computer software for designing and analyse the laterally loaded piles. The results obtained from this thesis will provide geotechnical engineers an option of selecting a simple, quick and easy examine solution.
CHAPTER 2
LITERATURE REVIEW
2.1
Background
The ultimate resistance of a vertical pile to a lateral load and the deflection of the pile as the load builds up to its ultimate value are complex matters involving the interaction between a semi-rigid structural element and the soil, which deforms partly elastically and partly plastically.
Taking the case of a vertical pile
unrestrained at the head, the lateral loading on the pile head is initially carried by the soil close to the ground surface. At a low loading the soil compresses elastically but the movement is sufficient to transfer some pressure from the pile to the soil at a greater depth. At a further stage of loading the soil yields plastically and transfers its load to greater depths.
Figure 2.1:
Long Vertical Free-head Pile under Horizontal Load
8 The failure mechanism of an infinitely long pile is failure takes place when the pile fractures at the point of maximum bending moment. The passive resistance of the lower part of the pile is infinite, and thus rotation of the pile cannot occur as a short rigid pile, the lower part remaining vertical while the upper part deforms to a shape shown in Figure 2.1.
The pile head may move horizontally over an appreciable distance before failure of the pile occurs, to such an extent that the movement of the structure supported by the pile or pile group exceeds tolerable limits.
Therefore, have
calculated the ultimate load and divided it by the appropriate safety factor, it is still necessary to check that the permissible deflection of the pile is not exceeded.
Quite extensive research has been undertaken on the bending moment and deflection of piles to lateral loading but this research has not yielded any simple design method which can be universally applied to any soil or type of pile. There are many inter-related factors. The dominant one is the pile stiffness, which influences the deflection and determines whether the failure mechanism is due to flexure followed by the failure in bending of a long flexible pile. The type of loading, whether sustained (as in the case of earth pressure transmitted by a retaining wall) or alternating (say, from reciprocating machinery) or pulsating (as from the traffic loading on a bridge pier), influences the degree of yielding of the soil. External influences such as scouring around piles at sea-bed level, or the seasonal shrinkage of clay soils away from the upper part of the pile shaft, affect the resistance of the soil at a shallow depth.
9 2.2
Broms’ Method
2.2.1
Introduction
Broms developed comprehensive procedures for the design of piles in cohesive and cohesionless soils and his method has been widely used. The method was presented in papers published in 1964 (Broms, 1964a, 1964b).
2.2.2
Concepts Employed in Broms’ Method
Broms emphasised the computation of the lateral loading at which a pile would fail.
The equations were proposed for computing the ultimate lateral
resistance of cohesive or cohesionless soils as a function of depth and failure load. Broms has assumed that the soil profile is idealised and there is a linear relationship between load and deflection based on theory of subgrade reaction.
The theory of subgrade reaction, in which there is a linear relationship between load and deflection, was proposed for computing the deflection. It was suggested that the computations of deflection were valid only for a load of up to onethird to one-half of the ultimate load.
10 2.2.3
Broms’ Deflection Equations
2.2.3.1 Piles in Cohesionless Soil
Broms suggested that the lateral deflections at the ground-line y of a single, long unrestrained pile in cohesionless soil can be expressed as follow:
y=
2.4 H (1 + 0.67eη )
(
nh 3 5 E p I p
)2 5
(2.1)
where H = horizontal force; e = height of the pile from the ground surface to the point of application of the load; nh = coefficient of modulus variation; Ep = elastic modulus of the material forming the pile shaft; Ip = moment of inertia of the crosssection of the pile shaft and
η =5
nh EpI p
(2.2)
2.2.3.2 Piles in Cohesive Soil
The lateral deflection at the ground-line of the free-head pile in cohesive soil is
y=
2 Hβ (eβ + 1) k∞ D
(2.3)
where k∞ = coefficient of subgrade reaction; D = the pile width; and
β =4
kD 4E p I p
(2.4)
where k = coefficient of subgrade reaction. The coefficient of subgrade reaction k∞ is calculated from k ∞ =∝ K 0 / D
(2.5)
where K0 is a coefficient of subgrade reaction and ∝= n1 × n2
(2.6)
11 The factors n1 is the compressive strength of the soil and n2 is the material forming the pile as shown in Table 2.1 and 2.2.
Table 2.1:
Table 2.2:
Values of coefficient n1 (after Broms, 1964a) Shearing strength (kN/m2)
Coefficient n1
< 27
0.32
27 – 107
0.36
> 107
0.40
Values of coefficient n2 (after Broms, 1964a) Material forming pile
Coefficient n2
Steel
1.00
Concrete
1.15
Wood
1.30
2.3
Characteristic Load Method
2.3.1
Introduction
Evans and Duncan (1982) developed the use of dimensionless variable to represent a wide range of real conditions by means of a single relationship. This method closely approximates the results of nonlinear p-y analyses. It was developed by performing nonlinear p-y analyses for a wide range of free-head and fixed-head piles and drilled shafts in cohesive and in cohesionless soils, and representing the results in the form of relationships among dimensionless variables.
12 2.3.2
Concepts of Characteristic Load Method
The Characteristic Load Method (CLM) formulation is based on dimensionless relationships related to load and moment.
To form these
dimensionless relationships, loads are divided by a characteristic load Pc, moments are divided by a characteristic Mc, and deflections are divided by the pile width D. The expressions for the characteristic load and the characteristic moment were developed by repeated trial. They embody the properties of both the deep foundation (diameter and flexural stiffness) and the soil (strength and stress-strain behaviour) that determine the way that the pile and the soil respond to lateral loads.
It was suggested that the computation of deflection were valid only for pile that are long enough so that their behaviour is not affected to any significant degree by their length. Maximum lengths necessary to satisfy this criterion depend on the relative stiffness of the pile in relation to the stiffness of the soil in which it embedded. Minimum lengths for a number of different conditions are given in Table 2.3.
If the length of a pile is less than listed in Table 2.3, deflections will differ from the values calculated using the CLM.
Table 2.3:
Minimum Pile Lengths for Characteristic Load Method
Soil Type
Criterion
Minimum Length
Clay
EpRI/su = 100,000
6 diameter
Clay
EpRI/su = 300,000
10 diameter
Clay
EpRI/su = 1,000,000
14 diameter
Clay
EpRI/su = 3,000,000
18 diameter
Sand
EpRI/(γDφ'Kp) = 10,000
8 diameter
Sand
EpRI/(γDφ'Kp) = 40,000
11 diameter
Sand
EpRI/(γDφ'Kp) = 200,000
14 diameter
13 2.3.3
Characteristic Load Method Equations
2.3.3.1 Dimensionless Relationship with Characteristic Load Pc and Moment Mc
The characteristic load and moment that form the basis for the dimensionless relationships are given by the following expressions: ⎛ σp ⎞ ⎟ Pc = λ1 D E p R1 ⎜ ⎜ E p R1 ⎟ ⎝ ⎠
m1
2
⎛ σp ⎞ ⎟ M c = λ2 D E p R1 ⎜ ⎜ E p R1 ⎟ ⎝ ⎠ 3
R1 =
(ε 50 )r1
m2
(ε 50 )r2
Ip
(2.7)
(2.8)
(2.9)
I circular
For bitter clay, λ1 = 0.14 n1 , and
For plastic clay and sand, λ1 = λ2 = 1.00.
λ2 = 0.14 n2 . For cohesive soil,
σ p = 4.2su
(2.10)
For cohesionless soil, ⎛ ⎝
σ p = 2C pφ γD tan 2 ⎜ 45° + C pφ =
φ′ 10
φ′ ⎞ ⎟ 2⎠
(2.11) (2.12)
where R1 = moment of inertia ratio = 1.70 for solid square cross-sections; Icircular = moment of inertia of a solid circular cross section; λ1 and λ2 = dimensionless parameters; σp = passive pressure of the soil; ε50 = axial strain at which 50% of the soil strength is mobilised, obtained from triaxial compression tests or from Table 2.4; su = undrained shear strength from the ground surface to a depth of 8D; φ’ = effective friction angle (deg) from ground surface to a depth of 8D; Cpφ = passive pressure factor; and γ = unit weight of soil from ground surface to a depth of 8-pile width. If
14 the water table is within this zone, average of γ and γ b = γ − γ w be used. The exponents m1, r1, m2 and r2 are shown in Table 2.5.
Table 2.4:
Typical ε50 values (Matlock, 1970)
ε50
Soil Type
Table 2.5:
Disturbed, remoulded, soft clay
0.020
Normally consolidated medium clay
0.010
Brittle, stiff, sensitive clay
0.005
Medium dense sand with little or no mica
0.002
Values of the exponents m and r (Evans and Duncan, 1982) For Pc Soil Type
For Mc
m1
r1
m2
r2
Cohesive soil
0.683
-0.22
0.46
-0.15
Cohesionless soil
0.570
-0.22
0.40
-0.15
Three main groups of dimensionless relationships are used in the CLM: Load-deflection, moment-deflection, and load-moment. Different relationships for each group are used for cohesive and cohesionless soils. A single-term exponential equation in the form of y = axb where a is a constant and b is an exponent, is used for the dimensionless relationships. The coefficients a and b are obtained from a power regression analysis. ⎛P yt = a1 ⎜⎜ t D ⎝ Pc
b
⎞1 ⎟⎟ ⎠
⎛M yt = a 2 ⎜⎜ t D ⎝ Mc
⎞ ⎟⎟ ⎠
With a and b deduced from Table 2.6.
(2.13)
With a and b deduced from Table 2.7.
(2.14)
b2
In these equations, yt is the ground-line deflection, D the pile width, Pt the lateral load applied at top of pile, Mt the moment applied at the top of pile.
15 Table 2.6:
Constants
for
y t D = a1 (Pt Pc )b1
Load-deflection
equations
Constant
Cohesive Soil
Cohesionless Soil
a1
50
119
b1
1.822
1.523
(Brettmann & Duncan, 1996)
Table 2.7:
Constants for Moment-deflection equations y t D = a 2 (M t M c )b 2
(Brettmann & Duncan, 1996) Constant
Cohesive Soil
Cohesionless Soil
a2
21
36
b2
1.412
1.308
2.3.3.2 Deflection due to Combined Load and Moment
Given that the response is nonlinear, simply acting the deflections caused by the lateral load and the moment is not sufficient. Instead, the nonlinear effects are taken into account by using a nonlinear superposition procedure.
The first step in the nonlinear superposition is to calculate the deflections that would be caused by the applied load Pt acting alone ytp and the applied moment Mt acting alone ytm using equations listed in the previous section.
The second step is to determine the equivalent load Pm that can cause the same deflection ytm as the moment, and the equivalent moment Mp that can cause the same deflection ytp as the load.
16 The third step is computing the average ground-line deflection ycomb of ytpm caused by the sum of the real load Pt plus the equivalent load Pm, and ytmp caused by the sum of the real moment Mt plus the equivalent moment Mp using the equations of the previous section. It is calculated using the equation y comb =
y tpm + y tmp 2
(2.15)
CHAPTER 3
INSTRUMENTED FIELD LOAD TEST
3.1
Introduction
The need for the instrumented field load test arose because the database for laterally loaded piles in Malaysia was limited and the design methods in use were generally thought to be conservative. In addition, there was a trend within the industry towards more frequent use of vertical piles to support lateral load. With the consequential increases in pile wall thickness, the development of a more soundly based lateral load-deflection design method becomes more important.
The main objective of the instrumented load test is to establish the following: i) To serve as a proof test to ensure that failure does not occur before a selected proof load is reached, this proof load being the minimum required factor times the design working load. ii) To determine the ultimate load carrying capacity as a check on the value calculated from static approaches, or to obtain back figured soil data that will enable other piles to be designed. iii) To determine the load-deflection behaviour of a pile, especially in the region of the anticipated design working load. This data can be used to predict group deflection and deflection of other piles.
18 3.2
Selection of Test Pile
The type of pile and its size is selected based on the similar properties of the piles proposed for the particular project site. The lateral load test is to confirm the pile design at a particular project site, thus, the diameter, stiffness and length of the test pile is installed as close as possible to similar properties of the work piles.
Factors of the selection of the test pile have been given into consideration to the soil conditions, the type of instrumentation to be employed, the method of installing instrumentation in the pile, the magnitude of the desired ground-line deflection and the nature of the loading.
Consideration are also given to increasing the stiffness and moment capacity of the test pile in order to allow the test pile to be deflected as much as reasonable as to obtain the information on the soil response.
3.3
Installation of Test Pile
The test pile is installed as closely as possible to the procedure proposed for the work piles. It is well known that the response of a pile to load is affected considerably by the installation procedure, thus, the detailed procedure used for pile placement is important.
For the case of a test pile in cohesive soil, the test begins after the dissipation of the excess pore water pressure which occurred due to the placement of the pile. On the other hand, for the test pile in cohesionless soil, the test begins after the rearrangement of the soil particles which occurred due to densification of the soil during installation of the pile.
19 The installation of the pile that has been instrumented with inclinometer for the measurement of deflection along the length of pile have been consider the possible damage of the instrumentation due to pile driving or other installation effects. Piling installation procedure adopted is consistent with practice methods commonly used in Malaysia. During the installation of the test pile, care is also taken to reduce the soil disturbance near the ground surface.
3.4
Testing Procedures
The standard testing procedures for pile testing is follow the guideline given in ASTM Standard D 3966-90 “Standard Method of Testing Piles under Lateral Loads” or Eurocode 7. Two principles have guided the testing procedure: 1) the loading is consistent with the expected for the work piles; and 2) the testing arrangement in such that the deflection, rotation, bending moment, and shear at the ground-line (or at the point of load applied) are measured or computed. Typically, piles are tested up to minimum 200% of the design lateral load with load increments of 25% of the test load for standard loading schedule for a loading duration of 15 to 30 minutes.
Two test piles with inclinometer installed in each pile are installed with spacing that the pile-soil-pile interaction is minimised.
The piles are tested
simultaneously as shown in Figure 3.1. The results obtained from the test are compared and it gives the designer some idea of the natural variations that can be expected in pile performance.
With regard to loading, static maintained loading/unloading is adopted. The load is applied at the proposed pile cut-off level and is loaded based on a proposed loading schedule, readings taken, and the same load is maintained for a period of time with reading taken as per proposed loading schedule. Then, a larger load is applied and the procedure repeated.
20
I-Beam
Load Cell
Inclinometer
Figure 3.1:
Hydraulic Jack
Pile
Typical Set-up for Simultaneous Testing of Two Piles under Lateral
Loading
The test piles are laterally loaded using hydraulic jack. The jack is operated by an electric pump with an automatic controller. The applied load is indicated by calibrated load cell with connected to a data logger. Pressure gauge reading is also recorded as back-up counter-checking purpose. This is to avoid override of the automatic system in case of malfunction.
Other than taking deflection reading from the inclinometer, electronic displacement transducers is mounted to the reference beams with its plungers placed horizontally against glass plates fixed on the flat vertical plane at each of the piles as shown in Figure 3.2. Horizontal scale rules also fixed to the piles side sighted by a precise level instrument. The horizontal scales are also provided on the reference beams to monitor any movement during load testing.
The load cells and electronic displacement transducers are logged automatically using a data logger or multi-logger software at 5 minutes intervals for close monitoring during loading and unloading steps. Only precise level reading will be taken manually.
21
Pile Glass Plate Sensitive Level Bubble Dial Gauge or Electronic Device
Hydraulic Jack and Load Cell
Reference Beam
Figure 3.2:
3.5
Device for Measuring Pile-Head Displacement
Interpretation of Data
The interpretation of data from the test is straightforward process. Plots are made of lateral deflection versus applied lateral load at pile top which measured by inclinometers and electronic displacement transducers.
CHAPTER 4
METHODOLOGY
4.1
Introduction
To achieve the objectives of this thesis, the sequence of tasks carried out must be clearly outlined in order to achieve results systematically. In order to achieve this goal, meeting and discussions were carried out with the Supervisor to establish the fundamental objective of this study.
Once the objectives of the study have been identified, in depth literature review is required to obtain the knowledge about the thesis. The scope of the study will then be determined with reference to time and coverage of the thesis.
During the preliminary stage of the thesis, instrumented full-scale lateral load test results have been obtained. The type of data collected for this thesis shall be relevant and not limited to soil and pile parameters from the instrumented test piles, lateral deflection results from the field test, site investigation data, etc.
The
outcomes from the instrumented full-scale lateral load test ensure that the objectives are met and the next phases of the thesis are established in a continuous manner. Figure 4.1 comprises of the flow chart from this thesis.
23
Data Collection a. Soil and pile parameters from instrumented test piles b. Lateral deflection results from instrumented field tests
Data Analysis Lateral deflection analyses using Broms’ Method and Characteristic Load Method
Data Presentation The graphs between the applied load verses lateral deflection of Broms’ Method, Characteristic Load Method and field test results based on types of soil, pile installation methods are plotted.
Discussion The comparison between the theoretical analyses and field test results based on types of soil, pile installation methods are tabulated. Figure 4.1: Sequence Used to Carry Out the Comparison of the Calculated and
Measured Lateral Deflection of the Test Piles
4.2
Data Collection
The soil and pile parameters were obtained from the instrumented field test reports from various sites in Peninsular Malaysia. The summary of the projects site involved which describes the background of the project, scope of works, purpose of the project, installation details of the test piles, subsoil information from site investigation results, testing details, loading schedules was discussed in Chapter 5 of Data Collection. The borehole data obtained from site investigation reports consists of the description of the soil type with reference to depth. The data also provides the samples of soil, which are sent to the laboratory to obtain essential soil parameters.
24 The subsoil data obtained, was used to analysis the ground-line deflection of the test piles. The expected results will achieve a higher accuracy if the numbers of instrumented full-scale tests available are many.
4.3
Data Analysis
4.3.1
Calculating Ground-line Deflection using Method of Broms
Once the soil and pile parameters of the instrumented load test is obtained, the ground-line deflection for the test pile is calculated using method of Broms as stated in Equation 2.1 and Equation 2.3 for cohesionless soil and cohesive soil respectively as previously described in Section 2.2.3:
For long elastic, free-head pile in cohesionless soil: y=
2.4 H (1 + 0.67eη )
(
nh 3 5 E p I p
)2 5
For long elastic, free-head pile in cohesive soil:
y=
2 Hβ (eβ + 1) k∞ D
The relevant parameters that wholly depend on the type of soil will be calculated as described in Section 2.2.3. For each test pile, the ground-line deflection will be calculated using Broms’ equation.
25 4.3.2
Calculating Ground-line Deflection using Characteristic Load Method
The same method as Broms’ method describe above will be used to calculate the ground-line deflection for the test pile but this time using CLM equation as an alternative. The formulation developed by Evan and Duncan is as stated in Equation 2.15 previously: y comb =
ytpm + ytmp 2
The equation above is comparatively different from Broms’ equation as CLM had incorporated the lateral deflection caused by the applied lateral load, moment, equivalent load due to the moment, and equivalent moment due to the applied lateral load. In this thesis, that comparison will be utilised to establish a better perspective or comparison between both the equations during analysis of the results.
4.4
Data Presentation
The results obtained from Data Analysis will be tabulated and plotted in a graphical form between Applied Load versus Lateral Deflection for the test piles from various sites in Malaysia. The load-deflection plots will consist herewith the results obtained from equations developed by Broms, Evan and Duncan, and measured values from the instrumented field test.
The graph was presented based on types of soil and pile installation methods. The graph will be plotted with X-axis consisting of the Applied Load and the Y-axis consisting of the Lateral Deflection.
26 4.5
Data Interpretation and Results
From the graph obtained, an interpretation of the results was developed by establishing a trend line that coincides with most of the formulated points. The comparison can then be made between the theoretical analyses and field test results with respect to their type of soil and method of pile installation.
A proper table clearly indicating the accuracy of the theoretical methods against measured results will be established and summarised.
CHAPTER 5
DATA COLLECTION
5.1
Introduction
The sites selected for data collection from west coast of Peninsular Malaysia for both cohesionless and cohesive type of soils; and, driven and cast in-situ bored piles. In this topic, the geological background of the site, the scope of works, static maintained load test method carried out and instruments used were described and discussed. The types of data collected are the subsoil parameters, pile type, pile parameters, load test method and measured lateral deflection of the test piles.
For sites as shown in Figure 1.1 with cohesionless soil (hydraulic sand fill) and both the driven and cast in-situ bored piles, the locations of the sites are Jimah, Negeri Sembilan and Tanjung Bin, Johor. On the other hand, for site with cohesive soil data and cast in-situ bored piles, the location of the site is KLIA, Selangor. The test piles and site details are tabulated as shown in Table 5.1. As a summary, the soil and pile parameters collected from the sites were tabulated for viewing.
28 Table 5.1:
Summary of Site Data Pile
Site
Pile
Project Title
No.
Dia.
Type
Pile No.
Soil Type
(mm)
1.
1400MW Coal Fired Power
Bored
Plant,
Piles
Jimah,
Negeri
Sembilan
Spun
1050
TP1 & TP2
Sand
600
TP3c & TP4
600
TP2a & TP2b
Sand
1050
TP1 & TP2
Clay
Piles 2.
3.
2100MW Coal Fired Power
Spun
Plant, Tanjung Bin, Johor
Piles
A-380
Hangar/Workshop
Bored
Facility at MAS Complex,
Piles
KLIA, Sepang, Selangor
5.2
Site 1 – 1400MW Coal Fired Power Plant Project in Jimah, Negeri Sembilan
5.2.1
Introduction
For Site 1, the instrumented lateral load tests were carried out for the test piles for the construction of 2 units of 700MW coal-fired power plant in Jimah, Negeri Sembilan.
The main objective of the tests is to verify the pile design
parameters including the deflection and working capacity of the piles.
29 5.2.2
Geological Background of the Site
The site is located at 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 meter and 5 meters below the Malaysian Land Survey Datum (MLSD, approximate Mean Sea Level).
References to the geological map of the site and its surroundings (Geological Survey Malaysia, 1985) show it to be 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
DEPTH (m)
Period.
SOIL TYPE
SPT Nvalue
SPT N - Value (per 30cm) 18 10
20
30
40
50
0 5
10
Loose to dense, fine to coarse, SAND (Hydraulic fill)
10-40
(10.50m)
15
20
Very soft to medium stiff, Stiff CLAY
0-9
25
9 7
(28.60m) 20
30 Very stiff, sandy SILT
15
15-25
35 (39.00m) 40 Very dense, gravelly SAND (residual soil) (43.00m) Hard, sandy SILT 45 (residual soil) (46.60m)
23 20
68-83
68 83
60-188
60 68 188
50 55
Figure 5.1:
Typical Subsoil Profile (Borehole ref. ABH-27)
30 Site investigation, including boreholes and piezocone tests, later confirmed the geological succession at the as Quaternary deposits overlying a weathered profile of meta-sedimentary rocks (Figure 5.1).
Prior installation of the test piles, site preparation works involving land reclamation and soil improvement works with hydraulic sand filling, installation of prefabricated vertical drains and surcharging/ preloading were carried out.
5.2.3
Appreciation of Subsoil Condition after Reclamation
Based on the available site investigation factual report, the site is underlain by some 8 meters of sand fill followed by a transition zone of 1 meter to 2 meters thick comprising a mixture of hydraulic sand and in-situ soils. This is further underlain by Quaternary deposits of very soft to soft clay of up to about 16 meters thick. Residual soils comprising medium stiff to hard clayey sandy silt with occasional dense sand layer can be encountered at greater depths.
Sedimentary bedrocks consisting
interbedded Sandstones and Shales can be encountered at reduced levels ranging from about RL-36m to RL-48m MLSD.
5.2.4
Scope
The scope is to carry out the instrumented static maintained load test for 1050mm diameter cast in-situ bored piles and 600mm diameter spun piles. The main objective of the instrumented static maintained load test is to establish the response/lateral deflection profile of the test piles under applied lateral loadings for the use in the design of working piles which are to be constructed in soil strata having same geological structure. The load-deflection relationship under loading from measurement results will be presented both in tabulated and graphical format for easy assessment.
31 5.2.5
Location of the Test Piles and Subsurface Information
Test piles location plan, installation records and the test set-up/arrangement for lateral test piles are attached in Appendix A. The relevant site investigation boreholes information are also attached in Appendix A for ease of reference and the subsoil information from the site investigation are shown in Table 5.2.
Table 5.2:
Summary of Subsoil Information for Site 1 Unit Weight of Soil, γ Friction Angle, φ' Undrained Shear Strength, cu Coefficient of modulus variation, nh
18 kN/m3 35° 0 1250 kN/m3
32 5.2.6
Test Piles Installation
5.2.6.1 1050mm Diameter Cast In-situ Bored Piles Installation
The test piles have a nominal diameter of 1050mm and were constructed by a local bored piling company using mechanical boring machine. For test piles no. TP1 and TP2, the top 19 meters was temporary cased and from 19 meters downwards, the hole was stabilised using bentonite slurry. The test pile no. TP1 and TP2 were bored to a depth of 47.7 meters and 50.6 meters respectively from the ground surface and were concreted by trimie method. The characteristic cube strength of the concrete for these cast in-situ bored piles was 40 N/mm2 with a slump of more than 175 mm. The final penetration depth for test pile no. TP1 and TP2 were 42.95 meters and 45.95 meters respectively from RL +1.45m MLSD excavated testing platform level. The summary of the piles information are shown in Table 5.3.
Table 5.3:
Summary of Pile Information for 1050mm Diameter Cast In-situ
Bored Piles at Site 1 TP1
TP2
Pile Type
Bored Pile
Bored Pile
Pile Diameter
1050 mm
1050 mm
Grade of Concrete
40 N/mm2
40 N/mm2
Pile Penetration Length from Cut-Off Level
42.95 m
45.95 m
Free Standing Length
4.75 m
4.65 m
Total Pile Length
47.70 m
50.60 m
28000 kN/m2
28000 kN/m2
Moment of Inertia
0.05967 m4
0.05967 m4
Testing Platform Level
RL +1.45 m
RL +1.45 m
Lateral Load Applied at Level
RL +1.95 m
RL +1.95 m
Pile Number
Modulus of Elasticity
33 5.2.6.2 600mm Diameter Spun Pile Installation
The test piles have a nominal diameter of 600mm were constructed by a local piling company using 11 tons hydraulic hammer. For test piles no. TP3c and TP4, the top 12 meters was pre-bored and from 12 meters downwards was driven with Xpile shoe starter. The 2nd and 3rd extensions were coated with bitumen to minimise the down drag forces. The test piles no. TP3c and TP4 were driven to set and with the penetration depth of 34.75 meters from RL +1.45m MLSD excavated testing platform level. The summary of the piles information are shown in Table 5.4.
Table 5.4:
Summary of Pile Information for 600mm Diameter Spun Piles at
Site 1 TP3c
TP4
Spun Pile
Spun Pile
600mm
600mm
80 N/mm2
80 N/mm2
Pile Penetration Length from Cut-Off Level
34.75m
34.75m
Free Standing Length
1.05m
1.05m
Total Pile Length
35.80m
35.80m
36000 kN/m2
36000 kN/m2
Moment of Inertia
0.00329 m4
0.00329 m4
Testing Platform Level
RL +1.45m
RL +1.45m
Lateral Load Applied at Level
RL +1.90m
RL +1.90m
Pile Number Pile Type Pile Diameter Grade of Concrete
Modulus of Elasticity
5.2.7
Proposed Instrumentation
In order to obtain the load-deflection along the piles, inclinometer was installed in each pile. Inclinometer tubings were terminated at pile toe, with top of tubing extended to 0.3 meter above top of pile. The location of each inclinometer is indicated in the sketch showing test assembly in Appendix A.
34 5.2.8
Pile Movement Monitoring System
For each pile, the lateral deflection was monitored using:
i) Two numbers of Linear Variation Displacement Transducers (LVDTs) mounted to a reference frame on the tension side of the pile, with plunger pressing horizontally against a prepared flat vertical surface at each of the pile. LVDTs reading were logged automatically at two minutes interval using Micro-10 datalogger.
ii) The full lateral deflection profile of the pile was measured with the aid of an inclinometer using Geokon Model 6000 biaxial inclinometer probe and Geokon Model GK-603 inclinometer logger.
Pile deflections in the piles were measured using the inclinometer at 0.5m intervals at the end of each loading/unloading step. During holding period for each cycle, additional readings were also taken.
5.2.9
Static Maintained Load Tests
For the instrumented test piles, static maintained load tests were carried out and were loaded to more than two and a half times of its proposed design working load using test assembly as shown in set-up attached in Appendix A. In the set-up used, the test piles were laterally loaded at the proposed pile cut-off level using a double acting hydraulic jack which was operated by an electric pump. The applied load was indicated by calibrated vibrating wire load cell. Pressure gauge readings were also recorded as back-up counter checking purpose.
Three cycles load/unloading static maintained load tests were applied to these test piles about one month after the piles were installed. At the end of each cycle, the loads were maintained for one to two hours depending on the proposed loading
35 schedule attached in Appendix A before the loads were released.
LVDTs which
mounted on an independent support and inclinometers were to monitor the piles lateral movement. In addition the movements of the independent supports were also measured so that any movement of there supports can be corrected for the pile movement.
5.2.10 Test Results
5.2.10.1
Test Results for 1050mm Diameter Cast In-situ Bored Piles
Table 5.5 summarised the results of the three cycles static maintained load tests for 1050mm diameter cast in-situ bored piles. The Applied Load – Lateral Deflection plots of measured by both LVDTs and inclinometer (INCL) were shown in Figure 5.2 and Figure 5.3 for test piles TP1 and TP2 respectively.
36 Table 5.5:
Summary of the Lateral Deflection for 1050mm Diameter Cast In-situ
Bored Piles at Site 1 Cycle
Applied
Average
Lateral
Average
Lateral
Lateral
Lateral
Deflection
Lateral
Deflection
Load (kN)
Deflection
for TP1
Deflection
for TP2
for TP1
(INCL)
for TP2
(INCL)
(LVDTs)
(mm)
(LVDTs)
(mm)
(mm)
First
Second
(mm)
0
0
0
0
0
50
0.77
0.85
0.81
0.75
100
1.49
1.90
1.58
1.50
150
2.46
2.65
2.83
2.75
190
3.64
3.40
4.12
4.00
150
3.03
2.80
3.44
3.60
100
2.66
2.30
3.02
3.20
50
2.24
1.92
2.57
2.80
0
1.43
1.53
1.99
2.20
0
1.43
1.53
1.99
2.20
50
2.00
2.10
2.45
3.30
100
2.70
2.70
2.96
3.86
150
3.32
3.30
3.69
4.42
190
3.93
3.60
4.30
4.90
250
5.85
5.70
6.14
5.50
300
7.90
7.40
8.14
8.15
350
10.39
9.20
11.21
10.80
400
12.91
12.60
14.04
14.10
450
14.69
15.30
15.73
15.10
475
16.02
16.20
17.39
15.80
400
15.22
15.30
16.28
15.50
300
13.82
12.80
14.97
13.50
200
12.33
12.30
13.81
12.70
100
9.95
10.50
11.10
10.20
0
6.76
7.70
8.17
6.40
37 Cycle
Applied
Average
Lateral
Average
Lateral
Lateral
Lateral
Deflection
Lateral
Deflection
Load (kN)
Deflection
for TP1
Deflection
for TP2
for TP1
(INCL)
for TP2
(INCL)
(LVDTs)
(mm)
(LVDTs)
(mm)
(mm)
Third
(mm)
0
6.76
7.70
8.17
6.40
300
12.65
12.90
14.10
13.80
450
16.30
15.90
17.90
17.20
600
21.86
22.40
24.04
23.70
750
28.90
29.20
31.62
30.90
500
26.29
25.60
28.88
26.90
250
21.41
21.90
24.76
24.00
0
12.07
12.40
13.19
14.40
38
Applied Load vs Lateral Deflection (TP1) Applied Load, kN 0
100
200
300
400
500
600
700
800
0
5
Lateral Deflection, mm
10
15
20
25
30 LVDTs
INCL
35
Figure 5.2:
Plot of Lateral Deflection for TP1 at Site 1 from LVDTs and
Inclinometer Measurements
Applied Load vs Lateral Deflection (TP2) Applied Load, kN 0
100
200
300
400
500
600
700
0
5
Lateral Deflection, mm
10
15
20
25
30 LVDTs
INCL
35
Figure 5.3:
Plot of Lateral Deflection for TP2 at Site 1 from LVDTs and
Inclinometer Measurements
800
39 5.2.10.2
Test Results for 600mm Diameter Spun Piles
Table 5.6 summarised the results of the three cycles static maintained load tests for 600mm diameter spun piles. The Applied Load – Lateral Deflection plots of measured by both LVDTs and inclinometer (INCL) were shown in Figure 5.4 and Figure 5.5 for test piles TP3c and TP4 respectively.
40 Table 5.6:
Summary of the Lateral Deflection for 600mm Diameter Spun Piles at
Site 1 Cycle
Applied
Average
Lateral
Average
Lateral
Lateral
Lateral
Deflection
Lateral
Deflection
Load (kN)
Deflection
for TP3c
Deflection
for TP4
for TP3c
(INCL)
for TP4
(INCL)
(LVDTs)
(mm)
(LVDTs)
(mm)
(mm)
First
Second
(mm)
0
0.00
0.00
0.01
0.00
15
0.59
1.20
0.75
1.10
30
1.40
1.80
1.82
1.40
45
2.65
3.05
3.28
2.90
60
4.01
4.30
4.80
4.20
45
3.48
4.00
4.24
3.50
30
2.73
3.30
3.53
2.60
15
1.80
2.30
2.62
1.50
0
0.82
1.30
1.56
1.20
0
0.82
1.30
1.56
1.20
15
1.48
2.90
2.39
1.60
30
2.31
3.50
3.28
2.30
45
3.28
4.30
4.22
3.00
60
4.30
6.40
5.32
3.30
75
5.74
8.40
6.84
5.20
90
7.54
10.20
8.57
6.80
105
9.79
11.40
10.44
8.50
120
12.61
13.70
12.37
10.20
135
17.08
17.10
16.11
14.00
150
22.03
22.30
20.73
18.80
120
20.84
21.50
19.49
16.60
90
17.97
17.70
16.81
15.40
60
13.42
13.90
13.33
12.00
30
8.80
8.90
10.38
9.20
0
3.81
4.40
5.90
5.80
41
Cycle
Applied
Average
Lateral
Average
Lateral
Lateral
Lateral
Deflection
Lateral
Deflection
Load (kN)
Deflection
for TP3c
Deflection
for TP4
for TP3c
(INCL)
for TP4
(INCL)
(LVDTs)
(mm)
(LVDTs)
(mm)
(mm)
Third
(mm)
0
3.81
4.40
5.90
5.80
75
12.42
13.50
12.13
10.40
150
23.83
22.20
22.10
19.20
175
30.83
27.20
28.91
26.00
100
22.03
20.70
92.71
92.60
50
11.95
12.20
92.69
90.00
0
5.01
5.30
47.86
43.80
42
Applied Load vs Lateral Deflection (TP3c) Applied Load, kN 0
20
40
60
80
100
120
140
160
180
200
0
5
Lateral Deflection, mm
10
15
20
25
30 LVDTs
INCL
35
Figure 5.4:
Plot of Lateral Deflection for TP3c at Site 1 from LVDTs and
Inclinometer Measurements
Applied Load vs Lateral Deflection (TP4) Applied Load, kN 0
20
40
60
80
100
120
140
160
180
200
0 10
Lateral Deflection, mm
20 30 40 Load dropped drastically while deflection continued to increase. Pile seemed had been cracked.
50 60 70 80 90 LVDTs
INCL
100
Figure 5.5:
Plot of Lateral Deflection for TP4 at Site 1 from LVDTs and
Inclinometer Measurements
43 5.3
Site 2 – 2100MW Coal Fired Power Plant in Tanjung Bin, Johor
5.3.1
Introduction
For Site 2, the instrumented lateral load test was carried out for the test piles for the construction of 3 units of 700MW coal-fired power plant in Tanjung Bin, Johor. The main objectives of the test are to monitor the lateral deflection of the spun pile during the lateral load test and to verify the pile design parameters including the working capacity of the piles.
5.3.2
Geological Background of the Site
The site is located at the southern tip of Peninsula Malaysia. The coastal area is characterised by mangrove and mud flats, and the area of the site was formally used for fish farming, lying at approximately one meter above MLSD.
Boreholes and CPTu probing over the site identified the geological succession as some 20m of Holocene clay overlying older Alluvium and residual soils.
This succession is consistent with the coastal soils found extensively
elsewhere in the Region, including Singapore, the north coast of Java and Sumatra, and the west coast of Peninsula Malaysia.
The geological map of Peninsula Malaysia confirms the presence of Pleistocene Alluvium underlying the Holocene deposits, and consisting of gravel, sand, clay and boulder beds. Solid geology consists of the Bukit Resam Clastic member from the Upper to Middle Triassic age and Gunung Pulai volcanic member of Lower Triassic or older. The boreholes are consistent with the geological map, and identified Schist, Siltstone, Mudstone, Sandstone/Meta-Sandstone and Tuff/Meta-Tuff as the predominant constituents.
44 Prior installation of the test piles, site preparation works involving land reclamation and soil improvement works with hydraulic sand filling, installation of prefabricated vertical drains and surcharging/preloading were carried out. Maximum 15m thick of sand was filled to achieve 90% of primary settlement. After removal of surcharge, 5 to 8m of sand remains in place to attainment of a minimum platform level of RL+4.0m above MLSD.
5.3.3
Appreciation of Subsoil Condition after Reclamation
Based on the available site investigation factual report, the site is underlain by 3 meters to 8 meters of sand fill followed by a transition zone of 1 meter to 2 meters thick comprising a mixture of hydraulic sand and in-situ soil.
This is further
underlain by Quaternary deposits of very soft to soft clay of up to 13 meters to 18 meters thick. Residual soils comprising stiff to hard slightly sandy gravely clay/silt with occasional dense sand/gravel layer can be encountered at greater depths (Figure 5.6).
Sedimentary bedrocks consisting Tuff and interbedded Mudstones and
Sandstones can be encountered at reduced level ranging from about RL-28.5m to RL-50m MLSD.
5.3.4
Scope
The scope is to carry out the instrumented static maintained load test for 600mm diameter spun piles.
The main objective of the instrumented static
maintained load test is to establish the response/lateral deflection profile of the test piles under applied lateral loadings. The load-deflection relationship under loading from measurement results will be presented both in tabulated and graphical format for easy assessment.
DEPTH (m)
45
0 5
10
15
SOIL TYPE
SPT Nvalue
Medium dense, fine to coarse, SAND (Hydraulic fill)
20-27
(7.20m) Very stiff sandy CLAY (Alluvium) (8.50m)
18
Very soft to soft CLAY (Alluvium)
0-4
SPT N - Value (per 30cm) 18 10
20
30
40
50
18
2
20
4
(22.50m) 25
9
9
30 Firm to stiff CLAY (Residual Soil - Grade VI)
6-28
35
13 28
40
45
50
(41.00m) 50/9.5cm 50/3cm
Hard slightly gravelly SILT (Residual Soil - Grade VI)
50/5cm 50/9.5cm 50/3cm 50/2cm
50
(51.30m)
55
Figure 5.6:
5.3.5
Typical Subsoil Profile (Borehole ref. BBH-12)
Location of the Test Piles and Subsurface Information
The test piles location plan and the test set-up/arrangement for lateral test piles are attached in Appendix B.
The relevant site investigation boreholes
information is also attached in Appendix B for ease of reference and the subsoil information from the site investigation are shown in Table 5.7.
Table 5.7:
Summary of Subsoil Information for Site 2 Unit Weight of Soil, γ Friction Angle, φ' Undrained Shear Strength, cu Coefficient of modulus variation, nh
5.3.6
Test Piles Installation
16 kN/m3 35° 0 1250 kN/m3
46
The test piles have a nominal diameter of 600mm with a wall thickness of 100mm and were constructed by a local piling company. The test piles no. TP2a and TP2b were driven to set at 5 meters spacing with the penetration depth of 27.27 meters and 30.27 meters respectively from RL +0.50m MLSD excavated testing platform level. The summary of the piles information are shown in Table 5.8.
Table 5.8:
Summary of Pile Information for 600mm Diameter Spun Piles at
Site 2 TP2a
TP2b
Spun Pile
Spun Pile
600mm
600mm
80 N/mm2
80 N/mm2
Pile Penetration Length from Cut-Off Level
27.77m
30.77m
Free Standing Length
2.50m
2.50m
Total Pile Length
30.27m
33.27m
36000 kN/m2
36000 kN/m2
Moment of Inertia
0.00329 m4
0.00329 m4
Testing Platform Level
RL +0.50m
RL +0.50m
Lateral Load Applied at Level
RL +1.00m
RL +1.00m
Pile Number Pile Type Pile Diameter Grade of Concrete
Modulus of Elasticity
5.3.7
Proposed Instrumentation
In order to obtain the load-deflection along the pile, inclinometer was installed in test pile no. TP2a. The inclinometer tubing was terminated at pile toe, with top of tubing extended to 0.3 meter above top of pile. The location of the inclinometer is indicated in the sketch showing test assembly in Appendix B.
5.3.8
Pile Movement Monitoring System
47
For test pile no. TP2a, the lateral deflection was monitored using a Linear Displacement Transducers (LDT) mounted to a reference frame, with plunger pressing horizontally against a prepared flat vertical surface at the pile side, and an inclinometer using Digitilt Inclinometer Probe which connected to Digitilt Datamate Indicator.
Pile deflection in the pile was measured using the inclinometer at 0.5m intervals at the end of each loading/unloading step. During holding period for each cycle, additional readings were also taken.
On the other hand, for test pile no. TP2b, the lateral deflection was only monitored using a LDT mounted to a reference frame, with plunger pressing horizontally against a prepared flat vertical surface at the pile side as shown in the sketch in Appendix B.
5.3.9
Static Maintained Load Test
For the instrumented test piles, static maintained load tests were carried out and were loaded to yield/failure using test assembly as shown in set-up attached in Appendix B. In the set-up used, the test piles were laterally loaded at the proposed pile cut-off level using a hydraulic jack which was operated by an electric pump. The applied load was indicated by calibrated load cell.
Two cycles load/unloading static maintained load tests were applied to these test piles about two weeks after the piles were installed. At the end of each cycle, the loads were maintained for one hour as per the proposed loading schedule attached in Appendix B before the loads were released. Inclinometer installed in the test pile no. TP2a and LDTs which mounted on an independent support were to monitor the piles lateral movement. In addition the movements of the independent supports were also
48 measured so that any movement of there supports can be corrected for the pile movement.
5.3.10 Test Results
Table 5.9 summarised the results of the two cycles static maintained load tests for 600mm diameter spun piles. The Applied Load – Lateral Deflection plots of measured by both LDT and inclinometer (INCL) were shown in Figure 5.7 and Figure 5.8 for test piles TP2a and TP2b respectively.
During the 2nd Cycle, test pile no. TP2b was cracked at about 3.8 meters from the pile top at loading 247kN.
No transducers and inclinometer reading were
obtained due to the fact that the proposed next reading was at 250kN.
49 Table 5.9:
Summary of the Lateral Deflection for 600mm Diameter Spun Piles at
Site 2 Cycle
First
Second
Applied
Lateral
Lateral
Lateral
Lateral
Deflection for
Deflection for
Deflection for
Load (kN)
TP2a (LDT)
TP2a (INCL)
TP2b (LDT)
(mm)
(mm)
(mm)
0
0.00
0.00
0.00
25
1.03
1.06
1.34
50
2.15
2.74
2.44
75
4.08
4.70
4.40
100
6.20
6.57
6.36
125
8.96
9.50
9.02
100
8.53
8.78
8.64
75
7.56
8.00
7.63
50
6.42
6.38
6.51
25
5.01
5.3
5.11
0
3.50
3.53
3.54
0
3.50
3.53
3.54
25
4.37
4.57
4.53
50
5.51
5.96
5.62
75
6.77
7.17
6.86
100
8.11
8.47
8.15
125
9.84
10.15
9.91
150
12.46
12.73
12.66
175
18.19
18.56
18.22
200
26.40
26.93
26.54
225
37.96
38.95
39.18
0
25.41
21.45
49.89
50
Applied Load vs Lateral Deflection (TP2a) Applied Load, kN 0
50
100
150
200
250
0 5
Lateral Deflection, mm
10 15 20 25 30 35 40 LDT
INCL
45
Figure 5.7:
Plot of Lateral Deflection for TP2a at Site 2 from LDT and
Inclinometer Measurements
Applied Load vs Lateral Deflection (TP2b) Applied Load, kN 0
50
100
150
200
250
0
Lateral Deflection, mm
10
20
30
40
50 LDT
Pile was cracked at about 3.8m from the pile top at loading of 247kN.
60
Figure 5.8:
Plot of Lateral Deflection for TP2b at Site 2 from LDT Measurements
51 5.4
Site 3 – A-380 Hangar/Workshop Facility at MAS Complex in KLIA, Sepang, Selangor
5.4.1
Introduction
For Site 3, the instrumented lateral load test was carried out for the test piles for the construction of a unit of A-380 Hangar/Workshop Facility at MAS Complex in KLIA, Sepang, Selangor. The main objectives of the test are to proof load the test piles to three times the working lateral load and to verify the pile design parameters including the deflection and working capacity of the piles.
5.4.2
Geological Background of the Site
The site is located at the south of Kuala Lumpur and in the coastal plain which underlain by Quaternary deposit. The underlying bedrock is believed to be the Kenny Hill Formation occurring at great depths which is beyond the reach of the investigation boreholes.
Reference to the geological map of the site, the subsurface geology can be characterised by an upper layer of Quaternary deposit, consisting of very soft to soft clayey or sandy silts with lenses of loose silty sand. These sediments were deposited as coastal Alluvium, which had overlain a thick weathered mantle of a metasedimentary rock, widely believed to be the Kenny Hill Formation. Within the Quaternary deposit, a thin layer of desiccated crust is detected, occurring at 1 meter to 2 meters depth below the ground surface (Figure 5.9).
The hard layer as detected by the Standard Penetration Test (SPT) occurs at depths ranging from 8 meters to 18 meters below ground surface. The Kenny Hill Formation consists mainly of interbedded sequences of Phyllite and Quartzite, Shale, Siltstone and Sandstone with isolated lenses of Schist.
DEPTH (m)
52
SOIL TYPE
SPT Nvalue
SPT N - Value (per 30cm) 18 10
20
30
40
50
0
50
Very dense silty SAND (weathered Sandstone fragment) (3.00m)
50
190
9 1
5 Medium stiff to stiff clayey SILT
9-14 9
10
(10.00m)
40 29
Hard to stiff clayey SILT
15
40-22
(15.00m) Very stiff to Hard sandy SILT
23
21-50
21
(18.00m)
200 150
20 200
Hard clayey SILT
150-200
150 150
25
150
(27.15m)
Figure 5.9:
5.4.3
150
Typical Subsoil Profile (Borehole ref. BH-6)
Scope
The scope is to carry out the instrumented static maintained load test for 1050mm diameter cast in-situ bored piles. The main objectives of the instrumented static maintained load test are to proof load the test piles to three times the working lateral load and to establish the response/lateral deflection of the test piles under applied lateral loadings. The load-deflection relationship under loading from measured results will be presented both in tabulated and graphical format for easy assessment.
53 5.4.4
Location of the Test Piles and Subsurface Information
Test piles location plan, installation records and the test set-up/arrangement for lateral test piles are attached in Appendix C. The relevant site investigation boreholes information is also attached in Appendix C for ease of reference and the subsoil information from the site investigation are shown in Table 5.10.
Table 5.10:
Summary of Subsoil Information for Site 3 Unit Weight of Soil, γ
17 kN/m3
Friction Angle, φ'
5.4.5
0
Undrained Shear Strength, cu
65 kN/m2
Coefficient of modulus variation, nh
750 kN/m3
Test Piles Installation
The test piles have a nominal diameter of 1050mm and were constructed by a local bored piling company using mechanical boring machine. For test piles no. TP1 and TP2, the top 12 meters was temporary cased and from 12 meters downwards, the hole was stabilised using bentonite slurry. The test pile no. TP1 and TP2 were bored to a depth of 32.6 meters and 32.8 meters respectively from the ground surface and were concreted by trimie method. The characteristic cube strength of the concrete for these cast in-situ bored piles was 35 N/mm2 with an average slump of 173 mm. The final penetration depth for test pile no. TP1 and TP2 were 30.1 meters and 30.3 meters respectively from RL -2.50m MLSD excavated testing platform level. The summary of the piles information are shown in Table 5.11.
54 Table 5.11:
Summary of Pile Information for 1050mm Diameter Cast In-situ
Bored Piles at Site 3 TP1
TP2
Pile Type
Bored Pile
Bored Pile
Pile Diameter
1050 mm
1050 mm
Grade of Concrete,
35 N/mm2
35 N/mm2
Pile Penetration Length from Cut-Off Level
30.10 m
30.30 m
Free Standing Length
2.50 m
2.50 m
Total Pile Length
32.60 m
32.80 m
27000 kN/m2
27000 kN/m2
Moment of Inertia
0.05967 m4
0.05967 m4
Testing Platform Level
RL -2.50 m
RL -2.50 m
Lateral Load Applied at Level
RL -2.00 m
RL -2.00 m
Pile Number
Modulus of Elasticity
5.4.6
Proposed Instrumentation
In order to obtain the load-deflection along the piles, inclinometer (INCL) was installed in each pile. Inclinometer tubings were terminated at pile toe, with top of tubing extended to 0.3 meter above top of pile. The location of each inclinometer is indicated in the sketch showing test assembly in Appendix C.
5.4.7
Pile Movement Monitoring System
For each pile, the lateral deflection was monitored using:
i) Two numbers of calibrated Linear Strain Displacement Transducers (LSDTs) supported by the reference beam on the compression side of the pile heads using magnetic stands. The plungers were placed on glass squares firmly attached to the piles on a flat vertical plane of each of the
55 piles (compression side) at 2 meters from pile top. LSDTs reading were logged automatically at one minute interval using DataTaker DT50 datalogger.
ii) The full lateral deflection profile of the pile was measured with the aid of an inclinometer using Digitilt Inclinometer Probe and Digitilt Datamate Indicator.
Pile deflections in the piles were measured using the inclinometer at 0.5m intervals at the end of each loading/unloading step. During holding period for each cycle, additional readings were also taken.
5.4.8
Static Maintained Load Test
For the instrumented test piles, static maintained load tests were carried out and were loaded to three times of its proposed design working load using test assembly as shown in set-up attached in Appendix C. In the set-up used, the test piles were laterally loaded at the proposed pile cut-off level using one number of 200 tonne hydraulic jack which was operated by an electric pump. The hydraulic jack was laid inline at 2 meters from pile top. The applied load was indicated by one number of 250 tonne calibrated load cell.
Pressure gauge readings were also
recorded as back-up counter checking purpose. Three cycles load/unloading static maintained load tests were applied to these test piles about one month after the piles were installed. At the end of each cycle, the loads were maintained for six hours for the first two cycles and 1 hour for the final cycle as per loading schedule attached in Appendix C before the loads were released. LSDTs which supported on an independent beams and inclinometers were used to monitor the piles lateral movement. All of these instruments were connected to a data acquisition system for real-time data viewing. In addition the movements of the independent supports were also measured so that any movement of there supports can be corrected for the pile movement.
56 5.4.9
Test Results
Table 5.12 summarised the results of the three cycles static maintained load tests for 1050mm diameter cast in-situ bored piles. The Applied Load – Lateral Deflection plots of measured by both LSDTs and inclinometer (INCL) were shown in Figure 5.10 and Figure 5.11 for test piles TP1 and TP2 respectively.
57 Table 5.12:
Summary of the Lateral Deflection for 1050mm Diameter Cast In-situ
Bored Piles at Site 3 Cycle
Applied
Average
Lateral
Average
Lateral
Lateral
Lateral
Deflection
Lateral
Deflection
Load (kN)
Deflection
for TP1
Deflection
for TP2
for TP1
(INCL)
for TP2
(INCL)
(LSDTs)
(mm)
(LSDTs)
(mm)
(mm)
First
(mm)
0
0.0
0.0
0.0
0.0
30
0.2
0.5
0.2
0.3
60
0.5
1.0
0.4
0.3
90
0.8
1.4
0.7
1.3
120
1.0
1.5
1.0
2.4
150
1.4
1.6
1.4
2.9
180
1.8
2.1
1.8
3.1
210
2.5
3.0
2.5
5.4
240
3.1
3.1
3.1
7.3
270
3.9
4.2
3.8
7.8
300
5.0
5.4
4.8
9.2
225
4.8
5.0
4.6
6.6
150
3.8
4.0
3.8
5.7
75
3.3
3.4
3.4
4.5
0
2.0
2.0
1.9
4.5
58
Cycle
Applied
Average
Lateral
Average
Lateral
Lateral
Lateral
Deflection
Lateral
Deflection
Load (kN)
Deflection
for TP1
Deflection
for TP2
for TP1
(INCL)
for TP2
(INCL)
(LSDTs)
(mm)
(LSDTs)
(mm)
(mm)
Second
(mm)
0
2.0
2.0
1.9
4.5
75
2.5
3.9
2.3
5.8
150
3.3
4.4
3.1
6.2
225
4.1
4.5
3.9
7.4
300
4.9
5.1
4.7
9.3
330
5.4
5.3
5.2
9.6
360
6.2
6.5
5.7
10.2
390
7.0
7.1
6.4
10.9
420
7.7
7.6
7.0
11.1
450
8.5
7.6
7.6
13.4
480
9.4
7.8
8.3
13.8
510
10.8
8.9
9.1
14.6
540
11.9
9.4
9.9
15.3
570
12.9
10.2
10.6
16.8
600
15.4
12.6
12.1
17.7
450
14.9
12.2
11.5
17.7
300
13.7
12.0
10.5
16.1
150
11.3
10.1
8.6
13.6
0
6.0
5.0
4.1
9.7
59
Cycle
Applied
Average
Lateral
Average
Lateral
Lateral
Lateral
Deflection
Lateral
Deflection
Load (kN)
Deflection
for TP1
Deflection
for TP2
for TP1
(INCL)
for TP2
(INCL)
(LSDTs)
(mm)
(LSDTs)
(mm)
(mm)
Third
(mm)
0
6.0
5.0
4.1
9.7
150
7.9
6.6
5.6
12.4
300
10.4
9.2
7.6
14.2
450
12.7
11.1
9.8
17.5
600
15.6
13.2
12.3
18.1
630
16.4
14.2
13.0
21.6
660
17.4
15.9
13.8
21.9
690
18.8
16.1
14.9
22.3
720
20.4
17.8
16.2
23.1
750
21.8
20.4
17.3
24.4
780
23.6
20.7
18.8
27.9
810
24.9
22.3
20.3
28.0
840
26.0
23.3
21.3
28.1
870
27.4
24.1
23.1
28.7
900
29.9
25.3
25.2
34.3
600
28.2
25.2
23.5
30.4
450
26.4
22.5
21.9
29.8
300
23.9
21.7
19.6
28.3
150
19.7
16.1
15.9
23.8
0
10.4
7.8
7.4
14.4
60
Applied Load vs Lateral Deflection (TP1) Applied Load, kN 0
100
200
LSDTs
INCL
300
400
500
600
700
800
900
1000
0
5
Lateral Deflection, mm
10
15
20
25
30
35
Figure 5.10: Plot of Lateral Deflection for TP1 at Site 3 from LSDTs and
Inclinometer Measurements
Applied Load vs Lateral Deflection (TP2) Applied Load, kN 0
100
200
300
400
500
600
700
800
900
0 5
Lateral Deflection, mm
10 15 20 25 30 35 LSDTs
INCL
40
Figure 5.11: Plot of Lateral Deflection for TP2 at Site 3 from LSDTs and
Inclinometer Measurements
1000
CHAPTER 6
DATA ANALYSIS
6.1
Introduction
Data analysis is the most essential section of this thesis, which has a function to obtain results that will govern the success of the thesis. To carry out the analysis, a well planned method and type of applications or equations to be utilised must be clearly established. For example, the reason to utilise a certain equation must be validated.
In this thesis, there are two methods of analysis were selected to obtain the results that finally assisted in achieving the intended comparisons. The first analysis is to calculate the lateral deflection of the pile utilising method of Broms as established in his papers published in 1964 and Characteristic Load Method (CLM) presented by Duncan, Evans & Ooi (1994). The second analysis is to compare the calculated lateral deflection with measured values based on pile installation methods and types of soil.
The above mentioned analyses have been carried out and formulated in Microsoft Excel Spreadsheets to simplify the intended calculation process.
All
spreadsheets had been verified by providing detail breakdowns for each spreadsheet formulation for both design methods.
62 6.2
Ground-Line Deflection Formulations
Spreadsheet shown in Figure 6.1a & 6.1b and Figure 6.2a & 6.2b are for the calculation of ground-line deflection for both Broms and CLM formulations respectively.
The verification of the spreadsheets is discussed in the following sections and the sample calculations are cross-referred to the ground-line deflection calculation from Site 1 for 1050mm diameter cast in-situ bored piles in cohesionless soil.
The following parameters were obtained from the test piles and site investigation results:
Pile Number
TP2
Pile Diameter, D
1050 mm
Grade of Concrete, fcu
40 N/mm2
Pile Penetration Length from Cut-Off Level to Pile Toe
45.95 m
Pile Length from Cut-Off Level to Platform Level, e
0.50 m
Total Pile Length from Cut-Off Level to Pile Toe, L
46.45 m
Modulus of Elasticity, Ep
28000 MN/m2
Moment of Inertia, Ip
0.05967 m4
Unit Weight of Soil, γ
18 kN/m3
Friction Angle, φ' Undrained Shear Strength, cu
35° 0
Coefficient of modulus variation, nh
1250 kN/m3
Testing Platform Level
RL +1.45 m
Lateral Load Applied at Cut-Off Level
RL +1.95 m
Applied Lateral Load Applied Moment
190 kN 0
63 6.2.1
Broms’ Ground-Line Deflection Formulation
Figure 6.1a: Spreadsheet of Broms’ Ground-Line Deflection Formulation (Part 1
of 2)
64
Figure 6.1b: Spreadsheet of Broms’ Ground-Line Deflection Formulation (Part 2
of 2)
Verification of spreadsheet for Broms’ ground-line deflection formulation and it is read in conjunction with Figure 6.1a and Figure 6.1b:
Broms’ Ground-Line Deflection Equation: y=
2.4 H (1 + 0.67eη )
(
nh 3 5 E p I p
)2 5
(From Equation 2.1)
where
η =5
nh EpI p
(From Equation 2.2)
65 Calculation for η,
η=
5
(2.8 × 10
1250kN / m 3 7
)(
kN / m 2 0.05967 m 4
)
η = 0.237m −1
Therefore, y=
[
(
2.4(190kN ) 1 + 0.67(0.5m ) 0.237 m −1
(1250kN / m ) [(2.8 × 10 3 35
y = 0.0221m. Verified
7
)(
)]
kN / m 2 0.05967m 4
)]
25
66 6.2.2
CLM’s Ground-Line Deflection Formulation
Figure 6.2a: Spreadsheet of CLM’s Ground-Line Deflection Formulation (Part 1 of
2)
67
Figure 6.2b: Spreadsheet of CLM’s Ground-Line Deflection Formulation (Part 2 of
2)
Verification of spreadsheet for CLM’s ground-line deflection formulation and it is read in conjunction with Figure 6.2a and Figure 6.2b:
CLM’s Ground-Line Deflection Equation: y comb =
y tpm + y tmp 2
(From Equation 2.15)
68 Step 1: Calculate the Characteristic Load and Characteristic Moment ⎛ σp ⎞ ⎟ Pc = λ1 D E p R1 ⎜ ⎜ E p R1 ⎟ ⎝ ⎠
m1
2
⎛ σp ⎞ ⎟ M c = λ2 D E p R1 ⎜ ⎜ E p R1 ⎟ ⎝ ⎠
(ε 50 )r1
m2
3
(From Equation 2.7)
(ε 50 )r2
(From Equation 2.8)
Calculate moment of inertia ratio, R1: R1 =
Ip I circular
I circular =
πD 4 64
(From Equation 2.9) = 0.05967m 4
Thus, R1 =
0.05967m 4 0.05967m 4
=1
Calculate passive pressure of the soil, σp: ⎛ ⎝
σ p = 2C pφ γD tan 2 ⎜ 45° +
φ′⎞ ⎟ 2⎠
(From Equation 2.11)
where
C pφ = C pφ =
φ′ 10
(From Equation 2.12)
35° = 3.5 10
Hence,
(
)
⎛ ⎝
σ p = 2(3.5)(1.05m ) 18kN / m 3 − 9.81kN / m 3 tan 2 ⎜ 45° + σ p = 222.14kN / m 2
35° ⎞ ⎟ 2 ⎠
69 Calculate characteristic load, Pc: ⎛ σp ⎞ ⎟ Pc = λ1 D E p R1 ⎜ ⎜ E p R1 ⎟ ⎝ ⎠
m1
2
(ε 50 )n1
where λ1 = 1.00, ε50 from Table 2.2 is 0.002, m1 and r1 from Table 2.3 is 0.57 and 0.22 respectively.
So, Pc = (1)(1.05m )
(
)
⎛ 222.14kN / m 2 ⎞ ⎟ 2.8 × 10 kN / m (1)⎜⎜ 7 2 ⎟ ⎝ 2.8 × 10 kN / m (1) ⎠
2
7
2
(
0.57
)
(0.002)−0.22
Pc = 149969.23kN
Calculate characteristic moment, Mc: ⎛ σp ⎞ ⎟ M c = λ2 D 3 E p R1 ⎜ ⎜ E p R1 ⎟ ⎝ ⎠
m2
(ε 50 )n2
where λ2 = 1.00, ε50 from Table 2.2 is 0.002, m2 and r2 from Table 2.3 is 0.40 and 0.15 respectively.
Therefore, M c = (1)(1.05m )
3
(
)
⎛ 222.14kN / m 2 ⎞ ⎟ 2.8 × 10 kN / m (1)⎜⎜ 7 2 ⎟ ( ) 2 . 8 10 / 1 × kN m ⎝ ⎠ 7
2
(
)
0.40
(0.002)−0.15
M c = 750508.08kNm
Step 2: Check the Minimum Pile Length E p R1
γDφ ′K p
(2.8 × 10 kN / m )(1) = (8.19kN / m )(1.05m)(35°)⎡⎢tan ⎛⎜ 45° + 352° ⎞⎟⎤⎥ 7
2
3
2
⎣
E p R1
γDφ ′K p
⎝
⎠⎦
= 25209.84
From Table 2.6, minimum pile length = 11D = 11(1.05m) = 11.55m < 46.45 m. OK
70 Step 3: Calculate the Ground-Line Deflections due to the Applied Load and the Moment Calculate ground-line deflection due to the applied load, ytp: ⎛P y tp = a1 ⎜⎜ t ⎝ Pc
b
⎞1 ⎟⎟ D ⎠
(From Equation 2.13)
where a1 = 119 and b1 = 1.523 from Table 2.4 Thus, ⎛ 190kN ⎞ y tp = 119⎜ ⎟ ⎝ 149969.23kN ⎠
1.523
(1.05m )
y tp = 0.00483m
Calculate ground-line deflection due to the moment, ytm: y tm
⎛M = a 2 ⎜⎜ t ⎝ Mc
b2
⎞ ⎟⎟ D ⎠
(From Equation 2.14)
where a2 = 36 and b2 = 1.308 from Table 2.4 Hence, y tm
0 ⎛ ⎞ = 36⎜ ⎟ ⎝ 750508.08kNm ⎠
1.308
(1.05m )
y tm = 0
Step 4: Calculate the Equivalent Load Pm and the Equivalent Moment Mp Calculate the equivalent load caused by the real moment, Pm: ⎛P y tm = a1 ⎜⎜ m D ⎝ Pc
⎞ ⎟⎟ ⎠
b1
(From Equation 2.13)
Therefore, ⎡ y tm ⎢b 1 Pm = Pc ⎢ D ⎢ a1 ⎢ ⎣
⎤ ⎡ 0 ⎤ ⎥ ⎥ ⎢1.523 1.05m ⎥ = 0 ⎥ = (149969.23kN )⎢ 119 ⎥ ⎥ ⎢ ⎥ ⎥⎦ ⎢⎣ ⎦
71 Calculate the equivalent moment caused by the real load, Mp: ⎛Mp = a 2 ⎜⎜ D ⎝ Mc
y tp
⎞ ⎟ ⎟ ⎠
b2
(From Equation 2.14)
So, ⎡ ⎛ 0.00483m ⎞ ⎤ ⎜ ⎟⎥ ⎢ D = (750508.08kNm )⎢1.308 ⎝ 1.05m ⎠ ⎥ ⎢ ⎥ a2 36 ⎢ ⎥ ⎢⎣ ⎥⎦
y tp M p = Mc
b2
M p = 792.23kNm
Step 5: Calculate the Ground-Line Deflections due to the applied load plus equivalent load (Pt + Pm) and the moment plus equivalent moment (Mt + Mp) Calculate the Ground-Line Deflections due to the applied load plus equivalent load (Pt + Pm), ytpm: b
y tpm
⎛ P + Pm = a1 ⎜⎜ t ⎝ Pc
⎞1 ⎟⎟ D ⎠
y tpm
⎛ 190kN + 0 ⎞ = 119⎜ ⎟ ⎝ 149969.23kN ⎠
(From Equation 2.13) 1.523
(1.05m )
ytpm = 0.00483m
Calculate the Ground-Line Deflections due to the moment plus equivalent moment (Mt + Mp), ytmp: b2
y tmp
⎛ Mt + M p = a 2 ⎜⎜ ⎝ Mc
y tmp
⎛ 0 + 792.23kNm ⎞ = 36⎜ ⎟ ⎝ 750508.08kNm ⎠
y tmp = 0.00483m
⎞ ⎟ D ⎟ ⎠
(From Equation 2.14) 1.308
(1.05m )
72 Step 6: Calculate the Average Ground-Line Deflections, ycomb y comb = y comb =
y tpm + y tmp 2
(From Equation 2.15)
0.00483m + 0.00483m 2
ycomb = 0.00483m.
Verified.
CHAPTER 7
RESULTS AND DISCUSSIONS
7.1
Introduction
Based on the data obtained from the selected sites, the values of the lateral deflection have been calculated based on Broms’ method and CLM with reference to the types of soil and types of pile. From the calculated results and measured values, the following comparison have been carried out for: 1) driven piles and cast in-situ bored piles in cohesionless soil; and 2) cast in-situ bored piles in cohesionless and cohesive soils.
7.2
Results of Analyses for Ground-Line Deflection
The results for the ground-line deflection from both Broms’ and CLM’s formulations with reference to types of soil and pile installation methods have been calculated and tabulated together with measured deflection in Table 7.1, Table 7.2 and Table 7.3.
74 Table 7.1:
Summary of the Lateral Deflection for 600mm Diameter Spun Piles in
Cohesionless Soil Applied Load
Lateral Deflection (mm)
(kN)
Broms Method
CLM
Measured
0
0.0
0.0
0.0
60
17.4
4.2
4.3
60
17.4
4.2
4.2
75
22.0
7.5
7.2
125
36.6
16.3
9.5
135
39.1
14.4
17.1
135
39.1
14.4
14.0
150
43.5
16.9
21.8
150
43.5
16.9
18.8
175
50.7
21.3
27.2
175
50.7
21.3
26.0
200
58.6
33.3
26.9
225
65.9
39.9
39.0
75 Table 7.2:
Summary of the Lateral Deflection for 1050mm Diameter Cast In-situ
Bored Piles in Cohesionless Soil Applied Load
Lateral Deflection (mm)
(kN)
Broms Method
CLM
Measured
0
0.0
0.0
0.0
100
11.6
1.8
2.5
100
11.6
1.8
1.5
190
22.1
4.8
4.5
190
22.1
4.8
4.0
350
40.8
12.3
12.4
350
40.8
12.3
14.1
475
55.3
19.5
21.6
475
55.3
19.5
15.8
600
69.9
27.8
29.6
600
69.9
27.8
23.7
750
87.3
39.1
38.5
750
87.3
39.1
30.9
76 Table 7.3:
Summary of the Lateral Deflection for 1050mm Diameter Cast In-situ
Bored Piles in Cohesive Soil Applied Load
7.3
Lateral Deflection (mm)
(kN)
Broms Method
CLM
Measured
0
0.0
0.0
0.0
150
11.8
2.3
1.9
150
11.8
2.3
3.4
300
23.6
8.1
5.4
300
23.6
8.1
10.4
450
35.4
17.0
8.8
450
35.4
17.0
14.9
600
47.1
28.7
14.6
600
47.1
28.7
20.0
750
58.9
43.2
23.5
750
58.9
43.2
27.7
900
70.7
60.2
29.1
900
70.7
60.2
38.8
Comparison with Pile Installation Methods in Cohesionless Soil
Total three pairs of test piles were installed in cohesionless soil using driven method and cast in-situ method. One pair of 1050mm diameter cast in-situ test piles was installed at Site 1, Jimah and two pair of 600mm diameter driven test piles were installed each in Site 1, Jimah and Site 2, Tanjung Bin respectively. Based on pile installation methods, the measured lateral deflection from the instrumented test piles and calculated lateral deflection are shown in Figure 7.1 and Figure 7.2. Due to limitation of instrumented field test results, piles install in cohesive soil will not be discussed.
77
Applied Load - Lateral Deflection Curves Lateral Deflection, mm 0
50
100
150
200
250
0.0
10.0
Applied Load, kN
20.0
30.0 R2 = 0.9616 40.0 R2 = 0.972 50.0
Poly. (Broms Method - 600mm Dia. Spun Pile (Sand))
60.0
Poly. (CLM - 600mm Dia. Spun Pile (Sand)) Poly. (Measured - 600mm Dia. Spun Pile (Sand)) 70.0
R2 = 0.9999
Figure 7.1:
Comparison of Measured and Calculated Lateral Defections for
Driven Piles
Applied Load - Lateral Deflection Curves Lateral Deflection, mm 0
100
200
300
400
500
600
700
800
0.0
10.0
20.0 R2 = 0.9609
Applied Load, kN
30.0
40.0 R2 = 0.9993 50.0
60.0
70.0
80.0 Poly. (Broms Method - 1050mm Dia. Bored Pile (Sand)) Poly. (CLM - 1050mm Dia. Bored Pile (Sand))
90.0
Poly. (Measured - 1050mm Dia. Bored Pile (Sand))
R2 = 1
100.0
Figure 7.2:
Comparison of Measured and Calculated Lateral Defections for Cast
In-situ Bored Piles
78 It can be seen that for 600mm diameter driven spun piles the calculated values of lateral deflection based on Broms’ method are 59% larger than those measured. The values calculated using CLM are 4% smaller than the measured values and this could be due to the fact that the pile joint was located at the point of the fixity of the pile which resulted larger deflection of the pile installed.
However, 1050mm diameter cast in-situ bored piles gave the calculated values of 2% higher than the measured values using CLM. The measured deflections are 64% smaller than the calculated values from Broms’ method.
The calculated values from CLM for cast in-situ bored agree very well with the measured value compared to Broms’ method.
7.4
Comparison with Types of Soil for Cast In-situ Bored Piles
Total of one pair of 1050mm diameter cast in-situ test piles were installed in cohesionless soil at Site 1, Jimah and in stiff cohesive soil at Site 3, KLIA respectively. Due to limitation of instrumented field test results, driven pile in cohesionless soil will not be discussed in this thesis. The calculated lateral deflection using Broms’ method and CLM are compared to those measured from the instrumented test piles are shown in Figure 7.3 and Figure 7.4.
Based on Broms’ method, the calculated lateral deflection for 1050mm diameter cast in-situ bored piles are 70% and 64% higher than the measured values for cohesionless and cohesive soils respectively. Aside from Broms’ method, the values calculated using CLM are 2% and 24% larger than the measured values for cohesionless and cohesive soils respectively.
It shows that the calculated deflections from CLM agree quite well with the measured value for cohesionless soil compared to method of Broms.
79
Applied Load - Lateral Deflection Curves Lateral Deflection, mm 0
100
200
300
400
500
600
700
800
0.0
10.0
20.0 R2 = 0.9609
Applied Load, kN
30.0
40.0 R2 = 0.9993 50.0
60.0
70.0
80.0 Poly. (Broms Method - 1050mm Dia. Bored Pile (Sand)) Poly. (CLM - 1050mm Dia. Bored Pile (Sand))
90.0
R2 = 1
Poly. (Measured - 1050mm Dia. Bored Pile (Sand)) 100.0
Figure 7.3:
Comparison of Measured and Calculated Lateral Defections for Cast
In-situ Bored Piles in Cohesionless soil
Applied Load - Lateral Deflection Curves Lateral Deflection, mm 0
100
200
300
400
500
600
700
800
900
1000
0.0
10.0
20.0
Applied Load, kN
R2 = 0.9376 30.0
40.0
50.0
60.0 R2 = 0.9999
Poly. (Broms Method - 1050mm Dia. Bored Pile (Clay)) 70.0
Poly. (CLM - 1050mm Dia. Bored Pile (Clay)) Poly. (Measured - 1050mm Dia. Bored Pile (Clay))
R2 = 1
80.0
Figure 7.4:
Comparison of Measured and Calculated Lateral Defections for Cast
In-situ Bored Piles in Cohesive soil
80 7.5
Investigation of the Case for Spun Piles Installed in Cohesionless Soil
Total two pairs of 600mm diameter spun piles were installed in cohesionless soil each in Site 1, Jimah and Site 2, Tanjung Bin respectively. To investigate the causes of resulting smaller values of calculated lateral deflection when compared to measured values, the results of lateral deflection for the two sites were tabulated and plotted individually and are shown in Table 7.4, Table 7.5, Figure 7.5 and Figure 7.6 respectively.
Table 7.4:
Summary of the Lateral Deflection for 600mm Diameter Spun Piles in
Cohesionless Soil at Site 1, Jimah, Negeri Sembilan Applied Load
Table 7.5:
Lateral Deflection (mm)
(kN)
Broms Method
CLM
Measured
0
0.0
0.0
0.0
60
17.4
4.2
4.3
60
17.4
4.2
4.2
135
39.1
14.4
17.1
135
39.1
14.4
14.0
150
43.5
16.9
21.8
150
43.5
16.9
18.8
175
50.7
21.3
27.2
175
50.7
21.3
26.0
Summary of the Lateral Deflection for 600mm Diameter Spun Piles in
Cohesionless Soil at Site 2, Tanjung Bin, Johor Applied Load
Lateral Deflection (mm)
(kN)
Broms Method
CLM
Measured
0
0.0
0.0
0.0
75
22.0
7.5
7.2
125
36.6
16.3
9.5
200
58.6
33.3
26.9
225
65.9
39.9
39.0
81
Applied Load - Lateral Deflection Curves Lateral Deflection, mm 0
20
40
60
80
100
120
140
160
180
200
0.0
10.0
R2 = 0.9997
Applied Load, kN
20.0
30.0
R2 = 0.9848
40.0
50.0
Poly. (Broms Method - 600mm Dia. Spun Pile (Sand)) Poly. (CLM - 600mm Dia. Spun Pile (Sand))
R2 = 1
Poly. (Measured - 600mm Dia. Spun Pile (Sand)) 60.0
Figure 7.5:
Comparison of Measured and Calculated Lateral Defections for
600mm Diameter Spun Piles in Site 1, Jimah, Negeri Sembilan
Applied Load - Lateral Deflection Curves Lateral Deflection, mm 0
50
100
150
200
250
0.0
10.0
Applied Load, kN
20.0
30.0 R2 = 0.9783 40.0 R2 = 0.9998 50.0
60.0
Poly. (Broms Method - 600mm Dia. Spun Pile (Sand)) Poly. (CLM - 600mm Dia. Spun Pile (Sand))
R2 = 1
Poly. (Measured - 600mm Dia. Spun Pile (Sand)) 70.0
Figure 7.6:
Comparison of Measured and Calculated Lateral Defections for
600mm Diameter Spun Piles in Site 2, Tanjung Bin, Johor
82 For Site 1, the calculated lateral deflections based on method of Broms are 59% larger than the measured values and the values calculated using CLM are 14% smaller than the measured values. As for Site 2, the calculated values of lateral deflection using Broms’ method are 59% larger than the measured value and the values calculated using CLM are 17% higher than measured lateral deflections.
From the above results and pile installation records for the two test sites, it can be seen that larger measured values of lateral deflection obtained from Site 1 could be due to the pile joint was located at the point of the fixity of the pile which resulted larger deflection of the pile installed. As for Site 2, the calculated values compared to the measured values are having similar trend with other test piles regardless the types of soil the test piles were installed or the installation methods of the test piles.
Therefore, it can be concluded that the smaller calculated lateral deflection when compared to the measured values using CLM given in Section 7.3 of comparison with pile installation methods in cohesionless soil are mainly contributed and resulted from Site 1 which is due to the point of the pile fixity collided with the pile joint of the pile installed.
Apart from the CLM, it was noted that the calculated lateral deflections obtained using method of Broms have not affect and are not influence to the pile joint.
In overall, the calculated deflections from CLM agree quite well with the measured value compared to Broms’ method.
83 7.6
Discussion
Based on the graphs obtained, Broms’ method developed linear type of trend lines. This could be due to that in Broms’ method, the load-deflection relationship is similar to the stress-strain relationship as obtained from consolidation-undrained test. At load less than one-half to one-third the ultimate lateral resistance of the pile, the deflection increase approximately linear with the applied load.
As for CLM, it developed polynomial or nonlinear type of trend lines. This could be due to that in CLM, the load-deflection behaviour of the soil around the pile is nonlinear. As the load transferred from the pile to the soil increases by a fraction of its value, the deflection increses by a greater fraction. Even though the behaviour of the pile itself may continue to be linear, the behaviour of the pile/soil system is nonlinear.
7.7
Summary of Results and Discussion
From the analyses, it is found that method of Broms provides a more conservative lateral deflection value compared to CLM for both cohesionless and cohesive soils; and, both driven and cast in-situ bored piles.
The discrepancy
between measured and calculated values using CLM for driven piles in cohesionless soil apart from the point of the pile fixity collided with the pile joint can be attributed at least partly to the increase in relative density of the soil which takes place during driving of the piles.
CLM gave a larger deflection for cohesive soil than cohesionless soil. It is agreed with the statement made by Duncan, Evans and Ooi’s that CLM estimates slightly larger deflections for deep foundations in stiff cohesion soil.
84 Generally, for simple analysis method, various simplifications have been necessary in order to provide simple solutions to complex problems of soil-structure interaction and the limitations of the methods. These have manipulated the accuracy of the results when compared with measured values.
The trend line was plotted in a manner where the line interests the most number of points making it a best fit line. From the graphs obtained, the limit of R2 is around 0.94 to 1, and this is deemed consistent and acceptable for analysis purposes. If more test data from sites were available, the accuracy of the results may be further enhanced.
CHAPTER 8
CONCLUSIONS AND RECOMMENDATIONS
8.1
Conclusions
From the calculated lateral deflections and data collected from various sites obtained for this thesis, the following conclusion can be distinguished:
a) Method of Broms provides a more conservative lateral deflection value when compared to CLM for both cohesionless and cohesive soils. The graphs developed using Broms’ method are of linear type. For CLM, on the other hand, the graphs developed are of polynomial type.
b) For static load conditions, the CLM closely approximates the results of measured deflections for cast in-situ bored piles in cohesionless soil, and estimates slightly larger deflections than measured for cast in-situ bored piles in stiff cohesion soil. On the other hand, for driven piles, CLM gives a slightly higher deflection than measured values in cohesionless soil. This could be due to the fact that the pile joint was located at the point of the fixity of the pile which resulted larger deflection of the pile installed.
c) Comparisons with results of static maintained load tests on single, elastic and free-head cast in-situ bored piles for CLM in cohesionless and cohesive soils show that the results of these analyses are in reasonable agreement with measured field behaviour. The accuracy of CLM depends on the information
86 on soil conditions and its properties, and it provides a simple, practical basis for design of laterally loaded deep foundation.
The available test data are, however, limited and the proposed methods should be applied with caution.
8.2
Recommendations
The following recommendations shall be considered to further enhance the results of this thesis:
i)
More sites should be studies in Malaysia, as the data collected for this thesis may not be sufficient due to the time frame allocated to carry out for this thesis. More data from various sites across Malaysia will enhance the accuracy of the results obtained.
ii)
The laboratory test carried out for the soil sample has to be done professionally and with care to ensure that the soil parameters obtained are accurate and can be relied upon.
iii)
The pile installation carried out at various site must be controlled and monitored closely to ensure the test pile produced has similar properties of the piles proposed for production.
iv)
The instrumented static maintained load test should be monitored closely and all instruments used should be calibrated to ensure the reliability of the measurement results.
87
REFERENCES
Anderson, J.B., Townsend, F.C., and Grajales, B. (2003). “Case History Evaluation of Laterally Loaded Piles”, J. Geotech. and Geoenvir. Engrg., Volume 129, Issue 3, pp. 187-196. Brettmann, T. and Duncan, J.M. (1996). “Computer application of CLM Lateral Load analysis to Piles and drilled shafts”.
Journal of Geotechnical
Engineering, American Society of Civil Engineers, Vol. 120, Issue 6, pp. 496-497. Broms, B. (1964a). “The lateral resistance of piles in cohesionless soils”, Journal of the Soil Mechanics Division, American Society of Civil Engineers, Vol. 90, No. SM3, pp. 123-56. Broms, B. (1964b). “The lateral resistance of piles in cohesive soils”, Journal of the Soil Mechanics Division, American Society of Civil Engineers, Vol. 90, No. SM2, pp. 27-63. Duncan, J.M., Evans Jr., L.T., and Ooi, P.S.K. (1994). “Lateral Load Analysis of Single Piles and Drilled Shafts”, Journal of Geotechnical Engineering, Volume 120, Issue 5, pp. 1018-1033. Evans, L.T.Jr. and Duncan, J.M. (1982). Simplified analysis of laterally loaded piles. Report No. UCB/GT/82-04, University of California, Berkeley, California. Grarssino, A., Jamiolkowski, M. and Pasqualine, E. (1976). “Soil modulus for laterally-load piles in sands and NC clays”, Proceedings of the 6th European Conference, ISSMFE, Vienna. Vol. 1 (2), pp. 429-434. Hsiung, Y.M. (2003). “Theoretical Elastic-Plastic Solution for Laterally Loaded Piles, J. Geotech. and Geoenvir. Engrg., Volume 129, Issue 6, pp. 475-480. Matlock, H. (1970). “Correlation of design of laterally loaded piles in soft clays”. Proceedings of the 2nd Offshore Technology Conference, Dallas, Texas, pp. 577-594.
88 Poulos, H.G. and Davis, E.H. (1980). Pile Foundation Analysis and Design, John Wiley and Sons, New York. Reese, L.C. (1984). Handbook on Design of Piles and Drilled Shafts under Lateral Load, Report No. FHWA-IP-84-11, Geotechnical Engineering Center, The University of Texas, Austin, Texas. Sadek, S. and Freiha, F. (2005). “The use of spreadsheets for the seismic design of piles”, eJSiE 1(3), Bond University, pp. 164-189. Terzaghi, K. (1955).
“Evaluation of coefficients of subgrade reaction”,
Geotechnique, Vo. 5, No. 4, pp. 297-326. Tomlinson, M.J. (2001). Pile Design and Construction Practice, 4th Ed., E & FN Spon, London. Walkenbach, J. (2004). Microsoft Office Excel 2003 Power Programming with VBA, Wiley Publishing, Inc., Indianapolis, Indiana. Welch, R.C. and Reese, L.C. (1972). Lateral Load Behavior of Drilled Shafts, Research Report No. 3-5-65-89, Center for Highway Research, The University of Texas, Austin, Texas.
89
APPENDIX A Test Piles Details for 1050mm Diameter Cast In-situ Bored Piles (TP1 and TP2) and 600mm Diameter Spun Piles (TP3c and TP4)
90
Figure A.1:
Location Plan for the Test Piles No. TP1, TP2, TP3c and TP4
91
A.1
1050mm Diameter Cast In-Situ
Bored Piles
92 Test Pile Installation Record for TP1 (1050mm Diameter Cast In-Situ Bored Pile)
93
94 Test Pile Installation Record for TP2 (1050mm Diameter Cast In-Situ Bored Pile)
95
96
97 Site Investigation Records for ABH 8 and 6
98
99
100
101 Static Maintained Load Test Set-up/Arrangement Plan for Test Pile No. TP1 and TP2
Figure A.2:
Set-Up/Arrangement and Instrumentation Plan for TP1 and TP2
102
Figure A.3:
TP2
Plan View on Set-Up/Arrangement and Instrumentation for TP1 and
103
104
A.2
600mm Diameter Spun Piles
105 Test Pile Installation Record for TP3c (600mm Diameter Spun Pile)
106 Test Pile Installation Record for TP4 (600mm Diameter Spun Pile)
107 Site Investigation Records for ABH 28
108
109 Static Maintained Load Test Set-up/Arrangement Plan for Test Pile No. TP3c and TP4
Figure A.4:
Set-Up/Arrangement and Instrumentation Plan for TP3c and TP4
110
111
APPENDIX B Test Piles Details for 600mm Diameter Spun Piles (TP2a and TP2b)
112
Figure B.1:
Location Plan for the Test Piles No. TP2a and TP2b
113 Site Investigation Records for BBH-1
114
115
116
117
118
119 Static Maintained Load Test Set-up/Arrangement Plan for Test Pile No. TP2a and TP2b
Figure B.2:
Set-Up/Arrangement and Instrumentation Plan for TP2a and TP2b
120 Static Maintained Load Test Set-up/Arrangement Plan for Test Pile No. TP2a and TP2b
Figure B.3:
Set-Up/Arrangement and Instrumentation Plan for TP2a and TP2b
121
APPENDIX C Test Piles Details for 1050mm Diameter Cast In-situ Bored Piles (TP1 and TP2)
122
Figure C.1:
Location Plan for the Test Piles No. TP1 and TP2
123 Test Pile Installation Record for TP1 (1050mm Diameter Cast In-Situ Bored Pile)
124 Test Pile Installation Record for TP2 (1050mm Diameter Cast In-Situ Bored Pile)
125 Site Investigation Records for BH-18
126
127
128 Static Maintained Load Test Set-up/Arrangement Plan for Test Pile No. TP1 and TP2
Figure C.2:
Set-Up/Arrangement and Instrumentation Plan for TP1 and TP2
129
