User Manual for PileLAT (Version 2.3)

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User Manual for PileLAT (Version 2.3)

By Innovative Geotechnics Pty Ltd

2021/8/13

User Manual for PileLAT (Version 2.3) A Program for Single Piles under Lateral Loading

By Innovative Geotechnics Pty Ltd

2021/8/13

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Important Warning:

Please carefully read the following warning and disclaimers before downloading or using the software and its accompanied user manual. Although this software has been developed by Innovative Geotechnics Pty Ltd with considerable care and the accuracy of this software has been checked and verified with many tests and validations, this software shall not be used for design unless the analysis results from this software can be verified by field testing and independent analyses and design from other parties. The users are responsible for checking and verifying the results and shall have thorough and professional understanding about the geotechnical engineering principles and relevant design standards. In no event shall Innovative Geotechnics Pty Ltd and any member of the organization be responsible or liable for any consequence and damages (including, without limitation, lost profits, business interruption, lost information, personal injury, loss of privacy, disclosure of confidential information) rising from using this software.

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TABLE OF CONTENTS

Chapter 1. Introduction ..................................................................................................................................................... 5

Chapter 2. Start the new file .............................................................................................................................................. 7

Chapter 3. Project Title Information Input ...................................................................................................................... 12

Chapter 4. Analysis Option Input ..................................................................................................................................... 14

Chapter 5. Pile Properties Input ...................................................................................................................................... 18

Chapter 6. Pile Top Boundary Conditions ........................................................................................................................ 24

Chapter 7. Pile Bending Stiffness ..................................................................................................................................... 25

Chapter 8. Ground Surface Slope and Pile Batter Slope .................................................................................................. 30

Chapter 9. Soil Material Input .......................................................................................................................................... 32

Chapter 10. Soil Layer Input............................................................................................................................................. 38

Chapter 11. Pile Head Load Input .................................................................................................................................... 40

Chapter 12. Define Point Loads ....................................................................................................................................... 45

Chapter 13. Define Line Loads ......................................................................................................................................... 47

Chapter 14. Define Displacement Loads .......................................................................................................................... 49

Chapter 15. Define Struts and Rotational Springs ........................................................................................................... 51

Chapter 16. Create Surcharges ........................................................................................................................................ 53

Chapter 17. Pile Group Effect .......................................................................................................................................... 55

Chapter 18. Define Pile Settlement Option ..................................................................................................................... 57

Chapter 19. Import CPT Data for Analysis ....................................................................................................................... 59

Chapter 20. Define Unit Option ....................................................................................................................................... 63

Chapter 21. Soil Layer Input Summary ............................................................................................................................ 64

Chapter 22. Pile Input Summary ...................................................................................................................................... 65

Chapter 23. Pile Head Load Summary ............................................................................................................................. 66

Chapter 24. Run Analysis ................................................................................................................................................. 67

Chapter 25. Viewing Analysis Results .............................................................................................................................. 69

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Chapter 26. Viewing P-Y Curves ....................................................................................................................................... 77

Chapter 27. Viewing Equivalent Stiffness at Pile Head .................................................................................................... 81

Chapter 28. Load Settlement Curve at Pile Head ............................................................................................................ 84

Chapter 29. Analysis Report Generator ........................................................................................................................... 87

Appendices ........................................................................................................................................... 91

Appendix A. P-Y curves for lateral force analysis ............................................................................................................ 91

A.1 Soft clay (Matlock) model .................................................................................................................................. 91

A.2 API Soft clay – (API 2014) ................................................................................................................................... 95

A.3 Stiff Clay without Water - (Welch and Reese 1972) .......................................................................................... 99

A.4 Stiff Clay without Water with initial subgrade modulus ................................................................................. 102

A.5 Stiff Clay with Water – Reese et al. (1975) ...................................................................................................... 104

A.6 API Sand - API (2014) ....................................................................................................................................... 108

A.7 Reese Sand – Reese et al. (1974) ..................................................................................................................... 111

A.8 Liquefied Sand – Rollins et al. (2005) .............................................................................................................. 115

A.9 Weak Rock – Reese (1997) .............................................................................................................................. 117

A.10 Strong Rock – Tunner (2006) ......................................................................................................................... 120

A.11 Massive Rock – Liang et al. (2009) ................................................................................................................. 122

A.12 Calcareous Rock – Fragio et al. (1985)........................................................................................................... 126

A.13 Elastic-Plastic Model for soils and rocks ........................................................................................................ 129

A.14 Elastic Model for soils and rocks ................................................................................................................... 133

A.15 Calcareous Soil – Dyson and Randolph (2001) .............................................................................................. 135

A.16 Calcareous Soil – Novello (1999) ................................................................................................................... 137

A.17 Weak Carbonate Rock – Abbs (1983) ............................................................................................................ 139

A.18 Cemented c-phi soil (silt) – Reese et al (1974) .............................................................................................. 141

A.19 User-defined P-Y model ................................................................................................................................. 144

Appendix B. Fleming’s method for pile settlement analysis ......................................................................................... 146

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Appendix C. Examples .................................................................................................................................................... 148

C.1 Example 1 - Steel pipe pile driven into soft clay and sand layers .................................................................... 149

C.2 Example 2 - Steel pipe pile driven into soft clay and sand layers with cyclic loading ..................................... 152

C.3 Example 3 - Steel pipe pile driven into soft clay and sand layers with sloping ground surface ...................... 154

C.4 Example 4 – Bored pile socketed into rock layers ........................................................................................... 156

C.5 Example 5 – Driven Steel Pipe Piles under Distributed Displacement Loads along the Pile ........................... 160

C.6 Example 6 – Pile under Lateral Loading in Soil Layer of Elastic Subgrade Model ............................................ 164

References .......................................................................................................................................... 167

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Chapter 1. Introduction

PileLAT is a finite-element based program that analyses the behaviour of single piles subject to lateral loading

based on nonlinear p-y curves for various soils and rocks. PileLAT is the most comprehensive program for

laterally loaded single piles. It is a very useful tool for designing onshore and offshore pile foundations subject

to lateral loads .

Some of the important features and advantages provided by PileLAT program are summarized as follows:

• Standard window-style dialogs, push buttons, drop menus, list boxes, spreadsheet-type data grid, slide

bars, radio buttons, check boxes and toolbars are used in the program.

• Automatic generation of nonlinear built-in p-y curves for various geotechnical materials such as

cohesive soils, cohesionless soils and rocks. The generated nonlinear p-y curves for each node or any

depth can be viewed, copied, and printed. P-y curve information at any depth is available and can be

accessed before or after the completion of the analysis.

• User-defined p-y curves are supported, and the users can specify custom nonlinear or linear p-y

response of soils for any depths along the pile length.

• Both static and cyclic behaviour of soils can be considered. The user can input the cyclic number of the

cyclic loads.

• Multiple load cases for the applied loads and boundary conditions at the pile top can be specified by the

users and the combined result plots will be generated by the program for all the load cases.

• Pile batter and sloping ground surface can be modelled through an interactive dialogue where the

geometry of the pile batter and ground surface slope can be graphically updated and viewed by the user

with adjusting the positions of the relevant slide bars.

• A full graphical presentation of pile and soil layer geometry is provided within the main program

interface. Important changes in the input data such as pile length, the number of soil layers, soil layer

name, soil layer thickness, soil layer colour, p-y model type, water table position, p-y curve parameters

and pile head loads will be automatically updated in the graph. It is very convenient for the users to

visually view the input changes.

• P-multipliers can be defined by the user for each soil layer to consider the potential pile group effects

for closely spaced piles or any other reduction on the ultimate lateral resistance of the soils. The user

also can use this option to purposely reduce the resistance of the selected soil layers if required.

• The single pile subject to the lateral loads can consist of multiple segments with different section

properties such as section type, size, material stiffness and bending stiffness options.

• Horizontal point loads, moments, line loads and free-field soil displacements can be applied at any

locations along the pile length.

• A wide range of boundary conditions at the pile head can be considered by the program. Those

boundary conditions include free head, rigid head, partially restrained head with elastic rotational

spring, specified deflection with the applied bending moment and specified deflection and rotation.

• A wide range of section types such as circular section, rectangular section, steel H-section, steel pipe

section, octagonal section and user-defined section can be selected by the user.

• The program calculates the load settlement curve at the pile head based on the input ultimate shaft

resistance and ultimate end bearing resistance with using Fleming’s method. The calculated total

ultimate shaft resistance, ultimate end bearing resistance and total ultimate axial pile capacity are

shown on the load-settlement curve graph.

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• The program automatically generates load deflection curves for the stiffness at the pile head such as

horizontal load vs top deflection/rotation, bending moment vs top deflection/rotation and axial force vs

pile head settlement once the analysis is successfully completed.

• PileLAT comes with a separate output program to view all the analysis results and therefore the analysis

input process is purposely separated from the output module, which makes the analysis process more

straightforward.

• The input program will be locked once the analysis is successfully completed. It prevents the users from

changing the inputs once the analysis results are available. If further changes are required for the input,

then the input program should be unlocked before the changes can be made.

• Note that unlocking the input program will result in the deletion of all the existing outputs. This avoids

any accidental changes to the inputs without updating the results and therefore makes the calculation

process more robust.

• The program presents various results graphically along the pile length together with the soil layer

geometry. Detailed analysis results are presented in spreadsheet/grid format and can be easily selected

and copied into the third-party program such as EXCEL for further data processing.

• A separate p-y curve tool is built into the program. The users can check all the information related to

the nonlinear p-y curve at any selected depth. The detailed calculation information relevant to the p-y

curve can be accessed by the users.

• Two different options for nonlinear bending stiffness of pile section are offered by the program: (1)

plastic bending moment and (2) moment curvature curve.

• Both US and Metric units are supported by the program. Switching between US and Metric units is very

straightforward.

• A built-in report generator is provided in PileLAT output program to generate the calculation report

which includes all the input parameters and output results.

• The program generates the mesh in two options: (1) automatic mesh option based on the soil layer

thickness/geometry and (2) uniform mesh option based on the number of the pile elements input by

the users.

• The surcharge loading at the top of each soil layer can be input by the users to consider the increase in

the effective vertical stress within the foundation.

• Elastic horizontal spring (strut) and rotation spring can be applied at each node position to consider the

restraints.

• The program offers the capability of using CPT records for laterally loaded pile analysis. CPT record can

be easily imported into the program and used in the analysis. This feature is very useful to offshore pile

foundation.

• Offshore p-y curve models for calcareous sand and carbonate weak rock are built into the program for

offshore pile foundation design.

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Chapter 2. Start the new file

PileLAT program main interface is shown as below (Figure2-1) when it is firstly started. The users can either

(1) start a new project or (2) open an existing project.

Figure 2-1 Project start dialog in PileLAT

Once the button of “Start new project” is clicked, a default new project with two soil layers is automatically

created and loaded. The default file name is “Newfile.flp” and the file type for PileLAT analysis is “flp”. The

corresponding file path will be shown on the top title bar of the program. The main program interface is

loaded and shown in Figure 2-2.

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Figure 2-2 General layout of the program interface for PileLAT

If “Open File” toolbar button is pressed as shown in Figure 2-3, then the file selection dialog will be loaded

as shown in Figure 2-4 where the user will be able to select and open the existing PileLAT analysis file with

the file type of “flp”.

Figure 2-3 Clicking toolbar button to open existing analysis file

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Figure 2-4 Analysis file selection dialog for PileLAT

The users also can close the current file and start a new analysis by clicking the “New File” toolbar button as

shown in Figure 2-5.

Figure 2-5 Clicking toolbar button to start new analysis file

The following dialog of “New Model Initialization” will appear. A new default analysis file will be created once

the button of “Start a new project” under Quick Start is clicked. Clicking “Open an existing project” button

will invoke the analysis file selection dialog and the users can select and open the existing file.

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Figure 2-6 New model initialization dialog for PileLAT

The main program layout is shown in Figure 2-7. The top tool bar is mainly for the general program input

including soil layer, pile section, CPT record manager, lock/unlock, pile batter and inclined ground surface,

analysis option, title information and pile bending stiffness options. The bottom tool bar is mainly for loading

input such as pile head loads, pile head boundary conditions, free-field soil displacement, line load, point

load and bending moment, strut and rotational spring and surcharge.

Figure 2-7 Main menu and toolbars of PileLAT program

Figure 2-8 shows the tree view area at the left bottom area of the main program interface. Various

important input information such as mesh, pile section, soil layers, pile head loads, analysis option, water

level and pile batter are listed under the relevant sub-branch names. This tree view area provides an

overview of the input parameters and any changes in the input will result in the updates in the tree view

area as well.

Program main menu

Program main top toolbar

Second top toolbar

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Figure 2-8 Main menu and toolbars of PileLAT program

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Chapter 3. Project Title Information Input

The users can input the project title information by selecting the “Project Properties” item under “File” menu

as shown in Figure 3-1 or clicking the toolbar button of “Project Title” as shown in Figure 3-2.

Figure 3-1 Selecting Menu to Define Project Properties

Figure 3-2 Clicking Toolbar to Define Project Properties

The information which can be entered by the users include (1) Project title, (2) Job number, (3) Design

engineer, (4) Client and (5) Description. Figure 3-3 shows the general layout of “Title” dialog.

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Figure 3-3 General layout of “Project Title” Dialog

The following items are created by the program for the user’s reference and cannot be changed by the user

from this dialog:

• Date – the creation date of the project file. The date will also be updated when the project file is

changed and saved.

• File name – the name of the analysis file; and

• File path – the directory path of the program.

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Chapter 4. Analysis Option Input

Various analysis options can be input by the users with selecting the “Analysis Option” item under “Options”

menu (Figure 4-1) or clicking toolbar button of “Analysis Option” from the top toolbar (Figure 4-2).

Figure 4-1 Selecting Menu to Define Analysis Option

Figure 4-2 Clicking Toolbar Button to Define Analysis Option

Figure 4-3 shows the general layout of “Analysis Option” dialog. This dialog provides the user with different

analysis options/information as described below for three main groups: (1) Analysis Option, (2) Mesh Option

and (3) Mesh Information.

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Figure 4-3 Analysis Option for PileLAT

"Analysis Option" group offers two options for the analysis:

• Use soil layers input by users: Selecting this option means that the lateral pile analysis will be carried

out with a wide range of built-in nonlinear p-y curve models for geotechnical materials.

• Use CPT file imported by users: Selecting this option means that the lateral pile analysis will be carried

out based on the imported CPT records. This option is very suitable for offshore pile foundation design.

The more detailed descriptions on how to import CPT data into the program are discussed in Chapter 19

of this manual.

Figure 4-4 Automatic Mesh Option for PileLAT

"Mesh Option" group gives two meshing options:

• Automatic Mesh Generation: The pile element size and number will be automatically generated based

on the option of (1) Very coarse, Coarse, Medium, Fine and Very Fine (Figure 4-4). There is no need for

the users to specify the pile element number. One advantage of this option is that the pile mesh will be

generated based on the soil layer geometry and therefore any pile element will be always within the

same soil layer. It is unlikely that any pile element will cross the soil layer boundaries, i.e., two nodes of

the same element are within different soil layers as shown in Figure 4-5. Note that the element sizes

generated by this option might not be uniform for the ground profile consisting of multiple soil layers

and will vary based on the layer number and thickness values.

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Figure 4-5 Pile element across the layer boundary from manual mesh option

• Manual Input of Mesh Element Number: This option is usually adopted by the conventional finite-

difference-method based analysis for laterally loaded single piles (Figure 4-6, Left). The users will need

to specify the number of pile elements. The element size is uniform and the pile nodes will be evenly

generated along the pile length based on the element number and the pile length. Note that non-

uniform pile element also can be generated under this option if required. Clicking the button of “Edit

Pile Node Position” will invoke the dialog of “Edit Mesh” (Figure 4-6, Right) where the node

position/depth can be manually adjusted to match the soil layer boundaries if required.

Figure 4-6 Manual mesh option and mesh editing table

The numerical analysis control settings can be modified by the users from the “Setting” sub dialog from the

left top area of the main program interface. Clicking “Apply” button will save all the changes into the

program inputs. This is shown in Figure 4-7 and there are five main control parameters for the finite

element analysis:

• Maximum number of load step: This allows the user to change/update the maximum load steps used in

the analysis. The minimum value is 100 and maximum value is 2000. The default value is 1500.

Depending on the nonlinearity of the problem, this value may need to be increased by the user for

This pile element crosses the layer boundary

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convergence.

• Maximum number of iterations for each step: This is the maximum iteration number at each load step

used in the analysis. The minimum value is 30 and maximum value is 300. The default value is 50.

Depending on the nonlinearity of the problem, this value may need to be increased by the user for

convergence.

• Maximum displacement at the pile head: This is the maximum lateral displacement allowed by the

program at the pile head. If the specified value is exceeded, the analysis will be terminated, and no

result outputs will be provided as this usually means that the pile fails under the current loading

conditions.

• Convergence Tolerance: This is the convergence tolerance used to determine whether the equilibrium

conditions are achieved under the current loading conditions. The default value is 1.0E-05 and it shall be

changed with cautions if required. The accuracy of the solutions will be in question if this value is too

high. On the other hand, the analysis will have convergence problem if this value is set to unnecessary

small value in numerical analysis.

• Initial load step: This is the initial load step used in the analysis and the default value is 0.1.

Figure 4-7 Numerical analysis setting parameters

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Chapter 5. Pile Properties Input

Pile section properties can be input by the users with selecting the “Define Pile Cross Section” item under

“Structures” menu (Figure 5-1) or clicking toolbar button of “Pile Section” from the top toolbar (Figure 5-2).

Figure 5-1 Selecting Menu to Define Pile Cross Section

Figure 5-2 Clicking Toolbar to Define Pile Cross Section

Figure 5-3 shows the input dialog for pile section properties. Note that the input dialog also can be opened

by the users with clicking the “Edit” button on the sub-dialog under “Pile” tab at the left side of the main

program, as shown in Figure 5-4. More pile sections can be added or deleted by clicking “Add” or “Delete”

button, Double-clicking the section list will also open the pile section input dialog as shown in Figure 5-3.

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Figure 5-3 Pile section input in PileLAT

Figure 5-4 Pile section input panel in PileLAT

"Cross Section Type" group requires two inputs from the users: (1) Section Type and (2) Section Length. The

single pile analysed by PileLAT program can consist of multiple segments and each pile segment can have

different cross section types and lengths.

The following section types are supported by the program and are selected by clicking the drop-down menu

under “Section Type” label:

• Circular section. Figure 5-5 shows the section dimension and length inputs for the circular section.

Section length is the length of the section. The total pile length used by the program will be the sum of

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all the section lengths input by the users. If only one pile section is defined, then the section length will

be the pile length. The section input parameter for this type is the diameter.

Figure 5-5 Circular section input

• Rectangular section. Figure 5-6 shows the rectangular section inputs. The loading direction is assumed

towards the width direction, as indicated by the arrow direction. The section input parameters for this

type are section width and section height.

Figure 5-6 Rectangular section input

• Octagonal section. Figure 5-7 shows the octagonal section inputs. The loading direction is perpendicular

to the section edge and through the section centre as indicated by the arrow direction. The section

input parameter is the section diameter.

Figure 5-7 Octagonal section input

• H section (strong). Figure 5-8 shows the H section (strong) inputs. The loading direction is towards the

section width (strong direction) as indicated by the arrow direction. The section input parameters are

Flange width (B), Web height (H), Web thickness (t) and Flange thickness (T).

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Figure 5-8 H section (Strong) input

• H section (weak). Figure 5-9 shows the H section (weak) inputs. The loading direction is towards the

section height (weak direction) as indicated by the arrow direction. The section input parameters are

Flange width (B), Web height (H), Web thickness (t) and Flange thickness (T).

Figure 5-9 H section (Weak) input

• Pipe section. Figure 5-10 shows the pipe section inputs. The loading direction is indicated by the arrow

for this section. The section input parameters are outside diameter (D1) and inside diameter (D2).

Figure 5-10 Pipe section input

• User-defined section, Figure 5-11 shows the user-defined section inputs. The loading direction is

towards the section width as indicated by the arrow. The section input parameters are width (B),

moment inertia (I), section area (Ab) and section perimeter (Ls).

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Figure 5-11 User-defined section input

"Material Properties" group (Figure 5-12) is for Young’s modulus (E) input of the pile material, which is usually

either concrete or steel. The input modulus value (E) is used to calculate the elastic bending stiffness (EI) of

the pile section for lateral pile analysis. For the reinforced concrete, Young’s modulus is usually 30 ~ 50 GPa.

For steel pile, Young’s modulus is usually 200 GPa.

Figure 5-12 Material properties input

"Display Settings" group (Figure 5-13) allows the users to specify different line thickness values and colours

representing the different pile sections on the main display dialog. Figure 5-14 shows one example for

laterally loaded single pile with multiple sections which are displayed by different colours and thickness.

Figure 5-13 Display setting input

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Figure 5-14 Laterally loaded single pile with multiple pile sections

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Chapter 6. Pile Top Boundary Conditions

PileLAT supports five different boundary conditions at the pile head (Figure 6-1) which are summarised as

below:

• Free Pile Head. Pile head is free to move laterally and rotate. Usually, pin or hinge connections are

assumed between pile cap and piles.

• Rigid Pile Head. Pile head can move laterally but cannot rotate. Moment will be generated at the pile

head.

• Partially Restrained Pile Head. Rotational spring value needs to be provided in the unit of moment per

unit slope.

• Specified Deflection and Applied Bending Moment.

• Specified Deflection and Specified Rotation.

Figure 6-1 Pile head boundary condition in PileLAT

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Chapter 7. Pile Bending Stiffness

Pile bending stiffness can be input by the users with selecting the “Define Pile Bending Stiffness” item under

“Structures” menu (Figure 7-1) or clicking toolbar button of “Define Pile Bending Stiffness” from the top

toolbar (Figure 7-2).

Figure 7-1 Pile bending stiffness options in PileLAT


PileLAT provides the users with three different options for pile bending stiffness (Figure 7-3) as below:

• Elastic Bending Stiffness Option (Default). This is a default option. This option enables the user to adopt

different pile segments with different bending stiffness in the analysis.

• Plastic bending moment. With this option, the user can adopt different plastic bending moment capacity

for different pile segments in the analysis. Each pile segment can be assigned a different plastic bending

moment capacity to model the nonlinear behaviour of piles under bending.

• Nonlinear bending stiffness. The users can input multiple moment-curvature data set for each pile section

with this option. This is a more advanced approach to consider the nonlinear bending for laterally loaded

piles.

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Pressing the button under “Edit” column invokes the bending stiffness dialog for each section. Figure 7-4

shows the dialog for “Elastic Bending Stiffness” option. Note that the elastic bending stiffness value is

calculated based on the material stiffness and the section properties. It is for viewing only and cannot be

changed by the users for the option of “Elastic bending stiffness”.

Figure 7-4 Elastic Pile bending stiffness in PileLAT

For the option of “Plastic bending moment”, pressing the button under “Edit” column invokes the plastic

bending moment input dialog for the selected pile section, as shown in Figure 7-5. Note that the elastic

bending stiffness value is calculated based on the material stiffness and the section properties. It is for

viewing only and cannot be changed by the users whereas the plastic bending moment field can be modified

by the users. The default plastic bending moment is a large value, which implies the default elastic bending

stiffness for the pile section.

Figure 7-5 Plastic Bending Moment PileLAT

For the selected “Nonlinear bending stiffness” option, pressing the under “Edit” column invokes the dialog

for the nonlinear moment curvature input for the section, as shown in Figure 7-6. More input rows can be

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added by clicking the “Add” button or the number of the input rows can be deleted by clicking “Delete”

button.

Figure 7-6 Nonlinear bending stiffness options in PileLAT

The column of K (1/m) is the curvature value and the column of M (kN.m) is the bending moment value. The

input values can be saved by pressing “Apply” button or closing the dialog with clicking “OK” button or “X”

dialog button. The users also can view the input nonlinear moment curvature relationship by clicking “Plot”

button. There are three different display options: (1) bending moment vs curvature, (2) bending stiffness vs

curvature and (3) bending stiffness vs bending moment. The users can switch into different display options

by clicking the radio buttons.

Figure 7-7 shows the relationship between the bending moment and the curvature. Figure 7-8 shows the

relationship between the bending stiffness and the curvature. Figure 7-9 shows the relationship between the

bending stiffness and the bending moment. Clicking “Copy” button will copy the figure into the clipboard and

it can be then pasted into the third-party programs such as Microsoft word or Excel for reporting purpose.

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Figure 7-7 Graphic plot for the relationship between bending moment and curvature

Figure 7-8 Graphic plot for the relationship between bending stiffness and curvature

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Figure 7-9 Graphic plot for the relationship between bending stiffness and bending moment

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Chapter 8. Ground Surface Slope and Pile Batter Slope

The ground surface angle and/or pile batter slope can be input by the users by clicking “Define Pile Batter

and Surface Slope” item under “Structures” main menu (Figure 8-1) or clicking “Ground Surface Slope and

Pile Batter Slope” icon on the toolbar (Figure 8-2).

Figure 8-1 Selecting Menu to Define Ground Surface Slope and Pile Batter

Figure 8-2 Clicking Toolbar to Define Ground Surface Slope and Pile Batter

The invoked dialog as shown in Figure 8-3 allows the user to input the Pile Top Level, Ground Surface Angle

and Pile Batter.

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Figure 8-3 Ground Surface Slope and Pile Batter Slope Input Dialog

For the ground surface and pile batter slopes, the input range is between -45 and 45 degrees in PileLAT. The

dialog figure will be automatically updated to reflect any change in Pile Batter and Ground Surface Angle by

clicking “Apply” button or pressing “Enter” key on the keyboard. Note that the input pile top elevation value

on this dialog is mainly for result displaying purpose, i.e., the plot of deflections with the level of the node

along the pile.

Free length portion of the pile as shown in the figure is denoted as "Free Length Zone (Null)". This can be

achieved by specifying a "Null" material layer at the ground surface with the layer thickness set to the

cantilever length or free length.

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Chapter 9. Soil Material Input

The users can create soil materials with a wide range of p-y curve models. P-y curve material set input dialog

as shown in Figure 9-3 can be invoked through clicking "Define Soil Materials with P-Y Curves" item under

"Soils" menu (Figure 9-1) or clicking "Material Sets" icon from the toolbar (Figure 9-2).

Figure 9-1 Selecting Menu to Define Soil Materials with P-Y Curves

Figure 9-2 Clicking Toolbar to Define Soil Materials with P-Y Curves

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Figure 9-3 Soil Material Set Input Dialog

Soil material set can be created, deleted or edited through "New", "Delete" and "Edit" buttons. The material

set colour also can be adjusted or updated by clicking "Colour" button (Figure 9-3). In the current version,

maximum 50 different soil material sets can be created by the user.

Figure 9-4 Soil Material Set Color Selection

The detailed p-y curve parameters can be input by the users by pressing “Edit” button or just double-clicking

the material name list. The invoked dialog is shown in Figure 9-5 which is the main interface for the inputs of

various p-y curve properties. Material name is to be defined by the users through the direct text input and

will be used for the subsequent ground model input.

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Figure 9-5 P-y curve models from PileLAT

P-y curve models supported by PileLAT are shown in the dropdown menu as shown in Figure 9-3 and are

summarised as below:

1. Null material

2. API Soft Clay (2014)

3. Matlock Soft Clay

4. Stiff Clay without Water (Reese)

5. Modified Stiff Clay without Water (Brown)

6. Stiff Clay with Water (Reese)

7. Elastic-plastic Clay

8. API Sand (2014)

9. Sand – Reese et al. (1974)

10. Liquefied Sand – Rollins et al. (2005)

11. Elastic-plastic Sand

12. Calcareous Soil – Novello (1999)

13. Calcareous Soil – Dyson and Randolph (2001)

14. Weak Rock – Reese (1997)

15. Strong Rock – Turner (2006)

16. Massive Rock – Liang et al. (1997)

17. Weak Calcareous Rock – Fragio et al. (1985)

18. Weak Carbonate Rock – Abbs (1983)

19. Elastic-Plastic Rock

20. C-phi soil

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21. Elastic Subgrade

22. User-Defined p-y curve

Note that Null material type is mainly used to model the pile cantilever (free length) section above or below

water. In another word, free length or cantilever pile length is defined through adopting a soil layer with Null

material properties at the ground surface. No lateral resistance will be provided by the material set with “Null

Material”.

Detailed descriptions about all the P-Y models supported in PileLAT program and the relevant input

parameters are presented in Appendix A of this manual.

Figure 9-6 Typical Ground Profile with Analysis Results after Soil Layer Input

The ground profile will be automatically updated once the soil layer input is updated and saved. If “Copy

Graph” item under the “File” menu is clicked or the “Copy to Clipboard” toolbar button on the right side of

the program interface is clicked, then the ground profile can be copied into the clipboard and then pasted

into the report if required. A sample of the copied ground profile graph with the analysis results is shown in

Figure 9-6.

The users can use “Display Option” dialog as shown in Figure 9-7 to select or deselect display items as below:

1. Soil layer name

2. Water table

3. Pile length

4. Level and depth

5. Pile section

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6. Layer thickness

7. Pile loading (the applied load at the pile head)

8. Pile toe level

9. Pile mesh

10. Material model

11. Spoil spring

12. Soil strength

13. Point load along the pile length

14. Line load along the pile length

15. Displacement load along the pile length

16. Surcharge load at the top of the soil layers

17. Strut and rotational spring along the pile length

Note that the pile loading display corresponds to the selected load case from the drop-down menu next to

“Pile Head Loads”.

Figure 9-7 Display Options for Ground Profile in PileLAT

The users can test the p-y curves for the input soil materials by clicking the button of “Test” from Figure 9-3.

Figure 9-8 shows the typical dialog of p-y curve testing for the selected material. The users can input the

following values to see the changes in the p-y curves:

• Calculation depth

• Groundwater table depth

• Surcharge at the top of the test layer

• Load cycle number

Note that the inputs are only for viewing and testing the p-y curves of the selected soil material and are not

used in the analysis.

37


Figure 9-8 p-y curve test dialog in PileLAT

The summary of p-y curve calculation can be viewed by the users by clicking the button at the left bottom of the

dialog as shown in Figure 9-8. Figure 9-9 shows the detailed information for the p-y curve calculation, which is very

useful for the users to check the p-y curve inputs.

Figure 9-9 P-Y curve calculation summary dialog

38


Chapter 10. Soil Layer Input

The dialog for creating the ground model with multiple soil layers (as shown in Figure 10-3) can be invoked

by clicking "Define Soil Layers" option under "Soils" menu (Figure 10-1) or "Define Soil Layers" icon from the

top toolbar (Figure 10-2).

Figure 10-1 Selecting Menu to Define Soil Layers

Figure 10-2 Clicking Toolbar to Define Soil Layers

The material sets, soil layer thickness values, water table depth, ground surface elevation and layered soil

correction options can be defined for the analysis.

39


Figure 10-3 Pile Head Load Input Dialog in PileLAT

The soil layers can be added into the ground model by clicking “Add” button. The soil layer can also be

inserted into the ground model by “Insert” button. Clicking “Delete” button will delete the selected soil

layer from the ground model. For each soil layer, the layer thickness value can be input by the users.

The depth of water level below the ground surface and ground surface elevation can be input by the users.

The depth of water table with soil layers will be updated on the right figure once “Enter” button on the

keyboard is pressed or the “Apply” button is clicked.

There are three different soil-layering correction options provided by the program:

• Soil-layering correction for all layers (default option). For this option, the method of Georgiadis (1983)

is used for soil-layering correction for all layers.

• Soil-layering correction for different layer type only. For this option, the method of Georgiadis (1983) is

only used for soil-layering corrections for different soil types.

• No soil-layering correction. For this option, no soil-layering correction is considered for all the soil

layers.

40


Chapter 11. Pile Head Load Input

Pile head loads can be added and edited with “Load” tab dialog as shown in Figure 11-1. Multiple load cases

can be added by the users and the default load case is “Load Case 1” which can be modified by pressing “Edit”

button.

Figure 11-1 Pile Head Load Input Dialog in PileLAT

Figure 11-2 Edit Pile Head Load in PileLAT

Figure 11-2 shows the dialog for editing pile head load. The following pile head load types are supported in

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the program:

1. Free pile head. The required inputs are axial load (Compression load is positive), shear force and

moment as shown in Figure 11-3 . The pile head is free to rotate and move laterally. Left-to-right

direction is considered as positive for shear force and clockwise direction is positive for moment.

2. Rigid pile head. The required inputs are axial load (compression load is positive) and shear force as

shown in Figure 11-4. For this load type, the pile head can move laterally but cannot rotate.

3. Partially restrained pile head. The required inputs are axial load (compression load is positive), shear

force, moment, and rotational spring at the pile head as shown in Figure 11-5 . This load type considers

a rotational restraint at the pile head. Note that a very large value of rotational spring is equivalent to

rigid pile head condition where no rotation can happen at the pile head.

4. Specified deflection and moment. The required inputs are axial load (compression load is positive),

deflection and moment at the pile head as shown in Figure 11-6). The positive direction of the specified

deflection is from left-to-right. The positive direction of moment is clockwise.

5. Specified deflection and rotation. The required inputs are axial load (compression load is positive),

deflection and rotation at the pile head as shown in Figure 11-7. The positive direction of the specified

deflection is from left-to-right. The positive direction of rotation is clockwise.

Figure 11-3 Free pile head load

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Figure 11-4 Rigid pile head load

Figure 11-5 Partially restrained head load

Note that only compressive axial force is considered in PileLAT for P-delta effect and no tension force is

allowed. For cyclic load analysis, the users can define the number of load cycles. The default load cycle

number is 1. To consider the effect of cyclic loading on the soil resistance computed from p-y curves, the

input load cycle number must be in the range between 2 and 5000 cycles.

43


For the additional loads along the pile length such as distributed point loads, line loads or displacement loads,

the user can select whether the input distributed loads will be combined with the defined pile head loads in

the analysis by clicking the checkbox. The details for the distributed point loads, line loads and displacement

loads will be provided in the subsequent chapters.

Figure 11-6 Specified deflection and moment

Figure 11-7 Specified deflection and rotation

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PileLAT program also provides the table-form input for the pile head loads as shown in Figure 11-10. It can

be accessed from “Define Pile Loads” under “Loads” menu (Figure 11-8) or “Pile Head Load” toolbar as shown

in Figure 11-9.

Figure 11-8 Selecting Menu Item to Define Pile Head Loads

Figure 11-9 Clicking Toolbar to Define Pile Head Loads

Figure 11-10 Pile Head Load Table Input Dialog in PileLAT

45


Chapter 12. Define Point Loads

Point loads (horizontal force and moment) along the pile length can be input by the users by clicking "Define

Point Load" option under “Loads” Menu (Figure 12-1) or clicking "Define Point Loads" icon from the second

toolbar (Figure12-2).

Figure 12-1 Selecting Menu to Define Point Loads in PileLAT

Figure 12-2 Clicking Toolbar to Define Point Loads in PileLAT

Figure 12-3 shows the “Create Point Load” dialog. Specific node number can be selected through the drop

menu under the "Node" column. The "Depth" column shows the depth of the node point below the pile head

and this column is not editable. Point loads can be added or deleted through "Add" and "Delete" buttons on

the right side.

Pressing "Apply" button after input will save the input to the analysis file. The input point loads will be

automatically shown in the main graphical area after the dialog is closed. Figure 12-4 shows one example for

this where the input point loads are displayed at the specified node depth locations.

46


Figure 12-3 Create Point Loads in PileLAT

Figure 12-4 Point Loads Display in PileLAT

47


Chapter 13. Define Line Loads

Lateral line loads along the pile length can be input by the users by selecting “Define Line Loads” under “Loads”

Menu (Figure 13-1) or clicking "Define Line Loads" icon from the second toolbar (Figure 13-2).

Figure 13-1 Selecting Menu to Define Line loads in PileLAT

Figure 13-2 Clicking Toolbar to Define Line loads in PileLAT

Figure 13-3 shows the “Create Line Loads” dialog. The minimum node number to form a line load is 2. Like

creating the point loads, specific node number can be selected through the drop menu under the "Node"

column. The "Depth" column shows the depth of the node point below the pile head and this column is not

editable. Line loads can be added or deleted through "Add" and "Delete" buttons on the right side. Pressing

"Apply" button after input will save the input to the analysis file.

The input line loads will be automatically shown in the main graphical area after the dialog is closed. Figure

13-4 shows one example for this where the input line loads are displayed at the specified node depth

locations.

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Figure 13-3 Define Line Loads in PileLAT

Figure 13-4 Lateral Line Loads Display in PileLAT

49


Chapter 14. Define Displacement Loads

Horizontal displacement loads along the pile length can be input by the users in PileLAT by clicking "Create

displacement Load" option under “Loads” Menu (Figure 14-1) or clicking "Create Displacement Loads" icon

from the second toolbar (Figure 14-2).

Figure 14-1 Selecting Menu to Define Displacement Load in PileLAT

Figure 14-2 Clicking Toolbar to Define Displacement Load in PileLAT

Figure 14-3 shows the “Create Displacement Load” dialog. Specific node number can be selected through the

drop menu under the "Node" column. The "Depth" column shows the depth of the node point below the pile

head and this column is not editable. Point loads can be added or deleted through "Add" and "Delete" buttons

on the right side. Pressing "Apply" button after input will save the input to the analysis file.

The input displacement loads will be automatically shown in the main graphical area after the dialog is closed.

Figure 14-4 shows one example for this where the input displacement loads are displayed at the specified

node depth locations.

50


Figure 14-3 Displacement Load Input Dialog in PileLAT

Figure 14-4 Displacement Loads Display in PileLAT

51


Chapter 15. Define Struts and Rotational Springs

The horizontal strut and rotational springs can be input at any node locations to simulate the horizontal

movement or rotational restraints to the pile. The dialog of “Define Struts and Rotational Springs” can be

invoked by selecting "Define Struts and Rotational Springs" option under “Structures” Menu (Figure 15-1) or

clicking " Define Struts and Rotational Springs " icon from the second toolbar (Figure 15-2).

Figure 15-1 Selecting Menu to Define Struts and Rotational Springs in PileLAT

Figure 15-2 Clicking Toolbar to Define Struts and Rotational Springs in PileLAT

Figure 15-3 shows the “Create Struts and Ties” dialog. Specific node number can be selected through the

drop menu under the "Node" column. The "Depth" column shows the depth of the node point below the pile

head and this column is not editable.

Strut spring and rotational spring can be added or deleted through "Add" and "Delete" buttons on the right

side. Pressing "Apply" button after input will save the input to the analysis file. The input strut and rotational

springs will be automatically shown in the main graphical area after the dialog is closed. Figure 15-4 shows

one example for this where the input strut and rotational springs are displayed at the specified node depth

locations.

52


Figure 15-3 Create Struts and Ties in PileLAT

Figure 15-4 Strut and Rotational Springs Display in PileLAT

53


Chapter 16. Create Surcharges

PileLAT can consider the surcharge loading at the soil layer top and therefore the increase of the vertical

effective stress due to the surcharge.

Figure 16-1 Selecting Menu to Define Surcharge Loads in PileLAT

Figure 16-2 Clicking Toolbar to Define Surcharge Loads in PileLAT

The input dialog can be invoked by selecting “Define Surcharge Loads” under “Loads” menu (Figure 16-1) or

clicking “Define Surcharges” icon from the toolbar (Figure 16-2). Figure 16-3 shows the “Create Ground

Surface Surcharge” dialog.

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Figure 16-3 Crete Ground Surface Surcharge in PileLAT

The input layer surcharge loading will be automatically shown in the main graphical area after the dialog is

closed. Figure 16-4 shows one example for this where the input surcharge load is displayed.

Figure 16-4 Layer Top Surcharge Load in PileLAT

55


Chapter 17. Pile Group Effect

In PileLAT, it is very straightforward to specify the P-Multipliers for each soil layer to consider the potential

pile group effects.

Figure 17-1 Selecting Menu to Define Group Effect in PileLAT

Figure 17-2 Clicking Toolbar to Define Group Effect in PileLAT

The dialog for the group effect input option can be invoked by selecting "Group Effect Option" under

"Options" menu (Figure 17-1) or clicking “Pile Group Effect” icon from the toolbar (Figure 17-2).

56


Figure 17-3 P-Multipliers Input Dialog in PileLAT

Two options are available to the users: (1) No Group Effects (Default settings) and (2) Manual settings where

the users can specify the P-Multipliers for each soil layer to consider the potential pile group effects.

If the "User-defined P-Multipliers" option is selected, the input table as shown in Figure 17-3 will appear

which allows the user to input the specific P-Multipliers for each soil layer. The default value for each layer is

1.0.

57


Chapter 18. Define Pile Settlement Option

Pile settlement analysis can be carried out in PileLAT based on Fleming’s approach (Fleming 1992). The pile

settlement analysis inputs can be defined by the users with selecting "Pile Settlement Option" under

"Options" menu as shown in Figure 18-1.

Figure 18-1 Selecting Menu to Define Pile Settlement Option in PileLAT

The method proposed by Fleming (1992) is based on the hyperbolic relationship assumptions for both shaft

and base load displacement responses. Figure 18-2 shows the input dialog for pile settlement analysis in

PileLAT.

Figure 18-2 Define Pile Settlement Option in PileLAT

The analysis requires the following inputs from the users:

• Dimensionless flexibility factor, 𝑀𝑠

58


• Effective length coefficient, 𝐾𝑒

• Soil stiffness at pile base, 𝐸𝑏

• Ultimate shaft resistance for each soil layer, 𝑓𝑠

• Ultimate end bearing resistance for each soil layer, 𝑓𝑏

The detailed descriptions about Fleming’s approach for pile settlement analysis are included in Appendix B

of this manual.

59


Chapter 19. Import CPT Data for Analysis

Cone penetration test (CPT) data can be imported into the program to determining p-y curves for the pile

subject to lateral forces. The toolbar button of “Import CPT Data” as shown in Figure 19-1 will become active

when the analysis option of “Use CPT File Imported by the users” is selected.

Figure 19-1 Clicking Toolbar Button to Import CPT Data

Clicking “Import CPT Data” toolbar button invokes the dialog of CPT file manager as shown in Figure 19-2.

Multiple CPT files can be imported into the program by clicking “Add CPT” button.

Figure 19-2 CPT File Manager in PileLAT

The type of CPT data file can be selected by the users before the CPT data is imported. Currently, the

following file types and options are supported in PileLAT:

• Read data from text file (*.TXT file)

• Read data from DAT file (*.DAT file)

60


• Read data from GEF file (*.GEF file)

• Read data from CSV file (*.CSV file)

• Read data from COR file (*.COR file)

Figure 19-3 Selecting CPT file type to import the CPT data

The main dialog (Figure 19-4) of importing CPT raw data will appear when the “Next” button is clicked. Figure

19-4 shows the data structure of the CPT file before it is imported into the program. The section of “File

Preview” presents a preview of the selected CPT file.

Figure 19-4 Selecting Data Structure to Import CPT Data

The column of “Line” shows the number of the line and the column of “CPT Data” shows the CPT data content

for the associated line. The bottom section of the dialog is “Data Structure” which can be used to define the

input items (Depth, qc, fs, and u2) and units (m, kPa or MPa).

61


“Read the CPT data from the line number” section defines the line number from which the CPT raw data

should be imported. The line number will need to be selected by the users correctly in order to import the

right data block. The line number is usually the first line of the measured CPT data. “Total line number of the

input data” section shows the number of CPT data line. It is read-only and cannot be changed.

Figure 19-5 Selecting Menu to Define Pile Settlement Option in PileLAT

After all the settings are completed, click on “Import” button to import the selected CPT raw data. This will

update the dialog of CPT File Manager with the information of CPT file name, as shown in Figure 19-5. The

button of “Click to View Plot” will become active under the “Plot” column if the CPT file is imported. If the

users click this button, then a CPT plot dialog will be invoked and the imported CPT results will be displayed

on the graphical area, as shown in Figure 19-6.

After importing the CPT data, the users are also able to edit the CPT data if required and this can be achieved

by clicking the button of “Edit CPT Record” button under the “Edit” column. Figure 19-7 shows the dialog for

editing the import CPT data.

Only one CPT file can be used in the pile lateral force analysis although multiple CPT files can be imported

into the program. The “Select” checkbox shall be ticked if the corresponding CPT data file is to be used in the

analysis. Note that the selected CPT data file will be used in the analysis only if the soil layers include the

material set which calculates the nonlinear p-y soil response based on the cone tip resistance (qc) value. The

import CPT data will have no effects on the material sets where the cone tip resistance (qc) value is not used

for p-y response.

62


Figure 19-6 Cone Penetration Test Data Plot in in PileLAT

Figure 19-7 Edit CPT Data in PileLAT

63


Chapter 20. Define Unit Option

PileLAT program provides two units options as below:

• SI Units: This is to select SI Units in the program. It the default option in the program.

• English Units: This is to select English Units in the program.

Those two options can be accessed through the menu under “Options” main menu as shown in the figure

below and it is very straight forward to switch between those two options in the analysis.

Figure 20-1 Selecting Menu to Define Unit in PileLAT

64


Chapter 21. Soil Layer Input Summary

PileLAT provides the user with the option of reviewing soil layer input parameters. Soil layer input summary

dialog can be invoked through selecting "Soil Layer Input Summary" option under "Soil" menu, as shown in

Figure 21-1.

Figure 21-1 Selecting Menu to View Soil Layer Input Summary in PileLAT

The invoked summary table is shown in Figure 21-2 which enables the user to review the detailed soil layer

parameters and spot the input errors if any.

Figure 21-2 Soil Layer Input Summary in PileLAT

65


Chapter 22. Pile Input Summary

Pile input summary table can be viewed through clicking "Pile Input Summary" option under "Structures"

menu as shown in Figure 22-1. It summarises the values of pile input parameters from the user. Multiple

columns for different pile segments can be shown if more than one pile segment is used. The dialog as shown

in Figure 22-2 enables the users to review the input parameters related to the pile type, section type, section

dimension, material stiffness, top connection conditions, bending stiffness and pile batter.

Figure 22-1 Selecting Menu to View Pile Input Summary in PileLAT

Figure 22-2 Pile input summary table in PileLAT

66


Chapter 23. Pile Head Load Summary

Pile head load summary table can be viewed through clicking "Pile Head Load Summary" option under

"Loads" menu, as shown in Figure 23-1. It provides the summary of the pile head load input parameters from

the user. Multiple columns for different pile head loads can be shown if more than one load case are input

by the users.

Figure 23-1 Selecting Menu to View Pile Head Load Summary in PileLAT

The dialog as shown in Figure 23-2 enables the users to review the input pile head loads from the users. The

summarised information include axial load, shear force, moment, specified deflection, specified rotation,

rotational spring, load cycle number, point load, line load and displacement load.

Figure 23-2 Pile Head Loads summary table in PileLAT

67


Chapter 24. Run Analysis

Running the analysis file with the input parameters created from the previous steps can be invoked by clicking

"Run Analysis" under "Analyze" menu (Figure 24-1) or clicking “Run Analysis” button from the top toolbar

(Figure 24-2).

Figure 24-1 Selecting Menu to Run Analysis

Figure 24-2 Clicking Toolbar Button to Run Analysis

The invoked running message dialog as shown in Figure 24-3 provides the calculation progress and analysis

information. The warning messages (if any) will be displayed under the progress bar to show the likely cause

of the problem.

Clicking "OK" button will close the dialog and the user will be able to access the various analysis results if the

analysis run is successful. Otherwise, the user will need to review the input file to find out why the analysis

cannot be successfully completed.

The analysis inputs will be locked and cannot be modified after the analysis is successfully completed. Figure

24-4 shows that the input menus and toolbar buttons will become grey and cannot be accessed. Clicking

“Unlock” button will delete the exiting analysis results and enable the analysis inputs to be modified by the

users. The users can select to either unlock the analysis file or abort the unlocking process (Figure 24-5).

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Figure 24-3 Run Analysis Message Box for an example



69


Chapter 25. Viewing Analysis Results

PileLAT provides an easy way to access various detailed analysis results by clicking the toolbar button of “View

Analysis Results” which will become active once the analysis is successfully completed (Figure 25-1).

Figure 25-1 Clicking Toolbar Button to View Analysis Results

Figure 25-2 shows the PileLAT output window, which has four main areas. The top left area displays the

summary of the pile parameters (Figure 25-3). The bottom left area displays the clickable tree view of the

analysis result item (Figure 25-4).

Figure 25-2 PileLAT Output Window

The top right area is the main graphical area for various analysis result plots (Figure 25-5). A total of four

graphical plots are presented and the users can select the type of result plots. The bottom right area tabulates

all the analysis results in a grid table (Figure 25-6).

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Figure 25-3 Left top area for pile parameter summary

Figure 25-4 Bottom left area for PileLAT result tree view

71


Figure 25-5 Top right area for main graphical result plots

Figure 25-6 Bottom right area for tabulated analysis results

The users can select the result type for each graphic plot with right click of the mouse. Figure 25-7 shows the

following options available in PileLAT output window:

• Deflection (Ux) versus pile length

• Rotation (Rot) versus pile length

• Bending Moment (BM) versus pile length

• Shear Force (SF) versus pile length

• Soil Spring Reaction (SR) versus pile length

• Ultimate Lateral Resistance (Pu) versus pile length

• Soil Spring Stiffness (Ks) versus pile length

• Bending Stiffness (EI) versus pile length

If multiple load cases are input by the users, then the drop-down menu next to “Load Case” can be clicked

to select the load case for which the analysis results will be displayed.

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Figure 25-7 Right-click Menu of PileLAT Output Window

Single plot dialog as shown in Figure 25-8 can be opened by the users by double clicking the result item

under “Pile Results for Selected Load Case” within the tree view area as shown in Figure 25-4 or clicking the

button of “Plot Analysis Results” while selecting the corresponding tree view item.

Figure 25-8 Single plot of the PileLAT analysis results

The users can change the line thickness and colour for the plot under “Plot Setting”. The real-time results

can be also displayed with the movement of mouse over the result plot.

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Multiple plot dialog as shown in Figure 25-11 can be opened by the users by double clicking the result item

under “Pile Results for All Load Cases” within the tree view area as shown in Figure 25-4 or clicking the

button of “Plot Analysis Results” while selecting the corresponding tree view item.

It also can be opened by clicking “Multiple Result Plot” toolbar button as shown in Figure 25-9 or selecting

“Results Plot for Multiple Load Cases” under “Tools” menu as shown in Figure 25-10.

Figure 25-9 Clicking toolbar to open multiple lot of the PileLAT analysis results

Figure 25-10 Selecting menu to open multiple lot of the PileLAT analysis results

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Figure 25-11 Multiple plot of the PileLAT analysis results

As shown in Figure 25-11, the users can select different analysis result type to plot by clicking the drop-

down menu next to the label of “Multiple Results Plot Selection”. All the load cases will be listed within the

grid table next to the graphical plot area. The users can select the load cases which they want to display in

the main graphical area. This can be achieved by selecting or deselecting the load case items and clicking

the “Apply” button. Clicking “Select ALL” will select all the load cases and clicking “Select None” will

deselect all the load cases.

PileLAT allows the users to compare the analysis results with other programs or measured data and this can

be achieved by clicking the button of “Customer Data”. Figure 25-12 shows the dialog to input the

comparison data. The number of data can be defined next to the label of “Data row number” and the grid

table will be updated with the input row number after the button of “Apply” is clicked. The users can define

the data name in the text box next to “Data Name” label. The grid table supports copy and paste and

therefore the users can copy the data in spreadsheet and paste here and there is no need to type the value

one by one. Note that the user customer data will be only shown on the graphical area with the PileLAT

analysis results if the checkbox of “Include the user analysis data in the plot” at the dialog bottom is ticked.

Figure 25-13 shows the comparison plots between PileLAT and RSPile for Example 4 in Appendix C. More

details about this example can be found in Appendix C.

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Figure 25-12 Multiple plot of the PileLAT analysis results

76


Figure 25-13 Comparison results for deflection and bending moment for Example 4 in Appendix C

77


Chapter 26. Viewing P-Y Curves

In PileLAT, once the analysis is successfully completed, the user can access the various analysis results. The

dialog for p-y curve plot can be invoked by clicking the "P-Y Curve Plots for Selected Nodes" option under

"Tools" menu as shown in Figure 26-1 or “P-y Curves Plot” from the toolbar as shown in Figure 26-2.

Figure 26-1 Selecting menu to open P-Y curve plots

Figure 26-2 Clicking toolbar to open P-Y curve plots

P-y curves for all the nodes can be selected and viewed by the user through p-y Curve Plot Dialog as shown

in Figure 26-3. Plot or update the p-y curve plots can be done through the following steps:

• Step 1: Tick the check box for the pile node number where you want to view the results. Note that

multiple node points can be selected;

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• Step 2: Click the "Plot/Update" button at the bottom of the table to update the p-y curve plots.

Figure 26-3 P-y Curve Plot dialog in PileLAT

For each node point listed in the table, other relevant information such as Depth, Level, and p-y model type

are also displayed for the user's information. The background colour of row in the table follows the colour

of the soil layer.

Figure 26-4 Tabulated results for p-y curves

If required, detailed p-y curve results can be accessed through right clicking and selecting the floating menu

item of "Table" as shown in Figure 26-4. A new window with grid table as shown in Figure 26-5 will be

invoked with "y" lateral displacement (mm or inch) and "p" mobilised soil reaction (kN/m or lbf/in) for the

selected node points along the pile length.

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Figure 26-5 Tabulated p-y Curve results

Figure 26-6 Selecting node depth for tabulated p-y Curve results

The users can click the drop-down menu next to the label of “Node” to select the node depth for the

tabulated p-y curve results. This is shown in Figure 26-6. PileLAT enables the user to copy the relevant results

on the graph. This can be done by clicking “Copy ” menu as shown in Figure 26-4. The copied graph can be

80


easily pasted into the third-party application for reporting purpose as shown in Figure 26-7.

Figure 26-7 Copied p-y curves graph from PileLAT results

81


Chapter 27. Viewing Equivalent Stiffness at Pile Head

In PileLAT, the users can view various equivalent stiffness at pile head once the analysis is successfully

completed. The dialog for the equivalent stiffness at pile head can be invoked by clicking the "Equivalent

Stiffness at Pile Head" option under "Tools" menu as shown in Figure 27-1 or “Equivalent Stiffness at Pile

Head” from the toolbar as shown in Figure 27-2.

Figure 27-1 Selecting menu to view equivalent stiffness at pile head

Figure 27-2 Clicking toolbar to view equivalent stiffness at pile head

Figure 27-3 shows the dialog of equivalent stiffness at pile head which presents the graphical plot of various

equivalent stiffness at pile head and the tabulated results. The following equivalent stiffness values at pile

head are provided in PileLAT (Figure 27-4):

• Pile head axial load/head settlement (K11)

• Pile head shear force/deflection (K22)

• Pile head shear force/rotation (K23)

• Pile head bending moment/deflection (K32)

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• Pile head bending moment/rotation (K33)

Figure 27-3 Equivalent stiffness at pile head in PileLAT

Figure 27-4 Selecting the type of equivalent stiffness at pile head in PileLAT

Each equivalent stiffness at pile head can be plotted against either displacement (deflection/rotation) or

loads (bending moment/shear force). Note that all the stiffness plots depend on the applied loads at the

pile head. If the applied bending moment/shear force at the pile head is zero, then only a horizontal line

will be displayed.

Right click on the graphical area will show a floating menu for the “Copy” function as shown in Figure 27-5.

The equivalent stiffness plot can be copied into the clipboard and then pasted into the third-party

application for reporting purpose.

83


Figure 27-5 Copying Equivalent stiffness at pile head in PileLAT

84


Chapter 28. Load Settlement Curve at Pile Head

PileLAT predicts the pile settlement under compressive axial loading at the pile head. This unique feature is

very useful. It enables the users to estimate the axial load settlement curve at the pile head when lateral

force analysis is carried out without the need to set up a separate analysis file for pile settlement analysis.

The only additional input is the axial load at the pile head.

The load settlement curve at the pile head can be viewed by selecting “Load Settlement Curve at Pile Head”

under “Tools” menu as shown in Figure 28-1 or clicking the toolbar button of “Load Settlement Curve” as

shown in Figure 28-2.

Figure 28-1 Selecting menu to view load settlement curve at pile head

Figure 28-2 Clicking toolbar to view load settlement curve at pile head

Figure 28-3 shows the “Axial Load Settlement Curve” dialog. Load-settlement curve is generated by the

program for the specified axial loading at the pile head. The ultimate shaft resistance, ultimate end bearing

resistance and ultimate axial pile capacity are calculated by the program and the results are shown on the

load-settlement curve graph.

85


Figure 28-3 Load settlement curve at pile head

Figure 28-4 Load settlement curve dialog

The tabulated results of the load settlement curve at pile head can be viewed by the users with mouse right

click on the graphical area and selecting the menu of “Show Table” (Figure 28-5). The tabulated results are

shown in Figure 28-5. It can be seen that the load and settlement results at the pile head are presented in

the grid table.

86


Figure 28-5 Tabulated load settlement curve results

PileLAT also enables the user to copy or print the axial load settlement curve results on the graph. This can

be done by clicking “Copy” menu as shown in Figure 28-4. The copied graph as shown in Figure 28-6 can be

easily pasted into the third-party application for reporting purpose if required.

Figure 28-6 Copied axial load pile settlement curve

87


Chapter 29. Analysis Report Generator

PileLAT analysis results can be saved into a text report through the report generator tool. The users can access

the tool by selecting “Report Generator” under “File” menu from the output main window as shown in Figure

29-1 or clicking “Report Generator” toolbar button as shown in Figure 29-2.

Figure 29-1 Selecting menu to generate the analysis report

Figure 29-2 Clicking toolbar to generate the analysis report

Figure 29.3 shows the typical text window of PileLAT Output Report which includes all the input and output

information for the analysis. The outputs can be saved into the RTF file by clicking “Save As” under “File”

menu as shown in Figure 29-4. Figure 29-5 shows the PileLAT output “RTF” file opened in WordPad

program. Note that the output file can be opened in Microsoft Word as well.

88


Figure 29-3 PileLAT output report window

Figure 29-4 Save PileLAT output to RTF file

89


Figure 29-5 Open PileLAT output RFT file in WordPad

The detailed analysis results shown in the grid table of the output window can be exported into CSV file

which can be open by Microsoft Excel program. This can be done by selecting “Export to CSV File” under

“File” menu from the output main window as shown in Figure 29-1. Figure 29-6 shows the save dialog for

exporting PileLAT results into CSV file. The program will automatically open the saved CSV file with

Microsoft Excel program (if installed) after the “Save” button is clicked.

90


Figure 29-6 Export PileLAT results into CSV file

91


APPENDICES

Appendix A. P-Y curves for lateral force analysis

A.1 Soft clay (Matlock) model

P-Y curves for soft clay with water based on the method established by Matlock (1970) are shown below for

both static and cyclic loading conditions.

Figure A.1-1 P-Y curve fo r soft clay (Matlock) model under static loading condition

1

0.5

𝑃 𝑃𝑢Τ

𝑌 𝑌50Τ

0 1 8

൬𝑃

𝑃𝑢൰ = 0.5 ൬

𝑌

𝑌50൰

13

92


Figure A.1-2 P-Y curve for soft clay (Matlock) model under cyclic loading condition

The ultimate resistance (Pu) of soft clay increases with the depth and the smaller of the values based on the

following relationships is adopted:

𝑃𝑢 = 𝑐𝑢𝐷 (3 +𝛾′

𝑐𝑢𝑋 + 𝐽

𝑋

𝐷) for 𝑋 ≤ 𝑋𝑅 (A.1-1)

𝑃𝑢 = 9𝑐𝑢𝐷 for 𝑋 ≥ 𝑋𝑅 (A.1-2)

Where:

Pu = ultimate soil resistance per unit length

cu = undrained shear strength

σn′ = vertical effective stress

D = pile diameter

J = dimensionless empirical constant (0.5 for soft clays and 0.25 for medium clay). In PileLAT, the default

value of 0.25 is adopted.

X = depth below soil surface

XR = transition depth where both equations produce the same value.

1

0.5

𝑃 𝑃𝑢Τ

𝑌 𝑌50Τ

0 1 3

For 𝑋 ≥ 𝑋𝑛

15

0.72

0.72𝑋

𝑋𝑟

93


The reference displacement 𝑌50 is calculated by the equation below:

𝑌50 = 2.5휀50𝐷 (A.1-3)

where 휀50 is the strain at one-half the maximum stress for an undrained tri-axial compression test. If no

direct laboratory data is available, the following recommended values of 휀50 are adopted in PileLAT for clays:

Table A.1-1 Recommendation values for Strain Factor of clays

Undrained Shear Strength (kPa) Strain Factor, 𝜺𝟓𝟎

≤ 24 0.02

24 ~ 48 0.01

48 ~ 96 0.007

96 ~ 200 0.005

≥ 200 0.004

The required input parameters for soft clay (Matlock) in PileLAT are shown in Figure A.1-3 and summarised

as follows:

• Total Unit Weight: The total unit weight of the soil material

• Undrained Shear Strength: Undrained shear strength at the top of the soil layer with the input material

set.

• Su – Rate of Change: Increase rate of the undrained shear strength from the top of the soil layer with the

input material set.

• Strain Factor, Eps50: It is the strain at one-half the maximum stress for an undrained tri-axial compression

test and is based on the recommendations in Table A.1-1.

94


Figure A.1-3 P-Y parameter input dialog for soft clay (Matlock) model in PileLAT

95


A.2 API Soft clay – (API 2014)

Soft clay also can be modelled by the method recommended in API RP 2GEO 1st Edition (2014), where the

ultimate resistance (Pu) of soft clay is determined in the same way as Matlock (1970). The only difference is

that the piece-wise curves are used as shown in the figures below for both static and cyclic loading conditions.

Figure A.2-1 P-Y curve for soft clay (API) model under static loading condition

Figure A.2-2 P-Y curve points for API Soft Clay model (extracted from API RP 2GEO, 2014)

1

0.5

𝑃 𝑃𝑢Τ

𝑌 𝑌𝑐Τ

0 1

8

𝑃𝑢

3

0.72

1.00

0.1

0.33

0.23

0.3

96


Figure A.2-3 P-Y curve for soft clay (API) model under cyclic loading condition

Figure A.2-4 P-Y curve points for API Soft Clay model (extracted from API RP 2GEO, 2014)

The reference displacement 𝑌𝑐 is calculated by the equation below:

1

0.5

𝑃 𝑃𝑢Τ

𝑌 𝑌𝑐Τ

0 1 3

For 𝑋 ≥ 𝑋𝑛

15

0.72

0.72𝑋

𝑋𝑟

0.33

0.23

0.3 0.1

97


𝑌𝑐 = 2.5휀50𝐷 (A-4)

where 휀50 is the strain at one-half the maximum stress for an undrained tri-axial compression test and is

based on the recommendations in Table A.1-1.

The required input parameters for API soft clay model in PileLAT are shown in Figure A.2-5 and summarised

as follows:



set.


input material set.



• J: Dimensionless empirical constant with values ranging from 0.25 to 0.5. Note that a value of 0.5 is usually

adopted for Gulf of Mexico clays.

Figure A.2-5 P-Y parameter input dialog for soft clay (API) model in PileLAT

98


99


A.3 Stiff Clay without Water - (Welch and Reese 1972)

The following figures show the P-Y curves for stiff clay without water based on Welch and Reese (1972) under

both static and cyclic loading conditions.

Figure A.3-1 P-Y curve for stiff clay without water model under static loading condition

𝑃𝑢

𝑃

𝑌 0

16𝑌50

൬𝑃

𝑃𝑢൰ = 0.5 ൬

𝑌

𝑌50൰

14

100


Figure A.3-2 P-Y curve for stiff clay without water model under cyclic loading condition

The ultimate soil resistance per unit length of pile, Pu and the reference displacement 𝑌50 is determined by

the procedure as described in Appendix A.1.

The required input parameters for stiff clay without water model in PileLAT are shown in Figure A.3-3 and

summarised as follows:



set.


input material set.



𝑃𝑢

𝑃

𝑌 0

16𝑌50 + 9.6𝑌50𝑙𝑜𝑔𝑁1

𝑁1 𝑁2

𝑁3

𝑌𝑐 = 𝑌𝑠 + 𝑌50𝐶𝑙𝑜𝑔𝑁4

𝑁4




16𝑌50 + 9.6𝑌50𝑙𝑜𝑔𝑁2 16𝑌50 + 9.6𝑌50𝑙𝑜𝑔𝑁3

16𝑌50 + 9.6𝑌50𝑙𝑜𝑔𝑁4

101


Figure A.3-3 P-Y parameter input dialog for stiff clay without water model in PileLAT

102


A.4 Stiff Clay without Water with initial subgrade modulus

This model is similar to stiff clay without water based on the method by Welch and Reese (1972) except for

that the initial slope follows the recommendations on the model of stiff clay with water by Reese et al. (1975).

The initial straight-line portion of the P-Y curve is calculated by multiplying the depth, X by Ks. The values of

Ks are determined based on the values of undrained shear strength as follows (Reese and Van Impe, 2001):

Table A.4-1 Recommended on the initial slope of the p-y curve for stiff clay

Ks (MN/m3)

Undrained shear strength (kPa)

50 ~ 100 100 ~ 200 300 ~ 400

Static Loading 135 270 540

Cyclic Loading 55 110 217

The following figures show the P-Y curves for the stiff clay with initial modulus based on the recommendation

of Brown (2002).

Figure A.4-1 P-Y curve for the stiff clay with initial modulus model under static loading condition

𝑃𝑢

𝑃

𝑌

0 16𝑌50

൬𝑃

𝑃𝑢൰ = 0.5 ൬

𝑌

𝑌50൰

14

𝐸𝑠𝑖 = 𝐾𝑠𝑋

103


The required input parameters for stiff clay without water model in PileLAT are shown in Figure A.3-3 and




set.


input material set.



• Subgrade Modulus, Ks: It is the initial slope of the p-y curve as shown in Table A.4-1.

Figure A.4-2 P-Y parameter input dialog for the stiff clay with initial modulus model in PileLAT

104


A.5 Stiff Clay with Water – Reese et al. (1975)

P-Y curves for stiff clay with water are based on the method established by Reese et al. (1975). The ultimate

resistance (Pc) of stiff clay with water is calculated based on the equations as follows:

𝑃𝑐𝑠 = 2𝑐𝑎𝐷 + 𝛾′𝐷𝑋 + 2.83𝑐𝑎𝑋 (A.5-1)

𝑃𝑐𝑑 = 11𝑐𝑢𝐷 (A.5-2)

𝑃𝑐 = min (𝑃𝑐𝑠, 𝑃𝑐𝑡) (A.5-3)

where:

𝑃𝑐𝑠 = ultimate soil resistance per length for stiff clay with water near the ground surface

𝑃𝑐𝑑 = ultimate soil resistance per length for stiff clay with water at deep depth

𝑐𝑎 = average undrained shear strength over the calculation depth

𝑐𝑢 = undrained shear strength

𝛾′ = effective soil unit weight

D = pile diameter


The initial straight-line portion of the P-Y curve is calculated by multiplying the depth, X by Ks. The values of

Ks are determined based on the values of undrained shear strength as follows (Reese and Van Impe, 2001)

as shown in Table A.4-1.

105


Figure A.5-1 P-Y curve for the stiff clay with water model under static loading condition

Figure A.5-2 P-Y curve for the stiff clay with water model under cyclic loading condition

𝑃

𝑌 0

𝑌50

𝐸𝑠𝑠 = −0.0625𝑃𝑐

𝑌50

0.5𝑃𝑐

𝑌50 = 휀50𝐷

6𝐴𝑠𝑌50 18𝐴𝑠𝑌50 𝐴𝑠𝑌50

𝐸𝑠𝑖 = 𝐾𝑠𝑋

𝑃 =𝑃𝑐

2ඨ

𝑌

𝑌50

∆𝑃 = 0.055𝑃𝑐 ൬𝑌 − 𝐴𝑠𝑌50

𝐴𝑠𝑌50൰

1.25

𝑃

𝑌 0

0.45𝑌𝑝

𝐸𝑠𝑐 = −0.085𝑃𝑐

𝑌50

𝐴𝑐𝑃𝑐

𝑌50 = 휀50𝐷

0.6𝑌𝑝 1.8𝑌𝑝

𝐸𝑠𝑖 = 𝐾𝑐𝑋

𝑌𝑝 = 4.1𝐴𝑠𝑌50

𝑃 = 𝐴𝑐𝑃𝑐 ൭1 − ቤ𝑌 − 0.45𝑌𝑝

0.45𝑌𝑝ቤ

2.5

൱

𝐸𝑠𝑖=𝐾𝑐𝑋

106


Figure A.5-3 Variation of As and Ac parameters with the depth for the stiff clay with water model

Figures A.5-1 and A.5-2 show the P-Y curves for the stiff clay with water model under both static and cyclic

loading conditions. 𝑌50 and 𝑌𝑝 are calculated by the following equations:

𝑌50 = 휀50𝐷 (A.5-4)

𝑌𝑝 = 4.1𝐴𝑠𝑌50 (A.5-5)

where the strain factor 휀50 is based on the Table A.1-1. The parameters, As and Ac can be determined from

Figure A.5-3.

The required input parameters for stiff clay with water model in PileLAT are shown in Figure A.5-4 and




set.


input material set.



• Subgrade Modulus, Ks: It is the initial slope of the p-y curve as shown in Table A.4-1.

107


Figure A.5-4 P-Y parameter input dialog for the stiff clay with water model in PileLAT

108


A.6 API Sand - API (2014)

For API Sand model (API 2014), the ultimate lateral bearing capacity for sand at shallow depth is calculated

as:

𝑃𝑢𝑠 = (𝐶1𝑋 + 𝐶2𝐷)𝛾′𝑋 (A.6-1)

𝑃𝑢𝑑 = 𝐶3𝐷𝛾′𝑋 (A.6-2)

where:

Pus = ultimate resistance at the shallow depth;

Pud = ultimate resistance at the deep depth;

γ′ = effective soil weight

𝑋 = depth

C1,C2,C3 = coefficients determined from Figure A.6-2 of API RP 2GEO 1st Edition (2014).

D = Pile Diameter

P-Y curves for API Sand under both static and cyclic loading conditions are shown in the figure below.

Figure A.6-1 P-Y curve for API Sand model under both static and cyclic loading condition

𝑃

𝑌

0

Cyclic

Static

109


The lateral soil resistance-deflection (P-Y) relationship is described by:

𝑃 = 𝐴𝑃𝑢𝑡𝑎𝑛ℎ [𝐾𝐷

𝐴𝑃𝑢𝑦]

(A.6-3)

where:

P = actual lateral resistance

A = Factor to account for cyclic or static loading conditions (0.9 for cyclic loading, max(3.0 − 0.8H DΤ , 0.9)

for static loading)

K = initial modulus of subgrade reaction which can be determined from Figure A.6-3 extracted from API RP

2GEO 1st Edition (2014).

Y = lateral deflection

Figure A.6-2 Variation of C1, C2 and C3 with the friction angle for API sand model (after API 2014)

Figure A.6-3 Variation of initial modulus of subgrade with the friction angle for API sand model (after API 2014)

110


The required input parameters for API Sand model are shown in Figure A.6-4 and summarised as below:


• Effective cohesion, c’: Effective cohesion of the soil material.

• Effective Friction Angle: Effective friction angle of the soil material.

• Subgrade Modulus: Initial subgrade modulus adopted in the p-y curve of API sand model.

Figure A.6-4 P-Y parameter input dialog for the API Sand in PileLAT

111


A.7 Reese Sand – Reese et al. (1974)

P-Y curves for sand based on Reese et al. (1974) for both static and cyclic loading conditions are shown in the

figure below.

Figure A.7-1 P-Y curve for Reese Sand model under both static and cyclic loading condition

The ultimate resistance of sand varies from a value determined by equation (A.7-1) at shallow depths to a

value determined by equation (A.7-2) at deep depths. The depth of transition ( Xt ) is determined by

comparing the value of each equation at the specified depths.

The ultimate resistance of sand at the shallow depths is determined according to:

𝑃𝑠𝑡 = 𝛾𝑋 [𝐾0𝑋 tan 𝜑′ sin 𝛽

tan(𝛽 − 𝜑′) cos 𝛼+

tan 𝛽

tan(𝛽 − 𝜑′)(𝐷 + 𝑋 tan 𝛽 tan 𝛼)

+ 𝐾0 tan 𝛽 (tan 𝜑′ sin 𝛽 − tan 𝛼) − 𝐾𝑎𝐷]

(A.7-1)

and the ultimate resistance of sand at deep depths is determined according to:

𝑃𝑠𝑑 = 𝛾𝑋𝐷{𝐾𝑎[(tan 𝛽)8 − 1] + 𝐾0 tan 𝜑′ (tan 𝛽)4} (A.7-2)

where:

𝐷 60Τ 0

3𝐷 80Τ

𝐾

𝑌𝑘

𝑃𝑘

𝐾𝑠X

𝑃

𝑌

𝑀

𝑈 𝑃𝑚

𝑃𝑢

𝑌𝑢 𝑌𝑚

𝑋 = 𝑋1

𝑋 = 𝑋2

𝑃𝑢 − 𝑃𝑚

𝑌𝑢 − 𝑌𝑚

112



K0 = coefficient of earth pressure at rest

φ′ = angle of internal friction of sand

β = 45° +φ′

2

α = φ′

2

Ka = [tan (45° −φ′

2)]

2

D = pile diameter

Ps = min (Pst, Psd)

Pu = AsPs or Pu = AcPs

Pm = BsPs or Pm = BcPs

The empirical parameters As, Ac, Bs and Bc can be determined through the following figures.

Figure A.7-2 Variation of As and Ac with the depth for Reese sand model (After Reese at al. 1974)

113


Figure A.7-3 Variation of Bs and Bc with the depth for Reese sand model (After Reese et al. 1974)

114


The required input parameters for Reese Sand model are shown in Figure A.7-4 and summarised as below:




• Subgrade Modulus: Initial subgrade modulus adopted in the p-y curve of API sand model.

Figure A.7-4 P-Y parameter input dialog for the Reese Sand in PileLAT

115


A.8 Liquefied Sand – Rollins et al. (2005)

P-Y curves for liquefied sand is based on the works of Rollins et al. (2005) and is shown in the figure below.

No additional advanced soil parameter inputs are required for this soil model. The program will automatically

calculate the P-Y response during the analysis.

Figure A.8-1 P-Y curve for Liquefied Sand

The following equations are used to produce the curve:

𝑃0.3𝑚 = 𝐴(𝐵𝑦)𝐶 ≤ 15 𝑘𝑁/𝑚 (A.8-1)

𝑃𝑑 = 3.81 ln|𝐷| + 5.6 for 0.3 m < D < 2.6 m (A.8-2)

𝑃 = 𝑃0.3𝑚𝑃𝑑 (A.8-3)

𝐴 = 3 × 10−7(𝑋 + 1)6.05 (A.8-4)

𝐵 = 2.80(𝑋 + 1)0.11 (A.8-5)

𝐶 = 2.85(𝑋 + 1)−0.41 (A.8-6)

Note that it could be possible that the maximum value of P is reached when the lateral deflection is less than

150 mm.

The required input parameters for Liquefied Sand model are shown in Figure A.8-2 and summarised as below:

𝑃

𝑌 0

150mm

𝑃𝑢

116



Figure A.8-2 P-Y parameter input dialog for the Liquefied Sand in PileLAT

117


A.9 Weak Rock – Reese (1997)

P-Y curves for weak rock are calculated using the method established by Reese (1997) and shown in the figure

below.

Figure A.9-1 P-Y curve for Weak Rock – Reese (1997)

The ultimate resistance of weak rock is determined according to the following equations:

Pur = αrQurD ൬1 + 1.4Xr

D൰

(For 0 ≤ Xr ≤ 3D)

(A.9-1)

Pur = 5.2αrQurD

(For Xr ≥ 3D) (A.9-2)

where 𝑃𝑢𝑟 is ultimate soil resistance per unit length; αr is the strength reduction factor; Qur is the

unconfined compressive strength of rock; D = pile diameter and Xr = depth below rock surface.

The lateral resistance-deflection (P-Y) relationship for weak rock is represented by a three-segment curve.

The relationship is described by:

𝑃 = 𝑀𝑖𝑟𝑌 (A.9-3)

118


For 𝑌 ≤ 𝑌𝐴

𝑃 =𝑃𝑢𝑟

2൬

𝑌

𝑌𝑚൰

0.25

For 𝑌 ≥ 𝑌𝐴 and 𝑃 ≤ 𝑃𝑢𝑟

(A.9-4)

𝑃 = 𝑃𝑢𝑟

For 𝑌 ≥ 16𝑌𝑚 (A.9-5)

𝑌𝐴 can be found by solving the following equation:

𝑌𝐴 = [𝑃𝑢𝑟

2(𝑌𝑚)0.25𝑀𝑖𝑟]

1.333

(A.9-6)

The initial modulus / slope of the P-Y curve, 𝑀𝑖𝑟can be determined by:

𝑀𝑖𝑟 = 𝑘𝑖𝑟𝐸𝑚 (A.9-7)

Where 𝐸𝑚 is the rock mass modulus and 𝑘𝑖𝑟 is a dimensionless factor calculated by:

𝑘𝑖𝑟 = 100 +400𝑋𝑟

3𝐷

(For 0 ≤ 𝑋𝑟 ≤ 3𝐷)

(A.9-8)

𝑘𝑖𝑟 = 500

(For 𝑋𝑟 ≥ 3𝐷) (A.9-9)

The parameter 𝑌𝑚 can be determined by:

𝑌𝑚 = 휀𝑟𝑚𝐷 (A.9-10)

where εrm is a dimensionless constant and normally ranges from 0.0005 to 0.00005 in the analysis.

The required input parameters for Weak Rock (Reese) model are shown in the figure below on the “advanced”

page of the soil layer input dialog:


• UCS: Unconfined compressive strength (kPa)

• UCS Strength – Rate of change: The increase rate of the unconfined compressive strength (UCS) with the

depth from the top of the soil layer

119


• Strain Factor, Eps-rm: It is εrm dimensionless constant ranging from 0.00005 to 0.0005;

• Mass Modulus, Em: The default value of Em is determined by the method of Rowe and Armitage (1984):

𝐸𝑚 = 215√𝜎𝑐 (MPa) where 𝜎𝑐 is the unconfined compressive strength of rock;

• RQD, which is rock quality designation parameter and varies between 0 and 100%;

• Mass Modulus – Rate of Change, Em-inc: It is the rock mass modulus increment rate with the layer depth

from the layer top.

Figure A.9-2 P-Y parameter input dialog for the Weak Rock in PileLAT

120


A.10 Strong Rock – Tunner (2006)

P-Y curves for strong rock are calculated using the method by Turner (2006) and are shown in the figure below.

Figure A.10-1 P-Y curve for Strong Rock

The ultimate resistance of strong rock is given by the following equation:

𝑃𝑢 = 𝐵𝑆𝑢

where B is the pile diameter and Su is the half of the unconfined compressive strength of the strong rock.

The required input parameters for strong rock model are shown in Figure A.10-2:





121


Figure A.10-2 P-Y parameter input dialog for the Strong Rock in PileLAT

122


A.11 Massive Rock – Liang et al. (2009)

P-Y curves for massive rock are calculated using the method by Liang et al. (2009) and are shown in the figure

below.

Figure A.11-1 P-Y curve for Massive Rock

The ultimate resistance of massive rock at the shallow depth is given by the following equations:

𝑃𝑢𝑠 = 2𝐶1 cos 𝜃 sin 𝛽 + 𝐶2 sin 𝛽 − 2𝐶4 sin 𝜃 − C5

𝐶1 = 𝐻 tan 𝛽 sec 𝜃 ൬𝑐′ + 𝐾𝑜𝜎𝑣0′ tan ∅′ +

𝐻

2𝐾𝑜𝛾′ tan ∅′൰

𝐶2 = 𝐶3 tan ∅′ + 𝑐′(𝐷 sec 𝛽 + 2𝐻 tan 𝛽 sec 𝛽 tan 𝜃)

𝐶3 =𝐷 tan 𝛽 (𝜎𝑣𝑜

′ + 𝐻𝛾′) + 𝐻(tan 𝛽)2 tan 𝜃(2𝜎𝑣0′ + 𝐻𝛾′) + 𝑐′(𝐷 + 2𝐻 tan 𝛽 tan 𝜃) + 2𝐶1 cos 𝛽 cos 𝜃

sin 𝛽 − tan ∅′ cos 𝛽

𝐶4 = 𝐾0𝐻 tan 𝛽 sec 𝜃 (𝜎𝑣0′ +

𝛾′𝐻

2)

𝐶5 = 𝛾′𝐾𝑎(𝐻 − 𝑧0)𝐷

𝛽 = 45° +∅′

2

𝜃 =∅′

2

123


𝐾𝑎 = 𝑡𝑎𝑛2 (45° −∅′

2)

𝐾0 = 1 − sin ∅′

𝑧0 =2𝑐′

𝛾′√𝐾𝑎

−𝜎𝑣0

′

𝛾′

where 𝑐′ is the effective cohesion, ∅′ is the effective friction angle, 𝛾′ is the effective unit weight and D

is the pile diameter/width.

The ultimate resistance of massive rock at the deep depth is given by the following equations:

𝑃𝑢 = ൬𝜋

4𝑃𝐿 +

2

3𝜏𝑚𝑎𝑥 − 𝑃𝑎൰ 𝐷

𝑃𝑎 = 𝐾𝑎𝜎𝑣′ − 2𝑐′√𝐾𝑎

𝜏𝑚𝑎𝑥 = 0.45√𝜎𝑐

where 𝜎𝑣′ is the effective overburden pressure at the deep depth and 𝜎𝑐 is the unconfined compressive

strength of rock mass.The lesser of those ultimate resistance values will be adopted in the analysis.

The initial slope of the P-Y curve, Ki can be determined by the following equation:

𝐾𝑖 = 𝐸𝑚 (𝐷

𝐷𝑟𝑒𝑓) 𝑒−2𝜐 ൬

𝐸𝑝𝐼𝑝

𝐸𝑚𝐷4൰

0.284

Where 𝐸𝑚 is the rock mass modulus, D is the pile diameter, 𝐸𝑝𝐼𝑝 is the bending stiffness of the pile, 𝐷𝑟𝑒𝑓

is the reference pile diameter which is equal to 0.305 m and 𝜐 is Poisson’s ratio of the pile.

The effective strength parameters of massive rock, 𝑐′ and 𝜙′ are determined using the Hoek-Brown

strength criterion as follows in the program:

∅′ = 90° − sin−1 (2𝜏

𝜎1′ − 𝜎3

′)

𝑐′ = 𝜏 − 𝜎𝑛 tan ∅′

𝜎𝑛′ = 𝜎3

′ +(𝜎1

′ − 𝜎3′)2

2(𝜎1′ − 𝜎3

′) − 0.5𝑚𝑏𝜎𝑐

𝜎1′ = 𝜎3

′ + 𝜎𝑐 (𝑚𝑏

𝜎3′

𝜎𝑐+ 𝑠)

𝑎

124


where 𝑚𝑏, 𝑠 and 𝑎 are material constants of rock and determined by the following method in PileLAT.

For GSI>25 which represents rock masses of good to reasonable quality

𝑚𝑏 = exp ൬𝐺𝑆𝐼 − 100

28൰ 𝑚𝑖

𝑠 = 𝑒𝑥𝑝 ൬𝐺𝑆𝐼 − 100

9൰

𝑎 = 0.5

For GSI<25 which represents rock masses of very poor quality

𝑚𝑏 = exp ൬𝐺𝑆𝐼 − 100

28൰ 𝑚𝑖

𝑠 = 0

𝑎 = 0.65 −𝐺𝑆𝐼

200

The required input parameters for massive rock model are shown in Figure A.11-2:





• Elastic Modulus, Em: Elastic modulus at the top of the layer top. The default value of Em is determined

by the method of Rowe and Armitage (1984): 𝐸𝑚 = 215√𝜎𝑐 (MPa) where 𝜎c is the unconfined

compressive strength of rock;

• Modulus, Rate of Change, Em-inc: It is the rock mass modulus increment rate with the layer depth from

the top of the rock layer.

• Material Constant, Mi: Intact rock constant which depends on the rock type and normally ranges from 4

to 33;

• GSI: Geological strength index;

125


Figure A.11-2 P-Y parameter input dialog for the Massive Rock in PileLAT

126


A.12 Calcareous Rock – Fragio et al. (1985)

P-Y curves for calcareous are calculated using the method by Fragio et al. (1985) and are shown in the figure

below.

Figure A.12-1 P-Y curve for calcareous rock near the ground surface

Figure A.12-2 P-Y curve for calcareous rock below the transition depth

127


Ultimate lateral resistance of calcareous rock, Pu is determined as follows:

Near the ground surface:

𝑃𝑢 = 3𝜎𝑠 (A.12-1)

Below the transition depth:

𝑃𝑢 = 9𝜎𝑠 (A.12-2)

where σs is the rock mass strength and is assumed to be 10% of the unconfined compressive strength of

rock according to the recommendation of Fragio et al. (1985). The following figure shows the variation of

strength with the depth. The transition depth is assumed to be 6 pile diameter.

Figure A.12-3 Variation of the lateral resistance with the depth

The reference displacement Yu is determined with the following equation:

𝑌𝑢 =𝑃𝑢𝐷

𝐾𝑠 (A.12-3)

𝐾𝑠 = ൬0.65

𝐷൰ (

𝐸𝑠𝐷

𝐸𝑝𝐼𝑝)

1/12

൬𝐸𝑠

1 − 𝜐2൰ (A.12-4)

where D is pile diameter, Ks is soil subgrade modulus, Es is soil’s Young’s Modulus, υ is soil’s Poisson’s

P/Pu

128


ratio and EpIp is elastic bending stiffness of pile.

The required input parameters for Fragio weak calcareous rock model as shown in Figure A.12-4:





• Elastic Modulus, Em: Elastic modulus at the top of the layer top. The default value of Em is determined

by the method of Rowe and Armitage (1984): 𝐸𝑚 = 215√𝜎𝑐 (MPa) where 𝜎c is the unconfined

compressive strength of rock;

• Modulus, Rate of Change, Em-inc: It is the rock mass modulus increment rate with the layer depth from

the top of the rock layer.

• Poisson’s Ratio, Mur, Poisson’s Ratio for the rock. The default value is 0.25 in the program.

Figure A.12-4 P-Y parameter input dialog for the Weak Rock – Fragio in PileLAT

129


A.13 Elastic-Plastic Model for soils and rocks

P-Y curve of Elastic-Plastic model for both soils and rocks is shown in the figure below:

Figure A.13-1 P-Y parameter input dialog for the Elastic-Plastic Model

Ultimate lateral resistance Pu is determined based on the material type as detailed below:

• Cohesive soils - API clay model with the provided undrained shear strength value

• Granular soils – Reese sand model with the provided effective friction angle value; and

• Rock – Weak rock (Reese) model with the provided unconfined compressive strength value and RQD of 0.

The linear portion of the P-Y curve, K is determined with the following equation:

𝐾 = ൬0.65

𝐷൰ (

𝐸𝑠𝐷4

𝐸𝑝𝐼𝑝)

1/12

൬𝐸𝑠

1 − 𝜐2൰ (A.13-1)

where D is pile diameter, K is soil subgrade modulus, Es is soil’s Young’s Modulus, υ is soil’s Poisson’s ratio

and EpIp is elastic bending stiffness of pile.

The required input parameters for Elastic-Plastic clay model in PileLAT are shown in Figure A.13-2 and




set.


input material set.

130


• Elastic Modulus: Young’s modulus of the material set.

• Elastic Modulus – Rate of Change: Increase rate of the elastic modulus from the top of the soil layer with

the input material set.

• Poisson’s Ratio: It is the Poisson’s ratio for the input material.

Figure A.13-2 P-Y parameter input dialog for the Elastic-Plastic Clay Model in PileLAT

The required input parameters for Elastic-Plastic sand model in PileLAT are shown in Figure A.13-3 and



• Effective Friction Angle: Effective friction angle of the input material set.





131


Figure A.13-3 P-Y parameter input dialog for the Elastic-Plastic Sand Model in PileLAT

The required input parameters for Elastic-Plastic rock model in PileLAT are shown in Figure A.13-4 and



• UCS: Unconfined compressive strength of rock

• UCS Strength – Rate of Change: Increase rate of the unconfined compressive strength from the top of

the soil layer with the input material set.





132


Figure A.13-4 P-Y parameter input dialog for the Elastic-Plastic Rock Model in PileLAT

133


A.14 Elastic Model for soils and rocks

Elastic model in PileLAT adopts the subgrade modulus to calculate the response of soils/rocks under the

lateral deformation.

𝐾ℎ =𝑃

𝑦 (A.14-1)

where 𝐾ℎ is the subgrade modulus with the unit of kN/m/m, 𝑃 is the force per length along the pile with

the unit of kN/m and y is the lateral displacement with the unit of m.

Note that 𝐾ℎ is different from the coefficient of subgrade modulus, 𝑘ℎ which has the unit of kN/m^3. The

relationship between the subgrade modulus 𝐾ℎ and the coefficient of subgrade modulus 𝑘ℎ can be

expressed by the following equation:

𝐾ℎ = 𝑘ℎ𝐷 (A.14-2)

where D is the pile diameter/width.

The required input parameters for Elastic Model on the advanced page of the soil layer input dialog in PileLAT

are as follows:


• Elastic Subgrade Reaction, kh: It is the coefficient of subgrade modulus at the layer top

• kh – Rate of Change: It is the increment of the coefficient of subgrade modulus with the depth from the

layer top.

134


Figure A.14-1 P-Y parameter input dialog for the Elastic Model in PileLAT

135


A.15 Calcareous Soil – Dyson and Randolph (2001)

P-Y curve for calcareous soils has a markedly different format to those for sand and clay. This unique response

was identified in centrifuge modelling undertaken in the late 1980s at Cambridge University. The p-y curve is

based on the recommendation by Dyson and Randolph (2001) and given by the following relationship:

𝑝 = 𝛾′ ∙ 𝐷 ∙ 𝑅 ∙ ൬𝑞𝑐

𝛾′ ∙ 𝐷൰

𝑛

∙ (𝑦

𝐷)

𝑚

(A.15-1)

Note that 𝛾′ is effective unit weight of the soil, D is the pile width, R is the constant for curve stiffness, 𝑞𝑐

is cone penetration resistance at the node depth, n is the empirical constant and m is the constant for p-y

curve curvature. Figure A.15-1 shows the typical p-y curve based on Dyson and Randolph (2001).

Figure A.15-1 P-Y curve for Calcareous Soil – Dyson and Randolph (2001)

The required input parameters for Calcareous Soil – Dyson and Randolph (2001) are shown in Figure A.15-2

and summarised as below:


• CPT qc: Cone penetration resistance at the top of the soil layer

• CPT qc – Rate of change: The increase rate of the cone penetration resistance with the depth from the

top of the soil layer

• Constant, R: The empirical constant for curve stiffness. A value of 2.7 usually gives good fit with the testing

results.

• Constant, n: The empirical constant for p-y curve. A value of 0.72 usually gives good fit with the testing

results.

• Constant, m: The empirical constant for the p-y curve curvature. A value of 0.58 usually gives good fir

𝑃

𝑌 0

Dyson and Randolph (2001)

136


with the testing results.

Figure A.15-2 P-Y parameter input dialog for Calcareous Soil – Dyson and Randolph (2001)

137


A.16 Calcareous Soil – Novello (1999)

P-Y curve for calcareous soils is based on the recommendation by Novello (1999) and given by the following

relationship:

𝑝

𝐷= 2 ∙ (𝛾′ ∙ 𝑧)0.33 ∙ 𝑞𝑐

0.67 ∙ (𝑦

𝐷)

0.5

(A.16-1)

Note that 𝛾′ is effective unit weight of the soil, D is the pile width, Z is the point depth below the ground

surface and 𝑞𝑐 is cone penetration resistance at the node depth. Figure A.16-1 shows the typical p-y curve

based on Novello (1999).

Figure A.16-1 P-Y curve for Calcareous Soil – Novello (1999)

The required input parameters for Calcareous Soil – Novello (1999) are shown in Figure A.16-2 and



• CPT qc: Cone penetration resistance at the top of the soil layer

• CPT qc – Rate of change: The increase rate of the cone penetration resistance with the depth from the

top of the soil layer

𝑃

𝑌 0

Novello (1999)

138


Figure A.16-2 P-Y parameter input dialog for Calcareous Soil – Novello (1999)

139


A.17 Weak Carbonate Rock – Abbs (1983)

P-Y curve for weak carbonate rock was developed by Abbs (1983) for offshore platforms in the Middle East

with carbonate rocks having unconfined compressive strength in the range from 0.5 to 5 MPa. The proposed

p-y curve consists of the following parts:

• An initial intact rock resistance curve represented by static stiff clay with water model proposed by Reese

et al. (1975) which is documented in Section A.5, and

• Residual rock frictional resistance curve calculated with using the procedures for sand (cyclic case)

proposed by Reese et al. (1974) detailed in Section A.7. Residual friction angles are used to define the

strength. The transition between the two curves occurs shapely, with an additional displacement of 10%

from the end of the intact rock response to the start of the residual friction response.

Figure A.17-1 shows the typical p-y curve for the weak carbonate rock – Abbs (1983).

Figure A.17-1 P-Y curve for Weak Carbonate Rock – Abbs (1983)

The required input parameters for Weak Carbonate Rock (Abbs, 1983) are shown in Figure A.17-2 and






• Residual Friction Angle (Deg): Residual frictional angle. Note that carbonate materials exhibit high peak

friction angles near or above 40 degree but after very few cycles of shear the values fall to a residual value

of between 24 and 33 degrees.


𝑃

𝑌 0

𝐸𝑠𝑖 = 𝐾𝑠 ∙ 𝑋

𝑃 =𝑃𝑐

2ඨ

𝑌

𝑌50

140



• Modulus Coefficient: Modulus coefficient of the soil material used to calculate the initial soil stiffness.

Figure A.17-2 P-Y parameter input dialog for Weak Carbonate Rock – Abbs (1983)

141


A.18 Cemented c-phi soil (silt) – Reese et al (1974)

P-Y curve for cemented c-phi soil (silt) is based on the recommendation by Reese et al. (1974) and given by

the following relationships:

• Initial linear section between the origin and point k with slope of 𝐾𝑠 = 𝑘𝑝𝑦 ∙ 𝑧 , where 𝑘𝑝𝑦 is the

modulus coefficient value input by the users and z is the point depth.

• Parabolic section between points k and m defined by the following relationship:

𝑝 = 𝐶 ∙ 𝑦1 𝑛Τ (A.18-1)

where n is empirical factor for curve fitting.

• Linear section between points m and u with slope m:

𝑝 = 𝑝𝑚 + 𝑚 ∙ (𝑦 − 𝑦𝑚) (A.18-2)

• Last section with the flat line beyond point u:

𝑝 = 𝑝𝑢 (A.18-3)

Figure A.18-1 shows the typical p-y curve for the cemented c-phi soil based on Reese et al. (1974).

Figure A.18-1 P-Y curve for cemented c-phi soil (silt)

The following relationships are adopted to calculate the control points along the p-y curves:

𝑃

𝑌 0

𝑃𝑚

𝑏/60 3𝑏/80

𝐾𝑠 = 𝑘𝑝𝑦𝑧

𝑝𝑘

𝑦𝑘

𝑦𝑚

𝑚

𝑃𝑢

𝑦𝑢

142


𝑦𝑘 = ൬𝐶

𝐾𝑠൰

𝑛𝑛−1

(A.18-4)

𝑦𝑚 =𝑏

60

(A.18-5)

𝑦𝑢 =3𝑏

80

(A.18-6)

𝑝𝑚 = 1.5 ∙ 𝑝∅ + 𝑝𝑐 (A.18-7)

𝑝𝑢 = �̅� ∙ 𝑝∅ (A.18-8)

𝑝∅ = 𝑚𝑖𝑛(𝑃𝑠𝑡, 𝑃𝑠𝑑) (A.18-9)

𝑃𝑠𝑡 is the ultimate resistance of sand at the shallow depths and is determined according to the following

relationship:

𝑃𝑠𝑡 = 𝛾𝑋 [𝐾0𝑋 tan 𝜑′ sin 𝛽

tan(𝛽 − 𝜑′) cos 𝛼+

tan 𝛽

tan(𝛽 − 𝜑′)(𝐷 + 𝑋 tan 𝛽 tan 𝛼)

+ 𝐾0 tan 𝛽 (tan 𝜑′ sin 𝛽 − tan 𝛼) − 𝐾𝑎𝐷]

(A.18-10)

and 𝑃𝑠𝑑 is the ultimate resistance of sand at deep depths and is determined according to:

𝑃𝑠𝑑 = 𝛾𝑋𝐷{𝐾𝑎[(tan 𝛽)8 − 1] + 𝐾0 tan 𝜑′ (tan 𝛽)4} (A.18-11)

where:


K0 = coefficient of earth pressure at rest

φ′ = angle of internal friction of sand

β = 45° +φ′

2

α = φ′

2

Ka = [tan (45° −φ′

2)]

2

143


D = pile diameter

The required input parameters for Cemented c-phi soil (silt) are shown in Figure A.18-2 and summarised as

below:




• Modulus Coefficient: Modulus coefficient of the soil material used to calculate the initial soil stiffness.

Figure A.18-2 P-Y parameter input dialog for Cemented c-phi Soil (Reese et al. 1974)

144


A.19 User-defined P-Y model

User-defined p-y curve can be input but the users and Figure A.19-1 shows the input dialog for user-defined

p-y curves. The total unit weight needs to be input mainly for the calculation of the total and effective vertical

stress within the soil layers. For multiple soil layers, effective vertical stress is an important factor for

estimating the p-y curves for other p-y models.

Figure A.19-1 User-define P-Y model input in PileLAT

Clicking the button of “Open User p-y Curves” as shown in Figure A.19-1 opens a new dialog for the input of

user-defined p-y curve data as shown in Figure A.19-2. The required input parameters for user-defined p-y

curve data are summarised as below:


• Ultimate Lateral Resistance at the layer top: It is the ultimate lateral resistance at the layer top.

• Change Rate of Ultimate Lateral Resistance: Increase rate of the ultimate lateral resistance from the top

of the input soil layer. Therefore, the ultimate lateral resistance at any depth within the input soil layer is

calculated based on the ultimate lateral resistance at the layer top and the rate of change of the ultimate

lateral resistance with the depth from the top of the input soil layer.

• y/D: The ratio of the input y displacement to the pile diameter.

145


• P/Pu: The ratio of the input lateral resistance to the ultimate lateral resistance.

Figure A.19-2 Input of user-defined p-y curves data in PileLAT

Clicking “Add” or ‘Delete” button will add or delete the selected user-defined p-y curve data point. Clicking

“Plot” button will update the p-y curve plot on the right graphical area.

146


Appendix B. Fleming’s method for pile settlement analysis

The method proposed by Fleming (1992) is based on the hyperbolic relationship assumptions for both shaft

and base load displacement responses. Elastic shortening of the pile is considered separately.

The relationship between the pile displacement ∆𝑠 and shaft load 𝑃𝑠 is:

∆𝑠=𝑀𝑠𝐷𝑠𝑃𝑠

𝑈𝑠 − 𝑃𝑠

where 𝐷𝑠 is the pile diameter, 𝑃𝑠 is the shaft load, 𝑈𝑠 is the ultimate total shaft resistance and 𝑀𝑠 is

the dimensionless flexibility factor ranging from 0.0001 to 0.004. Fleming (1992) suggested the value of

approximately 0.0005 for soft rocks.

The hyperbolic relationship between the pile toe displacement ∆B and pile base load PB is:

∆𝐵=0.6𝑈𝐵𝑃𝐵

𝐷𝐵𝐸𝐵(𝑈𝐵 − 𝑃𝐵)

where 𝐷𝐵 is the pile diameter at the base, 𝑃𝐵 is the pile toe load, 𝑈𝐵 is the ultimate pile toe bearing

resistance force and 𝐸𝐵 is the Young’s Modulus of the material at the pile toe. The total load at the pile

head, 𝑃𝑇 is calculated as:

𝑃𝑇 = 𝑃𝐵 + 𝑃𝑆

The elastic shortening ∆𝐸 of the pile is determined with using the following equation to the load up to the

ultimate shaft load, 𝑈𝑆:

∆𝐸=4

𝜋

𝑃𝑇(𝐿0 + 𝐾𝐸𝐿𝐹)

𝐷𝑆2𝐸𝐶

For the greater load, the following equation is used to calculate the elastic shortening:

∆𝐸=4

𝜋

1

𝐷𝑆2𝐸𝐶

[𝑃𝑇(𝐿0 + 𝐿𝐹) − 𝐿𝐹𝑈𝑆(1 − 𝐾𝐸)]

where 𝐸𝐶 is the Young’s modulus of the pile material, 𝐿0 is pile free length where no friction resistance

from the soils, 𝐿𝐹 is length of the pile with friction load transfer and 𝐾𝐸 is effective length coefficient

ranging from 0.4 to 0.5.

147


Figure B-1 Parameter input dialog for Fleming (1992)’s method

In the program, the parameter input for Fleming (1992)’s method is very straightforward. Only three

parameters are required to be provided in the input dialog as shown in Figure B-1. The default

dimensionless flexibility factor is 0.01. The default effective length coefficient is 0.65. The default elastic soil

stiffness under the pile toe position is 50000 kPa.

148


Appendix C. Examples

149


C.1 Example 1 - Steel pipe pile driven into soft clay and sand layers

This example involves a single 600 mm diameter steel pipe pile of 25 m long driven through soft clay (15 m

thick) and into the medium dense sand. The soft clay layer is 5 m below the water surface. The wall thickness

of the steel pipe pile is 20 mm. The undrained shear strength of the soft clay is 35 kPa at the layer top and

increases in the rate of 1 kPa/m along the depth. The effective friction angle of medium dense sand is 35

degree.

Figure C.1-1 Ground profile with the pile length and loading conditions for Example 1

Forces applied at the pile head are (1) axial force of 500 kN and (2) lateral force of 350 kN. The bending

moment applied at the pile head is 0 in this example. Figure C.1-1 shows the ground profile with the pile

length and loading conditions for this example.

Note that the cantilever portion of the pile is modelled with using a layer with “Null” material type in PileLAT

program. If the cantilever portion is within the water such as driven piles used for offshore projects, the user

only needs to make sure that this special “Null” layer is under water table in the soil layer input. In this

example, since the first 5 m cantilever portion is within the water, the first layer – which is the layer with

“Null” material type under the water table. The water table is shown as a thicker blue line in the ground

profile as shown in Figure C-1. The analysis results (deflection, bending moment, shear force and soil reaction)

are shown in Figure C.1-2.

150



Figure C.1-3 Analysis results along the pile with the static load

151


Figure C.1-4 Analysis results along the pile with the static load

152


C.2 Example 2 - Steel pipe pile driven into soft clay and sand layers with cyclic loading

All the other inputs are the same as Example 1 except for that cyclic load with 2000 cycles is adopted instead

of the static loads at the pile top. Figure C.2-1 shows the cyclic load setting for the applied force at the pile

head. Figure C.2-2 shows the distribution of lateral displacement along the pile for this example.

Figure C.2-1 Cyclic load setting for the applied force at the pile head

153


Figure C.2-2 Lateral displacement along the pile with the cyclic load

Figure C.2-3 Cyclic Matlock soft clay p-y curves at the selected nodes

154


C.3 Example 3 - Steel pipe pile driven into soft clay and sand layers with sloping ground surface

All the other inputs are the same as Example 1 except for that sloping ground surface is adopted in this

example. The surface angle is 15 degree. Figure C.3-1 shows the input of the sloping ground surface for this

example. Figure C.3-2 shows the distribution of lateral displacement along the pile for this example.

Figure C.3-1 Sloping ground surface (15 degree)

155


Figure C.3-2 Lateral displacement along the pile for the sloping ground surface

156


C.4 Example 4 – Bored pile socketed into rock layers

This example involves a 600 mm diameter reinforced concrete bored pile installed through multiple sand and

clay layers and socketed into strong rock by 4 m. The pile length is 20 m and the ground water table is about

4.5 m below the ground surface. The ground profile is shown in the table below.

Table C.4-1 Ground profile information for Example 4

Layer

No Layer Name

Layer

Thickness

(m)

P-Y Model

1 Medium dense to dense sand layer 2 API Sand

2 Stiff clay layer 2.5 Stiff clay without free

water (Reese)

3 Soft clay layer 5.0 Soft Clay – Matlock

4 Stiff clay layer 2.0 Stiff Clay with Free Water

(Reese)

5 Dense sand Layer 2.0 Reese Sand

6 Very low to low strength rock 2.5 Weak Rock (Reese)

7 Medium to high strength rock 4.0 Strong Rock

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Detailed soil layer input parameters are shown in the table below.

Table C.4-2 Summarised soil strength parameters for Example 4

Layer No

Strength Parameters

Undrained Shear

Strength, 𝒔𝒖 (kPa)

Effective Friction

Angle, 𝝓′ (deg)

Unconfined

Compressive

Strength, UCS (MPa)

1 - 36 -

2* 95 - -

3 25 - -

4 100 - -

5 - 40 -

6 - - 1.0

7 - - 10.0

* Undrained shear strength increment rate is 0.5 kPa/m from the layer top for this soil layer.

Both static axial force and lateral force are applied at the pile head. The applied axial force is 500 kN in

compression and the applied lateral force is 500 kN. The bending moment applied at the pile head is 0 in this

example. Figure C.4-1 shows the ground profile with the pile length and loading conditions for this example.

The detailed input p-y curve parameters are shown in Figure C.4-2 from the tree view area of the program.

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Figure C.4-2 Input p-y curve parameters for Example 4

The detailed analysis results under the applied loading are shown in Figure C.4-3. The comparison results

between PileLAT and RSPile for this example are shown in Figure C.4-4 and Figure C.4-5.

159


Figure C.4-3 Detailed analysis results along the pile for Example 4

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C.5 Example 5 – Driven Steel Pipe Piles under Distributed Displacement Loads along the Pile

This example demonstrates the use of US Units and how the lateral spreading is modelled in PileLAT program

through distributed load option. This example involves a steel pipe pile with 48-inch diameter and 1-inch

thickness, which is driven into clay and sand layers. The pile length is 50 ft and the ground water table is

about 4 ft below the ground surface. The ground profile is shown in the table below.


Layer

No Layer Name

Layer

Thickness

(ft)

P-Y Model

1 Stiff Clay Layer 4 Stiff clay without free

water (Reese)

2 Sand Layer 10 Liquefied Sand

3 Stiff Clay Layer 50 Stiff clay with free water

(Reese)

Detailed soil layer input parameters are shown in the table below.

Table C.5-2 Summarised soil strength parameters for Example 5

Layer No

Strength Parameters

Undrained Shear

Strength, 𝒔𝒖 (lbs/ft2)

Effective Friction

Angle, 𝝓′ (deg)

Unit Weight

(lbs/ft3)

1 1650 - 115

2* - - 110

3 1800 - 120

* Undrained shear strength increment rate is 35.3 pcf from the layer top for this soil layer.

Static lateral force is applied at the pile head. The applied lateral force at the pile head is 5000 lbf. The bending

moment applied at the pile head is 0 in this example. The lateral spreading is modelled with distributed lateral

displacement in this example. In PileLAT, the users can input the lateral displacement (lateral spreading) at

the node point along the pile length.

Figure C.5-1 shows the values of the applied lateral displacement at the node point – 10 inch (0.8333 ft)

lateral displacement from Node 1 to 95 ( 14 ft below the ground surface). This is to model the lateral

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spreading within the top stiff clay and liquefied sand layers.

Figure C.5-1 Distributed Lateral Loading Input for Example 5

Figure C.5-2 Distributed Lateral Loading Input for Example 5

Figure C.5-2 shows the input parameters at the tree view area of the program. Figure C.5-3 shows the graphic

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display of the input distributed lateral displacement along the pile. Figure C.5-4 shows the analysis results of

the pile under lateral loading. Figure C.5-5 shows the p-y curves for the selected nodes No 2 (stiff clay without

water) and No 12 (liquefied sand).

Figure C.5-3 Graphic plot of the distributed displacement along the pile

Figure C.5-4 Graphic plot of the analysis results

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Figure C.5-5 Graphic plot of the p-y curves for Nodes 2 and 12

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C.6 Example 6 – Pile under Lateral Loading in Soil Layer of Elastic Subgrade Model

This example mainly validates the solutions from PileLAT program by comparing with the lateral displacement

results from the theoretical equations as given by Hetenyi (1946) as cited in Poulos and Davis (1980).

𝛿 =2𝑃𝐻𝜆

𝐾ℎ𝑏× [

sinh 𝜆𝐿 cos 𝜆𝑍 cosh 𝜆(𝐿 − 𝑧) − sin 𝜆𝐿 cosh 𝜆𝑧 cos 𝜆(𝐿 − 𝑧)

(sinh 𝜆𝐿)2 − (sin 𝜆𝐿)2]

where

𝜆 = (𝐾ℎ𝑏

4𝐸𝑝𝐼𝑝)

1/4

Note that L is the pile length, z is the depth below the pile head, b is the pile diameter, 𝐾ℎ is the subgrade

modulus, 𝐸𝑝𝐼𝑝 is the bending stiffness of pile and 𝑃𝐻 is the lateral loading applied at the pile head.

This example involves a steel pipe pile with 12-inch external diameter and 11-inch internal diameter into the

homogeneous soil layer modelled by the elastic subgrade model. The pile length is 50 ft and the soil layer is

dry. The ground profile adopted in the analysis is shown in the table below. Figure C.6-1 shows the ground

profile and loading conditions for this example.


Layer

No Layer Name

Layer

Thickness

(ft)

Elastic Subgrade

Modulus

(lbf/ft3)

P-Y Model

1 Elastic soil layer 60 864000 Elastic subgrade

Static lateral load of 1000 kips is applied at the pile head. The boundary condition at the pile head is free pile

head. Figure C.6-2 shows the analysis results of the pile under lateral loading as output from PileLAT program.

Comparison results between PileLAT and Hetenyi’s closed-form equations are shown in Figure C.6-3.

The results from two separate runs with different element numbers (30 elements and 100 elements over 50

ft long pile) based on PileLAT are plotted against the results from the closed-form equations. PileLAT program

essentially predicts exactly the same results as Hetenyi’s closed-form equations, and the results are not

sensitive to the number of elements adopted in the analysis.

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Figure C.6-2 Detailed analysis results along the pile for Example 6

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Figure C.6-3 Comparison results between Hetenyi’s Solution and PileLAT

0

5

10

15

20

25

30

35

40

45

50

-1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

Dep

th (

ft)

Deflection (inch)

Hetenyi's Solution (1946)

PileLAT (100 elements)

PileLAT (30 elements)

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REFERENCES

American Petroleum Institute, (2000). Recommended Practice for Planning, Designing and Constructing

Fixed Offshore Platforms – Working Stress Design, API RP 2A-WSD, 21st Edition, Errata and Supplement,

October, 2007.

Baquelin, F. (1982). Rules for the structural design of foundations based on the selfboring pressuremeter

test. Proceeding of the symposium on the pressuremeter and its marine application. Paris,: IFP; 347-362.

Brown, D. A., (2002). Personal Communication about “Specifying Initial k for Stiff Clay with No Free Water.”

Fragio, A. G., Santiago, J. L., and Sutton, V. J. R. (1985) Load Tests on Grouted Piles in Rock, Proceedings 17th

Annual Offshore Technology Conference, Houston, OTC 4851, 93-104.

Hetenyi, M. (1946). Beams on elastic foundations. Ann Arbor, Michigan: Univ. of Mich. Press.

Kulhawy, F. H., Prakoso, W. A., and Akbas, S. O. (2005) Evaluation of Capacity of Rock Foundation Sockets.

The 40th U.S. Symposium on Rock Mechanics (USRMS): Rock Mechanics for Energy, Mineral and

Infrastructure Development in the Northern Regions in Anchorage, Alaska.

Liang, R., Yang. K., and Nusairat, J. (2009). “p-y Criterion for Rock Mass,” Journal of Geotechnical and

Geoenvironmental Engineering, Vol. 135, No. 1, pp. 26-36.

Matlock, H., (1970). “Correlations for Design of Laterally Loaded Piles in Soft Clay,” Proceedings, 2nd

Offshore Technology Conference, Vol. 1, pp. 577-594.

O’Neill, M. W., and Hassan, K. M. (1994). Drilled Shafts: Effects of construction on performance and design

criteria. Proc., Int. Conf. on Des. And Constr. Of Deep Found., Vol 1, Federal Highway Administration,

Orlando, Fla., 137 – 187.

O'Neill, M.W., and Reese, L.C. (1999). "Drilled Shafts: Construction Procedures and Design Methods,"

Publication No. FHWA-IF-99-025, Federal Highway Administration, Washington, D.C.

Pells, P. J. N. (1999). State of Practice for the Design of Socketed Piles in Rock, Proceedings, 8th Australia

New Zealand Conference on Geomechanics, HoBart.

Pouloa, H.G. & Davis E.H. (1980). Pile foundation analysis and design. New York: Wiley.

Reese, L. C., (1997). “Analysis of Piles in Weak Rock,” Journal of the Geotechnical and Geoenvironmental

Engineering Division, ASCE, pp. 1010-1017.

Reese, L. C., Cox, W. R., and Koop, F. D. (1974). “Analysis of Lateral Loading Piles in Sand,” Proceedings, 6th

Offshore Technology Conference, Vol. 2, pp. 473-484.

Reese, J. C.. and Van Impe, W. F. (2001). Single piles and pile groups under lateral loadings. A. A. Balkema,

Rotterdam

Rollins, K. M., Gerber, T. M., Lane, J. D., and Ashford, S. A. (2005a). “Lateral Resistance of a Full-Scale Pile

Group in Liquefied Sand,” Journal of the Geotechnical and Geoenvironmental Engineering Division, ASCE,

Vol. 131, pp. 115-125.

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Rollins, K. M., Hales, L. J., and Ashford, S. A. (2005b). “p-y Curves for Large Diameter Shafts in Liquefied

Sands from Blast Liquefaction Tests,” Seismic Performance and Simulation of Pile F7oundations in Liquefied

and Laterally Spreading Ground, Geotechnical Special Publication No. 145, ASCE, pp. 351-376.

Rowe, R. K., and Armitage, H. H., (1987). A design method for drilled piers in soft rock. Canadian

Geotechnical Journal, 24, 126-142.

Welch, R. C., and Reese, L. C.,(1972). “Laterally Load Behavior of Drilled Shafts,” Research Report No. 3-5-

65-89, Center for Highway Research, the Universityof Texas at Austin, May 1972.

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User Manual for PileLAT (Version 2.3)

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