pile tutorial manual

Oasys Pile

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Printed: November 2013

Contents

1. Introduction p1

2. Pile Analysis Methods p2

3. Pile User Interface p3

4. Pile Capacity Analysis p4

5. Pile Settlement Analysis p18

p1 Section 1. Introduction

1. Introduction

Pile is a program which calculates the vertical load carrying capacities and vertical settlements of a

range of individual piles in a layered soil deposit. The theory is based on both conventional and new

methods for drained (frictional) and undrained (cohesive) soils. Settlements are calculated for solid

circular sections without under-ream.

Pile capacities may be calculated for a range of pile lengths and a range of cross-section types such

as circular, square and H-section. The circular and square cross-sections may be hollow or solid,

whereas the H-section is only solid. Under-reams or enlarged bases may be specified.

Pile settlements may be calculated for a range of pile lengths and a range of solid circular cross-

sections without under-ream.

There are two approaches available to calculate the capacity of the pile - working load approach and

limit-state approach.

The calculation itself is based on verified and robust numerical methods. The simplicity of calculation

enables new users to set up and run a pile analysis problem within hours of training.

The tutorial examples deal with a simple pile analysis, but this Tutorial Manual is intended to

familiarise the user with Pile. The examples should therefore not be used as a basis for practical

projects.

Users are expected to have an understanding of soil mechanics and geotechnical theory, and should

be able to work in a Windows environment. The tutorial lessons are also available in the examples

folder and can be used to check you results.

It is important to realise that Pile is an advanced program analysing a complex problem and the user

must be fully aware of the various methods of analysis, requirements and limitations discussed in

the User Manual before use. The Tutorial Manual will not provide theoretical background

information on the analysis method, nor does it explain the details of various methods of analysis

available in the program. These details can be found in the User Manual for Slope. This also contains

detailed information on the available program features. Short courses are also regularly organised

and should you be interested in more hands-on experience you can contact [email protected] for

dates and program content.

p2 Section 2. Pile analysis methods

2. Pile analysis methods

Either capacity analysis, settlement analysis, or both can be performed for a range of pile lengths

and cross-sections.

The soil is specified in layers in the Soil Profiles section. Each layer is set to a material, which is

specified in the Material Properties section. The material can be drained (frictional) or undrained

(cohesive) and appropriate strength parameters are specified. Maximum values can be set for

ultimate soil/shaft friction stress and end bearing stress within each layer

Levels may be specified as depth below ground level or elevation above ordnance datum (OD).

Porewater pressures within the soil deposit can be set to hydrostatic or piezometric in the

Groundwater section..

Capacity Analysis

Pile capacities may be calculated for a range of pile lengths and a range of cross-section types such

as circular, square and H-section. The circular and square cross-sections may be hollow or solid,

whereas the H-section is only solid. Under-reams or enlarged bases may be specified.

There are two approaches available to calculate the capacity of the pile - working load approach and

limit-state approach.

Settlement Analysis

Pile settlements may be calculated for a range of pile lengths and a range of solid circular cross-

sections without under-ream.

Settlement analysis calculates the settlement of a range of piles with different lengths and cross-

sections and of the surrounding soil. Pile soil slip is modelled, together with the effects of soil heave

inducing tension, or settlement causing compression and negative skin friction.

Settlement calculation is based on theoretical analyses of the settlement of single compressible piles

which are based on linear elastic theory. The analysis uses the integral method adopted by Mattes

and Poulos, and is in the User Manual.

Limiting shaft skin friction is calculated from the material properties.

p3 Section 3. Pile User Interface

3. Pile User Interface

The principal components of the user interface are illustrated below and these will be referred to in

the tutorial manual.

(Hint: When using the Gateway, click ‘+‘ to expand an item. Double click on the item to open the

corresponding window)

Tabular Output

Graphical

Output

Table View

Gateway

Output Toolbar Slope Toolbar Standard Toolbar

p4 Section 4. Pile Capacity Analysis

4. Pile Capacity Analysis

To familiarise the user with the program, a simple capacity analysis of a CFA Pile will be covered in

this tutorial. This serves as a quick introduction to the capacity feature of the Pile program.

Objectives

• Navigate the Pile Interface

• Input Capacity Data

• Create soil stratigraphy and input material properties

• Apply water data and surcharges

• Run an analysis

• Navigate the Graphical Output

• Create simple graphs

• Export tabular outputs for further analysis

p5 Section 4.1 Creating the input

4.1 Creating the input

Once opened, create a new file by clicking the ‘New File’ icon on the top left of the program

or clicking Ctrl + N

1. Fill the Titles and Units dialog box:

(Hint: Should the user need to change the Units, they should do so at this point by double

clicking on Units in the Gateway)


2. Double click on Analysis Options in the Gateway.

Select Capacity and the following options:


3. Double click on Capacity Data in the Gateway

Select the Working Load Calculation Method and click OK

Choose the following options:

4. Double click on Pile Properties in the Gateway

Select a Solid Pile without under-ream, E = 20 000 000 kPa

Select the inputs to calculate the Pile Capacity between 5m and 35m below ground level,

calculating the values every metre

Input Pile Diameters of 600mm and 700mm.

(Hint: Move onto the next line in the input table to store the previous values inputted)


5. Double click on Material Properties in the Gateway

Define materials which make up the soil profile around the pile.

Specify Nq for Material #1 as 50.

(Hint: See the User Manual for instructions on how to set the limiting value of end bearing to

‘unlimited’.)


6. Double click on Soil Profiles in the Gateway

Define layers constituting the soil profile around the pile:

o top of Layer 1 at 8mOD

o top of Layer 2 at 0mOD

o top of Layer 3 at -25mOD

(Note: The tab at the bottom of the table shown below allows the user to enter more than

one soil profile, should they wish to compare the impact of different soil properties or

stratigraphy boundaries)


7. Double click on Groundwater in the Gateway

To define a hydrostatic pore-water distribution, just define the level of the phreatic surface.

For this example, input the two phreatic surfaces for the soil profile to compare the impact

of dewatering around the pile:

• Groundwater Profile 1: 6 mOD

• Groundwater Profile 2 : 0 mOD

(Hint: Use the tab at the bottom of the table to input two different groundwater profiles)

8. Double click on Soil Profile – Groundwater Map in the Gateway.

Assign the inputted soil profile to Groundwater Profile 1.

(Note: This feature allows the user to analyse the impact of different groundwater levels on

the soil stratigraphy in one file. Once the analysis has been run for one profile, the file can be

reanalysed to compare results)

p11 Section 4.2 Analysis and Outputs

4.2 Analysis and Outputs

Prior to analysis, check all inputs and save the file

Click on the analyse button to carry out the analysis

The solution progress window will automatically appear and the analysis will run.

4.2.1 Tabular Outputs

The program will give the user the option to view tabular inputs and outputs.

1. Select the outputs only by ticking Capacity Results:


2. The tabular outputs enable the user to look at stress profiles and specific values for the pile

as shown below:

The user can determine which limiting criterion applies to different lengths of pile by using

the key provided in the Tabular Output:


Exporting Tabular Results

1. Select File > Export Results

Save the file as Tutorial 1 Exercise 1.csv to export the results to Excel


4.2.2 Graphical Outputs

1. Double click on Graphical Output in the Output section of the Gateway

2. Using the excerpt from the manual shown below, plot the ultimate and design capacities for

the pile and determine the length of pile required to support a load of 1000kN.


3. The graphical output is shown below:

4. Compare the results for a 600mm and 700mm diameter pile

5. Re-run the analysis to view the impact of the other groundwater profile (phreatic surface at

0mOD) to the pile capacity


Printing Graphical Outputs

1. Go to Tools > Preferences in the menu bar

Select appropriate options for the print output, including company information and logos.

2. Select File > Print Preview in the menu bar to check the output for printing

(Note: The user can also print the tabular output in this format)

p18 Section 5. Pile Settlement Analysis

5. Pile Settlement Analysis

To familiarise the user with the program, a simple settlement of a CFA Pile will be covered in this

tutorial. This serves as a quick introduction to the settlement feature of the Pile program.

Objectives

• Input Settlement Data

• Run an analysis

• Navigate the Graphical Output

• Create simple graphs

p19 Section 5.1. Creating the input

5.1. Creating the input

Once opened, create a new file by clicking the ‘New File’ icon on the top left of the program

or clicking Ctrl + N

Fill the Titles and Units dialog box, outlining the Program is carrying out a Pile Settlement

Analysis.

1. Double click on Settlement Data in the Gateway.

Input the following:

(Note: the excerpt from the manual outlines the definition for the different inputs and the

user must read these before moving on)

p20 Section 5.1. Creating the input

2. Enter the same data for the following as Section 4 (Capacity Analysis):

o Pile Properties

o Material Properties

o Soil Profile

o Groundwater Data

(Note: You can copy and paste between tables in different pile analysis files)

3. Double click on Applied loads and displacements in the Gateway Menu

Input a 1500kN load

(Question: At what loads will the pile stresses be presented in the output?)

4. Double click on Displacement Radii in the Gateway Menu

Input displacement radii at:

0.3m

1m

2m

(Question: Why has a radii of 0.3m been chosen?)


5.2 Analysis and Outputs

1. Prior to analysis, check all inputs and save the file

Click on the analyse button to carry out the analysis

The solution progress window will automatically appear and the analysis will run.

5.2.1 Tabular Outputs

The program will give the user the option to view tabular inputs and outputs.

1. Select the Settlement outputs only

5.2.1 Graphical Outputs

A number of different options are available. Use the definitions below to produce two

graphs outlined.

1. Pile displacement and Soil displacement at 0.3m for a 20m long pile with 500kN load

acting

2. Limiting shaft skin friction, shaft skin friction and pile stress for a 25m long pile with

700kN load acting


The expected outputs are shown below:

pile tutorial manual

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