Development of an ACIP Pile-Specific Load-Displacement Model

176 Pages·2013·4.47 MB·English

by  Adami, Nasim

AN ABSTRACT OF THE THESIS OF

Nasim Adami for the degree of Master of Science in Civil Engineering presented
on October 28, 2013.

Title: Development of an ACIP Pile-Specific Load-Displacement Model.

Abstract approved:

_________________________________________________________________
Armin W. Stuedlein

Augered cast-in-place piles, also known as ACIP piles, have been used for more than
seven decades in the United States and have gained in popularity due to their relatively
quick installation and cost-effectiveness. Owing to the reduced impact on the neighboring
environment as compared to some other deep foundation installation methods, ACIP piles
are appropriate for use in urban areas. Although there has been an increase in application
of ACIP piles, relatively little research on this type of pile has been performed as
compared to similar deep foundations, such as drilled shafts. The insufficient
experimental work on ACIP pile behavior and lack of ACIP pile specific load-
displacement models have led practicing engineers to use the results and methodologies
from drilled shafts. An example of this is the use of t-z and q-z based load transfer models
from drilled shaft-specific relationships to estimate the load-displacement behavior of
ACIP piles. Such applications can result in an underestimation of shaft resistance and
consequently disagreement between the predicted and measured load-displacement
behavior of the ACIP piles.
This thesis evaluates the ability of currently used load-displacement models to
estimate the measured load-displacement behavior of ACIP piles. Also, a new
empirically-based ACIP pile-specific t-z model is proposed that, in combination with the
O’Neill and Reese (1999) q-z model and ACIP pile-specific toe bearing resistance model,
forms an ACIP pile specific load-displacement model. Experiments of instrumented
ACIP piles installed in the granular soils of Western Washington were used to develop
the ACIP pile specific t-z model. Comparison between the results from the currently used
load-displacement models with the proposed model showed that the proposed model
provides an improvement in the prediction of the load-displacement behavior of ACIP
piles.
Finally, an analysis of variability is performed using the Monte Carlo Simulation
with the sample probability distributions of the uncertain variables in load-displacement
model. These analyses result in provide a set of possible loads for a number of common
service level displacements, which are reported as cumulative density function (CDF)
curves. The CDF curves for loads corresponding to a displacement considered can be a
useful tool in design procedure of ACIP piles.
©Copyright by Nasim Adami
October 28, 2013
All Rights Reserved
Development of an ACIP Pile-Specific Load-Displacement Model

by
Nasim Adami

A THESIS

submitted to

Oregon State University

in partial fulfillment of
the requirements for the
degree of

Master of Science

Presented October 28, 2013
Commencement June 2014
Master of Science thesis of Nasim Adami presented on October 28, 2013.

APPROVED:

Major Professor, representing Civil Engineering

Head of the School of Civil and Construction Engineering

Dean of the Graduate School

I understand that my thesis will become part of the permanent collection of
Oregon State University libraries. My signature below authorizes release of my
thesis to any reader upon request.

Nasim Adami, Author
ACKNOWLEDGEMENTS

I would like to express my very great appreciation to my major advisor Dr.
Armin Stuedlein for his guidance along this research and providing an
environment for me to realize my abilities. I also want to thank my graduate
committee members, Dr. Sessions, Dr. Mason, and Dr. Leshchinsky for their
helpful suggestions.
I would like to offer my special thanks to faculty and staff of the Oregon State
University School of Civil and Construction Engineering for their dedication and
support. Finally, I am particularly grateful for the support given by all my friends
and graduate students of Geotechnical Engineering.
TABLE OF CONTENTS
Page
1 Introduction .................................................................................................................... 1
1.1 Problem Statement .................................................................................................. 1
1.2 Research Outline ..................................................................................................... 1
2 Literature Review ........................................................................................................... 3
2.1 Introduction ............................................................................................................. 3
2.1.1 Drilled Shaft Foundations ................................................................................. 5
2.1.2 Augered Cast-in-Place Piles ............................................................................. 5
2.2 Bearing Capacity of Drilled Deep Foundations ...................................................... 7
2.2.1 Estimation of Bearing Capacity of Drilled Shaft Foundations ..........................
in Granular Soils ............................................................................................... 8
2.2.2 Estimation of Bearing Capacity of Augered Cast-in-Place Piles .................... 16
2.3 Prediction Models of Pile Settlement in Granular Soils ........................................ 21
2.3.1 Vesic (1977) Settlement Method .................................................................... 21
2.3.2 Introduction to t-z and q-z Models .................................................................. 24
2.4 Summary ............................................................................................................... 34
3 Research Objectives ..................................................................................................... 35
4 Database of Loading Test Cases .................................................................................. 37
4.1 Static Pile Load Test Data for 1997 Test Series .................................................... 37
4.1.1 General ............................................................................................................ 37
TABLE OF CONTENTS (Continued)
Page
4.1.2 Development of Soil Profile and Soil Parameters for the 1997 Test Series ... 40
4.2 Load Transfer and Static Load Test Results for 2009 Test Series ........................ 45
4.2.1 General ............................................................................................................ 45
4.2.2 Development of Soil Profiles and Soil Parameters for the 2009 Test Series .. 46
4.2.3 Description of the instrumentation of Piles in 2009 Test Series ..................... 51
4.2.4 Determination of Composite Modulus ............................................................ 51
4.2.5 Load Transfer .................................................................................................. 53
4.3 Summary ............................................................................................................... 57
5 Development of a Load Transfer Model for Augered Cast-in Place Piles ................... 58
5.1 Introduction ........................................................................................................... 58
5.2 Development of the t-z Model ............................................................................... 58
5.2.1 Calculation of Pile Shear Stress, t ................................................................... 59
5.2.2 Calculation the Relative Soil-Pile Movement, z ............................................. 61
5.2.3 Normalizing Parameters .................................................................................. 63
5.2.4 Proposed t-z Model Parameters....................................................................... 64
5.3 Selected q-z Model ................................................................................................ 72
5.4 Evaluation of the Proposed Load-Transfer Model ................................................72
5.5 Comparison of Results to 2009 and 1997 Test Series ........................................... 74
5.6 Summary ............................................................................................................... 87
TABLE OF CONTENTS (Continued)
Page
6 Analysis of the Proposed t-z Model by Use of Monte Carlo Simulations ................... 88
6.1 Introduction ........................................................................................................... 88
6.2 Monte Carlo Simulation in Geotechnical Engineering ......................................... 89
6.3 Input Variables and Probability Distribution of Uncertain Parameters ................. 91
6.3.1 Uncertain Variables of the Proposed Prediction Model .................................. 91
6.3.2 Probability Distribution of Uncertain Variables ............................................. 92
6.3.3 Monte Carlo Simulation of Random Variables ............................................... 97
6.4 Monte Carlo Simulation Correction .................................................................... 101
6.5 Discussion of the Results .................................................................................... 108
6.6 Summary ............................................................................................................. 112
7 Summary and Conclusion .......................................................................................... 113
7.1 Summary ............................................................................................................. 113
7.2 Conclusions ......................................................................................................... 115
7.3 Suggestions for Future Study .............................................................................. 117
References ....................................................................................................................... 118
TABLE OF CONTENTS (Continued)
Page
APPENDICES ................................................................................................................ 127
Appendix A: MATLAB® Code for Generating the Random Variables ..................... 128
Appendix B: MATLAB® Code for Calculating the Load-Displacement Response
of ACIP Piles Using t-z and q-z Models ..................................................................... 131
Appendix C: Comparison of Deterministic Coefficients Results with Results from
Random Variable Generation...................................................................................... 135
Appendix D: Detailed Monte Carlo Simulation Results ............................................. 147