## LSU Historical Dissertations and Theses

1996

Dissertation

#### Degree Name

Doctor of Philosophy (PhD)

G. Wije Wathugala

#### Abstract

A general method for predicting pile setup, or the increase in the load carrying capacity of friction piles driven into saturated clay, was developed. The solution is based on the HiSS modeling approach, the strain path method, and the theory of nonlinear porous media. The ability of this method was demonstrated by predicting the field behavior of pile segment models during driving, subsequent consolidation, and load testing. Numerical simulations were performed on pile segment models because of the availability of field experimental tests necessary for verification and evaluation schemes. The method was also applied to investigate the behavior of full-scale friction piles driven into saturated clay. An HiSS constitutive interface model named $\delta\sbsp{2i}{\*}$ was developed in order to capture soil behavior under severe shear deformation at the soil-pile interface. Verification and evaluation of the model demonstrated the ability of the model to characterize soil behavior at the soil-pile interface. Simulation of pile driving was achieved by the strain path method. The simple pile approach was used for full-displacement (closed-ended) piles, while the concept of the 'ideal' open-ended pile was utilized for partial-displacement (open-ended) piles. Numerical simulations of pile driving were performed and successfully predicted the field behavior of the pile segment models during the driving. Finite element simulation of soil consolidation around the pile was conducted. During the consolidation phase, pile load tests were simulated at different time intervals. The purpose of simulating these tests was to predict the variation of pile shaft capacity with time. These simulations were conducted using full-displacement (closed-ended) as well as partial-displacement (open-ended) pile segment models. The results of the finite element analysis were consistent with the measurements in the field. Investigating the behavior of the pile during its various life stages resulted in the reasonable evaluation of pile shaft capacity. Finite element simulation of different pile load tests during soil consolidation provided quantitative measures for the variation in pile shaft capacity over time.

9780591204216

254

COinS