Undrained Cyclic Simple Shear Behavior of Clay with Application to Pile Foundations Supporting Tension Leg Platforms

摘要

The objective of the study is to develop a basic understanding of the behavior of clays under combined static and cyclic loading conditions with particular application to deep water compliant offshore structures. The research attempts to identify and evaluate the effects of important factors on the behavior of clay elements subjected to the complex loading history typical of a Tension Leg Platform (TLP) foundation system in order to develop more rational and reliable methods for analyzing and predicting the behavior of pile shafts supporting such platforms. A comprehensive laboratory testing program, consisting of the samples of Boston Blue Clay. Results, presented in a normalized format to allow generalizations show that there is a unified definition of failure in undrained cyclic direct simple shear DSS mode of shearing independent of the value of the average static shear acting on the soil during undrained cyclic shearing. Moreover, for normally consolidated BBC, there is a threshold shear stress level below which failure in stress-controlled undrained cyclic DSS shearing does not occur, even after subjecting the soil to a very large number of cycles.