Cyclic Behavior of Clays in Undrained Simple Shear

Abstract

Undrained cyclic shearing of normally consolidated (NC) clays develops positive excess pore pressures and causes a reduction in effective stresses. As a result, initially cycled NC clay subjected to subsequent undrained monotonic shearing behaves as an overconsolidated clay. This observation is extended herein to form the basis of the apparent overconsolidation (AOCR) hypothesis and to develop a framework for predicting the undrained cyclic behavior of slightly overconsolidated clays from the NC behavior. In addition, the AOCR framework allows predictions of clay response due to cyclic shear with variable intensities. Comparisons of predictions with results of cyclic direct simple shear tests on Boston blue clay show generally favorable agreement.