An anisotropic shear strength model for cyclic accumulated plastic strain of overconsolidated clay

Abstract

Many geotechnical problems involve calculation of the permanent deformation of overconsolidated clay under undrained cyclic loading. There are many existing methods in the literature which have been made for predicting cumulative plastic deformation for soils under cyclic loading. This paper presents the development of an anisotropic shear strength model for undrained cyclic accumulated plastic strain of overconsolidated clay. Effects of cyclic stress ratio, average stress ratio and number of stress cycles are considered in the model. In addition, the model also differentiate the cyclic behaviour of clay between active (A) and passive (P) modes of loading. Test data obtained from a series of NGI cyclic triaxial tests are employed to verify the model. Comparisons between predicted and experimental results show the validity and good applicability of the anisotropic model. For general 3D stress conditions the model is extended into a modified Tresca formulation which can be implemented into finite element codes for the prediction of permanent deformation of offshore foundation under cyclic loading.