Definition of failure in cyclic direct simple shear tests on normally consolidated kaolin clay and presentation of shear strain contour diagrams

Advanced laboratory testing is the main tool currently used to characterise soil behaviour under cyclic loading and inform offshore foundation design. Laboratory tests, such as cyclic direct simple shear tests, are used to compile contour diagrams of cyclic shear strain or pore pressure from which the effect of cyclic loading is assessed based on an accumulation procedure. In this study, a practical reference for design purposes is presented in the form of a contour diagram of maximum shear strain for normally consolidated kaolin clay under symmetrical cyclic loading. The paper also attempts to define the mode of failure of normally consolidated kaolin under cyclic loading based on a series of symmetrical and non-symmetrical cyclic direct simple shear tests and the shear strain failure criterion plotted as a failure envelope on contour diagrams.