Factors Affecting Post-cyclic Undrained Shear Strength of Marine Clay

Post-cyclic undrained shear strength is primarily controlled by the cyclic loading parameters and loading conditions. In the present paper, series of undrained constant strain cyclic triaxial test followed by strain-controlled monotonic shearing was carried out on normally consolidated marine clay specimens. An attempt was made to study the variation of post-cyclic undrained shear strength with the cyclic loading conditions namely staged cyclic loading and continuous cyclic loading. The effect of cyclic loading parameters such as cyclic strain amplitude, cyclic loading frequency and drainage after the undrained cyclic loading on post-cyclic strength and stiffness is also presented. It is observed from test results that the post-cyclic undrained strength and stiffness of the specimen is greatly influenced by the cyclic loading condition and drainage after cyclic loading. It was noted that due to the multiple stages of cyclic loading followed by pore pressure dissipation, the induced apparent overconsolidation ratio is higher for staged cyclic loading than the continuous cyclic loading conditions.