Post-cyclic shear behavior of reconstituted marine silty clay with different degrees of reconsolidation

Abstract

In this paper, a series of dynamic triaxial tests have been carried out to study the post-cyclic shear behavior of the reconstituted marine silty clay. Most previous studies on the post-cyclic shear characteristics of clay considered no reconsolidation after cyclic loading, and a few studies investigated the influence of full reconsolidation. The actual marine clay after cyclic loading tends to be in a state between no reconsolidation and full reconsolidation after cycling. Therefore, different reconsolidation processes including no reconsolidation, full reconsolidation and different degrees of reconsolidation were conducted to investigate their effects on the post-cyclic shear characteristics. Various factors including confining pressure, initial consolidated deviator stress ratio, cyclic stress ratio and degree of reconsolidation were taken into account. Results show that the post-cyclic shear strength will be enhanced and weakened with the full and no reconsolidation, respectively. And a specific degree of reconsolidation is existed for the specimens, with which the post-cyclic shear strength equals to the corresponding static shear strength. During the post-cyclic monotonic shear process, the silty clay always have a positive pore pressure and show dilative tendency. Moreover, no significant effects of cyclic loading and reconsolidation history on the change of critical stress ratio in p′-q plane was observed for the reconstituted silty clay. The critical stress line for specimens in e-log p′ plane tends to be affected by the previous cyclic loading amplitude, irrespective of the reconsolidation process. Besides, a post-cyclic shear strength model which can consider different degrees of reconsolidation was obtained based on the Yasuhara equivalent overconsolidation model. The predicted results demonstrate a good agreement with the measured one.