Hypoplastic predictions of changes in undrained shear strength during episodic loading

Abstract

Episodic loading patterns of undrained loading and consolidation are relevant to offshore foundation whole-life applications from variable metocean and operational conditions. In related finite-element simulations of foundation–soil interactions, the selected constitutive model then has to capture general trends of the soil response due to episodic loading, including changes in shear strength which affects the foundation's capacity. In this study, element test simulations using clay hypoplasticity were conducted to investigate the model's capability to capture general trends in the evolution of void ratio and undrained strength, which have been observed in direct simple shear (DSS) experiments on normally consolidated clay. Episodic loading in these DSS tests consisted of periods of undrained shear interspersed with consolidation and was applied to samples of normally consolidated kaolin clay. The clay hypoplastic constitutive model with the intergranular strain extension can be used to capture the response of normally consolidated clay subjected to episodic loading.