Evaluation of borehole interface shear test simulations for cohesive soils under monotonic loading: A comparison of Mohr-Coulomb and constitutive models

The Cyclic Interface Shear Test (CIST) device was recently developed to evaluate the response of soil-structure interfaces subjected to monotonic or cyclic loading. Numerical models of the CIST have not been documented. Such simulations may be beneficial to help guide the design of experiments, interpret results, and inform the development of further experimental device modifications. In the present paper, a series of interface shear tests utilizing the CIST system on a cohesive soil under monotonic loadings were simulated using a proposed three-dimensional model in the commercial finite element analysis software ABAQUS/Standard. Comparisons of simulations with experimental results are presented for the Mohr-Coulomb and hypoplasticity models for cohesive soils. It is found that (i) the clay-based hypoplasticity model outperformed the simpler Mohr-Coulomb model in terms of predicting the interface shear stress evolution and the soil volume change and (ii) the clay-based hypoplasticity model allows for identification of trends in shear response as a function of normal confining pressures at the soil-structure interface (e.g. soil-structure interface shear zone thickness). Neither of these capabilities have previously been documented or experimentally validated for cohesive soil-structure interface simulations using clay-based hypoplasticity models.