Numerical simulations of simple shear tests : critical state and strain rate sensitivity

The aim of this work is to investigate the mechanical behaviour of granular specimens tested under simple shear conditions at different imposed shear rates. This work is part of a more extended scientific research essentially devoted to the understanding of the mechanical behaviour of granular soils involved in fast slope movements. The final objective is to conceive a constitutive relationship capable of simulating the phase transition suffered by these materials when fast landslides occur. In particular, the goal of this study is to highlight the role of strain rate in governing the response of the system under steady state conditions and to recognise a sort of threshold for the shear rate g under which a quasi-static response is obtained. . Simulations were performed using “Yade”, an open source framework discrete element numerical code. The aim is to present results of numerical shear tests on dense granular samples by critically discussing the reliability of the numerical results. Many factors have been considered: the confining pressure, the shape of grains the dimensions of the specimen, the role played by the granular temperature and so on.