A critical state three-dimensional multi-shear model for soil-structure interfaces under monotonic and cyclic loading

Abstract

In this paper, a three-dimensional(3D) multi-shear model of soil-structure interface is established by using the plasticity theory of boundary surface. State parameters are introduced to predict the interface response under different soil densities and normal stress. A constitutive equation is established following the assumption that the interface response is decomposed into macro-response and a series of directional-dependent micro-shear responses. The calculation method of plastic microshear strain is modified, a new calculation method of microscopic plastic shear modulus is introduced, and the calculation parameters are reduced. The proposed model can reasonably describe the variation of stress–strain relationship under 3D shearing conditions and predict the three-dimensional non-linear mechanical behaviour of the contact surface. The proposed model has a unified calculation formula for loose and dense interfaces under different loading conditions. The proposed model can be accurately described the dilatancy characteristics under low normal stress and shear shrinkage under high normal stress. The proposed model can simulate the cyclic response characteristics of the interface, e.g., the normal displacement increases with increasing cycle number, however, the growth rate decreases with increasing cycle number. The validity of the proposed three-dimensional multi-mechanism shear model of soil-structure interface under different boundary and loading conditions is verified by comparing the calculation results with the experimental results.