Competition mechanism between dilation and interlocking in granular soils: DEM simulation and constitutive modeling

Interlocking refers to a kind of resistance caused by the staggered arrangement of granular materials. In geotechnical engineering, it is considered as one of the important sources of the shear strength of granular materials. Based on series of DEM simulations with varying particle shapes, the influences of interlocking on the mechanical behavior of granular soils are investigated in this paper, and the competition mechanism between dilation and interlocking in granular soils is discussed. A unified interlocking model is then proposed to characterize the influence of interlocking on mechanical response of granular sand with different densities, and a comprehensive interlocking parameter S is introduced to relate interlocking with yielding as well as dilation. Finally, a modified constitutive model is proposed considering the effect of interlocking within the framework of the bounding surface. And the predicted results using the proposed model have a good agreement with triaxial tests data for different sands with varying particle shapes.