Analysis on the Mechanical Behaviors of Soil-rock Mixtures Using Discrete Element Method

Two-dimensional numerical direct shear tests were carried out using the Discrete Element Method (DEM) to study the effects of rock content on the mechanical behaviors of soil-rock mixtures (SRM).The mixtures were made from particles of contrasting size and stiffness. The DEM simulation captured the behaviors of SRM as observed in previous experiments, showing that the peak shear stress and the dilation increased with an increasing rock content. Moreover, it also found that the peak friction angle and dilation angle increased while cohesion decreased with an increasing rock content. On the other hand, the DEM provided insight to the distribution of contact force chains, the magnitude and orientation of the principal stresses, and the rotation of particles experience as the shearing progressed which could not be revealed in the physical experiments. The results indicated that the rock content also had a meaningful effect on these micromechanical observations. At last, how the rock content influenced the shear strength of SRM was discussed according to Taylor's theory. It was concluded that the shear strength of SRM increased for higher rock content mainly because of the contribution of the interlocking, while the contribution of the contact friction was demonstrated to be very small.