Slope stability and post-failure analysis of soil-rock-mixture using the modified 2D DDA-SPH method

Soil-rock-mixture (SRM), consisting of high-strength rock blocks and low-strength soil, is widely distributed in nature. In traditional methods such as limit equilibrium methods, this geomaterial was simplified as a uniform medium without considering the influence of rocks due to its heterogeneity and complex physical and mechanical properties. A coupling method that bridges discontinuous deformation analysis (DDA) for rock simulation and smoothed particle hydrodynamics (SPH) for soil simulation is a promising tool for SRM problems. In this study, the 2D coupled DDA-SPH method is extended to the applications of stability and post-failure analysis of SRM slopes. First, the determination of the contact spring stiffness in the contact algorithm is presented and the reasonable value is discussed. Then, to eliminate the oscillations in some simulations with polygonal rock blocks inside the soil, the contact algorithm is modified by implementing a special treatment for the contact between the SPH particles and the convex vertices of DDA blocks. In addition, the criterion based on the distribution of plastic zone is used to define the critical stable state of the slope when applying the strength reduction technique for stability analysis, and its effectiveness is demonstrated. Finally, a series of numerical analyses are carried out, and through these numerical simulations, some conclusions and suggestions can be reached.