Refined simulation for macro-and meso-mechanical properties and failure mechanism of soil-rock mixture by 3D DEM

To precisely simulate the macro and meso mechanical properties and the failure mechanism of soil-rock mixture(SRM),an improvement on the three-dimensional discrete element(3D DEM) modeling for the flexible membrane boundary method used in the triaxial tests is made with 3D wall-arrangement method. 3D DEM models of SRM to simulate the large-scale triaxial specimens are constructed using the previously developed 3D DEM modeling method for rock blocks and SRM with irregular shapes. The meso-mechanical parameters of numerical SRM specimens are calibrated by large-scale numerical triaxial tests and verified through comparison with laboratory results. The insight into the macro and meso mechanical properties and failure mechanism of SRM are obtained from the detailed simulation of large-scale triaxial tests. The results show that the proposed modeling method for 3D flexible membrane boundary has many advantages, such as fewer parameters,easy to implement and better results. The stress-strain characteristics,strength properties and failure modes of SRM are reproduced nicely with the numerical simulation of large-scale triaxial tests using the generated DEM models. With the increasing of rock block proportion,the skeleton-effect of rock blocks on numerical SRM specimens becomes more and more obvious. The particle rotations of soil matrix are larger while the particle rotations of rock blocks are generally smaller,indicating that the shear planes propagate bypassing the larger rock blocks. © 2018, Science Press. All right reserved.