Improving three-dimensional DEM modeling methods for irregularly shaped particles and their assembly

Based on the irregularly shaped rock blocks in soil-rock mixture (SRM) and the large-scale triaxial specimens of SRM with rock block proportion of 40% prepared indoor, this study aims at constructing three-dimensional DEM models for the irregularly shaped particles and their assembly as realistic as possible by improving the current modeling methods. To simulate the morphological characteristics of rock blocks, the controlling parameters of the proposed modeling methods for the geometric model for rock blocks and their evaluation methods are identified, and then the three-dimensional semi-real-shaped DEM models of rock blocks with identical sphericity and similar angularity are constructed. To obtain the volume of the rock block model for subsequent density optimization of rock block model and porosity calculation of particle assembly, a virtual slicing technique for three-dimensional DEM model is developed and adopted to evaluate the volume of the semi-real-shaped DEM models for rock blocks in combination with the digital image processing (DIP) technique. To efficiently build a SRM model whose relative density is consistent with the corresponding experimental specimens, a three-dimensional DEM modeling method for the large-scale triaxial specimens of SRM based on the quasi vibration and the compaction method and layered duplication method is proposed. The results show that the required sphericity and angularity can be simulated readily with fewer controlling parameters of the proposed modeling method for geometric model of rock blocks. When a rock block DEM model composed of a small number of packing spheres, a great deviation in the volume from the corresponding geometric model occurs. The numerical and experimental SRM specimens