Dynamic modeling of block-in-matrix rock (bimrock) focusing on tensile behavior based on the modified 2D DDA-SPH method

In recent decades, numerous geotechnical hazards, including landslides, foundation settlements, and tunnel collapses, have been linked to block-in-matrix rock (bimrock), resulting in substantial damage. The investigation and analysis of the engineering properties and mechanical behavior of both the rock and soil have become increasingly intriguing research areas. However, analyzing bimrock remains a formidable challenge due to its inherent heterogeneity. In this study, to investigate the tensile behavior of the bimrock, the numerical method that couples discontinuous deformation analysis (DDA) and smoothed particle hydrodynamics (SPH) is improved. First, a tension damage model is implemented in SPH for simulating the tensile behavior of the soil. The effectiveness of the presented model is verified through the direct tensile test model and the Brazil disc split model as an indirect tensile test. The contact algorithm of DDA-SPH is then modified by adding a tensile contact spring to introduce tensile strength at the interface between the matrix and the rock in the bimrock. Through a simple pulling numerical model, the accuracy of this modification has been verified, and the appropriate tensile contact stiffness is discussed. Furthermore, using the proposed method, the overall tensile strength of the bimrock with respect to the interface tensile strength is investigated. Finally, the proposed numerical method is applied to the simulation of geoengineering problems, demonstrating the capacity to analyze the stability and large deformation of bimrocks.