Simulation of rock failure by voronoi-based discontinuous deformation analysis
ZHANG Kaiyu1，2，XIA Kaiwen1，2，LIU Feng1，2
(1. State Key Laboratory of Hydraulic Engineering Simulation and Safety，Tianjin University，Tianjin 300350，China；2. Department of Architectural Engineering，Tianjin University，Tianjin 300350，China)
Abstract：Discontinuous Deformation Analysis(DDA) is an implicit discrete element method for simulating deformable discrete block systems. Since the meso-grain structure of rocks is similar to Voronoi polygons，this paper will study the rock failure simulation with DDA using Voronoi discretizations，and compare its performance with DDA using triangle discretizations. The influence of sub-block size on the elastic parameters of the material is studied，and the numbers of sub-blocks and contact pairs using these two discretizations are compared. By simulating the uniaxial compression test，Brazilian test，Brazilian test with an eccentric circular hole and Kalthoff- Winkler impact experiment，the influences of these two types of discretizations on rock macroscopic parameters，failure modes and crack propagation paths are analyzed. Meanwhile，in order to reduce mesh-dependence，the influence of the randomness of the discretizations on the simulation results are discussed. The results show that an overly regular discretizations will lead to an unreasonable failure pattern，while an overly random discretisations may lead to more disperse results and also worse convergence. That is to say，a proper degree of randomness is necessary for such simulations. It is also shown that DDA with Voronoi discretizations can effectively simulate the failure process of rocks，and in comparison with the triangle model，the Voronoi model leads to greater computational efficiency，higher elastic modulus，higher compression strength，higher tensile strength and more realistic compression-tensile ratio，and the crack propagation path is similar to the inter-granular fracture of the rock.
