Numerical investigation of blast-induced fractures in granite: insights from a hybrid LS-DYNA and UDEC grain-based discrete element method

Abstract: The micro heterogeneities have a significant effect on the mechanical behaviour and failure mode of brittle rocks. In order to study the influence of microstructure and micro-mechanical properties on rock fracturing under blast loadings, a hybrid LS-DYNA and UDEC grain-based discrete element method (UDEC-GBM) is developed in this study. The LS-DYNA code is used to simulate the explosive detonation process, while the UDEC code focuses on the simulation of the rock fracturing process induced by the shock wave. First, the fracturing process of Barre granite under blasting is reproduced by the developed method. The fracture patterns simulated by the coupled LS-DYNA/UDEC-GBM method show a good agreement with experimental results. Then, using the coupled method, the effects of the grain size distribution, the average grain size, the mineral composition, and the contact tensile strength between minerals on the blast-induced fractures are systematically investigated. Numerical results show that intergranular tensile cracks dominate the rock fracturing under blast loadings. The number of microcracks is affected by all these four factors. However, only the mineral composition has a significant influence on the proportion of transgranular cracks to intergranular cracks. In addition, compared with the grain size distribution and mineral composition, the average grain size and contact tensile strength have a more significant influence on fracture patterns. Article Highlights: A hybrid LS-DYNA and UDEC grain-based discrete element method (UDEC-GBM) was developed to evaluate blast-induced rock fractures.The influence of microstructures (e.g., average grain size, grain size distribution and mineral composition) and micro-mechanical properties on rock fracturing under blast loadings were investigated.The micro mechanism of granite fracturing under blast loadings was revealed.