Damage mechanism and fracture evolution of rock containing defects with LCEM-GFEM method under explosive load

Abstract

Defects in rock masses have significant influence on the fracture propagation during blasting. In this study, a numerical model is developed using the local cohesive element based on the global finite element method (LCEM-GFEM) to simulate the damage evolution and fracturing pattern of rock mass with defects under blasting load. The influence of defect morphology on the stress wave transmission and attenuation is quantified by introducing the energy transfer coefficient. The numerical results show that the defect morphology has prominent influence on the damage characteristics and fracture propagation of rock masses. The merging path of the blast-induced fracture and the derivative fracture shifts from the end to the middle of the defect as the angle of parallel defects increases. The energy transfer coefficient increases with the angle of parallel defects, while the fractal dimension decreases in this case. The number of fractures between the parallel defects and the energy transfer coefficient reduces significantly with the horizontal distance between parallel defects. With the increase of perpendicular distance between the vertical defects, the length of the main horizontal fracture passing through the defect C increases, as well as the energy transfer coefficient and fractal dimension. The numerical results would be beneficial to the understanding of the damage characteristics of defective rock masses under blasting load.

Keywords

defective rock mass / LCEM-GFEM / crack propagation / cohesive element / fractal theory

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