Study on the effect of empty hole diameter on cut blasting under biaxial confining pressure in deep rock roadway

Abstract

In order to study the effect rules of empty hole diameter on cut blasting effect in deep rock roadway, this study uses ANSYS/LS-DYNA software to simulate and analyze the cut blasting model with different empty hole diameters under biaxial confining pressure based on the experimental parameters. The self-designed large-scale combined loading steel frame and electro-hydraulic servo loading system were used in the experiments on cubic cement mortar blocks with side length of 600mm and sand cement ratio of 2:1 to study the variation of crack propagation and cavity characteristics of rock mass under different empty hole diameters. The relationships between diameters of empty holes and cavity depth and volume are numerically fitted and analyzed. The results show that with the increase of the diameter of empty hole, the magnitude of strain around the blastholes increases, and stress concentration effect of the rock mass around the holes increases, the coupled stress waves formed by the superposition of initial stress field and explosion stress wave propagate earlier to the boundary of empty hole wall and reflects, and the reflective tensile damage zone of the rock mass near the empty hole increases. Under the condition of constant spacing between blastholes and empty holes, when the diameter of empty holes is between 20mm and 24mm, the effect of rock breaking and cavity forming by deep rock cut blasting have better effects.