Theoretical analysis model and optimization scheme of shape-effect damage in cut blasting

Abstract

Abstract To explore the rock-breaking mechanism of cut blasting under the influence of empty holes, based on the principles of the empty hole effect, stress concentration effect and expansion space theory, the stress distributions of empty hole walls are calculated, and a two-dimensional damage analysis model of shape-effect segmented blasting is established. On this basis, the theoretical analysis model of square hole cutting is given as an optimization scheme, and the model is demonstrated by numerical simulation. The results show that the optimized load function γq2sinθ with time is consistent with the actual stress of the hole wall, and the change trend of the theoretical calculation is consistent with the simulation results. The change in the shape of empty holes in a rock mass will affect the stress distribution of the surrounding rock mass. The stress waves with square holes cause tensile–shear failure in a wide range of rock around the hole wall, while the rock near the circular hole wall produces ring-shaped failure. The reflected tensile stress waves are influenced by the impedance of the circular hole. In the optimized scheme, the cracks around the holes are uniformly connected, the rock mass collapses inward under the influence of the holes and the two-stage stress waves, and the utilization rate of the hole space reaches 56.091%.