Numerical analysis of deep hole multi-stage cut blasting of vertical shaft using a continuum-based discrete element method

Abstract

Due to the high in situ stress of the deep rock mass and the restraining effect of the surrounding rock, the deep hole blasting of vertical shaft faces the problems of low borehole utilization rate and poor blasting effect. In this regard, this paper proposes a deep hole multi-stage cut blasting technology of vertical shaft. Preliminary engineering practice shows that such cut blasting technology can make better use of explosive energy, reduce the restraining effect of surrounding rock, and increase the borehole utilization rate. Furthermore, based on the continuum-based discrete element method (CDEM), the fractal damage, fragmentation, and blasting cavity characteristics of deep hole multi-stage cut blasting of vertical shaft are studied and analyzed. The results show that in the multi-stage cut blasting of vertical shaft, if the length proportion of the first stage is too small or too large, it will lead to poor cavity formation along the cut direction. Characteristic parameters such as fractal damage of blasting cavity, fracture degree of element, and fracture degree of interface show a trend of first increasing and then decreasing as the length proportion of the first stage increases, and the length proportion of the first stage has an optimal value. Under the conditions of rock parameters, explosive performance and linear charge density set by the numerical simulation in this paper, when the length proportion of the first stage accounts for 0.42, the multi-stage cut blasting of vertical shaft can make better use of explosive energy and achieve the best blasting effect.