Study on key parameters of bidirectional shaped charge blasting for gob side entry retaining with roof cutting and pressure relief

Abstract

Through the combination of theoretical analysis and numerical simulation, the directional fracture law of rock under the action of bidirectional shaped charge blasting and the crack propagation law of rock under different spacing of double hole shaped charge blasting are analyzed. The results show that the two-way shaped charge blasting can effectively fracture the roof directionally; when the distance between blastholes is 500 mm, a good through-crack can be formed between the two blastholes. Based on the numerical simulation results, previous research results and the engineering geological conditions of the working face, the blasting test scheme is formulated. The test results show that the single hole charge structure of 4+4+3+3+2 can effectively pre-crack the roof; when the distance between boreholes is 500 mm, the effect of roof fracture is the best; the results show that the closer the support is to the cutting line, the smaller the maximum working resistance is, which verifies the feasibility of blasting parameters.

Keywords

• cutting top pressure relief
• energy gathering blasting
• damage of blasting rock
• numerical analysis
• blasting parameters