On optimization of pressure-relief parameters of water jet slots in deep rockburst coal seams

In order to determine the optimal parameters of pressure relief by high-pressure water jet slotting in deep rockburst coal seams, the principles of pressure relief and impact prevention are analyzed through numerical simulation and theoretical deduction. The theoretical model for parameter optimization for four factors, such as drilling spacing and slot radius, is established. Based on the principles of dynamic and static load superpositions, the mechanism of rockburst in the concentrated roadway in mining area No. 730 of a mine is studied, the theoretical parameter values of each influencing factor are obtained, and the similarities and differences of stress, plastic zone and impact risk index under different theoretical parameters are revealed. The results show that all the influencing factors have a great influence on the pressure-relief effects of high-pressure water jet slotting, and there is a significant interaction between the factors. The average vertical stress after pressure relief, elastic energy density, impact danger index and pressure relief cost are used as the effectiveness and economic indexes of pressure-relief parameters, and the advantages and disadvantages of the pressure-relief effects of different parameters are evaluated so as to obtain the optimal pressure-relief parameters of high-pressure water jet slotting under the physical and mechanical properties of the coal seam. After the application of the research results in the contact lane No. 3 of the mining area No. 730, the frequency, total energy and spatial concentration of microearthquakes in the site are greatly reduced, which provides technical support for the safe mining of the working face.