Mechanism and application of a new method for roof cutting and pressure relief with dense drilling
Authors: FU Qiang, YANG Jun, GAO Yu-bing, LI Chang-jiang, LIU Yu-xuan, JIANG Han-ze, ZHOU Jian-lin, WU Xing
With the continual deterioration of mining conditions, the deformation and failure of surrounding rock in roadways with weak roofs under intense mine pressure during close-distance coal seam extraction has become a critical issue restricting the safe and efficient mining of coal. To address the issue of increased surrounding rock damage caused by blasting pressure relief in such roadways, this study proposes an innovative non-explosive method for roof cutting and pressure relief with dense drilling (RCPRDD) to protect the roadway. A combined approach of laboratory experiments, theoretical analysis, numerical simulation, and field testing was employed to clarify the rock weakening effects and mechanisms induced by dense drilling. An optimal design method for drilling diameter and spacing was established, and the effectiveness of this method was validated. The research results indicate that the degree of rock weakening induced by dense drilling is primarily related to the drilling density coefficient. As the drilling density coefficient increases, the rock weakening effect becomes more pronounced. At the same time, dense drilling exerts a significant amplifying effect on the tensile stress experienced by the side roof of the roadway goaf. A functional relationship between the dense drilling weakening coefficient and the drilling density coefficient was established, providing a theoretical basis for the selection of key parameters for dense drilling. The method was ultimately implemented in a field engineering test, effectively reducing the stress in the coal body of the advanced roadway, controlling the deformation and failure of the surrounding rock, and achieving the goal of protecting the roadway. This demonstrated the feasibility and effectiveness of the RCPRDD. The research findings provide a scientific basis for controlling roadway deformation under similar conditions.
