Influence of gas pressure on abutment stress and prevention of gas-rockburst composite disaster

Abstract

With the increase in the depth and intensity of coal mining, some coal mines encounter the dual disaster threat of gas outburst and rockburst, and the composite gas-rockburst disaster has become a scientific and engineering problem that deserves more attention, and the distribution of abutment stress is of great significance for revealing the mechanism of composite dynamic disasters. This paper focuses on the influence of gas pressure on the abutment stress, establishes a theoretical model of a circular roadway and obtains the influence of gas pressure changes on the tangential stress and the radius of the plastic zone. The influence characteristic of gas pressure on the front abutment of a longwall working face is simulated based on the typical engineering geological conditions of an outburst-rockburst mine. The results show that as the gas pressure decreases, the tangential stress around the roadway increases, and the radius of the plastic zone decreases, meaning that the peak tangential stress is closer to the roadway. The peak abutment stress is negatively correlated with the gas pressure, while the distance of the peak from working face is opposite, both showing a quadratic relationship. On-site monitoring shows that as gas extraction proceeds, the frequency of mining-induced tremors increases significantly. When there is a sharp upward trend of the mining-induced tremors along with the continuous decrease of gas pressure, the risk of rockburst is high. A gas-rockburst coordination prevention and control technology system is established in Haishiwan Coal Mine based on the relationship of gas pressure changes and rockburst danger. During the gas control process, the gas pressure-microseismicity frequency is used to predict the rockburst risk and optimize the starting position and strength of destress engineering to achieve collaborative prevention and control of outburst-rockburst.

Keywords

• gas-bearing coal seam
• abutment stress
• gas pressure
• composite dynamic disaster
• rockburst