Research on the type and occurrence mechanism and prevention of coal pillar rockbursts

Coal pillar rockburst is a typical type of rockburst occurring in coal mining in China in recent years. How to summarize the engineering scale damage characteristics of coal pillar rockburst, reveal the mechanism of rockburst instability and formulate scientific and accurate anti-burst measures has become a difficult problem for coal mine science and technology personnel. The engineering characteristics and burst manifestation characteristics of three types of typical coal pillar burst accidents in China's coal mines are analyzed using field investigation, theoretical analysis and field monitoring, and the current coal pillar type burst in China is classified into three types: ground pressure superimposed type, cut creep type and overall destabilization type. The mechanical models of the occurrence mechanism of the three types of coal pillar burst are established respectively, the evaluation methods and prevention countermeasures of the three types of coal pillar burst hazards are proposed, and the occurrence mechanism of the three types of coal pillar burst is revealed. The mechanism of superimposed ground pressure type is that the superimposed stress applied to the coal pillar exceeds the critical value of the coal mass for burst instability, and the coal pillar is destabilized by minor or unconditional perturbation; the mechanism of overall instability burst is that the load borne by the coal body in the elastic bearing zone of the coal pillar exceeds its ultimate bearing capacity, and the coal body in the elastic bearing zone triggers the burst and causes the coal body in the shallow part of the coal pillar to fail extensively. The mechanism of cut creep rock burst is that the load transfers to the elastic bearing area due to the slow decrease of supporting capacity of coal pillar under long-term high stress, and when the load of the coal body in the elastic bearing area exceeds the critical value of burst, a large-scale coal body impact destabilization will occur. Due to the complex mining conditions in China, there are many hidden types of coal pillar bursts encountered during field production, therefore, in the prevention and control of bursts, it is necessary to strengthen the identification and prevention of these hidden coal pillar burst risks.