Cause Mechanism and Prevention and Control Countermeasures of Dynamic Disaster of Outburst Coal Seam under Thick Hard Igneous Rock

With water and gas outburst accident at 2# surface of Yangliu coal mine as a case, this paper studies the impact of magmatic intrusion on pore structure of coal, by combining theoretical analysis and numerical simulation, analyzes fracture evolution law of overlying strata of protective layer under thick hard igneous rock, and the cause for water and gas outburst accident at surface borehole. The analysis results show that, there are large quantities of pyrolysis pores in coal seam nearby igneous rock, which strengthens the adsorption ability of coal seam; the thick hard igneous rock has controlled whole movement of overlying strata. In sagging zone, there are areas where fractures and separation layers are unclosed for a long time, which provides enrichment area and migration pathways for gas and water; when igneous rock loses stability suddenly, it will release a lot of elastic strain energy instantaneously, which induces the occurrence of dynamic disaster. Based on the research results, the prevention and control countermeasures against composite dynamic disasters are put forward.