Improved comprehensive index evaluation method and its application on rockburst hazard of gas coal seam

In order to study the influence of gas on the rockburst hazard of coal seam,a gas inflating system for testing coal samples was developed,and a method of impact tendency testing for gas-containing coal was developed.Four impact tendency indexes of coal,which including the uniaxial compressive strength,dynamic failure time,impact energy index and elastic energy index,were measured under the gas pressure of 0,0.5,1.0,1.5，2.0 MPa.The test results show that the impact tendency of coal decreases as its internal gas pressure increases.Based on the comprehensive index evaluation method,considering the influence of gas on the rockburst hazard of coal seam,an improved comprehensive index evaluation method of rock hazard was proposed.In this method,the coal seam gas property was regarded as a kind of geological factor,and the gas drainage effect was regarded as a kind of mining technical condition.The improved comprehensive index evaluation method was used to evaluate the rockburst hazard of high gas coal seam in the second panel of a coal mine.It is found that the evaluation result of both geological conditions and mining technical conditions have a good consistency.