Study on mechanism of rock burst and early warning of typical steeply inclined coal seams

Due to the special coal and rock occurrence and mining method,the breaking motion of overburden rock and the resulting surrounding rock static stress distribution and dynamic disturbance characteristics are quite different from those of gently inclined coal seams. The rock burst disaster has occurred in steeply inclined coal seams(SICS). To guide the prevention and control of rock burst in similar existing mines,taking the typical SICS in the south mining area of Wudong Mine as the engineering background,a systematic study has been carried out from the mechanism,early warning and prevention technology of rock burst. The coupled mechanism of compression and prying-induced rock burst in SICS is revealed. The early warning index system suitable for SICS is established,and the prevention and control technology of rock burst in SICS is put forward. The results show that the damage of rock burst under fully-mechanized top-coal caving mining of SICS has the characteristics of asymmetry on both sides of the roof and floor roadway,and compression and prying damage characteristics. The compressive and pried stress acted on the coal body is the basic static load that induces the rock burst. The rupture of the suspended roof and rock pillar have important inducing effects on the rock burst. The rock burst in SICS under fully-mechanized top-coal caving and filling mining is induced by coupling of compressive and prying action. Each index has obvious response characteristics to rock burst risk and high energy tremor. The comprehensive early warning of each dimension and each system early warning index can integrate their respective advantages to achieve complementarity and improve the accuracy of early warning. The alternate deep and shallow hole blasting can weaken the pressure load and the prying effect on the coal body,the daily total energy and event count of microseism are obviously reduced after on-site implementation. The average number of microseismic events occurred on roof and rock pillar above 104 J per meter is reduced by 96% compared with that before implementation,the pressure relief effect is obvious,and the rock burst risk is reduced.