Mechanism and prevention of rock burst in coal seam roadway group considering time⁃varying characteristics

In view of the frequent occurrence of rock bursts in coal seam roadway groups at normal use，based on the time⁃varying characteristics， the mechanism of rock bursts in coal seam roadway groups is revealed by using the methods of field detection，mechanical analysis and numerical simulation，and a new prevention method is put forward. The results show that the structural area of central roadway，fault，fold and buried depth provide a high⁃stress basic environment. The superposition effect of the time⁃varying characteristics of the surrounding rock of the road⁃ way group with a long service cycle promotes the high concentration of the static load of the coal pillar between the roadway. The roof fracture with the increase of the suspended area in the roadway produces the dynamic load， which disturbs the static load of the coal pillar and induces the initiation of rock burst. The fundamental reason for the high concentration of static load of coal pillar between central roadways is the long beam cantilever and subsid⁃ ence of overlying thick hard roof slab，which intensifies with time until the fracture produces the dynamic load inducing impact. It is proposed that the prevention and control of this kind of rock burst should be aimed at the thick hard roof on the coal seam，which is artificially cracked to make its long beam become a short beam，so that it no longer has the cantilever function，and the overlying load changes from hard transmission to soft transmission. The deep hole fracturing test of the target rock stratum is carried out with a kilometer drill，which achieves the purpose of reduc⁃ ing the load of roadway surrounding rock and preventing rock burst.