Study on the Bending Effect and Rock Burst Mechanism of Middle Rock Pillars in Extremely Thick Subvertical Coal Seams

Rock bursts occur in nearly vertical coal seam mines at shallow to moderate burial depths, which endangers safe mining. To study the rock burst mechanisms of and extremely thick seams, characteristics were studied via on-site investigation, a field test situ stress was carried out. The mechanical behavior pillars middle B1+2 B3+6 seams analyzed using theoretical numerical simulation methods. results show that horizontal maximum principal orientation strike both 82°. bending occurred due unbalanced force, large amount energy accumulated within 50 m above mining level. bent toward goaf exerted reverse squeezing effect on below levels. In addition inclination compression roof, concentration zones formed seam, where elastic had coal-rock mass. Consequently, body level are an unstable state undue disturbance. theory calculation showed density mass reached or exceeded its critical value before occurred, prone under disturbances. microseismic high-energy events mainly concentrated around levels high-stress zones.