The damage process of fractured rock mass showed that the fracture in rocks induced roof collapse in Yangchangwan Coal Mine,China. The rock mass was particularly weak and fractured. There occurred 6 large-scale dynamical roof falls in the excavation disturbed zone(EDZ) with the collapsing volume of 216 m3. First,the field detailed geological environment,regional seismic dynamics,and dynamic instability of roadways were generally investigated. Second,the field multiple-index monitoring measurements for detecting the deep delamination of the roof,convergence deformation,bolt-cable load,acoustic emission(AE) characteristic parameters,total AE events,AE energy-releasing rate,rock mass fracture,and damage were arranged. Finally,according to the time-space-strength relations,a quantitative assessment of the influence of rock-mass damage on the dynamic roof instability was accomplished.
In virtue of effect of N-S intensive ground stress and mining disturbance to +579E2EB_(1+2) mining site at Weihuliang Mine,the dip angle and section height is 65° and 52 m,respectively,the collapses happed frequently during mining.Firstly,mining condi- tions,spatial structure and parameters were investigated.Then physical simulation and dynamic numerical tracing and elaborate simulation relating roof and top-coal were ap- plied based on 2D-Block Program and quantitative regularity of stress at variable depths had been estimated.Furthermore,it was manifested that effective measures,i.e.,fast mining,control symmetrical top-coal-caving at dip and strike directions,optimizing ventila- tion system,active-stereo preventing gas were performed successfully in mining practice. Ultimately,the derived dynamic hazard were prevented so as to safety mining.
