Study On Reasons Of Rock Burst In Roadway And Prevention Technology Of Steeply-inclined And Extremely Thick Coal Seam With Horizontally Slicing Way

To mine the extremely thick and steep-inclined coal seam, a multiple-level sub-level caving method has been utilized in Huating mine of Gansu Province. Frequent rock-burst occurred in recent years have incurred serious casualties and economic loss. The rock-burst is a new project for Huating mine stemming from the specific coal seam sentimental condition and mining method.Based on the rock busting conditions of Huating mine, the overburden's movement and rock pressure behavior characteristics have been deeply studied by comprehensively utilizing theoretical analysis, laboratory and site testing, similitude material simulation, and numerical modeling while accomplishing the testing of the rock-burst proneness of the coal seam and site-situ stress.The main achievements obtained in the dissertation are:(1) It was studied and verified that, under Huating mine geological conditions, the multiple-level sub-level caving method can typically cause large overburden displacement, rock proneness, high level of stress concentration, and high energy accumulation. It was also found that the development of the gob in the steep-inclined coal seam is a progressively dynamic and subsidiary funnel; a cantilever structural model was advanced and established according to the steep-inclined seam in Huating mine and mining method; a dual feature of the periodic pressure occurring in both longitude and dip was analyzed and demonstrated; high stress concentration and energy accumulation around the longwall panel causing rock burst proneness.(2) The rock burst results from multiple factors: roof and coal seam with burst proneness; high field stress level caused by deep mining and a syncline; additional mining stress around the panel caused by the high coal production and large overburden displacement; dynamic stress concentration caused by the superposition from multiple workings; the dynamic load yielded from the cantilever failure inducing and strengthening the rock burst..(3) An effective way has been established in preventing and reducing the rock burst for Huating mine. Accordingly, a comprehensive method, including mining intensity reduction, deep hole roof exploration, and entry support reinforcement, has been formulated as well.(4) Based on the model of the cantilever beam established for the steep-inclined thick coal seam, the stress-relieve method via deep hole exploration has been implementing underground.(5) It was found that rock bolting is the optimal way in preventing and reducing the rock burst. A rock-burst resistance rock bolting system been put forward while analyzing the rock bolting principle in rock burst entry. Meanwhile, a theory of rock bolting system specifically in resisting the rock burst, high bolt strength, pressure relieve at a high stress level, and integrity, has been developed.(6) The methodology, energy calibration, of rock bolting design for resisting rock burst has been developed: First of all, proneness prediction of the entry; Secondly, parameter optimization via numerical modeling; Finally, parameter calibration based on the rock burst theory.