Study On Mechanism And Control Technique Of Roof Fall And Support Collapse Large Slope Fully Mechanised Caving Face Under Complex Conditions

Based on the geological and production conditions of 2313 large slope fully mechanized caving face in Geting coal mine, using application of field survey, numerical simulation, mechanics analysis, field test and the other methods, this paper deeply studied the mechanism of head face top-coal caving, stability of hydraulic supports and their control technique. The research achievements are of great significance to promote safety and high efficient coal mining of large slope fully mechanized caving face.Due to the complex conditions such as numerous faults, vary collapse columns, low strength coal mass, numerous joints and cracks in large slope fully mechanized caving face, and because of top coal above hydraulic support having a larger component force sliding downward along the working face tendency and disturbance of advancing supports and coal caving, support-surrounding rock system is inclined to occur roof fall and support collapse accidents.UDEC numerical simulation was applied to analyze the influencing factor of coal and rock mass, control effect of the large slope head face, and characteristic of top coal caving. The result shows that head face distance of supports should be less than 0.75m, the critical value of support working resistance and horizontal working resistance should be 3600kN and 160kN respectively, and their direction should be directing to the coal wall. Through mechanical analysis on support stability, this paper obtained coal seam critical inclination value for supports nonoccurrencing collapsing and gliding while roof caving was empty and minimum bearing power of support and column without dumping and sliding down while advancing supports. According to mechanics model analysis on support horizontal structure stability, this paper determined calculation formula of minimum support force for support moving under press and maintaining stability.Strata control observation, statistic analysis, and the measures for control roof fall and support collapse were carried out in 2313 large slope fully mechanized caving face of Geting coal mine, and we have achieved fully mechanized top-coal caving face mining safety and efficiency under the complex conditions that the average inclination is 36°and the maximum angle is 51°.