STRESS EVOLUTION AND INDUCED ACCIDENTS MECHANISM IN SHALLOW COAL SEAM IN PROXIMITY UNDERLYING THE ROOM MINING RESIDUAL PILLARS
BAI Qingsheng1，2，TU Shihao1，2，WANG Fangtian1，2，YUAN Yong1，2
(1. School of Mines，China University of Mining and Technology，Xuzhou，Jiangsu 221116，China；2. State Key Laboratory of Coal Resources and Mine Safety，China University of Mining and Technology，Xuzhou，Jiangsu 221116，China)
Abstract：Mining in shallow coal seam，which in proximity underlying the room mining residual pillars，is mainly affected by the upper residual pillars and the active mining induced stress. According to the problems of huge ground pressure and support yield accidents during mining in the No. 3–1–2 seam in the Shigetai Coal Mine，integrated research methods of theoretical analysis，numerical simulation and field testing were undertaken for the mechanism of mining induced stress evolution and support accidents. The result shows that，in contrast with Mohr-Coulomb criteria，the strain-softening criteria is accurate to capture the mechanism of deformation and destruction of the residual pillars in the room mining goaf，under the condition of the lower longwall mining induced stress. In the conditions that the residual pillars were stable in the room mining goaf，and the mining face was underlying these stable pillars，as a result of the residual pillars concentrated stress and the mining induced stress，the roof of the underlying seam slicing and falling nearby the edge of the residual pillar，and this big loading results in support yield. Blasting the upper pillars was carried out before and during excavated the No. 3–1–2 seam，the roof pressure transfers into the distant rock(coal) in the front of the working face. This measure effectively reduces the concentrated surrounding rock stress in the lower longwall face，and enables mining safely in the shallow seam in proximity underlying the room mining residual pillars.
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2012, Vol. 31 
