Theoretical analysis and experimental investigation on failure characteristics #br#
and stability of stope floors
SONG Wencheng1，2，LIANG Zhengzhao1，2，LIU Weitao3，ZHAO Chunbo3
(1. State Key Laboratory of Coastal and Offshore Engineering，Dalian University of Technology，Dalian，Liaoning 116024，China；
2. Center of Rock Instability and Seismicity Research，Dalian University of Technology，Dalian，Liaoning 116024，China；
3. College of Mining and Safety Engineering，Shandong University of Science and Technology，Qingdao，Shandong 266590，China)
Abstract：In order to investigate the fracture characteristics and water outburst risk of mining floors above confined aquifer，mechanical models of both stope floors and water-resisting key strata were constructed to theoretically calculate the longitudinal failure range and transverse water-inrush zone of the floor under periodic weighting，and the fracture characteristics and seepage trend of the mining floor above confined aquifer were revealed using finite difference hydro-mechanical coupling modeling method and similar simulation test. The theoretical calculation shows that after coal seam excavation，the failures of the floor along the strike and inclination of the working face present“spoon-shaped”and“inverted saddle-shaped”respectively，and that the maximum failure depth of the floor is located near the boundary between the mined-out area and the coal body，which is roughly similar to the simulating result. The water gushing positions of water-resisting key strata are theoretically located in the areas including the side of the working face，50 m behind the coal wall and both sides of the goaf. However，the risk of water inrush in the central part of the side area of the working face is the highest，which coincides with the experimental observations and the numerical phenomena. It is observed that the shear and vertical cracks well develop in the shallow floor near the mining face and starting cut while that the layered cracks appear in the rock mass below the goaf. The maximum damage depth obtained by the test is 12.8 m，slightly less than the theoretical calculation and numerical simulation results of 13 and 15.875 m. The research results of this paper reveal the water inrush location and risk of mining floor，which can provide a theoretical basis for mine water treatment.
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2019, Vol. 38 
