| To solve the difficult technical problems of intensive strata behaviors and bad stability of rib spalling in working faces with great mining height, taking the working face with mining height of 6.0m in Sihe Coal Mine, Jincheng Mining Grop as an engineering background, the strata behaviors, the structure of upper strata and the mechanism of rib spalling are studied with methods of measuring in-situ, mechanical theroetic analysis and numeric simulation.(1)The theory of key strata is used to research the structure of the overlying strata. There are two key stratas in the overlying strata of 2307 coal face in sihe coal mine.The instable type of key strata is analyzed by the theory of"S-R".(2)The preliminary law of strata behaviors of fully mechanized mining coal face with great mining heitht is got with methods of measuring in-situ.(3)The motion law of the overlying strata is researched by the 3DEC numerical simulation software. The increase of bulking factor and bed separation and the advance of fracture line of the roof are the main fature of fully mechanized mining with great mining heitht.(4)The law of the stress distribulation and the featrue of the wall depredation are researched by FLAC3D software. There are three districts in front of the wall: tension-plastic district, shear-plastic district, elastic district. The peak position of abutment pressure is the critical point of the shear-plastic district and elastic district.There is critical mining height of easily wall depredation in fully mechanized mining coal face with great mining heitht.(5)The mechanism of the rib spalling is preliminarily studied by the suppressed shaft and the results are tested and verified by the measuring in-situ results. There are two type of wall depredation: half of wall depredation and whole wall depredation. The 0.65 times of the wall is the easiest unstable position. Finaly, we get that the distinct coal strength has different depredation type.All of the results are the basis of strata control.
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