| Gob-side entry retaining is of great significance to improve coal recovery ratio, reduce roadway tunnelling, gas disaster prevention. Because of high stress concentration and strong dynamic pressure, the roadway deformation is severe and difficult to maintain when gob-side entry retaining is launched in thick coal seam top-coal caving mining face. The key to gob-side entry retaining in top-coal caving mining face (GERTCF) is the stability of surrounding rock control. It is of important theoretical value and practical significance for carrying out surrounding rock control technology in GERTCF.Through theory analysis, similar material simulation, numerical simulation and field test, this dissertation study the strata structure damage characteristics, roadway-side supporting resistance, deformation law of surrounding rock about GERTCF. The feasibility analysis method of GERTCF is proposed. The main research achievements are as follows:Breakage forms and key block parameters of lateral roof in gob-side entry retaining are analyed. The influence factors of surrounding rock stability are analyzed, and the surrounding rock deformation characteristics of gob-side entry retaining is revealed. On the basis of the key strata theory, surrounding rock structure mechanical model of GERTCF is established and the theoretical formula of supporting resistance is confirmed. According to energy conservation and damage mechanics theory, roof subsidence damage mechanics model of the gob side entry retaining in fully mechanized caving face is built and roof subsidence analytic solution is carried out. Influence factors of roof subsidence are analyzed. On the basis of plate-shell theory and minimum potential energy principle, immediate floor and basic floor mechanical model in gob side entry retaining in fully mechanized caving face is established. Floor heave calculation method is put out and influence factors of floor heave are analyzed. The feasibility analysis index of GERTCF is proposed, and GERTCF feasibility analysis method is established by using fuzzy theory and AHP. By using the similar material simulation experiment and digital speckle, rock displacement features of GERTCF are analyzed, and relationship between lateral roof caving and stress distribution of roadside support body is studied. By using three-dimensional numerical simulation, the roof stress evolution rule and rule of roof convergence of GERTCF are studied, and influence on the stress field and roof subsidence caused by gob-side entry retaining width, the roadside support body strength and width is analyzed. This dissertation puts forward the control countermeasures of surrounding rock deformation in Wuyang coal mine, which is "bolt-mesh-anchor + high strength pier + timber crib + basic bottom grouting". Entry-in support design and roadside support parameters are determined, and the support design reliability is also analyzed.The research results are applied successfully in 7602 fully mechanized mining face of Wuyang coal mine. Results show that selected support scheme can fairly well solve the surrounding rock deformation, which provides a successful GERTCF case for similar condition coal mine. |
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