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Research on key parameters of gob-side entry retaining formed by roof cutting of working face under goaf in close distance coal seams

Shen Fuxin, Song Yanqi, Zhao Wenhao, Ma Hongfa, Zheng Junjie, Shao Zhixin

Mining Science

2022

Vol. 29

38-39

In order to solve the application problem of gob-side entry retaining formed by roof cutting (GERRC) technology of working face under goaf in close-distance coal seams, the 9101 working face and its return air roadway of Xiashanmao Coal Mine were taken as engineering background. The key parameters of GERRC were studied by means of theoretical analysis, numerical simulation and field test. The results show that: The roof cutting height (RCH) should be not less than the height of stope caving, meanwhile, when the rock strata collapsed, broke and expanded within RCH, it should meet the support effect on basic roof. And the RCH should be less than the distance between coal seams. The roof cutting angle (RCA) should meet the mechanical conditions of rock mass failure along the structural plane, and it should meet the geometric condi-tion of not squeezing the roadway roof during the rotation and subsidence of the stope basic roof. When the RCH was 7.5m, the RCA was 15 degrees and the blasting charge structure was 4+3+3+2, the stress distribution and roof subsidence were most optimal. Three rows of constant resistance with large deformation (CRLD) anchor cables were used to strengthen roadway roof. The unit support, hydraulic prop and π-shaped beam were carried out as temporary support in roadway. The surrounding rock of roadway tended to be stable when lagged behind 100m, and the effect of GERRC was good after the temporary support measures were withdrawn.