Research on Key Parameters of Cutting and Retaining Roadway of Thick Coal Seam in Fully Mechanized Caving and Its Engineering Application

[Purposes] This article aims to solve the stability problem of the roadway after using concrete flexible mold filling technology to leave the roadway along the goaf in the working face. To solve the problem of roadway stability after retaining the roadway along the goaf, “ flexible mold filling + shaped charge blasting pre cracking technology” is adopted. [Methods] On the basis of the characteristics of the roof overlying rock of the working face, the method of theoretical analysis and numerical simulation, combined with the site construction conditions, is used to determine the deep hole precracking blasting scheme with the cutting height of 20.5 m and the cutting angle of 5°. [Findings] The results show that the elastic-plastic boundary in the coal wall moves in, the range of the internal stress field increases, and the effect of the high masonry beam structure is obvious. With the increase of the cutting height, the support resistance of the filling body and the deformation of the surrounding rock decrease first and then stabilize. With the increase of cutting angle, the support resistance of backfill and the deformation of surrounding rock increase continuously. The deformation of the surrounding rock is reduced by 56% and the displacement of the roof and floor is reduced by 72%, which reduces the maintenance cost in the later period and provides an empirical reference for the mining roof cutting and roadway retention under similar conditions.