Numerical simulation study of the support system by gob-side entry retaining by roof cutting

Abstract

Gob-side entry retaining by roof cutting (GERRC) is an innovative, long-wall mining method that has been widely used in China as a new mining revolution. However, current research on the influence of this technology on the support system remains limited. To understand the response of each supporting structure after cutting the roof, this study uses the cable element and beam element built in the finite difference software FLAC3D to simulate the bolt, anchor cable, steel beam, and single hydraulic props based on the engineering geological conditions of the Lvtang Coal Mine in Guizhou Province, China. Then, the force and displacement changes of each supporting structure between the GERRC and traditional coal pillar mining are compared and analyzed. Simulation results reveal that during the process of conventional mining, the force and deformation of anchor cable behind the working face is relatively large; furthermore, even yield and breaking of the cable occurs. Meanwhile, the serious deformation of a single hydraulic prop occurs, which affects the normal use of the roadway. When the GERRC is adopted, the force of each supporting structure is reduced by 17.6% on average and the deformation is not obvious. Moreover, using the GERRC decreases the stress of the supporting and reduces the displacement of solid coal in the roadway by 33.3%. Finally, the concentration degree of stress becomes lower, and the environment of retaining roadway is more optimized.