Application Research on Gob-Side Entry Retaining Methods in No. 1200 Working Face in Zhongxing Mine

Aiming at the serious deformation problem of the roadway supported along gob-side by stowing with high-water-content packing on the engineering background of No. 1200 working face, the technologies of supporting beside the roadway by stowing with high-water-content packing and relieving pressure by roof-cutting along gob-side entry are applied in different sections respectively. Based on the engineering geological conditions of the working face, the roof-cutting parameter is calculated and some technologies have been put into use in the project: high constant resistance and large deformation (CRLD) cable supporting technology; bilateral cumulative tensile explosion technology; gangue blocking supporting technology. Arm-shortening beam resulting from roof-cutting cuts down the cantilever beam length of roadway roof. CRLD cable supporting can effectively improve the mechanical properties of roof strata. The roof collapses smoothly within the height of cutting seam along the gob-side entry, filling the gob with gangue quickly. The point where the gob roof touches the collapsed gangue moves toward the remained roadway side and the subsiding and rotary deformation problem of gangue-formed wall gets under control and the subsiding level is reduced. Compared with the original backfilling body, the collapsed gangue weakens the level of stress concentration. Meanwhile, the subsiding of minor roofs and the roof strengthening can dramatically reduce the bottom heave. Engineering practice has proved that in such mining geological conditions, the method of releasing pressure by roof-cutting along gob-side entry can effectively decrease the deformation of the retained roadways, greatly reduce the workload, enhance productivity and guarantee the remarkable benefit of retaining roadway economy.