Experiment on Longwall Mining with Coal Rejects Backfill in Thick Seam with Shallow Depth Under Buildings

According to the high thickness and shallow depth features of the seam in Dongping Mine of Yangquan under the buildings, based on the fully mechaniz ed longwall mining coal technology with rejects backill, the technical access of the longwall mining with coal rejects backfill and the interval slice seam was provided to liberate the seam under the surface buildings.Based on the analysis on the subsidence control mechanism of the longwall mining with coal rejects backill, the equivale nt mining height conception was applied to design the slice mining thicknesses individually as 3.1 m and 3.0 m in the experiment region. The surface subsidence predicti on was conducted to the mining alternatives.The results showed that after the first slice mined, the surface ground displacement and deformation value would be within the preset prevention standard.After the stabilization of the first slice mining, a simple repair and reinforcement were made to the buildings on the surface ground.Then the second slice seam could be mined and the surface displacement and deformation could be still within the preset prevent standard.Thus a safety and economic ratio nal mining method could be provided to minimum solve the problems of the coal seam under the buildings.