Study of stability of surrounding rock and characteristic of overburden strata movement with longwall roadway backfill coal mining

In China’s western ecological fragile coal mining area,the traditional coal mining technology causes many environmental problems with low coal recovery. To solve the problems and to improve coal recovery,the longwall road- way backfill coal mining method was proposed as a solution. Through the systematic analysis of the roadway layout and backfill mining technology,the difficulties and key points in the technology were shown. Based on the strata movement characteristics in the roadway backfill coal mining,the mechanical model of coal mining in stope was established. Then,the equation of roof deflection curve with corresponding mechanical analysis and the calculation formulas of coal pillar were calculated. And an assessment on the instability conditions of the coal pillars were also provided combining the ultimate strength theory. Combined with one engineering case of roadway backfill mining in Shaanxi Changxing Coal Mine,with the test results of backfill material mechanical properties,the mining plan of roadway backfill coal mining was optimally designed. At the same time,the 3DEC numerical simulation software was used to study and analyse the overlying strata movement of the water-resisting layer in Yan’ an Formation interlayer fissure confined water and the Quaternary loose pore phreatic water. Field application results show that this technology can effectively control the stability of surrounding rock and the overlying strata movement of water-resisting layer,improve the recovery rate of coal resources and provide a reference for the coordinated development of the western mining area resources and envi- ronmental protection.