Study on Activation Laws of Overlying Strata During Strip Coal Pillar Recovery by Paste Backfill

To study the activation laws of overlying strata during strip coal pillar recovery by paste backfill, three models of strip mining, residual coal pillar recovery and separate filling mining were established. Based on the numerical simulation and the actual measurement of surface subsidence of coal pillar in the belt of paste filling recovery in Daizhuang Coal Mine, the mechanism of overburden activation caused by filling and mining of isolated island coal pillar and the influence of overburden activation on surface subsidence are studied. The results show that the activation degree of overburden in filling mining tends to increase first and then decrease with the increase of the distance from the coal seam, and the maximum activation occurs within 100 m from the coal seam; the ratio of activation of overlying strata during strip coal pillar recovery by paste backfill is 15% to 30%, the surface is about 15%.