Study on the development characteristics and height of "three zones" of the working face covered with thick alluvium and weak overburden

In order to study the migration law of subsidence overburden strata under the geological condition of thick alluvium and weak overburden, based on the mining geological conditions of 11915 working face in Gequan Coal Mine, this paper analyzed the dynamic process of the first caving of the immediate roof and the failure of high overburden when the working face was advancing through the indoor similar simulation method. The height range of overburden caving zone, fractured zone and bending subsidence zone (referred to as "three zones") was obtained; the displacement characteristics of strata in the "three zones" of subsidence overburden were analyzed, it reflected that the strata displacement curves in caving zone, fractured zone and bending subsidence zone show decreasing fluctuation trend. The results show that the caving zone of 11915 working face ranges from 10 m to 25 m, the height of the fractured zone ranges from 43 m to 48 m, and rock strata above 48 m belongs to the bending subsidence zone. The similarity simulation results are close to the field measurement results, which verifies the rationality of the similarity simulation experiment.