Similar Simulation of Mining Cracking Evolution Law for Overburden Strata Above Coal Mining Face

In order to obtain a development height and evolution features of cracking zone above mining face in mine under thick aeolian sand area of thin bedrock,base on the three zones of the overburden strata divided above the coal mining face,the similar material simulation experiment was applied to study the cracking development features in the seam mining process under thick aeolian sand area of the thin bedrock area.During the mining process,the falling failure features and movement law of the top overburden strata as well as the internal pressure distribution law of the strata were obtained.A relationship between the development height and existed shape of the mining cracking zone and the pushing forward speed of the coal mining face was analyzed.The results showed that the periodical roof weighting step of No.12406 coal mining face in Bulianta Mine was 22.5 ~ 30.0 m.A broken angle of the top overburden strata at the goaf side was64° and the broken angle at the coal wall side was 61°.The height of the cracking zone was 157.1 m and was 26.18 times of the coal mining height of the coal mining face.A subsidence tendency of the overburden strata above the coal mining face was in nonlinear curve and the moving shape was in asymmetry.