Law of overburden movement in coal seam group mining and the determination of 'three zones' height

In order to study the law of overburden movement and the distribution range of “three zones” under the condition of coal seam group mining, based on the general situation of 42106 working face of Shendong Buertai Coal Mine, the physical experiment method of similar model is used to simulate the overburden movement characteristics of 2-2 coal and 4-2 coal successively, and the characteristics of overburden caving, stress change and strata subsidence are compared and analyzed respectively. The results show that after the mining of the upper coal seam face, the failure degree of the overlying rock is low as a whole, and the stress peak value mainly exists in the leading influence area of the working face, block hinge and so on. After the lower coal mining, the fracture zone communicates with the upper coal goaf, resulting in that the fracture zone of the goaf of the composite coal seam is much larger than that of the upper coal seam, the stress is larger than that of the upper coal seam as a whole, and the roof subsidence increases significantly. The overburden has gone through three stages of separation and separation increasing, and finally closed. The “three zones” height of 42106 working face is determined by the data measurement of observation points, and the borehole monitoring is carried out in the field to verify the rationality of similar physical simulation results.