Research On Overlying Rock Movement And Fissure Evolution Law In Shallow-buried Coal Seam Working Face Under Peak-cluster Landform

The surface of shallow coal seam in Guizhou mining area is mostly peak cluster landform,which forms the characteristics of shallow coal seam mining under peak cluster landform.In the process of mining,the law of overburden fracture and fracture evolution is different from that in plain and gully mining area,which causes certain safety hazards to mine production and surrounding residents.In order to deeply understand the differences,this paper uses the research methods of theoretical calculation,similar simulation and numerical simulation to systematically study a process of overlying strata movement and fracture evolution caused by 11013 working face advancing through the mountain in Pusa coal mine,as well as the prediction of the height of water flowing fracture zone.Through the construction of elastic thin plate model,the basic roof breaking law and the height of water flowing fractured zone in the mining process of coal seam are analyzed theoretically.It is concluded that there are only caving zone and fractured zone in the overburden rock distribution in the mining process of working face,which is basically consistent with the definition of general shallow coal seam.The simulation models of working face in mining area were established by using the method of similarity simulation and numerical simulation,and the movement of overlying rock,fracture evolution and height of water flowing fracture zone in the process of mining were studied.It is concluded that the height of water flowing fracture zone and the basic breaking step are basically consistent with the theoretical calculation results,which achieves the effect of mutual verification.In the mining process of working face,the fracture development degree of overlying strata caused by the downhill section of the mountain is improved until it leads to the surface,which indicates that the fracture development of overlying strata is greatly affected by the surface under the peak cluster landform.In the experiment,the overall shape of fracture distribution is similar to trapezoidal shape.When the working face mining to the downhill stage,the basic roof cycle weighting step,stress peak and surface subsidence change show the particularity of peak cluster landform,and the surface subsidence curve is similar to teapot shape.The study reveals the evolution process of "incubation expansion closure" of overlying rock fractures in shallow coal seam mining with peak cluster landform.The research conclusion can provide a certain theoretical basis for coal mining under similar geological conditions.