:Research On Strata Pressure Regularity Of Fully Mechanized Caving Face In Niangmute

The coal mining area of the first mining area of the Nemu coal mine belongs to the large dip coal seam and is not yet mined,and the permafrost is 20m-70m thick.The problem of the ground pressure in the mining face of the large dip seam in the permafrost layer is not yet studied.The particularity determines the particularity of the law of mine pressure.The effect of permafrost on the mine pressure law is mainly manifested in the fact that the breakage of the permafrost is facing the impact of the strata pressure,which poses a serious threat to the personal safety of the underground production personnel.Therefore,it is urgent to study the law of mine pressure in the first fully mechanized longwall top coal caving face.This paper mainly studies the relationship between the physical and mechanical properties of permafrost and the temperature,and analyzes the law of overlying rock movement and stress distribution in the first mining face of Niangmute.The results show that the temperature distribution of the permafrost layer on the working face is affected by the burial depth.The temperature change of the seasonal tectonics is influenced by the seasonal temperature.With the depth increasing,the temperature distribution of the permafrost in summer and winter is consistent,the temperature gradient of winter permafrost is about 0.1?/m,and the temperature gradient of permafrost is about 0.16?/m.The physical and mechanical properties of permafrost are also changed with temperature,which is linearly related to temperature.Based on the theoretical calculation and analysis,the relationship between the fracture step and the temperature of the overlying permafrost is obtained,and the energy impact of the overburden is observed when the permafrost is broken,the resulting bending energy index is related to the permafrost temperature.By establishing a numerical model,The results show that the displacement distribution of the surrounding rock after the mining of the first mining face is the asymmetric distribution of the belt,and the deformation of the working face will cause the deformation and failure of the surrounding rock,the height of the permafrost layer is 1.6 m in winter and 1.38m in winter.The amount of sediment in the permafrost increases linearly with the increase of mining area.The larger the mining range,the more severe the impact of the permafrost on the surface,with the advance of the face,the old roof to press the first step to 22.49m,the cycle to press the footsteps of 14.4m,the permafrost will continue to sink,the range will gradually expand,When the mining area reaches a certain extent,the permafrost will break and the whole sink,which can cause the roof control problem.The results of the study are of great significance to the actual production of Niangmute coal mine.