Study On Law Of Mining Pressure Appearance And Relationship Between Support And Surrounding Rock In 821 Fully Mechanized Caving Face Of Yuandian No.1 Coal Mine

The existence of gangue in fully mechanized caving mining will lead to the deterioration of top coal caving and low recovery rate,which will have a serious impact on the safe and efficient production of the mine.Because the distance between81 and 82 coal seams in Yuandian No.1 Coal Mine is very close,there is a layer of dirt band with an average thickness of 1.9m.it is equivalent to the fully mechanized caving mining of thick coal seam with gangue in the combined mining.Therefore,it is necessary to systematically analyze and study the law of mine pressure behavior and the relationship between support and surrounding rock in the fully mechanized caving mining face of very close coal seam.Based on the occurrence of coal seam mining in821 fully mechanized caving face of Yuandian No.1 Coal Mine,this paper adopts the research methods of theoretical analysis,similar simulation test,numerical simulation and field monitoring.The stress model of gently inclined gangue layer under uniform load is constructed.The activity law of overlying strata after 81 and 82 coal seam mining is analyzed.The influence of different thickness of gangue on top coal caving and support load is studied.Combined with field observation data,the characteristics of mine pressure behavior in working face are obtained.The main conclusions are as follows:（1）Through the stress analysis of gently inclined coal seam with gangue,it is concluded that the thickness of top coal and gangue layer has a direct influence on the cantilever distance,but the influence of the thickness of gangue layer is more obvious.When the thickness of top coal is constant,the cantilever distance increases with the increase of the thickness of gangue layer.Through the analysis of the stiffness of the coal seam containing parting,when the stiffness of the parting is greater than that of the top coal,the parting is not easy to break,which will seriously affect the top coal caving.（2）The similar simulation test was used to study the roof activity law and stress variation characteristics of 821 fully mechanized caving face,and the dynamic evolution process of the roof during the advancing process was obtained,forming a’composite cantilever beam-masonry rock beam’structure.The characteristics of mining stress under the condition of fully mechanized caving mining in coal seam with parting are revealed.The influence range of stress gradually moves forward with the advancement of working face,and the stress shows a trend of increasing–decreasing–increasing–gradually stabilizing.（3）The numerical simulation software is used to establish the model of different thickness of gangue.The 3DEC and FLAC^3Dsimulation software are used to simulate the influence of different thickness of gangue on the top coal caving,the influence of support load and the change characteristics of surrounding rock when the thickness of top coal is constant.The simulation results show that the greater the thickness of the gangue,the greater the abutment pressure in front of the coal wall,showing the distribution characteristics of the hard coal seam,resulting in a smaller distribution range of the gangue layer and the upper top coal plastic zone,which is not conducive to the fracture of the gangue layer,and will have a certain impact on the upper top coal caving.（4）Through the analysis of the data of roadway displacement,bearing pressure in front of the working face and hydraulic support resistance in the mining process,the deformation law of roadway displacement and the characteristics of mine pressure in the working face are obtained.According to the data,The selected support can meet the support requirements of 821 working face roof and provide guarantee for safe mining of working face.Figure[70]Table[2]Reference[87]...