Research On Support Stability And Coal Drawing Optimization Of Fully Mechanized Caving Face With Large Dip Angle In Zouzhuang Coal Mine

At present,the demand for safe and efficient mining of coal seam with large Angle is more intense.In this paper,based on the engineering geological conditions of7401 fully mechanized caving face with large dip Angle in Zouzhuang Coal Mine,the physical and mechanical parameters of coal and rock were tested,the technological parameters of coal caving were optimized and the characteristics of ore pressure were simulated.The"station-surrounding rock"mechanical model of fully mechanized caving face with large dip Angle was constructed,the influencing factors of the instability of the support were analyzed,and the critical initial support was determined.Safety technical measures for anti-skid of full-mechanized caving surface with large dip Angle,anti-skid of support and anti-flying and gangue injury of working face are put forward,and field measurement of operation state of support is carried out.The main conclusions are as follows:（1）Through field investigation and laboratory measurement of physical and mechanical parameters of coal rock mass,it is obtained that the thickness of 7₂ coal seams in 7401 working face is 0.6m～11.20m with an average of 5.36m.The thickness of coal seams varies greatly,the dip Angle of coal（rock）is 28～45°with an average of35°,the uniaxial compressive strength of coal body is 6.57MPa and the tensile strength is 0.21MPa.Top coal of 7₂ coal seam belongs to Class Ⅱ top coal,no need to artificially weaken top coal,top coal caving performance is good.7401 working face and 7₂ coal seam floor for mining,the machine mining height is 2.50m,the coal drawing height is 2.86m,stoping ratio 1:1.15.（2）Through the numerical simulation test of different drawing steps and different drawing ways designed by PFC^2D,the top coal discharge rate is 85.63%when the mining is carried out by one-mining and one-releasing,which is higher than the other two drawing steps;When the single round sequential downward coal discharge method is adopted,the top coal discharge rate is 83.52%,and the stability of the support is better than the other three coal discharge methods.It is determined that the coal cutting height of 7401 working face is 2.50m,the coal mining mode is one-way downward coal cutting mode,the coal drawing step is 0.6m,the coal drawing mode is single round sequential downward coal drawing mode.（3）By using FLAC^3D numerical simulation software,the mechanical model under the average coal seam dip Angle of 7401 working face is constructed,and the distribution characteristics of coal seam working face advance abutment pressure,the migration characteristics of stope overburden,the surrounding rock failure characteristics of stope,the lateral abutment pressure distribution characteristics of two roadway and the surrounding rock deformation and failure characteristics of roadway are simulated and analyzed.（4）Based on the theory of rock pressure,the structural characteristics of overlying strata on 7401 fully mechanized caving surface and the movement law of rock blocks in the mining process are analyzed,and the stope overlying rock structure model is established to reveal the mechanical relationship of"support-surrounding rock"under such mining conditions.Through the difference analysis of the relationship of"support-surrounding rock",it is concluded that the upper part of the support working resistance is>the middle part>the lower part of the working face.The critical initial support force was obtained by analyzing the force of the support,and the safety technology of anti-reverse and anti-slip for the equipment of fully mechanized caving face with large dip Angle was put forward.（5）Based on the analysis of the field measurement data of 7401 working face support living column travel margin,support tilt Angle,support pitch Angle and so on,it is shown that the working face support is in good running condition.By monitoring the working resistance of the working face support,it is concluded that the initial support force of the working face support is above 5317k N,which can adapt to the engineering geological conditions of the working face.After analyzing the evolution characteristics of coal stress,it is concluded that the leading abutment pressure of the working face reaches the peak value at 15.7m away from the coal wall.Figure[58]Table[16]Reference[87]...