Research And Application Of Strata Behavior Law And Reasonable Mining Height Of Large Mining Height In Deep Fully Mechanized Face In Xinan Coal Mine

Exploring the laws of mining pressure in large mining height working face under deep mining conditions and determining the reasonable mining height is of great significance to the stope management,coal wall stability control,resource recovery rate and safe and efficient production of large mining height working face.This thesis takes No.3311 large mining height fully mechanized face in Xin'an coal mine as the research background,the key strata distribution,the caving distance of overlying strata and the height of three belts are obtained through theoretical analysis the distribution of stress field and displacement field under different mining height is studied by using numerical simulation software,which provides a basis for determining reasonable mining height.Industrial experiments and on-site monitoring were carried out at No.3311 working face to verify the reliability and rationality of the study on the regularity of ground pressure behavior and the determination of rational mining height in deep mining and fully mechanized face with large mining height.The main research conclusions are as follows:(1)Based on the theoretical analysis of key strata and relevant formula calculation,it is determined that the low level sub key strata of No.3311 fully mechanized working face with large mining height are 9.9m thick medium and fine-grained sandstone,and it is the basic roof of the working face,under which the9.5m thick interbedded sand and mudstone is the direct roof;the first step of basic roof weighting is 56.97 m,and the interval of periodic weighting is 18.99-28.48m;through the calculation of overburden three zone formula,the key strata are determined The height of the three zones is as follows:H₁=18.56m,H₂=60.2m,H₃=539.8m.(2)A mechanical model is established for the basic roof block along the advancing direction of the working face,and the reasonable rated working resistance of the working face is determined to be 10505k N/frame through analysis and relevant calculation,the maximum deflection of coal wall in horizontal direction is 0.578 times of mining height,that is,upper and middle part of coal wall is easy to produce sheeting.(3)Numerical simulation results show that the stress of the advanced face increases along the advancing direction under the deep mining condition.The mining height is negatively correlated with the peak of the leading support stress,and positively correlated with the influence range of the leading support pressure;with the increase of the mining height,the height of the roof damage and collapse of the working face is increasing;when the height exceeds 6.5m,the maximum tensile stress and the affected height increase rapidly.(4)Numerical simulation results show that the increase in mining height leads to an increase in the deformation of the coal wall and the expansion of the damage range.When the mining height exceeds 6.5m,the damage range increases sharply.The scope of influence has also increased,which is not conducive to the support of advanced roadways.(5)Comprehensive analysis of geological factors,technical factors and economic benefits of No.3311 working face determines that the reasonable mining height of the working face is 6.3m,and the mining height should be adjusted reasonably according to the coal thickness,but the maximum mining height should not exceed 6.5m.At the same time,the“three machines”of the working face were selected.The MG750/1840-WD double drum shearer,the ZY13000/30/65D hydraulic support and the SGZ—1000/1400 scraper conveyor can meet the requirements of the working face.The need for safe production.(6)According to the mine pressure observation results of No.3311 working face,the basic roof weighting step is about 57.3m,the periodic weighting step is 18.9m?20.5m,with an average of 19.7m,the accuracy of the theoretical calculation is verified;the influence range of leading bearing pressure is 58m,and its violent influence range is 28m,and the average peak distance of advance abutment pressure is 13.8m the distance should be more than 30m.(7)The peak value of the lateral abutment pressure of the working face appears at 5-6m away from the edge of the adjacent goaf;the influence of the mining disturbance on the displacement of the two sides of the roadway and the roof subsidence is very small,and the influence of the mining disturbance on the deformation of the surrounding rock of the roadway within 30m away from the coal wall is great.