Researchon Stability Of Water Conveyance Tunnel Influenced By NO.4^-2 Coal Seam Mining In Liang Shuijing Coal Mine

The water conveyance tunnel in Shenmu city is located in the northwest of the two plate area of the Liang Shuijing coal mine on the plane,The vertical distance is 19m from 4-2 coal floor.However,it is very important that the pressure damage zone of the bottom plate formed after coal seam mining will communicate with the water tunnel,causing the collapse of the water tunnel and the occurrence of water leakage.In order to ensure the safety of the water transport tunnel and improve the recovery rate of 4’2 coal in the two plate area,so it is of great significance that the study of the 4-2 coal seam mining for the stability of the water transport tunnel.Taking the Liang Shuijing coal mine as the research object,combined with the method of theoretical analysis and numerical simulation,the stability of the water conveyance tunnel is studied due to the effect of mining when the 4-2 coal seam is mining.The failure depth of coal seam floor is considered as the key parameter in theory analysis,the main roadway of 4-2 coal mining is arranged in the 4-2 coal seam,the depth of calculating 4-2 coal mining floor damage alleys is between 4.17 m to 5.02 m by the pressure arch and equivalent circle,at the same time,using the theory of plasticity and empirical formula was carried out on the floor damage depth of theoretical analysis and calculation,the damage depth of the bottom plate obtained by applying plasticity theory is 19.4m,and the damage depth of the bottom plate obtained by the empirical formula is 16.1～20.1m.The numerical simulation of the fourth chapter shows that:The maximum iMPact depth of the plastic zone is 14.5m when the working face is perpendicular to the layout of the tunnel,less than the vertical distance 19m between 4-2 coal seam floor and tunnel.Through the analysis of the vertical stress and the maximum principal stress,when the working face is continuously propelled,it is more obvious that the nearer strata from the coal seam floor are affected by the mining,However,with the increase of the depth of,the stress attenuation is faster,and the pressure around the tunnel is mainly the load of the tunnel surrounding rock.Through the analysis of the vertical displacement,the maximum displacement of the rock mass around the tunnel is only 2.5cm with the advancing of the working face.According to the analysis of 12 measuring points arranged in the lower layer of coal seam floor,it is known that when the working face is advancing,the abutment pressure of the floor increases first and then decreases,The pressure in the rock mass around the tunnel is basically the original rock stress.When working face layout direction is not same in chapter v,according to the working face advance when the plastic zone of the stope and the maximum principal stress analysis,two kinds of arrangement under the influence of plastic zone depth of 15 m or so,the stress variation in the tunnel surrounding rock affected by mining is small,so the arrangement of working face will not affect the stability of the tunnel.The research results of the paper have guiding significance for the 4-2 coal mining to the Liang Shuijing Coal mine,there is also good reference for other similar mining conditions coal mine.