Stress Evolution Law And Optimum Arrangement Of Surrounding Rock In Middle Roadway Of Mining Face Stress Evolution Law And Optimum Arrangement Of Surrounding Rock In Middle Roadway Of Mining Face

By means of theoretical analysis,numerical simulation and engineering verification,this paper studies the evolutionary law of mining stress in the middle roadway of working face,modifies the mechanical model of stress field in the middle roadway by statistical method,and studies the stress evolution,surrounding rock deformation and the distribution law of mine quake in the middle roadway of working face in the process of mining combined with numerical simulation,mine quake location and CT inversion method,and puts forward the law of reduction.Principle of optimum layout of middle roadway for stress concentration in low surrounding rock and stability improvement of surrounding rock.The following results have been achieved:(1)The mechanical model of stress field in the middle roadway is established,and the distribution characteristics of abutment pressure of coal and rock mass in the middle roadway are obtained.The abutment pressure of surrounding rock on both sides of the middle roadway decreases with the increase of the angle between the middle roadway and the mining roadway,and the smaller the width of coal and rock mass between the middle roadway and the mining roadway(closer to the crossing position of the roadway),the higher the stress of surrounding rock mass,the wider the width of coal and rock mass(far from the crossing position of the roadway),the smaller the stress of surrounding rock mass.(2)When the angle between the middle roadway and the mining roadway is acute,the peak value of the advance abutment pressure and the maximum vertical stress,the Middle stress concentration area and the high stress concentration area in the crossing area of the working face increase with the increase of the angle of the middle roadway;when the angle is blunt,the peak value of the advance abutment pressure of the working face and the maximum vertical stress in the crossing area of the roadway,the Middle stress concentration area and the high stress concentration area increase with the increase of the angle of the The angle of middle roadway increases and decreases.The vertical stress of the middle roadway is the smallest when it is 135 degrees,the deformation of the roof and floor of the middle roadway is the smallest when it is 45 degrees,and the volume of the plastic failure zone of the coal and rock mass of the middle roadway is the smallest when it is 150 degrees,but the difference between the middle roadway and the 135 degrees is small.Therefore,when the middle roadway and the mining roadway are 135 degrees,the surrounding rock in the intersection area is the most stable.The change of the angle between the inclination of working face and the middle roadway has little influence on the peak value of vertical stress in working face,but has great influence on the Middle stress concentration area and the high stress concentration area in working face.The bigger the inclination angle between the middle roadway and the working face is,the smaller the vertical stress on the side of the middle roadway is.When the angle between working face inclination and middle roadway is 45-90 degrees and the distance between working face and middle roadway is more than 200 meters,the peak value of advance abutment pressure decreases with the increase of angle,and increases with the increase of angle when it is less than 200 meters;when the angle between working face inclination and middle roadway is 0-45 degrees,the peak value of advance abutment pressure increases with the increase of angle,while the shear plastic zone of working face increases with the increase of angle.The change is small.Therefore,when the angle between the working face inclination and the middle roadway is 90 degrees,the disturbance to the middle roadway is the smallest.(3)The non-linear regression model is established by using statistical principle,and the theoretical model of stress field in the middle roadway is modified.The regression model of lateral stress field in the goaf and the regression model of stress field in the middle roadway are obtained.The distribution of abutment pressure in the working face is calculated and predicted,and the results of numerical simulation are used to verify the model.It can be seen that the fitting effect of stress distribution curve of the whole middle roadway is good,and the linear relationship of regression equation is significant,but the square sum of residual error of regression model in the intersection area between the middle roadway and the gob-side roadway is low,and the fitting effect is poor.(4)Based on the analysis of the distribution regularity of mine shocks at the beginning of 200 m from the middle roadway in the working face,it is concluded that the total frequency of mine shocks increases with the decrease of the distance between the working face and the middle roadway.In the process of mining approaching the middle roadway in the working face,the number of mine shocks increases more and more,the frequency of large energy mine shocks increases gradually,and the distribution of mine shocks in the mining roadway area within 100 m of the advanced working face is As the working face approaches the middle roadway,the mine shocks in the intersection area between the middle roadway and the mining roadway become more and more intensive,which is consistent with the distribution law of the high stress concentration area obtained by numerical simulation.It shows that the stress concentration degree of the intersection area between the middle roadway and the track along the roadway increases with the advancing of the working face.(5)The stress distribution and evolution of surrounding rock are calculated by seismic wave CT inversion method,and the variation laws of wave velocity,wave velocity gradient and stress concentration coefficient are obtained.It can be seen that when the working face is close to the middle roadway,the velocity,velocity gradient variation coefficient and stress concentration coefficient of the crossing area of the mining roadway and roadway 100 m ahead of the working face are high.When the working face is mined to the middle roadway,the wave velocity value,wave velocity gradient variation coefficient and stress concentration coefficient of surrounding rock on both sides of the middle roadway reach the maximum,which indicates that the distance between the working face and the middle roadway is an important factor affecting the stress of coal and rock around the middle roadway,and the closer the distance is,the greater the influence is.