Mechanism Of Surrounding Rock Deformation And Failure And Control Method Research In Retracement Roadway

In the ending stage of fully-mechanized face,the retracement roadway affected by the impact of mining,easily lead to large deformation of the surrounding rock and hydraulic supports crushing accidents.This paper taken the retracement roadway of fully-mechanized face in Shennan mining area as the engineering background,by using comprehensive study method of field measurement,theoretical analysis,numerical simulation and industrial test and start from the main roof fracture form of the retracement roadway,the mechanism of deformation and failure and stress distribution of surrounding rock were studied,and proposed the control method of large deformation of surrounding rock of retracement roadway,and the main work is as follow:(1)On the basis of field monitoring in fully-mechanized face retracement roadway of Shennan mining area,studied the deformation and failure laws in time and space of retracement roadway in different coal seam.It is found that the deformation and damage range of retracement roadway surrounding rock were much larger than other mining roadway and were quite different between different coal seams.(2)According to the main roof fracture position after face and retracement roadway through,deduced the formulas for calculating the roof subsidence of different main roof failure modes by different mechanical models,analysed the influence of the factors such as fracture position of main roof,mining conditions,supporting strength and section size of retracement roadway on the roof subsidence volume and combined with field measurement data for comparative analysis.The failure mode and the plastic zone range of the coal gangs of the retracement roadway were analyzed by using the theory of compressed bar and limit equilibrium theory,these studies provided the theoretical basis for the study of the surrounding rock control and support design of retracement roadway.(3)Studied the stress evolution process of the retracement roadway in the end stage of the face by field measurement and numerical simulation.The theoretical method was used to study the distribution law of the surrounding rock stress of the retracement roadway after the face through when the main roof at different fracture positions,and deduced the vertical stress calculation formula of coal pillars with single retracement roadway and double retracement roadway.Through the field stress measurement data and theoretical formula for feedback analysis,determined the main roof fracture position of the face through the retracement roadway of each coal seam in Shennan mining area and provided the basis for the control method of the retracement roadway surrounding rock.(4)On the basis of the study on the mechanism of deformation and failure of the surrounding rock and the evolution of stress of the retracement roadway,discussed the layout of retracement roadway from the point of view of ground pressure control and proposed the method of calculating the width of protective coal pillars in double retracement roadway,analyzed mining height control,yield mining and forced roof caving and studied the influence of mining height on the roof structure and the main roof fracture position,yield mining position and the applicable conditions for forced roof caving.On this basis determined the technical measures of ground pressure control in etracement roadway.(5)Analyzed the mechanism of the support and cable in retracement roadway and proposed the support parameter design method.Achievements all above were applied in retracement roadway support design of the 15206 working face in Hong liulin Coal Mine.The original support scheme was optimized on the basis of taking ground pressure control measures and achieved the face and retracement roadway through without pressure which ensuring the face's safe and fast removing.