Deformation mechanism and control technology of coal roadway under deep well and compound roof

According to large deformation problems of compound-roof coal roadway under high stress, Qujiang Coal Mine in Jiangxi Province is taken as an example, and field survey, theoretical analysis and industrial test are performed. At first, the field survey shows that the mine has features of a typical three-high mine. Because the top anchors and side cables can be brought into full play, the whole supporting system of roadway loses balance and fails. Then, the mechanical function of the coal roadway is studied. It is concluded that the mechanical function is a gradual process, its deformation power comes from roof pressure, and the large deformation of floor is an important failure symbol. Moreover, on the basis of stress characteristics, it is suggested that the roof should be taken as the key supporting part, its integrity should be maintained, and the self-bearing ability of strata should be improved. The comprehensive control technology with the main body of prestress truss and anchor rope and the accessory body of cable + anchor + mesh reinforcement is proposed. Practice shows that the deformation of a supported roadway by means of the comprehensive control technology is markedly improved. The monitoring indicates that the relative convergence rate of sides is less than 1.7 mm/d after 91 days, and the relative convergence rate between roof and floor is greatly reduced, with the maximum value being 297 mm and the rate being less than 1.4 mm/d. So, the whole roadway is in stable status.