Influence of fracture types of main roof on the stability of surrounding rock of the gob-side coal-rock roadway in inclined coal seams and its engineering application

Due to the asymmetry and heterogeneity of surrounding rock structure, the surrounding rock of the gob-side coal-rock roadway in inclined coal seams presents more serious deformation and failure under the influence of driving and mining. To reveal the influence of different main roof fracture types on the stability of surrounding rock of the gob-side coal-rock roadway in inclined coal seams, the deformation characteristics of surrounding rock under four main roof fracture types of this kind of roadway are studied by numerical simulation. The results show that the influence degree from highest to lowest of the position of the fracture line of main roof on the surrounding rock stability of this kind of roadway is as follows: goaf, coal pillar, coal wall, top of the roadway; when the fracture line of main roof is located at the goaf, the growth rate of axial and transverse stress of the coal pillar is less than that in other cases, the vertical displacement is also the smallest, and the coal pillar deformation is within the allowable range, which can maintain the support capacity of the roof in the later stage and is the most favorable for roadway maintenance. On the basis of this research, the industrial test is carried out with return air roadway of working face 1511 of a mine in Guizhou Province as the engineering background. Through theoretical calculation and comprehensive analysis of on-site borehole detection, it is concluded that for the purpose of avoiding the fracture line of main roof being above the coal pillar and close to the roadway, the coal pillar width should be changed from 3m to 5m in the next excavation. The test results of section during driving and mining show that the maximum shrinkage rate of section is 23.3%, the maximum asymmetric deformation rate, 5.2%, and the overall uniform and coordinated deformation of roadway further verifies the reliability of the research results.