Study on the layout of staggered roadway and surrounding rock control technology for extremely close coal seams

In order to solve the problems of high difficulty and high risk in slicing mining of extremely close seam groups, explore the application prospect of staggeredroadway layout mining method and joint support technology of adjacent roadways between sections in the mining of extremely close seam groups,based on the research background of the geological conditions of No.8 coal and No.9 coals in Guandi Coal Mine, it has been demonstrated that the thickness of gangue layer between No.8 and No.9 coal is small, which can meet the requirements of top coal caving and will not affect the top coal caving performance. Therefore, it is determined that the combined mining scheme of extremely close coal seam with staggered roadway layout mining method is adopted.Through the limit equilibrium theory analysis and numerical simulation, the position of the lower section along the bottom roadway is determined: the width of the top coal crushing zone of the roadway along the bottom is 1.93 m, and the width of the limit equilibrium area is 6.65 m. FLAC3D numerical simulation software is used to select the position of the lower section along the bottom roadway. The calculation result shows that the distance between the peak lateral abutment pressure and the side of the roadway is 6.85 m, which is basically the same as the width of the limit equilibrium zone obtained by the foregoing theoretical calculation.Combined with the results of theoretical analysis and numerical simulation, it is determined that the horizontal stagger distance of the staggered roadway is 2 m. The technical mechanism of the joint support of adjacent roadways between sections is demonstrated and researched, and the joint support scheme of adjacent roadways between sections is finally determined based on the original support plan of the mine. The field industrial experiment is used to measure the roof and floor movement and the two sides movement of the roadway along the bottom in the lower section. The monitoring results show that the deformation of the surrounding rock of the roadway along the bottom in the lower section is generally within the controllable range, and the support scheme design of the roadway with staggered layers is more reasonable, which can meet the safety production needs of the working face, and can provide a reference for working face layout and surrounding rock control under similar conditions.