Abstract
In order to solve the problems of roadway stability and easy instability under repeated mining of close-distance coal seam groups, the mechanism and control technology of surrounding rock instability under repeated mining were studied via indoor testing, field testing, physical similarity simulation experiment, and numerical simulation. The results show that the surrounding rock of roadway has low strength, low bearing capacity, and poor self-stabilization ability, and it is vulnerable to engineering disturbances and fragmentation. Affected by the disturbance under repeated mining, the roadway surrounding rock cracks are developed and the sensitivity is strong, and it is prone to large-scale loose and destroyed. The location of the roadway is unreasonable, and the maximum principal stress of the roadway is 3.1 times of the minimum principal stress, which is quite different. Thus, under a large horizontal stress, the surrounding rock undergoes long-range expansion deformation. On the basis of this research, the direction and emphasis of stability control of roadway surrounding rock under repeated mining of coal seam groups in close-distance are shown. A repair scheme (i.e., long bolt + high-strength anchor cable + U-shaped steel + grouting) is proposed, and reduces the risk of roadway instability.
Highlights
Downward mining is the top-down mining between coal seams, and it is generally used in close-distance coal seam groups
Mining coal seams at close theseams upper will coal cause seamsawill cause a certain degree of Mining coal seams at close distance, thedistance, upper coal certain degree failure to coal the lower are completed of failure to the lower seam.coal upperThe coalupper seamscoal areseams completed as shownas inshown
In order to study the stability and control of roadway surrounding rock under reIn order to study the stability and control of roadway surrounding rock under repeated mining, this article adopts a variety of research methods including indoor rock peated mining, this article adopts a variety of research methods including indoor rock mechanics experiments, physical similar simulation test, numerical simulations, and field mechanics experiments, physical The similar simulation test,methods numerical and field measurements
Summary
Downward mining is the top-down mining between coal seams, and it is generally used in close-distance coal seam groups. The roadway surrounding rock is disturbed and destroyed repeatedly while mining the lower coal seam, which can lead to the instability and serious destruction of the roadway surrounding rock [6,7]. The deformation and destruction of the roadway surrounding rock is more prominent when mining a close-distance coal seam groups, especially for the excavation of soft rock roadways, the floor heave and sidewalls often move inward [11,12]. Studying the stability control technology of the surrounding rock of the roadway under repeated mining of the close-distance coal seam groups has important theoretical and practical significance for its safe and efficient mining
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