Movement Law of Overlying Strata with Loading Effect in the Large Space Structure of Deep Mines

Abstract

Under the action of high-stress field, overlying strata with load characteristics in large space structure formed by changes of working faces in deep mines intensifies the movement of the overlying strata on the working face, which may easily cause dynamic disasters at the working face. Considering the large space structure of deep mines and taking gob-side entry retaining as a breakthrough point, this study analyzes various types of overlying strata structures and their loading effects. The concept and differentiation method of deep “three layers” are introduced. The movement of the overlying strata with loading effect is analyzed by establishing a large-scale Flac3D numerical calculation model and on-site inspection. The results indicate that the “arch” structure formed by the working face shifts to the middle and rear parts of the working face under the influence of the large space structure, and the overlying strata continuously evolves upward during this process. Finally, the “arch” structures of the working face are integrated within the overlying strata to form a symmetrical structure. In the deep “three layers,” “Mk” provides the force source for normal weighing of the working face. “Mj” shifts the stress relief of the working face to the middle–rear position, which may easily cause strong strata pressure at the working face. The uniformly distributed load of “My” ensures the stress relief position at the working face. Through on-site monitoring, the disturbance range and stress of Working Face 418 with large mining height are greater than those of Working Face 416. The changes in pressure relief positions of the working face are as follows: ventilation roadway > middle > intake roadway.