In order to study the development height of the water-conducting fracture zone in a fully mechanized top coal caving face. The E2311 working face of Gaohe Coal Mine was chosen as the research object, and the combined-strata structure and the rock layer synergistic movement mechanism were determined by combining engineering geological investigation and theoretical analysis. The height of the water-conducting fracture zone at the working face was calculated based on the combined-strata structure, and then the theoretical results were verified by numerical simulation and field measurement. The results show that after the coal seam is extracted from the working face, the movement of the overlying rock layers is in the form of bending and sinking movement of the rock layer group as a unit. Each rock layer group is controlled by a supportive lower layer with greater thickness and strength, driving the upper layers of weaker rock layers to synchronize and coordinate the movement; the sinking curvature is the same, after the lowermost support layer is bent and broken, its overlying weaker rock layers will move and break at the same time. The height of the water-conducting fracture zone of the working face were obtained by theoretical calculation, numerical simulation, and field measurements, which are 83.82 m, 84.3 m, and 86.6 m, respectively. The results are nearly consistent, thus the prediction of the height of the water-conducting fracture zone under the combined-strata structure is more accurate.

In order to study the local deformation of an anchor bolt and the improvement in the shear strength of a structural surface under the misalignment of an anchorage structure surface, FLAC^3D software was used to simulate granite, sandstone, and coal specimens with anchorage angles of 90° to analyze the damage of the anchoring agent and the changes in the local axial and shear forces of the anchor bolts with the misalignment of the structural surface. The results show that the anchor bolt near the structural surface had significant local characteristics with the misalignment of the structural surface; that is, the length of the local deformation area of the bolt was approximately equal to the length of the damaged area of the anchoring agent, and the stress on the anchor bolt was in a coupled tensile–shear stress state when the bolt reached the yield state. For the fully grouted bolts, it was this significant local feature that made the shear strength of the structural surface increase rapidly under a small shear displacement so that the structural surface reached a stable state. The improvement in the shear strength of the anchoring structural surface was caused by the misalignment of the structural surface. This is referred to as the passive improvement of the shear strength of the anchoring structural surface, which is the mechanism of the bonding section anchor to control the shear displacement of the structural surface and realize the stability of the rock mass.