Abstract
To address the large deformation of the surrounding rock of deep gob-side entry retaining under high stress, lithological characteristics of the surrounding rock and failure model of support body and their evolutionary processes are analyzed through field investigation and theoretical analysis. Failure mechanisms of surrounding rock and the technology to control it are studied systematically. The results show that the causes of the large deformation of the surrounding rock are weak thick mudstones with softening property and water absorption behavior, as well as its fragmentation, dilatancy, and long-term creep during strong disturbance and highly centralized stress states. The cross-section shape of the roadway after deformation and failure of the surrounding rock is obviously asymmetric in both the horizontal and vertical directions. Since the original system supporting the surrounding rock is unable to completely bear the load, each part of the supporting system is destroyed one after the other. The failure sequences of the surrounding rock are as follows: (1) roadway roof fracture in the filling area, (2) filling body fracture under eccentric load, (3) rapid subsidence of the roadway roof, and (4) external crack drum and rib spalling at the solid coal side. Due to this failure sequence, the entire surrounding rock becomes unstable. A partitioned coupling support and a quaternity control technology to support the surrounding rock are proposed, in which the roof of the filling area plays a key role. The technology can improve the overall stability of gob-side entry retaining, prevent support structure instability caused by local failure of the surrounding rock, and ensure the safety and smoothness of roadways.
Highlights
The deformation of surrounding rock of gob-side entry roadways in deep and shallow coal mines is very different
A method of grading gob-side entry retaining is widely adopted by the Huainan Mining Group
A systematic investigation of the failure mechanism and control method of the surrounding rock in deep gob-side entry retaining is of practical significance for gob-side entry retaining technology in deep mines
Summary
The deformation of surrounding rock of gob-side entry roadways in deep and shallow coal mines is very different. Geofluids and suggestions for supporting surrounding rock by analyzing the deformation and failure characteristics of gob-side entry retaining of a working face with multiple roadways; Xie et al [4] presented a new method of roadside support using a concrete-filled steel tubular scaffold by investigating the settlement and failure of surrounding rock structures of gob-side entry retaining with large mining height; Han et al [5] presented a concept of roadside composite bearing and revealed the stability mechanism of roadside structures. This study illustrates the failure mechanism of the surrounding rock and proposes a quaternity control technology and roof partition coupling support to support the surrounding rock, with the filling area’s roof playing a key role. This technology is verified through field engineering to determine whether it provides a good supporting effect
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