Stability control strategy and application of deep pump absorbing well chamber group

Deep rock mass is in a complex mechanical environment characterized by high ground stress, high ground temperature, high karst water pressure, and strong mining disturbance, resulting in difficult support and high levels of failure in the pump chamber group. To solve the problem of the instability of the deep pump chamber group, this paper takes the −890-level pump absorbing well chamber group of the Daqiang coal mine as the engineering background. Through theoretical analysis, numerical simulation, and field tests, the reasons for the failure of the chamber group are analyzed, and the effects of intensive design and traditional design on the stability control of the surrounding rock are compared. According to the characteristics of high constant resistance, high elongation, and energy absorption of the negative Poisson’s ratio (NPR) cable, the instability energy criterion of intersection under the NPR cable support is established, where the chamber is stable at K_N ≤ 1. The intensive control strategy of the pump absorbing well with a high prestressed NPR cable and three-dimensional truss as the core is presented and applied in the field. The results show that high ground stress, low surrounding rock strength, dense chamber group distribution, unreasonable excavation sequence of the chamber group, and inappropriate support are the main reasons for the failure of the deep pump absorbing well chamber group. Compared with the traditional design, the intensive design simplifies the layout and construction procedure of the chamber by considering the absorbing well, improves the stress conditions of the chamber, reduces the displacement and stress of the roadway, makes the plastic zone range smaller and more uniform, and eliminates the spatial effect. The deformation energy of the surrounding rock is released through the high constant resistance and large deformation of the NPR cable and the reserved gap between the truss and the surrounding rock, and the deformation of the surrounding rock is limited through the application of high prestress to the NPR cable and the strength of the three-dimensional truss material, which allows for the full use of the self-bearing capacity of the surrounding rock and effectively ensures the roadway stability. The field application shows that this strategy can effectively ensure the stability of the chamber group; the deformation of the surrounding rock is controlled within 70 mm, and there is no shedding, cracking, or destruction of the sprayed layer after concrete sealing, which indicates that the technology plays an important role in controlling the stability of the deep roadway and can provide a reference for similar projects.