Abstract
The selection of the support scheme for deep-buried and large-span chambers has been a severe problem in underground engineering. To further study the mechanical mechanism of large deformation, based on the repair engineering of the chambers of Pingdingshan No.6 mine in China, the field investigation, laboratory test, numerical simulation, and theoretical analysis were studied. The surrounding rock of the central substation chamber (CSC) and the main pumping chamber (MPC) were classified according to the rock mass rating (RMR) classification method, and the main factors affecting the stability of the surrounding rock of the chambers were revealed. A prediction model of mechanical parameters of the surrounding rock was established based on the Hoek-Brown failure criterion. Additionally, the prediction results were used in FLAC3D to further analyze the failure of the original support scheme, and the feasibility of the restoration plan was proposed. Six key points of support technology for this kind of chamber were put forward. Comprehensive support and repair scheme, including “bolt, metal mesh, shotcrete, grouting, anchor cable, and combined anchor cable,” was put forward. The engineering practice indicated that the deformation rate was less than 0.7 mm/d, which was beneficial to the long-term stability of CSC and MPC. The implementation of this restoration project can provide a reference for other similar projects.
Highlights
The formation process and stress action of the surrounding rock of the deep chambers are complex, showing the complex highly nonlinear mechanical characteristics
central substation chamber (CSC) and main pumping chamber (MPC) are located in the west of the No
CSC is a chamber for the power supply and transformation system, and MPC is a chamber for the underground drainage system
Summary
The formation process and stress action of the surrounding rock of the deep chambers are complex, showing the complex highly nonlinear mechanical characteristics. Since the deep underground rock mass is a complex geological body, it is still necessary to further study the deformation characteristics and mechanical mechanism of the underground engineering rock mass, especially the controllable coordination mechanism of the support structure, and the surrounding rock deformation needs to be systematically analyzed and researched. Based on the engineering background of CSC and MPC with a buried depth of 960 m, this paper attempts to explore the deformation mechanism of this deep and large-span chamber and put forward effective surrounding rock control technology; investigate the chamber’s geological environment, the fracture structure characteristics of the surrounding rock, and the failure of the original support scheme in the field; analyze the development of the anatomical plane of the surrounding rock statistically; and test the mineral composition, physical property, and mechanical strength of the surrounding rock in the laboratory. The targeted control countermeasures and new support technology were proposed, so as to achieve regular use within the service period, and play a reference role for other engineering construction
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