Simulation of Large Span Chamber Stability: Hoek Brown and Point Safety Factor Optimization

The design of rock stability analysis and initial support is critical in the construction of super large span (SLS) chambers. Firstly, the point safety factor under the unloading stress path is derived and established using the instantaneous linearization method, based on the nonlinear Hoek Brown (HB) criterion. The calculation of the point safety factor is realized with the FISH program, and a determination method for the stability of the surrounding rock is proposed. Secondly, a procedure for optimizing the support parameters based on the point safety factor method is proposed to address the shortcomings of the initial support design for SLS chambers. The effect of different support parameters on the stability of the chamber is discussed, and the feasibility of constructing the chamber for different chamber depths, rock levels, and lateral pressure coefficients is then analyzed. A design chart has been developed for the design of a SLS chamber support structure. This research can serve as a reference for the design and construction of similar projects.