Analysis of Numerical Simulation on the Stability of Surrounding Rock and Support System by NATM

In the new austrian tunnel method, rational determination of supporting structures, supporting parameter and supporting opportunity, has significance to ensuring the safety and economy of tunnel construction. Stability analysis of surrounding rock and support system by numerical simulation method can provide a reference and instruction for construction and design.This paper analyses surrounding rock and support system by using three-dimensional finite difference method. The supporting structures and surrounding rock is regarded as a united mechanics, and the different supporting opportunity of supporting structures is considered. The supporting structures such as steel arch centering, systematic bolts, shotcrete and bottom concrete are simulated by structural elements. It makes detailed analysis on the change law of surrounding rock deformation, plastic zone size, stress field distribution, the force of cables, steel arch centering and shotcrete, when the system bolt length, steel arch centering model, shotcrete thickness and shotcrete supporting opportunity change, which can provide a basis for optimizing support parameters, improving the stability of surrounding rock and support system. At last, this paper analyze the monitor data of convergence measure using regression analysis, the optimal regression function is determined and the numerical simulation results are compared with the monitor data.