Advanced stability analysis method for the tunnel face in jointed rock mass based on DFN-DEM

Abstract

An advanced stability analysis of surrounding rock can assure safe construction in tunnels. However, in traditional analysis methods, geometric information on the rock mass discontinuities is obtained by a geological compass and treated as an infinitely expanded plane in a numerical simulation, which is inaccurate in both geometric and numerical models. To solve this problem, this paper studied a control network and an image stitch method to assess the accuracy of a geometric model and proposed a more accurate method to obtain the geometric information of rock mass discontinuities based on digital photogrammetry. Based on discrete fracture network and discrete element method (DFN-DEM), this paper treated the rock mass discontinuities obtained by digital photogrammetry as finite disk planes and simulated the excavation process of the Qianyu tunnel. According to the simulation results, this paper determined the specific location of the collapse disaster on the tunnel face, which is of great significance to tunnel support design. Comparing the deformation of the surrounding rock mass on the tunnel face in the simulation results with the actual situation, this paper verified the feasible accuracy of this method in analysing the stability of the surrounding rock mass on a tunnel face in advance.

Keywords

• Digital photogrammetry
• Discrete element method
• Discrete fracture network
• Stability analysis