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

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 loca-tion 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.

Automated summary

An advanced stability analysis of surrounding rock is crucial for ensuring safe construction in tunnels. However, traditional analysis methods inaccurately treat the geometric information of rock mass discontinuities as infinitely expanded planes in numerical simulations. In this study, a control network and image stitch method were used to improve the accuracy of a geometric model, and a more accurate method based on digital photogrammetry was proposed to obtain the geometric information of rock mass discontinuities. The simulation results confirmed the specific location of collapse disasters on the tunnel face, which is significant for tunnel support design and verified the accuracy of this method in advance stability analysis.