Two-Dimensional Numerical Model for Stability Analysis of Tunnel Face Based on Particle Flow Code

Abstract

In this paper, numerical simulations of face stability of shallow tunnels are carried out by using the particle discrete element codes PFC2D from the microscopic view. Progressive instability of the tunnel face is achieved through the withdrawal of the baffle used to simulate the tunnel face. Under different retreating displacement of the tunnel face, the evolution laws of support pressure on the tunnel face, the ground deformation, ground surface settlement and contact force chain in front of the tunnel face are studied. The results show that with the withdrawal of the tunnel face, the support pressure on the tunnel face can be divided into four stages, namely, the rapid decline stage, the minimum stage, the slow rising stage, and the horizontal stability stage. Moreover, based on the simulation results of the particle contact force chain, discriminated methods of failure zones are proposed. The research results obtained from this paper will provide theoretical support for the reasonable value of support pressure of a tunnel face in practical engineering.

Two‐phase model for the excavation analysis in partially saturated soft soils using the particle finite element method

“…24 Limitations of this method, however, are linked to their high computational cost as compared to other numerical procedures 25 and the complexity of the calibration procedure 24 required for the suitable identification of the relevant microscopic (inter-particle) parameters involved in the constitutive description of the material. The DEM has been applied, for example, in the numerical analysis of rock cutting processes, 23 tunnel face stability in granular soils 26,27 and tool-soil interaction in granular material. 24 On the other hand, continuum based simulation methods model the soil mixture in a smeared sense, where the quantities of interests are averaged over a representative volume and described via macroscopic variables.…”