Face failure mechanism of fault tunnels under high-temperature and high-pressure conditions using the discrete element method

Abstract

The study of high ground stress, high ground temperature and adverse geological formations during deep-buried mountain tunnel construction holds substantial theoretical and practical significance. The failure process and mechanism of the fault tunnel face under high-temperature and high-pressure conditions are investigated through the discrete element method considering the thermo-mechanical coupling model. Initially, this method is validated by simulating the steady-state heat conduction and thermal cracking process of the disk with a hole. Subsequently, the effects of different high temperatures on the mass of gravel rushing into the tunnel, the expansion rate and rang of the fault failure zone are discussed. Finally, the micromechanical characteristics, including the magnitude and orientations of contact forces within the fault, are analyzed. The results indicate that with the increase of temperature, the mass of gravel rushing into the tunnel increases, and the expansion rate and range of fault failure zone increase. Under high-temperature and high-pressure conditions, the contact forces within the fault are strengthened, and the reinforcing effect of the pressure arch becomes more pronounced. For deep-buried mountain tunnel projects, particularly those intersecting faults, it is imperative to focus on the risk of inrush hazards posed by fault gravel in tunnel sections with high ground temperature.