Simulation of water-mud-inrush in fault fracture zone of deep and long railway tunnel in mountain area

Water-mud-inrush disasters usually happened since the tunnel went through the water-rich fault fracture area, and few simulation method concentrated on this application background. This paper comprehensively construct a fluid-solid coupling model to simulate the whole process of tunnel excavation, while the theoretical analysis, similar simulation test and numerical simulation methods have been used based on the practical of A certain tunnel. It is found that the vertical displacement of the vault increases with the excavation, and the horizontal displacement of the arch ring continues to increase when the tunnel face approaches the monitoring section. The stress of the arch crown is concentrated in the arch wall, wall foot and fault corner, and the stress change trend of the right arch ring is different from that of other areas, which is a high incidence area of water inrush. When tunneling through a fault, the maximum pore water pressure at the tunnel face continues to increase as the face advances within a distance of 5 m from the fault. The ascending gradient gradually rises until the tunnel excavation reaches the fault, at which point it reaches its maximum value. This study elucidates the evolution laws and key characteristics of water and mud inrush in fault fracture zones. The research findings can enhance the ability to identify, prevent, and control such disasters, providing a theoretical basis for disaster prevention and control.