## 1 Introduction
The above research results have strongly promoted the research on the surrounding rock failure and sudden water inrush mechanism in tunnels near water-bearing faults, and greatly advanced the progress of the key theories on the mechanism and prevention of sudden water inrush disasters in tunnels approaching fault. The instability of the protective layer at the tunnel working face and the determination of the minimum safe thickness of the anti-burst body are the fundamental basis for establishing the theoretical criteria for the instability and sudden water inrush at the tunnel working face near water-bearing faults [12; 13; 14; 15; 16]. This can also provide the basis for implementing targeted comprehensive prevention and control measures to manage the occurrence of sudden water inrush disasters. In this regard, [PERSON] et al. [17] developed a three-dimensional geological model experimental system and conducted experimental studies on the evolution of displacement, seepage pressure, and the mass of the outburst material during the process of sudden water and mud inrush in tunnels under the influence of the fault fracture zone. [PERSON] et al. [18] independently developed an indoor experimental system that considers mass migration, and conducted permeability and erosion-induced sudden water and mud inrush experiments under different Talbot indices, investigating the influence of particle loss on the porosity, permeability, and water stability of completely weathered granite. [PERSON] et al. [19] used a self-developed experimental system to conduct sudden water and mud inrush experiments in the fault fracture zone under different water pressure, clay content, and sample dry density conditions, analyzing the variation patterns of the gushing water volume, porosity, and permeability during the process of sudden water and mud inrush. [PERSON] et al. [20] used a numerical simulation method to investigate the influence of fault dip angle on the stability of tunnel surrounding rock under orthogonal and parallel faults, revealing the influence law of fault dip angle on the tunnel's sudden water and mud inrush. [PERSON] et al. [21] established a fault zone and tunnel model using FLAC3D 3.00 and simulated the excavation of the Xiamen Haicang Tunnel, and analyzed the characteristics of surrounding rock stress and strain under different support methods. The aforementioned studies have achieved a series of important research results, greatly promoting the research on the mechanism of sudden water inrush in tunnels near water-bearing faults and the technological progress in the prevention and control of sudden water inrush disasters in fault tunnels. However, most scholars in the study of the influence of faults on the law of sudden water inrush in tunnel surrounding rock typically consider the fault activation and the formation of water-conducting channels under the influence of tunnel excavation at a single water pressure strength [22; 23; 24; 25; 26]. There is less research on the influence of fault water pressure on the law of tunnel sudden water inrush. In the actual construction process, the geological environment around the tunnel is highly complex, and the water pressure acting on the surrounding rock is not uniform. The mechanism of sudden water inrush in fault zones and the corresponding prevention and control countermeasures make it difficult to reach a consensus. In view of this, in order to further study the influence of fault water pressure on tunnel construction, this paper takes the instability and sudden water inrush of the tunnel working face near water-bearing faults as the research object, and adopts the three-dimensional discrete element method to analyze the evolution law of the displacement field and seepage pressure field under different fault water pressures during the process of sudden water inrush at the tunnel working face. In addition, the prevention and control measures for sudden water inrush disasters in tunnels near water-bearing faults are also explored.