Abstract: Water and sand inrush disasters of shield tunnel in silty (fine) sand aquifer frequently occur. A Coupled Eulerian-Lagrangian (CEL) method incorporating seepage analysis, referred to as the S-CEL method is proposed to simulate the interaction between water, soil, and shield tunnel during the disaster. First, two leakage experiments are used to validate the proposed method. Subsequently, the S-CEL method is utilized to simulate the water and sand inrush process in an accident. The method is further validated by the measured data. The sequence of leakage point evolution at segment joints, as well as the soil loss mechanism and tunnel structural response mechanism associated with the evolution of leakage joints is revealed. The study shows that leakage joints progressively evolved along the longitudinal direction of the tunnel. The soil loss mass rapidly escalates, resulting in the formation of erosion void at clay-silt layer interfaces, and causing severe differential settlement, segment dislocation, and concrete damage of tunnel. Finally, the disaster rescue measures are investigated. It is suggested that after the disaster occurs, dewatering measures and temporary reinforcement measures for the tunnel should be taken as soon as possible, which can effectively delay the occurrence of subsequent leakage joints.