Abstract: Using the rehabilitation of an underwater shield-driven tunnel being damaged by sand gushing as an example, this paper introduces the technological process of the casing method and analyzes construction safety by a 3D finite-element model. The results show that: though the impact force of a hydraulic vibratory hammer has little influence on an existing tunnel, the construction process needs to be calculated and verified; and maximum deformation and stress occur at the opening of the tunnel vault, necessitating structure reinforcement and water-stop measures.