Abstract: Water inflow is a key parameter in the design and construction of tunnels having excess water. According to survey information from the Dahuofang water conveyance project, a three-dimensional numerical model was constructed to simulate actual conditions, and coupled fluid-solid theory was used for analysis. At the same time, FISH function in FLAC3D was utilized to calculate the maximum water inflow and normal water inflow between sections 15+720 and 15+797. Flow velocity and potential for water-related calamity was greater in the frontage of the fault construction. Forecasted water inflow was correlated well with actual survey values. Therefore, it was recommended that during the construction process detection of frontage groundwater could be strengthened along with the timely use of grout to plug excess water flow.