The present study focuses on an area of a tunnel located in the mountainous region of southwestern China, characterized by fractures and water inrush. We analyze geological survey data from the tunnel site and conduct physical model experiments using a specially designed apparatus. These experiments investigate the effects of different conditions on the underground groundwater seepage field and the reduction coefficients of hydraulic pressure. Subsequently, we perform numerical simulations with the Groundwater Modeling System (GMS) and validate the outcomes against the model experiments. The research findings reveal significant alterations in the subsurface seepage field due to tunnel excavation, initiating groundwater flow in the fractured fault zone. After excavation, a symmetrical funnel-shaped distribution of groundwater levels is observed in the central region of the experimental model. The fluctuations in groundwater levels exhibit a greater magnitude in the vertical direction compared to the horizontal direction. The hydraulic head remains relatively constant outside the funnel-shaped area. With increasing total hydraulic head and drainage volume, the spatial extent of the seepage field's influence progressively expands. These research findings hold significant theoretical and practical value for future tunnel route selection, construction, and subsequent maintenance.