Abstract: To address the key issue of how the water soil barrier effect induced by adjacent existing underground structures influences the dewatering recharge process in deep excavations, this paper designs a 1:50 scaled indoor physical model test based on a metro station excavation project in Tianjin. The test simulates the coupled dewatering recharge process under a suspended waterproof curtain in a sand clay dual layer stratum. By setting different barrier effect scenarios, real time monitoring was conducted on excavation inflow, water levels, retaining structure deformation, ground settlement, earth pressure and pore-water pressure. The results indicate: (1) the barrier effect significantly alters seepage paths; increasing the depth of the existing barrier exacerbates the drawdown inside and outside the excavation during dewatering and induces kicking deformation at the bottom of the retaining wall; (2) recharge efficiency is regulated by the barrier effect; under strong barrier conditions, recharge water accumulates in the narrow channel between the station and the retaining wall, leading to a notable rise in the internal water level during high flow recharge and increasing the risk of bottom heave; (3) ground settlement exhibits a contradictory response: the barrier effect aggravates settlement during dewatering, but high flow recharge under strong barrier conditions triggers secondary settlement due to increased lateral displacement of the retaining wall; (4) the evolution of soil water pressure becomes more complex; reduced effective stress behind the wall combined with increased effective stress in front of the wall jointly intensifies the force imbalance on the retaining structure. In engineering practice, for strong barrier scenarios, high flow concentrated recharge outside the excavation should be avoided. A “staged recharge + standby dewatering inside excavation” strategy is recommended to control sudden water level changes, and enhanced anti kick design at the bottom of the retaining structure should be implemented.