The island-tunnel joint section of the Shenzhen-Zhongshan Link is reinforced with high-pressure jet grouting piles to form a water-stop curtain.It is hard to accurately assess the water-stop performance of the curtain through conventional core sampling tests.Based on the water level recovery test method,this study regards the island-tunnel joint section as an independent pumping well and develops a test procedure for analyzing and evaluating the permeability of anti-seepage curtains.The phreatic water level and confined water pressure are monitored by embedding water level pipes and pore water pressure gauges,and the continuous water level change data during the test are obtained to calculate the permeability coefficient of the water-stop curtain.The results show that the maximum daily water seepage of the island-tunnel joint section using high-pressure jet grouting piles as the water-stop curtain is about 169.05 m3,and the comprehensive permeability coefficient calculated via Darcy’s law is 7.03×10-6 cm/s,a value close to that of clay.The high-pressure jet grouting pile cutoff wall exhibits good water-stopping performance,which has been verified by the subsequent excavation and construction process of the foundation pit at the island-tunnel joint section.When the coring detection method is difficult to judge the pile quality,this method can be used as an effective means for evaluating the water-stop performance of the water-stop curtain.The research results have certain reference significance for the design and field in-situ detection of high-pressure jet grouting pile water-stop curtain.