Experimental Study on Joint Seepage Monitoring of Underground Diaphragm Wall in Foundation Pit

The joint of underground diaphragm wall of foundation pit is prone to water seepage, which may cause great safety accidents if it is not treated in time.In this paper, a monitoring method of joint seepage of underground diaphragm wall in foundation pit was proposed.Firstly, the influence of temperature and seepage cycle times on monitoring results was studied through indoor simulation test, and then the field test was carried out based on a deep foundation pit project of a subway station to verify the effectiveness of the monitoring method.The test results show that the water seepage monitoring system can accurately determine the water seepage situation at different positions under normal temperature conditions, and the positioning error is less than 0.15 m. With the increase of the number of seepage cycles, the deviation between the calculated seepage position and the actual seepage position increases slowly, but the maximum positioning deviation is still less than 0.2m.The method in this paper is suitable for joint seepage monitoring of underground continuous wall of deep foundation pit in high water level area, and can realize real-time safety monitoring and early warning of seepage of retaining structure of deep foundation pit.