Optimization design and practice of suspended TRD waterproof curtain for groundwater control in deep foundation pit

The Yangtze River floodplain area is rich in groundwater, has high confined water head, and thick Quaternary sedimentary strata. For deep and large foundation pits surrounding significant sensitive structures, the conventional method is to use bottom-sealing continuous walls for complete water cutoff, which is very difficulty and costly. Based on the deep foundation pit project of Nanjing Yangtze River Smart Center along the river, detailed hydrogeological parameters of the site were obtained through on-site pumping tests by using formula method calculation and numerical method fitting respectively. By establishing a three-dimensional seepage numerical model, a reasonable groundwater control scheme for the suspended water-stop curtain was optimized and determined. The impact of suspended water-stop curtain foundation pit dewatering on subways and tunnels under different foundation pit conditions was predicted. The numerical simulation prediction results were basically consistent with the monitoring data. The implementation effect and monitoring data of foundation pit engineering show that the adopted groundwater control scheme effectively protects the surrounding environment of subways, tunnels, etc. Compared with the full cut-off scheme of underground continuous walls, it reduces the project cost and better balances the impact of the surrounding environment and social and economic benefits. It can provide a reference for groundwater control in deep and large foundation pits in similar complex environments.