Abstract: Construction in water-rich and soft soil areas usually faces dual problems of susceptible for disturbance and confined water. The Hexi area in Nanjing is a typical water-rich and soft soil area. In recent years, the development intensity has been relatively high and the area along the subway tunnel is the first choice for geotechnical engineering. However, this is often faced with the characteristics of deep, large and close foundation pits. Determining reliable subway tunnel protection measures has become an issue that needs urgent research. This article addeses this issue by taking the third phase of Nanjing Zixin Zhonghua Square as an example. Protection measures such as increasing support stiffness, soil reinforcement, and isolation piles are used to reduce the impacts of foundation pit excavation on adjacent tunnels. In the meantime, MADIS software is used to analyze the importance of relevant protection measures. The nature and necessity are verified by combining with the subway tunnel monitoring data to provide a reference for formulating protective measures for the impacts of foundation pit construction in water-rich and soft soil layers on adjacent subway tunnels.

Key words: water rich soft soil, subway tunnels, protective measures, foundation pit