Abstract：The main underground structure of a certain square project in Shanghai has two stories. The area of the foundation pit is more than 20 000 m2，and the depth is 13.38 m. The construction of foundation pit adopts the method of slope associating with mid-island excavation and inverse method with circularity soleplate around. The monitoring results of stability and influence of environment show that，not only can such method of construction and design ensure stability of pit，but also shorten period of construction and decrease impact on the environment around. So the method applied in the project will be taken as an example for large foundation pit in soft soil.
