Design and practice of partitioning of deep large foundation pits close to subway in thick soft soils

Ningbo Greenland Center Project is located in thick soft soils. The area and excavation depth of the foundation pit are about 41000 m² and 15.9~18.1 m, respectively. The surrounding environment of the pit is complex, which is close to subway station, tunnels, bridge and underground lane. According to the characteristics of the project, the support structures of foundation pit are designed using the support system, which is "partitioning and making" and "retaining structures + multilayer support". In order to reduce the influences of excavation of the foundation pit on the surrounding environment, especially the subway tunnel, multiple technical measures are adopted. The partitioning of the foundation pit, steel support for axial force compensation and partitioning piles are introduced. The results of the implementation and monitoring data show that the technical measures have achieved good effectiveness, the safe and controllable is achieved goal during the entire construction process. It may provide a reference for similar projects.