Abstract:

The structural design scheme for superdeep foundation pit with highpressure water adjacent to Minjiang River in Fujian is introduced by taking ventilation shaft on Houting StationJuyuanzhou Station Section of Fuzhou Metro Line No. 2 for example. The stress and deformation, excavation scheme and construction procedure of the foundation pit are analyzed by numerical simulation method and site monitoring method. The theoretical analysis and monitoring results show that: (1) For the foundation pit with large excavation depth and thick artesian aquifer, the excavation method combining water insulation excavation method and underwater excavation method can be adopted; by adopting underwater excavation method, the water inrush of foundation can be prevented and the stress and deformation of the structure can be improved. (2) The tension and twisting conditions of support structure under underwater excavation condition should be paid more attention to. (3) The base sealing plain concrete plate is an important resistance to large artesian pressure, which is the key to successful completion of the project and whose stress behavior mainly shows bending and shearing.

Key words: metro, interval ventilation shaft, deep foundation pit, highpressure water, stress and deformation of support structure, underwater excavation, underwater sealing