Performance of a Large-Scale Metro Interchange Station Excavation in Shanghai Soft Clay

AbstractA 24–33-m-deep cross excavation of a metro interchange station in Shanghai soft clay has been constructed and monitored for 2 years. The excavation area was 9,000 m2 and supported by diaphragm walls. For construction convenience, the excavation was split into four zones (multiple pits) with varied sizes and depths. On the basis of the interpretation of field monitoring data, the following major findings were obtained: (1) the measured wall deflections and ground settlements were smaller compared with those of similar case histories; (2) both jet-grouting and the geometry of pit played a key role in determining pit performance; (3) the location of maximum wall deflection varied dramatically with excavation depth and displayed three patterns; (4) the measured column uplifts were closely related to excavation depth; and (5) the axial forces of most struts were within 40% of design value, indicating safe for the strut system.