Abstract: Huge potential risks exist during the construction of the extralarge diameter shielded tunnels passing through the pile supported foundation of adjacent existing buildings or other structures. This paper presents a shielded tunnel construction of Changjiang Road river crossing tunnel in Shanghai. Tunnel excavation near the pile supported viaduct of Yixian Road and Rail Transit Line #3 induced risks are identified and analyzed. The Metro Jet System (MJS) was used to isolate and to strengthen the pile supported foundations adjacent to areas to be undercrossed. The design and construction parameters for the under passing the pile supported foundations were able to be adjusted by the trail excavation and construction monitoring. The deformation of the isolated foundation structures were monitored during the construction until the deformation is stabilized and meet the allowable post construction deformation criteria.

Key words: Super Large Diameter Shield, Approaching Construction, Pile Supported Bridge Foundations, Risk Analysis, Risk Management