Abstract: The subway shielded tunnel usually inevitably encounters the pile foundations in the urban environment. When the piled foundations are encountered, the conventional methods are to replace the above bridge or change the subway alignment. There is less reported on the direct cutting through the piles by the shielded tunneling. This paper presents a case history of subway project in Suzhou which the existing shielded machine functions are improved, and the simulation test of shielded pile cutting is performed. The test monitored the deflection of the affected piles, the performance of cutter head, the shield tunneling parameters and the abrasion and cutting process of piled foundation in the process of cutting piled foundation under different working conditions and pile cutting modes. The trial test proves that it is feasible for EPB shielded machine to cut large diameter concrete piles in sedimentary soils, the shielded machine can meet the requirements of pile cutting in the high-water level sedimentary soil layer after the relevant improvement according to actual requirements. The test results can provide basis for the formulation of special monitoring scheme and special emergency plan for shield pile cutting, and also provide guidance for the design and construction of similar projects.

Key words: Metro, Shield Tunneling, Piled Foundation, Tests