Vertical Movement of Pile Groups Caused by Adjacent Large Diameter Shield-Driven Tunneling in Shanghai Soft Clay: Fid-Bau Portal

Vertical Movement of Pile Groups Caused by Adjacent Large Diameter Shield-Driven Tunneling in Shanghai Soft Clay

Liu, C. / Zhang, Z. X.

This study provides a case history of a large-diameter shield tunnel (D = 15.43 m) in Shanghai soft clay through field measurement and finite element analysis (FEA). Two elevated bridges - Yixian elevated road and Metro Line 3 - were supported by multiple pile groups and multi-crossed by a large-diameter slurry shield machine. The two bridges were first crossed by the shield machine during the south-bound tunneling, and then crossed during the north-bound tunneling by the same shield machine. The minimum clearance between the shield skin and piles is 1 m. Field measurement on the movement of the pile groups during the tunneling process - including the vertical, longitudinal transverse, and lateral transverse displacement - was carried out for both bridges. The finite element (FE) software program, ABAQUS, is used to investigate the movement of the pile groups during the multi-crossing by the slurry shield. A full, three-dimensional FE model is generated without considering upper structures of the two bridges. Most of the relevant factors in tunneling are taken into consideration in the FE models, including:slurry pressure, grouting pressure, grouting material hardening and soil-pile interaction. A modified Cam clay (MCC) model is adopted in simulating the soft clay in Shanghai involved in this tunnel project. The FE results are compared with the field data to provide a better understanding of the disturbance of pile groups caused by the crossing tunneling process.