Pile group response induced by adjacent shield tunnelling in clay: Scale model test and numerical simulation

Abstract

The shield tunnelling adjacent pile group was a common phenomenon in urban metro construction, and additional internal force and displacement field of pile group was disadvantageous to existing superstructure. In this paper, a micro shield machine was invented to simulate the shield tunnelling process, and a series of physical scale model tests and 3-D nonlinear FE models were employed to investigate the pile group (2 × 2) response with different minimum distance between pile group and the tunnel central line (Hm) in clay. The results indicated that large additional bending moment and axial force was induced by shield tunnelling, the maximum bending moment was near the tunnel center line, and the amplitude of maximum bending moment in the lateral section (My) was three to five times of that in the longitudinal section (Mx). The maximum lateral displacement emerged at the tunnel central line, and the vertical displacement distributed uniformly along pile length. The negative shaft resistance between pile group and surrounding soil obviously reduced the axial bearing capacity. The shielding effect of the front pile on the rear pile greatly reduced its internal force and displacement, but it gradually weakened with increase of Hm. The internal force and displacement of pile group decreased quickly with increased of Hm. The research results in this paper can provide a reference for the design and construction of shield tunnels near pile group.