Research on Frame Isolation Pile to Reduce the Influence of Foundation Pit Excavation on Adjacent Tunnel

The tracking monitoring and finite element model simulation are carried out to the ancillary isolation pile project of Shi Hai tunnel of Ningbo rail transit line 1. The influence pattern of frame isolation piles on surrounding environment during foundation pit excavation is analyzed. The results show that the influence pattern of foundation pit excavation with frame isolation piles on retaining piles, soils outside the pit and adjacent tunnel are similar to those without frame isolation piles; however, the deformation value can be significantly reduced. The protective effect of frame isolation pile on adjacent tunnel during foundation pit excavation is evident.