Abstract: The unloading-reloading conditions during an asymmetric foundation excavation usually are harmful to the underlying subway tunnel. To verify the disturbance of foundation excavation, the modified centrifugal system was used to simulate different excavation steps, and the load transfer of foundation-soil-tunnel, considering the relative position of tunnel and foundation pit. The results show ground loss due to the excavation, tunnel float and offset induced by asymmetric unload. The disturbance of first excavation step was small, and became stronger as the excavation depth increases; the left tunnel close to foundation center was disturbed more significantly. Longer distance to the foundation and tunnel generates weaker the disturbance by unload-reload. The force of tunnel lining was redistributed because of the foundation load influence after loading. The disturbance of the section lying between piles was obvious. The section lying one-sided pile was small, the disturbance of pile group effect was more obvious.

Key words: asymmetric excavation of foundation pit, subway tunnel, unload-reload, centrifugal test