Abstract: Case history of a deep excavation project for a building construction at the north side of Suzhou Subway No. 4 Line is presented in this paper. The impact of the deep excavation process on the shielded subway tunnels was numerically simulated by using Midas GTS finite element method. The results indicated that: the maximum lateral deflection on the supporting structure of the deep excavation on the shielded subway tunnel was observed when the foundation excavation reached its maximum depth, and the lateral deflections on the supporting structures were gradually reduced during the backfill operation of the excavated area. The maximum vertical settlement in the shielded subway tunnel was 1.51 mm with a maximum lateral deflection in the tunnel was 6.32 mm; the maximum ground subsidence observed the deep excavation was 2.5 mm and the maximum ground heave at the bottom of the excavated area was 20.3 mm. The deformation and the stress within the supporting structures were satisfactory.

Key words: building foundation pits, excavation near existing structures, shielded tunnels, impact analysis