Abstract: This paper presents a case history of the deep excavation support for a 13 stories high building. The deformation and stress in the supporting structure using plane strain numerical analysis method is utilized to simulate soil nail wall with prestressed ground anchor for deep excavation. The numerical analysis results are compared with the construction monitoring data and the feasibility of the supporting structure is validated. The results indicate that, the deformation of excavated area can be effectively constrained by the support structure combining the soil nails and prestressed ground anchors. The horizontal deformation of the surface near the edge of the excavation is 45 % of that when the excavated area having no support. This effectively ensures the safety of excavated area. The pre-stressed ground anchor is the major loading carrying structure when the foundation is excavated, and the maximum internal stress is about 97 kN. Under the effect of the prestressed ground anchor, the excavated surface can be divided by two areas, in the upper area, the deformation is relatively small, and the deformation is fast converged, whereas in the lower area, the deformation is relatively large, and the deformation is slowly converged. Under the effect of the pre-stressed ground anchor, the horizontal deformation of the excavated surface in the upper area is merely 25~50% of that of the lower area.

Key words: Deep Excavation, Deformation Control, Soil Nails, Prestressed Ground Anchor, Numerical Simulation