Three-dimensional deformation behavior of the Taipei National Enterprise Center (TNEC) excavation case history

The Taipei National Enterprise Center (TNEC) excavation project was constructed using the top-down construction method, in which a diaphragm wall was supported by the concrete floor slab. Previous studies have reported the deformation and stress-strain behaviors along the main observation section, which was considered to be in the plane strain condition. This paper examines the three-dimensional movements of the soil and wall through field observations and finite element analyses. The results indicate that the soil outside the excavation zone tends to move toward the excavation center. Such a tendency increases with excavation depth. The soil settlement near the corner of the excavation is less than that near the center due to the corner effect. The empirical equation proposed by Clough and O'Rourke for estimating the ground settlement appears to be adequate for plane strain sections and other non-plane strain sections. Numerical studies indicate that the wall deformation and ground surface settlement can be reasonably predicted using three-dimensional finite element analysis. Parametric studies revealed that for this case record zoned excavation commencing near the final stage of excavation has very little effect on excavation behavior.Key words: TNEC case history, deep excavation, deformation, three-dimensional finite element method.