Performance of a Deep Excavation Constructed Using the United Method: Bottom-Up Method in the Main Building Part and Top-Down Method in the Annex Building Part

Abstract

This paper presents a case history of a deep excavation for a building foundation in soft deposit in Shanghai. This deep excavation is of particular interest because it was constructed using the united methods: bottom-up method in the main building part and top-down method in the annex building part. The excavated area is about 7000 square meters. The depth of excavation in the main building part is 13.5 m and in the annex building part is 12.0 m. The excavation was retained by diaphragm wall with a thickness of 0.8 m. Three levels of reinforced concrete bracing structures were installed to support the wall at the part which was constructed by bottom-up method. Wall displacement, axial forces of the struts, and displacements of the props were monitored during the excavation. At last, field monitored results were analyzed in details.