Case study of deep excavation in existing underground structure of three-story basement and diaphragm wall

摘要

In general, site size of an urban renovation case is small in Taipei. The difficulty of workabilityrnis added by the influence of the old building foundation on the to-be-constructed building foundation. This paperrnpresents a renovation case of a building project, 12-story high with a 3-story underground basement covering arearnof 583m~2 in Taipei. Perimeter of the planned site is about 80 m. The existing foundation and the diaphragm wallrnare 14.2mand 25min depth, respectively. In addition, the diaphragm wall thickness of this old building is 70 cm.rnThe new building foundation planned to set inside the existing diaphragm wall of the old building. New buildingrnis planned to excavate down to 21.5 m, with drilled shafts H414×405×18×28mm installed down to 34 m.rnThe new foundation had been constructed by incorporating with the old diaphragm wall, the new drilled shaftsrnand cylindrical soil improvement . In addition, combining the top-down and bottom-up construction proceduresrnwas used by taking advantage of the B3 slab of to-be-constructed building to connect existing diagram wall andrnthe new installed drilled shafts to complete the building project.