In June 2002, a 32-storey high quality commercial building with a 3-level deep basement, namely Chater House, was completed. The Chater House site was previously occupied by the Swire House and its basement structure and foundations obstructed the construction of the new basement. Temporary pipe pile walls with grout curtain were used to facilitate local trimming/demolition of the existing basement slab and pile caps. Diaphragm walls were constructed through the locally demolished basement to retain the soils for the 15m deep excavation and the new basement was constructed by top-down construction method. In addition, the diaphragm walls and large diameter bored piles were constructed to support the vertical loads and wind shear from the superstructure. This paper describes the geotechnical design aspects of the new development. The difficulties and special issues during the substructure construction works are also discussed. Instrumentation monitoring results are also reviewed and compared with the predicted movements
