Design of supports for asymmetric extra-deep foundation pit of financial block project in Qianjiang CBD of Hangzhou

The deep foundation pit is located in Qianjiang CBD of Hangzhou City and is less than 100 m away from the Qiantang River. It's well known as the high water level and strong permeability foundation. There are four dependent high-rise towers on the ground which belong to 4 bank finacial units respectively, and a large integral basement consists of three parts, three-story basement under the towers of Huarong and ICBC (Industrial and Commercial Bank of China Limited), four-story basement under the commercial tower and five-story basement under the tower of China Zhejiang Bank Co., Ltd. The excavation depth is in the range of 17.0~24.0 m, and the maximum depth is approximately 28.5m in the core tube. In addition, the overview and features, retaining schemes, excavation process under the conditions of asynchronic construction, measures of dismantling and replacing support, analysis of the internal force and deformation caused by asymmetric excavation, treatment of deep confined water and monitoring results are introduced.