Application of Circular Retaining Structure in Shoring Deep Soft Clay Excavation

摘要

Deep soil mixing (DSM) has been widely used in the design of excavation supports. This paper introduces a circular retaining structure using DSM to shore a deep soft clay excavation. The diameter of circular excavation is 42.117 m and the depth of the excavation is 10.7 m. The geology of the site comprises fill (3-4 m), soft clay (12-22 m) and silty clay (12-23m). The circular retaining structure is formed by nine rows of DSM columns. The DSM columns have a diameter of 550 mm and are overlapped with a minimum length of 150mm in both tangential and radial directions. In order to increase the whole rigidity of the circular retaining structure, another row of minipiles are inserted into the fourth row of DSM columns. Field monitoring data shows such circular retaining structure functions well during and after the excavation. Compared with other shoring systems, such circular retaining structure is more economical.