Application of center-island retaining method to an excavation

They are two ways to add supports to retaining structure, and they are struts and anchors which have their own features and ranges of application. The center-island retaining method can be used, in case the anchors cannot be used and it is not economical if the struts are used. An excavation is 19.11 m deep, and there is a 16-storeys building 6 m to its east. The center-island retaining method is used in order to keep both the excavation stable and the building safe. At first, the earth is excavated with a slope at this part, so the reserved terrace can keep the retaining structure stable and control the additional deformation of the building in allowable range. The major structure is built after earth excavation is finished. The secondary excavation does not start until the major structure is built to ground surface, and three layers of struts and one layer of anchors are set in order to excavate the terrace. In the process of the excavation construction, both the displacement of retaining structure and the settlement of the building are monitored, and both of them are less than the allowable value. The engineering practice illustrates that it is successful to use the center-island method for this excavation.