INNOVATIVE PRE-STRESSED AND PREFABRICATED SUPPORT FOR RETAINING STRUCTURE OF DEEP FOUNDATON PIT WITH DISPLACEMENT CONTROL

Based on the measured data of the foundation pit, the work mechanism and environmental effect of innovative pre-stressed and prefabricated support(IPS) for retaining structures are studied in three aspects. They include pre-stress control, deformation control and stiffness control. Results show that: Compared with the traditional support, the passive soil pressure is fully motivated by the pre-stress that applied to the retaining structure using IPS before excavation. And the measured data shows that the overall deep displacement of the retaining structure is less than 10mm. At the same time, the IPS is applied to limit the deformation of foundation pit by applying pre-stress to improve the apparent stiffness. Measured surface subsidence is not more than 18mm which show it reduces the impact of excavation on the environment effectively. In addition, aimed at the stress concentration defect of traditional internal support, the IPS overcomes it through the support system full span reaction. The IPS indicates wide application in deep excavation engineering.