Analysis on Excavation Procedure in Large Soft Soil Foundation Pit of Shanghai Expo Axis
On the basis of the large soft soil foundation pit of Shanghai Expo axis and the Section 1 of underground complex project, this paper proposes the appropriate excavation procedure according to the results obtained by using centrifuge model tests and time hardening creep model, which uses ANSYS to compute foundation pit deformation caused by different excavation timeline, sequence and longitudinal excavation width of remained berm. The results of numerical calculation were approximately close to the horizontal displacement of the underground diaphragm wall measured both on site and from centrifuge model tests, so numerical calculation could well reflect the deformation behavior of excavation. The study also showed that more than 80% of underground diaphragm wall deformation caused by soil creep occurred within 60 days after the remained berm being excavated. In order to decrease the deformation, it would be useful to conduct plate structures as soon as the remained berm started being excavated. Remained berm and middle plate had good control over underground diaphragm wall deformation. When the remained berm was excavated by jumpily digging method, it would be advisable to firstly excavate the vicinity of underground diaphragm wall where there were no required protected objects nearby. The longitudinal excavation width of remained berm was proposed to be 20 meters in the north part and 30 meters in the south part.
Chaohe Chen, Yong Huang and Guangfan Li
X. Yuan et al., "Analysis on Excavation Procedure in Large Soft Soil Foundation Pit of Shanghai Expo Axis", Advanced Materials Research, Vols. 243-249, pp. 2909-2914, 2011