Mechanical and Deformation Properties of Deep Foundation Pit Supporting System Subjected to Asymmetric Loadings

Abstract

Due to the limitation of the terrain and environment condition, two sides of deep foundation pit often appear in different elevation level, which makes foundation pit subjected to asymmetric loadings. The mechanical characteristics of retaining structure with the influence of asymmetric loadings are quite different from that with the influence of symmetric ones. Currently, the relevant code doesn’t present a detailed method for supporting system design of foundation pit under asymmetric loading. Based on Shazitang Station of Changsha Metro Line 4, two sides of them are at different elevation level, the supporting system design scheme and the excavation process was then introduced. Especially, to ensure the safety of foundation pit as well as surrounding buildings, the first supporting was designed as concrete diagonal brace. The horizontal displacement of diaphragm walls and the settlement of surrounding buildings were monitored. Finite element models, which aimed at analyzing the stress and deformation of supporting structures, were then established. With respect to the action of asymmetric load, the horizontal displacement of diaphragm wall on the side of higher elevation level is bigger than the other side. At the top of the wall, the horizontal displacement appears to be a “drift” towards the side of lower elevation level. The horizontal displacement of diaphragm wall and settlement of surrounding ground is relative small and meets requirements of relevant code. In all stages of construction, the deep foundation pit and surrounding buildings remain safety. It can be concluded that the design of supporting system is highly effective in controlling deformation during the foundation pit excavation, which can provide a reference for the design and construction of similar projects.