Abstract: Soldier pile with strut bracing is one of the most widely used deep excavation support method in the engineering practice. In densely populated urban area with tight land use restrictions for the developments, the stress acting on the proposed deep excavation supporting structures are usually unsymmetrical. This paper presents a case history of the evaluation of the asymmetric deformation in a Chakeng cut and cover tunnel deep excavation supporting structure for the GuangzhouFoshanJiangmen Rapid Pass Project. Factors that inducing the asymmetric deformation are evaluated throughout the construction monitoring data. A threedimensional finite element model was established for simulating the stress and deformation of the excavation supporting structures. The results indicate that, in soft soils, the active lateral earth pressures are close to the passive lateral earth pressures so that the supporting structures are very sensitive to the external asymmetric loading. The soil improvement such as, soilcement mixed columns inside the excavated area could effectively reduce the lateral deformation of the supporting structures.

Key words: excavation supporting structures, strut and bracing structure, asymmetric deformation, earth pressures, finite element model