Abstract: During the deep excavation in soft soils, the exposed soil in the excavated area will experience creep effect under the earth pressures. The deflection of the supporting structure will also increase with the increase of exposed time. At the same time, the strength of the reinforced concrete strut will also increase with the increase of curation time, therefore, the capacity of deformation control of the strut will also increase. Therefore, balancing the creep time and the curation age of the reinforced inner strut has a special meaning for the deformation control of the excavation supporting structure. This paper presents a case history of a deep excavation supporting project Qianhai Station of Shenzhen near shore marine soft soils. The influence of creep in the soft soils and the curation time of the reinforced concrete on the deformation of the supporting structure and the internal force in the strut are discussed. The results indicate that, under the curation time of 28 days, if the creep effect is considered in the supporting structure, the deformation increased 13.9%, 9.3% and 5.3%. If both the curation and the creep effect are considered, each excavation has an optimized period of 12-16 days. When the excavation depth is shallow, the effects of both creep in the soft soils and the curation time in the reinforced concrete curation time should be considered. When the excavation depth is large, enough curation time in the reinforced concrete strut should be considered since the stiffness of the strut is important in this stage.

Key words: Deep Excavation, Creep in Soft Soils, Inner Strut Stiffness, Time-Dependent Effect