Abstract: Different types of supporting structures in the deep excavation projects often exhibit different behaviors even under the same engineering conditions. This paper presents a comprehensive pipe gallery deep excavation project in Taicang. This article compares three types of supporting structures: cast-in-place concrete piles, steel sheet piles, and Soil Mixing Wall columns. Through analysis of the vertical displacement of the top of the deep excavation supporting structures, the deep horizontal level of the support piles, and the settlement results of the surrounding ground surface, it is found that the deformation analysis of the SMW retaining structures and the cast-in-place concrete piles are basically the same. The SMW retaining structures have lower stiffness than the drilled cast-in-place concrete piles, and the deformation of the pile shaft is relatively larger. The Larson steel sheet piles perform the worst under the current excavation depth conditions. In terms of the impact on the surrounding environment, the SMW retaining structures have a smaller impact than that of the cast-in-place concrete piles. At the same time, due to the limitations such as the on-site construction conditions, time span factors have a certain impact on this observation. The Larson steel sheet piles have reached the limit of the retaining soil under the current weak soil conditions, and the settlement change of the surrounding soil has undergone a sudden change during the observation period, which has the greatest impact on the surrounding environment. In terms of the vertical displacement at the top of the pile, the three types of supporting structures perform similarly.

Key words: Deep Excavation Engineering, Support Structure, Deformation Disturbance, Comparative Analysis