Abstract: The safe and economical deep excavation supporting structure types in thick and soft soils are drawing increasingly concern by the practical engineers. This paper presents the design, analytical methods, construction monitoring aspects using both long and short piles in a deep excavation supporting project in Guangzhou. The results show that: (1) It is difficult to control the horizontal deformation of cantilever soldier piles top in soft soils, and it is a very effective measure to control the horizontal deformation of the soldier pile top by means of passive zone reinforcement from the bottom of the support beam. (2) when the excavated bottom is in the soft soils, and the excavated area must be supported by rows of piles and internal bracing, the spacing arrangement of both long and short piles is an effective optimization measure when other aspects cannot be optimized. (3) when both the long and short piles are used in the deep excavation support, the simplified model of “Considering only the action of long piles to analysis the overall stability and considering the reinforcement of the short piles and long piles together to evaluate the overall stability” can be adopted, the analytical models can be applied to the practical engineering and have achieved satisfactory results.

Key words: Deep Soft Soil, Deep Excavation Support, Spacing Arrangement of Both Long and Short Piles, Analytical Models