关键词: 深厚软土, 单支点结构, 长短桩组合

Abstract: During the stability analysis of a single point support structure in thick, soft soils, the length to the point of fixity of the supporting pile often reaches 2~3 times of the excavation depth. This leads to a high cost of the engineering supporting pile system. Based on the current analysis method of the stress and deformation of the supporting structure for the deep excavation, a new analytical method is proposed in this paper. By investigating the characteristic of the internal force and the deformation for the different spacing of the long and short pile structure, it is proposed that the length of the long pile should be determined according to the overall stability of the support system, while the length of the short pile should be determined according to the length of effective bending moment. Comparing the bending moment and the deformation diagram of the long and short piles, the length of long and short piles can be further optimized. To verify the proposed analytical method, a three-dimensional numerical model is established to analyze the overall displacement and the internal force of the long and short piles. The effectiveness of this model is further applied and verified in a deep excavation project in Guangzhou. The proposed model can be used for deep excavation projects in deep soft ground.

Key words: Thick Soft Soils, Single Point Support Structure, Long and Short Pile Combination System