软土基坑双排桩支护结构优化分析

为分析优化软土基坑双排桩支护结构参数，以广州市某软土基坑为背景，采用ＦＬＡＣ３Ｄ对其开挖施工过程进行了数值模拟分析，研究了围护桩排数、排距、桩长、桩刚度等对基坑桩体变形以及地表沉降的影响。数值计算结果表明:当基坑开挖深度较小时，基坑的开挖对软土基坑周边土体位移影响不大，但当基坑开挖深度由５．０ｍ增至７．５ｍ时，基坑围护桩位移则由５ｍｍ快速增长至２４ｍｍ，且其变形模型由“弓形”转换为“前倾形”；随着桩排数、排距、桩长以及桩刚度的增大，桩体位移和地表沉降将逐渐减小，但其减小的幅度会越来越小；当桩排距设置为２ｄ～４ｄ、桩长设置为２４ｍ～３２ｍ、桩刚度设置为０．５ＥＩ～１．０ＥＩ时，双排桩支护结构的性价比最高。

Optimization Analysis of Double-row Pile Retaining Structure in Soft Soil Foundation Pit

In order to optimize the double-row pile retaining structure parameters of soft soil foundation pit, FLAC3 D was used to carry out numerical simulation analysis on the construction process of a soft soil foundation pit in Guangzhou. And the effects of row number, row spacing, pile length and pile stiffness on pile deformation and surface settlement of foundation pit were analyzed. The numerical results are as follows: when the excavation depth of the foundation pit is small, the excavation of the foundation pit has little effect on the soil displacement around the soft soil foundation pit, but when the excavation depth of the foundation pit is increased from 5 m to 7.5 m, the displacement of the foundation pit retaining pile is rapidly increased from 5 mm to 24 mm, and its deformation model is converted from "bow" to "forwardly inclined". With the increase of pile row number, row spacing, pile length and pile stiffness, pile displacement and surface settlement will gradually decrease, but the reduction will be smaller and smaller. When the pile spacing is set to 2 d^4 d, the pile length is set to 24 m^32 m, and the pile stiffness is set to 0.5EI^1.0EI, the double-row pile retaining structure has the highest cost performance.