Influence of Open Dewatering on the Deformation of Deep Foundation Pit in Saturated Soft Loess Area
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摘要: 饱和软黄土是一种有别于湿陷性黄土、饱和压密黄土的特殊地层。为分析敞开式降水对富含饱和软黄土地层深基坑变形影响,选取西安地区某典型深基坑为剖析对象,分析降水前、后土层物理力学性能变化,探讨降水前、后饱和软黄土地层的粘结强度,对比研究降水前、后对深基坑变形的实测值与计算值。研究成果可在物理力学性能变化、粘结强度提升和变形控制方面为富含饱和软黄土地层深基坑设计参数选取时提供参考,为类似项目积累地区经验。Abstract: Saturated soft loess is a special stratum different from collapsible loess and saturated compacted loess. In order to analyze the influence of open dewatering on the deformation of deep foundation pits in strata rich in saturated soft loess, a typical deep foundation pit in Xi'an was selected for analysis. The changes of soil physical and mechanical properties before and after dewatering were analyzed in detail, the bond strength of saturated soft loess strata before and after dewatering was discussed, and the measured and calculated values of deformation of deep foundation pits before and after dewatering were compared. The research results provide a reference for the selection of design parameters for deep foundation pits in layers rich in saturated soft loess in terms of changes in physical and mechanical properties, bond strength improvement and deformation control, and provide regional experience for similar projects.
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Key words:
- open dewatering /
- deep foundation pits /
- saturated soft loess /
- deformation
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表 1 土的基本物理力学性质指标
层
号层厚
/m土层
类别重度γ
/(kN·m−3)黏聚力c
/kPa内摩擦角φ
/(°)液性指数IL 粘结强度标准值/kPa ① 0.4~1.8 填土 18.5 10 10 25 ② 2.0~8.1 黄土 14.8 20 23 0.14 65 ③ 1.7~4.6 饱和
软黄土18.4 16 18 0.90 40 ④ 2.0~4.3 古土壤 19.9 30 21 0.30 60 ⑤ 8.7~10.3 黄土 19.6 22 21 0.56 50 表 2 降水前、后③层饱和软黄土的物理力学性质指标
阶段 γ/
(kN·m−3)w
/%e Sr
/%IL a1-2
/MPa−1c
/kPaφ/(°) 降水前 18.6 32.9 0.943 95 0.96 0.54 16 19.2 降水后 17.3 23.9 0.969 66.8 0.72 0.41 26 23.8 -
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