PRELIMINARY STUDY ON LOADING EXPANSION MODEL OF EXPANSIVE SOIL AND APPLICATION
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摘要: 膨胀土是一种具有强胀缩、多裂隙、反复变形的特殊性黏土。膨胀土对外界环境变化非常敏感,由此而产生的变形与稳定问题是膨胀土地区工程建设的主要课题。本文归纳分析了现有的膨胀模型,基于膨胀土的膨胀变形随初始干密度的增大而增大,随初始含水率与垂向压力的增大而减小的规律性,提出了多因素耦合的膨胀土有荷膨胀模型。在该模型中,用压实度来反映初始干密度的影响,在单因素作为变量时,膨胀率与压实度呈线性关系,与初始含水率、垂向压力成对数关系。对邯郸强膨胀土、南阳中膨胀土与宁淮弱膨胀土的有荷膨胀试验结果进行验证,整体拟合效果较好。进而探讨了膨胀土有荷膨胀模型的工程应用,包括膨胀土地区处理层厚度的估算与膨胀土边坡的衬砌厚度的设计计算。Abstract: Expansive soil is a special clay with remarkable shrink-swell,many cracks,and repeated deformation. It is very sensitive to the change of the external environment,which causes deformation and stability to gradually become the main subject of engineering construction in expansive soil area. This paper summarizes and analyzes the existing expansion models. It is based on the regularity that the swelling deformation of expansive soil increases with the increase of initial dry density and decreases with the increase of initial water content and vertical pressure. It proposes a loading expansion model under multi-factor coupling. In this model,the influence of initial dry density is reflected by degree of compaction. When controlled as a single factor variable,there is a linear relationship between the swelling rate and the degree of compaction,and a logarithmic relationship with the initial moisture content and vertical pressure. The loading expansion test results of strong expansive soil in Handan,medium expansive soil in Nanyang and weak expansive soil in Ninghuai are verified. All the fitting results are better. The engineering application of the model is discussed,including the estimation of the treatment thickness in expansive soil area,and the design and calculation of the lining thickness of the expansive soil slope.
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Key words:
- Expansive soil /
- Swelling deformation /
- Loading expansion model /
- Treatment thickness /
- Lining thickness
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表 1 邯郸强膨胀土基本性质(黄斌等,2011)
Table 1. Basic properties of Handan strong expansive soil (Huang et al.,2011)
液限/% 塑限/% 塑性指数 自由膨胀率/% 最大干密度/g·cm-3 最优含水率/% 62.4 26.2 36.2 124 1.40 30.3 表 2 南阳中膨胀土基本性质(王顺等,2011)
Table 2. Basic properties of Nanyang medium expansive soil (Wang et al.,2011)
液限/% 塑限/% 塑性指数 自由膨胀率/% 最大干密度/g·cm-3 最优含水率/% 64.4 26.1 38.3 79 1.63 24.4 表 3 宁淮弱膨胀土基本性质(张福海等,2010)
Table 3. Basic properties of Ninghuai weak expansive soil (Zhang et al.,2010)
液限/% 塑限/% 塑性指数 自由膨胀率/% 最大干密度/g·cm-3 最优含水率/% 48.0 22.0 26.0 49 1.897 14.2 -
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