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张昭, 刘奉银, 张国平. 土在全含水率范围内持水及非饱和渗透特性的模型描述[J]. 岩土工程学报, 2014, 36(11): 2069-2077. DOI: 10.11779/CJGE201411013
引用本文: 张昭, 刘奉银, 张国平. 土在全含水率范围内持水及非饱和渗透特性的模型描述[J]. 岩土工程学报, 2014, 36(11): 2069-2077. DOI: 10.11779/CJGE201411013
ZHANG Zhao, LIU Feng-yin, ZHANG Guo-ping. Models for water retention and unsaturated permeability in full range of water content[J]. Chinese Journal of Geotechnical Engineering, 2014, 36(11): 2069-2077. DOI: 10.11779/CJGE201411013
Citation: ZHANG Zhao, LIU Feng-yin, ZHANG Guo-ping. Models for water retention and unsaturated permeability in full range of water content[J]. Chinese Journal of Geotechnical Engineering, 2014, 36(11): 2069-2077. DOI: 10.11779/CJGE201411013

土在全含水率范围内持水及非饱和渗透特性的模型描述

Models for water retention and unsaturated permeability in full range of water content

  • 摘要: 传统的持水及非饱和渗透系数模型在较高含水率范围预测较好,而在较低含水率范围预测较差。一方面引入分界点将用体积含水率表示的持水曲线分为毛细阶段和吸附阶段,当土比分界点干燥时假定残余体积含水率与基质吸力的关系,改进Van Genuchten模型在较低体积含水率范围的适用性,将其推广至全体积含水率范围。另一方面,引入修正系数改进表征等径球体颗粒集合体内薄膜流动的非饱和渗透系数模型,并将非饱和渗透系数表示为毛细流动和薄膜流动对其贡献之和,以实现其在全体积含水率范围内从毛细流动到薄膜流动的光滑过渡。最后利用已有文献中6种壤土在较高、较低体积含水率范围内的持水以及非饱和渗透试验结果验证了修正持水及非饱和渗透系数模型的准确性,结果表明:这2种修正模型在全体积含水率范围内较传统模型的预测效果更好。

     

    Abstract: The existing models for water retention and unsaturated permeability are successful at higher water contents but often give poor results at lower water contents. The water retention curve can be divided into capillary and adsorption segments by a dividing point, where the residual volumetric water content is assumed to vary with the matric suction, which can improve the applicability of Van Genuchten model to range of lower volumetric water content, and further extend it to the full range of volumetric water content. In addition, a permeability model for film flow in an even spherical particle assembly is modified by introducing a correction factor. The total unsaturated permeability is then considered to be the sum of those due to capillary and film flows. The two modified models are then verified using the test data of water retention and unsaturated permeability at higher and lower volumetric water contents for six loams in the existing literatures. The results show that the two modified models mach the measurements of water retention and unsaturated permeability better than the traditional models in the full range of volumetric water content.

     

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