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    Volume 40, Issue 6 (November 2017)

    A Method for Directly Measuring the Hydraulic Conductivity of Unsaturated Soil

    (Received 18 August 2016; accepted 17 February 2017)

    Published Online: 2017

    CODEN: GTJODJ

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    Abstract

    Numerous methods, such as the Gardner outflow analysis method and the van Genuchten-Mualem prediction model, have been developed to estimate the hydraulic conductivity of unsaturated soil in multistep outflow experiments. In the Gardner outflow analysis method, the hydraulic conductivity is estimated based on the diffusivity calculated from the line fitted to the water outflow. In contrast, in the van Genuchten-Mualem prediction model, it is predicted via the curve-fitting parameters based on the measured soil water retention curve (SWRC). However, a major drawback of these two approaches is that variation of hydraulic conductivity during each step of the outflow process cannot be represented. In this paper, an improved pressure plate instrument with an evaporation compensation system is developed to measure the transient water content curve (TWCC) of the soil in multi-step outflow experiments. The SWRCs of silicon micro-powder (SMP) and Guangxi Guiping clay (GGC) are derived from this transient curve. Therefore, a direct measurement method is presented to describe the change of hydraulic conductivity during each step. Comparison with the Gardner outflow analysis method and the van Genuchten-Mualem prediction model indicates that our approach shows better agreement with test data for these two types of soils.

    Author Information:

    Shao, Longtan

    Wen, Tiande

    Guo, Xiaoxia

    Sun, Xiang


    Stock #: GTJ20160197

    ISSN:0149-6115

    DOI: 10.1520/GTJ20160197

    Author
    Title A Method for Directly Measuring the Hydraulic Conductivity of Unsaturated Soil
    Symposium ,
    Committee D18