Volume 34, Issue 6 (November 2011)

    Towards a Tensiometer Based Suction Control System for Laboratory Testing of Unsaturated Soils

    (Received 6 January 2011; accepted 3 June 2011)

    Published Online: 2011

    CODEN: GTJOAD

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    Abstract

    This paper presents the development of an automated tensiometer based suction control system for testing unsaturated soil samples. The system is able to dry and wet soil, while measuring suction (pore water pressure – air pressure) and water content. The system uses air circulation within a closed loop to dry the soil, or water injection to wet the soil, to achieve the required pore water pressure while the air pressure is kept atmospheric. Pore water pressure is controlled by using a feedback computer system that dries or wets soil samples according to measurements obtained from sample-mounted high suction tensiometers. Excess moisture in the air circulation loop is captured by an in-line moisture trap consisting of a sealed cell containing a desiccant (silica gel), which is placed on an electronic balance to give continuous measurements of retained water. Changes of the sample water content are measured as the difference between the amount of water injected and that retained by the moisture trap. The system is fully automated and runs controlled by software with minimum assistance. The proposed suction control system presents advantages over the conventional axis translation technique as it avoids the need for elevated pore air pressures and hence better replicates the natural processes of wetting and drying of soils. The system was developed for use in a triaxial cell, but could also be used with other instruments and for the determination of water retention curves.


    Author Information:

    Lourenço, Sérgio D. N.
    Cardiff Univ.,

    Gallipoli, Domenico
    Univ. of Glasgow,

    Toll, David G.
    Durham Univ.,

    Augarde, Charles E.
    Durham Univ.,

    Evans, Fred D.


    Stock #: GTJ103755

    ISSN: 0149-6115

    DOI: 10.1520/GTJ103755

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    Author
    Title Towards a Tensiometer Based Suction Control System for Laboratory Testing of Unsaturated Soils
    Symposium , 0000-00-00
    Committee D18