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Apparatus for the rapid automated measurement of unsaturated soil transport properties
Author(s) -
Salehzadeh A.,
Demond A. H.
Publication year - 1994
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/94wr01495
Subject(s) - capillary action , capillary pressure , hydraulic conductivity , imbibition , relative permeability , saturation (graph theory) , soil water , porous medium , materials science , geotechnical engineering , permeability (electromagnetism) , porosity , environmental science , soil science , composite material , chemistry , geology , membrane , biochemistry , germination , botany , mathematics , combinatorics , biology
To describe the flow of water in unsaturated soils, the constitutive relationships of capillary pressure and relative permeability are necessary. To measure these relationships using traditional methods may require different experimental apparatuses and can be time‐consuming, particularly for multiple drainage and imbibition relationships for systems containing surfactants at various concentrations. Thus a critical need exists for an apparatus that can make rapid measurements. This paper outlines the design of an automated apparatus that can produce both capillary pressure and relative permeability relationships simultaneously and rapidly. The rapidity of the measurements is based on the use of a thin soil sample, a highly conductive capillary barrier, and stripper tensiometers. The capillary pressure is changed externally, with the change within the sample monitored through the use of tensiometers. Saturation is determined by monitoring the cumulative effluent, with the accuracy of the mass balance enhanced through the active removal of air bubbles from beneath the capillary barrier. A comparison of capillary pressure relationships for a fine‐grained sandy porous medium produced with this apparatus with those produced with a Tempe cell shows that this apparatus yields comparable measurements in about 2% of the time. Thus the burden of making multiple transport property measurements can be reduced considerably through the use of this apparatus.