Measurement of Hydraulic Conductivity of Partially Saturated Soils

by ]. M. Hamilton, Geotechnical Engineer; Law Engineering Testing Co., Houston, TX 77024,
D. E. Daniel, Assistant Professor; University of Texas at Austin, Department of Civil Engineering, Austin, TX 78712,
R. E. Olson, Professor of Civil Engineering; University of Texas at Austin, Department of Civil Engineering, Austin, TX 78712,

Part of: From Soil Behavior Fundamentals to Innovations in Geotechnical Engineering: Honoring Roy E. Olson


Increased interest in protection of the environment has led to a need to be able to predict long-term movement of moisture, and contaminants, in the vicinity of shallow land disposal sites for various toxic and radioactive wastes. The advantages of locating potential sites in arid regions has led to a need to develop means for predicting moisture movements in fairly dry, partially saturated soils and for measurements of the hydraulic conductivities of such soils. A technique was developed in which thermocouple psychrometers and the instantaneous profile method were used to measure conductivities of soils with suctions as high as 80 atm. For one clay of low plasticity, the conductivity dropped from about 10-7 cm/s when saturated to almost 10-12 cm/s for degrees of saturation of the order of 30 percent. Measured conductivities were used in a finite element solution to Darcy's equation to predict final water content profiles. The predicted and measured profiles compared well, which suggests that the measured conductivities were tolerably accurate. Based on data presented, the proposed technique seems promising for conductivity measurements in clays with degrees of saturation between about 30 and 90 percent and in sands with 5 to 50 percent saturation.

Copyright holder: Previously published in Permeability and Groundwater Contaminant Transport, ASTM STP 746, 1981, 182-196


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