Constructing Fast, Accurate Soil Water Characteristic Curves by Combining the Wind/Schindler and Vapor Pressure Techniques

Abstract

The measurement of suction in unsaturated soils is essential in many areas of geotechnical engineering like modeling hydraulic properties or analyzing shrink-swell characteristics from the soil water characteristic curve (SWCC). For many years, filter paper and axis translation made the majority of the SWCCs, but these techniques are time consuming and inaccurate. The vapor pressure method (VPM) overcomes these, but past instruments lacked the resolution in the critical 100 to 1000 kPa range. Recently, technological advances have made it possible to measure soil suction up to 50 kPa. In addition, a new, automated method (Wind/Schindler; WSM) provides the wet end of the SWCC. Several water retention curves were run for a variety of soil types. Characteristic curves crossed over each other smoothly. The VPM method combined with the WSM provide both speed and accuracy to the measurement of soil suction, construction of SWCC, and soil hydraulic properties evaluation.