Characteristics of unsaturated compacted clay

Abstract

Compacted clays are very important in the field of geotechnical engineering, as they are often utilized in landfills and other waste containment facilities as liners or caps, which can act as effective barriers against the flow of water and contaminants. These compacted soil barriers are often unsaturated and few studies have investigated or modelled the unsaturated hydraulic properties which would govern flow through these clays. When dealing with compacted clays there are several parameters which control their unsaturated hydraulic properties. Some of these parameters are fairly simple to quantify in a laboratory, while others are quite labour intensive. One necessary property is the soil-water characteristic curve (SWCC). Most SWCC values described in the literature are for sandy or loamy soils; there has been little research done on clays. Therefore, establishing an empirical relationship using easily quantifiable parameters (i.e., optimum moisture content and plasticity index) to determine the fitting parameters used in the equations used to describe the shape of these curves for clays would be useful as it could potentially eliminate extensive laboratory testing. This report documents the attempt to test these empirical relationships found in the literature through performing a series of tests on a number of compacted clay samples while varying some of the hydraulic parameters; primarily water content. Results from this experiment were found to deviate significantly from the published values.