Laboratory determination of Soil-Water Characteristic Curves for cracked soil

In general, unsaturated hydraulic conductivities are more difficult to estimate than are saturated, but as the soil transitions from intact to cracked, the difficulty in estimating the hydraulic conductivity and the water storage properties increases. One critical step in determination of unsaturated flow hydraulic properties lies in the evaluation of the Soil-Water Characteristic Curve (SWCC). In this paper, the authors' experience with a series of laboratory studies of direct measurements of cracked soil SWCCs is presented, including challenges associated with very low suction control. An oedometer-type SWCC apparatus, capable of suction and net normal stress control was used in these lab studies. This paper also addresses how the Air Entry Value (AEV) of the cracks can be calculated theoretically based on capillary theory, and the results are compared against AEVs determined from laboratory tests.