Establishing soil-water characteristic curve and determining unsaturated hydraulic conductivity of kaolin by ultracentrifugation and electrical measurements

Abstract

To establish soil-water characteristic curves (SWCCs) of fine-grained soils, researchers have employed geotechnical centrifuges. However, most of these studies were confined to small acceleration levels and as a result the suction, ?, created in the soil mass was extremely low (<100 kPa). Hence, researchers have resorted to ultracentrifuges, which are capable of generating ? ? 300 kPa. However, the volume of the soil mass used in these centrifuges is too small to be representative of field conditions and determination of moisture content of the soil specimen is done by invasive and destructive techniques. Under these circumstances, utility of electrical measurements (i.e., voltage across two points in the soil mass) for determining soil moisture content, which has the distinct advantage of being both nondestructive and noninvasive and facilitates development of the SWCC, seems to be quite promising. Validity of the technique has been demonstrated by comparing the resultant SWCC, for kaolin, vis-�-vis the SWCCs reported in the literature and those obtained from the pedo-transfer function (PTF). Further, unsaturated hydraulic conductivity (ku) of the kaolin was determined by employing various PTFs available in the SoilVision database and using the relationship proposed by Corey in 1977. It has been observed that the ku values obtained from these relationships match extremely well for ? ? 3000 kPa.