Hydraulic conductivity function of unsaturated soil over a wide suction range

AbstractLimited experimental studies investigate the hydraulic conductivity function (HCF) of unsaturated soil due to labor-tedious, intensive, and time-consuming test work. The available methods mainly provide data in the low suction range (e.g., < 500 kPa). The way of measuring the HCF over a wide suction range is rarely reported. Predicting the HCF using the soil water characteristic curve is most used due to its simplicity. However, the accuracy of these predictions is rarely examined using experimental data over a wide suction range. This study proposes a filter paper-based column method to explore the HCF of unsaturated soil over a wide suction range, which is convenient, money- and time-saving. The accuracy of this method is verified via the data from a commonly used method (outflow method). And the performance of two typical predicting equations is examined. Results show that the newly proposed method can measure the HCF over a wide suction range of 0-106kPa. The consistency in the HCF from the two testing methods proves the efficiency of the proposed method. Meanwhile, the result indicates that the functions show good estimation in the low suction range (e.g., 100 kPa).