Comparison of Field and Laboratory Soil–Water Characteristic Curves

Results of field monitoring of moisture content and matric suction at the crest and berm of a large cut slope in completely decomposed granite in Hong Kong are reported. Field moisture content and matric suction clearly show that the volumetric water content increases as a result of rainfall infiltration and decreases as a result of evaporation. Correspondingly, the matric suction decreases due to rainfall infiltration and increases due to evaporation. Soil–water characteristic curves at different depths at the crest and near the berm of the cut slope are determined from the field data. Unlike soil–water characteristic curves determined in the laboratory by testing small specimens, the field measured soil–water characteristic curves show negligible hysteresis. Engineering implications of the field soil–water characteristic curves are discussed.