In-situ permeability of the unsaturated zone of Nicosia Marl from field wetting experiments

Abstract

The construction of infrastructure in areas with problematic ground conditions, such as the expansive soil of Nicosia marl in Cyprus, points to large economic losses. This research investigates hydraulic and water retention properties of Nicosia marl, namely the in-situ permeability and the hysteretic soil-water characteristic curve, in an effort to understand the potential of infiltration and migration of rainwater inside the unsaturated zone of the soil profile. To achieve this, first the Nicosia marl was examined by laboratory testing after field sampling from three different sites at the University of Cyprus campuses for the determination of the soil-water characteristic curve using a chilled mirror hygrometer. Then, the data acquired by installed field volumetric water content and matric suction monitoring sensors were used in FE simulations for the back calculation of the in-situ permeability in both vertical and horizontal direction. The results indicate that the in-situ permeability is 3 to 4 orders of magnitude larger than the one measured in the laboratory on intact samples. This is attributed to the presence of the shrinkage cracks and the inherent structural fissures of the material.