Laboratory and Field Leaching Tests on Coastal Salt‐Bearing Soils

Abstract

Laboratory and field leaching tests were carried out on a gypsiferous sandy silt to determine the effect of soluble salt leaching on the geotechnical properties of this soil known locally as Sabkha. Field tests included penetration and plate bearing tests. Laboratory tests included basic properties, permeability, consolidation, and isotropically consolidated triaxial compression tests with pore‐pressure measurements. Leaching in the laboratory was achieved using distilled water and a hydraulic gradient of 10 and lasted for 5 to 7 days. Leaching in the field was achieved using fresh water. Test results indicate that leaching has resulted in increased permeability, void ratio, and compressibility, and a reduction in the pre‐consolidation pressure in the unconfined lab specimens. The triaxial test results show a decrease in the effective stress strength parameters due to leaching. Field leaching has resulted in 50% reduction in the dynamic cone penetration resistance over a depth of 1–1.5 m but resulted in no change at greater depths. It also reduced the bearing capacity of a standard 0.3‐m‐diameter plate by 42%.