Changes in stability conditions of clay slopes due to leaching: a case study

Abstract

Leaching through natural soil deposits manifests in form of modifications in mechanical parameters of the host soil. One of the outcomes of strength reduction in soils due to leaching is slope instability which is exhibited in the form of sliding. In this study, a series of chemical, physical and mechanical tests have been carried out to investigate the effect of leaching on the stability of a clay slope in north of Iran. Results show that leaching removes the soluble salts from the soil, leaving porous and unstable structure. Leaching causes reduction of the mechanical properties of the host soil including deformation and shear strength parameters in drained and undrained conditions. Results of the laboratory tests revealed that leaching has given rise to more than 30% reduction in the plasticity index, 10% decrease in the dry unit weight and 45% decline of the unconfined compressive strength of the host soil. The leaching-induced diminution of the mechanical performance of the host soil is geared to have some slope instability implications by exhibiting a maximum of 50% reduction in the slop stability safety factor.