ABSTRACT
Various studies on landslides have long been carried out at different sites along fractured zones of Median Tectonic Line in Shikoku, Japan. The study carried out in this paper relates to the landslide sites where the soil of the slip layer is hydrothermal metamorphic clay that is a clay formed by the hydrothermal alteration of metamorphic rocks. Soil samples from three such landslide sites were collected and tested for strength and clay minerals content. Tri-axial compression and ring shear test results showed that (ϕ)’ and ϕ r of hydrothermal metamorphic clay range from 19° to 45° and 7° to 37° respectively. It was also clear that ϕ r for hydrothermal metamorphic clay is very low; and the difference in ϕ′ and ϕ r is higher compared to that for other clays. Results of x-ray diffraction showed mica and chlorite content in most of the soil samples. However, samples with lesser ϕ r values were found to contain smectites and expansive chlorites.
