Abstract
The case record is reported, each in which the landslide took place along the fissured zone of Osaka soft rock group in the residential land development area at Sakai city of Osaka. A series of investigation including in-situ and laboratory direct shear tests, the analysis of diatom content etc. was carried out in order to examine the failure mechanism by considering the geological background. It was manifested that i) the basic properties were significantly different between the marine clay and the fresh-water formed clay, ii) the shear strength of marine clay was smaller than that of the fresh-water formed clay, iii) the fissured zone in the marine clay is likely to be formed, and iv) the shear strength of the fissured clay subjected to cyclic shear in direct shear box test was close to the back-analyzed shear strength of the slope.
