Abstract
This paper attempts (1) to explain the angle of natural slope frequently affected by shallow slab slide by means of stability analysis, and (2) to investigate the influence of parameters related to the stability analysis on the frequency distribution of slope angles. Two areas, Mineoka and Hota areas, underlain by tertiary sedimentary rocks are chosen for the investigation. The frequency distribution of slope angles show a range from 7.8° to 15.7° and a mode at 12° in the Mineoka area, and from 11.4° to 20.2° and at 14° in the Hota area. Infinite Slope analyses for six slopes indicate that the actual slope angles agree with the critical stability angles calculated under (1) residual strength and (2) highest value of water table. Strength parameters, Cr′ and φr′, and the depth of slip surface are mare important than other parameters when considering the scattering of the frequency distribution of each of the areas. Strength parameters are most important when considering the difference of the modes between two areas.
