[H-DS09] [EE] Landslides and related phenomena

[HDS09-01] On the fluidized landsliding phenomena on gentle slopes triggered by the 2016 Kumamoto Earthquake

*王 功輝¹、土井 一生¹、釜井 俊孝¹、後藤 聡²、千木良 雅弘¹ (1.京都大学防災研究所、2.山梨大学工学部 大学院 医工農学総合教育部)

キーワード：fluidized landslide, earthquake, tephra

During the 2016 Kumamoto earthquake, numerous landslides had been triggered in Minamiaso Village. Most of the landslides originated on steep slopes, whereas some of them occurring on gentle slopes were fluidized and the displaced debris travelled long travel distance, resulting in causalities and severe damage to many houses on the downslope. In this study, we examined the geological features of these fluidized landslides occurring on gentle slopes, and performed both in-situ direct shear tests and dynamic ring shear tests on the soils taken from the sliding surface. During the tests, the samples were prepared at different initial water contents, and dynamic tests were performed by applying cyclic loadings with regular frequency and amplitude of shear stress, and also by coseismic loading referred from seismic motion recorded in a seismic station nearby. Based on these results, we finally analyzed the possible initiation and movement mechanisms of these fluidized landslides.