Abstract
Slope disaster in urban residential region happened a lot by “The 2011 off the Pacific coast of Tohoku Earthquake”. These slope disasters brought serious damages such as complete to half collapse houses and broken lifelines, mainly caused by movement of reclaimed area by valley fill or widening of embankment. As a purpose of preventing earthquake disaster at reclaimed area that exist a lot in urban regions in Japan, the features of each slope disaster are categorized in five types and that of each damages are put together based on the investigation results gotten from 42 places. These five types are 1) movement of artificial valley fills, 2) movement of widening of embankment, 3) movement of artificial valley fills and widening of embankment, 4) earth flow of embankment and 5) surface slide. The surface slide that was classified as Type 5 was a damage that appeared to be clear in this earthquake ; the slope become unstable by liquefaction of the foot of slope. Each type of damages happens in the embankment area. Effectiveness of landslide prevention works for reinforcement against earthquake that was constructed after “1978 Miyagiken-oki earthquake” was examined. The examination showed that landslide prevention works (pile work and groundwater drainage work), was effective for large deformation of embankment slope. However, since only landslide prevention works could not control deformation around the foundation of house, it appeared that development of prevention works to improve movement resistance around it is necessary here after. In addition, it appeared to be possible to control mass movement by making a part of uniformly weak movement mass stronger, leading its flank resistance to be increased.
