造成地地盤の崩壊  [in Japanese] Destruction in Artificial Ground  [in Japanese]

Destruction and deformation in artificial ground mainly occur in its filled parts, especially at the valley-head shaped part in filled valley. In such geomorphic condition it is apt to concentrate rain water, consequently, it has given rise to many of ground destruction. In natural hills, ground destruction is seen mostly at valley head composed of looses and strata as well as the case of fills in artificial ground. Central Tama hills composed of Inagi Sand Bed which is very loose are the most eminent area in such case, where the head erosion in valley has been done by destruction such as fall, slump and slide by rainrall.