Abstract
The eruption activities of Unzen Volcano located at Nagasaki Prefecture had produced huge amount of deposits by frequent occurrence of pyroclastic flows. This volcanic deposits remained at the foot of mountain has much risk of a debris flow along the basin. In order to utilize the volcanic deposits as a construction material, the compressive and static shear properties tests with will be effected by submergence, and more the dynamic tri-axial tests and so on were carefully carried out in the laboratory.
As a result of this study, it was concluded that 1) the high bearing capacity is expected because of the high internal friction angle of this volcanic deposits, 2) it is necessary to compact sufficiently because the fall of strength parameter and the increase of compressive strain will occur by a submergence, 3) liquefaction resistance is high value comparing with the Toyoura standard sand. And it is cleared that the volcanic deposits is a useful material as a fill, a subgrade material and a foundation ground.
