抄録
A non-welded part of pyroclastic flow, Shirasu in Japanese, is widely distributed on the ground surface in Kagoshima Prefecture. The slopes composed of Shirasu and other volcanic products often fail due to heavy rain in the rainy season. In order to prevent natural disasters due to shallow landslides, six test field points, where past occurrence of landslides due to heavy rainfall was identified, have been determined in the Takakuma experimental forest of Kagoshima University. In this study, site investigation and in situ tests on shallow landslide scars of Shirasu natural slopes are conducted to investigate the stability of the slopes and the effect of revegetation and soil development of forest topsoils from the viewpoint of forest ecology and geotechnical engineering. In the site investigation, the growth condition of forest trees, the measurement of dry density of topsoil and investigation using soil augers are carried out. Furthermore, simple dynamic cone penetration test and the investigation of slope topsoil using a soil strength probe are performed in situ.
