@article{oai:niigata-u.repo.nii.ac.jp:00028039, author = {丸井, 英明 and 渡部, 直喜 and 佐藤, 修 and 前川, 峰志}, journal = {新潟大学積雪地域災害研究センター研究年報, 新潟大学積雪地域災害研究センター研究年報}, month = {Mar}, note = {The background and mechanism of the Gamahara Torrent debris flow of 6 December, 1996 is reported. It is very unusual that the debris flow occurred at the beginning of December in terms of the necessary water supply. Clearly the debris flow was triggered by landslide which occurred at the geological formation boundary at an elevation of about 1,300m. The soil layer above the formation boundary probably contained very much water due to antecedent rainfall before the occurrence of the landslide. Chemical analysis of the water contained in the debris flow deposit should provide an effective measure of identifying the origin of this water. Chemical analysis results showed that the water in the debris flow deposit did not originate directly from rainfall and snow melt but came from stored groundwater. This report interprets also the physical and mechanical properties of the unstable debris deposits in the various areas of the Gamahara torrent basin. Various geotechnical investigations were performed in order to analyze the mechanism and the process of the debris flow. The shear strength parameters of debris flow deposits on the torrent floor in the lower part of the watershed and slope failure deposits in the landslide scar which triggered the debris flow were determined by using a ring shear apparatus.}, pages = {23--48}, title = {蒲原沢土石流災害について (大木靖衛教授退官記念号)}, volume = {19}, year = {1998} }