著者
加納 誠二 土田 孝 中川 翔太 海堀 正博 中井 真司 来山 尚義
出版者
公益社団法人 地盤工学会
雑誌
地盤工学ジャーナル (ISSN:18806341)
巻号頁・発行日
vol.6, no.2, pp.243-259, 2011-06-30 (Released:2011-07-01)
参考文献数
11
被引用文献数
1 1

2009年7月24日から25日にかけての連続した降雨により,東広島市志和町内うち地区の残土処分場で崩壊が発生し,流動化した土砂が流下して住宅1戸が全壊した。本論文は本災害の原因について考察したものである。災害発生箇所は何回かの地形改変を経て残土処分場となっていたため,三次元レーザー測量による崩壊後の地形の把握,軽量動的コーン貫入試験による崩壊土砂堆積厚さの調査,過去の測量地図,航空写真の解析を行って,地形改変履歴を明らかにし崩壊直前の地形を推定した。崩壊した残土斜面の底部には帯水層が存在し豊富な地下水が流れており,崩壊後の現地調査と降雨後の地下水位の上昇を考慮した安定解析により,地下水位が帯水層から約9m 上昇し斜面全体の安全率が1 以下となり,すべり崩壊が発生したと推定された。降雨によって飽和度が高まっていた崩壊土砂は,地下水の流出とともに流動化し約9°の傾斜を500m 流下したと考えられる。
著者
海堀 正博 長谷川 祐治 山下 祐一 崎田 博史 中井 真司 桑田 志保 平松 晋也 地頭薗 隆 井良沢 道也 清水 収 今泉 文寿 中谷 加奈 柏原 佳明 加藤 誠章 鳥田 英司 平川 泰之 吉永 子規 田中 健路 林 拙郎
出版者
公益社団法人 砂防学会
雑誌
砂防学会誌 (ISSN:02868385)
巻号頁・発行日
vol.71, no.4, pp.49-60, 2018-11-15 (Released:2019-11-15)
参考文献数
10
被引用文献数
8

In July 2018, heavy rain due to Typhoon Prapiroon affected western Japan and caused numerous sediment disasters such as landslides and debris flows in Hiroshima Prefecture. In a southern part of Hiroshima, approx. 8,500 slope failures occurred, and total number of sediment disasters were reported as approx. 1,250. Therefore, members of Japan Society of Erosion Control Engineering and Chuushikoku branch conducted field surveys in Hiroshima City, Aki Gun, Kure City, and Higashi-hirosima City. In Kawasumi area, Aki Gun, large rock which seemed to be core stone and diameter approx. 10 m moved down from the torrent, and at downstream side 6 m diameter rock seemed to hit the house with destructive power. In Aki-Gun, Saka-Cho, Koyaura area, one old stone masonry sabo dam was destroyed. We estimated the flow discharge from the investigation at the upstream of dam and considered the flow process from the flow traces around the dam. The results showed that the dam destroying process was as following. Firstly, the large rocks accumulated at the frontal part of debris flow collided and destroyed the right bank side wing, and then stone masonry product peeled off continuously. Furthermore, debris flows occurred from several streams in Koyaura and 1-1.5 m sediment deposition occurred at downstream residential area. In Higashihiroshima City Kurose-cho, many collapses and debris flows occurred around Hiroshima International University and there were no casualties fortunately. In Kurose-cho, most of the collapses seemed to occur from the top and ridge of the mountains with gentle slope around 15 degrees.
著者
牛山 素行 里深 好文 海堀 正博
出版者
日本自然災害学会
雑誌
自然災害科学 (ISSN:02866021)
巻号頁・発行日
vol.18, no.2, pp.165-175, 1999-08-31
被引用文献数
2

The heavy rainfall disasters occurred mainly in Hiroshima Prefecture on June 29th, 1999. The death toll in the whole country was 41. This damage is the biggest after the typhoon disasters in September 1993. The maximum daily precipitation around Hiroshima City was about 260 mm and the maximum hourly precipitation was about 70 mm. These records became one of the highest records around Hiroshima City. The heavy rainfall area was local; the area with more than 200 mm daily precipitation was about 10 km (east - west), 30 km (north - south). Most of the dead persons were killed by the sediment disasters. There are 5,960 hazardous place for steep slope failure and 4,930 dangerous streams of debris flows in Hiroshima Prefecture, which are the highest in Japan. Based on this event, it is necessary to construct warning and evacuation system, to examine a way of land use and so on in the future.