Geomorphological processes due to intermittent sediment movements such as land slides and slope failures

间歇性沉积物运动（例如滑坡和斜坡崩塌）造成的地貌过程

• 批准号: 17360229
• 负责人: IZUMI Norihiro
• 金额: $ 3.48万
• 依托单位: Hokkaido University (2006-2007)Tohoku University (2005)
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2005
• 资助国家: 日本
• 起止时间: 2005 至 2007
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17360229/
• 关键词: surface sheet flow; gully; channel bifurcation; seepage flow; slope failure; landslide; sediment hazard probability; snowmelt; 水路網; 分岐; 液状化; 不飽和土; 不飽和地盤; 動的解析; 有限要素法; 土砂災害; リスク; 水路群; 線形安定性理論; 地下水; パイピング; 斜面災害; 極値降雨

A mathematical model is proposed to describe the channelization on slopes composed of weakly cohesive fine sediment. The analysis is extended to include the case of slopes with arbitrary shapes. The spacing of incipient channels is found to be on the order of 1000 times the Froude critical depth of surface sheet flow. A mathematical model of channel bifurcation is also proposed. The analysis reveals that channel heads become unstable and channel bifurcation takes place when the discharge decreases. The results are found to be consistent with observations. The formation of channels due to seepage erosion is studied experimentally. It is found that governing parameters are discharge, slope and seepage layer thickness and that the spacing increases with those parameters.A liquefaction analysis for capillary zone above ground water level is developed based on porous media theory with three phases. Simplified governing equations are derived with the assumption that the relative acceleration of pore fluid with respect to soil skeleton is small. The proposed method can reproduce the tri-axial test results well when the degree of saturation is larger than about 70%. The numerical results show that liquefaction occurred in the capillary zone when the initial saturation degree is about 60% and over.Hydraulic gradient was analyzed by infiltration analysis with consideration of snowmelt. The probability and the road damage in the Tohoku region are shown in maps with 1 km resolutions. These maps show spatial-temporal risk distributions of sediment hazard due to some snowmelt conditions. We also focus on the influence of dam reservoirs to cause excessive sediment disasters due to anomalous weather conditions by global warming. Results of this study conform that the sediment hazard probability model performs well to predict macro scale sediment storage in dam reservoirs.

提出了一个描述细颗粒泥沙坡面渠化的数学模型。分析扩展到包括任意形状的斜坡的情况下。初始通道的间距被发现是在1000倍的弗劳德临界深度的表面片流的顺序。提出了河道分岔的数学模型。分析表明，当流量减小时，渠首失稳，出现了分岔现象。结果与观测结果一致。对渗透侵蚀形成渠道的机理进行了实验研究。研究发现，流量、坡度和渗透层厚度是影响液化的主要参数，且渗透层间距随流量、坡度和渗透层厚度的增大而增大;基于三相多孔介质理论，建立了地下水位以上毛管带液化分析方法。假设孔隙流体相对于土骨架的相对加速度较小，推导出简化的控制方程。当饱和度大于70%时，该方法能较好地再现三轴试验结果。结果表明，当初始饱和度大于60%时，液化发生在毛管区。东北地区的概率和道路损坏情况显示在分辨率为1公里的地图上。这些地图显示了由于某些融雪条件造成的泥沙灾害的时空风险分布。我们还重点研究了全球变暖引起的异常气候条件对大坝水库造成泥沙灾害的影响。研究结果表明，泥沙灾害概率模型能较好地预测水库泥沙淤积量。

项目成果

斜面上に形成される水路の分岐過程について

关于斜坡上形成的水道的分支过程

• 发表时间: 2007
• 期刊: 平成18年度土木学会東北支部技術研究発表会講演概要集
• 作者: H. Mizushima;N. Izumi and G. Parker;水嶋大樹
• 通讯作者: 水嶋大樹

ガリの発達とそれに伴う土砂生産過程

沟渠及相关沉积物生产过程的开发

• 发表时间: 2006
• 期刊: 水工学論文集 Vol.50
• 作者: H. Mizushima;N. Izumi and G. Parker;水嶋大樹;川越清樹;川越清樹;水嶋大樹
• 通讯作者: 水嶋大樹

任意形状を有する斜面上における水路形成の線形安定論

任意形状边坡河道形成的线性稳定性理论

• 发表时间: 2006
• 期刊: 土木学会論文集 No.810/II-74
• 作者: H. Mizushima;N. Izumi and G. Parker;水嶋大樹;川越清樹;川越清樹;水嶋大樹;泉 典洋
• 通讯作者: 泉 典洋

Fundamental study on water quality of reservoirs and slope failures in basins

水库水质与流域边坡破坏基础研究

• 发表时间: 2007
• 作者: Akimoto;T.;Kawagoe;S.;Kazama;S. and Sawamoto;M.
• 通讯作者: M.

Risk evaluation of sediment hazard due to snowmelt in Japan

日本融雪泥沙灾害风险评估

• 发表时间: 2008
• 期刊: Annual J. of Hydraulic Engineering Vol. 52
• 作者: Kawagoe;S.;Kazama;S. and Sawamoto;M.
• 通讯作者: M.