IMHE OpenIR  > 成都山地所知识仓储(2009年以前)
云南蒋家沟滑坡转化为泥石流观测实验研究
Alternative TitleStudy on Process and Mechanism of Landslides translating to Debris Flows inJiangjia Ravine, Yunnan Province
Language中文
冯自立
Thesis Advisor崔鹏
2005
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Name博士
Degree Discipline自然地理学
Keyword蒋家沟 滑坡 泥石流 砾石土 孔隙率 孔隙水压力 转化机理
Abstract

滑坡转化为泥石流是泥石流形成机理研究中的前沿性基础理论问题,对于泥石流预测预报具有重要意义。本文以蒋家沟流域为典型研究区,通过人工模拟降雨实验以及在泥石流形成源区的实际观测,系统分析了暴雨条件下土体特性以及沟道径流对蒋家沟滑坡转化为泥石流过程的影响,初步揭示了蒋家沟滑坡转化为泥石流的规律。.蒋家沟的滑坡崩塌体多发育于砾石土层中。砾石土的孔隙率对坡体的破坏以及滑坡转化为泥石流的过程具有重要的制约作用:1.砾石土的粘聚力和内摩擦角都随着孔隙率的增加而降低。2.砾石土的饱和导水率和稳定入渗率随着孔隙率的增加而增加。3.孔隙率较小的砾石土坡体,如古老泥石流堆积物形成的上游支沟沟坡和近期泥石流堆积物,在暴雨条件下,含水量水平较低,孔隙水压发展缓慢,数值低,往往发生少量的前缘滑塌,通常不直接转化为泥石流;而孔隙率较高的砾石土坡体在持续暴雨入渗下,含水量水平较高,其浅层土体的孔隙水压急剧上升,导致土体液化直接形成泥石流。沟道径流对滑坡转化为泥石流具有重要作用,在蒋家沟上游源区,短历时暴雨形成的沟道径流冲刷掏蚀坡脚和沟床,使沟岸的坡体发生滑塌,形成松散堆积物,补给泥石流并为泥石流的频繁暴发提供了固体物质基础。

Other Abstract

Landslide translating to debris flows is the frontier problem in the study of mechanism of debris flow formation, it has theatrical and practical significance, it is important for debris flow forecasting. In this dissertation, the study area is Jiangjia Ravine, through simulation rainfall experiments on the landslides in Jiangjia Ravine and durative observation in the upstream area, the influence of rainstorm infiltration and the characteristic of the gravel soil in the Jiangjia Ravine on the process of landslides translating to debris flows is analyzed, and the mechanism of landslides translating to debris flows in Jiangjia Ravine is revealed. Most of the landslides in Jiangjia Ravine are composed of gravel soil, the porosity of the gravel soil influence the failure and translating process of landslides fundamentally: 1. The strength indexes of gravel soil vary at different porosity. With the increase of gravel soil porosity, the cohesion and internal friction angle decrease. 2. The saturated hydraulic conductivity and the stable infiltration rate decrease with the increase of gravel soil porosity. 3. For landslides composed of dense gravel soil, such as the bank slopes formed of archaic debris flow deposits or late debris flow deposits, the pore water pressure -develops slowly, and the value is low during infiltration process, also the water content is not high of the landslides, so often the forepart of the landslides collapses a bit, and it is difficult to translate to debris flow directly. The landslides composed of loose gravel soil behave different from that composed of dense soil, under the condition of durative rainstorm, the pore water pressure of the soil in shallow layer of landslides rise sharply after some time, and the gravel soil liquefied and translating to debris flows directly. In the upstream area of Jiangjia Ravine, short duration rainstorm can form floods and debris flows in branch gullies; the floods and debris flows scour and undermine the foot of landslides beside branch gullies, down cut the gully bed, and result in many collapses of bank slopes, this can replenish debris flows in the gully, it can also form loose solid material in the gully, considering the difference of strength indexes between loose gravel soil and dense gravel soil, this is very important for the frequent eruption of debris flows in Jiangjia Ravine.

Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/6207
Collection成都山地所知识仓储(2009年以前)
Recommended Citation
GB/T 7714
冯自立. 云南蒋家沟滑坡转化为泥石流观测实验研究[D]. 北京. 中国科学院研究生院,2005.
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