王政1,2,
田树峰1,2,
朱云华3
1. 中国科学院、水利部成都山地灾害与环境研究所, 中国科学院山地灾害与地表过程重点实验室, 四川 成都 610041
2. 中国科学院大学, 北京 100049
3. 西南石油大学地球科学与技术学院, 四川 成都 610050
基金项目: 国家自然科学基金项目（批准号：41671112）、国家自然科学基金国际（地区）合作与交流项目（批准号：41861134008）和四川科技计划项目重点研发计划项目（批准号：18ZDYF0329）共同资助
详细信息
作者简介: 陈宁生, 男, 54岁, 研究员, 从事山地灾害形成机理及其防治技术研究, E-mail:chennsh@imde.ac.cn
中图分类号: P642.3 收稿日期:2019-04-25
修回日期:2019-06-27
刊出日期:2019-09-30
Study on debris flow process induced by moraine soil mass failure
Chen Ningsheng1,,Wang Zheng1,2,
Tian Shufeng1,2,
Zhu Yunhua3
1. Key Laboratory of Mountain Hazards and Surface Process, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, Sichuan
2. University of the Chinese Academy of Sciences, Beijing 100049
3. School of Geoscience and Technology, Southwest Petroleum University, Chengdu 610050, Sichuan
MSC: P642.3
--> Received Date: 25 April 2019
Revised Date: 27 June 2019
Publish Date: 30 September 2019
摘要
摘要:与广泛分布于干旱河谷的宽级配砾石土体特征不同，冰碛土广泛分布在青藏高原地区，属粗大颗粒多、粘粒含量少、摩擦阻力大、粘滞阻力小的宽级配砾石土体。在冰川融雪与降雨的共同作用下冰碛土体可失稳并起动泥石流，形成灾害。针对冰碛土体起动泥石流机理研究薄弱的现状，本文选取波密县帕隆藏布流域的支流嘎弄沟一冰碛土堆积坡面，通过模拟降水与冰雪融水起动冰川泥石流实验，比较不同颗粒组成、不同实验条件下的土体起动泥石流特征，分析其起动成因及力学特性，探讨冰碛土体起动泥石流的机理。研究发现冰碛土体失稳起动泥石流是粘滞阻力降低、孔隙水压力升高、拖曳力与渗流侵蚀共同作用的结果，起动过程受粘土颗粒含量和径流类型的影响。当粘粒含量较高时（> 3%），土体通过铲蚀与面蚀形成泥石流；粘粒含量中低时（不高于3%），大部分坡面土体主要经掏蚀与坍塌起动泥石流；粘粒含量过低时（< 0.32%），土体难以起动泥石流。在降水作用下土体孔隙水压力迅速增加，易造成土体破坏，起动泥石流；而在冰雪融水的作用下，土体孔隙水压力波动幅度不大时，土体同样可能发生失稳破坏起动泥石流。
关键词: 冰碛土体/
帕隆藏布流域/
冰雪融水试验/
力学特性/
起动机理
Abstract:The triggering mechanisms of debris flow were explored in the field by means of artificial rainfall and glacial melt water experiment in the Ganonggou (29°57'57"N, 95°43'27"E), Parlung Zangbo basin and Tibet, China. The spatial distribution of the moraine in this area is:the low clay content moraine soil is at the top, the medium clay content weathered moraine soil is in the middle, and the medium-low clay content moraine soil formed by landslides and debris flow transformation is at the bottom. The results of the soil of fractal calculation, direct shear test and large-scale triaxial test shows:The grain size distribution of moraine is good. When the grain-size fractal dimension is within the range of 2.396~2.658, the cohesive force increases with the value of grain-size fractal dimension, while the angle of internal friction decreases with it.
We found that the clay content is a critical factor affecting the triggers of debris flow in moraine by analyzing the artificial rainfall and the glacial melt water experiment. When the clay content is higher than 3%, the major triggers of debris flow in moraine combine with scouring erosion and surface erosion; when the clay content is not higher than 3%, the debris flow in moraine is mainly triggered by undercutting erosion and collapse; when the clay content is lower than 0.32%, it is difficult for moraine to trigger the debris flow. The triggers of debris flow in moraine can be divided into two categories:One is gravity viscous trigger, whose instability is mainly affected by the reduction of moraine viscosity resistance. In this experiment, the influence of the decrease of the viscosity resistance is 45%; The other is hydraulic trigger, which is mainly affected by the hydraulic slope. When the hydraulic slope exceeds the critical value, the soil will undergo liquid flow. In this experiment, the critical slope triggering debris flow in moraine is 0.89.
Key words:moraine soil/
Parlung Zangbo basin/
glacial meltwater test/
mechanical properties/
triggering mechanism
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