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工程科学与技术:2020,52(6):30-39
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西藏瓦来高速远程滑坡的运动学过程与碎裂化特征
(1.中国地质大学(北京) 工程技术学院,北京 100083;2.四川大学 水利水电学院,四川 成都 610065)
Kinematic Processes and Fragmentation Characteristics of Walai Rock Avalanche Landslide in Tibet
(1.School of Eng. and Technol., China Univ. of Geosciences, Beijing 100083, China;2.College of Water Resource & Hydropower, Sichuan Univ., Chengdu 610065, China)
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投稿时间:2020-03-30    修订日期:2020-10-12
中文摘要: 岩石的碎裂化作为高速远程滑坡中的一种重要现象,其不仅是颗粒流假说的基础,也涉及到滑坡能量的耗散与传递作用。以西藏八宿县瓦来滑坡为例,通过遥感影像解译、野外调查和粒度试验等方法,对山谷型高速远程滑坡的地貌特征、堆积结构、运动学过程及碎裂化特征进行分析和探讨。基于无人机航测数据构建的高精度数字高程模型,对瓦来滑坡的地貌结构进行定量化分析。依据等高线特征与基岩分布特征重建滑坡前地形,并对瓦来滑坡的体积进行估算。结果表明:瓦来滑坡是一个受层面和两组节理控制的碎屑流型高速远程滑坡,其水平运动距离为3 480 m(H/L=0.32),堆积方量约为5.1×107 m3。瓦来滑坡的主要地貌结构为修剪线、巨型丘、纵向脊和压缩脊,这些地貌结构指示了滑坡启动后朝NE48°方向运动,遇到山体阻挡后偏转向北。瓦来滑坡的外壳相较薄,明显受到岩层节理控制;滑体相中的堆积结构以分层结构、拼图结构、块石定向排列、块石剪切破坏为主,这些结构指示瓦来滑坡具有层流运动特征,且其运动过程中,内部存在碰撞作用与剪切作用。滑体相中,粒度沿程的变化特征表明瓦来滑坡的内部破碎主要发生在从滑坡源区经过流通区到坡脚的撞击过程中,为强破碎阶段;细颗粒的粒度分布特征和发育不明显的细粒剪切带指示该滑坡在径向运动阶段的破碎作用相对前者较弱,为弱破碎阶段。
Abstract:Fragmentation is a very common phenomenon in high-speed long runout landslides, which is not only the basis of the granular flow hypothesis, but also related to energy dissipation and transmission of landslide. In order to examine the kinematic and fragmentation characteristics of long runout landslides, the Walai rock avalanche landslide was studied as an example. According to the remote sensing interpretation, field investigation and grain size tests, the geomorphologic features, sedimentary structures, kinematic processes and fragmentation characteristics of Walai rock avalanche landslide were analyzed and discussed. The geomorphic structures were quantitatively analyzed based on the high precision digital elevation model built by unmanned aerial vehicle measurement. The contour map and bedrock data were used to reconstruct the pre-topography and the volume of this rock avalanche was estimated. The results indicated that the Walai rock avalanche landslide was controlled by the rock joints, its horizontal travel distance reached 3480 m (H/L = 0.32) and the accumulated volume was about 5.1×107 m3. The geomorphic structures of the Walai rock avalanche landslide was characterized by trimlines, huge hummocks, longitudinal ridges and compressed ridges. These geomorphologic structures indicated that the Walai rock avalanche landslide moved in the northeast direction at first, and turned to the north when it encountered the eastern mountain. The carapace facies of Walai rock avalanche landslide was thin, and the blocks was approximately 30 cm, which was significantly influenced by the joints. The sedimentary featured in body facies, including the stratified layers, jigsaw structures, directional arrangements and shear failure of block, indicating that the rock avalanche moved as a laminar flow and there were collision and shear actions during the movement. The change in the size of blocks in body facies suggested that the fragmentation mainly formed due to the impact actions from the source area to the toe of the transition zone; and the fine grain distribution characteristics and absence of obvious shear zone indicated that the internal shear behavior during the radial motion stage was not stronger than that of the former.
文章编号:202000237     中图分类号:P694    文献标志码:
基金项目:国家重点研发计划项目(2018YFC1505003)
作者简介:陈剑(1975-),男,副教授.研究方向:地质灾害与工程地质.E-mail:jianchen@cugb.edu.cn
引用文本:
陈剑,陈瑞琛,米东东,郑欣欣,高春玉.西藏瓦来高速远程滑坡的运动学过程与碎裂化特征[J].工程科学与技术,2020,52(6):30-39.
CHEN Jian,CHEN Ruichen,MI Dongdong,ZHENG Xinxin,GAO Chunyu.Kinematic Processes and Fragmentation Characteristics of Walai Rock Avalanche Landslide in Tibet[J].Advanced Engineering Sciences,2020,52(6):30-39.