叠覆堆积过程中泥石流偏移的实验研究
Experiments on Debris Flow Migration in the Process of Overlapping Deposition
李琪敏 1刘晶晶 1汪洋 2刘兆旭 3龚旭1
作者信息
- 1. 中国科学院、水利部成都山地灾害与环境研究所山地自然灾害与工程安全全国重点实验室,成都 610299;中国科学院大学,北京 100049
- 2. 中国科学院、水利部成都山地灾害与环境研究所山地自然灾害与工程安全全国重点实验室,成都 610299
- 3. 西藏大学工学院,拉萨 850000
- 折叠
摘要
泥石流堆积扇经过多期叠覆堆积,其在空间和时间分布上有随机性,存在主流偏移和堆积摆动等各向异性现象,给合理规划与利用泥石流滩地带来困难.本文在野外调查四川平武县碓窝梁子沟堆积扇的基础上,开展室内水槽模型实验,结合3D扫描技术和基底压力传感器,探讨泥石流在叠覆堆积过程中的阶段性流态变化以及主流偏移的成因和发展.实验发现:(1)泥石流密度差异导致不同的偏移形式,高密度泥石流易出现层面整体偏移;低密度泥石流易形成插入式的叠覆堆积.(2)泥石流多期堆叠过程中偏移行为并不一定是沿地势更低处,而是取决于后期来流的性态.(3)泥石流偏移角度和距离依赖于流体密度、流速和堆积体几何特征,可以建立以上述参数为变量的堆积偏移角度与偏移距离的计算公式.本研究成果可以为了解泥石流堆积扇的形成机制、致灾范围和演化趋势提供依据.
Abstract
A debris flow fan is a typical debris flow sedimentary facies,which generally suffered from overlapping and accumulating by multiple debris flow torrents,and has randomness in spatial and temporal distribution,with anisotropic features such as mainstream migration and oscillating sedimentation,all of which brings difficulties in rational planning and utilization of piedmont beach-land created by debris flow sedimentation.In this paper,a debris flow fan located at the Duiwoliangzi gully,Lianghebao village,Pingwu county,Sichuan province,China was surveyed and exemplified to reveal the formation of debris flow fan created by overlapping and accumulating of multiple debris flow torrents;a series of flume experiments equipped with 3D scanning devices and a set of pressure sensors was conducted to measure the phrasal changes of fluid regime in the process of creating a debris flow fan by artificial multiple debris flow release.The genesis of mainstream migration in the fan and resulting debris accumulation shift was examined.(1)Mainstream migration in debris flow fan was controlled mainly by the density of debris flow fluid.The higher density of the fluid,the more possible it was to an overall mainstream deviation;the lower the density,the easier it to form debris body wedging into old underlying fan.(2)The migration occured not quite along lower relief of the fan,but depended mainly on the properties of a following wave of flows.(3)An empirical formula for estimating of deviation angle and distance was proposed in terms of flow density,velocity and fan morphology.The research provides a theoretical basis for understanding the formation,disaster range and evolutionary trend of debris flow fans.
关键词
泥石流堆积扇/叠覆堆积/流态变化/主流偏移Key words
debris flow fan/multi-phase deposition/flow transition/deviation from mainstream引用本文复制引用
基金项目
国家自然科学基金(42271092)
国家自然科学基金(41877261)
中国科学院特别交流计划(E3R5050050)
中国科学院西部青年学者项目(E2R2180180)
出版年
2024
NETL
NSTL
万方数据