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泥石流沟道的沿程侵蚀特征及演进过程研究
Alternative TitleStudy on erosion characteristics and routing of debris flow along the channel
Language中文
朱兴华
Thesis Advisor崔鹏
2013
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Name博士
Degree Discipline岩土工程
Keyword泥石流 沟床冲刷 侧蚀 级联溃决 规模放大
Abstract对于完整的泥石流沟段,泥石流在沿沟道运动过程中将沿程受到沟床物质冲刷,沟岸侧蚀以及堵塞体的冲刷输移这样三种物源补充,从而使得泥石流能够从上游的涓涓细流,不断发展壮大,孕育出大型甚至特大型泥石流灾害。本论文以我国西部山区近年来发生的大型泥石流灾害为研究原型,通过详细的野外考察,凝练研究模态,并以理论分析,模型实验以及数值计算等研究方法相结合,对泥石流沿沟道的沿程侵蚀特征及演进规律进行了探索。主要内容如下:(1)详细考察了舟曲8.8泥石流以及绵竹8.13泥石流灾害。由于传统的形态调查法中,有关糙率系数取值的不合理性,本研究首先修正了泥石流糙率系数的计算方法,将泥石流糙率划分成外部糙率和内部糙率;然后结合详细的野外测量,以修正的曼宁公式反演分析了大型泥石流灾害的沿程演进过程,并根据演进过程中所对应的侵蚀物源分布情况,凝练了泥石流沿程侵蚀的物理模态。(2)研究了泥石流沟道中堆积物的起动及输移规律。考虑到床面粗化层形成及破坏对泥石流输沙过程的影响,引入了粗化层形成及破坏的临界条件,将泥石流的水动力条件划分成粗化层不能形成,粗化层形成但不被破坏以及粗化层形成并被破坏三个区间,对应了三种不同的冲刷输移模式,并分别理论推导了各自的输沙率计算方法。然后通过野外沟道实验数据率定了计算公式中的待定参数,并通过大型水槽实验数据对计算公式进行了检验和校正。(3)探索了泥石流沟岸侧蚀机制。分析了泥石流沟岸侧蚀的特点及过程,包括岸脚掏蚀,拉裂面的形成,沟岸失稳以及失稳土体的冲刷输移这样四个阶段。然后以理论分析和野外模型实验相结合,提出了沟岸侧蚀的输沙率计算方法。(4)分析了堵塞体溃决过程及其对泥石流规模放大的影响。沟道中的天然坝体可分为半堵型和全堵型两种类型。本论文首先探讨了单一的半堵型堵塞体和全堵型堵塞体溃决过程及溃决流量时变特征,并提出了计算溃决峰值流量的理论模型和经验模型。然后通过模型实验分析了级联溃决条件下,泥石流峰值流量规模的逐级放大效应。(5)结合三种物源的侵蚀速率以及堵塞体对峰值流量的调控机制,提出了泥石流峰值流量沿程演进的计算流程。
Other AbstractFor a section of complete debris flow channel, the debris flow will be supplied with three kinds of source materials including: channel bed erosion, channel lateral erosion and landslide dams’ failure when it flows along the channel.In this paper, the catastrophic debris flow hazards in western China were taken as research prototypes, 6 kinds of erosion modes were presented after detailed field investigation about the disasters mentioned above. What’s more, the erosion characteristics and routing of debris flow along the channel was explored by model experiments and numerical simulation. The main contents are as follows: 1.Detailed field investigation about the “8.8” Zhouqu debris flow and “8.13” Mianzhu debris flow. As the selection of Manning roughness coefficient was of subjectivism, which cause the calculation of debris flow velocity always had a big error comparing with the observations. In this research, the calculation of Manning roughness coefficient was amended at first. And then, 6 kinds of erosion modes were presented by back analysis of the routing process of two debris flows mentioned above. 2.Research on the sediment delivery of debris flow. The process of armoring should be considered in the initial erosion of non-uniform channel bed material. Therefore, the erosion process of non-uniform channel bed material sourced by debris flow can be classified as three modes according to ctitical criterion of amoring layer. The value of erosion coefficient was also explored according to field flume experiments. In addition, the formula used to calculate sediment delivery was revised according to the experimental data of large-scale flume experiments. 3.The mechanism of channel laterial erosion was explored. The process of laterial erosion can be devided into four stages: channel bank toe erosion, the formation of tension crack, the failure of channel bank and sediment delivery of failed channel bank. And then, the sediment delivery rate of channel laterial erosion was presented according to theoretical analysis and model experiments. 4.The scale amplification of natural debris flows caused by cascading landslide dam failures is analyzed. The landslide dams in debris flow channel can be classified as fully blocked dams and partial blocked dams. In this paper, the failure process of single dams and breach discharge curve was explored at first. In addition, we analyzed the scale amplification of natural debris flows caused by cascading landslide dam failures by flume experiments. 5.In consideration of the erosion rate of three kinds of source materials and scale amplification of natural debris flows caused by landslide dam failure, the calculation procedure of peak discharge along the channel was presented.
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/7061
Collection山地灾害与地表过程重点实验室
Recommended Citation
GB/T 7714
朱兴华. 泥石流沟道的沿程侵蚀特征及演进过程研究[D]. 北京. 中国科学院研究生院,2013.
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