IMHE OpenIR  > 山地灾害与地表过程重点实验室
堰塞坝漫顶溃决实验研究
Alternative TitleExperimental study on the overtopping process of landslide Dam
刘定竺
Subtype硕士
Thesis Advisor崔鹏
2017
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline岩土工程
Keyword堰塞坝 漫顶溃决 展宽侵蚀 溯源侵蚀
Abstract大地震诱发的大量次生山地灾害(崩塌、滑坡、泥石流等)堵塞河道后很容易形成堰塞坝,随着上游来水,很容易发生漫顶溃决形成危害极大的次生灾害。本文研究堰塞坝的漫顶破坏过程,以加深对溃决过程的认识。实验包括室内水槽实验以及相对应的坝体物料土工实验;室内水槽实验研究不同坝后坡降、坝长、坝高、来流量情况下的溃决过程;土工实验包括测量坝体材料的比重、休止角、含水率。堰塞坝纵向发展过程分为四个阶段,分别为渗流阶段、缓慢侵蚀阶段、溯源侵蚀阶段以及形成稳定河床阶段对应不同的侵蚀以及能耗特征。第一阶段渗流力消耗水能;第二阶段粗颗粒在渗流的作用下会加快沉积而形成的堆积体,减缓水流的纵向侵蚀,加强水流的侧向侵蚀;粗颗粒的存在增大了河床惯性加强水能的紊动消耗,溃口形态发展同溯源方程描述的演变方式不同,同时分析了该方程的适用范围;第四阶段下泄流量变大,水沙作用增强,溃口急剧发展,水沙作用逐渐平衡。展宽过程可分为近等宽阶段以及弯曲阶段。断面展宽可分为线性模式和突变模式,突变模式可进一步分为弱侵蚀过程与强侵蚀过程,强侵蚀过程只发生在弯曲阶段。突变模式下,弱侵蚀过程的展宽侵蚀率沿程呈 “U”型分布,当坝后坡比越大,坝顶相同位置的展宽侵蚀率越大。强侵蚀过程的展宽侵蚀率呈“S”型分布;坝长较短的情况下,两个阶段的侵蚀率沿程都呈 “U”型。坝高越高、坝后坡降越小,溃口平均展宽侵蚀率越大。来流越大溃决历时越短,溃口发展越快。展宽侵蚀率受侧壁抗侵蚀能力、水流作用强度和时间、水流流态等因素综合影响。在低水流强度时,溃口竖直展宽,而高水流强度时多发生崩滑,侧壁非垂直。溃口的横向展宽分为两个步骤:水流侵蚀破坏底部骨架,上部发生坍塌。底部骨架破坏存在骨架破坏切应力以及临界功率,该临界状态同颗粒组成、过流水深、坡降、宽深比有关系。侧部展宽向底部侵蚀存在正补馈机制,侧部泥沙的运动性质不同于悬移质以及输移质。在溯源侵蚀作用范围的上游段,结合王兆印提出的清水侵蚀率公式,计算出的底部的切应力以及水能功率较侧部大,底部功率比侧部大10%左右。对比侧向展宽侵蚀率以及侧部功率,发现二者有很好的线性关系,结合量纲分析,展宽公式存在两种形式:E=K(P-Po)以及Sr=K'(P-Po);将侧部功率除以平均流速得到的侧部切应力同侧部展宽率也具有较强的线性关系;这些方程的斜率以及截距同坡降、宽深比以及颗粒本身物理性质等因素有关,成熟的侵蚀率公式应是三元流的方程。
Other AbstractEarthquakes cause a large number of secondary mountain disasters (collapse, landslides, debris flow, etc.) which plug the river and is easy to form a dam, with the upstream flow, it is easy to form a great threat to human. This paper studies the overtopping process of landslide dam aim at deepen the understanding of the process. The experiment includes the indoor flume experiment and the corresponding soil engineering experiment of the dam. The indoor flume experimented with the failure process of different slope, length, height and flow rate. The geotechnical experiment included measuring the proportion of the dam material, Angle, moisture content.The study indicated that the broadly graded landslide dam include 4 stages: Seepage Stage, Slow Erosion Stage, Retrogressive Erosion Stage, Stable Stage. Every stage has its character of erosion process and energy dissipation. The energy dissipation in the 1st stage is mainly in seepage force;coarse granule will be deposited quickly in the 2ed stage due to seepage;Coarse particles increases the riverbed inertia, it makes the turbulent water consumption to strengthen the response, erosion and transport of bedload burst shape changes due to energy consumption is diversity; the fourth stage discharge becomes strong and the mechanics between water and sediment enhanced, breach developed rapidly, and becomes stable in the last.Broadening process can be divided into “Weak Aequilatus Stage” and “Bending Stage”. For the sections, the widening process can be divided into Linear Mode and Mutation Mode, the Mutation Mode can be further divided into Weak Erosion ProcessⅠand Strong Erosion Process Ⅱ, in which strong erosion processⅡoccurs only in the Bending Stage. The first process of broadening rate along the breach looks like "U", when the dam slope is higher and slope is smaller broadening rate is larger. The second process of the broadening erosion rate along the breach looks like "S", when the higher dam height and smaller dam slope there is the smaller the average erosion rate. In the case of short dam length, the erosion rate of the two stages is "U" type. The greater flow leads to shorter break history, and breach develops faster. The rate was influenced by side erosion resistance, the erosion time of water flow, and the flow pattern.At low water flow intensity, the breach is broadened in the vertical case, and landslides occur when the water flow in high intensity and the sidewalls are not vertical. Breach broadening can be divided into two steps: flow destroys the bottom skeleton and the upper part collapses. The bottom skeleton is eroded in critical condition which is related to PSD, water depth, slope, depth to width ratio. Side is a positive feedback to the bottom, and the properties of side are different from that of the suspended matter and the transport. In the upstream section of the retrogressive erosion, combined with the water erosion rate formula proposed by Wang Zhaoyin, the calculated shear stress and water power of the bottom are larger than side, and the bottom power is about 10% larger than the side. Comparing lateral erosion rate and the side power, there is a good linear relationship between them. In combination with the dimensional analysis, the broadening formula has two forms: E=K(P-Po) and Sr=K'(P-Po); the lateral shear stress obtained by dividing the lateral power by the average flow rate also has a strong linear relationship with width-erosion-rate. The slope and the intercept of these equations are related to the factors such as slope, width and depth ratio and the physical properties of the particles themselves. Mature erosion rate formula should be the equation of three-dimentional-flow, which can reflect the influence of different momentum conditions on erosion. 
Pages72
Language中文
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/24572
Collection山地灾害与地表过程重点实验室
Affiliation中国科学院成都山地灾害与环境研究所
First Author Affilication中国科学院水利部成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
刘定竺. 堰塞坝漫顶溃决实验研究[D]. 北京. 中国科学院大学,2017.
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