堰塞坝连续溃决对泥石流规模放大效应影响研究

发布时间：2018-07-15 08:14

【摘要】：泥石流灾害现在已经成为我国重大的地质灾害之一,这种灾害会引起堵塞江河、掩埋村庄及摧毁建筑厂矿的危害,造成了重大的经济损失和人员伤亡。泥石流指的是山区或者沟谷深壑的险峻地区,暴雨、暴雪等自然灾害引发山体滑坡并且携带有大量泥沙及石块的特殊洪流。如果流入沟道内的山洪引发了堰塞坝的连续溃决,坝体连续溃决的洪流会使泥石流的规模放大,非常容易在很短的时间内造成特大泥石流灾害。本文以七盘沟和舟曲泥石流为例,地震触发了大量的崩塌、滑坡等地质灾害,这些堆积体在沟道内形成大量的堵塞坝。2013年7月10日,汶川县七盘沟由于大暴雨而引发洪流,上游洪水先造成支沟堰塞坝溃决,产生的突发性高强洪水再使主沟的坝体溃决,最后造成特大泥石流灾害。研究堰塞坝连续溃决的过程及对泥石流规模的放大效应,对于研究泥石流的定性危害具有重要的科学理论意义,更对连续溃决型泥石流的治理具有实际应用价值。本文是在野外勘查的基础上,运用野外泥石流堆积体为研究对象,以室内物理试验方法,深入研究堰塞坝连续溃决对泥石流规模的放大效应,其中主要研究坝体的初始含水率颗粒级配、水槽坡度和坝体颗粒机配对放大效应的影响,最后得出了以下成果和认识:(1)当上游堰塞坝发生溃决,会产生大量的涌动洪水,并增加沟道内的物质的势能,增大转化而成的流体的动能,致使坝体连续溃决而造成泥石流规模放大,形成特大泥石流灾害。(2)堰塞坝的连续溃决中,坝体的溃决破坏形式为漫顶溃决,其中为瞬时漫顶溃决,溃决洪水会对坝体进行过坝冲刷侵蚀,坝体坡面整体侵蚀,历时短,坝体几乎无渗透和管涌作用。(3)根据不同水槽坡度的堰塞坝连续溃决试验,当水槽坡度为5°时,坝体的溃决能量的放大倍数约2倍,泥石流规模的放大效应不是特别大;当水槽坡度为18°时,连续的溃坝能量放大比例更大,泥石流规模的放大效应也比较明显。(4)坝体的材料对堰塞坝连续溃决造成的泥石流规模有一定的影响,其中对于不同含水情况的坝体,在泥石流来流的冲刷下,初始含水率越大的坝体,溃决能量的放大倍数越高,泥石流规模的放大效应越明显。(5)坝体的级配特征以粒径中值D50和不均匀系数Cu为参考值,随着D50的增大,不均匀系数也在增大,溃决能量的放大倍数最大,对泥石流规模的放大效应影响更大。说明粒径中值较大的坝体连续溃决对泥石流规模的放大效应是明显的。
[Abstract]:Debris flow disaster has become one of the major geological disasters in China, which will cause the damage of blocking rivers, burying villages and destroying construction factories and mines, resulting in great economic losses and casualties. Debris flow refers to steep areas in mountainous areas or deep gullies. Natural disasters such as torrential rain, heavy snow and other natural disasters cause landslides and carry a large amount of sediment and rocks. If the mountain torrents flowing into the channel cause the continuous collapse of the dam and the dam, the continuous collapse of the dam body will enlarge the scale of the debris flow, and it is easy to cause the catastrophic debris flow disaster in a very short time. Taking Qipangou and Zhouqu debris flow as examples, the earthquake triggered a large number of geological disasters, such as collapses and landslides, which formed a large number of blocked dams in the channel. On July 10, 2013, Qipangou, Wenchuan County, was flooded by torrential rain. The upstream flood caused the break of the dam first, the sudden high strength flood caused the dam body of the main ditch burst, and finally caused the huge debris flow disaster. It is of great scientific and theoretical significance to study the process of continuous collapse of dam and Weir dam and its magnification effect on the scale of debris flow. It is also of practical application value to control the debris flow of continuous collapse type. This paper is based on the field exploration, using the debris flow accumulation in the field as the research object, using the indoor physical test method to study the amplification effect of the continuous collapse of the Weir, plug and dam on the scale of the debris flow. The effects of initial water content particle gradation, flume gradient and granulation machine on magnification effect of dam body are studied. Finally, the following results and understandings are obtained: (1) when the upstream dam collapses, a large number of inrush floods will occur. And increase the potential energy of the material in the channel, increase the kinetic energy of the transformed fluid, cause the dam body to burst continuously and cause the scale of debris flow to enlarge, and form the huge debris flow disaster. (2) during the continuous collapse of the dam, The failure form of dam body is overtopping, which is instantaneous overtopping outburst. The burst flood will erode the dam body through the dam, and the whole slope of the dam body will erode for a short time. (3) according to the continuous break test of Weir and plug dam with different flume slope, when the flume slope is 5 掳, the magnification of collapse energy of dam body is about 2 times, and the amplification effect of debris flow scale is not especially large. When the slope of flume is 18 掳, the energy amplification ratio of continuous dam break is larger, and the amplification effect of debris flow scale is also obvious. (4) the material of dam body has certain influence on the scale of debris flow caused by continuous collapse of dam and dam. For the dam with different water content, under the erosion of debris flow, the larger the initial water content, the higher the magnification of breaking energy. The larger the scale of debris flow is, the more obvious the scaling effect is. (5) the gradation characteristics of the dam body take the median particle size D50 and the non-uniform coefficient Cu as the reference values. With the increase of D _ (50), the non-uniform coefficient is also increasing, and the magnification of breaking energy is the largest. The amplification effect on the scale of debris flow is more important. The results show that the amplification effect of continuous collapse of dam body with large median particle size on the scale of debris flow is obvious.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P642.23

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