| 摘要: |
| 基于物理模型试验，建立堰塞体渗透破坏模型，研究堰塞体因渗透破坏导致坝体坍塌最终漫顶溃决全过程发展机制，从坝料颗粒级配、初始渗透通道位置、坝体密实程度三方面着手开展研究。研究结果表明：在不发生漫顶的前提下渗透通道的坍塌一定程度上延缓了溃坝进程；在渗透通道发展过程中，坝体内部特别是渗透通道上方容易出现裂缝，漫顶溃决水流掏刷侵蚀坝体的能力强于渗透侵蚀破坏；在渗透通道即将失稳坍塌到坍塌之后较短的时间段内水流冲蚀坝体的效率最高，溃口发展最剧烈，流量增长速度最快且会出现峰值流量；溃口流量在减小的过程中会出现偶尔会增大的现象，是由溃口边坡间歇性失稳坍塌导致溃口宽度突增而引起的；初始渗透通道位置对堰塞体渗透破坏溃决流量具有较大影响，其中水平向位置影响最大(初始渗透通道靠近坝体中部时的溃决流量大于靠近两岸时的溃决流量)，垂直向位置影响相对较小；坝体密实程度大的溃口峰值流量出现时间晚，渗透通道存在的时间相对更久；若没有超大粒径，溃口底部在水流冲刷作用后较为平整；在一定级配范围内，若组成堰塞体的土石料颗粒小，则溃口宽度相对偏大，级配对溃口深度的影响较小；同高程不同水平位置的渗透通道对溃口发展规律的影响不同，若初始渗透通道靠近两岸，则溃口发展较缓且溃口最终宽度较小，若初始渗透通道靠近坝体中部，则溃口发展相对更剧烈且溃口最终宽度更大；不管初始渗透通道是水平向还是竖直向对比，都有一个共同点即溃口宽度大则溃口深度小，溃口宽度小则溃口深度大，究其原因，应是在水流条件、蓄水量、级配等其他条件相同的前提下，溃口在发展的过程中需要足够的过水断面来支持水流下泄，因此溃口宽度和深度呈负相关。 |
| 关键词: 堰塞体 渗透破坏 渗透通道 试验研究 溃决机理 |
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| 基金项目:国家自然科学基金（52279095）；国家自然科学基金（52109149）;重庆市科委基础研究与前沿探索项目（cstc2021jcyj-msxmX0155） |
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| Experimental Study on the Seepage Failure Mechanism of Landslide Dam |
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Zhao Tianlong, Zhang Chuan, Fu Changjing, Yue Liang, Bi Yuan
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Hehai Institute Chongqing Jiaotong university
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| Abstract: |
| Based on the physical model tests, the model of seepage damage of the landslide dam is established to study the development mechanism of the whole process of dam collapse due to seepage damage, based on the three aspects of dam material gradation, initial seepage channel location, and the degree of dam density. The results of the study show that: the collapse of the seepage channel without the occurrence of overtopping delays the process of dam failure in some degree; during the development of the seepage channel, cracks tend to appear inside the dam body, especially above the seepage channel; the ability of the overtopping breach water to erode the dam body is stronger than the damage by seepage erosion; the water erosion of the dam body is most efficient during the short period between the imminent failure of the seepage channel and the collapse; and the development of the breach is the most intense. The most rapid development and the fastest growth rate of flow and peak flow will occur, and the occasional increase in breach flow in the process of reduction is caused by the intermittent destabilization of the breach slope, resulting in a sudden increase in breach width; the location of the initial seepage channel has a large influence on the weir seepage damage breach flow, with the horizontal location having the greatest influence (the breach flow when the initial seepage channel is near the middle of the dam body is larger than the breach flow when it is near the banks). If there are no oversized grains, the bottom of the breach is flatter after water scouring; within a certain grading range, if the grains of soil and rock that make up the weir are small, the width of the breach is relatively large, and the influence of the grading on the depth of the breach is smaller If the initial infiltration channel is close to the two banks, the development of the breach is slower and the final width of the breach is smaller. If the initial penetration channel is close to the middle of the dam, the development of the breach is relatively more intense and the final width of the breach is larger. Regardless of whether the initial infiltration channel is horizontal or vertical, all have one thing in common, i.e. a larger breach width results in a smaller breach depth . This is due to the fact that, under the same conditions of water flow, water storage, and grading, the breaches need a sufficient overflow section to support the water flow during development, so the breaches are negatively correlated in width and depth. |
| Key words: landslide dam seepage failure seepage channel experimental study failure mechanism |
