窄深河谷库岸滑坡坝前涌浪特性及浪高影响因素

Surge characteristics and influence factors of wave height of landslide near the dam in a narrow deep valley

为研究窄深河谷中近坝库区发生整体大方量失稳时次生涌浪在坝前区域的涌浪特性及影响因素,依托1:100物理模型开展窄深河谷近坝库区滑坡涌浪模型试验,研究坝前区域有较大越浪风险的坝肩测点的首浪高度和最大浪高,重点对比分析入水方量、入水速度对首浪高度和最大浪高的影响规律;并以量纲分析为基础,通过非线性回归分析得到坝肩位置的浪高预测公式。结果表明:坝前各点涌浪变化趋势相近,坝前区域的最大浪高几乎都出现在右坝肩的位置,具有更大的翻坝风险;在试验工况范围内,首浪高度随入水方量的增加有明显增加;滑块方量比入水速度对浪高的影响更大,且首浪高度比最大浪高对方量变化、入水速度变化的敏感性更高;坝前区域右坝肩的首浪高度、最大浪高对滑块宽度(方量)变化的平均敏感度系数分别为0.858、0.358,对入水速度变化的平均敏感度系数分别为0.217、0.115。依据试验成果拟合的浪高预测公式:首浪高度预测一致性较好,其预测误差低于3%;最大浪高波动随机性较大,预测误差小于15%。

A model experiment is one of the most effective and important ways to study landslide surge in a reservoir.A large-scale model can usually help obtain more reliable results.Therefore,to investigate the characteristics of a surge in front of a dam and its contributing factors,especially when the whole volume of unstable landsides is relatively large,a physical model with a scale as large as 1:100 was built up to simulate the topography of the reservoir in a narrow deep valley.Furthermore,the generation and the propagation of the landslide surge in the reservoir and near the dam were studied by utilizing the rigid sliding blocks.It is found that the shoulders of the dam have the most probable risks of overtopping.The height of the initial surge wave and that of the maximal wave were investigated.The influences of different volume of the sliding blocks,as well as the entry velocity on the heights of the surge wave were compared and analyzed.Furthermore,a formula to predict the surge wave height on the shoulders of the dam is proposed by nonlinear regression based on dimensional analysis.It is shown from the experimental results that although the trend of surge wave heights in front of different gauging points is similar,the maximal wave heights usually occurred near the right shoulder of the dam,so it possesses more risks of overtopping.In addition,the influence of the volume of the sliding blocks on the wave heights is larger than that of the entry velocity.The initial wave height is more sensitive to the volume and entry velocity of the blocks than the maximal one.The mean sensitivity to the volume of the blocks on the initial and maximal wave height at the right shoulder of the dam is 0.858 and 0.358,respectively,while the mean sensitivity to the entry velocity is 0.217 and 0.115,respectively.The difference between the predicted results from the fitting formula and the experimental data for the initial wave height is less than 3%,indicating that the fitting formulae for the initial height have great accuracy and consistency.On the other hand,the maximal surge wave height has larger randomness,with the difference between the predicted results and the experimental data being less than 15%.