Physical Model Experiments of Landslide-Induced Surge in Three Gorges Reservoir
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摘要: 三峡水库自2003年开始蓄水以来, 库岸滑坡变形明显加剧, 滑坡变形不仅造成建筑物破坏, 高速滑坡滑入水库还会产生很大的涌浪, 其潜在的危害性远远超过滑坡本身.2003年7月13日发生在三峡库区的千将坪滑坡就是由水库蓄水诱发所致, 滑坡最高涌浪达到39 m, 在水库传播达30 km之远, 涌浪造成了人员伤亡与财产损失.为了更好地研究水库滑坡涌浪特征和传播规律, 以三峡库区重大科研项目为依托, 采用室内大型物理模拟实验手段, 对三峡库区滑坡涌浪开展了深入研究.通过对三峡库区已经开展勘探的潜在滑坡的地质资料进行统计分析, 按照正交试验设计方法, 制定了包含滑坡规模、入水速度、滑动面倾角、水深、岸坡坡角等综合影响因素的试验方案, 以三峡库区白水河滑坡上下游河道为原型, 建立了1∶200比例尺的河道物理模型, 采用试验控制系统、试验量测系统开展了滑坡涌浪三维物理模型试验.通过细致的物理模型实验, 得到了不同试验条件下的三峡库区滑坡涌浪物理模型实验观测数据.分析滑坡涌浪形态变化, 明确了滑坡最大首浪的含义.在此基础上, 以国内外经典的Noda和潘家铮提出的滑坡涌浪公式为基础, 基于试验量测数据, 提出了三峡库区滑坡涌浪计算公式.最后以三峡库区正在变形的白水河滑坡为例进行了滑坡涌浪预测研究, 预测了滑坡最大首浪高度和沿水库传播的涌浪衰减规律.Abstract: The impoundments of Three Gorge Reservoir have obviously intensified the reservoir bank landslide deformation since 2003. Landslide deformation can cause not only damages, but also evokes great surge once high-speed landslide sliding into reservoir, which is a potential hazard far worse than landslide itself. Owing to the reservoir impoundment, Qianjiangping landslide in Three Gorges Reservoir Area (TGRA) occurred on July 13, 2003. The highest height of landslide-induced surge reached 39 meters which resulted in wave spreading more than 30 kilometers far away along the channel, causing casualties and property losses. In order to study the characteristics and propagation law of landslide-induced surge, based on the major scientific project in TGRA, this paper presenta comprehensive researches on landslide surge hazard in TGRA through large laboratory physical model experiments. Through the statistical analysis of geological data about the potential landslides in TGRA, adopting the orthogonal experimental design method, we formulated the experiment scheme which included landslide scale, speed entering into the water, sliding plane obliquity, water depth, and slope angle. Besides, we took the channel of Baishuihe landslide in TGRA as prototype, established the river physical model in map scale 1∶200, and thus developed landslide surge three-dimensional physical model experiment by adopting the experimental control system and measurement system. According to the careful physical model experiments, we obtained reliable experimental data of landslide surge. Based on the morphological changes of landslide surge, we confirmed the concept of head wave. Then based on the classical landslide surge formulas proposed by Noda and Pan Jiazheng, by analyzing the measured data, we deduced the landslide surge calculation formulas in TGRA. At last, taking Baishuihe landslide being in deformation as an example, these formulas were used to forecast the maximum head wave height and the decay law of landslide surge along the channel.
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表 1 各因素水平
Table 1. Levels of each factor
因素水平 水深(m) 宽度(m) 厚度(m) 长度(m) 速度(m/s) 滑动面倾角(°) 本岸岸坡坡角(°) 对岸岸坡坡角(°) 1 0.5 0.1 0.1 0.1 0.2 5 45 45 2 0.55 0.15 0.15 0.2 0.5 15 / 60 3 0.6 0.2 0.2 0.3 0.8 20 / 70 4 0.7 0.25 0.25 0.4 1.1 25 / 80 5 0.8 0.3 0.3 0.5 1.4 30 / 90 6 0.9 0.35 0.35 0.6 1.7 35 / / 7 1 0.4 0.4 0.7 2 45 / / 表 2 无量纲参数及滑坡横断面河道宽度的范围
Table 2. Ranges of the nondimensional parameters and landslide cross section channel width
v/$ {\sqrt{g h}}$ l/b t/h w/b b(m) 0.064 0.023 0.1 0.023 2.4 0.903 0.292 0.8 0.167 4.3 表 3 河道横断面从本岸向对岸的相对传播距离
Table 3. Relative propagation distance from this bank to opposite bank in river channel cross section direction
水深h(m) 相对距离x(h) 0.5 2.92 3.84 4.5 0.55 2.69 3.44 4.02 0.6 2.53 3.25 3.8 0.7 2.31 2.93 3.4 0.8 2.15 2.69 3.1 0.9 2.03 2.51 2.88 1 2.19 2.62 2.95 表 4 沿程传播浪相对传播距离
Table 4. Relative propagation distance of propagation wave along the channel
水深(m) 相对距离(h) 0.5 4 8 12 18 24 0.55 3.64 7.27 10.91 16.36 21.82 0.6 3.33 6.67 10 15 20 0.7 2.86 5.71 8.57 12.86 17.14 0.8 2.5 5 7.5 11.25 15 0.9 2.22 4.44 6.67 10 13.33 1 2 4 6 9 12 表 5 稳定性计算成果
Table 5. Calculation results of landslide stability
工况 145 m+暴雨 175 m 162~145 m+暴雨 Fs 0.89 0.98 0.85 表 6 滑坡速度与入江规模计算
Table 6. Calculation results of landslide speed and magnitude entering into the water
工况 入江长度(m) 入江宽度(m) 入江厚度(m) 入江速度(m/s) 145 m+暴雨 230.73 475.95 37.08 7.88 175 m 103.51 493.21 24.38 2.75 162~145 m+暴雨 250.07 477.65 35.98 8.71 表 7 滑坡最大首浪与对岸爬坡浪计算
Table 7. Calculation results of landslide head wave and opposite climbing wave height
工况 最大首浪高度(m) 对岸爬坡浪高度(m) 145 m+暴雨 15.4 34.5 175 m 3.6 6.4 162~145 m+暴雨 17.2 38.4 -
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