水库滑坡涌浪动压力特征试验研究

Experimental Research on Dynamic Pressure Characteristics of Reservoir Landslide-induced Surge

水库滑坡高速入水产生涌浪,当涌浪传播到对岸岸坡时,巨大的冲击力会造成沿岸基础设施的破坏,对沿岸居民的生命和财产安全构成极大威胁。为研究水库滑坡涌浪冲击力在对岸岸坡上的作用特点及其分布规律,以三峡库区中等宽缓库段滑坡及河道规模为原型,开展了1∶400比例的三维正态滑坡涌浪物理模型试验,初步揭示了水库滑坡涌浪动压力的类型、不同类型动压力的作用特点及其分布规律。结果表明:根据试验测试数据,滑坡涌浪形成后以水舌和实体涌浪两种水体形态作用在岸坡上,作用在岸坡上的水库滑坡涌浪动压力可分为水舌冲击压力和涌浪脉冲压力两种类型,水舌以射流的形式冲击岸坡,产生瞬时冲击压力极大值,实体涌浪在岸坡上爬高产生多个脉冲压力值,涌浪最大脉冲压力出现在前三个压力峰值;在静水面以上,水舌冲击压力大于涌浪脉冲压力,而在静水面以下,出现水舌冲击压力小于涌浪脉冲压力的情况;滑坡涌浪脉冲压力在岸坡上的分布近似为倒“V”型,涌浪最大脉冲压力出现在静水位附近且随着涌浪爬坡高度的增加呈快速衰减到缓慢衰减的过程,在快速衰减阶段滑坡涌浪脉冲压力极值的累计衰减率往往超过60%。

Landslide entering reservoir with high speed causes damage to coastal infrastructure when the surge spreads to the opposite bank slope,which greatly threatens the lives and property of coastal residents.In order to study the characteristics and distribution of dynamic pressure of landslide-induced surge on the opposite bank slope of reservoir,this study takes the landslide and river channel in the medium-wide section of Three Gorges Reservoir as prototype,carries out a three-dimensional normal physical model test with a scale of 1∶400,and preliminarily reveals the types,characteristics and distribution of dynamic pressure of surge induced by landslide.The results show that according to the test data,the landslide-induced surge acts on the bank slope in two water shapes,i.e.water tongue and surge wave,and the dynamic pressure of landslide-induced surge acting on the bank slope can be divided into impact pressure and impulse pressure which are caused by water tongue and surge wave separately.Water tongue impinges on the bank slope in the form of a jet and produces the maximum instantaneous impact pressure.Surge wave generates several impulse pressure and the maximum impulse pressure appears in the first three pressure peaks.Above the static water surface,the impact pressure of water tongue is greater than the surge impulse pressure,but the impact pressure of water tongue may be less than the impulse pressure under the static water surface.The distribution of impulse pressure on the bank slope shows approximately the inverted“V”shape.The maximum impulse pressure appears near the static water surface.The attenuation process of impulse pressure changes from rapid attenuation to slow attenuation with the increase of climbing height of surge.The attenuation rate of extreme value impulse pressure in the rapid attenuation stage is often more than 60%.