水库土石坝阶梯式上游护坡消浪效果数值模拟研究

Numerical Simulation of Wave Elimination Effect of Upstream Stepped Slope Protection for Reservoir Dam

阶梯式护坡在满足一定人文景观需求的同时具有较好的消浪效果,近年来已应用在部分堤坝工程中,但目前依然缺乏相关设计参数的系统研究。针对中大型水库土石坝工程,基于速度边界法建立二维波浪数值模型,分析了台阶布设范围、台阶尺寸、坝坡坡度、波坦等因素对波浪爬高的影响。研究结果表明:相较于光滑斜面护坡,阶梯式护坡可以有效减小波浪爬高;在同一波坦及坝坡坡度情况下,波浪爬高随台阶布设范围的增大呈减小趋势,随台阶高度的增加有先减小再增大的趋势;推荐台阶布设范围为自由水面以上1倍波高至自由水面以下2倍波高,推荐台阶高度为入射波高的0.4倍,其波浪衰减系数在60%至70%之间。在推荐阶梯式护坡布置形式下,波浪爬高随入射波坦的增大而增大,随坝坡坡比变缓而减小,当坝坡缓于1∶3.0时,坡度系数对波浪爬高的影响有所减弱。根据推算的综合糙渗系数,可初步估计阶梯式护坡波浪爬高,为类似工程设计提供参考。

Stepped slope protection can not only meet the needs of cultural landscape, but also has a good effect of reducing waves. In recentyears, it has been applied in some dam projects, but there is still a lack of systematic research on relevant design parameters. In this paper,a two⁃dimensional numerical wave model was established based on the velocity boundary method according to the medium and large reservoirdams. The influence of step layout range, step size, dam slope degree and wave smoothness for wave run⁃up was analyzed. The results showthat, compared with the smooth slope protection, the stepped slope protection can effectively reduce the wave run⁃up. For the same wavesmoothness and dam slope degree, the wave run⁃up decreases with the increase of step layout range, and decreases first and then increaseswith the increase of step height. The recommended step layout range is 1 times the wave height above the free water surface to 2 times thewave height below the free water surface. The recommended step height is 0.4 times of the incident wave height, and the wave attenuation co⁃efficient is between 60% and 70%. In the recommended stepped slope protection arrangement, the wave run⁃up increases with the increase ofwave smoothness and decreases with the softening of dam slope. When the slope is lower than 1 ∶ 3.0, the influence of slope coefficient onwave run⁃up weakens to some extent. According to the comprehensive roughness and osmosis coefficient calculated in this paper, the waverun⁃up of stepped slope protection can be estimated preliminarily, which provides reference for similar engineering design.