土石坝漫顶过程水力特性分析

Overtopping hydraulic characteristics of earth-rock dam

土石坝漫顶过程极其复杂，溃决过程研究成果存在诸多争议。采用标准k-ε紊流模型和VOF方法对土石坝水流漫顶过程进行了水气两相流数值模拟，对漫顶过程水流流念、流速分布等进行了详细分析，揭示了坝面切应力分布规律。该规律的发现可以用于解释笔者先前提出的“落点冲蚀”猜想及“剪剥式”冲蚀理论，即漫顶条件下最先发生冲蚀的部位可能在坝坡中上部，漫顶冲蚀以台阶式冲蚀为溃决的主要特征。

The dam breach formation under overtopping condition is very complex and there are many disputes about it. In the paper, the k-ε turbulence model was used to close Reynolds time-averaged equation and the volume of fluid （VOF） method was used to track the free face. The numerical simulation model was used for analysis the flow pattern and the velocity distribution on the surface of earth-rock dam due to overtopping in detail. The results show the shear stress distribution rules on the surface of dam, which can be used for explaining why the first erosion place may be appeared at the upper part of dam and the stepped erosion is the mainly form.