堰塞坝漫顶溃决过程数值模拟

根据堰塞坝坝体材料的宽级配特性,建立描述堰塞坝漫顶溃决溃口发展规律与流量过程的数值模型。该模型引入与水流方向垂直的附加作用力来考虑粗颗粒对细颗粒的阻拦和遮蔽作用以及细颗粒对粗颗粒的包围和填实作用。基于不同土体陡水槽冲蚀试验结果,针对宽级配堰塞坝材料在高强度水流侵蚀条件下的冲蚀特性,建议采用能反映坝体材料颗粒级配、密实度、强度、坝体坡度、水流速度及摩阻流速对冲蚀量影响的土体冲蚀公式。利用该数值模型对唐家山堰塞坝溃决案例进行计算分析,所得溃坝洪水流量过程与实测结果接近,验证了该模型和计算方法的合理性,表明该模型能准确反映水库库容和上游补给水流量对堰塞坝漫顶溃决发展过程的影响。

Numerical simulation of overtopping failure process of a barrier dam

Based on the wide gradation characteristics of barrier dam materials,a numerical model describing the discharge process and breach development due to overtopping failure of a barrier dam is proposed.Additional force that is perpendicular to the water flow direction was introduced into the model to consider the block function and bridging effect of coarse particles on fine particles,and the way in which fine particles surround and fill coarse particles.Based on the results of steep sink tests of different soils and erosion characteristics of the barrier dam materials with wide gradation under high strength water conditions,a formula was put forward to calculate the erosion of dam materials during the dam break process.The formula can reasonably reflect the influences of gradation,compactness,strength of dam materials,dam slope,flow velocity,and friction velocity on the erosion quantity.The proposed model was used to calculate and analyze the break of the Tangjiashan Barrier Dam.The calculated result of the flood discharge process was close to the observed one,indicating that the model and the calculation method were reasonable and could exactly reflect the influences of the reservoir capacity and recharge water from upstream on the overtopping failure of the barrier dam.