堰塞坝漫顶溃坝离心模型试验研究

基于唐家山堰塞坝坝料级配曲线,建立相应的物理模型,开展堰塞坝漫顶溃坝离心模型试验,并推导离心场下矩形薄壁堰堰流计算方法。详细分析了堰塞坝漫顶溃坝过程及溃决机理,同时根据试验得出的堰塞坝溃口流量及溃口顶宽发展过程曲线,对溃决机理研究结果做出进一步验证。结果表明:堰塞坝漫顶溃坝过程中,溃口横向扩展贯穿始终,由于大粒径颗粒在下游坝坡的残留,溃口下切发展停止时间较早,溃坝后期下游坝坡存在明显的粗化现象,且堰塞坝溃坝后较少出现全溃的情况,一般都存在一定的残留坝高,其最终溃口尺寸也应小于相同条件下的均质土坝。

Centrifugal model tests overtopping failure of barrier dams

Centrifugal model tests on dam break due to overtopping are carried out based on the gradation curves of Tangjiashan barrier dam by establishing the correspording physical models, and a method for calculating the rectangular weir flow in the centrifugal field is derived. The overtopping process and mechanism of barrier dam is analyzed deeply, and the failure mechanism is verified by the curve of breach flow and the development of breach top width taken from model tests. The test result show that the breach of barrier dam develops throughout during the whole process of overtopping along the width direction. The development of barrier dam breach along the depth direction, however, stops at earlier time due to the accumulation of large particles in the downstream slope, and coarsening phenomenon in the downstream slope can be observed obviously at the later stage of overtopping. Thus, the bottom part of barrier dam will survive after dam break, and the condition of whole collapse has few cases. In addition, the size of breach remaining will be less than that of the homogeneous earth dam under the same condition.