The present study investigated the effects of clay content and levee's slopes on the breach formation process for levees constructed by both cohesive and non‐cohesive soils. Twelve experiments were carried out and the breach formation of levees was observed by measuring the breach discharge variations and scour topography with time. The initiation of surface erosion was analysed by comparing the estimated bed shear stress and the critical soil shear stress, and the rate of erosion during breaching was estimated by employing the erosion index. The erosion of levees due to overtopping was classified into three regimes of uniform surface erosion, erosion from the toe, and single scour formation. It was found that the upstream levee's slope had negligible effects on the breach process, whereas the downstream slope significantly increased the erosion index. The peak breach discharge increased with increasing downstream slope and it occurred earlier. Experimental results also showed that the peak breach discharge was higher in non‐cohesive levees than the cohesive embankments and it occurred much earlier. Based on dimensional analysis, empirical equations were proposed to predict the breach discharge and the topography of erosion during the breach.

中文翻译：

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上，下游坡度和黏土含量对过顶破坏堤防的影响

本研究调查了黏性土和非黏性土建造的堤防中，粘土含量和堤防坡度对堤防破坏过程的影响。进行了十二个实验，并通过测量违规排放量的变化和随时间的冲刷地形来观察堤坝的违规形成。通过比较估算的床层剪切应力和临界土壤剪切应力来分析表面侵蚀的开始，并通过使用侵蚀指数估算开裂期间的侵蚀速率。堤坝由于过度冲刷而产生的侵蚀分为三种类型，即均匀的表面侵蚀，脚趾的侵蚀和单一冲刷。发现上游堤防坡度对破坏过程的影响可忽略不计，而下游坡度显着增加了侵蚀指数。突峰排放量随着下游坡度的增加而增加，并且发生得较早。实验结果还表明，非粘性堤防中的峰值冲刷流量高于粘性堤防，并且发生时间要早得多。在尺寸分析的基础上，提出了经验公式来预测裂隙放电和裂隙侵蚀的地形。