堰塞坝漫顶溃决过程溃口纵向下切与溯源

为进一步了解堰塞坝溃坝过程，开展了9组水槽模型试验，对溃口纵向下切和溯源发展过程进行了系统分析，并讨论了上溯源点移动速度与溃口水深之间的关系。研究发现：非黏性堰塞坝溃坝过程中，冲刷面与底床的夹角时刻发生变化，上、下溯源点位置不固定但也不能完全发展到坝踵；上、下坡面坡度增大到最大值1：1.5时，下溯源点到下游坝趾的最大距离与坝体沿水流方向长度的比值（x_p^*/x_d^*，反映下溯源点最终相对位置）对应降低到最小值0.24和0.18；坝体相对尺寸从1减小到1/2时，x_p^*/x_d^*值从0.38增大到0.47。上溯源点的无量纲移动速度是不断变化的，在无量纲时刻为0.13时，其x，y分量分别达到峰值0.94和0.32；上溯源点处溃口水深出现时刻相对移动速度峰值点出现时刻有延迟，大概延迟0.04个无量纲时间。

Depth Erosion and Tracing of Overtopping Landslide Dam Breach

In order to understand the failure process of landslide dam, nine sets of flume model experiments were conducted, the depth erosion and tracing of dam breach was further discussed, and the relationship of moving velocity of up-tracing point and breach depth was also analyzed. The results indicated that the angles between the erosion layer and the base bed were changing during the dam failure of non-cohesive landslide dam; The locations of up-tracing and down-tracing point were unfixed,but they could not move to the dam heel; When the slope of the upstream and downstream face slope increased to a maximum of 1:1.5, the ratio of the maximum distance from down-tracing point to downstream toe of the dam to the length of the dam along the flow direction (reflecting the final relative position of the down-tracing point) was correspondingly reduced to the minimum values of 0.24 and 0.18; When the relative scale of the dam reduced from 1 to 1/2, the value of x_p^*/x_d^* was correspondingly increased from 0.38 to 0.47. The dimensionless moving velocity of up-tracing point was constantly changing; There was a time delay of the peak breach water depth relative to the peak moving velocity, and the dimensionless delay time was about 0.04.