Abstract: According to the characteristics of gravel transportation in the process of landslide dam break, three categories of seven groups of wide graded gravel were designed. The first category consisted of two groups of uniform gravel with particle size of 4 mm and 5 mm respectively, and the second one consisted of four groups of non-uniform gravel with maximum particle sizes of 20, 37.5, 53 and 75 mm respectively, and the third one was non-cohesive non-uniform gravel with the maximum particle size of 20 mm. Four groups of test flow conditions including constant flow A and B as well as non-constant flow C and D, and two types of tail-gate opening I and II were selected. A total of 25 groups test conditions were carried out. The flume scour test of wide graded gravel was carried out. The influence rule of discharge process, downstream discharge conditions and grading width of gravel on the scour characteristics of gravel was compared and analyzed. The results show that: for the non-cohesive gravel, the transportation of gravel under non-constant flow is more active than that under constant flow, which is characterized by large scouring and silting. The larger the opening of the tail-gate is, the better the downstream discharge conditions are, the more severe the scouring of gravel is, and the greater the scouring amount is. With the increase of the grading width of gravel, the position of the gravel with the largest scouring depth in the flume is gradually close to the downstream position of the flume, and the scouring amount decreases continuously.

Key words: hydraulic engineering, non-constant flow, gravel, wide graded, flow process, tail-gate opening

摘要： 针对堰塞坝溃决过程中土石料输移特性，设计了3类共7组宽级配土石料：第1类为2组粒径分别为4、5 mm的均匀土石料，第2类为4组最大粒径分别为20、37.5、53及75 mm的非均匀土石料，第3类为最大粒径为20 mm的无黏性非均匀土石料；选择了恒定流A、B及非恒定流C、D共4组试验水流条件，以及2种尾门开度Ⅰ、Ⅱ，共25组试验工况；开展了宽级配土石料水槽冲刷试验，对比分析了流量过程、下游泄流条件、土石料级配宽度对土石料冲刷特性的影响规律。研究表明：对于不含黏性颗粒的土石料，非恒定流条件下的土石料输移相较于恒定流条件下的更加活跃，表现为大冲大淤；尾门开度越大即下游泄流条件越好，土石料的冲刷越严重，冲刷量越大；随着土石料级配宽度的逐渐增大，土石料冲刷深度最大的位置逐渐靠近水槽下游位置，冲刷量不断降低。

关键词: 水利工程, 非恒定流, 土石料, 宽级配, 流量过程, 尾门开度