选沙相似律对模型沙波相似性影响的试验研究

为了弄清选沙相似律对动床模型沙波相似性的影响，开展基于起动相似等3种不同相似律选择模型沙的沙波水槽试验。基于试验观测的沙波波高、波长以及沙波不同部位的水深、流速，对比分析了沙波尺度及其随水流强度变化过程的相似性。结果表明:当模型沙重率、形状与原型沙相同时，满足起动相似的模型沙沙波尺度与原型相似性最高，满足悬浮相似模型沙的沙波整体偏高、偏长，兼顾起动与悬浮相似的模型沙介于两者之间；不同选沙相似律不影响沙波波高、波长随相对水流强度的变化规律，满足不同相似律的模型沙沙波波高均在相同的相对水流强度达到最大值，波长随相对水流强度增大而增大。说明偏离起动相似越少，沙波相似程度越高。

Effect of sediment motion similarity criteria on sand wave similarity

A comparative flume experiment was conducted with a movable-bed model, and a prototype, to elucidate the effect of applying different similarity criteria in model sand selection on the extent of sand wave similarities. The sand wave dimensions (wave length and height) at different water levels, and flow velocities, and their variations in the forms of sand wave produced under different discharge sections, were measured to compare the similarities of the sand wave dimensions with the change of flow intensity between the two. In the test, the sand particle sizes were respectively determined to satisfy separately a sediment incipient motion similarity law, and a sediment suspension similarity law, and then to satisfy them both simultaneously. The results showed that, when the specific gravity and shape of the model were similar to those of the prototype sand wave, the model sand wave that met the similarity of incipient motion criteria was more similar to the prototypical sand wave in terms of sand wave length and height, while the model sand wave that met the similarity of suspension condition had a greater sand wave height and length than the prototype in general. The extent of sand wave similarities for the model sand wave in terms of wave height and length met both of the aforementioned similarity conditions. The different similarity laws used in model sand selection did not affect the changes in the dimensions of the sand wave with increasing relative flow intensities. Although different similarity laws were applied, sand waves in all model tests, and the prototype test, could reach the maximum sand wave height at the same relative flow intensity, while sand wave lengths increased with increasing relative flow intensity. It demonstrated that the smaller the deviation from the sediment incipient motion similarity law, the greater the sand wave similarity between the model and prototype.