模型几何变态对弯道悬移质泥沙冲淤变形影响试验研究

Experimental Study on Effects of Model Geometrical Distortion upon Suspended Sediment Scouring and Silting in Bent Reaches

选择变率e=1,2,4,6,8,10的系列弯道概化模型,采用相似的水沙条件进行动床模型试验,根据各变率模型试验成果与正态模型对比,研究模型几何变态对弯道悬移质泥沙运动引起的冲淤变形的影响,并分析其影响因素,为河工模型的试验研究和生产实践提供借鉴。研究结果表明,悬移质泥沙运动相似性与模型变率成反比,与宽深比和弯道曲率半径成正比;当模型变率不大于4、宽深比不小于6.3时,河床变形与正态模型基本相似,反之,则相似性较差;就满足弯曲河道悬移质泥沙冲淤变形相似性而言,模型几何变率不大于4为宜;在同变率条件下,河床变形的偏离程度,弯道段大于顺直段,弯道凸岸模拟采用动凸岸比定凸岸河床变形更为相似。

For studying the effects and factors of model geometrical distortion on similarity of suspended sediment scouring and silting, a series of generalized physical model tests with distorted scale ratio e = 1, 2, 4, 6, 8, 10 were conducted. The results show as follows： The similarity of suspended sediment load transport is inversely proportional to distortion ratio, and proportional to ratio of width to depth and curvature radius for bend reach. When distortion ratio is smaller 4 and the ratio of width to depth is more than 6.3, the model is basically similar in riverbed deformation to the normal model, otherwise, they have bad similarity. To meet the requirement of river physical model similarity, the model geometrical distortion should be less than 4. When the distortion ratio is same, the deviation degree of riverbed deformation in bent reaches is larger than that in straight reaches between distorting model and normal model. Moreover, the similarity of riverbed deformation with mov- able convex bank is better than that with concrete convex bank in bent reaches.