弯道推移质泥沙运动特性及其对河道演变的影响

弯曲河道水流、泥沙的运动特性与顺直段不同,存在横向流速与横向输沙。在考虑了弯道河段横向水流影响的条件下,导出了弯道河段泥沙的起动流速公式,并进行了合理性分析,认为在相同的纵向流速条件下,弯道段凹岸侧泥沙的起动粒径和泥沙输移速率均较顺直段大。同时结合弯道段水流和泥沙的运动特性阐明了弯道河段的演变规律。

Motion characteristics of bed load sediment in river bend and their effects on fluvial evolution

Motion characteristics of water flow and sediment in bend reach are different fr om that in straight stream by ocurring transverse velocities and transverse sedi ment transportation.Considering the effects of transverse flow in river bend,a f ormula for starting velocity of sediment in river bend is derived and rational a nalysis performed.It is regarded that,under the condition of same longitudinal v elocities,the values of particle size of the started particles and their transpo rting speed on the concave bank are all larger than those in straight river sec tion.In the meanwhile,the evolution regularity of bend river is represented in combination with the motion chara-cteristics of water flow and sediment in bend reaches.