来沙条件变化对河床形态及推移质运动的影响

摘要：针对山区河流的来沙条件的不确定性导致的河流形态变化的问题，根据J . G. Venditti的系列来沙条件变化水槽试验成果，引入无量纲参数河床结构强度Sp,充分考虑推移质泥沙运动特性，探讨了来沙条件变化对卵石河床形态、推移质输沙率和河床级配的影响。结果表明:在已经粗化的河床上加入细沙会对河床形态、推移质输沙率和河床级配产生影响。加入细沙会造成河床重新出现冲淤变化，底坡变大，冲刷变严重，最终降低河床结构强度Sp；加沙会增大推移质输沙率，其中中值粒径为3mm的细沙运动表现为行进推移质，而中值粒径为8mm的粗沙运动表现为结构推移质；加入细沙后会细化河床，且加入的粒径越小，细化效果越明显，加入中值粒径为3mm的细沙后推移质的中值粒径先减小后增大，与加入中值粒径为8mm的粗沙后推移质的中值粒径先增大后减小相反。

Study on effects of incoming sediment change on river bed-form and bed load transport

Abstract: In order to solve the problem of mountain river to river morphology with the changes of uncertainly sediment supply conditions, based on J. G. Venditti series of flume experiments in sediment supply, coinciding fully the characteristics of bed load sediment movement, a parameter Sp was introduced to describe the intensity of a riverbed form. Study on effects of incoming sediment change on river bed-form , bed load transport and sediment gradation. Results showed that, adding sand to the river bed of the river will affect the bed morphology, bed-load transport rate and channel grading in an armor layer. Sediment supply will caused river bottom again appeared rushed silt changes, eventually variable increase the slope , variable serious the scour and eventually reduce the intensity of the river bed structure Sp; Sediment supply will increase the bed-load transport rate, and sediment supply grain diameter sand for 3 mm of sediment for travelling bed load , and in the value grain diameter for 8 mm of sediment for structure bed load; Sediment supply will refinement river, which grain diameter smaller effect than grain diameter larger of particles effect obviously.After joining the median particle size of 3mm sand over mass median particle size decreases and then increases and median particle size of coarse 8mm insteadly.