【作者】 夏文颖；

【导师】 杨胜发；

【作者基本信息】 重庆交通大学 ， 港口、航道及近海工程， 2010， 硕士

【摘要】 泥沙起动是河流动力学及河床演变学中的基础性问题,国内外许多学者对此进行了研究。到目前为止,所提出的无粘性颗粒的起动公式已有100个左右,但能反映天然河流的卵石起动,特别是非均匀卵石起动的公式鲜见。所以开展对非均匀卵石起动规律的研究,具有重要的理论意义和工程适用价值。本文分析了泥沙起动公式的三种表达形式。通过对床面泥沙颗粒的受力分析,采用对数流速分布分析得到起动拖曳力公式;采用指数流速分布得到起动流速公式;从功率角度出发得到起动功率公式,得知水流功率与粒径的3/2次方成正比。天然河流大多属于非均匀流,但起动拖曳力公式和起动流速公式都是在均匀流的基础上建立起来的。因此,本次研究采用起动功率公式分析卵石与非均匀卵石的起动规律。首先,通过高精度水槽试验,并收集大比降卵石试验资料,对均匀卵石试验数据进行分析,得到卵石起动功率无量纲数为: W_c^* = VHJ/（gD³）^1/2)=0.16。其次,通过整理寸滩站和朱沱站的大量非均匀卵石起动数据,考虑床面的粗化,在床面最大粒径基本相同的情况下,河床组成越粗,所需起动功率也越大。因此,在均匀卵石起动功率公式中引入反映粗化程度的参数Db 50 / Dbmax,得出非均匀卵石起动功率公式。最后,结合均匀与非均匀卵石起动数据,得出反映非均匀流、非均匀卵石特性的起动功率无量纲数为: W_c^* = 0.16×(D_b50/D_bmax¹.05.更多还原

【Abstract】 Incipient motion is a basic problem about river dynamics and sediment movement, there are many domestic and foreign scholars have studied it. So far, the proposed non-cohesive sediment formulas have been more than 100, but it is very less formula which reflected gravel motion particularly non-uniform gravel in natural rivers. So it has theoretical and engineering application value to research the gravel motion of mountain river follow as the analysis of the power of the gravel particles.The paper studied several forms of sediment formula. By analyzing the stress on the sediment particles, and using logarithmic velocity distribution, obtained the starting formula of drag force; using exponential velocity distribution to get the starting velocity formula; obtaining the power formula from a power perspective, we have known that it is proportional between water power and size of 3 / 2 Th. Most of the natural river flows are non-uniform, but the start and the starting velocity drag force formula for formulas are based on uniform flow up. Therefore, this paper used the formula of starting power to study uniform gravel and non-uniform motion laws.Firstly, by a large drop test and high-precision flume test, analyzing the data of the uniform gravel, obtaining the gravel motion power formula is: W_c = VHJ/（gD³）^1/2 =0.16.Secondly, by ordering a large number of non-uniform gravel starting data at Cuntan and zhutuo station, considering the coarsening of the bed, it is thought that the coarser of the composition of river bed, the greater start power required in the case of the same maximum size in bed. Therefore, it is introduced a parameter D_b50/D_bmax which reflect the degree of coarse based on the uniform gravel motion formula to get the non-uniform gravel motion formula.Finally, combining with uniform and non-uniform gravel motion data, obtaining starting power formula ( W_c = 0.16×(D_b50/D_bmax¹.05（gD³）^1/2) which reflect the non-uniform flow and characteristics of non-uniform gravel.更多还原