镫口扬水灌区骨干渠道淤积特性和影响因素研究

发布时间：2018-05-15 04:43

本文选题：淤积特性 + 入渠特性　；参考：《内蒙古农业大学》2014年硕士论文

【摘要】：引黄渠道的泥沙淤积问题是当今水工程界极为关注并致力于研究解决的重要问题。本文以内蒙古镫口引黄扬水灌区总干渠为研究对象，分别对2012年和2013年四个灌水期泵站开、停泵时取水口前的泥沙淤积厚度以及运行期间抽水流量、入渠含沙量及渠道各断面含沙量进行了观测，根据观测数据，依据水力学和泥沙理论，对取水口及总干渠的泥沙淤积问题进行了分析研究。研究内容主要包括取水口泥沙淤积特性和入渠特性、总干渠泥沙的输移与淤积、沉降与悬移特性，含沙量变化规律及其与各影响因素间的关系等。研究结果表明：（1）取水口淤积情况取决于取水流量、取水口的分流宽度、泵站停泵时间等。取水流量越大，取水口分流宽度越大，泵站停泵时间越短，，取水口前淤积厚度越小；取水口的淤积厚度分布呈现上游大于下游的趋势，即取水主流区偏向下游，流速比η越大，这种趋势越明显。（2）影响黄河泥沙入渠的主要因素包括开泵时取水口前的淤积状况、流速比η以及取水口分流宽度等。开泵时取水口前淤积厚度越大，流速比η越小，取水口分流宽度越大，推移质入渠量越大。取水口前设置拦沙坎可有效阻止推移质入渠。（3）水流速度、悬移流速及起动流速之间存在三种关系，相应渠道处于冲刷、淤积和不冲不淤状态。含沙量的变化规律呈现沿程降低、沿程增加、变化平缓和起伏较大四种状态。渠道含沙量S与各影响因素的相关性由强到弱分别为流速/U、悬移质沉速/、床沙中值粒径/D50床、水深/h和悬移质中值粒径/D50悬。其中S与U、、D50悬呈幂函数关系，与h呈线性函数关系，与D50床呈指数函数关系。（4）悬移质挟沙能力占总挟沙能力的比重较大，推移质挟沙能力占总挟沙能力的比重较小。影响悬移质（推移质）挟沙能力的粒径不仅是悬移质（推移质）粒径，还与床沙粒径有关。悬移质和床沙粒径均较小时，悬移质和推移质挟沙能力均较大。（5）利用Van Rijn公式进行渠道挟沙能力的计算，与实测结果相关性较好。故本文采用该方法进行挟沙能力和淤积量计算。
[Abstract]:The siltation of the Yellow River diversion channel is an important problem which the water engineering field pays close attention to and devotes to solve. In this paper, taking the main trunk canal in Inner Mongolia's stirrup mouth as the research object, the silt deposition thickness of the four pumping stations in 2012 and 2013 before the opening and stopping of the pump intake and the pumping flow during the operation are respectively studied. The sediment content in the channel and the sediment concentration in each section of the canal were observed. According to the observed data, the siltation problem of the intake and the main canal was analyzed and studied according to the hydraulic and sediment theory. The main contents of the study include the characteristics of sediment siltation and the characteristics of entering the canal, the transport and deposition of sediment in the main channel, the characteristics of sedimentation and suspension, the variation law of sediment content and the relationship between sediment content and the influencing factors, etc. The results show that: The siltation of the intake depends on the water flow, the width of the diversion, the pump stop time and so on. The larger the intake flow, the larger the diversion width, the shorter the pump stop time, the smaller the deposition thickness before the intake, the larger the distribution of sediment thickness is upstream than the downstream, that is, the lower the flow velocity is, the lower the velocity is. The more obvious this trend is. 2) the main factors affecting the silt flow into the channel of the Yellow River include the siltation condition before the intake, the velocity ratio 畏 and the diversion width of the intake when the pump is opened. When the pump is opened, the bigger the deposition thickness is, the smaller the velocity ratio 畏 is, the wider the diversion width is, and the larger the bed load is. The sand bar before the intake can effectively prevent the bed load from entering the canal. 3) there are three relationships among flow velocity, suspended velocity and starting velocity, and the corresponding channel is in the state of scouring, siltation and no scouring and no silting. The change rule of sediment content shows four states: decrease along course, increase along course, change slowly and fluctuate greatly. The correlation between the sediment content S and the influencing factors from strong to weak is velocity / U, suspended sediment sedimentation velocity, bed sediment median particle diameter / D _ (50) bed, water depth / h and suspended sediment mean particle diameter / D _ (50) suspension respectively. Among them, the relationship between S and UD50 is a power function, a linear relationship with h, and an exponential function with a D50 bed. (4) the proportion of suspended sediment carrying capacity to total sediment carrying capacity is larger, and the proportion of bed load sediment carrying capacity to total sediment carrying capacity is relatively small. The particle size which affects the sediment carrying capacity of suspended sediment is not only the particle size of suspended sediment, but also the particle size of bed sediment. The particle size of suspended sediment and bed sediment are both small, and the carrying capacity of suspended sediment and bed load is larger. 5) the calculation of sediment carrying capacity by Van Rijn formula has a good correlation with the measured results. Therefore, the method is used to calculate the sediment carrying capacity and silting capacity.
【学位授予单位】：内蒙古农业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV146

【参考文献】