清水冲刷下均匀天然沙含沙量恢复过程试验研究

发布时间：2018-06-05 13:55

  本文选题：清水冲刷 + 含沙量恢复　； 参考：《应用基础与工程科学学报》2017年03期

【摘要】：水库修建后,清水下泄将造成坝下游河道处于冲刷状态,引起河势调整,给下游防洪、水资源利用及航运等可能带来一系列不利的影响;由于坝下游清水冲刷过程的复杂性,沙质河床含沙量沿程恢复规律一直是河流泥沙动力学的难度问题之一.基于此,首先本文根据湍流猝发理论推导出清水冲刷下沙质型河床含沙量沿程恢复的理论公式,然后利用配置精密仪器的变坡水槽试验进行相关研究,并根据试验数据分析不同条件下垂线平均含沙量沿程恢复的特性.试验成果显示,当流量、床沙粒径不变,河床比降为0.5‰、1.0‰与2.0‰时,垂线平均含沙量恢复过程差异性较小,但随着冲刷距离发展α_1(近底处含沙量与垂线平均含沙量比值)递减而α_2(近底处挟沙能力/垂线平均挟沙能力比值)略有增加,且在清水冲刷发展过程中α_1是一个逐渐靠近α_2的动态变化过程;当床沙粒径与河床比降不变,流量越大,水流垂线平均含沙量恢复饱和的数值与距离越大,α_1、α_2数值同样也越大;当流量、河床比降不变,床沙粒径颗粒越细,含沙量恢复饱和时的数值越大,恢复距离也越长,反之亦然.
[Abstract]:After the reservoir is built, the discharge of clear water will cause the downstream channel of the dam to be scoured, causing river regime adjustment, which may bring a series of adverse effects to the downstream flood control, utilization of water resources and navigation, etc. Due to the complexity of the process of water scouring downstream of the dam, The recovery rule of sediment content along sandy river bed is always one of the difficult problems in river sediment dynamics. Based on this, the theoretical formula of sediment content recovery of sandy riverbed under clear water scour is deduced according to the turbulent burst theory, and then the correlation research is carried out by using the experiment of variable slope flume with precision instrument. According to the experimental data, the characteristics of the average sediment content along the vertical line are analyzed under different conditions. The experimental results show that the difference of the average sediment content recovery process of the vertical line is small when the flow rate and the bed sediment diameter are constant, and the river bed ratio is reduced to 0.5 鈥，

本文编号：1982215