清水冲刷下均匀天然沙含沙量恢复过程试验研究  

Experimental Study on the Uniform Natural Sand Recovery Process by Unsaturated Flow

作　　者：郭小虎[1] 于倩[2] 渠庚[1] 陈栋[1] 朱勇辉[1] 

机构地区：[1]长江科学院水利部江湖治理与防洪重点实验室,湖北武汉430010 [2]华北水利水电大学水利学院,河南郑州450045

出　　处：《应用基础与工程科学学报》2017年第3期427-441,共15页Journal of Basic Science and Engineering

基　　金：国家自然科学基金项目(51409017;51339001;51309022);水利部公益性行业科研专项(201401011);科技部重点研发专项(2016YFC0402303;2016YFC0402305);三峡后续规划研究课题三(CKSG2016874/HL)

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.Sediment concentrations would not be saturation after the construction of the reservoir, causing long distance erosion;These will bring a series of problems, such as flood control, water resource utilization and shipping, because of scouring process complexity, the sediment concentration recovery is one of the difficult problems in the river sediment dynamics. In this paper, based on the turbulent burst theory, the theoretical formula of the recovery about the sediment concentration is derived, by use of experiments in the equipped with advanced apparatus such as Type-B Ultrasonic Sediment Instrument, the recovery process of suspended sediment under different conditions is clarified. When the flow and bed slope are constant, the bed slope are 0.5%o.1.0%~ and 2. 0%0, and small differences are shown in the process of the sediment concentration recovery, al （ The ratio of near bottom and vertical average sediment concentration） is a process that is gradually close to oq （The ratio of near bottom and vertical average Sediment carrying capacity） during the scouring process;When the bed size and bed slope are constant, the greater the flow, the greater the distance of the sediment concentration recovery, also the larger al ,a2 value ; When the flow, bed slope bed are constant, the finer the particle size, the greater the value and distance of the sediment concentration recovery, and vice versa.

关 键 词：清水冲刷 含沙量恢复 恢复饱和系数 

分 类 号：TV147[水利工程—水力学及河流动力学]