糙率减小与洪峰增值关系的数值模拟研究  

Study on numerical simulation of relationship between roughness decrease and flood peak increase

作　　者：张小峰[1] 元媛[1] 赵梓涵[1,2] 

机构地区：[1]武汉大学水资源与水电工程科学国家重点实验室,湖北武汉430072 [2]山东黄河勘测设计研究院,山东济南250013

出　　处：《泥沙研究》2014年第6期36-43,共8页Journal of Sediment Research

基　　金：国家自然科学基金项目(51379155)

摘　　要：以矩形断面河槽为研究对象,采用一维非恒定水流数学模型,模拟计算了糙率变化对下游洪峰增值过程的影响。结果表明:在河床断面不发生冲淤,断面形状沿程不变,且只考虑清水的情况下,当糙率不变时,随着洪水逐渐向下游传播,受河道槽蓄作用的影响,洪峰流量沿程逐渐衰减,峰型趋于矮胖;当糙率随时间减小且上游变化率大于下游河道时,发生流量沿程异常增大的现象,且变化率越大,增值越明显。通过理想情况下的单因素分析,认为糙率随时间沿程减小时,下游洪峰会发生增值现象。此外,进口洪峰形态对洪水演进有一定的影响。峰型越矮胖,下游断面的洪峰流量增幅越大;当入口为连续洪峰时,因两峰叠加,洪峰异常增值有所加剧。Influence of roughness change on downstream flood peak increase is studied by one-dimensional un- steady flow mathematical model, and river channel with rectangular cross-sections is employed in this paper. The flow is assumed as clear water, there is no bed scouring and siltation in river channel, and the shapes of cross-sections keep unchangeable along the channel. Based on the research results, under the circumstance of constant roughness, the flood peak discharge attenuates and peak pattern grows chunky along the river because of the influence of the channel storage and side wall resistance. In the case that roughness decreases with time and reduction rate of upper reaches is greater than that of the lower reaches, the discharge increases abnormal- ly along the river channel. In addition, the greater is the reduction rate, the more obvious is the peak increase. Through the single factor analysis in ideal conditions, it shows that downstream flood peak increase will occur if roughness decreases along river channel. In addition, the shape of inlet flood peak has an effect on flood routing. The chunkier is the peak pattern, the larger is the extent of flood peak increase. When the flood enters the calculation region with two consecutive flood peaks, the peak increase will be further aggravated because of the superposition of two flood peaks.

关 键 词：洪峰增值 糙率变化 洪水演进 数值模拟 

分 类 号：TV143[水利工程—水力学及河流动力学]