冰封河道综合糙率计算方法比较与分析  

Comparisons of methods for predicting composite roughness in ice-covered rivers

作　　者：陈刚 张玉蓉 浦承松 张天力 顾世祥 CHEN Gang;ZHANG Yurong;PU Chengsong;ZHANG Tianli;GU Shixiang(State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering,Hohai University,Nanjing 210098,China;Yunnan Survey and Design Institute of Water Conservancy and Hydropower,Kunming 650021,China)

机构地区：[1]河海大学水文水资源与水利工程科学国家重点实验室,江苏南京210098 [2]云南省水利水电勘测设计研究院,云南昆明650021

出　　处：《水科学进展》2018年第5期645-654,共10页Advances in Water Science

基　　金：国家水体污染控制与治理科技重大专项(2013ZX07102-006);云南省应用基础研究重点项目(2017FA022)~~

摘　　要：综合糙率是冰封河道水力计算的重要输入参数。根据水流连续性和力的平衡原理,分别推导得到冰封河道综合糙率的通用公式,并选取抛物线形、矩形和梯形作为典型断面,系统地总结Pavlovskiy、Einstein、Lotter、Sabaneev、Larsen、改进的Larsen等常见公式由通用公式基于何种假定(分区的湿周、流速或水力半径相等)简化得到。采用水槽实测数据和野外观测资料,对比上述公式的计算精度,结果表明改进的Larsen公式的计算结果与实测值吻合较好,推荐在工程设计中使用。前5种公式误差较大的原因在于分区的流速、水力半径相等对于冰封河道不具有普适性,尤其是Lotter公式和Pavlovskiy公式在冰盖和河床糙率差异较大时会明显低估冰封河道的综合糙率,在工程设计中应慎重采用。Composite roughness is a vital input parameter for hydraulic calculations of ice-covered channels.Two general equations for deriving composite roughness coefficient in ice-covered streams,based on the principles of flow continuity or force balance,are presented in this paper.Taking parabolic,rectangular,and trapezoidal under-ice flow sections as the representative geometries,this paper systematically summarizes the assumptions（e.g.,equalities of wetter perimeters,subsectional mean velocities,and hydraulic radii） used in the derivation of six formulae：those of Pavlovskiy,Einstein,Lotter,Sabaneev,Larsen and its modified form.Laboratory measurements and field observations were used to examine the performance of those above-mentioned formulae.Comparative results indicated that the modified Larsen formula had the best overall performance and therefore its use is recommended in engineering practice.The first five formulae produced relatively large errors in the prediction of composite roughness of ice-covered streams because the main assumptions of equalities of velocities and hydraulic radii are only valid for few special cases.In particular,care should be taken when using the Lotter and Pavlovskiy formulae because of their underestimation of the composite roughness in high-grade asymmetric channels.

关 键 词：综合糙率 冰盖水流 双层假定 阻力划分 

分 类 号：TV133[水利工程—水力学及河流动力学]