复式断面河道冰水耦合机理及准二维冰情过程模拟

Natural river usually has compound cross section with main channel and floodplain. At present, ice-hydrodynamics study focuses on simple trapezoid, circular arc or generalized rectangular wide-shallow river sections which cannot reflect boundary conditions, hydraulics conditions and ice accumulation processes in the compound channel correctly. By means of mechanism research of model ice experiment, mathematical model development and field observation verification, flow characteristics and ice-water coupling mechanism in the compound channel will be fully understood. Based on upper research results, a quasi two dimensional ice-hydrodynamics mathematical model also will be developed to satisfy ice regime situation with long freeze-up distance and large time span in north China. .Innovation points: .1. Based on four typical compound sections, flow characteristics of open flow and ice covered flow will be studied systematically. And ice-hydrodynamics characteristics in the compound channel can be fully understood which will overcome shortcomings of existing research..2. A quasi two dimensional ice-hydrodynamics mathematical model will be developed to satisfy ice regime situation in north China, and then verified by field observation.

天然河道常为带有主槽和滩地的复式断面，而目前的冰水动力学研究基本以简单梯形、圆弧形或者概化为矩形浅宽的河道断面作为研究对象，并不能真实地反映复式断面条件下河道边界条件、水力学条件、冰块的堆积演变过程等，从而造成误差。项目采用模型冰机理研究、数学模型研发和原型观测验证相结合，通过精细研究冰盖下的复式断面水流流动特性及其对冰情过程的影响，明确冰水耦合作用机理，在此基础上提出复式断面平面准二维冰水动力学数学模型，以适应我国北方河流封冻距离长、时间跨度大的冰情现状，提高冰情预报数学模型的预报速度和精度。.项目的创新点如下：.一是对4种典型的复式断面形状，开展明流和冰盖下流动特性的系统研究，得到复式断面冰水相互作用特点和耦合机制，弥补现有研究中存在的不足。.二是研究适合于我国北方河流冰情现状的复式断面平面准二维冰水动力学数学模型，并通过原型观测验证。

项目开展了复式断面河道冰水耦合机理相关试验研究，揭示复式明渠冰盖下流速分布同冰盖糙率、流量和水深等水力参数的关系，提出了天然河道的冰盖下流速分布率定和流量计算方法。提出了冰封复式河道的综合糙率通用计算公式。研究了一维非恒定流模型和准二维恒定流模型的耦合，然后在此基础上提出了准二维河冰发展模型。针对单频雷达在冰厚和水深不能同时测量中的不足，提出了冰水情一体化双频雷达测量系统，能够实现冰厚和水深同时、同步的联合测量和精确定位，改变了冰盖下冰厚和水深测量中长期传统落后的技术和手段，大幅度提高冰情观测的效率和精度。研究了倒虹吸等局部水工建筑物的冰塞水力特性和形成机理，建立了明流和平衡冰塞条件下的流速分布、冰塞厚度分布和倒虹吸安全运行水力控制关键判据等。. 项目成果已在黄河中上游、黑龙江上游河段大江大河上成功应用。利用开发的河冰发展模型开展了黄河内蒙古河段的冰情模拟，再现了该河段水温、冰盖厚度增长、冰盖前缘发展、流量和水位变化过程。上述冰情预报结果为主管部门做好防凌预案提供宝贵的时间，取得了显著的经济和社会效益。