寒区输水工程絮状冰花型冰塞形成机理和防治研究

Due to the low temperature in winter, water transfer project in cold region will inevitably face the problem of water supply during winter and generate corresponding safety hazards. With the increase of water supply year by year, the risk of ice damage of the Middle Route of the South-to-North Water Transfer Project is prominent, and it shows that the ice jam danger is different from the natural river ice phenomenon and characterized by flocculent -like ice jam. Due to the obvious difference between the formation mechanism and the hydraulic characteristics in water transfer project and natural river, the existing natural river ice hydrodynamic theory cannot be directly applied to the water transfer project and is difficult to be effective to solve the running problems and security risks in winter..Based on the special ice conditions of the flocculent-like ice jam in water transfer project, this study uses a combination of theoretical analysis, physical model testing, and numerical simulation. Starting from the transport and evolution of flocculent ice in water transfer projects, reveal its formation mechanism and characteristics, and thus establish a 1D-3D coupled numerical simulation method of flocculent ice jam in water conveyance project. Propose the prevention methods and measures for the flocculent ice jam in the water transfer project, covering “Prevention-control-emergency”. It provides a theoretical basis for the safe and stable operation of water transfer project in cold region, and provides guarantee for maximizing the water transport capacity of the South-North Water Transfer Middle Route project during winter.

寒区输水工程受冬季低气温影响，不可避免的都会面对冰期输水问题，并产生相应的安全隐患。南水北调中线工程运行至今，伴随输水量增长，冰害风险凸显，并呈现出区别于天然河流冰情现象，以絮状冰花型冰塞为特点的冰塞险情。由于人工输水工程与天然河流中的冰情问题无论在形成机理还是在水力特性方面存在明显差异，现有的天然河道冰水动力学理论既不能直接应用于寒区输水工程中更难以有效解决其中的运行问题与安全隐患。.本研究针对寒区输水工程絮状冰花型冰塞的特殊冰情，采用理论分析、物理模型试验和数值模拟相结合的方法，从絮状冰花在输水工程中的输移和演变规律入手，揭示其形成机制和特征，由此建立一维-三维耦合的输水工程絮状冰花型冰塞数值模拟方法，提出针对寒区输水工程絮状冰花型冰塞，涵盖“预防-控制-应急”的全链条式防治方法和措施，进而为寒区输水工程冰期安全稳定运行提供理论依据，为南水北调中线工程冰期输水能力最大化提供保障。

对于高纬度或者高海拔地区的输水工程，在冬季输水过程中将不可避免的遇到冰害问题。寒区输水工程中常易发生的冰塞与天然河道中的冰塞在形成机理、特性以及防治等方面存在明显差异，主要表现为絮状冰花的大量堆积形成的冰塞或冰坝危害。由于输水工程的线性串联特征，局部渠段或闸前的冰塞问题，不仅会给所在渠段带来工程破坏和损失，更会严重削弱整个工程的冬季输水能力，进而直接威胁沿线城市的冬季供水。.本项目针对输水工程中絮状冰花导致的输水能力显著降低问题，展开絮状冰花型冰塞形成机理和防治研究。首先，絮状冰花形成机理层面，基于冰晶碰撞理论，引入了临界碰撞速度和絮凝概率，得到了计算冰晶数量的通用公式，并进一步建立了水内冰概率演化模型；在机理研究的基础上，基于新的水内冰生消演变模型构建了水力-水温-水内冰耦合预测模型，系统研究了冬季输水水温演化特征，结合控制变量法分析了不同气象条件、水力条件下的水温、冰情演化过程，得到了南水北调中线工程冬季输水不冻长度和无冰害长度的计算公式，并提出相应的水力调控建议和阈值控制建议。最后，基于理论研究成果，研发了利用太阳能的保温增温廊道装置、增温单元装置，和利用地热能的地下水库增温技术，并对不同保温增温技术措施的控温效果、运行控制方式等展开深入分析，以点-线结合的方式为冬季输水水流补充热能，降低水内冰含量，为絮状冰花型冰塞的防治提供理论和技术依据。研究成果具有较强的落地性和可操作性，有效解决了冬季输水所面临的输水能力瓶颈问题，进一步提升了冬季供水保证率，为保障工程沿线城市的冬季生产、生活用水提供重要支持。