渠冰生消机理对西部寒旱地区输水工程的破坏性研究

In the west cold and arid regions, icing phenomena in different degrees are common during the water delivery in the water conveyance project in winter. Different kinds of ice damages in water conveyance facilities are the major factors affecting the safety of water conveyance projects. These ice damages form in 3 different processes which are the freezing period, freeze-up period and frost-free period. In the conveyance projects, the canal ice formation is closely associated with the frazil ice evolution. Therefore, it bears both theoretical and practical significance to reveal the relationships among frazil ice, canal ice and water conveyance project, and to discover the failure law of the canal ice on the water conveyance project. Based on the background of conveyance projects in the west cold and dry regions and the researches of home and abroad, the subject intends to adopt the methods of field test, theoretical study, numerical simulation and indoor model experiments on different working conditions to research the forming method and dissipation mechanism of canal ice. It also plans to consider the effect of thermal expansion pressure of canal ice on the open canals. The model test method would be adopted to discuss the impact force and squeeze pressure of different quality ice and different flow rates on the water conveyance projects during the canal ice melting. The subject is aimed at solving the water delivery stability and security problems during freezing period in the western water conveyance projects, and further proposing the water delivery measures and control methods according to the climate features of winter in west China.

西部寒旱地区的输水工程在冬季输水时，普遍存在着不同程度的结冰现象。输水设施在结冰期、封冻期和解冻期三个过程中形成的不同种类冰害是影响输水工程安全性能的主要因素。而输水工程中渠冰的形成与水内冰演变密切相关，揭示水内冰、渠冰和输水工程之间的关系，发现渠冰对输水工程的破坏规律，对西部寒旱地区输水工程冬季安全运行具有重要的理论与现实意义。本课题以西部寒旱地区输水工程为研究背景，在国内外研究基础上，通过现场试验、理论研究、数值模拟及室内模型，选取不同工况，研究渠冰的形成方式与生消机理；研究渠冰温度膨胀力对明渠的影响；通过模型试验对渠冰消融时不同流速和不同质量冰体对输水工程的挤压力和撞击力进行了研究。通过研究水内冰、渠冰和输水工程之间的关系，揭示渠冰对输水工程的破坏规律，目的是解决西部输水工程在冰期安全、稳定输水的相关问题，提出适合西部地区冬季气候特点的输水措施和控制方法。

本课题针对西部寒旱地区的输水工程在冬季输水时，普遍存在着不同程度的结冰现象。以西部寒旱地区输水工程为研究背景，在国内外研究基础上，通过现场试验、理论研究、数值模拟及室内模型，选取不同工况，研究渠冰的形成方式与生消机理；通过模型试验对渠冰消融时不同流速和不同质量冰体对输水工程的挤压力和撞击力进行了研究。.本课题研究流冰与明渠相互作用的碰撞模拟问题，利用接触-碰撞算法的有限元中对称罚函数算法，进行了流冰撞击的接触-碰撞算法的有限元实现。以引大入秦输水枢纽为例，分析明渠的破坏机理。应用ANSYS软件建立明渠模型和流冰模型，发现了不同流速、不同冰排平面尺寸、不同冰排厚度下流冰对明渠撞击力的影响。建立流冰撞击明渠实验装置进行试验；模拟了明渠中流冰碰撞的全演变过程，分析了流速、流冰尺寸、流冰厚度等不同工况下流冰对明渠和隧洞的撞击力规律，通过试验模型验证了数值模拟的基本吻合性。揭示渠冰对输水工程的破坏规律，目的是解决西部输水工程在冰期安全、稳定输水的相关问题，提出适合西部地区冬季气候特点的输水措施和控制方法。研究结果说明数值模拟和实验结果基本吻合。项目的研究将对寒旱地区输水工程设计、施工及运营维护提供科学依据和技术支撑，丰富冰水力学基础科学研究内涵。