淹没透水丁坝周围三维水沙运动及致损机理研究

This project aims to solve the key technical problems in the constructions of the typical river hydraulic structures - spur dikes. With the combined method of flume experiment and numerical simulation, The study of three-dimensional fluid-sediment motion around the submerged permeable spur dike and its damage mechanism under is conducted. The physical models of permeable spur dikes will be built in the form of grid slab and block stone, while the dynamics parameters of flow and sediment around these spur dikes will be measured in detail by using three-dimensional PIV-V3V system. A three-dimensional numerical model which is available to simulate the interaction between flow, sediment and permeable structure is built. After the verification by experimental data, the numerical model is applied to conduct extensive simulations. By analyzing flow field, vortex pattern, turbulence intensity, suspended load concentration, bedload transport rate and bed variation obtained from the flume experiment as well as numerical simulation, the three-dimensional characteristics of flow and sediment motion around the permeable spur dikes as well as their interaction mechanism under steady flow conditions and submergence variation conditions are revealed. The scientific descriptions on the damage mechanism is established accordingly, which can provide theoretical basis and technical support for the design, construction, maintenance and reinforcement of permeable spur dikes in engineering applications.

本项目针对典型河流水工结构物丁坝建设中亟待解决的关键技术问题，采用明渠水槽试验和数值模拟相结合的方法，开展淹没透水丁坝周围三维水沙运动及致损机理的研究。拟以栅格直板和块石堆砌为主要结构物形式建立透水丁坝水槽试验模型，借助PIV-V3V系统建立三维水沙粒子图像量测方法，对丁坝周围的水沙动力学参数进行详细的测量与分析。同时构建描述水流、泥沙与透水丁坝相互作用的三维湍流数值模型，采用水槽模型试验结果验证其有效性并进行扩展数值研究。通过深入分析水槽试验和数值模拟中透水丁坝周围的流速场、涡旋形态、湍动强度、悬移质泥沙浓度、推移质输沙率和底床变形等参数，从微观物理层面上揭示在恒定淹没状态下或淹没条件转化过程中，丁坝周围的三维水沙运动特性及相互作用机理，建立坝体致损机理的科学描述，为真实河流中透水丁坝的设计施工和维护加固提供基础理论依据和技术支撑。

本项目针对河流水工结构物透水丁坝周围三维水沙运动及坝体致损机理的关键工程技术问题，开展了明渠水槽试验和数值仿真模拟的研究。利用三维PIV系统对处于未淹没、刚淹没和完全淹没三种状态下坝体周围的绕流流场和底床冲刷时空变化形态开展了多角度的测量，通过分析最大冲坑深度和空间位置的关系，对坝体损毁规律特性进行了系统的归纳和总结；同时建立起能够准确描述水流、泥沙与透水丁坝相互作用的三维湍流数值模型，在引用水槽试验数据对数值模型进行详细验证的基础上，开展了大量的扩展数值试验工况，对坝体周围的流速场、涡旋形态、湍动强度、悬移质泥沙浓度和底床变形等水沙动力学参数进行详细的分析与研究，揭示了水流强度分布、湍动变化规律和冲坑演化形式等重要的工程参考指标，提炼总结出透水丁坝周围三维水沙运动特性及其相互作用机理；在此基础上，将建立的数值模型应用于长江纳溪航道杨柳碛河段的双丁坝实际工程中，在进一步验证模型的基础上，对真实河流问题中丰枯水期转化下的三维水沙运动特性进行模拟，并与现场观测数据进行对比分析，为实际工程的设计施工和维护加固提供基础理论依据和技术支撑。