截流戗堤单向进占的局部冲刷三维数值模拟  

Three-dimensional numerical simulation of the flow characteristics and local scour around closure dike with one-way closing

作　　者：李登松 戴光清[2] 金鑫 漆力健 唐巍 LI Deng-song;DAI Guang-qing;JIN Xing;QI Li-jian;TANG Wei(College of Water Conservancy and Hydropower Engineering,Sichuan Agricultural University,Ya'an 625014,China;State Key Lab.of Hydraulics and Mountain River Eng.,Chengdu 610065,China;Chengdu University of Technology,Chengdu 610059,China)

机构地区：[1]四川农业大学水利水电学院,雅安625014 [2]四川大学水力学与山区河流开发保护国家重点实验室,成都610065 [3]成都理工大学能源学院,成都610059

出　　处：《水动力学研究与进展（A辑）》2020年第4期444-453,共10页Chinese Journal of Hydrodynamics

摘　　要：戗堤截流主要在河道截流和堤坝溃口封堵等水利和防洪减灾工程中得到应用,戗堤周围的水力冲刷直接影响工程的安全性。由于戗堤进占过程表现出较强的三维非恒定性,因此目前采用三维数值模型全面细致地模拟进占过程中戗堤周围的三维水流结构和冲刷特性较少。该文基于有限体积法和非结构化的计算网格构建了以水动力学模型、泥沙冲淤和河床变形方程为基础的三维局部冲刷数值模型,从室内明渠截流工程实验中得到的龙口平均流速、上下游水位落差、底床切应力分布与地形变化的关系等结果验证了数值模型的可靠性。利用该数值模型模拟了截流戗堤单向进占方式下不同进占长度时戗堤附近和龙口处的三维水流特性,以及戗堤周围局部冲刷地形的发展。通过分析水流特性与冲刷坑发展的关系,阐述了戗堤周围局部冲刷的物理成因。研究结果表明:涡旋和下潜水流是戗堤附近河床剧烈淘刷的主要原因;单向进占时戗堤对水流具有偏移效应;在初始阶段,冲刷趋势表现为沿堤头的上游至裹头下游形成的斜向轴线冲刷;在冲刷发展过程中,龙口中部出现泥沙淤积,主要冲刷区位于戗堤和裹头绕流后的底床。研究成果进一步表明数值仿真技术可应用于工程截流实践中,能预测截流中可能出现严重堤脚淘刷的位置与趋势。The closure dike is mainly used in water conservancy and flood prevention and disaster reduction projects such as river closure and block of dam break flow. However the scour around the dike are going to affect the safety of the project. The flow shows strongly three-dimensional unsteady characteristics during the dike length changes. The three-dimensional numerical simulation is seldom used to comprehensive and detailed simulate the flow and local scour around the dike. Therefore, a three-dimensional numerical model of local scour based on a hydrodynamic model, sediment erosion and deposition equation, and riverbed deformation equation was constructed in this study. The reliability of the numerical model was verified by the experimental results such as the average velocity, the shear stress and the topographic change of riverbed. The numerical model was used to simulate the three-dimensional flow and local scour topography around the dike. The results show that the flow is deflected to the other side. The vortices and downward submersible flow are the main reasons for severe scour of the river bed. The scour trend is manifested as the oblique axis scour formed along the upstream of the dike head to the downstream of the wrapping head. In the process of erosion developing, sediment deposition occurs in the axis of the gap, and the main erosion areas are located at the bed of the dike head and wrapping head.The research results further show that the numerical simulation can be applied to river closure engineering.

关 键 词：戗堤截流 单向进占 水流特性 局部冲刷 三维数值模拟 

分 类 号：TV135.2[水利工程—水力学及河流动力学]