邕宁水利枢纽一期临时土石围堰数值模拟研究

Numerical Simulation of the 1st Stage Temporary Earth-Rock Cofferdam of Yongning Water Conservancy Project

南宁市邕宁水利枢纽工程位于邕江干流,一期临时土石围堰施工是保证右岸一期全年土石围堰工程施工的关键重点工程。为了解决临时土石围堰的合龙位置、束窄河床通航等问题,采用三维数值模拟和物理模型试验方法对其施工期水流进行了深入研究。首先,用CATIA建立了河道地形和围堰三维几何模型,基于RNGκ-ε紊流模型及TruVOF追踪水流自由表面的方法,用FLOW3D计算了设计挡水流量下围堰中间合龙和围堰挡水典型工况的水流特性,并与物理模型试验成果进行了对比,验证了计算方案的正确性;其次,计算了设计挡水流量下靠上游合龙、靠下游合龙其他工况的水流特性,并进行了综合比较,提出了最佳合龙位置为纵向围堰中部;第三,选取四种流量进行了水流特性计算,分析了束窄河床关键通航水力学指标,结果表明,在一期临时土石围堰挡水期内满足通航要求。

The Yongning water conservancy project of Nanning city is located in the main stream of Yongjiang river.The construction of temporary earth-rock cofferdam is a key project to ensure the construction of the 1 st year-round earth-rock cofferdam on the right bank.In order to solve issues such as closure position of the temporary earth-rock cofferdam and the navigation of narrowed river bed,3-D numerical simulation and model test method were used to study the flow characteristics during construction.Firstly,3-D geometric model of the river topography and cofferdam was established by CATIA,based on RNGκ-εturbulence model and TruVOF method for tracing free surface of flow,flow characteristics for typical cases of closure in the middle position and cofferdam water retaining were calculated by FLOW3 D under designed flow rate and the correctness of the calculation scheme was verified comparing with the results of model test.Secondly,flow characteristics for other cases such as closure in the upstream and downstream position are calculated,and comprehensive comparison results showed that the optimal closure position is in the middle part of the longitudinal cofferdam.Thirdly,4 kinds of flow rate including 3010 m3/s,2480 m3/s,1730 m3/s and 1230 m3/s were selected to calculate the flow characteristics,key navigation hydraulic indexes of the narrowed river bed were analyzed,and the results showed that the navigation requirements can be met in the period of retaining water of the 1 st temporary earth-rock cofferdam.