港珠澳大桥人工岛水下滩槽演变的数值模拟与工程检验

Engineering effect test and inspection of the evolution of the seabed level near the artificial island of the Hong Kong⁃Zhuhai⁃Macao Bridge

港珠澳大桥地处伶仃洋的湾口水域,东、西人工岛分别位于伶仃洋大濠深槽两侧。人工岛水域水深流急,潮流正面冲击人工岛,易造成人工岛海域水下地形发生大的变化与调整,最终形成以人工岛为中心的局部滩槽新格局。在大桥工程设计阶段,采用伶仃洋二维潮流泥沙数学模型,对人工岛建设后的伶仃洋水沙环境和水下地形冲淤进行了模拟计算。模型预测结果表明,人工岛对伶仃洋水域的水沙环境影响集中在人工岛上、下游各5 km水域内,人工岛呈冲刷趋势,岛体上下游形成以岛为中心的梭状淤积体。人工岛建设10年前后的水下地形冲淤变化结果表明,人工岛建设引起的海床冲淤变化趋势与数学模型预测结果基本一致,此为当初采用的数学模型预测效果提供了良好的佐证。

The Hong Kong⁃Zhuhai⁃Macao Bridge is located at the mouth of Lingdingyang Bay.The east and west artificial islands are on both sides of the Lingdingyang Dahao Deep Channel.The waters of the artificial islands are deep and rapid,and the currents impact the artificial islands frontally,which is likely to cause major changes and adjustments in the underwater topography near the artificial islands,eventually forming a new pattern of the local beach evolution around the artificial islands.In the engineering design stage of the bridge,the Lingdingyang two⁃dimensional tidal current and sediment mathematical model was used to simulate the underwater topography near the artificial island of the Hong Kong⁃Zhuhai⁃Macao Bridge based on the verification of the measured basic data.The simulated results show that the impact of the artificial island on the water and sand environment of the Lingdingyang waters is concentrated in the waters of 5 km upstream and downstream of the artificial island.The results of the erosion and deposition changes of the underwater topography before and after the construction of the artificial island from 2009 to 2019 show that the trend of the seabed erosion and deposition changes caused by the construction of the artificial island is basically consistent with the prediction results of the mathematical model,which provides good evidence for the applicability of the mathematical model.