港珠澳大桥人工岛对水沙动力环境的影响

为了评估港珠澳大桥人工岛建设对周边海区水沙动力环境的影响,针对人工岛设计及工程海区水沙特性,建立了整体潮流泥沙物理模型,系统研究了人工岛建设引起的动力地貌演变效应。试验结果表明,受岛体阻水影响,潮流在人工岛两端分别形成双向绕流,流速明显增大,并在岛桥结合部与岛隧结合部发育局部冲刷坑;人工岛背水面同时存在多个大小不一的强紊动小尺度回流,并具有不断形成、发育、发展到消亡的周期性变化过程。受人工岛自身位置、形态、尺度以及工程海区地形、水流、泥沙等因素影响,港珠澳大桥东、西两个人工岛引起的动力地貌演变效应,既在变化规律上具有较好的一致性,又在影响形式与程度上存在明显的差异性。

Effects on the hydrodynamics and sediment environment by artificial islands of the Hong Kong-Zhuhai-Macao Bridge

In order to predict the effects on the hydrodynamic and sediment environment caused by the artificial islands of the Hong Kong-Zhuhai-Macao Bridge, the physical model for the bridge is built to analyze the changes of the tidal level, tidal current and seabed evolution caused by the artificial islands. The physical model is based on the characteristics of the flows and sediment transportation in the project sea area. The experimental results show that the drag force on flow is increased and the flow section area is decreased by the two large artificial islands built in the sea. Near each end of the artificial islands, the velocities of tidal currents increase and the local scour holes form. At the downstream side of the artificial islands, there is the recirculation zone with many vortexes in different scales, which have a periodic change from formation to disappearance. Affected by the topography, hydrodynamic and sediment conditions in the project sea area, as well as by the position, shape and scale of the artificial islands, the changes of hydrodynamics and sediment environment by both the west and east artificial islands are similar in the change rules and different in the forms.