港珠澳大桥沉管隧道合拢口水动力条件数值模拟研究

The Hong Kong-Zhuhai-Macao Bridge submarine tunnel was constructed by the immersed pipe. Before the final joint is installed, a closure gap will be formed in the middle of the immersed pipe. The water flow is often concentrated in the closure cap with a fast increasing velocity, which adds difficulty to the installation of the final joint. In this article, a three-dimensional mathematical model of water flow in the local waters of the closure gap was established, and the flow structure in the closure gap area was simulated. The relationship between the closure gap water flow and the Pearl River runoff including the tidal range was analyzed. The simulation results showed that the surface velocity in the closure gap was greater than the bottom one, and the velocity of ebb tide was greater than that of flood tide. The closure gap water flow increased with the increase of the tidal range under the same runoff, and the closure gap water flow increased with the increase of the upstream runoff under the same tidal range. The crane ship used in the final joint installation were only 30 m away from the closure gap. The bowing action of the bow made the flow rate of the local waters on the west side of closure gap increase sharply, but it had less influence on closure gap water flow conditions. According to the numerical simulation results of the hydrodynamic conditions in the closure gap, the external water conditions and the appropriate time for the final joint installation and construction were determined, which provided technical support for the final completion of the Hong Kong-Zhuhai-Macao Bridge immersed tunnel.