杭州湾跨海大桥非通航孔桥跨比选方案的模型试验

Experimental research on the scheme of bridge span in non-navigable openings of the Hangzhou Bay Major Bridge

利用水平比尺与铅直比尺均为100的正态断面模型,研究了杭州湾跨海大桥非通航孔两个桥跨的桥墩对水流的影响。方案一为50m跨径的桥墩方案,在模型中布置了7跨6个桥墩;方案二为70m跨径的桥墩方案,在模型中布置了5跨4个桥墩。在桥位附近的不同距离处还布设了5条断面16个流速测点和4个水位测站,以反映不同桥墩对周围环境的影响,结果表明,两个方案的流速变化率均在9%以内,水位壅高值在0.17m以内。相对而言,方案一对水流影响稍大,但两方案的流速变化率最大差异仅为1.6%,水位变化最大差异为0.03m,与杭州湾跨海大桥整体模型的试验结果基本一致。由于两个方案对水流的影响均在同一量级,且50m跨径的桥墩可以节省巨额投资,又便于施工,因此,建议杭州湾跨海大桥的非通航孔采用50m跨径。

The influence on the flow of the bridge pier, which is situated in non\|navigable opening of the Hangzhou Bay Major Bridge, is analyzed by using the physical model of the cross section, in which both horizontal scale and vertical are 100. Two schemes are compared in the experiment. One is that the bridge span is 50 m and 7 spans are arranged in the model. The other one is that the bridge span is 70 m and 5 spans are arranged. In order to reflect the influence on the flow of the different bridge pier, 16 measuring points of velocity and 4 survey stations of water level are arranged in the model. The experimental result shows that the change rates of the flow velocity are both within 9%, and the change values of water level are both within 017 m. Relatively, the influence of the bridge pier with the 50 m's span is slightly bigger. But the biggest difference of the 2 change rates of the flow velocity is only 16%, and the biggest one of 2 change values of water level is 003 m. So the influence ranges on the flow of 2 kinds of the bridge pier are rather close. This result basically conforms with the conclusion of the physical model for the Hangzhou bay major bridge. Saving huge investment and constructing conveniently, the scheme of non\|navigable opening with 50 m's span is recommended and adopted.