长江近河口段河型规律与桥位选择

Research on selection of bridge position and river patterns at the near-estuary reach of the Yangtze River

桥区河势河床稳定性分析及河型研究在桥梁工程及港址选择等诸多涉水工程中均具有重要意义。研究表明洪水是长江近河口段分汊河型交替摆动演变和塑造河床地形的框架动力;实践表明按河型规律因势利导的人工工程对分汊河型稳定性可发挥有效的控制作用,此为长江近河口段桥位布选、主跨布设及建桥后稳定性河势维护的指导思路。本文通过对长江下游分汊河型的动态分类和特点研究表明,以分汊河型间的节点段和主泓稳定的江心洲分汊河型具有较高的稳定性,主泓交替摆动的江心洲分汊河型次之,而心滩分汊河型为较不稳定的分汊河型,这是长江近河口段建桥桥位布选的判断依据。

Analysis of stability of river regime and riverbed in the bridge area as well as river patterns is of great significance in the construction of bridges and the selection of harbour-site.Research shows that floods are the dominant force to the swinging evolution of bifurcated river pattern and riverbed topography at the near-estuary reach of the Yangtze River.Practices show that artificial works in accordance with the law of river patterns play an important role in the stability of bifurcated rivers.The above is the directive thoughts for the selection of bridge position,layout of main span and maintenance of stable river regime after the construction of bridges at the near-estuary reach of the Yangtze River.Research shows that the nodal reaches of bifurcated river and the bifurcated river with stable central shoal are of higher stability,and the bifurcated river with alternative central shoal is less stable.It is the basis for selection and layout of bridge position at the near-estuary reach of the Yangtze River.