河床冲淤是引起过江隧道纵向变形的一个主要原因。以杭州地铁2号线钱塘江过江隧道为背景，通过数值模拟和理论计算相结合的方法，阐述河床冲淤引起过江隧道纵向变形的机理，研究通过横断面计算方法导出隧道纵向变形曲线，论证隧道环间连接刚度与纵向变形的关系，并提出了控制纵向变形问题的建议。

One of the main reasons for the longitudinal deformation of rivercrossing tunnels is riverbed scouring and siltation. Taking the construction of Qiantang River Crossing Tunnel on No.2 line of Hangzhou Metro as an example, the authors present the mechanisms of the longitudinal deformation of rivercrossing tunnels caused by riverbed scouring and siltation by means of numerical simulation and theoretical calculation. Furthermore, they educe the longitudinal deformation curve of the tunnel by means of crosssection calculation, demonstrate the relation between the connection stiffness of the lining segments and the longitudinal deformation of the tunnel, and finally make some advice to control the  longitudinal deformation of the tunnel.