以温福铁路琯头岭隧道下穿同三高速公路隧道为例，研究新建下穿隧道与既有隧道工程之间相互影响的问题。采用ANSYS有限元软件，模拟上覆公路隧道和下穿铁路隧道的位移和应力变化情况，并与现场监控量测结果对比，得到以下结果： 下穿隧道拱顶沉降量较小，水平收敛值较大，下穿隧道立交段拱腰和边墙是需要重点支护的对象； 上覆隧道在立交段下沉值变大，变化幅度为仰拱>边墙>拱腰>拱顶，隧道中部和下部水平收敛值变化较大； 受下穿隧道开挖影响，立交隧道上覆地层受力产生不均匀变化，造成扭矩存在，地面水平位移整体呈现“8”字形，立交隧道的建设对地层产生了较大的转动扰动。

The interaction between newlybuilt Guantouling Tunnel on WenzhouFuzhou Railway and existing Tongsan Highway Tunnels is studied. The displacement and stress of upper tunnel and lower tunnel are simulated by software ANSYS, and the analytical results are compared with monitoring data. Some conclusions are drawn as follows: 1) The crown top settlement of undercrossing tunnel is small and the horizontal convergence of it is large, the arch waists and sidewalls are weak points should be supported at overlapped section. 2) The settlement of upper tunnel at overlapped section is large; the settlement of inverted arch is the largest, followed by those of sidewalls, arch waists and crown top; the horizontal convergence of tunnel at middle and lower part varies much. 3) The homogeneous variation of stress of covered strata would be induced by construction of underneath crossing tunnel, as a result, torque would be induced.