依托连霍高速公路扩建工程通过郑西高铁阌乡隧道上方这一典型案例，采用FLAC3D有限差分程序对施工过程进行三维仿真分析。从横断面、纵剖面的变形两个方面对高速铁路隧道安全状态进行了研究。从纵剖面来看，仰拱位移普遍小于拱顶位移，且受地形和隧道与开挖区域的相对位置影响，最大位移发生在50 m位置处的拱顶，量值为6.3 mm，每10 m的最大差异沉降为0.97 mm，小于高速铁路轨道变形要求；从横断面来看，隧道结构由于上部开挖导致卸荷效应，整体呈现隆起趋势，其位移方向趋向于开挖区域。现场施工和监测表明通过采用竖向分层、纵向分段的开挖方式，阌乡隧道的结构变形量得到有效控制，保证了扩建工程的施工安全与高速铁路隧道的运营安全。

The upgrade project of LianHuo expressway crosses over Wenxiang tunnel on ZhengzhouXi’an highspeed railway. In the paper, 3D simulation analysis is made on the construction process of the expressway upgrade by means of FLAC 3D finite difference program. The safety state of the highspeed railway tunnel is studied in terms of displacement in both crosssection and longitudinal profile. Conclusions drawn are as follows: 1) In the longitudinal profile, the displacement  of the invert is less than that of the crown, the displacement is influenced by both the topography and by the relationship between the tunnel and the expressway upgrade excavation area, the maximum displacement (6.3mm) occurs at the crown at Station 50m, and the maximum differential settlement in every 10m section is 0.97mm, which is smaller than the limit value of the highspeed railway tracks; 2) In the crosssection, due to the unloading effect caused by the overlying expressway upgrade excavation, the tunnel structure has a uplift tendency toward the excavation area; 3) The  upgrade construction practice and the monitoring data show that, due to the layerbylayer excavation in vertical direction and sectionbysection excavation in longitudinal direction adopted, the structural deformation of Wenxiang tunnel  has been brought under effective control, and the construction safety of the expressway upgrade works and the operation safety of the highspeed railway tunnel have been guaranteed. 