Abstract：Xiamen East Passage subsea tunnel is the first subsea tunnel in China；and its geological conditions are complex and unfavorable with enriched groundwater. During the tunnel construction，the deformation of tunnel support is great. It is important to seek for a reasonable countermeasure to restrict the large deformation to ensure safety construction. Focused on Xiamen East Passage subsea tunnel，field monitoring data are analyzed and numerical calculation is employed. Some measures against abnormal deformation，including setting locking anchor bar，enhancing stiffness and intensity of temporary support，grouting in inverted arch，constructing continuous wall for groundwater proof，changing construction method，are taken. Finally，the countermeasure for abnormal deformation is offered. The analytical results indicate that，to some extent，each countermeasure can decrease the displacements of the tunnel support and all these countermeasures will also reduce plastic area in surrounding rock and increase structure safety to a certain extent. For example，after setting locking anchor bars，arch crown settlement will be reduced about 17%；and level convergence will be reduced 12% and after grouting in inverted arch；arch crown settlement will be reduced about 18%. The analytical method and result can provide references to the latter construction of Xiamen subsea tunnel and the other similar engineering cases.
