为研究覆有厚层松散堆积体且穿越软硬交界面的隧道洞口段动力响应特点和抗减震措施，以飞仙关隧道洞口段为研究对象，采用有限差分软件分别建立隧道围岩渐进式注浆、设置减震缝和全环注浆3种工况，并和无措施情况下隧道衬砌的应力、变形对比，得出最佳抗减震措施。研究结果表明： 1）在强震作用下衬砌的纵向变形远远小于横向变形，且全环注浆对限制衬砌的横向变形效果最显著，单独设置减震缝对衬砌变形的限制效果较差； 2）隧道右拱脚和右拱腰是强震作用下结构破坏的最危险位置，需着重加强这2处的抗震加固； 3）全环注浆能够有效减小衬砌应力，同时还能使交界面附近应力变化连续而平稳。

The portal section of Feixianguan Tunnel is taken for an example to study the dynamic response characteristics and seismic resistance/reduction measures of tunnel portal section covered by thick loose deposits and crossing softhard interface. Three conditions are established by finite difference software, including progressive grouting measures, fullring grouting measures and setting shock absorption joints. By comparing stress and deformation of tunnel lining under the condition of no measures, the optimum seismic resistance/reduction measures are obtained. The results show that: (1) The longitudinal deformation of lining is far less than transverse deformation under strong earthquake, and the effect of fullring grouting on limiting the lateral deformation of lining is the most significant, while setting shock absorption joints separately tends to be poor effective. (2) The right arch foot and the right arch waist are the most dangerous locations for structural damage under strong earthquake, thus emphasis should be laid on strengthening the seismic reinforcement at these two locations. (3) Fullring grouting can effectively reduce lining stress, and it can make the stress change near the interface continuous and stable meanwhile.