强震区隧道软弱围岩洞口段桩-筏抗震措施的作用效果分析

为进一步提高地震时软弱围岩铁路隧道安全性及稳定性，以玉磨铁路新平隧道工程作为依托，利用FLAC3D数值模拟软件，对强震区隧道软弱围岩洞口段桩-筏抗震措施效果进行研究，对比分析了无加固措施、措施一（桩-拱结构）及措施二(桩-筏-拱结构)二衬的结构位移及内力，研究结果表明:措施一和措施二的竖向位移分别减小了1.35%、1.09%；措施一的边墙收敛几无变化（增大了0.44%）；由于桩-筏-拱结构的整体稳定性较好，措施二的边墙收敛减小了30.49%；距离洞口最近的两个危险截面1和2处，措施一的最小安全系数提高了1.43%、6.71%，措施二的最小安全系数提高了145.91%、143.72%；综合位移及内力分析，措施二的抗震效果优于措施一，建议新平隧道洞口段采用桩-筏-拱结构进行抗震加固。

Analysis on the effect of pile-raft anti-seismic measures for the tunnel section of weak surrounding rock in strong earthquake area

In order to further improve the safety and stability of railway tunnels with weak surrounding rocks during earthquake, the Xinping tunnel at Yumo Railway was taken as an example and, to study the effect of pile-raft seismic measures at the tunnel opening in soft surrounding rocks during strong earthquake using FLAC3D numerical simulation software. The structural displacement and internal force of the two linings without reinforcement were compared, the research results show that the vertical displacement of the pile-arch structure reduced 1.35% and that of the pile-raft-arch structure reduced 1.09%; the side wall convergence of the pile-arch structure has little change (increase 0.44%); due to the better overall stability of the pile-raft-arch structure, the side wall convergence of it is reduced by 30.49%; At the two dangerous sections closest to the entrance of the tunnel, the minimum safety factor of the pile-arch structure has been increased by 1.43% and 6.71%, and the minimum safety factor of the pile-raft-arch structure has been increased by 145.91% and 143.72%; The anti-seismic effect of the pile-raft-arch structure is better than that of the pile-arch structure. It is recommended that the pile-raft-arch structure should better be adopted for seismic reinforcement at the opening section of Xinping tunnel.