可液化土层隧道围岩的动力响应及液化区发展分析

Analysis of dynamic responses and liquefaction area development of tunnel peripheral rock in saturated liquefiable soil

隧道可液化土层围岩对地震动作用非常敏感,可液化土层动孔压的产生和发展使得地下结构受到上浮作用,从而影响地下结构的稳定性。通过对可液化土层中隧道动力响应计算,研究了不同静应力场隧道围岩动孔压场分布、围岩液化区域分布以及衬砌结构仰拱底与拱顶的动孔压差变化。研究结果表明,不同静应力场对围岩可液化土的动孔压分布、液化区域分布及动孔压差影响较大,其中拱脚和拱肩的变化最显著。随着隧道拱顶沉降位移的增大,隧道围岩孔压场在拱肩和拱脚处呈"X"型向外延伸,液化区域逐渐扩大,最终将隧道周边土体液化区域连成一片;隧道结构周边动孔压差先减小后增大,且动孔压差恒为正值;随着地震动作用,动孔压对隧道衬砌结构的上浮作用持续增大。

Under the strong seismic loading on tunnels and underground structure in saturated liquefiable soil,the soil is sensitive to vibration,and the dynamic pore water pressure increases,so underground structures move up under the vibrating pore water pressure.Finally,underground structures are destroyed seriously.The dynamic responses of tunnels in saturated liquefiable soil are calculated.The dynamic pore water pressure distribution of the tunnel surrounding,and tunnel foundation are studied.The results show that the different static stress fields have great impact on the dynamic pore water pressure distribution of the tunnel surrounding and the tunnel foundation.The change is mainly found at the heel and spandrel of the arch.The dynamic pore water pressure distribution of the tunnel foundation takes the form of X.With the increasing of the tunnel vault settlement,the saturated liquefiable zones of the tunnel surrounding gradually expand,and finally join together.The differential vibrating pore water pressures of the tunnel surrounding are decreased first and then increased with keeping positive values,and also cause the underground structures to move up under the strong seismic loading.