波浪地震联合作用下砂质海床沉管隧道动力响应分析

Study on Interaction of Sandy Seabed-immersed Tunnel under Combined Action of Earthquake and Wave

对于埋置于海床表层的沉管隧道,波浪作用是不容忽视的常遇海洋环境因素。不同于陆域地下结构,海底沉管隧道地震反应分析和安全评价应考虑波浪的联合作用。基于Biot完全耦合的动力有效应力分析方法,对波浪与地震联合作用下砂质海床-隧道之间的动力相互作用特性进行研究。研究结果表明,相较仅有地震作用,波浪荷载加速了沉管隧道周围海床地震残余超孔压的增长和渐进液化进程,增大了沉管隧道上浮量;波浪与地震联合作用对应的β谱谱值更大,且卓越反应周期向长周期偏移;波浪对海床地震动的影响深度有限,仅对海床地表以下15 m范围内的地震动有放大效应。忽略波浪环境作用对砂质海床场地设计地震动参数的影响,对于沉管隧道抗震设计是偏于不安全的。

For immersed tunnels buried on the surface of the seabed,wave action is a common marine environmental factor that cannot be ignored.Different from the land underground structure,the seismic response analysis and safety evaluation of submarine immersed tunnels should consider the combined action of waves.Based on the Biot fully coupled dynamic effective stress analysis method,the dynamic interaction characteristics between sandy seabed and tunnel under the combined action of wave and earthquake are studied.The results show that the wave load accelerates the growth of the residual excess pore pressure and the progressive liquefaction process of the seabed around the immersed tunnel,and increases the floating amount of the immersed tunnel.Theβspectrum value corresponding to the combined action of earthquake and wave is larger,and the predominant response period shifts to long period.However,the influence of waves on the seabed ground motion is limited in depth and only has amplification effect on the ground motion in the range of 15 m below the seabed surface.Ignoring the influence of wave environment on design ground motion parameters of sandy seabed site may be unsafe for seismic design of immersed tunnels.