水域沉管隧道地震响应的影响因素分析

为分析隧道接头和上覆水对沉管隧道地震响应的影响，采用沉管隧道振动台试验和ADINA有限元软件模拟两种方法进行相关研究. 沉管隧道试验模型材料主要为微粒混凝土，模型缩尺比为1∶30，采用层叠剪切箱装填砂土构成场地，采用黏弹性人工边界和等效荷载输入方法对模型进行仿真分析. 研究结果表明:在同一深度土层，柔性接头沉管隧道的土层加速度放大系数小于刚性接头沉管隧道；当土层发生液化时，其加速度放大系数小于1；当沉管隧道接头剪切刚度（G）减小为0.10G和0.01G时，隧道截面剪应力减小20%和33%，截面轴应力峰值最大值减小16%和30%，截面剪应变峰值分别增加了60%和140%；上覆水使场地加速度放大系数变小，是由于水的存在加大了土层表面的阻尼；在P波作用下，上覆水水深从10 m增长到40 m时，沉管隧道截面剪应力峰值、轴向应力峰值和应变峰值最大值分别以3%～5%、30%～40%和12%～17%的幅度增加. 

Influencing Factors Analysis of Seismic Responses of Water Immersed Tunnel

In order to study the seismic response of immersed tunnels with different joints and under overlying water, large scaled shaking table tests and immersed tunnels seismic response simulations were carried out. The main material of immersed tunnels model was granular concrete. The model scale ratio designed in the tests was 1∶ 30. Laminated shear boxes filled with sand were used in the tests to form the site. The viscous-spring artificial boundary and equivalent load method were adopted in simulation analysis. The results show that acceleration amplification factors of flexible joint immersed tunnels are smaller than rigid joint immersed tunnels in the same layer. The acceleration amplification factor is less than 1 when the soil layer appears liquefied. Under the earthquake, the maximum values of tunnel section shearing stress peak reduce by 20% and 33%, axial stress peak reduce by 16% and 30% and strain peak increase by 60% and 140% when tunnel joint stiffness(G) reduce to 0.10G and 0.01G. Overlying water site makes acceleration amplification factors smaller, because the overlying water makes the site damping increases.Under the vertical earthquake, overlying water increase from 10 m to 40 m, maximum values of tunnel section shearing stress peak, axial stress peak and strain peak increase by 3%?5%, 30%?40% and 12%?17%, respectively.