局部液化地层范围及埋深对隧道地震上浮的影响研究

Study on the Influence of the Local Liquefaction Formation Range and Burial Depth on the Seismic Floating Displacement of Tunnel

杭州地铁4号线甬江路站—锦江站区间施工时需穿越大范围的可液化地层,为降低隧道在地震作用下上浮破坏的潜在风险,该区间选线时将隧道埋深进行了增大,从而使隧道部分处于非液化土层。为了研究在地震作用下盾构隧道局部液化地层范围以及隧道埋深对隧道上浮的影响,并对隧道调整后的抗震效果做出评价,采用有限差分软件FLAC^(3D)数值模拟与振动台试验相结合的方法,对处于不同液化土层分布范围、不同埋深的隧道地震上浮情况进行了数值分析及模型试验,研究结果表明:隧道液化地层范围越小,隧道上浮位移越小;当隧道埋深达14 m、隧道液化地层范围小于隧道范围一半时,隧道只发生轻微上浮;隧道设计时应尽量避免使隧道完全处于可液化地层中,可采取液化与非液化地层组合或增大埋深的方式,提高隧道结构的抗震安全性。

During the construction of the section from Yongjiang Road Station to Jinjiang Station of Hangzhou Metro Line 4,a wide range of liquidiable strata should be traversed.In order to reduce the potential risk of the tunnel destruction which could be caused by tunnel floating when earthquake acts,the buried depth of the tunnel was increased,so that part of the tunnel was located in the non-liquified soil layer.In order to study the influence of the local liquefaction formation range and burial depth on the seismic floating displacement of tunnel,and to evaluate the earthquake-resistance effect of the tunnel after adjustment,the finite difference software FLAC 3D numerical simulation and shaking table test were combined to carry out numerical analysis and model tests on the seismic uplift of tunnels in different liquefied soil layers and different buried depths.The results are as follows:the smaller the range of liquefied stratum is,the smaller the floating displacement is.When the tunnel is buried to 14 meters deep and the liquefaction ground layer of the tunnel is less than half of the tunnel area,the tunnel only slightly floats;Tunnels should avoid being completely in liquidiable formations,the seismic safety of the tunnel structure can be improved by combining the liquefied and non-liquefied stratum or increasing the buried depth.