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张治国, 陈金芃, 朱正国, PANY T, 孙苗苗. 波流耦合影响下分层海床隧道周围砂土渗流孔压及液化分析[J]. 岩土工程学报, 2024, 46(4): 683-693. DOI: 10.11779/CJGE20230008
引用本文: 张治国, 陈金芃, 朱正国, PANY T, 孙苗苗. 波流耦合影响下分层海床隧道周围砂土渗流孔压及液化分析[J]. 岩土工程学报, 2024, 46(4): 683-693. DOI: 10.11779/CJGE20230008
ZHANG Zhiguo, CHEN Jinpeng, ZHU Zhengguo, PAN Y T, SUN Miaomiao. Sand liquefaction and seepage pore pressure around shield tunnels in multilayered seabed under action of waves and currents[J]. Chinese Journal of Geotechnical Engineering, 2024, 46(4): 683-693. DOI: 10.11779/CJGE20230008
Citation: ZHANG Zhiguo, CHEN Jinpeng, ZHU Zhengguo, PAN Y T, SUN Miaomiao. Sand liquefaction and seepage pore pressure around shield tunnels in multilayered seabed under action of waves and currents[J]. Chinese Journal of Geotechnical Engineering, 2024, 46(4): 683-693. DOI: 10.11779/CJGE20230008

波流耦合影响下分层海床隧道周围砂土渗流孔压及液化分析

Sand liquefaction and seepage pore pressure around shield tunnels in multilayered seabed under action of waves and currents

  • 摘要: 目前针对波浪作用下海底盾构隧道周围渗流场的既有理论研究一般将衬砌考虑为不透水介质,较少考虑隧道衬砌的渗透性,尤其是较少考虑波浪与海流共同作用对隧道的影响。此外,既有理论一般将海床视为均质且各向同性工况,忽略了实际情况下分层海床的影响。首先,基于波流共同作用下的海床表面的动力边界条件,采用传递-反射矩阵法得到波流共同作用下自由分层海床的孔压响应;其次,采用镜像法建立了由于隧道存在引起的砂土摄动压力控制方程,并利用砂土与衬砌间渗流连续条件获得了该方程的Fourier级数展开解析解;接着,采用叠加原理得到了波流共同作用下分层海床中隧道周围砂土的渗流压力响应及液化判定解答。最后,将理论解析解与数值结果及已有的试验结果进行对比,获得了较好的一致性。此外,针对海床渗透性和隧道衬砌渗透性进行了影响因素分析。结果表明:海流顺流会增大海床中的孔压和液化程度,逆流会减小海床中的孔压并抑制海床的液化,且流速相同时海床对逆流响应的相对差异总体上也大于顺流;当分层海床上层渗透系数较大时(ks>1×10-2 m/s),海床整体孔压较大,且第一次分层处孔压变化明显;当隧道衬砌渗透系数较小时(kl<1×10-6 m/s),隧道对超静孔隙水压在海床内传播“阻挡”效应明显。

     

    Abstract: At present, the existing theoretical studies on the seepage field around subsea shield tunnels under wave action generally consider the linings as an impermeable medium, and seldom consider the permeability of the tunnel linings, especially the influences of the coupling action of waves and currents on the tunnel. In addition, the existing theories generally regard the seabed as being homogeneous and isotropic, ignoring the influences of multilayered seabed. Firstly, based on the dynamic boundary conditions of seabed surface under wave-current interaction, the pore water pressure response of pure seabed under wave-current interaction is obtained by the transmission and reflection matrix method. Secondly, the mirror image method is introduced to establish the governing equation for the excess pore water pressure caused by the existence of tunnel, and the analytical solution of the equation is obtained by the Fourier series expansion under the continuous seepage between sand and linings. Then, based on the superposition principle, the seepage pressure of the sand around the tunnel in multilayered seabed under the action of waves and currents is obtained. Finally, the theoretical analytical solution is compared with the numerical results and the existing experimental results, and a good agreement is obtained. In addition, the influencing factors for the permeabilites of seabed and tunnel linings are analyzed. The results show that the following currents will increase the pore pressure in the seabed and the liquefaction degree of the seabed, while the opposing currents will reduce the pore pressure in the seabed and the liquefaction of the seabed. The relative difference of the seabed response to the opposing currents at the same velocity is generally greater than that of the following currents. When the permeability coefficient of the upper seabed is large (ks > 1×10-2 m/s), the overall pore pressure of the seabed is large, and the pore pressure at the first stratification changes significantly. When the permeability coefficient of tunnel linings is small (kl < 1×10-6 m/s), the tunnel has an obvious "block" effects on the propagation of the excess pore pressure in the seabed.

     

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