An analytical model for evaluating the dynamic response of a tunnel embedded in layered foundation soil with different saturations.

This paper proposes an analytical model for evaluating the dynamic response of an underground railway tunnel in layered foundation soil with different saturations. The soil is modeled as layered media, and the circular tunnel lining is modeled as an infinite Flügge cylindrical shell. The separation of variables method is used to solve the motion equation of the shell, and the wave equation of the soil is solved using the Helmholtz decomposition theorem. A dynamic matrix reflecting the wave vectors of soil layers is established using the transfer matrix method. Based on boundary conditions, the tunnel-soil model is coupled using the transformation method of plane wave functions and cylindrical wave functions. The proposed model is validated by comparison with existing tunnel models, and the effects of saturation and the layered properties of soil on the dynamic response of a layered tunnel-soil system is demonstrated via case studies. [ABSTRACT FROM AUTHOR]