Analytical Solution for Surface Consolidation Settlements Induced by Shield Tunneling with Semi-permeable Boundary Conditions Under Train Loading in Viscous Field

The long-term leakage of tunnel lining under the action of train loading can significantly change the consolidation settlements of soft soils around the shield tunnel, which may adversely affect the surrounding environment and safe operation of the subway. Currently, the impermeable condition of the lining is usually used to analyze the consolidation settlements of soils around a shield tunnel. However, the coupled influences of lining leakage and train loading on the consolidation settlements have been rarely considered. Using the semi-permeable boundary of tunnel lining and the triangle cyclic time-dependent loading of the train, considering the Terzaghi-Rendulic consolidation theory, the Boltzmann viscoelastic model was employed to simulate the rheological characteristics of the soils; the conformal mapping in complex variable theory was used to derive the dissipation solution of excess pore water pressure and the surface consolidation settlement under train loading in viscoelastic soils. Furthermore, the analytical solutions were verified using observation data from six project cases. Finally, a detailed sensitivity analysis was performed between the influence of the soil-lining permeability and the train loading on the surface consolidation settlement. In this study, the accuracy and applicability of the analytical solution were verified based on the comparison of the measured data of the six projects. The results showed that the lining-to-soil permeability ratio was the primary factor affecting the rate of consolidation of the soils; the greater the lining-to-soil permeability ratio, the sooner the consolidation is completed. Upon applying the train loading, the consolidation settlement rate increases significantly compared with that without the train loading. However, further increase in the train loading does not increase the consolidation settlement rate significantly. This increment is closely related to the lining-to-soil permeability ratio; the larger the lining-to-soil permeability ratio, the larger the consolidation settlement. The tunnel lining can be regarded as the drainage boundary of disturbed stratum; it accelerates the consolidation settlement of soils. While the train load and lining semi-permeability are coupled, they further change the style of consolidation settlement of soils. © 2022, Editorial Department of China Journal of Highway and Transport. All right reserved.