Improved Method for Evaluating the Tunnel Response Induced by Adjacent Surcharge

The imposition of surcharge loads adjacent to subsurface structures can precipitate significant alterations in the soil’s mechanical behavior, thereby jeopardizing the structural safety of nearby tunnels. In response to this challenge, an analytical solution has been developed to quantify the interaction between a tunnel and its surrounding soil under the influence of surcharge loads. Initially, the Boussinesq equation is employed to calculate the additional stresses imposed on an existing tunnel by adjacent surcharges. Subsequently, the system’s energy equation is formulated by integrating the dual-parameter Vlasov foundation model with considerations of the lateral soil impact on the tunnel. This solution facilitates the computation of the tunnel’s total energy using variational energy principles, leading to an analytical solution for the tunnel-soil interaction. Validation of this method against empirical data from Shanghai confirms its accuracy. A parametric analysis indicates that increasing the horizontal distance between the tunnel and the surcharge load progressively reduces both the tunnel’s settlement and bending moments. Additionally, augmented surcharge loads and tunnel diameters are associated with a nonlinear escalation in tunnel settlement and internal forces.