Adjacent to the surcharge load, the settlement deformation of the soil below will further threaten the safety of the existing tunnel. Based on this condition, firstly, the Boussinesq formula was used to obtain the additional stress of the existing tunnel under the influence of the adjacent surcharge load. Then, the energy equation of the existing tunnel system under the influence of the adjacent surcharge load was established by using the two-parameter Vlasov foundation theory and effect of the lateral soil of the tunnel. Then, the total energy of the tunnel was solved by the energy variational theory, and the analytical solution of the tunnel-soil interaction was obtained. Compared with the existing measured data, the rationality of the method was verified. The result shows that the increase of tunnel diameter will cause the nonlinear increase of tunnel settlement and internal force. Increasing the buried depth of the tunnel will cause the settlement and bending moment of the tunnel to decrease gradually. Increasing the bending stiffness of the tunnel will cause the settlement of the tunnel to decrease and the internal force to increase.