椭圆变形模式下隧道非线性地基反力确定及其数值模拟OA

Explicit nonlinear formulations for the subgrade reaction(pr)of circular tunnels under oval deformation remain scarce.In this paper,a hyperbolic expression for pr is developed based on the mobilizable strength design(MSD)method and the elastic displacement solution for oval deformation,incorporating parameters from the unified hardening(UH)model.A validation framework is further established based on the effective stress principle,with consideration of pore pressure evolution.First,a finite element model of a semi-infinite soil domain employing the modified cam-clay(MCC)and UH constitutive models is constructed to examine the applicability of the elastic displacement solution under oval deformation and to evaluate the predictive accuracy of the proposed hyperbolic model.Subsequently,a refined three-dimensional load-structure model incorporating the pr formulation is established using a total stress approach with coupled soil-water analysis.Comparative verification against a soil-structure model that accounts for pore pressure evolution reveals that,under conditions without ground loss and with low to moderate surcharge,the tunnel convergence predicted by the load-structure model agrees well with that of the soil-structure model.However,the current pr formulation does not account for the plastic deformation mechanisms induced by pore pressure dissipation,which becomes particularly significant under short-term high surcharge conditions.This paper provides a more comprehensive validation approach for theoretical subgrade reaction formulations that incorporate soil stress-level dependent effects,offering clearer guidance for the rational application of the underlying theoretical assumptions.