The effect of the anisotropic state of stress on the normal force in a deep tunnel preliminary deformable lining

When deep tunnels are excavated in poor ground, squeezing conditions occur and the design of supports must follow the yielding principle. To this aim, special elasto-plastic elements embedded in the temporary support can be employed. The presence of the elastic-plastic elements radically modifies the ground-lining interaction mechanisms making necessary the use of numerical analyses. Particularlyrelevant is the case of anisotropic geostatic state ofstress. The paper reportsand discusses, someresults from2D numerical ground-lininginteraction of deformable temporary support with initial non-isotropic stress field.Results of the classic rigid support are also reported and compared.