Influence of hydro-mechanical coupling on tunnel response in clays

The design of deep tunnels underneath the water-table in clayey soils should carefully take into account the influence of pore pressures and seepage forces on the stability of the excavation and on the loading conditions of the support systems. The paper focuses on the application of analytical solutions and numerical models for the analysis of stress and deformation around deep tunnels, in the short- and long-term, considering the idealized situation of axisymmetric conditions. General remarks on the influence of hydro-mechanical coupling, artificial boundary conditions and lining permeability are presented. Theoretical predictions are compared with measurements made in tunnels excavated in the Boom clay formation at Mol (Belgium).