The work presented in this manuscript aims at studying the behaviour of shallow tunnels excavated with pressurized shields, by investigating two fundamental points : the stability of the tunnel face with respect to collapse and blow-out, and the occurrence of soil movements at the ground surface. The study first deals with deterministic aspects, and then focuses on a probabilistic approach. In a first time, several analytical models for the determination of the collapse and blow-out limit pressures are developed from observations of numerical results. Two of these models, respectively for frictional and purely cohesive soils, appear to provide very satisfying results, both for the computation of the limit pressures and for the assessment of the failure shape. Moreover, two numerical models of increasing complexity are programmed in order to evaluate the soil movements induced by the excavation, and their propagation to the ground surface. These deterministic models are then used in a probabilistic framework. The Collocation-based Stochastic Response Surface Methodology is presented, validated, and generalized in order to make possible at a limited computational cost a complete parametric study on the probabilistic properties of the input variables. The uncertainty propagation through the models of stability and ground movements is evaluated, and some methods of reliability-based design are proposed. In a last part of the manuscript, the spatial variability of the soil is taken into account using the random fields theory, and applied to a 2D analytical model of tunnel face collapse. This model, developed in order to take into account this variability for much smaller computation times than numerical models, is validated numerically and submitted to extensive random samplings. The effect of the spatial variability is evaluated, a emerging phenomena related to this variability are pointed out.
