Comportement des tunnels pressurisés en milieu urbain

Nowadays, the use of pressurized tunnel boring machines in urban areas has en-abled the possibility of limiting soil deformations due to tunnel constructions. However, due to the heterogeneous nature of the soils and the ap-plication of inappropriate pressures by the tun-nel boring machine, irreversible scenarios (damage to the surrounding area) can occur. In order to avoid this, it appears essential to predict the ground displacements due to tunnel construction.Analytical, empirical and numerical methods have been developed for the prediction of tunnel-induced settlement. Among these methods, numerical ones have proven their effectiveness with the three-dimensional (3D) approach. However, this approach has a major drawback which is its cost in computation time. To overcome this problem, the two-dimensional (2D) ap-proach, which is a simplification of the three-dimensional approach, is often adopted. However, this approach requires the transformation of the pressures applied by the TBM into a fictitious pressure to be applied with the 2D ap-proach. Concerning the consideration of soil heterogeneity in the numerical prediction, this latter requires a large number of 2D simulations and consequently a high cost in terms of calculation time, which limits the use of this expensive ap-proach. In this thesis, a numerical simulation methodology (two- and three-dimensional) with finite elements capable of predicting the response of soils to tunneling with a TBM by taking into account the heterogeneity of soils was proposed. To achieve this, a formulation allowing simplifying the pressures of the TBM into a 2D ficti-tious pressure has also been proposed in order to respect a defined settlement threshold and thus ensure the stability of the nearby structures. According to this formulation, the fictitious pressure is mainly related to the pressure around the shield and the grouting pressure to fill the gap between the mortar and the excavated soil.During the construction of the tunnels, measurements of soil deformations are compared with the predictions and very often there is a discrepancy between the two settlement troughs. This phenomenon was observed on the extension of the Paris metro Line 12 where the tunnel was excavated in a stratified soil layer. This thesis also proposes a back-analysis methodology to find the adequate set of parameters with which it is possible to obtain the numerical settlement trough closest to the measurements.Subsequently, a sensitivity analysis applied to the extension of the Parisian metro Line 12 was also conducted, which allowed studying the influence of the soil layers on the settlement trough.Other 3D and 2D numerical simulations allowed to understand the influence of the excavation phenomenon on the soil response (settlement, stress evolution and strain evolu-tion). A methodology that takes into account the heterogeneous nature of the soil was also proposed in order to study the influence of this character on the displacement of the soil and on the damage to the structures located in the vicinity of the tunnel. Finally, metamodels have been developed using a coupling between neural networks and clustering algorithms (k-means) on the one hand and the multi-fidelity approach on the other hand to predict the surface settlement trough and the level of damage to nearby buildings.