Apports de la simulation numérique tridimensionnelle dans les études de tunnels

Abstract

Contributions of the three-dimensional numerical simulation in tunnels studies. The excavation of underground structures and, in particular, tunnels is a complex three-dimensional problem, wherein the ground reaction depends on various factors such as the nature and characteristics of the soil, the geometry of the work and the excavation method adopted. In an urban context, the construction of these works poses the problem of interaction with surface buildings and existing underground structures. The current practice of tunnels projects design, particularly concerning ground deformations, is mainly based on the twodimensional analysis, in a cross-section with in-plane deformations combined with the convergence–confinement method. However, this method, wherein the validity of the results is based on the correct choice of the stress release coefficient l, is often used in situations where the basic assumptions are not respected. This article provides some examples showing how 3D modeling has become an indispensable tool today, for geotechnical design engineers, to study certain issues in all their complexity and to better approximate the reality. Studies presented deal with works carried out in traditional and mechanized method, where the prediction of settlements and interactions with existing structures is a priority project issue.