Modélisation numérique de l'apport du renforcement par boulonnage du front de taille des tunnels

Abstract

We have first developed empirically the technique of reinforcement of the cutting face of tunnels, which allows for the excavation of full sections in layers of hardened soils or soft rock. Although numerous studies of numerical simulations have been proposed so far, the three-dimensional (3D) simulation of reinforcement of the cutting face of tunnels remains a heavy and costly procedure in terms of preparation and calculation, due in particular to the geometrical complexity and the different scale levels involved. Hence, it appears necessary to have at our disposal, especially at the pilot study stage, some simplified models that allow for a quick evaluation of the efficiency of the reinforcement. The bibliographical survey of the actual practices has led us to consider two methods: the first one consists of considering the effect of inclusions as equivalent to a pressure applied to the front, and the second one consists of a reinforcement of the cohesion ahead of the front along the length of the reinforcement. These two approaches have been compared to 3D calculations to evaluate their relevance.Key words: soil-structure interaction, tunnels, deformation, reinforced soils, numerical modelling, analysis.