Finite element analysis of the Meuse Haute-Marne underground research laboratory

International audienceThe Meuse/Haute-Marne Underground Research Laboratory (ANDRA) has been excavated to study the feasibility of a deep underground repository in the Callovo-Oxfordian argillite. The laboratory, lying at depth between 420 m and 550 m, has a complex structure due to the shape and location of various shafts and drifts. The purpose of this study is to analyse the mechanical behaviour of rock due to the excavation process, and the mechanical interaction between drifts and shafts during the excavation steps. Numerical analysis, which considers the geometry and excavation sequence of the Underground Research Laboratory (URL), is carried out using a finite element model having 2.5 million degrees of freedom with relatively simple constitutive equations describing the argillite's behaviour. The main interest of such large-scale modelling is to analyse the evolution of various mechanical fields during excavation progress. Indeed, comparisons between 2D and 3D analysis are performed and show that the 2D-plane strains assumption is no longer fulfilled in some areas of the laboratory. The results of the analysis are used to highlight areas where interaction between drifts and/or shafts is important. It is helpful to restrict the field of the analyses using some relevant criterion or appropriate boundary conditions, to perform the numerical simulations based on a more realistic elasto-visco-plastic constitutive model for rocks