Hydraulic response to a shaft excavation in Callovo-Oxfordian clay

Abstract

This document presents a coupled hydro-mechanical (HM) numerical analysis,using Code_Bright, simulating the excavation of the main access shaft to the underground laboratory of Bure (France) in Callovo-Oxfordian Clay. The work consists in the description of the HM formulation using a specially developed constitutive law and in the discussion of the simulation results. The mechanisms at the origin of the water pressure response are analysed with special emphasis on the influence of the mechanical and hydraulic boundary conditions used for the shaft excavation. Shaft convergence and permeability evolution measured by ANDRA (Modex-REP mine-by-test, [1,2]) during the shaft excavation are compared with the modelling results to illustrate the model capability to reproduce excavation induced damage and to relate it to permeability increase.