TIME-DEPENDENT EVOLUTION OF THE EXCAVATION DAMAGED ZONE IN THE ARGILLACEOUS TOURNEMIRE SITE (France)
In order to improve Excavation Damaged Zone (EDZ) modelling capabilities, the French Institute of Radioprotection and Nuclear Safety (IRSN) is proposing the case of the Tournemire site within the scope of task C of the DECOVALEX-THMC international project. The main activities of task C include the predictive analysis of the development of the EDZ and its evolution in space and time around three structures excavated in Tournemire argillites. This experimental site enables the assessment of the EDZs around the century-old tunnel, the ten year-old east and west galleries, and the three year-old main gallery. This paper discusses the main experimental results and their interpretation, providing guidance for the EDZ modelling strategy.EDZ fracture analyses from the galleries (cartography) and the radial boreholes (core analyses) allow for accurate structural characterisation of the EDZs. The tunnel has an EDZ with dense, homogeneous fracturing parallel to the wall, resembling onion skins. However, the new galleries do not have an EDZ similar to that of the tunnel. Unsaturated micro-cracks, mainly parallel to the bedding planes are observed on the non covered walls of each gallery. The extent of the EDZ does not seem to be affected by the age of the structure. It is approximately 0.2 R, where R is the mean radius of the structure. In addition, the Tournemire massif is affected by tectonic faults and fractures, which in turn influence the extent of the EDZ around the old tunnel. Based on the modelling and experimental characterisation work completed, it can be assumed that the EDZ in this argillaceous Tournemire site is due to a deferred failure. At first time, when the wall of the structures are not covered the desaturation/resaturation phenomena induced a tensile failure around the new galleries. During the time, these desaturation/resaturation phenomena cause a gradual weakening of the material. The EDZ tunnel fractures may be to explain from this possible hydric damage and a decreasing mechanical strength with the time. These assumptions remain to be confirmed through coupled numerical modelling in unsaturated medium and also by using the propagation of fractures theory.
Amel Rejeb Justo Cabrera
Institute of Radioprotection and Nuclear Safety, 92262 Fontenay-aux-Roses Cedex, France
国际会议
南京
英文
648-657
2006-05-22（万方平台首次上网日期，不代表论文的发表时间）