Characterising and modelling the excavation damaged zone in crystalline rock in the context of radioactive waste disposal

Abstract

This paper describes current knowledge about the nature of and potential for thermo-hydromechanical-chemical modelling of the Excavation Damaged Zone (EDZ) around the excavations for an underground radioactive waste repository. In the first part of the paper, the disturbances associated with excavation are explained, together with reviews of Workshops that have been held on the subject. In the second part of the paper, the results of a DECOVALEX 1 research programme on modelling the EDZ are presented. Four research teams used four different models to simulate the complete stress-strain curve for Avro granite from the Swedish Äspö Hard Rock Laboratory. Subsequent research extended the work to computer simulation of the evolution of the repository using a 'wall block model' and a 'near-field model'. This included assessing the evolution of stress, failure and permeability and time dependent effects during repository evolution. As discussed, all the computer models are well suited to sensitivity studies for evaluating the influence of their respective supporting parameters on the complete stress-strain curve for rock and for modelling the EDZ.

Seismic travel-time and attenuation tomography to characterize the excavation damaged zone and the surrounding rock mass of a newly excavated ramp and chamber

“…The dimension of the EDZ depends essentially on the rock mass under consideration (e.g. geology, mechanical properties), the excavation method (such as drilling and blasting, tunnel boring machine (TBM)) and the characterization method of the EDZ [1]. Information on the EDZ is important for the evaluation of construction stability.…”

Comprehensive evaluation of excavation-damaged zones in the deep underground caverns of the Houziyan hydropower station, Southwest China

“…This zone affects the mechanical behavior of the surrounding rock masses in the construction area, thereby reducing the stability and safety factor, and increasing the probability of structural deformation and failure. Different definitions for the damaged or disturbed zone have been proposed (Kelsall et al 1984;Pusch and Stanfors 1992;Martini et al 1997;Bäckblom and Martin 1999;Martino and Chandler 2004;Tsang et al 2005;Hudson et al 2009). Based on these definitions, disturbed zones are generally classified as highly damaged zones (HDZs), excavation-damaged zones (EDZs), and excavation-disturbed zones (EdZs), as shown in Fig.…”

A multiple-code simulation study of the long-term EDZ evolution of geological nuclear waste repositories

“…Five research teams studied this simulation problem, using a wide range of numerical methods, including boundary element, finite element, finite difference, particle mechanics, and cellular automata (Table 1). A summary of the entire Task B and a detailed presentation of the application of the new cellular automata approach are provided in accompanying papers by Hudson et al (2008) and Pan et al (2008), respectively. The detailed definition of this simulation problem and the complete set of results are reported in Rutqvist et al (2008a).…”