Excavation damage, and water and gas migration in an inherently anisotropic argillaceous rock formation

An abstract of the technical document presented at:
The 13th International Congress of the International Society for Rock Mechanics 2015
Palais des congrès de Montréal, Québec, Canada
May 10–13, 2015

Prepared by:
T.S. Nguyen and D.A. Le
Canadian Nuclear Safety Commission

Abstract

In Canada and other countries, several types of rock formation are being considered for the geological disposal of radioactive wastes. To better understand the ability of these rocks to contain and isolate the wastes, the Canadian Nuclear Safety Commission collaborates with different international research organizations and has access to experimental data from underground research laboratories (URLs) around the world. One such URL is situated in opalinus clay, at Mont Terri, Switzerland. An experiment, consisting of the excavation of a tunnel followed by water and gas injections in a test section of the tunnel, was performed at the URL. The authors have developed a mathematical model, based on the poromechanics theoretical framework, to simulate those phases of the experiment. The constitutive relationship for the stress–strain behaviour of opalinus clay takes into account its inherent anisotropy due to bedding. The model was able to capture the main features of the experiment, such as the prediction of the shape and extent of the excavation damage zone and its influence on water and gas migration.

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