Abstract

Argillaceous rocks are candidate host and/or cap formations for the geological disposal of nuclear wastes in many countries, including Canada, France and Switzerland. The understanding of the long term mechanical behaviour of such rocks is an essential requirement for the assessment of their performance as a barrier against radionuclide migration. Due to the existence of bedding, argillaceous rocks are inherently anisotropic and the development of stress-strain models for their mechanical behaviour needs to take this anisotropy into account. This paper presents two examples of the practical implementation of stress-strain relationships in finite element models to simulate the excavation damage zones (EDZ) in bedded argillaceous rocks. The first example concerns the EDZ around a micro-tunnel in Opalinus Clay, in Switzerland. The second example relates to the EDZ around the century-old tunnel in Tournemire shale, in France. Both examples show the importance of developing robust stress-strain models that can replicate inherent anisotropy of the rock, and of calibrating and validating the models with a comprehensive set of laboratory experiments. The second example shows the additional influence of dessication and fault zone on the extent and shape of the EDZ.

摘要

在包括加拿大，法国和瑞士在内的许多国家，核废料的地质处置中，弧状岩石是候选的寄主和/或盖层。了解此类岩石的长期力学行为是评估其作为放射性核素迁移屏障的性能的基本要求。由于存在地层，所以泥质岩本来就是各向异性的，因此，针对其力学行为建立应力-应变模型需要考虑到这种各向异性。本文提供了两个实例，它们在有限元模型中实际实现了应力-应变关系的模拟，以模拟层状泥质岩石的开挖损伤区（EDZ）。第一个示例涉及瑞士Opalinus Clay的微隧道周围的EDZ。第二个示例与法国Tournemire页岩中具有百年历史的隧道周围的EDZ有关。这两个示例都显示了开发鲁棒的应力应变模型（可以复制岩石的固有各向异性）以及通过一组全面的实验室实验对模型进行校准和验证的重要性。第二个示例显示了干燥和断层带对EDZ范围和形状的附加影响。