Laboratory and In Situ Simulation Tests of the Excavation Damaged Zone Around Galleries in Opalinus Clay
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- 作者：Vincent Labiouse (1)
Tim Vietor (2) - 关键词：Hollow cylinder test ; In situ simulation test ; Excavation damaged zone ; X ; ray computed tomography ; Opalinus Clay ; Nuclear waste disposal
- 刊名：Rock Mechanics and Rock Engineering
- 出版年：2014
- 出版时间：January 2014
- 年：2014
- 卷：47
- 期：1
- 页码：57-70
- 全文大小：1,054 KB
- 作者单位：Vincent Labiouse (1)
Tim Vietor (2)
1. Rock Mechanics Laboratory (LMR), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
2. National Cooperative for the Disposal of Radioactive Waste (NAGRA), Wettingen, Switzerland - ISSN：1434-453X
文摘
In the context of nuclear waste disposal in clay formations, laboratory and in situ simulation experiments were performed to study at reduced scale the excavation damaged zone (EDZ) around tunnels in the indurated Opalinus Clay at Mont Terri, Switzerland. In the laboratory, thick-walled hollow cylindrical specimens were subjected to a mechanical unloading mimicking a gallery excavation. In samples cored parallel to bedding, cracks sub-parallel to the bedding planes open and lead to a buckling failure in two regions that extend from the borehole in the direction normal to bedding. The behaviour is clearly anisotropic. On the other hand, in experiments performed on specimens cored perpendicular to bedding, there is no indication of failure around the hole and the response of the hollow cylinder sample is mainly isotropic. The in situ experiment at Mont Terri which consisted in the overcoring of a resin-injected borehole that follows the bedding strike of the Opalinus Clay showed a striking similarity between the induced damaged zone and the fracture pattern observed in the hollow cylinder tests on samples cored parallel to bedding and such a bedding controlled “Excavation-Damaged Zone is as well consistent with the distinct fracture patterns observed at Mont Terri depending on the orientation of holes/galleries with respect to the bedding planes. Interestingly, the damaged zone observed in the hollow cylinder tests on samples cored parallel to bedding and in situ around URL galleries is found to develop in reverse directions in Boom Clay (Mol) and in Opalinus Clay (Mont Terri). This most probably results from different failure mechanisms, i.e. shear failure along conjugated planes in the plastic Boom Clay, but bedding plane splitting and buckling in the indurated Opalinus Clay.