Task B1 is geared towards the understanding of Thermo-Hydro-Mechanical (THM) processes in a bentonite buffer and an argillaceous host rock. It is based on the performance of 1) the HE-D in situ heating test (rock only), 2) laboratory column tests on bentonite pellets and 3) the HE-E in situ heating experiment (integrating buffer materials and host rock), the final objective of the Task. The two in situ experiments were performed at the international Mont Terri rock laboratory in Switzerland.
Eight modelling teams are involved in Task B1. They are shown in the table below together with each team’s principle investigator, the funding organisation (F.O.), the country of origin and the code used in the framework of the Task:
This part is based on the performance of the in-situ HE-D heating test. The HE-D test was run in 2004-2005, including 340 days of heating. The temperature field was measured in the heating borehole (about 16 temperature sensors) and in the rock mass (about 23 temperature sensors). The associated pore water pressure and strain response of the rock mass was monitored in 11 piezometers and 2 extensometers (containing about ten strain measurement intervals each). This test is described by Wileveau (2005) and the HE-D was led by ANDRA (Agence nationale pour la gestion des déchets radioactifs).
The buffer materials used in the HE-E in situ experiment are also characterized in the laboratory. Different column tests (Villar et al. 2012) with a height similar to the buffer material thickness in the HE-E are currently running. They are designed to mimick the boundary conditions prescribed at the heater side and at the Opalinus Clay side. Iso-thermal and non-isothermal infiltration tests are considered. The mechanical behaviour of the buffer materials will have to be derived from information available in the literature.
This part is based on the performance of the in-situ HE-E heating test. In the HE-E, heating started in July 2011 and is planned to go on at least until July 2014. The HE-E experiment was designed to be used as a modelling exercise to validate different THM formulations. The instrumentation in the HE-E consists in:
The HE-E experiment is performed at the location of the previous VE experiment, which is described in Mayor et al. (2005) and Mayor and Velasco (2008) and in the final report of the previous DECOVALEX project (Garitte et al., 2012). Information about the HE-E experiment may be found in Gaus et al. (2011) and Teodori et al. (2011). The HE-E is an in situ experiment that is part of the PEBS (Performance of Engineered Barrier Systems) project, funded by the seventh framework project of the European Commission. The HE-E experiment is led by NAGRA.
For further information, please contact the task leader, Benoit Garitte (email@example.com)