The Mont Terri HE-D Experiment as a Benchmark for the Simulation of Coupled THM Processes

This contribution presents results of the advancement status of one of the tasks of the new DECOVALEX phase (D-2015). The task aims to improve the understanding of Thermo-Hydro-Mechanical (THM) processes in bentonite buffer and in argillaceous host rock. This communication focuses on the first step that addresses the performance of the HE-D heating test in Mont Terri (Switzerland). Two heater elements were emplaced directly in the Opalinus clay without bentonite buffer. The heating phase started with a heating power of 325 W/heater, which was increased to 975 W/heater after 91 days. Heating was stopped after 339 days and monitoring was continued during the cooling phase until the 518th day. Observations are available for temperature, pore water pressure and rock displacement. A total of eight modelling teams are involved in comparative calculations of the THM processes with different codes. The comparison of the results for the temperature field shows a good agreement between the teams and the simulated temperatures are close to the measurements. Simulated pressure and displacement values show larger differences.