Abstract:In order to gain a better understanding of coupled thermo-hydro-mechanical(THM) processes in indurated clays being considered in various countries as host rock for the disposal of high-level radioactive waste,a heating experiment named HE-D is being conducted on the Opalinus clay at the Mont Terri Rock Laboratory in Switzerland. An electric heater of 5.4 m length has heated the clay rock over more than one year. The maximum temperature of 100 ℃ is reached at the heater/rock interface. During the experiment,temperature,pore water pressure,gas migration,and deformation in the clay rock have been monitored by means of more than 80 instruments installed in 24 boreholes. Thermal expansion of the heated rock was observed. In the heated region at distance about 1 m to the heater,the pore water pressure increased from about 1 MPa to 4 MPa. The responses of the clay rock to heating were simulated by coupled THM modeling. Preliminary results of the field measurements and the numerical calculations are presented.