Coupled thermo-hydraulic pulse tests on two reference Belgian clay formations

Boom and Ypresian clays are being studied in Belgium in connection with the design of a repository for radioactive waste. Within this context, thermal impact may play an important role on the behaviour of these low-permeability clays. To evaluate this impact, heating pulse tests on intact borehole samples were carried out using an axi-symmetric and constant volume heating cell with controlled hydraulic boundary conditions. Attention is focused on the time evolution of temperature and pore water pressure changes along heating and cooling paths –i.e., pore pressure build-up during quasi-undrained heating and later dissipation to the applied hydraulic boundary conditions– .A coupled thermo-hydro-mechanical finite element program was used in a first stage to determine thermal parameters by back-analysis and then to simulate selected experimental results on Boom clay.