Coupled thermal, hydraulic and mechanical simulation with a theoretical model for swelling characteristics

Buffer material as a part of an engineered barrier system for high-level waste disposal is expected to seal the initial gaps between the buffer material and the surrounding rock during the resaturation process. Since the self-sealing ability represents the swelling characteristics of the buffer material, it is very important to estimate the swelling behavior during the resaturation process. This paper expands the theoretical model for evaluating the swelling characteristics of saturated buffer material proposed by Komine to deal with unsaturated media, and it is applied to the coupled thermal, hydraulic and mechanical (THM) model used in Japan. The new model is validated by comparison with a series of laboratory experiments quoted from the literature.