Abstract: Clayey rock is considered to be a reasonable geological barrier for high-level radioactive waste disposal. The research work is carried out from the aspects of both short- and long-term mechanical properties of clayey rock in the present work. Standard natural oedometer tests are carried out and basic physical and mechanical parameters such as pre-consolidation stress and compressibility coefficient are obtained. The hydro-mechanical coupling consolidation test shows that the saline has an important influence on the mechanical properties of clayey rock, and the swelling phenomenon in the hydro-mechanical coupling process is closely related to the content and type of clay minerals in clayey rock. Long-term hydro-mechanical coupled behavior of a clayey rock is studied by consolidation creep tests and the test results highlighted the creep potential of this clayey rock. Based on the test results, a creep constitutive model is established to describe the consolidated creep behavior of the clayey rock. The agreement of calculation results with the test data indicates that the model can well reflect one-demensional consolidation and reological properties of clayey rock. The research could provide significant guidance for the planning, design, site selection, and operation of the high-level radioactive waste repository built in clayey rock in China in the future.

Key words: clayey rock, creep, oedometer test, constitutive model