Abstract:
The swelling performance of highly compacted bentonite deteriorates due to infiltrating rock groundwater and chemical components during its long-term operation, ultimately posing a threat to disposal safety. The recent researches on the physical interaction between compacted bentonite and pore solution are reviewed based on the phenomena related to the influences of the pore solution on buffering properties. The results show that the physical mechanism of the pore solution on highly compacted bentonite includes swelling of crystal layer, swelling of diffusion double layers and adsorption effects. The effects of the pore solution on the swelling of crystal layer are related to its concentration, and they are promoted at low concentration and inhibited at high concentration, which depends on the difference between the suction and the critical suction of the poresolution. The inhibition of the pore solution on the swelling of double layers is the main factor for the enlarged pore channels, higher permeability and diffusion coefficients. The pH change and nuclide hydrolysis alter the adsorption characteristics, while the competitive background ion adsorption reduces the nuclide capacity of bentonite. The current shortcomings include parameter generalization for pore solution effects, effective porosity quantification and adsorption models. Therefore, the further optimization of chemical parameters of pore solution in the constitutive model, the clarification of the equivalent quantification of the pores at different scales, and the establishment of a multi-component competitive adsorption model under the constraint of compacted bentonite are still the key directions for the further researches in the future.