Gas permeability evolution of clayey rocks in process of compressive creep test

Low-permeability argillite is a potential material as the geological barrier in the context of radioactive waste disposal. This paper presents the influence of compressive creep deformation on gas permeability of the porous argillite by triaxial compressive creep test. The minerals and microscopic pore distribution of the argillite are analyzed from the SEM results. The triaxial compressive creep test is carried out to discover the evolutionary gas permeability of the material in the process of creep deformation and the corresponding evolution law of gas permeability is discussed closely related to both micro- and macro-characteristics of the material during creep deformation. The results suggest that gas permeability undergoes an evident decrease in initial deviatoric loading, tends to be constant in steady creep deformation, and demonstrates a slight increase in further creep when creep deformation creates cracks. The gas permeability does not exhibit a significant increase if material pores are not connected.