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- Title
Creep Deformation and Gas Permeability in Fractured Claystone Under Various Stress States.
- Authors
Chen, X.; Xie, S. Y.; Zhang, W.; Armand, G.; Shao, J. F.
- Abstract
Clayey rocks with low permeability are investigated as a potential geological barrier for underground disposal of radioactive waste. Subjected to thermo-hydromechanical loads, damaged zones can be created around underground structures. It is crucial to investigate the evolution of permeability in those critical zones. In this study, an original experimental study is performed on the Callovo-Oxfordian (COx) claystone investigated in the French radioactive waste disposal project. A cylindrical sample is first subjected to a confining pressure, then to different values of shear stress until the creation of a planar fracture along the height. Creep tests are conducted under the different steps of shear stress. Gas permeability is also measured during the creep phases. Unloading–reloading steps of confining pressure are further realized to investigate the gas permeability change of fractured sample. The correlation between gas permeability variation and fracture opening is analyzed. Highlights: An original direct shear test is performed in order to investigate the creep deformation and permeability evolution of sound and fractured claystone. The creep strain rate is not significantly enhanced by the creation of fracture and it is mostly controlled by frictional sliding along fracture surface. The shear sliding leads to a normal opening of fracture leading to a significant increase of gas permeability. There is a clear correlation between gas permeability evolution and fracture opening and closure.
- Subjects
RADIOACTIVE waste disposal in the ground; RADIOACTIVE waste disposal; STRAINS &; stresses (Mechanics); PERMEABILITY; ROCK permeability; CREEP (Materials)
- Publication
Rock Mechanics & Rock Engineering, 2022, Vol 55, Issue 4, p1843
- ISSN
0723-2632
- Publication type
Article
- DOI
10.1007/s00603-022-02774-2