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Abstract In order to understand the relationship between rock permeability and deformation under hydro- mechanical coupling，a servo-controlled triaxial rock mechanics test system is employed to investigate the steady-state permeability of sandstone under various confining stresses and osmotic pressures. Permeability characteristics(associated with brittleness and ductility) and the relationship(associated with permeability，stress and strain) are analyzed based on permeability-strain curves of sandstone samples. The results show that：(1) The initial permeability and peak strength of sandstone vary with the confining stress and osmotic pressure under hydro-mechanical coupling. (2) In the complete stress-strain process under hydro-mechanical coupling，the permeability decreases with the increase of axial strain in the beginning. However，at the elastoplastic stage，the curves of permeability vary with different confining pressures，i.e. dropping，constant，and rising. A new phenomenon in the horizontal curve of permeability is observed in rock seepage triaxial test. (3) Under high confining pressure，if local compaction band is formed，the trend of permeability is determined by coalescence of microcracks and skeleton crushed after the elastoplastic stage. (4) Coalescence of microcracks plays a positive role in increasing permeability，but the formed compaction band resultant from crushed skeleton will decrease the permeability. (5) After the plastic stage，the permeability changes from increase to decrease prior to the critical state of brittle-ductile transition when confining pressure increases. (6) Volumetric strain of rock has certain influences on the permeability. For the phenomenon that permeability decreases when the volumetric strain increases in the brittle-ductile transition stage，further study is needed where more accurate measurement of volumetric strain is required.
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Received: 11 January 2013
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2013, Vol. 32 
