Relationship Between Permeability and Strain of Sandstone During the Process of Deformation and Failure

The permeability of the rock specimen during the process of deformation and failure is a dynamic evolution, and it relates with the growth and coalesces of micro-cracks within the rock. Although extensive researches have been conducted on the relationship between the stress–strain and the permeability, the deformation of the specimen should be taken into account for the evaluation of the permeability. In this study, experiments on the hydro-mechanical coupling of sandstone are carried out. Change of the permeability with the axial, lateral and volumetric strains is investigated. The experimental results show that the change of the permeability during the process of deformation and failure has apparent phases, and the evolution of the permeability is closely correlated with the strain. According to the experimental data, two kinds of empirical equations are fitted to better describe the relationship between the permeability and the strain. One is the polynomial equation used to simulate the phase of compression of rock specimens, the other is exponential equation used to simulate the rest of deformation phases. The obtained equations are just the empirical ones for the sandstone and are not for the universal application.