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Analysis of Strength and permeability of crystalline sandstone under loading-unloading conditions

ABSTRACT In this manuscript, we investigated the strength, deformation, and permeability of crystalline sandstone during load and unload process, and come to some conclusions as follows: the ultimate strength, axial strain and residual stress gradually increase with the increase of confining pressure. The linear Mogi-Coulomb strength criterion has a good regression effect, the Mogi-Coulomb stress circle and envelope is drawn, and the sample failure form is simple, all of which are a single shear failure. The Poisson’s ratio and deformation modulus were used to analyze the deformation characteristics of samples during loading and unloading. The permeability of the sample has a corresponding relationship with the damage deformation evolution, the permeability is almost zero before the axial stress reaches the yield strength, the permeability increases slowly when the rock specimen reaches the yield stage late, the permeability increases sharply after the rock sample was destroyed.