ABSTRACT
A series of triaxial tests were performed on Berea sandstone at confining pressures up to 460 MPa and a constant pore pressure of 10 MPa. This wide range of pressures enables the porous sandstone to go through the brittle to ductile transition and high pressure embrittlement. The micromechanics of the triaxial deformation was investigated by acoustic emission (AE) measurements and microstructural observations. Our data showed that grain crushing and pore collapse induced by grain scale microcracking were the dominant micromechanical processes in the high pressure deformation. The differential stress at the onset of shear-enhanced compaction increased as the mean effective stress decreased. A linear relation between the amount of porosity reduction and the cumulative number of AE events was observed during the triaxial deformation.
