Failure characteristics of two porous sandstones subjected to true triaxial stresses

We conducted an extensive suite of true triaxial experiments in two porous sandstones, Bentheim (porosity ≈ 24%) and Coconino (17.5%). Our experiments demonstrate that failure of both sandstones is not only a function of σ 3 but also of σ 2 . For a given σ 3 , σ 1 at failure ( σ 1,peak ) increases as σ 2 is raised above σ 3 between tests. The σ 1,peak reaches a peak as σ 2 is about halfway between σ 3 and σ 1 and then gradually decreases such...