The application of a Matsuoka-Nakai-Lade-Duncan failure criterion to two porous sandstones

We summarize two suites of recent true triaxial tests in two porous sandstones, Coconino and Bentheim. One suite of tests conducted under constant σ₂ and σ₃, which revealed the effect of σ₂ and σ₃ on rock failure. The other suite of tests, performed under constant Lode angle, determined the failure dependencies on mean stress and Lode angle. Building and modifying failure descriptions by Matsuoka-Nakai (MN) and Lade-Duncan (LD), an explicit failure criterion (modified-MNLD) that generalizes a class of failure forms is used to fit the novel loading path data of both sandstones. The determined failure descriptions fit both rocks well over a wide range of failure conditions. Then, the generated failure descriptions were further used to predict failure conditions under the constant σ₂ and σ₃ loading path. The predictions by the modified-MNLD are generally consistent with these data. The predictions also successfully replicated the variation of σ_1,peak with σ₂ under constant σ₃, suggesting the potential of the modified-MNLD to clarify the effect of σ₂ on rock failure.