Experimental and analytical investigations on strength and deformation behaviour of red sandstone under conventional triaxial compression

In this article, a series of conventional triaxial compression tests were carried out to investigate strength characteristics and deformation behaviour of red sandstone. According to experimental results, the initial yield stress, volume dilatation stress and peak strength of the red sandstone all increase with confining pressure. Moreover, with the increase in confining pressure, the failure modes of the specimens are changed from splitting failure to compressive-shear failure. The non-linear Hoek-Brown criterion is found suitable for fitting the strength data. An elastoplastic damage model with a unified plastic hardening/softening law is developed on the basis of the experiments. As an original contribution, analytical solutions to the constitutive equations are derived for the conventional triaxial loading path under consideration. The model is validated by comparing the analytical predictions with the experimental data.