Experimental and Numerical Investigations on the Mechanical Behavior of Fine-Grained Sandstone

The study investigated the mechanical behavior of fine-grained sandstone. Laboratory triaxial cyclic loading tests were conducted on the sandstone under various confining pressures (5, 15, and 20MPa). The initial yield stresses sigma y were approximately 69.0-74.0% of the peak strengths under the different confining pressures, and the residual strengths sigma s were 39.5-43.5% of the peak strengths. Based on the experimental results, a coupled elastoplastic damage model for the sandstone is proposed along with a nonassociated plastic potential function. In addition, an isotropic damage evolution model has been formulated with plastic coupling for the sandstone. Furthermore, the numerical formulations of a return mapping algorithm for the implementation of the coupled model are introduced in detail. The numerical results were found to be in good agreement with the experimental data, showing that the model is able to describe the main features of the mechanical behaviors of the fine-grained sandstone.