Mechanical characteristics of rocks under all-round compression

Rocks in conditions of natural occurrence are in conditions of all-round irregular stress state of compression, and in some directions and stretching, as a result of which the rocks are deformed. With the transition of mining operations to greater depths or near excavations, the formation of limiting state zones occurs, in which rocks exhibit elastic and plastic properties of bodies, destroying at the same time in conditions of heterogeneous volumetric stress states. One of the distinctive features of rocks is manifested in the heterogeneity of the deformation process, accompanied by volume changes due to the formation of microfractures and microcracks, dependence of the elastic limit and ultimate strength on the type of stress state, deviation of the shear plane from the areas of maximum tangential stresses. The loosening of rocks during deformation is most pronounced in conditions of triaxial nonuniform compression, when rocks acquire high plasticity. This book also verifies the assumptions about the nonlinear change in the values of the strain components depending on the stress level.