Abstract: [Objective] The work is devoted to the study of irreversible deformation of artificial samples subjected to a set of standard experiments, with an aim to study their mechanical properties. The principal idea of the study is related to the preparation of an artificial material with an established constitutive behavior model. The existence of such well-described material provides future opportunities to conduct controllable experiments on various mechanical processes in rock-like material for further development and validation of theoretical models used in rock mechanics. [Methods] A set of artificial samples was prepared for careful assessment through a number of loading tests. Experimental work was carried out to determine the rheological properties under conditions of triaxial compression tests and uniaxial tension. Triaxial loading tests are completed for 9 samples with varied radial stress levels (0–5 MPa). The samples are loaded up to the yield point with control of radial and volumetric strain. The experimental results, which    contain the obtained interrelationships between axial and radial stresses and strains, are analyzed using the Drucker-Prager yield surface. Material hardening is taken into account through the non-associated plastic flow law with the cap model. Numerical modeling of sample loading is performed through the finite difference method. Mathematical model parameters are adjusted to minimize the discrepancy between numerical modeling results and experimental data. Design of a series of experimental studies necessary to determine all the parameters of the model has been studied. [Results] It is shown that the formulated mathematical model allows to reliably reproduce the inelastic behavior of the studied material and can be used to solve a set of applied problems in continuum mechanics, the problem of numerical simulation of hydraulic fracture growth in an elastoplastic medium in particular. It was found that for the entire range of applied lateral loads (0–5 MPa), the elastic limit varied from 2 to 4 MPa, after which the material began to behave plastically. It was also determined that at lateral loads ≥ 3 MPa, compaction began to appear in the material beyond the yield point. Judging by the dependence of volumetric strains under a lateral load equal to 1.4 MPa, compaction should begin to appear even at lower lateral loads than 3 MPa. [Conclusion] Taking the plastic behavior of the material into account is necessary when moving on to modeling the hydraulic fracturing process in such a material, and the resultant plasticity parameters for the model material can be used for numerical modeling of elastoplastic deformation of the rock under consideration, including the processes of hydraulic fracture growth in a poroelastoplastic medium. [Significance] The suggested procedure to interpret results of experimental studies can be used for further numerical modeling of mechanical processes in rock masses with inelastic strain accumulation. This opportunity can increase the reliability of geomechanical models used for the optimization of hydrocarbon fields development.