<p>One of the most significant elements influencing the mechanical properties and intrinsic energy of rock is its microstructure. In order to study the effects of grain network structure on the macroproperties and strain energy parameters of marble, a 2D continuum-based Voronoi Tessellated model is employed. For this purpose, 36 Voronoi joint models with irregular, medium regular, almost regular polygon shapes and with low, medium, high, and very high densities were generated in different realizations. Then, the stress–strain curves and deformation parameters under unconfined compression were determined for each network. In the next step, for each network, three main strain energy parameters including, elastic strain energy, dissipated strain energy, and total strain energy were calculated. The results showed that in all Voronoi networks, brittle failure of marble with low joint densities occurs at lower strains. Moreover, as the density of the Voronoi joint network increases, the peak strength and elastic modulus of marble decrease. Finally, it was found that the majority of the energy that was absorbed prior to the peak strength was converted into elastic energy and stored within the rock. In rock engineering problems, microstructure can play a significant role in macroscopic behaviors and internal energy of brittle rocks.</p>