The combination of the asymptotic method of averaging the model for Goodman deformability of the unit allows you to crack by calculation reproduce compression chart for rock fracture to the system. This figure is more correct than the experimental curve obtained by treatment with a standard mechanical test results, as in the course of its construction is not supposed to homogeneous deformation in small volume. The physical interpretation of the initial portion of the chart, this Walsh, allows to evaluate porosity of the rock.