The initial parameters in solving problems related to the manifestations of rock pressure are rock strength indicators. The main of them is the compressive strength. As a rule, it is determined in the laboratory on samples of the rocks under study. There are also known production methods that allow to determine the ultimate strength directly on the surface of rock outcrop (face, wall of excavation, roof) or at some distance from the contour of excavation, in a borehole. However, these methods are imperfect, labor-intensive and complex ...