The criterion of block media strength and geomechanical back-calculation

Abstract

Relevance and problematics. The mechanism of block medium and jointed rock mass deformation and breaking differs notably from continuum mechanics ideas, making up the crucial fundamental problem of geomechanics and distinguishing it from other engineering sciences connected with the mechanics ISSN 0536-1028 «Известия вузов. Горный журнал», № 6, 2020 47 of deformable solids. However, due to poor understanding of block media breaking mechanism, rock masses strength is overwhelmingly estimated by means of empirical dependences obtained by simulation in laboratory conditions. It is apparent that this approach does not solve the crucial fundamental problem and the accuracy of predicting mechanical characteristics of jointed rock masses may reach 100%. Research methodology. Based on the earlier theoretical research by the methods of variational, integral, and differential calculus, a new mechanism of block mass breaking at a point was substantiated. It implies translation and rotational character of blocks displacement in a rock mass in the process of its deformation making it possible to substantiate the criterion of jointed rock masses breaking. Research results, analysis and recommendations for use. The research was the first to obtain the block medium strength criterion. It has been shown that block mass strength is made up of the strength along the slip joint and block rotation resistance. Besides, within some range of loads, the ultimate strength of the rock mass is proportional to the tensile strength of a structure block. The work also proposes a range of analytical dependences obtained based on the solid mechanics making which make it possible to back calculate the rock mass strength based on the curvature of the shear rupture surface and assess the full tensor of the plain field of strain by the base axes orientation.