Energy criteria for quasi-brittle fracture of rocks in technological processes of mining and primary processing

This study aims to develop a methodology to calculate energy criteria based on the concept of quasi-brittle fracture of rocks in technological processes of mining and primary processing. The research has shown that the Griffiths-Irwin energy criteria that are derived from solution of the equilibrium problem for a plate with an internal fracture stretched by a uniformly distributed load, refer to a special case which meets the condition of the ultimate energy efficiency of fracturing a plate with defined geometrical dimensions (length, width). Having a theoretical value, these criteria do not meet practical applications, where it is necessary to consider the energy efficiency of the rock fracture process by normal rupture cracks for each specific mining technology. It makes no sense to calculate the irreversibly expended work within the quasi-static concept of rock fracture for its practical application without taking into account the energy efficiency, this being the main conclusion of the research performed. It is suggested to estimate the energy spent on forming two new unit surfaces, which corresponds to one fracture plane and characterizes the fracture resistance of the rock material, with the criterion that includes the ultimate specific energy intensity of the fracture deformation with account of the new complex textural and structural material constants and the energy efficiency of the fracture process.