Estimation of the Brittle Fracture Zone Generated by Concentrated Charge Blasting Near a Free Surface

摘要

It is of current interest in mining to describe a destructive effect exerted on hard rock by an underground explosion, which depends on the properties and structure of rock. This study presents an analysis of the blast action of a concentrated charge on monolithic brittle rock where destruction develops in the form of fracturing. Based on the linear elastic fracture mechanics (LEFM), the authors have developed a model enabling estimation of kinematics of cracks that propagate from the explosion epicenter and reach the free surface. The problem includes a simplifying assumption of axial symmetry of cracks. The calculations performed for a medium and a charge with particular parameters have shown that the suggested approach allows the estimation of the shapes of cracks and time dependence of their sizes, as well as the shape and size of a blast crater generated by concentrated charge blasting near free surface.