ABSTRACT
The article is dedicated to challenging issues of drilling and blasting operations in mines at great depths from the point of the modern concept of hard rock fracture mechanisms and models. The diagram of two underground blasting development options in the block structure is presented. Basing on the analysis of the experimental data, the hard rock fracture mechanism at depth in the block structure is substantiated and the respective principles are formulated. The assumption is made with regards to the hypothetical existence of quasi-solid, which is an earlier unknown phase of the solid substance.
