Theoretical aspects of block stone blasting method

Abstract

Block stone excavation is a key aspect of the building materials industry, important for providing construction with durable materials and when giving aesthetic solutions to various structures and design elements. However, when excavating stone (using drilling and blasting), it is necessary to maintain its integrity for further processing and use. The conditions required for applying the method of blasting separation (split off) of stone blocks from hard rock mass were considered, which is important for improving the quality of blasted stone blocks. The rational parameters of stone block blasting with Granilen elastic tubular charges (Granilen ETCs) are presented. An approach to the preliminary assessment of stone block fracturing zone under various explosive loading regimes was determined. The relationship between the consumption of explosives and fracturing of stone blocks at possible blasthole spacing was considered. The mechanism of creating an extended rupture plane in a rock mass was studied. The decisive role of stress waves in the formation of an extended main rupture along the line of blasthole charges was established. It was shown that it is possible to localize the zone of induced fracturing by regulating the conditions for the interaction of stress waves. The results of numerical modeling of stress fields at blasting a single charge and a two-charge Granilen ETC system are presented, which made it possible to assess zones of induced fracturing and the conditionsfor the formation of a main rupture. Blasting effectiveness increases significantly due to the orientation of the expected stone block separation line parallel to the plane of the best rupture, taking into account the anisotropy of the physical and mechanical properties of granites. The study confirms the feasibility of increasing the yield of commodity blocks when selecting rational blasting parameters.

Keywords

• block rock mass
• drilling and blasting parameters
• directed flow
• charge design
• blast pulse
• blast product pressure
• stress diagrams
• dynamic strength limit
• roughness
• induced fracturing