METHODS CALCULATION OF DYNAMICALLY STABLE AND HIT-SAFE SIZED PILLARS AT DRIVING MINE WORKINGS AND RAILWAY TUNNELS
Geomechanical processes, occurring in mountain ranges, when driving workings and underground structures of railway tunnels, significantly affect the cost and work safety. Invalid selected geomechanical parameters: sustainable spans outcrops and dimensionally stable pillars lead to an increase in the cost of mining-preparatory works and reduce the level of security due to possible unpredictable collapse of rocks from outcrops or pillars. Technical analysis of the literature was conducted to establish the stable and dynamically hit-safe pillar dimensions. It is found that when calculating the size of stable pillars confining pressure and rock strength characteristics are usually considered. Not up to standard fracturing parameters are taken into account, as well as the dynamic effect of the explosion in the formation of pillars and seismic action of the recessive explosions. This article presents a theoretical formula to determine dynamically stable and hit-safe sized pillars in underground development, derived from the energy conservation law. Substitution into the theoretical relations of slightly varying parameters has helped to get the engineering formulas for determining dynamically stable and hit-safe sized pillars depending on the fracture parameters of the seismic action of explosions, coefficient of friction between the individual and array of rock pressure. The engineering formulas for calculating dynamically stable and hit-safe sized pillars, depending on the ratio of the fortress rock, are defined. Engineering formulas are obtained for mines «Priargunsk Industrial Mining and Chemical Union» (PIMCU). The numerical values of dynamically stable and hit-safe pillar dimensions are given. A method of penetration of parallel developments in hit-safely arrays, protected by a patent for an invention, is suggested. These studies may provide a basis for the design of mining and preparatory work in different types of systems work on the deposits of ferrous, non-ferrous, rare earth metals by underground mining and construction of railway tunnels constructions in various geological and mining conditions, allowing to reduce the cost of ore production, improve the level of work safety