Аңдатпа
Purpose. To justify the parameters of a combined support system for temporary mine workings providing access to rib pillars during their re-mining under conditions of a technogenically disturbed rock mass at the Zhezkazgan deposit, taking into account the dynamic impact of drilling and blasting operations. Methods. The study was carried out using an integrated approach that included analytical assessment of blast wave propagation in a rock mass containing mined-out spaces, numerical modeling of the stress-strain state of the rock mass in Rocscience RS2 under different support options, and pilot-scale industrial tests with instrumental seismometric measurements using a Sigma 4+ station under the conditions of the East Zhezkazgan mine. Findings. It was established that the rock mass in re-mining areas is characterized by a limit stress-strain state, with a factor of safety of 0.60-0.90 in the absence of support. A combined support system was substantiated, consisting of 1.8 m long GFRP rock bolts installed at a spacing of 1.0-1.2 m and a 0.05 m thick fiber-reinforced shotcrete lining, which provides a factor of safety greater than 1.0 while utilizing up to 85-88% of the bolt load-bearing capacity. Pilot-scale industrial tests established that the safe distance required to preserve support functionality during blasting of fan-pattern blastholes with a charge of up to 320 kg is at least 8-10 m from the blast source, at (PPV ≤ 15 mm/s. A power-law dependence was also established for the attenuation of peak particle velocity with distance from the blast source and explosive charge mass. Originality. For the conditions of rib pillar re-mining at the Zhezkazgan deposit, the parameters of combined support for temporary workings were established for the first time with consideration of dynamic loading caused by blasting operations. A power-law dependence of seismic wave attenuation was substantiated, three characteristic zones of blast impact on the bond between the support and the rock mass were identified, and the safe distance required to preserve the load-bearing capacity of the support system was determined. Practical implications. The practical value of the study lies in improving mining safety during rib pillar re-mining through the application of an economically feasible combined support system that ensures the stability of temporary workings under intensive dynamic impact from drilling and blasting operations and preserves the bond between the fiber-reinforced shotcrete lining and the rock mass.