Large-Scale Blasts Seismic Load on Natural and Technical Objects

Seismic safety of large-scale blasts is one of the most important geoecological aspects of open-cut mining. Seismic load of largescale blasts which defines integrity of industrial and residential objects is of special interest. The work represents evaluation of negative seismic impact of large-scale blasts at «Neryungrinskiy» open-cut on the natural and technical systems located in the blasting zone. The main characteristic of evaluated seismic load of explosion wave damaging natural and technical constructions is the maximal value of vectorial velocity of earth movement during large-scale blasts. Determination of permissible speed fluctuation included its frequency content, as waves of different frequency with equal values of drift velocity are dangerous to various extents. Peculiarities of vibrational frequency of the constructions caused by seismic load of the blasts and self-induced vibrations were taken into account while evaluating seismic load. Considering spectral content of the vibrations caused by the blasts and self-induced vibrations values of gas containers and constructions of compressor station, it’s necessary to point out that the frequencies differ for 1,5—2 times and this is the favourable factor because of impossibility of resonant phenomena occurrence. Determination of permissible velocity included swinging of the building. Swinging is understood as ratio of maximal shift of the measured at the top points of the constructions to maximal shift of the foundation ground. According to the results of direct measurement, swinging does not exceed 1,5 times that’s why it is possible to found on prevailing values of ratios, calculated by means of experimental way as statistically explained. The permissible velocity should be accepted as Uperm — 1,25 cm/s. for the objects. By “swing” we understand the correlation of maximum offset measured on top of construction to maximum offset of subfoundation. According to direct measurements offset rate stays below 1,5, therefore we can rely on prevailing experimentally obtained value of correlations and set allowable speed to Ual = 1,25 sm/s.