SU924497A1 - Method of decreasing seismic effect at blasting in open pits - Google Patents

Description

(5) METHOD TO REDUCE THE SEISMIC EFFECT IN THE MANUFACTURE OF EXPLOSIVE WORKS

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 . The invention relates to the mining industry in the development of open-pit mineral deposits, and more specifically to a method for reducing the seismic effect during blasting operations in quarries.

There is a known method for reducing the seismic effect during blasting operations at open pit mines by dividing the total charge mass into separate groups and blasting them shortly in relation to each other. In this case, the optimal deceleration interval is 60-100 ms. The disadvantage of this method is that a relatively large deceleration interval between charge groups or individual charges leads to a deterioration of the crushing of rocks, as well as to a backlog of charges, i.e. to failures.

The closest of the known technical solutions to the proposed CAREER

is a method of reducing the seismic effect during blasting operations at quarries, including drilling loosening wells with over-drilling, charging them with an explosive (BB), setting a downhole, blasting with slowing down and creating a shielding layer t2.

The disadvantage of this method is that it does not provide an increase in seismic protection of structures located near the blasting site.

The purpose of the invention is to provide enhanced seismic protection of structures located near the site of blasting operations by creating a horizontal shielding layer in the base of each working horizon.

Claims (2)

This goal is achieved by the fact that in the method of reducing the seismic effect during blasting operations in quarries, including drilling holes loosening with a drill, loading them with an explosive, setting a damming, decelerating blasting and creating a shielding layer of rocks, the rock shielding layer is created by drilling exploration wells with a hole under the lower boundary of the location of the shielding layer after which they place safety elastic sleeves, fill them with compressed air, and then drill the wells of loose With a re-drill, the magnitude of which is assumed to be twice the thickness of the shielding layer of rocks, and before charging from the exploration wells, the safety elastic sleeves are removed and all wells are blasted with an explosive, while the exploration wells are charged with dispersed charges, taking the height of the lower charges the thickness of the shielding layer, and the blasting of the lower dispersed charges is made 1-2 seconds ahead with respect to the explosions of all other charges. FIG. 1 shows a mine, a section; in fig. 2 - exploding block, cut. . A device for implementing the proposed method contains exploration wells 1, wells 2 and loosening and a horizontal screening layer 3 which is formed by clipping a certain grid of the entire area of each working horizon of the open-pit part of the quarry with vertical wells H of the ledge depth + 4 m, charging them with dispersed charges and detonation of the lower part of the depleted charges with advance in relation to the explosion of all other charges. Practically for this purpose, a network of exploratory exploration wells drilled on a grid of no more than 10x10 m can be used. In order to keep exploration wells from collapsing, after their drilling, they are placed in safety elastic sleeves (not shown), they are compressed The air is blocked by a special valve. These elastic sleeves are located in exploration wells until the entire unit is prepared for the explosion, while the loosening wells are drilled with re-drilling, the value of which is. They take at least twice the thickness of the shielding layer. Before charging all the wells, the elastic safety sleeves are removed from the exploration wells and 6 wells are charged with explosive, while the exploration wells are charged with dispersed charges, taking the height of the lower charges equal to the thickness of the shield layer, and the exploding of the lower distributed charges is produced ahead of 1-2 seconds in relation to the explosions of all other charges. The explosion of the lower dispersed charges forms like camouflage and a horizontal screening layer is created on the entire lower area of the block. The required distance between. borehole charges are determined by the formula 50iPQ where dQ is the diameter of the wells designed to create a screening layer, cm; R is the distance from the screen to the explosion, m; j3-Cp - acoustic stiffness of exploded rocks in the massif, kg / cm Xcm / s; - coefficient of rock strength - according to M.M. The way of the horse; Q is the mass of the charge of explosives, kg. The thickness of the shielding layer is calculated from the expression, prediction.) 1 compressive strength of rocks, kg / cm; charge ratio. The minimum value of the specific consumption of explosives, necessary for the formation in the massif of the rock interbed with different acoustic rigidity, is 0.2 kg / m. From here it is possible to determine the magnitude of the wellbore by the known volumetric formula q-, b the distance between the rows of wells, m. Example. The ultimate strength for compression is 700 kg / cm, you are 12 m long. To form a horizontal screen, a network of operational exploration wells is used (a b 10 and; d0 mm; 0.9; well length 16 m). The width of the shielding layer is determined by the formula: 0.785 1.7 1000 10 700 90 cm 0.9 The magnitude of the explosive charge in exploration wells is Q 0.2k tox 10 x; 0.9 18 kg. During the seismic exploration, two groups of observations are made at a quarry: with the formation of a shielding layer in the base of the ledge and without n. Measurements are performed at distances x; R 200 - m for the same mean reduced distance 5 13 m / kg 1Q where Q - mass of explosive explosion, kg. According to the average data, the oscillation speed in the presence of a screening barrier decreases from 41.3 to 20 mm / s, i.e. 2 times. The quality assessment of pilot industrial explosions shows that the presence of a horizontal screening barrier can reduce the water level in the wells of exploding blocks by 20–30%; to significantly improve the quality of development of the scarp foot, which causes an increase in the performance of the excavator by 7%. The expected economic effect from the implementation of the proposed method is approximately more than 170 thousand rubles. in year. 976 Claim Method Seismic Reduction Method. the effect of blasting operations in quarries, including drilling loosening wells, loading them with explosives, setting up stemming, blasting with retardation, and creating a shielding layer of rocks, characterized in that, in order to provide enhanced seismic protection of structures located near the place of production of explosives works by creating in the base of each working horizon a horizontal shielding rock layer, the shielding rock layer is created by drilling exploration wells with re-drilling to the bottom edge Antsi the location of the shielding layer, after which they place the safety elastic sleeves, fill them with compressed air, and then drill the loosening wells with a drill, the size of which is assumed to be twice the thickness of the shielding layer of rocks, and, all the wells are charged with explosives, and the exploration wells are charged with dispersed charges, taking the height of the lower charges to be equal to the thickness of the shielding layer, and the explosion the lower ones are produced, 1-2 seconds ahead with respect to the explosions of all other charges. Sources of information taken into account in the examination 1. Recommendations for the study of seismic hazard of mass explosions. Central Bureau of Scientific and Technical Information Minmontazhspetsstro USSR, M., 197, p. 7 2. Mosinets V.N. Crushing and seismic action of an explosion in mountainous areas. M., Nedra, 1976, p. 186 Gpototyp). u r r Pa6оУ1ш horizon i-t f / 7. g / 77U / 77L / 77/77, 77/7: jj7 / 7 fj77yZ77j77 / 777 /, 7y /. Fi9.1  J FIG. r ffSosam. .jffaSfluffo,