RU2265799C1 - Method for blasting of benches under chain mats - Google Patents

Abstract

FIELD: mining industry, in particular, in mining of hard rocks in restricted condition, when it is necessary to exclude scattering of the blasted rock mass.

SUBSTANCE: the method consists in drilling of blast holes, loading of them, sheltering of the area to be blasted by mats of anchor chains and blasting of rocks. According to the invention, the method consists in drilling of blast holes, loading of them, sheltering of the area to be blasted by mats of anchor chains and blasting of rocks, after loading of the holes a horizontal chain mat is placed on the bench surface, and with the aid of a beam with flexible lugs positioned on the edge it is fastened by the anchors installed in not deep holes outside the block to be blasted, then a chain mat is placed on the side slope of the bench so that the lower edge would be laid on the bench bottom at least 2m long, and its upper edge is joined to the horizontal chain mat outside the prism of probable caving. After that the blast network is mounted over the shelter, and the sheltered bench is blasted. The claimed method of blasting of benches under a shelter provides for a rock-breaking without scattering of pieces under the bench slope.

EFFECT: enhanced safety of blasting due to prevention of scattering of rock pieces under the slope of the benches.

2 dwg

Description

The invention relates to the field of mining, in particular to the development of strong rocks in cramped conditions, when it is necessary to exclude the spread of blasted rock mass - when re-preserving temporarily idle sides of deep quarries, blasting near cyclic-flow technology complexes, posting sides of deep rock excavations in road construction etc.

Known methods of blasting rocks with the installation over the blasted surface of special shelters of various designs or filling the ledge surface with soil, automobile tires in bulk in several layers to reduce the expansion of pieces of rock [1]. Their main disadvantages are the prevention of pieces from expanding only from horizontal platforms, while a significant outburst of rock mass comes from the escarpment of an exploding ledge.

The method of blasting in a clamped medium onto a retaining wall from the side of the escarpment of the ledge, excluding the expansion of pieces from the escarpment of the ledge, is often unacceptable due to the lack of sites of sufficient width.

The closest to the essence of the problem is the method of blasting under the shelter in the form of mats made from waste anchor chains and capable of passing explosive gases, thereby reducing the impact on the shelter. The elasticity of the chain mats during the expansion of the rock from the explosion does not allow tearing individual pieces from the total mass, the loosened rock mass is tightly wrapped around the mat and kept in a compact state. The inertial resistance of the compact mass of the rock, reinforced by the mass of the shelter, balances the force of the explosive shock. This explains the complete absence of scattering of individual pieces, and the whole loosened rock mass is thrown up by an explosion 1-5 m up and falls back [2].

The disadvantage of this method is the large expansion of pieces of blasted rock mass under the escarpment of the ledge, since only a horizontal surface is covered.

The technical problem, the solution of which the invention is directed, is the elimination of the expansion of pieces of rock to the escarpment of ledges during blasting.

The problem is achieved in that in the method of blasting ledges under a shelter, including drilling blast holes, loading them, covering the blast volume with mats from anchor chains and blasting rocks, according to the invention, after charging wells on the surface of the ledge, a horizontal chain mat is placed and using a beam with elastic eyes placed along its edge, is fixed to anchors installed in shallow wells outside the blasting block, then a chain mat is placed on the side slope of the ledge so that the lower edge Ai lay on the bottom of the ledge with a length of at least 2 m, and its upper edge is connected to a horizontal chain mat outside the prism of a possible collapse, after which the explosive network is mounted on top of the chain mats and the covered ledge is blown up.

In Fig.1 shows a ledge of rocks, covered with chain mats from anchor chains in the context; figure 2 - node a in figure 1.

The method of blasting ledges under the chain mats is as follows.

The blast ledge 1 is drilled with blast holes 2 and shallow (2-4 m) wells are drilled in the first row of the next blasting block, into which the anchors 3 are installed using eyelets 4. The anchors can be made of scraps of thick-walled pipes, for example, second-hand ones drill rods of cone drilling machines. After that, blast holes are charged 2. Blast holes that are extreme from a lateral slope are charged with a reduced bulging charge, in which the explosion energy is sufficient to displace the rock toward the free surface, and this displacement will cover the entire thickness of the rock between the charge and the surface and will be accompanied by its crushing with bulging, without scatter [3].

After charging blast holes 2, ledge 1 is prepared for explosion, for this, the detonating cord or waveguides from the well fighters are turned into rings and hidden in the upper part of the stemming, so as not to damage during subsequent work to shelter the ledge. After that, a horizontal chain mat 5, made, for example, of anchor chains, is placed on the surface of the exploded section of the ledge 1, using a heavy-duty truck crane, since 1 m ^{2 of} chain mats from anchor chains has a mass of 100 to 230 kg. Using elastic eyes 6, made of, for example, used car tires fixed to a beam 7 at the edge of the chain mat 5, it is secured to the anchors 3 by putting on elastic eyes 6 through the eyes 4. Then, a chain mat is placed on the side slope of the ledge 1 8 so that the lower part is laid on the bottom of the ledge at a length of at least 2 m. Its upper part is equipped with a beam 9 with connecting elements 10, for example, hooks. Using the beam 9, the chain mat 8 is lifted by a crane above the surface of the ledge, its upper edge with the beam 9 is pulled out by the prism of a possible collapse 11 and laid on a horizontal chain mat 5. After that, the connecting mats 10 connect the chain mats 5 and 8 together.

After installing the chain mats, all equipment and workers are removed outside the danger zone and proceed with the installation of the explosive network. To do this, through the gaps in the chain mats, detonating cords or waveguides are removed from the wells and an explosive network is mounted on top of the chain mats.

In an alternating explosion of loosening charges, the bulk of the explosion energy is spent on crushing rocks and displacing gas-permeable chain mats 5 and 8. And the chain mat 8 begins to shift first, since the rock swelling begins with the escarpment of the ledge. Through the beam 9 and the connecting elements 10, the force is transmitted to the chain mat 5. Thus, the combined system of chain mats 5 and 8 comes into effect. and kept by them in a compact state. The chain mats 8 and 5 are held from the offset by the ledge of the ledge by anchors 3 through the elastic eyes 6 and the beam 7, so the chain mats will begin to slide along the intumescent rock mass and, due to friction forces, provide additional resistance to the movement of individual pieces. The inertial resistance of the compact mass of the rock, reinforced by the mass of the shelter from the chain mats, balances the force of the explosive shock. The elastic eyes 6 soften a sharp jerk of the chain mats, reducing the load on the anchors 3. The height of the rock toss with cover from the chain mats 5 and 8 depends only on the thickness of the blasting layer and the coefficient of loosening of the rock, since the amount of rock swelling after loosening depends on the latter. Given that the coefficient of loosening of rocks during blasting in the clamp is 1.05-1.1, and the height of the blasted ledges is 10-15 m, a chain mat of 8 in 2 m on the bottom of the ledge will be enough so that it does not go beyond blasted rock mass.

After the explosion, chain mats with eyes removed from the anchors, pulled from the surface of the rock mass with bulldozers. In case of difficulty, the chain mats are disconnected and removed in parts from the rock mass. Anchors are removed from the wells, drilled to the design depth and used as blast holes in the first row of the next blasting unit.

Thus, the inventive method of blasting ledges under the chain mats provides rock breaking without scatter pieces to the slope, thereby allowing to solve the problem.

Sources of information

1. Instructions for the production of blasting with protective shelters. M .: CPES, 1987.

2. Avdeev F.A., Yuzhakov S.V. A new type of protection against the expansion of pieces of rock during explosions // Blasting No. 61/18. M .: Subsoil. 1966. S.218-223 (prototype).

3. G.P. Demidyuk. Application of the energy principle to the calculation of borehole charges in quarries. // Explosive business No. 62/19. M .: Subsoil. 1967. S. 36-51.

Claims (1)

A method of blasting ledges under chain mats, including drilling blast holes, loading them, covering the blasting volume with chain mats from anchor chains and blasting rocks, characterized in that after charging the wells, a horizontal chain mat is placed on the ledge surface using a beam with elastic eyes, placed along its edge, is fixed to anchors installed in shallow wells, then a chain mat is placed on the side slope of the ledge so that its lower edge lies on the bottom of the ledge at least 2 m long, and the upper th edge is connected to the horizontal chain mat outside the prism of possible collapse, then make an explosive network installation on top of the chain mat and blow up covered ledge.

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