SU1765462A1 - Method at mine working through burst-dangerous seams and rocks - Google Patents

Abstract

Usage: mining, development of outburst hazardous deposits by the underground method, carrying out of mine workings on outburst hazardous formations and rocks. SUMMARY OF THE INVENTION: During mining operations, drilling and blasting operations drill holes at a depth of not less than half of the largest size of the output cross section and explode explosive charges with short-delayed re-initiation, while destruction of the massif occurs in the mode of pre-camuflet blasting due to rational choice of length, tampering and explosives. To prevent the development and release of emissions in the process of blasting operations, an obstacle is formed from the broken rock by blasting explosive charges in a certain sequence and with a width of barrier in its upper part not less than the largest size of the output cross-section. To increase the effect, dispersed double-charge explosive charges are used. 1 hp f-ly, 6 ill.

Description

The invention relates to mining and can be used when mine workings are carried out on thin and medium thickness outburst formations and outburst formations.

There is a method of making workings on outburst formations and outburst rocks with the construction of barrier bridges in combination with special parameters of drilling and blasting operations, including the construction of bridges of metal ropes, I-beams and other materials at a distance of 3.0-3.5 m from the bottom and explosive destruction parts of rocks in the cross section of production. In this method, the fused and ejection-tolerant mining mass fills the space from the jumper to the bottom, and brakes the further development of the emission.

The disadvantages of this method are the large labor costs of assembling and dismantling the lintel after each explosion; The recommended jumper settings and blasting operations allow for the occurrence and development of an outlier.

Closest to the invention is a technical solution for carrying out

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mine workings by drilling and blasting, including drilling sets of cutting, fender and contour holes to a depth of not less than half of the largest transverse size of the excavation, loading boreholes with explosives with inert blockage from the side of hole holes and sequential blasting of charges, starting with cutting holes and ending with contouring.

A significant disadvantage of the above method is that, with the recommended parameters and order of blasting, it is allowed to discard the rock mass from the bottom and to expose it, which can lead to the development and development of a sudden outburst.

The aim of the invention is to increase the safety of work by preventing the occurrence of sudden outliers by creating a barrier (plug) from the blasted rock mass that fills the entire output section and fits snugly to the face, as well as reducing the labor intensity of work on eliminating the consequences of sudden outliers.

These goals are achieved by the fact that when mine workings are carried out on outburst formations and rocks, including drilling of cutting, auxiliary, and bore holes with a length equal to half of the largest transverse dimension of mine output I-, their loading into explosives

dredging charges B with a short-delayed reverse initiation, starting with the cut-in and finishing blasting, the destruction of the selection of the hazardous array is carried out in the mode of pre-camuflet blasting, the length of the charge and the hibernation in the blastholes are determined from relationship

D

wholesale

(D

, 9 Wnp

(2)

where Wont is the optimal line of least resistance of the firing charges relative to the newly formed lateral free surface, at which the blast index is equal to unity, m;

Wnp; - limit line of least resistance in group blasting of charges in one series of deceleration, above which a camouflet explosion occurs, m;

D is the detonation velocity of the explosive charge, m / s;

C is the velocity of propagation of a stress wave in an array of coal or rock, assumed to be equal to the velocity of the longitudinal wave in the array, m / s.

one

With a hole length equal to - L, but exceeding the total length of the stemming and charge calculated from expressions (1) and (2), dispersed double-charge charges consisting of bottom and wellhead parts are used in the boreholes, and blasting these parts at different times in the following sequence: first, the bottom parts of the charges

the first row of bore holes, then the mouth parts of the first row and bottom parts of the second row, then the mouth parts of the second row, and bottom parts of the third row, etc. The last exploded wellhead

charges of the last row of fender holes.

FIG. 1 shows the location

cutting, auxiliary and baffle

bore-holes (denoted by Arabic numerals) and

the sequence of their blasting (indicated by Roman numerals) when using solid charges in boreholes; in fig. 2 shows section A-A in FIG. one; on | yir. 3 - the location of the cutting, auxiliary and bore holes (indicated by Arabic numerals) and the sequence

blasting them (denoted by Roman numerals) when applying dispersed charges in the bore-holes; in fig. 4 shows a section BB in FIG. 3 with an indication of the sequence of blasting of parts of the dispersed charges in the boreholes; in fig. 5 - barrier (cork) from the rock mass, formed after the explosion, and its dimensions; in fig. 6 - elements of a cylindrical charge explosion funnel.

The proposed method is carried out as follows.

First, based on the specific transverse dimensions of production,

the length of the bore-holes equal to –k L Then, the length of the stemming and the charge are determined from the dependences (1, 2). If the calculated total length of the stemming and the charge will be equal to half of the largest size of the cross section1

no production at L, then apply

solid charges in boreholes. If the total length of the stemming is calculated and the charge will be

less than L, drilling and blasting operations are carried out with the use of dispersed double-charge charges in firing holes (solid charges in cutting and auxiliary boreholes). Then, in the bottomhole, drilling of the cutting-in 1, auxiliary 2 and demolition holes 3 to a length j L

The location of the holes, the magnitude of the charges are determined from the calculation to ensure the specified separation depth, the removal of the destroyed rock from the iron ore cavity and the achievement of the specified rock loosening coefficient. Charge blasting is performed in the following order. First, cut-on charges of blast 1, then auxiliary 2 with a deceleration of at least 30 ms, and then consecutive blasting of charge 3 with a permissible retarding interval. In all boreholes, reverse charge initiation is used.

When using dispersed charges in the boreholes, in the same order, blasting vrubovyh 1 and auxiliary charges 2 (Fig. 3) are produced, while blasting dispersed two-level charges in the boreholes 3 (Fig. 4). scheme: the first to explode charges of the second Rus 4, located in the bottom part of the first row of bore holes. Then, with the next slowing down stage, the charges of the first russa (the first from the hole of the hole) of the first row 5 and the second rusa of the second row 6 are blown up. After this, the next step of the slowdown blows up parts of charges 7 and 8. p yes fender holes.

The formation of a plug from the blasted rock mass occurs as follows. After the explosion of the cutting iron 1 and auxiliary charges 2, a part of the bottom is destroyed and the blasted mass is thrown towards the development, since the length of the stemming in these holes is equal to Worn-, i.e. explosive charge surplus. When blasting charges into the cut-off cavity, the length of the tamping in these boreholes is assumed to be equal to its pre-camouflage value O-zab OE (Wnp), and the distance from the charge to the side surface is equal to Wont, due to such a distance difference to free surfaces, the direction of movement of the destroyed rock will occur, mainly, as is known from the physics of the explosion, along the line of least resistance, i.e. in the direction of the lateral free surface. In the direction of production, the destruction of the destroyed mass will occur by the value of the increment in the volume of rocks when loosed by an explosion (determined by the loosening coefficient). Taking into account that the charges explode with a reverse initiation, the front of destruction of a section of the massif will extend from the bottom of the holes to their mouth, the degree of crushing of the rock and the density of the rock adjoining to the bottomhole will be the largest in the zone of location of charges, and the smallest in the mouth part, i.e. in the zone

tamping location

Similar results of the explosion will be obtained by blasting dispersed charges, in which bottom charges explode first and in the absence of other directions, the movement of the blasted rock will occur towards the lateral surface.

As a result of blasting with the specified parameters of blast-hole charges, a stopper of exploded rock mass 1Q (Fig. 5) will be formed in the prize area of the excavation, closely fitting to the face, a length equal to the depth of holes, multiplied by the factor of loosening rocks (for the most common rocks coal formation, the coefficient of loosening is 2, so the length of the plug will be L, if the depth of the holes was 1/2 L).

5 The impact of a plug from a blasted mass on the process of preventing the eruption of rock and coal is as follows. After a part of the array is separated by an explosion, local stresses are rearranged in the array with the formation of a stress recovery wave. When it falls on the newly formed surface of the slab, clamped by the destroyed mountain mass, on the border

The 5 sections of the media (bottomhole plug) will not cause the formation of a discharge wave (reflection waves in the negative phase), but flow will be inhibited, the waves will be reflected in the positive phase, and

At the contact points of the bottom with pieces of blasted rock, the transition of a recovery wave to a destroyed rock mass (plug) and the absorption of wave energy by the plug. According to wave mechanics, full absorption

5, the stress recovery wave energy will occur under the condition that the length of the plug from the destroyed rock mass is equal to or more than half the stress recovery wavelength. According to the calculations, the wavelength of the stress recovery for the conditions under consideration is 2L, and therefore, the length of the plug from the destroyed rock mass should not be less than L. If this condition is observed, the dumping of the destroyed rock mass from the surface will not occur and the sudden ejection cannot be developed

Thus, the proposed method, being simple in its technology, significantly increases the safety of work during mining for outburst-hazardous rocks and formations.

Due to the fact that the concept of the optimal and limiting line of least resistance (Wont and Wnp) is relatively rare, even in the specialized literature, we explain them in order to avoid their different interpretations. When a single charge explodes in a rock massif, the efficiency The explosion depends on the distance of the charge to the free surface. In general, the shortest distance from the center of charge to the free surface is called the line of least resistance (abbreviated L NS) and is denoted W. In FIG. Figure 6 shows the elements of the funnel of a blast hole charge located parallel to the horizontal free surface and perpendicular to the end free surface. The dotted circle represents the zone of ultimate destruction. It is proved that the largest volume of blasted rock (the highest efficiency of the explosion) will be achieved when the free surface is in position A, i.e. with W equal to the radius of the explosion funnel (indicator of

R

explosion TDT is equal to one). This line of least resistance is called optimal and is designated W0ni. When the free surface is in position B at the boundary of the zone of ultimate destruction, Л НС is called the limit and is denoted by Wnp. When the free surface is at a distance greater than Wnp, a camouflet explosion occurs. With group (primitive) blasting of charges in one series of deceleration, the value of the limiting LNS increases by 25–30% compared with a single charge Wnp, ceteris paribus.

When, the relationship between Wnp and Wont from an isosceles triangle (Fig. 6) is

W,

, 41 Woni, whence Wonr-0.71 Wnpfc yWnp.

The quantitative values of Wnp depending on the strength of the rocks are determined with a sufficiently high accuracy by calculation and experimentally by many researchers. In other words, knowing the value of Wnp, you can determine the value of Wont,

in which the indicator of the explosion is equal to one.

The damming length of the Tsab is assumed to be equal to W to ensure a uniform explosion effect on the array. When an uneven impact of an explosion occurs along the lines of Tsab and W.

In formula (1), the magnitude of the wave velocity, voltage, or velocity of a longitudinal wave in an exploding array can be determined in one of three ways: by directly measuring the velocity of the longitudinal wave in the array using an oscilloscope; filed references on the physical and mechanical properties of rocks; calculated by the formula if the values of the elastic constants of the array (Young's modulus, array density, and Poisson's ratio) are known.

Claims (2)

1. The method of carrying out mine workings on outburst formations and rocks, including drilling of cutting, auxiliary, and bore holes to a depth of not less than half of the largest size of the cross-section of the mine, loading explosive boreholes, their blocking and subsequent blasting of explosive charges with a short reverse initiation, starting with cutting and clearing boreholes, different what, in order to increase the safety of work by creating a barrier from the blasted rock, filling the cross section of the mine working and adjacent to the face, the destruction of the outburst-hazardous massif is carried out in the mode of pre-camouflage blasting, the length of the charge B B L3ap and the tamper hole in the bore holes is determined from the ratios  Wonr -p , 9 Wnp, where Wont is the optimal line of least resistance when blasting the firing charges; Wnp is the marginal line of least resistance when blasting the firing charges; D is the detonation rate of explosive charges; C is the velocity of propagation of a wave of stresses in an array, then by explosions of charges form an obstacle with a length in the upper part equal to the largest transverse size of output, 2. A method according to claim 1, characterized in that when the length of the bore holes is greater than the calculated total length of the tamping and charge, the firing holes are charged with dispersed two-level charges consisting of the bottom and wellhead parts, and these by this initially blow up the bottom parts of the charges of the first row of bore holes, then the mouth parts of the first row and the bottom parts of the second row, then the mouth parts of the second row and the bottom parts of the third, etc., and last of all they blow up the mouth parts of charges last r yes fender holes.  / /// ////// /, LG /// /// ///  Toad FIG. 2 Lain. UHHTT / UU 1 1 ZjflЈ L30D - 4 1765462 7 § h N ff ///////. FIG 6 25