RU2271513C2 - Method for driving of raises with rock breaking by deep-hole charges - Google Patents

Abstract

FIELD: mining industry, applicable in driving of horizontal workings.

SUBSTANCE: compensation and blast holes are drilled in a rock mass over the entire length of the raise. The blast holes are charges partially or completely, and they are subjected to a short-delay blasting into compensation holes and then the formed compensation cavities. The interval of slowing-down between the holes blasted in succession, depending on the detonation characteristics of the explosive, charge diameter, physico-technical properties of the rock mass, height and diameter of the newly formed compensation cavities should provide for breaking of the rock from the mass and full outburst of the rock mass from the cavity, i.e. to prevent the pressing effect of the rock mass in the contour of the raise.

EFFECT: determined the interval of slowing-down between the holes blasted in succession with prevention of the rock mass pressing in the contour of the raise, which allows to increase the height of the blasted section and enhance the physico-technical properties of the raise driving.

1 dwg, 1 ex, 2 tbl

Description

The invention relates to the mining industry, in particular to methods of sinking uprising mine workings, and can be used for sinking horizontal mine workings.

A known method of sinking rebellious with breaking the rock borehole charges to compensation wells. The essence of the method consists in drilling compensation and blast holes, loading blast holes into sections and blasting them (see the Explosive Handbook. / Ed. By B.N. Kutuzov. - M., Nedra, 1988, pp. 377-381).

However, in this method it is not indicated instantly, shortly or slowly that the wells are blown up, which retardation intervals must be applied between the blasting of the wells. Therefore, the height of the slaughtered section, as a rule, does not exceed 4 m (see table. 12.15) and the rock is broken mainly for the face of the rebellion. The low height of the section, as indicated in the directory, leads to repeated repetition of loading, blasting and airing operations, pinch and deformation of the wells, pressing in the rock, destruction of the mouth of the rebellion.

The closest technical solution is a method of sinking rebellious rock breaking downhole explosive charges into compensation wells, including drilling compensation and blast holes, loading blast holes in sections and blasting wells with a delay interval of 0.5-1.0 s (see Mosinets V.N. , Pashkov AD, Latyshev VA The destruction of rocks. - M., Nedra, 1975, p. 158-160): The height of the section in this case reaches 3-5 m, and sometimes 20-25 m, which partially eliminates the disadvantages given above.

However, in the method, the deceleration interval for the charges of the hole wells, equal to 0.5-1.0 s, was selected experimentally when driving rebels in the mines of the Leninogorsk Combine, i.e. for rocks defined by their physical and technical properties. In addition, the deceleration interval does not depend on the volume of the compensation cavity, detonation characteristics of the explosive, the diameter of the explosive charge, and the height of the beaten section.

A method is proposed for driving rebellion with rock breaking with borehole explosive charges, including drilling compensation and blast holes, loading blast holes and blasting them into expansion wells or cavities, characterized in that the deceleration interval between successively blown wells is determined taking into account the need to prevent the pressing effect rock mass in the contour of the rising from the expression

where τ _about - the time required for breaking the rock from the array, s;

τ _In - the time required for the ejection of the rock mass from the compensation cavity, C.

where W is the LNS or the distance between the explosive charge and the wall of the compensation cavity, m;

D — detonation velocity of explosives, m / s;

ρ _in - loading density, kg / m ³ ;

d _s - diameter of explosive charge, m;

μ is the coefficient of friction between the elements in the array;

ν is the Poisson's ratio of the individual;

ρ is the bulk mass of the rock, kg / m ³ ;

F - an indicator of fracturing of the array;

P is the rock pressure at the blast site, Pa;

C is the velocity of the longitudinal wave individually, m / s;

N _p - the height of the compensation cavity, which produce blasting, m;

d _p - diameter of the compensation cavity, m;

ρ _n - volumetric mass of crushed rock in the contour of the compensation cavity at the time of its release, kg / m ³ ;

π = 3.14.

The proposed method allows for the penetration of uprising deep wells with an increased section height by determining the retardation intervals between successive blasts of wells, which ensure the breaking of the rock from the massif and the complete ejection of rock from the newly formed compensation cavity.

The essence of the method is illustrated in the drawing and is as follows. One of the reasons for drilling uprising wells in small sections (up to 3-4 m) or frequent pressing in of uprising sections up to 10-20 m long with blasted rock mass is the incorrectly chosen retardation interval between successively blown wells. The deceleration interval should be such that this time is sufficient to break the rock into the compensation cavity, and then under the action of gaseous detonation products to completely eject the crushed rock mass from the cavity. With a smaller value of the deceleration interval, the rock ejected by the previous borehole charge is compacted by the rock of the subsequent explosive charge, then the next charge, etc. As a result, after the explosion of the entire set of wells, the coefficient of loosening of such rock mass will be less than 2 and it will not spill out of the uprising.

The proposed method is as follows. Initially, a set of compensation and blast holes is drilled to the entire height of the uprising. Moreover, the distance between the wells is chosen so that the volume of the compensation space (well or cavity) is equal to at least the volume of the ejected rock. The retardation interval between successive blasting of borehole explosive charges is determined by formulas (1) - (3). To calculate the deceleration interval, the detonation characteristics of the explosive (D, ρ _s ) and the diameter of the explosive charge (d _s ) are determined using the reference literature. Physico-mechanical properties (c, ρ, ν) are usually determined at the stage of exploration by known methods. The values of Φ, μ depend on the natural fracturing of the massif and are determined by the average individual size d _e from Table 1.

Table 1 d _e , m <0.05 0.05-0.15 0.15-0.40 0.40-1.0 > 1.0 F > 12 12-10 10-8 8-6 <6 μ <0.2 0.2-0.3 0.3-0.45 0.45-0.6 > 0.6

The rock pressure in the area of the projected uprising is determined either by geophysical methods, or by the well-known formula P = ρgH (where g is the acceleration of gravity, N is the depth from the surface of the earth). The value of W - LNS for each blast hole is determined from geometric constructions (see drawing).

The height of the cavity N _p is equal to the height of the uprising or the height of the beaten section, the diameter of the cavity d _p for each blast hole is determined from geometric constructions. Substituting the numerical values of the parameters in formulas (2), (3), and then in (1), we obtain the desired delay interval between each of the successively blown wells.

Next, explosive wells are charged with the deployment of fighters with electric detonators or an SINV initiation system with predetermined deceleration intervals and produce a short-blown blast.

Example. In the 4d-701 underground leach block, a cutting riser with a total length of 25 m must be passed. First, a downward compensating guide hole 1 with a diameter of 105 mm was drilled from top to bottom and expanded with a PC-220 expander to a diameter of 220 mm (see drawing). Then, from the bottom up along the borehole, a rising 10 m long and 6 m ² cross-section passed through the borehole method. After that, two more compensation wells 2 with a diameter of 220 mm and 6 blast holes 3 with a diameter of 105 mm and a length of 15 m were drilled from top to bottom.

Next, we determined by the formulas (3), (2) and (1) the deceleration intervals sufficient to eject the rock mass from the newly formed cavities.

The physicotechnical properties of the array were previously determined by known methods and in accordance with Table 1. The rocks in the region of the uprising are represented by trachidacites, c = 4.35 · 10 ³ m / s, ρ = 2.5 · 10 ³ kg / m ³ , ν = 0.29, the average size of the units is d _е = 0.15 m, Ф = 10, μ = 0.3. The blasting is carried out with M-21 grammonite with D = 3.6 · 10 ³ m / s, ρ _B = 0.85 · 10 ³ kg / m ³ , d ₃ = 0.11 m. The rock pressure is determined by the previously given formula and equal at a depth of H = 400 m, where they produced an explosion of 9.8 · 10 ⁶ PA. The value of W and the average diameter of the cavity formed d _p for each blast hole was determined according to the drawing, made at a scale of 1:20, where 4 is the boundary of the break-off zone from each well. The measurement results of W and d _p are given in table. 2. The height of the compensation cavity N _p is equal to the height of the uprising - 15 m, the volumetric mass of the crushed rock taking into account the compensation coefficient 2 is ρ _p = 0.5 · ρ = 1.25 · 10 ³ kg / m ³ . The results of the calculation of the deceleration intervals are given in table.2.

table 2 No. of wells one' 2 ' 3 ' four' 5' 6 ' W m 0.35 0.6 0.8 0.8 0.9 0.9 d _p , m 0.6 0.9 1,2 1.4 1,6 1.8 τ _about , 10 ^-3 , s 7 16 25 25 thirty thirty τ _in , 10 ^-3 , s 110 165 220 257 294 330 τ, 10 ^-3 , s 117 181 245 282 324 360

The retardation interval in electric detonators ED-8Zh, ED-3-N and the selection of retardation steps were carried out based on the value of τ from table. 2. For explosive charges 1 ', 2', 3 ', 4', 5 ', 6', the deceleration intervals are respectively 0 ms, 120 ms, 300 ms, 500 ms, 800 ms, 1000 ms.

After that, the wells were charged with the installation of militants equipped with electric detonators ED-8ZH, ED-3-N with deceleration steps of 0, 6, 14, 18, 21, 23, and short-blown wells 1'-6 'were produced.

After the blasted rock mass was shipped from the lower part of the rebellion, it was established that the rebel 15 m long was passed to its entire height without pressing the rock mass in its contour.

Thus, it has been established that the use of predetermined deceleration intervals between successive blasting of wells ensures rock breaking from the massif, the ejection of rock from the newly formed cavity and prevents the effect of pressing in the uprising blasted rock mass. This allows you to increase the height of the section or even use sectionless blasting when driving uprising up to 30 m high, which significantly increases the technical and economic performance of the uprising and inclined mine workings.

APPENDIX

Analytical calculation of the deceleration interval necessary for the ejection of rock from the compensation cavity during the excavation of the rising mine

The process of ejection of the rock mass from the compensation cavity consists of two time steps. At the first stage, after an explosive charge explosion toward an open surface under the action of detonation products (PD) at a speed of 10-100 m / s, a wave of cracking deformations propagates, which crushes the individual rock mass and breaks it into a compensation cavity. At the second stage, gaseous detonation products (PD) act on the crushed rock mass, providing its ejection from the formed cavity. This process can be written as

where τ _about - the time required for breaking the rock from the array;

τ _in - the time required to eject the rock mass from the compensation cavity.

The value of τ _about is determined by the formula

- средняя скорость распространения волны деформаций на участке расстояния w от заряда ВВ до открытой поверхности. Согласно работе [1] средняя скорость распространения волны деформаций равнаWhere

- the average speed of propagation of the deformation wave in the distance w from the explosive charge to the open surface. According to [1], the average propagation velocity of a deformation wave is

Then

Rock mass ejection time of the formed cavity is determined based on the law of conservation of energy, whereby the energy remaining in the PD breed after ejection into the cavity (E _PD) spent on the kinetic energy of ejection of the rock mass (E _k) of the cavity, i.e.

It should be noted right away that the energy spent on overcoming the forces of gravity and friction in the rock mass is not taken into account, because in the first case, numerical calculations show that the energy to overcome the forces of gravity is 2 orders of magnitude lower than E _pd . The energy spent on overcoming friction in the rock mass during its movement is not taken into account, because in this case, the effect of “fluidization” occurs in the cavity, i.e. due to the high density of PD- (0.5-1.0) · 10 ³ kg / m, the rock mass for a certain time floats in the PD.

It's obvious that

- среднее удаление газообразных ПД в полости после взрыва очередного заряда ВВ;Where

- the average removal of gaseous PD in the cavity after the explosion of the next explosive charge;

- средний объем газообразных ПД в полости после взрыва.

- the average volume of gaseous PD in the cavity after the explosion.

и

определены как среднеарифметическое в начальной стадии (сразу после отбойки Р_п1, V_п1 и на момент, когда вся масса выброшена из полости Р_п2, V_п2).The average values of the parameters

and

defined as the arithmetic mean in the initial stage (immediately after breaking P _p1 , V _p1 and at the moment when the whole mass is ejected from the cavity P _p2 , V _p2 ).

The value of R _p1 according to [2] for elongated explosive charges is determined from the formula

where P _c is the average pressure PD in the well;

S _c , S _p1 - respectively, the cross-sectional area of the well and cavity.

Using the research data [2] from (10), we obtain

In the final stage of ejection of the mixture of rock mass and PD (GM-PD), the value of P _p2 can be taken equal to 0.

Then the average pressure PD in the cavity for the entire time of the ejection of the rock mass from it is equal to

The average volume of the cavity occupied by the rock mass-PD (GM-PD) mixture during the time the mixture is completely ejected from the cavity is obviously equal to

The kinetic energy of a moving rock mixture GM-PD is

Substituting (13), (12) in (9), and calculated and (14) in (8), we obtain the average velocity of the GM-PD mixture in the cavity

Obviously, the time required for the complete discharge of the PD-GM mixture from the cavity is

Information sources

1. Tyupin V.N. Improving the efficiency of geotechnology using the energy of the explosion during the deformation of fractured stressed massifs of rocks. - Diss. for a job. student step. Dr. tech. sciences. - Moscow, - VNIPIpromtekhnologii. 2002, p. 105.

2. Baum F.A., Stanyukovich K.P., Shekhter B.I. Explosion physics. - M .: Fizmatgiz 1959. 793 p.

Claims (1)

The method of drilling uphill with rock breakdown by borehole explosive charges, including the drilling of compensation and blast holes, loading of blast holes and their short-blown blast into compensation wells or formed cavities, characterized in that the deceleration interval between successively blasted wells is determined taking into account the need to prevent the effect of pressing mountain masses in the circuit rising from the expression

where τ _about - the time required for breaking the rock from the array, s; τ _in - the time required to eject the rock mass from the compensation cavity, C.

where W is the LNS or the distance between the explosive charge and the nearest wall of the compensation cavity, m; D — detonation velocity of explosives, m / s; ρ _in - loading density, kg / m ³ ; d _s - diameter of explosive charge, m; μ is the coefficient of friction between the elements in the array; ν is the Poisson's ratio of the individual; ρ is the bulk mass of the rock, kg / m ³ ; Ф - index of fracture massif; P is the rock pressure at the blast site, Pa; C is the velocity of the longitudinal wave individually, m / s; N _p - the height of the compensation cavity, which produce blasting, m; d _p - diameter of the compensation cavity, m; ρ _n - volumetric mass of crushed rock in the contour of the compensation cavity at the time of its release, kg / m ³ ; π = 3.14.