RU2133447C1 - Method of blasting of crumbling rocks onto open surface - Google Patents

Abstract

FIELD: blasting of crumbling rocks of any type. SUBSTANCE: the method consists in drilling of rows of holes in a strictly definite order: the rows are drilled at an angle of 30 deg to the axis of the broken block; the first row at distance W, the rest, 2W, beginning from the toe of the bench of the broken block; the distance between holes in rows shall not exceed R_r, the depth of drilling of each hole does not exceed L_hi, and the amount of charge in it does not exceed L_chi; quantities W, R_r, L_hi,L_chi are determined depending on mining-geological and mining- engineering conditions of mining operations. EFFECT: enhanced efficiency of operations due to optimum dispersion of holes in area and depth of the rock mass to be broken, as well as differentiated distribution of explosive within the block to be broken. 2 dwg

Description

 The present invention relates to the mining industry and can be used for explosive destruction of a fractured rock mass during blasting to a bare plane.

 A known method of explosive destruction of a fractured mountain massif (B. Kutuzov, V. N. Tyumin. Determination of the size of the zone of controlled crushing during the explosion of a charge in a fractured massif. Izv. VUZov. Mining Journal. 1979, N 8, pp. 30-35).

 The disadvantages of the method are the lack of consideration of the influence of the depth of drilling of wells and the magnitude of the charges in them, depending on the geological and mining conditions of mining, the direction of breaking, the non-optimality of the proposed method.

 The closest in technical essence and the achieved result is a method of destruction of a rock mass (A.P. Andrievsky. Method of explosive destruction of a fractured rock mass during blasting to a bare plane. Polar dec. Application N 95105787/03 (0105-68).

The disadvantages of the method are: does not take into account the depth of drilling and the magnitude of the charges in the wells for specific mining and geological and mining conditions; non-optimal action of the explosion and the resulting form of the collapse of the blown up rock mass in the contour of the beaten block. The aim of the invention is to increase the efficiency of explosive destruction of a fractured rock mass under various mining and geological and mining conditions, the ability to take into account the depth of drilling wells in a rock mass and the charge for specific conditions, as well as the optimal effect of the explosion. To this end, in a known method, including drilling wells in the contour of a fractured fractured massif, placing explosive charges in them and blasting them in succession, the block is drilled in such a way that the axis of the drilled block is divided into sections: the first at a distance of W, the others at 2W ( starting from the bottom edge within the contour) at an angle of 30 ^o on both sides of it, drill a series of wells at a distance (no more than this value) from each other within the contouring depth of L _squi , place explosive charges of L _zi in them and explode one by one , starting from an open surface.

The method is illustrated by drawings, where in FIG. Figures 1 and 2 show a diagram of the location of wells on the bottom area, the drilling depth and the amount of charge in them (A-A is the axis of the block; I, II, III ... are sections on the axis of the block; I, II-II ^I ... - blasting rows and blasting sequence; 1, 2, 3 ... - drilled wells).

The method is as follows: in the design contour of the beaten fractured mass in the direction of breaking, an axial line is determined (A-A, see Fig.), Which is divided into an equal number of sections, starting from the bottom edge of the block to be beaten, the first length W, the rest 2W (not more than this value); from each section on both sides of the center line at an angle of 30 ^o blasting rows are carried out, which are divided into an equal number of sections (within the contour) of length R _p (no more than this value); at each of the obtained points, the depth of well drilling (L _squi ) and the amount of charge in it (L _zi ) are _determined .

где Hyi - высота уступа в месте обуривания скважины, м;
W - линия наименьшего сопротивления, м;
W = Rp • cos3D^o;
R_p= 0,2102d•g^0,75•Д^1,5•σ $\genfrac{}{}{0ex}{}{\text{-0,5}}{\text{сж}}$ •τ $\genfrac{}{}{0ex}{}{\text{-0,5}}{\text{ср}}$ •K $\genfrac{}{}{0ex}{}{\text{-0,5}}{\text{c}}$ ;
d - диаметр заряда ВВ, м;
Д - скорость детонации применяемого ВВ, м/с;
σ_сж - предел прочности пород на сжатие, Па;
τ_ср - предел прочности пород на срез, Па;
K_c - коэффициент структурного ослабления, д.ед.;

L_т - среднее расстояние между трещинами, м;

Существо и пример конкретного выполнения способа заключается в следующем. Определяется горно-геологические и горно-технические условия отбойки трещиноватого массива; например, необходимо произвести отбойку трещиноватого массива в породах с пределом прочности на сжатие 140 МПа; предел прочности пород на срез 42 МПа; среднее расстояние между трещинами 50 см; ВВ - зерногранулит 78/21 (скорость детонации 4,2 км/с); плотность заряжания 1,1 г/см³; высота уступа 10 м; диаметр скважин 250 мм.The drilling depth and charge are determined from the relationship:

where Hyi is the height of the ledge at the place of drilling the well, m;
W is the line of least resistance, m;
W = Rp • cos3D ^o ;
R _p = 0.2102d • g ^0.75 • D ^1.5 • σ $\genfrac{}{}{0ex}{}{\text{-0.5}}{\text{squ}}$ • τ $\genfrac{}{}{0ex}{}{\text{-0.5}}{\text{wed}}$ • K $\genfrac{}{}{0ex}{}{\text{-0.5}}{\text{c}}$ ;
d is the diameter of the explosive charge, m;
D is the detonation velocity of the explosive used, m / s;
σ _SJ - tensile strength rock compressive Pa;
τ _cf is the ultimate tensile strength of the rocks, Pa;
K _c - structural attenuation coefficient, d.ed .;

L _t - average distance between cracks, m;

The essence and example of a specific implementation of the method is as follows. The mining-geological and mining-technical conditions for breaking the fractured massif are determined; for example, it is necessary to break off a fractured mass in rocks with a compressive strength of 140 MPa; ultimate tensile strength of rocks 42 MPa; average distance between cracks 50 cm; BB - granulite 78/21 (detonation velocity of 4.2 km / s); loading density 1.1 g / cm ³ ; ledge height 10 m; well diameter 250 mm.

R'_p = 0,2102 • 0,25 • 1100^0,75 • 4200^1,5(14 • 10⁷)(42 • 10⁶)⁰⁵ = 3,75 ≈ 4 м
2) Определяем виличину R_p:

3) Определяем величину W:
W = 6 • cos30^o = 4,94 ≈ 5 м
4) Определяем глубину бурения вертикальных скважин (по формуле 1):

5) Определяем длину заряда в скважине (по формуле 2);
L_з = 10,5 - 5 = 5,5 м (5,5 > 0,5 • 10,5)
Имея все необходимые данные можно приступить к обуриванию, и отбойке планируемого блока (с таким условием, что глубина бурения скважин равна 10,5, а длина заряда в скважинах 5,5 м; величина R_p = 6 м; величина W = 5 м).1) Determines the value

R ' _p = 0.2102 • 0.25 • 1100 ^0.75 • 4200 ^1.5 (14 • 10 ⁷ ) (42 • 10 ⁶ ) ⁰⁵ = 3.75 ≈ 4 m
2) Determine the value of R _p :

3) We determine the value of W:
W = 6 • cos30 ^o = 4.94 ≈ 5 m
4) Determine the drilling depth of vertical wells (according to formula 1):

5) Determine the length of the charge in the well (according to formula 2);
L _s = 10.5 - 5 = 5.5 m (5.5> 0.5 • 10.5)
Having all the necessary data, you can start drilling and breaking the planned block (with the condition that the drilling depth of the wells is 10.5 and the charge length in the wells is 5.5 m; R _p = 6 m; W = 5 m) .

 Thus, the proposed method has advantages in comparison with the prototype: it allows to ensure the stability of blasting for various mining and geological and mining conditions; to obtain the optimal drilling depth and charge in the wells, as well as to ensure the optimal action of the explosion in the destructible array.

Claims (1)

Method of explosive fracture of fractured rocks, including drilling a series of wells, placing explosive charges in them and sequential (orderly) blasting them, starting from a bare surface, characterized in that the rows of wells are drilled at an angle of 30 ^o to the axis of the block being beaten (in the direction of breaking) depth L _squi

with the placement of explosive charges of length L _zi in them:

where H _уi is the height of the step in the place of drilling the well, m;
W is the line of least resistance, m,
W = R _p • cos30 ^o ;
R _p = 0.2102d × g ^0.75 D ^1.5 × σ $\genfrac{}{}{0ex}{}{\text{-0.25}}{\text{squ}}$ × τ $\genfrac{}{}{0ex}{}{\text{-0.5}}{\text{cp}}$ × K $\genfrac{}{}{0ex}{}{\text{-0.5}}{\text{c}}$ ;
d is the diameter of the explosive charge, m;
g is the density of explosives in the charged well, kg / m ³ ;
D is the detonation velocity of the explosive used, m / s;
σ _SJ - tensile strength rock compressive Pa;
τ _cp is the ultimate tensile strength of the rocks, Pa;
K _{with the} coefficient of structural attenuation, d.ed,

L _t - average distance between cracks, m;

the distance between the rows of blasting along the axis of the block should be at least 2W (with the exception of the first, which is drilled at a distance W from the lower edge of the blasting block), and in the rows between the wells no more than R _p , starting from the lower edge of the block taking into account their placement in the design loop.

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