KR100416567B1 - Special blasting method using artificial free face - Google Patents

Abstract

PURPOSE: A special blasting method using artificial free face is provided which minimizes generation of noise and vibration caused by blasting at base rock digging spot by blasting a base rock after forming the artificial free face in four directions of blast holes having a certain diameter. CONSTITUTION: In a blasting method using artificial free face(1) for blasting a base rock by forming artificial free face in four directions of blast holes(2) having a certain diameter, the special blasting method using artificial free face is characterized in that a distance (a) from the center of the blast holes to the center of the artificial free face formed in four directions of the blast holes is 112.5 mm, 133.5 mm, 153 mm and 450 mm if diameter of the artificial free face is 75 mm, 89 mm, 102 mm and 300 mm.

Description

Special blasting method using artificial free surface {omitted}

The present invention relates to a special blasting method that minimizes the blasting noise and vibration generated in the rock excavation site.

Currently, the methods invented to minimize the occurrence of blast noise and vibration include two quartile small blasting methods (patent 0199846) and relaxed blasting (patent 0354220) on two free sides. If it is located within 20m, it is difficult to apply because it exceeds the noise / vibration tolerance (livestock: 0.1 Kine-house (RC): 0.5 Kine).

The second quartile blasting method requires two free-floating benches as blasting conditions. During rock excavation, two free-floating benches are not easily formed naturally or artificially. Rock resistance It is a method of loading the explosive which shows explosive force (ε: energy generation) less than the tensile force, and causing crack and relaxation in the rock to secondary crushing with a breaker. If the blast hole is filled with water, the water buffers the explosive force of the explosive and the water becomes plasma to intensify the co-phenomena.

The method is a method that is difficult to apply due to the amount of noise and vibration generated when the obstacle is present within 20m, and the vibration-free excavation method (Fig. 9) is used. The vibration-free excavation refers to a rock-breaker such as a vibration-free rock crusher (Patent No. 50315). This method has the disadvantage of high construction cost and low rock excavation efficiency (daily rock excavation work).

Since vibration-free excavation only forms fine cracks in the rock, breaker secondary crushing is essential and noise is a problem.

Therefore, there is a need for a method to supplement the shortcomings of the techniques such as the second quartile blasting method and the loosening blasting method and to improve the uneconomical and inefficient characteristics of the vibration-free excavation method.

In order to minimize the blasting noise and vibration for the purpose of the present invention, an artificial free surface (1) which artificially serves as a free surface around the blasting hole (2) is disposed in four directions, and a small amount of explosive (4) is lowered (6). ) Or split (7) can be placed to minimize the amount of blasting noise and vibration and to break up the rock roots (Fig. 7) or various parts (Fig. 8).

Table 1 Work Order of Special Blasting Method Using Free Oil Surface

The shock wave generated as the explosive detonates (A of FIG. 5) breaks the rock beyond the stress limit of the rock and the remaining shock waves (B, C) are transmitted to the surroundings through the medium and disappear.

The amount of energy (shock wave) generated when using a certain explosive, i.e., the amount of vibration, varies depending on the type of explosive (4), but when the allowable vibration level is fixed, the explosive amount must be adjusted according to the distance. If no measures are taken, the blasting cannot be applied within 20m according to the vibration tolerance level (Livestock: 0.1-house (RC): 0.5Kine).

This method uses the artificial free surface (1) as a measure to reduce the blasting vibration. The artificial free surface (size: Ø75-300mm or more) is arranged at a certain distance around the blast hole (2) to explode the blasting hole (2). Detonation of (4) causes the shock wave (A) of the explosive to be delivered to the artificial free surface, resulting in crushing, while the residual shock wave (B) loses the transmission medium at the discontinuous surface as large as the aperture size of the artificial free surface, weakening or weakly transmitting ( C) and collide at the point E with the shock wave of the other blasting hole.

That is, the shock wave (A) generated when using a certain explosive (4) reaches the artificial free surface (1) around the blast hole to crush the rock and lose the reflection (D) or the progressing medium and disappears, the circumference of the artificial free surface Vibration transmitted along the can minimize the remaining shock wave (vibration) transmitted to the obstacle through a mechanism, such as to meet or disappear to meet another artificial free surface of the surrounding blast hole impact shock.

Based on the principle of minimizing vibration and the standard dose calculation in the configuration and operation of the invention (Table 4), when the obstacle is located within 20 m, the explosives are placed on the lower part of the blasting hole (6) and the root cutting (Fig. 7) is performed. If the obstacle is more than 20m, the explosives are divided and arranged in accordance with the length of the blasting hole (Fig. 3) to crush the various parts (Fig. 8).

1 is a plan view showing the arrangement of the four-way artificial free surface and the blast hole

Figure 2 is a plan view showing the distance from the blast hole to the artificial free surface

Figure 3 is a cross-sectional view showing the arrangement of artificial free surface, blast hole, explosive charge, full color (divided charge)

Figure 4 is a cross-sectional view showing the lower charge and detonator schematic diagram and blasting machine

5 is a plan view showing the transmission of the shock wave after the detonation of the blast hole

Fig. 6 is a plan view showing fracture zones and crack zones on blast holes and artificial free surfaces after blasting;

7 is a cross-sectional view (crusher) showing the state of crushing after blasting the lower charge

8 is a cross-sectional view showing the fracture state after blasting divided charges

Figure 9 shows the state of crack formation after the action of halal force

Figure 10 shows the secondary breaker fracture after the force of force

(Explanation of symbols for the main parts of the drawing)

1: Artificial free surface (Ø 75-300mm or more) 2: Blasting hole (Ø 38-51mm) 3: Full color 4: Width approx.

5: primer and blaster 6: lower charge 7: splitting charge 8: crack formation zone

9: crushing (blasting) area

A: shock wave B: weakened shock wave passing through the discontinuous plane

C: weaker shock wave passing through the discontinuities

D: Shock wave reflected by discontinuous surface

The point where the weaker shock wave of E: C collides with and offsets the shock wave of another blast hole.

BM: Blasting Machine

a: Distance from the center of blast hole to the center of free artificial surface

d: Distance from the center of blast hole to artificial free surface (minimum resistance line, free surface)

Special blasting method using artificial free surface consists of artificial free surface (1) in four directions and blast hole (2) in the center, and detonation by placing explosives (4) in the lower part (6) or a certain part (7) Let's do it.

Arrangement of explosives only in the lower part of the blast hole is carried out by rock cutting (Fig. 7), which is applied when the obstacle is located within 20m, and a parting arrangement (Fig. 3) is applied when the part is more than 20m.

When explosives (4) detonate in the blasting hole (2), blasting occurs in the direction of the shortest distance (d) of the plane (free surface) contacting the atmosphere from the explosives, where the shortest distance is called the minimum resistance line and the artificial free surface In the special blasting method, the minimum resistance line is the distance d from the center of the blast hole to the artificial free surface.

Applied Explosives Technology For Construction And Mining: by Stig O Olofsson shows the blasting results according to the separation distance from the center of the blast hole to the center of the free surface. 1.5Ø cracks This results in a complete blast or connection of a ball.

Therefore, in order to smoothly crush the various parts of the rock with the root clipper (Fig. 7) and the blast hole and the artificial free surface (Fig. 8), the arrangement of a = 1.5Ø is required, so that the center of the artificial free surface is separated from the center of the blast hole of the special blasting method. The distance a is shown in Table 2 according to the diameter of the artificial free surface.

As a result of many experiments, Hauser stated, "In free surface blasting, the amount of standard blasting is proportional to the third square of the minimum resistance line." Using Equation 1, the calculation of the special blasting method is shown in Table 4. At this time, the maximum value of hard (0.57) of Table 3 was applied.

Equation 1) L = CW ³

L: Standard dose (Kg) C: Rockiness and blasting coefficient W: Minimum resistance wire length (m)

In general, in the rock excavation site where obstacles are close to each other, test blasting is carried out to calculate the dose within the range that does not damage the obstacle before the blasting work. After determining the vibration tolerance level in the range where there is no damage to the obstacles, calculate the dosage according to the separation distance accordingly.

If the test blasting is not carried out, the dosage is calculated using the blasting vibration prediction formula proposed by the US Bureau of Minerals, which is shown in Equation 2.

V: Blasting vibration prediction (cm / sec (Kine))

D: Distance from the blasting point to the place of vibration measurement (obstruction) (m)

W: Dose (Kg / delay)

Using Equation 2, the vibration tolerance level is selected as 0.1-0.5Kine and the dosage by distance is calculated.

In contrast to Tables 4 and 5, the obstacles and separation distances by the size of artificial free surface to which the special blasting method can be applied are shown in Tables 6, 7, 8 and 9.

As such, the distance to which the special blasting method can be applied varies depending on the vibration tolerance level of the obstacle and the size of the artificial free surface (1). However, the special blasting method is difficult to apply within 20m when the domestic vibration reducing blasting method is compared with Table 5. It can be applied as.

In the case of vibration-free excavation, secondary breaker crushing (Fig. 10) is essential because cracks of several mm are formed only in one direction due to the crushing force of the rock drill (Fig. 9), and roots of the rock cutting surface cannot be cut. Incidence increases

However, the special blasting method is an economical and efficient method of drastically reducing the noise of large equipment in secondary breaker crushing or rock cutting removal by root cutting of the rock to be cut (FIG. 7) and crushing of various parts (FIG. 8).

The present invention is a special blasting method using an artificial free surface to blast the rock by forming an artificial free surface in the blasting hole direction of a predetermined diameter in order to minimize the noise and vibration caused by the blasting in the rock excavation site

1. The separation distance from the blasting place to obstacles can be applied within 20m.

2. Even if the explosive is weak, it can be broken.

3. The explosive dose can be minimized as shown in Table 4.

4. It has the effect of greatly reducing the cost of rock excavation by replacing the non-economic non-vibration drilling method.

5. It replaces the inefficient vibrationless drilling method, which greatly shortens the rock drilling period.

6.2 It is effective in reducing the amount of noise by greatly breaking the breaker and breaking the noise of large equipment.

Claims (1)

In the blasting method using an artificial free surface which forms an artificial free surface in the four directions of blast holes of a predetermined diameter and blasts the rock, If the diameter of the artificial free surface is 75mm: 89mm: 102mm: 300mm: the distance (a) from the center of the blast hole to the center of the artificial free surface formed in four directions is Special blasting method using an artificial free surface, characterized in that 112.5mm: 133.5mm: 153mm: 450mm.