JPH06323797A - Blasting method - Google Patents

Abstract

PURPOSE:To obtain a well-finished, smooth, excavated surface by providing a plurality of blasting holes at specified space intervals, setting electronically delayed electric detonator caps at specified times and simultaneously effecting blasting in the blasting holes within a specified accuracy of time with regard to the set times. CONSTITUTION:In a 11-stepped blasting of a cross section of a tunnel, blasting holes H1-H14 on a tenth-step outermost circumference are spaced apart at intervals of 30-100cm. Delay times are set in an accuracy of not more than 1ms by using DS electric detonator caps for the blasting holes H1-H7 located on the left side when viewed from the side facing a cutting face and electronically delayed electric detonator caps of a high time accuracy for the other blasting holes H8-H14 on the right side. Because damages of bedrock are suppressed and a straight, smoothly finished surface is obtained, overbreak, unfixed stone removing work and hindering stone removing work in assembling supporting are reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blasting method suitable for use in, for example, a smooth blasting method in tunnel excavation or the like, or a pre-split method in finishing a ground surface of quarry or civil engineering.

[0002]

2. Description of the Related Art The blast hole is one of the elements required to finish a rock mass smoothly by blasting, such as the smooth blasting method for tunnel excavation and the pre-split method for lapping of quarry and civil engineering. Interval, perforation accuracy, resistance wire length, amount of drug, and detonator accuracy per second.

Conventionally, for these individual elements, various combinations of construction methods have been developed and implemented by trial and error.

For example, a cushion blasting method using an explosive having a diameter smaller than the blast hole diameter, a line drilling method using a large number of holes, and the like can be mentioned.

[0005]

However, in these construction methods, the number of holes is very large, which is troublesome, and
There was a problem that the effect could not be obtained sufficiently if the rock quality changed.

The object of the present invention is to pay attention to the accuracy in seconds of the detonator to be used, and replaces the conventional stepped electric detonator using a delay agent, and is composed of an electric energy storage capacitor, a delay circuit, a switching circuit and a flash electric detonator. It is an object of the present invention to provide a blasting method capable of satisfactorily smoothing an excavated surface by using the electronic delay electric detonator with high accuracy in high seconds.

[0007]

In order to achieve the above object, the present invention sets a hole interval of a plurality of blast holes in a blasting work to 30 cm to 100 cm, and stores an electric energy storage capacitor, a delay circuit, a switching circuit and a flash. An electronic delay electric detonator including an electric detonator is set at a predetermined time, and the plurality of blast holes are simultaneously fired within 1 ms at the set predetermined time.

[0008]

According to the blasting method of the present invention, the cracking direction can be controlled as compared with the conventional simultaneous blasting with a large variation in accuracy, so the rocks are not damaged and the holes are straightened.
It can be finished smoothly. Therefore, it is possible to reduce the work of over-digging, fluff (damaged area) dropping work, and hitting work at the time of supporting and assembling, and it is possible to improve the protection of rock mass and the security level, and to plan the placement concrete. Can stand accurately.

[0009]

EXAMPLES The blasting method of the present invention will be described in detail below with reference to examples.

<Example 1> As shown in FIG. 1, in a small-section tunnel T with a rock mass of fine granite and a rock mass of about 6000 m / s, which is a hard rock of fine-grained granite, which entered about 1500 m from the 550 m elevation of the A mine. Blasted smooth blasting.

The blasting pattern is as shown in FIG. 2, and 11 steps of blasting were carried out for a tunnel section having a substantially horseshoe section. The outermost peripheral blast hole H (H ₁ ~) of the 10th of the 11 stages (the numbers in the circles represent the stages)
H ₁₄ ) used a smooth blasting explosive with a hole interval of about 45 cm. The hole spacing is preferably in the range of 30 to 100 cm as in the conventional case.
Furthermore, a DS electric detonator is installed in the blast hole (H _{1 to} H ₇ ) on the left side facing the face, and an electronic delay electric detonator (2300 ms ± 1 ms) with high accuracy in the blast hole (H _{8 to} H ₁₄ ) on the right side. The delay time was set to a predetermined second within an accuracy of 1 ms per second. Regarding the electronic delay electric detonator used here, Japanese Patent Application No. 5-584 of the present applicant's prior application
No. 71 describes in detail.

In order to investigate the damaged area of the ground by the smooth blasting method using these two types of detonators, Line-A (electronic delay electric detonator side) and Line as shown in FIGS. 1 and 3 are used. -B (DS electric detonator side) 2
Sensors S _{1 to} S _n were installed on the survey line, elastic wave survey was performed, and the damaged region was measured.

Line obtained by the above elastic wave exploration
Fig. 4 (a) shows the travel time curve of -A (electronic delay electric detonator side)
Fig. 4 shows the travel time curve of Line-B (DS electric detonator side).
It shows in (b). In both figures, the impact point (Sh
Looking at the running time at a distance of 2 m from the ot point),
Line-A is about 0.4 ms, Line-B is about 0.8 ms, and Line-B side is Line-A.
The arrival time is much slower than on the side, and it is considered that the rock mass is being damaged by this amount.

Further, assuming that the damaged region around the tunnel T has a layered structure and the elastic wave velocity is higher as the layer becomes lower, the results of the surface layer removal method are shown in FIGS. 5 (a) and 5 (b). Shown in.

From the travel time curve, the Line-A side is 2
The layer structure and the Line-B side were calculated as a three-layer structure. According to this, the surface layer (first layer) on the Line-A side has a maximum thickness of about 100 mm and an elastic wave velocity V ₁ of 178.
0 m / s, while the surface layer on the Line-B side (first
Layer) has a maximum thickness of about 250 mm and an elastic wave velocity V ₁ of 1
040 m / s, and Line-B side is Line-
It can be seen that the damaged layer is thicker than the A side.

Further, on the Line-B side, the rock layer of the second layer (intermediate layer) having an elastic wave velocity V ₂ of 4560 m / s is 1
It can be seen that it exists with a thickness of around m and is considerably damaged as compared with the Line-A side. Line-B
Line-A for pain in the bedrock up to about 1 m on the side
As described above, the maximum length was about 100 mm on the side, and it was confirmed that there was a particular difference in the effect. The above results are shown in Table 1.

<Example 2> At the same tunnel site as in Example 1, a cracky rock bed having an elastic wave velocity of about 3000 m / s was selected, and the same method was used under the same other conditions. It was confirmed that the line-A side had a maximum of about 250 mm with respect to the pain of the bedrock of about 1400 mm at the maximum, and a remarkable effect was exhibited even if the quality of the bedrock changed. The results are shown in Table 1.

[0018]

[Table 1]

[0019]

EFFECTS OF THE INVENTION According to the blasting method of the present invention, the degree of pain in the bedrock is suppressed to about 10 to 18% (that is, the reduction rate is 90 to 82%) as compared with the conventional blasting method, and it is almost linear. In addition, since it can be finished to a smooth surface, it is possible to reduce overburden, fluff (damaged area) drop work, and strike work during support work assembly, and it is possible to improve the protection of rock mass and the safety surface. Moreover, it is possible to make an accurate plan for the poured concrete.

[0020]

[Brief description of drawings]

FIG. 1 is a sectional view showing a positional relationship at an experimental site.

FIG. 2 is a sectional view showing the arrangement of blast holes when the present invention is applied to a tunnel smooth blasting method.

FIG. 3 is a cross-sectional view showing a positional relationship between a survey line and a sensor when elastic wave exploration is performed using a sensor in a damaged region of the ground after blasting.

FIG. 4 is a graph showing a travel time curve obtained by elastic wave exploration.

FIG. 5 is a graph showing the results obtained by the surface removal method from the results of FIG.

Claims (1)

[Claims] 1. An electronic delay electric detonator comprising an electric energy storage capacitor, a delay circuit, a switching circuit and a flash electric detonator at a predetermined time, with a hole interval of a plurality of blast holes in blasting work set to 30 cm to 100 cm. A blasting method characterized in that the blasting holes are set and the blasting holes are simultaneously fired with an accuracy of 1 ms or less for the set predetermined time.