JPH0842999A - Blasting method for tunnel - Google Patents

Abstract

PURPOSE:To provide a blasting method for tunnel wherein a tunnel can effectively be excavated by using a charge of a reduced amount of explosive and the amount of muck produced is reduced. CONSTITUTION:A plurality of blasting holes 1-66 are drilled in a cutting face of a tunnel and are charged with explosives and priming means for igniting the explosives. Then, the priming means of three neighboring holes 1, 2, 3 are successively ignited at a specified time interval, and the priming means of the other blasting holes 4-66 neighboring the three holes 1-3 in which the priming means have already ignited are successively ignited at a specified time interval.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tunnel blasting method for efficiently carrying out tunnel excavation.

[0002]

2. Description of the Related Art In general, the efficiency of blasting largely depends on how well the free surface is used, and the blasting efficiency increases as the number of free surfaces increases.

In tunnel digging and blasting, if only the face face is a free plane blasting, the blasting is inefficient. Therefore, the efficiency is improved by first combining core blasting to form a new free surface within the face and blasting blasting in which the two free surfaces are successively expanded.

Conventionally used as core blasting are angle cuts such as V cuts and pyramid cuts, and parallel cuts such as burn cuts, large hole cuts and spiral cuts. Of these, angle cuts such as V cuts and pyramid cuts use the face as the only free surface,
Concentrate the blast hole angle at one point in the digging direction, pierce the tunnel in the digging direction in a wedge shape or pyramid shape, intensively charge the bottom of the blast hole, and push the shear toward the facet. It is important to maintain the piercing angle of the blast hole accurately and to concentrate the hole bottom at one point. Moreover, it is preferable that the detonation be simultaneous.

Parallel cuts such as burn cuts, large hole cuts, and spiral cuts are based on the fact that a blast hole is drilled in parallel with the direction of excavation. A large-diameter hole is placed, several stages of blast holes are placed in a form surrounding it, and the central hole and face are used as the free surface.
The charge for the blast hole is almost evenly distributed to the vicinity of the mouth of the blast hole, and the blast hole group closest to the hole is one hole at a time,
This is a method in which blast holes farther than that are pushed out in parallel or in steps to push the shear toward the holes, and the holes are sequentially expanded to a size where the effect as a free surface is sufficiently exerted. . In particular, spiral cut is a method in which blast holes are spirally arranged around a large-diameter hole, and cores are detonated by sequentially initiating from the side closer to the hole. Is.

[0006] On the other hand, as the conventional payment and blast, there are a winding method and a line method.

In the winding method, two free planes are formed by blasting or concentrating blast holes arranged concentrically around a free surface of a core hole formed by core blasting and cutting and widening the core hole. Blasting or blasting the Three Freedoms.

In the line system, the blasting holes formed by blasting are provided horizontally at the same height as the blasting holes and in a range slightly narrower than the lateral width of the tunnel. The blast holes arranged in parallel are further blasted or graduated in parallel to the free plane that is splayed by blasting or blasting the two free planes. It is a blast of freedom.

[0009]

In conventional tunnel excavation, MS-stage detonators and DS-stage detonators, which have a limited number of detonators and blast stages, are mainly used. You cannot blast the three free planes. In other words, blasting with two free planes is the main, and efficient blasting with three free planes is only partially performed.

Among conventional core-cutting blasts in tunnel excavation, angle cuts such as V-cut and pyramid-cut are skilled in maintaining the puncture angle of the blast hole accurately and concentrating the bottom of the blast hole at one point. However, there is a drawback in that this decrease in precision leads to a decrease in excavation efficiency. A high accuracy of simultaneous firing is required for the initiation of the cored holes, but due to environmental problems such as blasting vibration and noise, it is necessary to divide and initiate the cored holes for the purpose of limiting the amount of the simultaneous injection. If there is
You must use MS-stage or DS-stage detonators.
However, it is difficult to maintain the above-mentioned accuracy of simultaneous firing with the MS-stage detonator and the DS-stage detonator, which causes a drastic decrease in the excavation efficiency. Further, in the case of the angle cut, a relatively large amount of shear is generated, and therefore this shear needs to be crushed for carrying out, which is one of the causes for lowering the tunneling work efficiency.

Parallel cutting such as burn cutting, large hole cutting or spiral cutting is a technique suitable for increasing the length of the blast hole in recent years, and the detonation for core removal is performed one hole or two holes in sequence. Since it is carried out, it can be said that it is also a preferable method for measures against environmental problems such as blast vibration and noise. However, the detonation time interval that maximizes the tunneling efficiency should be decided according to the length of one blast, but in the conventional MS-stage detonator and DS-stage detonator, the type and number of stages are limited. , It was not able to fully meet this demand.

On the other hand, of the paying and blasting, in the winding method, when paying in an arch shape toward the center side of the tunnel by simultaneous or several blocks, blasting occurs in two free planes and an arch action occurs. This results in inefficient blasting, which has been a cause of increasing the number of blast holes and the amount of charge.

Further, the line system is a two-free plane blasting method in which the cored holes formed by the cored blasting are sequentially cut and opened, and at the stage of cutting and opening the cored holes, the portions corresponding to the corners are hard to be blasted and blasted. The number of holes and the amount of charge must be increased. Moreover, the size of the shear tends to increase, and it takes time to process the shear after blasting.

[0014]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a tunnel blasting method capable of efficiently excavating a tunnel with a smaller amount of charge by blasting three free planes over almost the entire face of the tunnel. It is in.

Another object of the present invention is to provide a tunnel blasting method capable of reducing shear.

[0016]

According to a first aspect of the present invention, a plurality of blast holes are bored in a facet of a tunnel, and an explosive and an explosive means for detonating the explosive are loaded into the blast holes. After that, a plurality of blast holes that are adjacent to each other in a straight line are sequentially blasted one by one with their blasting means with a predetermined time difference, and subsequently, the blast holes that have already been blasted, including the blast hole that has just been blasted, are adjacent The tunnel blasting method is characterized in that each of the blasting holes is sequentially detonated with their detonating means with a predetermined time difference.

According to a second aspect of the present invention, a plurality of blast holes are bored in the face of a tunnel, and explosives and detonating means for detonating the explosives are loaded into these blast holes, and then a straight line is formed. The tunnel blasting method is characterized in that three blasting holes that are not adjacent to each other are successively blasted one by one with their detonating means one by one with a predetermined time difference.

In the second embodiment of the present invention, it is preferable that the tunnel is initiated spirally from the central portion of the tunnel toward the outer peripheral edge, and in any of the embodiments, a predetermined time difference,
For example, it is preferable to sequentially initiate the ignition in any one of the range of 1 millisecond to 250 milliseconds. Further, it is effective that the detonating means is an electrical delay electric detonator, and the detoning time accuracy thereof has an accuracy of ± 1 millisecond or less with respect to the set time.

[0019]

According to the present invention, a plurality of blast holes adjacent to each other in a straight line are spread over the entire face of the face one by one with a predetermined time difference, and the blasts are sequentially initiated. Is a blast of one free surface, but the detonation of the second and subsequent blast holes adjacent to each other in a straight line is a two-free plane because a new free surface is formed by the blast holes of the blast holes before that. It is a blast.

Subsequent detonation of the blast hole is repeated three free plane blasts except for the portion corresponding to the corner of the tunnel. If the blasting holes are not aligned in a straight line, all three blasting holes after the third blasting will be blasted because one new free surface is newly added.

When a hole is formed in advance on the face of the tunnel together with the blast hole and the blasting means loaded in the blast hole adjacent to the blast hole is to be detonated, the first blast hole is detonated two times. It will be a blast of freedom.

[0022]

EXAMPLES The best mode for carrying out the tunnel blasting method according to the present invention is that the blasting holes spirally arranged with respect to the face of the tunnel are arranged one by one from the center side of the tunnel toward the corner. The detonation is carried out sequentially at the detonation interval according to the rock quality that maximizes the excavation efficiency according to the length of one blast. As a result, without reducing the efficiency of excavation,
Environmental problems such as blasting vibration and noise do not occur, and efficient excavation can be performed. Moreover, since the detonation is performed for each hole, the crushed rock becomes smaller and the workability at the time of carrying out is improved. In other words, large crushed rocks are generated as before,
It does not lower the work efficiency when carrying out.

Also, when a plurality of blasting holes that are adjacent to each other in a straight line are used, the same two free planes are blasted even though the width of the free plane is gradually cut without changing the vertical height. In parallel with the free surface, and even when expanding further, by initiating one hole at a time from the right or left, only the first hole will be an inefficient two free surface blast, but everything else It can be an efficient blast of three free planes.

As a high-speed precision detonator, it is necessary to use the versatility of setting the detonation time and the high-speed precision.
JP-B-63-53479 and JP-A-5-79797.
It is possible to use the electrical delay electric detonator disclosed in Japanese Patent Publication No.

An embodiment of the tunnel blasting method according to the present invention will be described in detail below with reference to FIG. 1 showing the front shape of the face and its sectional view taken along the line II--II in FIG.

A hole 0 having a diameter of 105 mm is formed at the center of the facet B of the tunnel A having a cross-sectional area of approximately 25 square meters and having sandstone and medium hard rock qualities (Fig. 2).
Drilled at a depth of 1.7 meters parallel to
Further, blast holes 1 to 66 having a diameter of 42 mm were drilled at a depth of 1.7 meters so as to be arranged spirally in parallel with the tunneling direction with the hole 0 as the center. And a water-containing explosive (made by Asahi Kasei Corporation:
An electric delay electric detonator (manufactured by Asahi Kasei Kogyo Co., Ltd .: E) with 300 grams of each, and the detonation time interval having the same number of steps as the number of the blast hole shifted every 25 milliseconds.
DD) was attached to 100 g of a water-containing explosive and used as a parent die. Thereafter, the electrical delay electric detonator in each blast hole 1-66 was sequentially detonated every 25 milliseconds in the order of blast holes 1-66, and a tunnel excavation length of about 1.5 meters was obtained.

On the other hand, as a comparative example by the conventional method, the front shape of the face of the tunnel is shown in FIG.
The cross-sectional structure taken along the line IV is shown in FIG. That is, blasting holes C _{01 to} C ₀₆ for core blasting by V-cut are drilled in the central portion of the facet B of the tunnel A having a cross-sectional area of about 25 square meters having the same rock type and lithology as in this embodiment. Further, 6 blocks of blasting holes 1 _{07 to} 6 ₆₁ for paying blasting of a winding method were drilled so as to surround these blasting holes C _{01 to} C ₀₆ . Then, in the blasting holes C _{01 to} C ₀₆ for coring and blasting, 400 g of the water-containing explosive and a 100 g water-containing explosive attached to the explosive detonator as a parent die were loaded, and each of the explosives for blasting was loaded. In the blast holes 1 _{07 to} 6 ₆₁ , 400 g of the water-containing explosive and 100 gram of the DS electric detonator attached to the water-containing explosive as a parent die were loaded. After that, a flash detonator was detonated at the same time, and subsequently, DS electric detonators were sequentially fired for each block, and a tunnel excavation length of about 1.5 meters was obtained.

Table 1 shows the amount of explosives consumed per cubic meter of rock, the presence or absence of poor crushing, the size of shear, the maximum scattering distance of shear, and the cutting face in the blasting method according to the present embodiment and the blasting method according to the comparative example described above. The figures show the blasting vibrations at the tunnel entrance about 50 meters away from the surface B, respectively.

[0029]

[Table 1]

As is clear from these results, the tunnel blasting method according to the present invention has an explosive consumption of 1
It can be seen that the reduction is 0%, the shear size is about 50%, the maximum shear distance is about 40%, and the blast vibration is about 75%.

[0031]

EFFECTS OF THE INVENTION According to the tunnel blasting method of the present invention, the free surface is reasonably and regularly expanded, and it is possible to further reduce the amount of explosive consumption required for excavation to the same extent as conventional tunnel blasting. In addition, the size of the shear can be reduced, loading and unloading of the shear are easy, stones are not generated, and the blasting vibration and noise can be suppressed to a very small level.

Further, since the excavation is carried out without difficulty, the final excavated surface is smooth, the looseness of the ground is suppressed to a small level, and the supporting work and materials can be reduced.

[Brief description of drawings]

FIG. 1 is a front view of a face face in an embodiment of a tunnel blasting method according to the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a front view of a face face in blasting a tunnel by a conventional method.

4 is a sectional view taken along the line IV-IV in FIG.

[Explanation of symbols] A tunnel B face face C _{01 to} C ₀₆ blast hole 0 hole 1 to 66 blast hole 1 _{07 to} 6 ₆₁ blast hole

Claims (6)

[Claims] 1. A plurality of blast holes are formed in a facet of a tunnel, and an explosive and a detonating means for detonating the explosive are loaded into the blast holes, and then a plurality of blast holes adjacent to each other in a straight line are formed. Each of these blasting means is sequentially blasted with a predetermined time lag, and subsequently, other blasting holes adjacent to the blasting hole that has already been blasted including the blasting hole that has just been detonated are designated one by one. The tunnel blasting method is characterized in that detonations are sequentially initiated with a time difference of. 2. A plurality of blast holes are bored in the facet of a tunnel, and after the explosive and the detonating means for detonating the explosive are loaded into the blast holes, three blast holes which are not aligned in a straight line are adjacent to each other. A tunnel blasting method characterized in that the blasting holes are sequentially blasted one by one with a predetermined time difference. 3. The tunnel blasting method according to claim 2, wherein the tunnel is blasted sequentially from the central portion of the tunnel toward the outer peripheral edge in a spiral shape with a predetermined time difference. 4. The predetermined time difference is in the range of 1 millisecond to 250 milliseconds.
Alternatively, the tunnel blasting method according to claim 2 or claim 3. 5. The detonating means is an electric delay electric detonator, claim 1, 2 or 3.
Tunnel blasting method described in. 6. The tunnel blasting method according to claim 4, wherein the initiation time accuracy of the initiation means has an accuracy of ± 1 millisecond or less with respect to the set time.