KR102228560B1 - Method for rock cutting and tunnel excavation using shaped charge and wire saw - Google Patents

Abstract

The present invention relates to a rock cutting method using a wire saw and a tunnel excavation method. According to the present invention, a connection hole for connecting drilled holes to each other is drilled at a common bottom of the drilled holes after drilling a plurality of drilled holes in the rock. A shaped charge can be used for drilling the connection hole. When the connection hole is formed, a wire saw can be inserted into the drilled holes and the connection hole in a loop-type, and the wire saw is driven to cut a rock block between the drilled holes so as to form a line groove. In a state where side surfaces are separated from a parent rock except for a rear surface of the rock block through the line grooves, the rear surface of the rock block can be easily separated from the parent rock using gunpowder or wedges. Also, a cavity is formed by cutting the rock by repeatedly applying the aforementioned method, and further, tunnel excavation can be performed. Accordingly, the excavation speed and efficiency are improved.

Description

Rock cutting method and tunnel excavation method using molding explosives and wire saw {METHOD FOR ROCK CUTTING AND TUNNEL EXCAVATION USING SHAPED CHARGE AND WIRE SAW}

The present invention relates to a civil engineering construction technology, in particular, to a tunnel excavation method, and more particularly, to a technology for cutting the rock mass in a state where one surface is exposed, such as the curtain surface of the tunnel.

Most of the excavation of tunnels is through blasting of gunpowder. However, since blasting always involves noise and vibration, physical or social problems are often caused by this. In particular, blasting for tunnel construction in urban areas, such as subway construction, should be approached carefully due to the safety problem of surrounding facilities. In addition, there is a problem in that blasting is not easy because civil complaints related to noise and vibration must be addressed even if there is no impact on the safety of nearby facilities. Although the TBM method has been recently applied, it has not yet been widely used in Korea.

Meanwhile, research is being conducted to apply a wire saw, which was previously used for cutting stone, to the curtain surface. A conventional tunnel excavation method using a wire saw is shown in FIGS. 1 and 2. 1 is a schematic front view of a tunnel surface in which two rock drilling holes are formed, and FIG. 2 is a schematic cross-sectional view taken along line A-A of FIG. 1.

Referring to the drawing, in the conventional tunnel excavation method using a wire saw, first drill two rocking holes (A and B), then hang a wire saw (WS) on a rod (S) with a pulley (P), and With (S) inserted into the rock drill holes (A,B), turn the drive wheel (DW) to rotate the wire saw to cut the rock (R) between the two rock drill holes. In this method, when the driving wheel DW retreats and pulls the wire saw WS, a thrust must be continuously applied to the rod so that the rod S is not pulled out of the drilling hole.

In addition, in this method, the wire saw (WS) is not arranged in an elliptical shape suitable for high-speed rotation, and the shape is severely curved. In other words, in Fig. 2, the traveling direction of the wire saw (WS) in the pulley section (C,D) and the tool part (E,F) of the two rocking holes in Fig. 2 continuously changes rapidly in 180° and 90°, so the overall wire saw ( WS) may not rotate smoothly. Accordingly, a method of cutting rock mass using a pulley and a rod as shown in FIG. 2 after drilling two rocking holes in the membrane surface is expected to have many difficulties in practical application.

The present invention is to solve the above problems, and provides a rock cutting method and a tunnel excavation method with improved excavation speed and efficiency while using simple equipment, as well as advantageous application in urban areas as vibration and noise caused by blasting are minimized. It has its purpose.

Meanwhile, other objects that are not specified of the present invention will be additionally considered within a range that can be easily deduced from the detailed description and effects thereof below.

The rock cutting method according to the present invention for achieving the above object comprises the steps of: (a) drilling a plurality of rock drilling holes spaced apart from each other on one surface of the rock mass; (b) installing a molding explosive in one of the plurality of rocking holes, and then blasting toward the other side of the rocking hole to drill a connection hole between the plurality of rocking holes; (c) inserting a wire saw from one side of the rocking hole through the connection hole to the other side of the rocking hole, and connecting both ends of the wire saw to the driving wheel; And (d) rotating the wire saw to cut the rock mass between the plurality of rock drilling holes.

According to the present invention, it is preferable that the distance between the two adjacent drilling holes, that is, the length of drilling the connection hole, is approximately 30 cm or more.

In an example of the present invention, the process of inserting the wire saw into the drilling hole and the connection hole includes first inserting a connection string made of a flexible material from the drilling hole on one side to the drilling hole on the other side, and at one end of the connection string. Replacing the connection string by tying a mounting string made of rigid material and pulling it from the other end to insert the mounting string into the drilling holes and the connection hole, and connecting the wire saw to one end of the mounting string and at the other end. And a step of pulling and inserting the wire saw into the drilling holes and the connection holes.

Particularly, in a state in which the connecting strap is inserted into one side of the rock drilling hole, the connecting strap is pulled out from the rock drilling hole of the other side to the rock drilling hole of the other side through a vacuum suction device. To this end, the connecting strap is a twine, and the mounting strap uses a piano wire.

In an example of the present invention, when three or more rocking holes are arranged side by side, the connecting straps are installed in each of the two adjacent rocking holes, and the connecting straps are replaced with the mounting straps, so that the three rocking holes are arranged side by side. After making the two mounting straps connected from the adjacent rocking holes on each side fit together in the rocking hole arranged in the middle of the ball, the two mounting straps are interconnected and pulled from both sides so that the mounting strap is one of the three rock drill holes. After making the connection through the outer two rocking holes, the wire saw is installed.

In the tunnel excavation method for achieving the object of the present invention, after forming a plurality of rock drilling holes along the cross-sectional shape of the tunnel on the surface of the tunnel, the above-described rock cutting method is repeatedly performed to excavate the rock mass. It is characterized by forming part or all.

Another tunnel excavation method for achieving the object of the present invention includes the steps of: (a) drilling a long hole in the membrane surface of the tunnel; (b) performing the rock cutting method of the above configuration to cut the rock around the long hole to form at least one line groove around the long hole to form a similar free surface; And (c) charging and blasting gunpowder in the charging hole to excavate rock mass. In particular, the long yak hole is a core hole, and after forming a similar free surface by rock cutting, the core can be easily removed through blasting.

In the present invention, there is an important technical feature in that the rock is cut using a wire saw, and in particular, a connecting hole is formed by drilling between two rock drilling holes using a molding explosive. That is, in the present invention, since a connecting hole for interconnecting the cobots of a plurality of rock drilling holes is made, the wire saw can be arranged in a simple loop shape, unlike the conventional bar, the rotation of the wire saw is made smoothly, and rock cutting is performed. There is an advantage that it can be performed effectively.

In addition, since a pulley or a rod is not used like a method using a conventional wire saw, the facility is simplified, so it is much more economical and has the advantage of being able to perform the process simply.

On the other hand, even if it is an effect not explicitly mentioned herein, it is added that the effect described in the following specification and its provisional effect expected by the technical features of the present invention are treated as described in the specification of the present invention.

1 is a schematic front view of a tunnel face in which two rock drilling holes are formed.
FIG. 2 is a schematic cross-sectional view taken along line AA in a state in which a wire saw is installed in the rock drill hole of FIG. 1.
3 is a schematic flowchart of a rock cutting method according to the present invention.
4 is a schematic front view (top) and a cross-sectional view (bottom) for explaining the formation of a rock drill.
5 and 6 are views for explaining the arrangement of various types of drilling holes.
7 to 9 are views for explaining a process of forming a connection hole.
10 to 12 are views for explaining the process of installing the twine in the drilling hole and the connection hole.
13 and 14 are views for explaining a process of replacing a string with a piano wire.
15 to 17 are for explaining a process of connecting the piano wire to the driving wheel after replacing the wire saw.
18 is for explaining a form in which the line groove formation is extended and applied.
19 is for explaining a method of excavating a tunnel using a rock cutting method.
20 is for explaining an example in which the rock cutting method is applied to the core subtraction.
※ The accompanying drawings are exemplified by reference for understanding the technical idea of the present invention, and the scope of the present invention is not limited thereto.

In describing the present invention, when it is determined that the subject matter of the present invention may be unnecessarily obscured as matters obvious to those skilled in the art with respect to known functions related to the present invention, a detailed description thereof will be omitted.

The present invention relates to a rock cutting method and a tunnel excavation method in which the method is applied to a tunnel surface. The present invention can be applied to all rock cutting, including the curtain surface of tunnels and tunnels, the walls and floors of storage cavities, the floors of open-air quarry or quarry, benches and benches, and outcrops of natural rock. . In particular, it is most effective in excavating rock mass when only one side of the rock mass is exposed to the outside, such as the curtain surface of a tunnel.

Although the present invention can cut and excavate rock mass by forming a plurality of row grooves in rock mass using a wire saw, it does not exclude a method by blasting. In another invention using rock cutting, it is revealed in advance that blasting and rock cutting can be used in combination.

Hereinafter, a rock cutting method and a tunnel excavation method will be described in more detail by taking the curtain surface of the tunnel as an example.

Referring to Figure 3, the rock cutting method according to the present invention is (a) drill drilling, (b) connection hole drilling, (c) wire saw installation, (d) file groove cutting and (e) five steps of cutting rock separation Go through the procedure. That is, through the procedures of (a) to (d), a plurality of line grooves is formed in the rock mass. When viewed from the outside, the line groove is formed in the form of a polygonal or closed curve in the front of the rock mass. And the back of the uncut rock mass is separated from the parent rock through the above (e) process. Each step will be described with reference to the drawings.

1. The step of drilling the rock drill

FIG. 4 is a schematic front view of the tunnel face at the top, and a schematic cross-sectional view taken along line B-B of the top front view at the top for explaining the step of drilling a rock drill.

The rocking hole cuts the rock mass by forming a line groove connected in a closed curve or polygonal shape on the surface of the curtain. The most basic configuration or method for this is to form a joule groove using two drilling holes and a connecting hole connecting them. That is, as shown in FIG. 4, two drilling holes (1, 2) are drilled in the rock (R) by using a rock drill on the tunnel surface (T). If necessary, three or more rocking holes 1, 2, and 3 are drilled as shown in FIG. 5.

On the other hand, the outline connecting the plurality of rock drill holes does not necessarily have to be a straight line as shown in Figs. 4 and 5, and if necessary, several long and short straight lines may be arranged in various places on the rock surface, and several straight lines can be arranged with each other. It can also be connected and arranged in the form of a polygon such as a triangle or a square. As an example, FIG. 6 is a front view in which a total of 7 rock drilling holes (1 to 7) are arranged along the contour of a digut-shaped made of three straight lines.

In order to excavate a tunnel, it is common to form a drilling hole for the entire cross section of the tunnel. That is, the drilling holes must be formed along the outline of the tunnel, and since rock mass cannot be cut at once, a plurality of drilling holes must be formed in a matrix form inside the cross section. The drilling depth of the drilling hole varies depending on the situation, but it can be formed to be approximately 1 m or more, and the interval between the drilling holes is formed in the range of 30 to 500 cm. If it is less than 30cm, it is not economical because too many drilling holes have to be drilled. It can be 500cm or more, but it can vary depending on the performance of the explosive, and the longer it is, the more advantageous it is.

2. Step of drilling the joint hole

As described above, the present invention is basically composed of two drilling holes and one connecting hole, wherein the connection hole refers to a hole connecting the two drilling holes at the bottom. In the present invention, drilling of the connecting hole is performed as follows.

7 is a view for explaining the connection hole perforation. As shown in FIG. 7, a connection hole must be formed by penetrating the rock R between the two rocking holes at the bottom of the two rocking holes 1 and 2. To this end, a conical or hemispherical molding explosive (SC) is loaded in the rocking hole (1) of one side toward the rocking hole (2) of the other side. The loaded molding explosive (SC) is detonated with a detonator and penetrates between the two drilling holes (1, 2) to form a connection hole (10) as shown in FIG. 8. As shown in FIG. 9, a plurality of rocking holes may be formed and the connecting hole drilling step may be repeatedly performed to simultaneously or sequentially form the connection holes 10 and 11 between the plurality of rocking holes. As mentioned in the previous drilling hole formation step, in order to excavate a tunnel, a plurality of drilling holes must be formed in a matrix form not only along the outer contour of the tunnel section, but also inside the tunnel. Optionally or in all, connecting holes can be formed.

3. Step of inserting wire saw

After all necessary drilling holes and connection holes are drilled, the wire saw is inserted using these drilled holes. Inserting the wire saw can be done in various ways, and in this example, (i) inserting the connecting strap, (ii) inserting the mounting strap, and (iii) inserting the wire saw.

The tie-up operation is always carried out with two rock drills in a pair. As shown in Fig. 10, in a state where one end of a flexible material connection string (W, in this example, a twine) is pushed to the bottom of the rocking hole 1 on one side, and into the rocking hole 2 on the other side of the vacuum aspirator. When sucked in with the intake pipe inserted, the connection string (W) is drawn out to the other side of the rocking hole (2) through the rocking hole (1) and the connection hole (10) on one side. In the present embodiment, a twine is used as the connection string, but a flexible string, such as a thread, made of various materials that can be sucked by vacuum pressure may be used.

On the other hand, as shown in FIG. 11, if there are 3 rocking holes, first perform the threading operation of the rocking hole (1)-connecting hole (10)-rocking hole (2), and then continue to the rocking hole (2)-connecting hole. (11)-Repeat the threading operation for the rocking hole (3).

Since the above-described threading operation is always performed with two rocking holes as a pair, it does not cause any problem even if the number of rocking holes increases. For example, in the case of four rocking holes, the threading operation is sequentially repeated for the two rocking holes, and as shown in FIG. 12, three twine (W1) in the four rocking holes (1 to 4) , W2, W3) are all inserted.

After the connecting strap is inserted, the task of replacing the connecting strap with a mounting strap is performed. In this example, a piano wire or wire rope is used as the mounting string. The mounting string is for final installation of the wire saw, which will be described later, and a piano wire is used because it must have rigidity in order to connect the steel wire saw.

First, tie a piano wire to one end of each string and pull the other end of the string. Then, all the strings are discharged from the drilling hole, and only the piano wire remains in the drilling hole and the connecting hole. Even if the string is replaced with a piano wire, the appearance of the string is the same as that of the previous string. On the other hand, when a piano wire is installed in three or more rock drill holes, two rows of piano wire always pass through the rock drill hole arranged in the middle, for example, the drill hole 2 in FIG. 11 and the drill hole 2 and 3 in FIG. 12. It is done. Therefore, when the ends of the two rows of piano wires passing through the middle hole are made into one row and then pulled from both sides, it is as shown in FIGS. 13 and 14. That is, a row of piano wires (pw) is connected in a row to the drilling holes and the connecting holes disposed at both ends of the plurality of drilling holes.

Finally, put the wire saw. When the piano wire is inserted through the above two steps, a wire saw is finally tied at one end of the piano wire, and then the piano wire is replaced with a wire saw by pulling the opposite end of the piano wire. This process is the same as replacing a string with a piano wire. In this way, even if the piano wire is replaced with a wire saw, the appearance of the piano wire does not change, so the piano wire pw in FIGS. 13 and 14 may be regarded as a wire saw.

4. Step of cutting the file groove

After installing the wire saw in the rock drill hole and the connecting hole, as shown in FIGS. 15 to 17, the wire saw is connected to the driving wheel (DW) after fastening both ends of the wire saw (ws) in the form of a loop. You will be able to make a meeting. When the drive wheel (DW) is rotated, the wire saw rotates and cuts the rock (R). That is, when the driving wheel DW and the wire saw start to cut the rock R, they move backward and continue to rotate, thereby completely cutting the rock R between the two rocking holes. The driving wheel (DW) equipment is appropriately modified from the existing equipment used in standard stone quarrying, but if it is loaded and used in a truck, it is highly mobile and can be used conveniently in tunnels or mine sites.

On the other hand, when cutting the joule groove in the case where the rock drill hole is formed along a complex outline as shown in FIG. 6, the rock drill holes arranged along a single straight line are treated as a group, and the wire saw is connected and cut for each group. For example, in the case of cutting a diguin-shaped file groove in FIG. 6, a rock drill hole (1, 2) is treated as a set and cut, and the rock drill hole (2, 3, 4) is treated as a set, and a wire as shown in FIG. The saw is connected and cut, and the rock rock is cut as shown in FIG. 17 by treating the rock drill holes (4, 5, 6, 7) as a pair. In this way, when there are many rock drill holes, if you group the rock drill holes arranged in a straight line into a group, divide the whole into several groups, and then cut each group, you will be able to easily cut various types of file grooves on the rock surface.

5. Cavity formation step (cutting rock separation)

As with the cutting of several row grooves in the rock according to the above procedure, it will be possible to cut a row groove h having a rectangular outline as shown in FIG. 18. In this case, the rock block (R) inside the square formed with a total of 4 row grooves (h) has 5 free surfaces (1 free surface in the front and 4 similar free surfaces in the top, bottom, left and right (formed by the line groove)). Since it is in a state, it will be possible to easily remove the rock inside the square by making one or two perforations in the center of this rock block and blasting with only a small amount of explosives loaded. This is because the difference in the effect of blasting is very large between the case with and without the pseudo free surface.

In addition, when the cross-sectional area of the rock block R is small as shown in FIG. 18, even if an explosive is not used, simple hand tools such as a chisel and a hammer, or the physical force of equipment such as a hydraulic wedge and a breaker can sufficiently remove the rock inside the square. will be. That is, in the hexahedral rock block (R), the front and four sides (row grooves) are all incisions, and only the back is attached to the rock, so the rock block can be removed with a wedge or the like without blasting. That is, after all the line grooves are formed by rock cutting, the rock blocks may be blasted or dropped out using a wedge or the like to excavate the rock.

If the various configurations of the present invention are ideally implemented regardless of the conditions of perforation or molding explosives, it will be possible to cut grooves or cavities having various sizes and shapes on a flat rock surface to a desired depth. However, the depth of the groove that can be cut at one time in the actual field will be determined by the depth and precision (deflection) of the drilling, and the maximum separation distance between the two adjacent drilling holes will be determined by the power of the molding explosives. Therefore, the efficiency of the present invention will also depend on the quality of the perforation and the performance of the molding explosives, but within the limits allowed by these conditions, it is possible to easily cut the groove in the desired size, shape and depth on the rock surface.

If the square rock block (R) in FIG. 18 is used as a hollow cavity for tunnel blasting, the effect of vibration noise can be reduced by applying the present invention to the tunnel blasting method. For example, only the core removal hole can be performed by using a rock cutting method by forming a line groove, and after the core removal, it can be performed through a normal blasting operation. Alternatively, the tunnel can be excavated using a minimum amount of gunpowder after forming all the grooves over the entire section of the tunnel. Alternatively, the tunnel can be excavated only by rock cutting without blasting at all. That is, in consideration of the conditions and economics of the field, it is expected that the formation and blasting of the joule groove according to the present invention can be applied selectively or together.

The form of excavating the tunnel only by rock cutting is shown in FIG. 19. In other words, it can be used to excavate each rock block (R1~R12) by wire saw cutting method by dividing part or all of the excavation surface into a checkerboard shape.

In addition, a form in which the straight line groove is disposed on the tunnel face to perform blasting is shown in FIG. 20. In FIG. 20, the two rows of row grooves (A and A') cut in the center of the curtain serve as a similar free surface for each of the four core drain holes (E1 to E4). Each long hole (E1 to E4) is a blasting condition with three free surfaces (1 free surface in the front and A surface similar to free surface A and A’ surfaces), so the efficiency of core extraction can be improved and ground vibration can be reduced. Such a shim pulling pattern can be extended to various shim pulling patterns according to the appropriate arrangement of several row grooves, long hole, and armed weak hole.

The rock cutting method using a wire saw according to the present invention looks similar to the method using a conventional wire saw shown in Figs. 1 and 2, but there is a very large difference in practice. That is, in the method using the wire saw of Fig. 2, the connection hole is not formed between the drilling holes. Therefore, the wire saw (WS) must be arranged to overlap each other in the same rocking hole by using the pulley (P) and the rod (S). If the wire saw is rotated in this state, it is not easy to proceed with the rotation of the wire saw in the section (C, D, E, F) where the direction is rapidly changed. In particular, since a large compressive force acts on the pulley P of the co-bottom section (C,D), abrasion of the pulley occurs and the cutting process is not substantially smooth.

In practice, the cutting process is not smooth. In addition, since the rod (s) must be pushed with thrust, a suitable facility is required. In the present invention, there is an important technical feature in forming a connection hole by drilling between two rocking holes using a molding explosive. In the present invention, since the connection hole is made, the wire saw (WS) can be arranged in a loop type (preferably elliptical) that does not overlap each other, and the rotation of the wire saw can be made smoothly. Since this is the same as cutting rocks to specifications using a wire saw in an existing quarry, it can be seen that the technical verification has already been completed. That is, in the present invention, a wire saw is used, but by forming a connection hole between the drilling holes at the bottom of the drilling hole, rock cutting is facilitated by arranging the wire saw in a simple loop shape. In addition, since it does not use a pulley or a rod as shown in FIG. 2, the facility is also simplified, so it is much more economical and has the advantage of being able to perform the process simply.

On the other hand, in this embodiment, the wire saw is described and illustrated as using a connection string and a mounting string to install the wire saw in the drilling hole and the connection hole, but is not necessarily limited to this method, and finally, the wire saw consists of two rock drilling holes and the two It just needs to be inserted into the connecting hole that connects the drilling holes. When a plurality of rock drill holes are arranged in a row, the method is not limited if a wire saw is installed in the outermost rock drill hole and the connecting hole connecting them. For example, a robot equipped with a caterpillar capable of passing through rough pipes, or a spherical roller connected to the front end of a wire saw, may be connected from one side to the other side of the rock drill. It should be noted that wire saws can be installed in various ways. In addition, even in the case of using the same method as in this embodiment, it should be noted that various wires other than the string and the piano wire can be used as the connecting string and the mounting string.

In addition, until now, it has been described and illustrated that a molding explosive is used when forming a connection hole between the rock drilling holes, but the present invention does not exclude drilling the connection hole in various ways, such as using a special propellant or a drill other than the molding explosive. .

The scope of protection of the present invention is not limited to the description and expression of the embodiments explicitly described above. In addition, it is added once again that the scope of protection of the present invention may not be limited due to obvious changes or substitutions in the technical field to which the present invention pertains.

R ... rock block (rock), W ... twine
pw ... piano wire, WS ... wire saw
T ... close face, DW ... drive wheel
h ... line groove

Claims (10)

(a) drilling a plurality of rock drilling holes spaced apart from each other on one surface of the rock mass;
(b) drilling a connection hole between the plurality of rocking holes from the bottom of one of the plurality of rocking holes to the bottom of the other side of the rocking hole;
(c) inserting a wire saw from one side of the rocking hole through the connection hole to the other side of the rocking hole, and connecting both ends of the wire saw to the driving wheel; And
(d) rotating the wire saw to cut the rock mass between the plurality of rock drilling holes; and,
The drilling of the connection hole is performed by installing a molding explosive in one of the plurality of rocking holes, and then blasting it toward the other side of the rocking hole. delete The method of claim 1,
Rock cutting method, characterized in that the distance between the two adjacent drilling holes is 30cm or more. The method of claim 1,
First inserting a flexible material connection string from the rocking hole on one side to the rock drilling hole on the other side,
Replacing the connection string by tying a mounting string made of a rigid material to one end of the connection string and pulling it from the other end to insert the mounting string into the drilling holes and the connection hole; and
A rock cutting method, characterized in that connecting the wire saw to one end of the mounting string and pulling from the other end to insert the wire saw into the drilling holes and the connecting hole. The method of claim 4,
A rock cutting method, characterized in that, in a state in which the connecting strap is inserted into one side of the rock drilling hole, the connecting strap is pulled out from the rock drilling hole of the other side to the rock drilling hole of the other side through a vacuum suction device. The method of claim 4,
The connecting string is a twine, and the mounting string is a rock cutting method, characterized in that the piano wire. The method of claim 4,
When three or more drilling holes are arranged side by side, the connection strings are installed in each of the two adjacent drilling holes, and the connection strings are replaced with the mounting strings, and the three drilling holes are arranged in the middle of the drilling holes. Two mounting strings connected from adjacent rocking holes on each side of the ball are fitted together, and then the two mounting straps are interconnected and pulled from both sides to make the two rocking holes of the outer periphery of the three rocking holes. After making the connection through, rock cutting method, characterized in that to install the wire saw. After forming a plurality of drilling holes along the cross-sectional shape of the tunnel on the curtain surface of the tunnel,
After repeatedly performing the method according to any one of claims 1 to 7 to create a closed curve or a closed polygonal line groove on the curtain surface, a part or all of the tunnel section is excavated by removing rocks inside the groove. How to excavate a tunnel. (a) punching a long hole in the membrane surface of the tunnel;
(b) performing the method according to any one of claims 1 to 7 to cut rock mass around the long hole to form at least one line groove around the long hole to form a similar free surface; And
(c) a tunnel excavation method comprising the step of excavating rock mass by charging and blasting gunpowder in the charging hole. The method of claim 9,
The long yak hole is a hole to remove the core, a tunnel excavation method, characterized in that performing the core removal through blasting.

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