JP2020125653A - Mouth pipe, and method using the same - Google Patents

Abstract

To provide a mouth pipe capable of being securely held or fixed to a natural ground and securely preventing a material supplied to an underground via the mouth pipe from leaking to a ground side, and to provide a method using such a mouth pipe.SOLUTION: A mouth pipe (10) of the invention comprises: a spiral blade (12, a spiral: a screw) disposed at a main body portion (11) of the mouth pipe (10); and a plate-shaped member (13: a first plate) capable of covering the main body portion disposed at a ground side end portion of the main body portion (11). A method of this invention includes: a step of installing the mouth pipe (10) in a natural ground (G); a step of drilling a borehole (H) in the natural ground via an inner space of the mouth pipe (10); and a step of supplying a consolidation material (C: for example, cement milk) into the borehole (H).SELECTED DRAWING: Figure 11

Description

The present invention relates to a mouth pipe used for ground reinforcement using, for example, a ground anchor or a rock bolt.

In the conventional pipe used in the earth reinforced earthwork or the like (see, for example, Patent Document 1), the pipe may move in the process of boring a boring hole or the like.
Further, in the case of performing pressure injection, the injection material such as cement milk injected under pressure may leak or flow back to the ground side only with the mouth pipe.

Even in the conventional techniques using other mouth pipes, it is difficult to securely hold or fix the mouth pipe to the ground.
In addition, various conventional techniques have been proposed to prevent the injected material from leaking to the ground side. However, in the conventional technology, leakage of the material (injection material) to the ground side is sufficiently prevented without using a packer. Was difficult.

JP 2002-309573 A

The present invention has been proposed in view of the above-mentioned problems of the conventional technology, and can reliably hold or fix the mouth pipe to the ground, and the material supplied to the ground via the mouth pipe. The purpose of the present invention is to provide a mouth pipe that can reliably prevent water from leaking to the ground and a construction method using such a mouth pipe.

The mouth pipe (10) of the present invention is provided with a spiral wing (12, spiral: screw) on the main body (11) of the mouth pipe (10), and the main body ( It is characterized in that a plate-like member (13: first plate) capable of covering 11) is provided.
Here, the mouth pipe (10) of the present invention can be applied not only to the ground reinforced soil but also to the ground improvement method using piles or the like.
The lock bolt (1) to be used is not limited to a hollow lock bolt, and any type of reinforcing bar or deformed steel bar may be used.

In the mouth pipe (10) of the present invention, the spiral blade (12, spiral: screw) may be a thread.
Further, it is preferable that the spiral blade (12, spiral: screw) is fixed to the mouth tube main body (11) by welding.
Further, as the spiral blade (12, spiral: screw), a stirring screw and a conveying screw can be used.

The method of the present invention comprises a step of installing the mouth pipe (10: the mouth pipe of claim 1) in the ground (G), and a boring hole in the ground (G) through the internal space of the mouth pipe (10). It is characterized by having a step of boring (H) and a step of supplying a solidifying material (C: eg cement milk) into the boring hole (H).
Further, the method of the present invention comprises a step of boring a boring hole (H) in a ground (G), and the mouth pipe (10: the mouth pipe of claim 1) at the ground-side end of the boring hole (H). It is characterized by having a step of installing and a step of supplying a solidifying material (C: for example, cement milk) into the boring hole (H).

The method of the present invention has a step of inserting a reinforcing material (1:, for example, a lock bolt) into the boring hole (H), and a step of fixing the inserted reinforcing material (1) to the mouth pipe (10). Is preferred.
In that case, in the step of supplying the solidifying material (C) into the boring hole (H), the solidifying material (C) is injected under pressure through the reinforcing material (1) (primary injection). Is preferred.
Then, after the solidifying material (C) is pressure-injected (primarily injected) through the reinforcing material (1), the solidifying material (C) is secondarily injected through the mouth pipe (10). It is preferable to have a step of In that case, it is preferable that the solidifying material (C) is injected (secondary injection) through the mouth pipe (10) so that all the gaps in the mouth pipe (10) are filled with the solid material (C).

In the method of the present invention, the reinforcing material (1) is preferably a hollow rock bolt. Here, the reinforcing material (1) is not limited to a hollow lock bolt, and a reinforcing bar or a deformed steel bar can be applied in combination with the mouth pipe (10).
When a reinforcing material (1) other than a hollow rock bolt is used in the present invention, unlike the hollow rock bolt (there is no reinforcing bar or deformed steel bar), there is no hollow portion, so that the pressure injection (primary injection) The step of injecting is not performed through the reinforcing material (1) but is performed through the mouth pipe (10). Even in this case, the pressure of the solidifying material (C) injected through the mouth pipe (10) can be maintained.

According to the present invention having the above-described configuration, since the spiral blade (12, spiral: screw) of the mouth pipe (10) is screwed into the ground (G), the mouth pipe (10) is not ground. It is held without being pulled out (disengaged) from (G). Further, even if pressure injection is performed, the mouth pipe (10) is held without being pulled out (disengaged) from the natural ground (G) by the pressure at the time of injection.
On the other hand, even if the force of pulling the reinforcing material into the ground side acts, the spiral wing (12) of the mouth pipe (10) is screwed into the natural ground (G), so The mouth pipe (10) can be integrated to resist the pulling force.
That is, the mouth tube (10) is prevented from moving.

Further, according to the present invention, the outer surface of the spiral blade (12) provided around the mouth pipe (10) acts as a spiral labyrinth seal, so that the injection material (C) injected under pressure is injected into the mouth pipe. A situation in which the material leaks to the ground side through the outer surface of (10) is prevented, and the injection material (C) injected under pressure overflows from the outer peripheral portion of the mouth pipe (10) to the ground side (runs away). There is no.
In other words, even if a packer is not used, the injection material (C) does not overflow during the pressure injection, and the mouth pipe (10) does not come off from the natural ground (G). Therefore, according to the present invention, the packer required in the prior art is unnecessary.

According to the present invention, the pressurized state can be maintained without using a packer, and the injection liquid (C) is solidified in the expanded state while maintaining the pressurized state, and the expanded shape remains as it is. Since the fixing body can be configured, the pulling resistance is improved.
In addition, since the spiral blades (12) provided around the mouth tube (10) improve the withdrawal strength, a stronger withdrawal strength is obtained as compared with the conventional method of combining the mouth tube and the mouth packer. can get.

It is a figure showing a mouth pipe concerning an embodiment of the present invention. It is explanatory perspective view which shows the state which combined the mouth pipe and lock bolt of FIG. It is a process drawing in an example of the earth reinforcement earthwork which concerns on embodiment shown, Comprising: It is explanatory drawing which shows the state which installed the mouth pipe of FIG. FIG. 4A is a process diagram showing a step that follows the step shown in FIG. 3 and is an explanatory diagram showing a state where a boring hole has been drilled. It is a process drawing in the modification of the earth reinforced earthwork shown in Drawing 3 and Drawing 4, and is an explanatory view showing the state where a boring hole was drilled in the earth. FIG. 6 is a process diagram showing a process that follows the process shown in FIG. 5, and is an explanatory view showing a state in which a mouth pipe is installed at the ground-side end of the boring hole. FIG. 7 is a process diagram showing a process after FIG. 4 or FIG. 6 and is an explanatory view showing a state where cement milk is injected and a lock bolt is inserted. FIG. 8 is a process diagram showing a process that follows the process shown in FIG. 7, and is an explanatory diagram showing a state in which a first nut is screwed into the lock bolt. FIG. 9 is a process diagram showing a process following on from FIG. 8 and is an explanatory diagram showing a state in which a second plate is mounted on the first plate. FIG. 9 is a process diagram showing a process following FIG. 8, showing a state in which a second nut is screwed into a lock bolt, and a second plate is sandwiched and fixed by a first nut and a second nut. It is a figure. It is a flowchart showing the process of pressure-injecting cement milk from a rock bolt. It is process drawing which shows the state which closed the ground side edge part of the lock bolt after the pressure injection in FIG. FIG. 13 is a process chart showing a step that follows the step shown in FIG. 12 and is an explanatory diagram showing a state where secondary implantation is performed.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
First, a mouth pipe 10 (steel pipe with a screw) according to the embodiment will be described with reference to FIG. 1. In FIG. 1, the mouthpiece tube indicated by reference numeral 10 has a spiral blade 12 (helix: screw) formed integrally with a main body 11 made of a hollow steel tube. Here, the screw 12 may be formed in a part of the main body 11 in the axial direction, or may be formed over the entire length in the axial direction. The pitch of the screw 12 is not limited to that shown in FIG.
A circular plate-shaped member 13 (first plate) is provided at the ground-side end (right end in FIG. 1) of the main body 11, and the diameter of the first plate 13 is larger than that of the main body 11. is there. A hole 13A is formed in the center of the first plate 13, and the inner diameter of the hole 13A is substantially equal to the inner diameter of the hollow portion of the main body 11. However, the first plate 13 is not limited to the circular shape. When the first plate 13 is not circular, it has a size that can cover the main body 11.
As a method for attaching and fixing the spiral screw 12 to the main body 11, for example, there is welding. As the spiral blade forming the screw 12, a stirring screw or a conveying screw can be used or diverted.
In the illustrated embodiment, a screw thread may be processed instead of the screw 12 in the mouth tube 10.
The mouth pipe 10 according to the illustrated embodiment can be applied not only to the ground reinforcement soil but also to a ground improvement method using piles or the like.

In FIG. 2 showing a state in which the mouth pipe 10 of FIG. 1 is combined with the lock bolt 1, the lock bolt 1 penetrates the hollow portion of the main body 11 of the mouth pipe 10.
Although not clearly shown, the lock bolt 1 has a hollow portion, the hollow portion extending in the axial direction, and configured so that a solidifying material (for example, cement milk) can pass therethrough. In the outer peripheral surface of the lock bolt 1, illustrated over the entire length, or at least in the region from the tip on the ground side (right side in FIG. 2) to the position where it is screwed with the female screw of the first nut 2 (see FIG. 8 ). Not a male screw is formed.
In the area on the underground side (left side in FIG. 2) of the lock bolt 1, the preceding lock bolt 1 is connected at the joint portion having the spacer 5. FIG. 2 shows a state in which a total of three lock bolts 1 are connected.
A tip cap 6 with a spacer is provided at the tip of the lock bolt 1 on the ground side. In the step of pressure-injecting the solidifying material (cement milk) from the lock bolt 1 (described later), the cement milk is injected into the boring hole H (see FIGS. 4 to 13) via the tip cap 6 with a spacer. It

A square second plate 14 is attached to the first plate 13 of the mouth pipe 10 in the vicinity of the ground side (right side in FIG. 2) end of the mouth pipe 10. However, the shape of the second plate 14 is not limited to the square. Although the first plate 13 and the second plate 14 are attached at four locations in the illustrated example by the attachment bolts BT, the attachment mode and the number thereof are not particularly limited. Although not clearly shown, the second plate 14 is formed with a hole having an inner diameter through which the lock bolt 1 can pass, in the center thereof.
Further, in the vicinity of the ground side (right side in FIG. 2) end of the mouth pipe 10, the first nut 2 (see FIG. 8: not shown in FIG. 2) and the second nut 3 are screwed into the lock bolt 1. In addition, the first and second nuts 2 and 3 sandwich the second plate 14 therebetween, thereby fixing the second plate 14 to the lock bolt 1. In other words, the first plate 13 is fixed to the lock bolt 1 via the second plate 14, the first nut 2 and the second nut 3, so that the mouth tube 10 and the lock bolt 1 are fixed. Is fixed.
The process of fixing the mouth tube 10 and the lock bolt 1 in this way will be described later with reference to FIGS. 8 to 10.

A cap 4 is attached to the ground side end of the lock bolt 1. Cement milk injected from the upper end of the lock bolt 1 after the primary injection process (see FIG. 11) of the cement milk C (see FIGS. 7 to 13: solidifying material) by closing the upper end of the lock bolt 1 with the cap 4. Backflow, that is, so-called "pressure is released" is prevented.
In the state where the second plate 14 is attached to the first plate 13, in FIG. 2, the injection hole (see FIG. 13) for the secondary injection (see FIG. 13) is provided at the same position on the first and second plates 13 and 14. (Not shown) is formed. Although not explicitly shown, the second plate 14 is provided with a plurality of inlets, at least one for cement milk injection, the other inlet acting as an air hole. A plug 16 that closes the inlet is provided on the second plate 14. This is because by closing the secondary injection hole (not shown) with the plug 16, it is possible to prevent the injected cement milk from flowing back (pressure is released) after the secondary injection.
9 to 13 for explaining the injection process and the like, the injection hole and the plug 16 are not shown in order to avoid complexity. In other words, the plug 16 is only shown in FIG.
Although not shown, the mouth pipe 10 can be applied in combination with not only the lock bolt 1 but also a reinforcing bar or a deformed steel bar.

Next, with reference to FIGS. 3 to 13, the earth reinforced earthwork using the mouth pipe 10 (steel pipe with screw) and the lock bolt 1 shown in FIGS. 1 and 2 will be described.
In the process shown in FIG. 3, the mouth pipe 10 is installed on the natural ground G. When installing the mouth pipe 10 on the ground G, the screw 12 of the mouth pipe 10 is screwed into the ground G, and the first plate 13 of the mouth pipe 10 is brought into contact with the ground surface of the ground G. And it progresses to the process shown in FIG.
In the process shown in FIG. 4, the boring hole H is drilled in the natural ground G through the internal space of the mouth pipe 10 installed in the natural ground G. When boring the boring hole H, the boring hole 10 is bored through the inside of the mouth pipe 10 from the lower end of the mouth pipe 10 to the underground side by a predetermined distance.

5 and 6 show modifications of the embodiment shown in FIGS. 3 and 4. In the modified examples of FIGS. 5 and 6, the order of the installation process of the mouth pipe 10 on the natural ground G and the drilling process of the boring hole H shown in FIGS. 3 and 4 are reversed.
That is, the boring hole H is drilled in the natural ground G in the process of FIG. In the process of FIG. 6 executed after the process of FIG. 5, the mouth pipe 10 is screwed into the ground G at the ground-side end of the boring hole H.

After the mouth pipe 10 is installed on the natural ground G and the boring hole H is drilled by the steps of FIGS. 3 and 4 or the steps of FIGS. 5 and 6, the step shown in FIG. 7 is executed.
In the step shown in FIG. 7, first, cement milk C (solidifying material) is injected into the boring hole H. The cement milk C is injected from the ground-side end of the mouth pipe 10 (specifically, the hole 13A (FIG. 1) formed in the center of the first plate 13) through the hollow portion of the mouth pipe 10. Be seen. Illustration of the state where the cement milk C (solidifying material) is injected into the boring hole H is omitted.
After the cement milk C (solidifying material) is injected into the boring hole H, the lock bolt 1 (reinforcing material) is inserted into the boring hole H. The lock bolt 1 is inserted from the hole 13A (see FIG. 1) of the first plate 13 at the ground side end of the mouthpiece tube 10 through the hollow portion of the mouthpiece tube 10.

In the state shown in FIG. 7, cement milk C is injected into the boring hole H, and the lock bolt 1 is further inserted. In the state shown in FIG. 7, the first plate 13 of the spout pipe 10 is in contact with the surface of the natural ground G.
Since the screw 12 is screwed into the natural ground G, the mouthpiece tube 10 is held without being pulled out (disengaged) from the natural ground G. Further, since the first plate 13 is in contact with the surface of the natural ground G, even if a tensile force pulling the mouth pipe 10 to the underground side acts, it is fixed to the first plate 13 via the mouth pipe 10. Since the lock bolt 1 that is present can resist the tensile force, it does not sink to the ground side. Therefore, the mouth pipe 10 does not move.
In the process of FIG. 7, it is possible to insert the rock bolt 1 into the boring hole H at a stage before pouring the cement milk C (solidifying material) and then to inject the cement milk C into the boring hole H. .. In that case, the cement milk C can be injected into the boring hole H through the hollow space of the lock bolt 1.

Next, a process of fixing the lock bolt 1 inserted in the boring hole H to the mouth pipe 10 will be described with reference to FIGS. 8 to 10.
First, as shown in FIG. 8, the first nut 2 is screwed into the lock bolt 1. The first nut 2 is shown in dotted lines in FIGS.
When screwing the first nut 2 into the lock bolt 1, the first nut 2 is screwed into a male screw portion (not shown) at the ground-side tip of the lock bolt 1 to lock the first nut 2. A position where the first nut 2 is moved to the ground side while the bolt 1 is screwed, and the ground-side end surface of the first nut 2 and the ground-side end surface of the first plate 13 of the spout pipe 10 are substantially aligned with each other. (First nut 2) until. At a position where the ground-side end surface of the first nut 2 substantially coincides with the ground-side end surface of the first plate 13 of the spout pipe 10, the first nut 2 has a hole 13A formed at the center of the first plate 13. It is located radially inward of (FIG. 1).
In the process shown in FIG. 9, the second plate 14 is placed on the first plate 13 in the mouth tube 10 and fixed to the first plate 13. When the second plate 14 is attached to the first plate 13, for example, using mounting bolts BT and nuts (not shown), the four corners of the second plate 14 (four corners: see FIG. 2) are used. And is fixed to the first plate 13 at. However, the fixing points are not limited to the four corners.

After the second plate 14 is attached to the first plate 13, as shown in FIG. 10, the second nut 3 is screwed into the lock bolt 1 to be attached to the second nut 3 (already The second plate 14 is fixed to the lock bolt 1 by sandwiching the second plate 14 with the first nut 2 (which is screwed with).
As shown in FIG. 10, the first plate 13 and the lock bolt 1 at the tip on the ground side of the mouth pipe 10 are integrated via the second plate 14, the first nut 2 and the second nut 3, The lock bolt 1 is fixed integrally with the mouth tube 10. Therefore, when a force pulling the reinforcing member into the ground acts, in addition to the resistance force of the screw 12 of the mouth pipe 10, the first plate 13 integrally fixed to the lock bolt 1 causes It can resist the force of drawing into.
After the lock bolt 1 is fixed to the mouth tube 10 as shown in FIGS. 8 to 10, the process shown in FIG. 11 is performed.

In the step shown in FIG. 11, cement milk C is pressure-injected into the boring hole H through the hollow portion inside the lock bolt 1 by a conventionally known method (primary injection) (arrow A1).
As described above with reference to FIG. 2, the cement milk C (solidifying material) that has passed through the hollow portion of the lock bolt 1 is closed by the tip of the rock bolt 1 on the ground side (in FIG. 2, it is closed by the tip cap 6 with a spacer). Is injected into the boring hole H.
FIG. 11 shows a state in which the cement milk C is injected under pressure and the boring hole H expands outward.

At the time of pressure injection in FIG. 11, since the screw 12 of the mouth pipe 10 is screwed into the ground G, even if the cement milk C is injected under pressure, the force F acting by the pressure injection causes the mouth pipe 10 to flow. Is prevented from coming off the natural ground G, and the lock bolt 1 does not float up from the natural ground G.
Further, since the screw 12 is screwed into the ground G around the mouth pipe 10 and the outer surface of the screw 12 acts as a spiral labyrinth seal, the cement milk C injected under pressure overflows to the ground side. Is blocked. That is, the cement milk C injected under pressure does not overflow from the outer peripheral portion of the spout pipe 10 to the ground side. In other words, as shown in FIG. 11, according to the illustrated embodiment, the cement milk C (injection material) does not overflow to the ground side during pressure injection without using the packer, so the packer Is unnecessary.

When the pressure injection of the cement milk C is completed in the step shown in FIG. 11, the ground side end of the lock bolt 1 is closed by the cap 4 as shown in FIG. If the ground side end of the lock bolt 1 is not closed after pressure injection, the pressure-injected cement milk C flows back through the unclosed ground side end and flows out to the ground side. This is because it ends up in a so-called “state where pressure is released”.
In FIG. 12, part of the pressure is released after the primary injection until it is closed by the cap 4, and the boring hole H (shown by the dotted line in FIG. 12) that has expanded outward in the primary injection is the pressurized injection. It has returned to the previous state (shown by the solid line in FIG. 12).
However, since the secondary injection described later with reference to FIG. 13 is performed, the pressure is released until the ground side end of the lock bolt 1 is closed by the cap 4 after the primary injection, and the cement milk C ( Even if the solidified material) flows back to the ground side, there is no inconvenience.

After the pressure injection (primary injection) of cement milk C (solidifying material) shown in the step shown in FIG. 11 is completed and the ground side end of the lock bolt 1 is closed with the cap 4 in the step shown in FIG. As indicated by 13, secondary injection of cement milk C (solidifying material) is performed (arrow A2).
In the secondary injection of FIG. 13, as described above with reference to FIG. 2, the cement milk C is closed by the injection hole (not shown: plug 16 in FIG. 2) in the second plate 14 (and the first plate 13). (The portion in which it is present) is injected into the boring hole H through the hollow portion of the mouth pipe 10. By performing the secondary injection, the inside of the boring hole H is pressurized, and the boring hole H expands outward again.
When the secondary injection is completed, the injection hole for the secondary injection is closed by the plug 16 (see FIG. 2) so that the injected cement milk C does not flow back and flow out (the pressure is not released).
Although not clearly shown in the drawing, after the secondary injection is completed, the secondary injected cement milk should not be released from the pressure before the secondary injection hole is closed by the plug 16 before the secondary injection is completed. The secondary injection hose (not shown) connected to the injection hole (not shown) is bent to maintain the pressurized state in the boring hole H.
Although not shown, the cement injected secondarily before the step of closing the hole for secondary injection with the plug 16 by providing a device with a check valve (nipple etc.) and a valve (ball valve etc.) It can be configured so that the milk pressure is not relieved.

According to the illustrated embodiment, since the screw 12 of the mouth pipe 10 is screwed into the ground G, even if the moving mass of the plate 13 or the lock bolt 1 presses the plate 13 or the lock bolt 1 by the proof stress improved by the screw 12. 10 is held without being pulled out (disengaged) from the natural ground G. Further, even if pressure injection is performed, the mouth pipe 10 is pulled out (disengaged) from the ground G by the pressure F (FIG. 11: force pushing the mouth pipe 10 out of the ground G) at the time of injection. Retained without.
On the other hand, even if the force of pulling the reinforcing member or the like into the ground acts, the natural ground G and the mouth pipe 10 can be integrated to resist the pull-in force. More specifically, even if the force of pulling the reinforcing member or the like toward the ground side acts, the first plate 13 of the mouth pipe 10 can resist the pulling of the mouth pipe 10 to the ground side. I can. Further, since the screw 12 of the mouthpiece tube 10 is screwed into the ground G, the screw 12 can resist the mouthpiece tube 10 being pulled into the ground.
Here, since the mouth pipe 10 and the lock bolt 1 are integrated and fixed via the first plate 13, the second plate 14, the first nut 2 and the second nut 3, the mouth pipe is It is possible to prevent 10 from being pulled into the ground side.

Further, according to the illustrated embodiment, since the screw 12 (spiral blade) of the mouth pipe 10 acts as a kind of labyrinth seal, the cement milk C (injecting material) injected under pressure is the outer circumference of the mouth pipe 10. It is prevented that the part leaks or overflows to the ground side.
Therefore, according to the illustrated embodiment, the cement milk C does not overflow to the ground side during pressure injection without using a packer. That is, according to the illustrated embodiment, it is possible to omit the packer required in the related art.

According to the illustrated embodiment, the pressurized state can be maintained without the use of a packer, and the expanded cement milk C (see FIG. 13) solidifies to form the expanded body with the expanded shape. The pulling resistance is improved.
In addition to that, as described above, the screw 12 improves the withdrawal proof strength. Therefore, compared with the conventional method of combining the mouth tube and the mouth packer, a stronger withdrawal proof strength is obtained against the force of pulling out the lock bolt. Can be earned.
Further, according to the illustrated embodiment, after the primary injection is performed and the ground-side end of the lock bolt 1 is closed by the cap 4, the secondary injection is performed. Therefore, after the primary injection, the ground-side end of the lock bolt 1 is performed. Even if the cement milk C (solidifying material) flows backward until the part is closed with the cap 4, and the pressure is released, the cement milk C that has flowed back by the secondary injection and the released pressure are recovered. You can

In the illustrated embodiment, when a reinforcing material other than the hollow lock bolt is used, unlike the lock bolt, for example, a reinforcing bar or a deformed steel bar does not have a hollow portion. Therefore, pressure injection (primary injection) is not performed via the hollow portion in the reinforcing member, but pressure injection (primary injection) is performed via the mouth tube 10. Also in this case, the mouth pipe 10 is provided with an injection hole for cement milk C (solidifying material) and a plug for closing the injection hole, so that the pressure of the injected cement milk C (solidifying material) can be maintained. is there.

It should be noted that the illustrated embodiment is merely an example and does not limit the technical scope of the present invention.
For example, in the illustrated embodiment, the earth reinforced earthwork using rock bolts and the method of performing the primary injection and the secondary injection are described, but the mouth pipe of the present invention can be used even with other methods. It is noted that it is applicable and that the method of the present invention is applicable.

1... Rock bolt (reinforcing material)
10...Port pipe (steel pipe with screw)
11...Main body 12...Screw (spiral blade)
13... First plate C... Cement milk (solidifying material)
G... Ground H... Boring hole

Claims (6)

A mouthpiece characterized in that a spiral wing is provided on the main body, and a large-diameter plate-like member capable of covering the main body is provided at the ground-side end of the main body. A step of installing the mouth pipe of claim 1 in the ground, a step of boring a boring hole in the ground through the internal space of the mouth pipe, and a step of supplying a solidifying material into the boring hole. Characteristic construction method. It has a step of drilling a boring hole in the natural ground, a step of installing the mouth pipe of claim 1 at the ground side end of the boring hole, and a step of supplying a solidifying material into the boring hole. Construction method. The method according to claim 2, further comprising a step of inserting a reinforcing material into the boring hole, and a step of fixing the inserted reinforcing material to the mouth pipe. The method according to claim 4, wherein in the step of supplying the solidifying material into the boring hole, the solidifying material is injected under pressure through the reinforcing material. The method according to claim 5, further comprising a step of secondarily injecting the solidifying material through the mouth pipe after the solidifying material is pressure-injected through the reinforcing material.

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