JP2000027577A - Ground drilling apparatus and intermediary double pipe therefor, and ground drilling method using those - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a time required for construction by a method wherein flushing water including slime is satisfactorily discharged without regard to the diameter and the full length of an insertion bore with an inexpensive outer casing employed. SOLUTION: For the ground drilling apparatus, a drilling double pipe C is connected to a rock drill 11 through a connector B that transmits a rotatory power only to an inner rod 13 and a drilling bit 15 arranged at the front side of an outer casing 12 is attached to the inner rod 13. An intermediary double pipe D is constructed of an outer casing 22 and an inner rod 23 for which a polygonal connecting part 23a is formed. With the ground drilling method, an insertion bore is drilled with the inner rod 13 only rotated while the drilling double pipe C is pushed forward, and after that the inner rod 13 only is extracted out of the insertion bore with the outer casing 13 left behind in the insertion bore.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for drilling an insertion hole for mounting a solidifying material or the like on a wall surface of, for example, a mountain tunnel excavated on a defective ground. The present invention relates to a mountain drilling device, a relay double pipe used for the same, and a ground drilling method using the same.

[0002]

2. Description of the Related Art Conventionally, Japanese Unexamined Patent Publication No. 9-2
There is one described in Japanese Patent No. 50287. As shown in FIG. 20, the ground drilling apparatus includes a hydraulic rock drill 1 and an outer casing 3 connected thereto via a coupler 2.
And a double pipe 5 composed of an inner rod 4. These are mounted on a guide shell 6 of a crawler type hydraulic drill jumbo (not shown).

A ring bit 3a is fixed to a tip of the outer casing 3, and a cross bit 4a is fixed to a tip of the inner rod 4, respectively.
The drilling machine 1 applies a turning force and a striking force, and at the same time, applies a pushing force by the guide shell 6 to drill an insertion hole in the ground.

[0004]

However, in the above-mentioned conventional ground drilling apparatus, since the outer casing 3 and the inner rod 4 are both driven to rotate, the insertion hole is drilled. In addition to maintaining the rigidity that can withstand the drilling, it requires a process for attaching a ring bit to the front end thereof, which increases the cost.

In general, when the hole wall of an insertion hole formed in a ground is apt to collapse, such as a defective ground having an expanding property or a falling property, a stress material is inserted into the insertion hole. Although the method of press-fitting a solidified material or the like into the insertion hole through the outer casing is performed while leaving the outer casing as it is, the construction cost increases if the expensive outer casing as described above is left in the insertion hole. There are drawbacks.

Further, slime generated at the front end of the double pipe 5 and generated by drilling is discharged into a gap formed between the inner peripheral surface of the outer casing 3 and the outer peripheral surface of the inner rod 4. The return path 7 for returning the flushing water is formed, but the diameter of the insertion hole to be drilled is small, and as the total length of the insertion hole becomes longer, the discharge path 7 becomes narrower and contains slime. There is a concern that it will be difficult to discharge flushing water.

Therefore, the present invention can employ an inexpensive outer casing, and can discharge flushing water including slime satisfactorily regardless of the diameter of the insertion hole or the entire length thereof, and can reduce the construction time. It is an object of the present invention to provide a ground drilling device which can be shortened, a double pipe for relay used therein, and a ground drilling method.

[0008]

According to the present invention, there is provided a ground drilling apparatus in which an inner rod 13 is provided in an outer casing 12.
Is rotatably accommodated in a double pipe C for drilling, and a coupler B for transmitting a rotational force only to the inner rod 13 thereof.
A drill bit 15 having a larger outer diameter than the outer casing 12 and being disposed at a front side of the outer casing 12 and connected to the rock drill 11 via the front end of the inner rod 13. It is configured to be attached to.

The coupler B is a rod adapter 16 for connecting the inner rod 13 to the shank rod 11a of the rock drilling machine 11, and is rotatably fitted to the rod adapter 16 and supports the outer casing 13. A front adapter 17, and a ring-shaped cushioning member 19 for reducing the impact force applied from the rock drill 11 to the outer casing 12 is provided between the rod adapter 16 and the front adapter 17. The one interposed is preferred.

[0010] At the front edge of the outer casing 12, locking projections 12a are formed, and at the drilling bit 15, detent recesses 15d, 15d for locking the locking projections 12a, 12a are formed. And the inner rod 13
When the inner rod 13 is pulled out of the insertion hole K1, the drill bit 15 and the drill bit 15 are screwed together with a reverse screw that loosens when rotated in the direction opposite to the rotation direction during drilling. The drill bit 15 is detached from the inner rod 13 by rotating the drill bit 15 in a direction opposite to the rotation direction at the time of drilling. When the shank device 14 is attached to the front end of the inner rod 13, the drill bit 15 is screwed into the shank device 14 as a reverse screw that loosens when rotated in the direction opposite to the rotation direction during drilling. I do.

The drill bit 15 is connected to the inner rod 13 via a shank device 14. At the center of the shank device 14, a feed hole 14g for supplying flushing water W to the drill bit 15 is provided. In addition, a plurality of discharge grooves 14d for discharging the flushing water W are formed on the peripheral wall. Further, the shank device 14 has a plurality of flushing water jet holes 14h... Having one end opened in the feed hole 14g and the other end opened in a discharge groove 14d located behind the opening. It is good to form.

The relay double pipe D of the present invention is provided with a connecting portion 23a formed at the front end with a female screw which can be screwed to the rear end of the outer casing 12 and the other inner rods 13, 23, and has a rear end. And an inner rod 2 provided with a connecting portion 23b formed with an external thread that can be screwed into a coupling sleeve attached to a shank rod of a rock drill.
3, and the connecting portion 23a on the front end side is formed in a polygonal shape.

The method for drilling a ground mountain according to the present invention comprises an outer casing 12 and an inner rod 13 which is disposed so as to protrude forward of the outer casing 12 and to which a drill bit 15 having an outer diameter larger than that of the outer casing 12 is attached. While pushing the double pipe C for drilling made by the rock drill 11, only the inner rod 13 is rotated to drill the insertion hole K 1,
After drilling is completed, the inner rod 13 is detached from the drill bit 15 and pulled out from the insertion hole K1 while the outer casing 12 is left in the insertion hole K1.

In this case, the inner rod 13 and the drill bit 15 are screwed together as a reverse screw which loosens when rotated in the direction opposite to the rotation direction during drilling, and only the inner rod 13 is inserted into the insertion hole. When the inner rod 13 is removed from the hole K1, the inner rod 13 may be rotated in the direction opposite to the direction at the time of drilling so that the inner rod 13 is detached from the drill bit 15. In addition, a variable-diameter bit capable of expanding and contracting the outer diameter is attached to the inner rod 13, and the inner rod 1
When extracting 3 from the insertion hole K1, the variable diameter bit may be reduced in diameter, and may be extracted from the insertion hole together with the inner rod 13.

[0015]

Embodiments of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, the ground drilling apparatus A of the present invention is mounted on a guide shell 10 of a hydraulic drill jumbo 9 that can travel in a tunnel 8.
A hydraulic rock drill 11, connected thereto via a coupler B,
A drilling double pipe C composed of an outer casing 12 and an inner rod 13, and a drilling bit 1 attached to the inner rod 13 via a shank device 14.
5 is provided.

The coupler B, as shown in FIG. 4, comprises a rod adapter 16, a front adapter 17, a coupling sleeve 18, and a buffer ring 19 as a buffer member.

As shown in FIG. 5, the rod adapter 16 has a cylindrical mounting portion 16a and a rod portion 16b having a diameter smaller than that of the cylindrical mounting portion 16a. At the center of the mounting portion 16a, a female screw 16c for screwing the shank rod 11a of the hydraulic rock drill 11 is formed, and at the front half of the rod portion 16b, a male screw 16c is formed.
d is formed.

The front end face 16e of the rod portion 16b and the female screw 1
A supply hole 16g for supplying flushing water W supplied via the hydraulic rock drill 11 is formed between the inner surface 16f and the inner back surface 16f of the hydraulic rock drill 11. 16h is a wrench flat.

The front adapter 17 is shown in FIGS.
As shown in FIG. 7, the rod adapter 16 is provided in the rear end wall 17a.
Is formed in a cylindrical body having a fitting hole 17b which is slidably fitted into the rod portion 16b of the front adapter 1 by the rotational force applied to the rod adapter 16 by the hydraulic rock drilling machine 11.
7 is not transmitted. On the front end surface of the front adapter 17, a step 17c is formed for fitting the rear end of the outer casing 12, and
On the front end side of the peripheral wall, discharge holes 17d for discharging flushing water containing slime are formed to face each other.

The coupling sleeve 18 is for connecting the inner rod 13 to the rod adapter 16 and has an outer diameter that can be freely inserted into the front adapter 17 as shown in FIGS. And a rectangular cylinder having a predetermined length.

At the center of the inner peripheral surface of the coupling sleeve 18, a stopper 1 abuts on the front end of the rod portion 16 b of the rod adapter 16 and the rear end of the inner rod 13.
8a is formed to protrude in a ring shape. Also, one of the two end portions of the inner peripheral surface has a male screw 16 of the rod portion 16b.
A female screw 18b for screwing d is formed, and a female screw 18c for screwing to a male screw 13a as a connecting portion of the inner rod 13 described later is formed on the other side.

The buffer ring 19 is shown in FIG.
As shown in (B), the rod portion 1 of the rod adapter 16
A play insertion hole 19a into which the 6b can be inserted is formed at the center, and is made of a material capable of reducing the impact force applied to the outer casing 12 from the hydraulic rock drill 11 via the rod adapter 16, specifically, chloride. It is formed of synthetic resin such as vinyl.

The outer casing 12 has a total length of 3000.
mm, outer diameter 60.5mm, wall thickness about 5.5mm,
It is an elongated cylindrical body as shown in FIGS. 3 and 4, and is formed of, for example, synthetic resin or steel. The outer casing 12 is not necessarily required to have the strength capable of withstanding the excavation of the ground by attaching the above-described ring bit to the front end of the outer casing 12, and the outer casing 12 is left in the insertion hole formed in the ground. Sometimes, any material having enough strength to withstand the external force applied thereto may be used.

A plurality of injection holes (not shown) for injecting the solidified material pressed into the outer casing 12 into the ground are formed in a peripheral wall of the outer casing 12, for example, in a staggered arrangement. In addition, locking protrusions 12a, 12a for locking the drill bit 15 attached to the inner rod 13 are formed on the front edge.

The inner rod 13 has a total length of 3050 mm,
It is an elongated rod-like body having a diameter of about 32 mm as shown in FIGS. 3 and 4. Male screws 13a, 13a are formed at both ends of the outer peripheral surface as connecting portions. A supply hole 13b for supplying flushing water supplied via the hydraulic rock drill 11 is formed.

The shank device 14 is shown in FIGS.
As shown at 0 and 11, a bit holding portion 14b is integrally provided at the front end of the shank portion 14a. The shank portion 14a is provided at the center on the rear end side of the inner rod 13a.
And a female screw 14c to be screwed with the male screw 13a. On the outer peripheral surface of the shank portion 14a, three discharge grooves 14d for discharging flushing water containing slime are formed parallel to each other and at 120-degree intervals from the front end to the rear end.

The bit holding section 14b includes a shank section 1
It has a cylindrical shape smaller in diameter than 4a, and has a male screw 14e for screwing a drill bit on its outer peripheral surface. The male screw 14e is tightened by turning in the direction of rotation of the inner rod 13 when drilling the insertion hole, and is screwed into a reverse screw which is loosened by turning in the opposite direction. Also, the front end face of the shank device 14 and the female screw 1
4c, between the inner back surface 14f and the center of the feed hole 1f.
4 g are formed.

In the thickness of the shank portion 14a, the feed hole 1 is provided.
Three flushing water ejection holes 14h, which are open at one end at 4g and open at the other end at the bottom surface of the discharge groove 14d located at the rear side of the opening, are formed at intervals of 120 degrees from each other. That is, the flushing water jet holes 14h ...
Is a part of the flushing water flowing through the feed hole 14g,
It has a function of forcibly discharging flushing water containing slime generated around the drill bit 15 by jetting it into the drain groove 14d.

As shown in FIGS. 12 and 13, the drill bit 15 is formed by integrally forming a blade portion 15a having a diameter equal to or slightly larger than the outer diameter of the outer casing 12 on the front end surface of the main body 15b. In the main body 15b, a female screw 15c that is screwed to the male screw 14e of the bit holding portion 14b of the shank device 14 is formed. Further, the drill bit 15 and the shank device 14 are separated from each other by rotating the drill bit 15 and the shank device 14 in a direction opposite to the rotation direction at the time of drilling. Further, at the rear end portion of the peripheral wall of the main body 15b, the detent recesses 15d, 1d for locking with the locking projections 12a, 12a of the outer casing 12.
5d (one not shown) is formed.

Further, the front wall surface 15e of the female screw 15c
Of flushing water 1 between the nozzle and the front of the blade 15a.
5f is formed, and in the feed hole 15f,
Two branch holes 15g, 15g for discharging flushing water are formed on the front surface of the blade 15a.

An inner rod 13 is connected to the rod adapter 16 via a coupling sleeve 18, and a drill bit 15 is screwed to the inner rod 13 via a shank device 14, so that the inner parts of the inner rod 13 are connected to each other. The feed holes 16g, 13b, 14g, and 15f respectively formed in a single line form one continuous feed path. Therefore,
The flushing water supplied to the rod adapter 16 via the hydraulic rock drill 11 passes through the drilling bit 1
5 is discharged to the front surface of the blade portion 15a.

The discharge groove 1 of the shank device 14
4d, a continuous discharge path is formed by an annular gap formed between the inner wall surface of the outer casing 12 and the outer peripheral surface of the inner rod 13. Therefore, the double pipe C for drilling
The flushing water containing slime generated at the front end of the drill bit 15, that is, the slime generated at the front surface of the drill bit 15, is discharged to the outside through the discharge holes 17d of the front adapter 17 through the discharge path.

Further, a part of the flushing water flowing in the above-mentioned feed passage is blown out to the discharge passage through the flushing water discharge holes 14g of the shank device 14, and the flushing water containing the slime of the discharge passage is forcibly removed. Functions to discharge.

The ground drilling device having the above-described configuration provides
The ground drilling method of the present invention for drilling an insertion hole in a face will be described mainly with reference to FIGS. For example, the hydraulic drill jumbo 9 is moved to a required position of the tunnel 8 in accordance with the position where the solidified material is injected, and the boom 2 is moved.
1 (FIG. 1), the guide shell 10 is supported substantially horizontally, and the drill bit 15 is opposed to the face K as shown in FIG.

When the hydraulic rock drill 11 is driven, the inner rod 13 is driven to rotate, and a striking force is applied to the drilling double pipe C. At this time, since the buffer ring 19 is interposed between the front adapter 17 supporting the outer casing 12 and the rod adapter 16, the impact force from the hydraulic rock drill 11 is applied to the outer casing 12. It is transmitted in a relaxed state by the buffer ring 19. Therefore, for example, the outer casing 12
There is no problem even when the resin itself is formed of a synthetic resin.

Further, a pushing force toward the face K is applied to the drilling double pipe C by a feed mechanism (not shown) of the hydraulic drilling machine 11, and as shown in FIG. The drilling of K1 is performed, and the hydraulic rock drilling machine 11 is supplied with flushing water from a pump unit (not shown).

The flushing water is supplied to the feed holes 16g and 13g.
b, 14g, and 15f are fed to the front of the drill bit 15 through the above-described feed path, and the slime generated around the drill bit 15 is washed out. The holes 17d are discharged to the outside through the holes 17d.

As shown in FIG. 16, when the drilling to the predetermined drilling length is completed, as shown in FIG. 17, the inner rod 13 is drilled while the outer casing 12 is left in the insertion hole K1. Pull out while rotating in the opposite direction to the direction of rotation.

When the inner rod 13 is pulled out while being rotated in the opposite direction, the locking recess 15 d of the drill bit 15 is inserted halfway along the way.
2a. After engagement, the inner rod 13
Are rotated in the same direction, only the shank device 14 and the inner rod 13 rotate while the drill bit 15 is locked in the outer casing 12. As a result, the drill bit 15 separates from the shank device 14, that is, from the inner rod 13, and the drill bit 1
5 at the front end of the outer casing 12,
Only the inner rod 13 can be extracted from the outer casing 12.

Thereafter, the solidified material L is injected into the outer casing 12 left in the insertion hole K1. As shown in FIG. 18, the solidified material L injected into the outer casing 12 is injected into the ground through an injection hole (not shown) formed in the outer casing 12, and the ground around the insertion hole K1 is removed. Solidify and reinforce.

The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the invention. For example, in the case where the insertion hole to be drilled is deep and cannot be drilled using only the double pipe C for drilling, FIG.
(A) and (B), the required number of relay double tubes D of the present invention are connected and used.

The double pipe D for relaying comprises an outer casing 22 and an inner rod 23, as in the double pipe C for drilling, but the structure of the inner rod 23 is different.

The inner rod 23 is an elongated rod-like body formed to have a total length of 3050 mm and a diameter of about 32 mm similarly to the inner rod 13 described above.
A connecting portion 23a formed with a female screw screwed into the third male screw 13a is formed at the front end, and a connecting portion 23b formed with a male screw screwed into the female screw 18c of the coupling sleeve 18 is formed at the rear end. Have been. In addition, 23c is a feed hole.

The connecting portion 23a on the front end side is used to discharge flushing water including slime so that a sufficient gap is formed between the peripheral wall surface thereof and the inner peripheral surface of the outer casing 22. In order to form a sufficient discharge path, they are formed in a quadrangular shape having flat surfaces 23d at intervals of 90 degrees.

In the above description, an example in which the drill bit is left in the insertion hole has been described. However, when the inner rod is pulled out of the insertion hole by using a variable diameter bit capable of expanding and contracting the outer diameter, the inner rod is retracted into the outer casing. Thus, the diameter of the variable diameter bit may be reduced so as to be extracted together with the inner rod. Thereby, the construction cost can be further reduced.

In the above description, the shank device is attached to the front end of the inner rod, and the drill bit is screwed to the shank device. For example, the shank device slides along the inner wall surface of the outer casing at the front end of the inner rod. In addition to forming a large diameter portion as possible, the inner rod may have a configuration in which a reverse-threaded male screw is formed at the front end of the inner rod, and the drill bit may be directly screwed to the male screw without using a shank device. .

[0047]

According to the drilling apparatus of the first to ninth aspects, it is not necessary to attach a ring bit or the like to the front end of the outer casing, so that the outer casing itself has lower rigidity than the conventional one. In addition, since the structure can be simple, the manufacturing cost can be reduced. Therefore, even when adopting a construction method in which the outer casing is left in the insertion hole drilled in the ground, it can be performed at low cost. In addition, since the thickness can be reduced and the diameter can be reduced as compared with the conventional outer casing to which the ring bit is attached, an insertion hole having a smaller diameter can be quickly drilled.

In addition to the above-mentioned common effects obtained by the ground drilling apparatus according to the first to ninth aspects, the following effects can be obtained by the ground drilling apparatus according to the respective claims. According to the ground drilling device of claim 2, the connector is a rod adapter that connects the inner rod to the shank rod of the rock drill, and is rotatably fitted to the rod adapter, and
Since the configuration includes the front adapter that supports the outer casing, it is possible to drive only the inner rod without rotating the outer casing, with a simple configuration.

According to the third or fourth aspect of the present invention, the buffer member for reducing the impact force applied to the outer casing from the rock drill is inserted between the rod adapter and the front adapter. As a result, the striking force applied to the outer rod can be reduced.

According to the fifth aspect of the present invention, since the outer casing is formed of a synthetic resin, it can be manufactured at extremely low cost.

According to the sixth aspect of the present invention, a locking projection is formed on the front edge of the outer casing, and the drill bit is locked by the locking projection. Since the locking recess is formed and the inner rod and the drill bit are screwed together with a reverse screw that loosens when rotated in the direction opposite to the rotation direction during drilling, the inner rod is screwed. While rotating in the opposite direction to the direction of drilling,
The drill bit can be easily detached from the inner rod by only a simple operation of extracting the drill bit from the outer casing.

According to a seventh aspect of the present invention, a shank device is attached to the front end of the inner rod, and the drill bit is provided in the rotation direction during drilling with respect to the shank device. It is screwed with a reverse screw that loosens when rotated in the opposite direction, so it is possible to remove the inner rod simply by pulling it out of the outer casing while rotating it in the direction opposite to the rotation direction when drilling. The hole bit can be easily detached from the shank device.

According to the drilling device of the eighth aspect, a feed hole for supplying flushing water to the drill bit is formed at the center of the shank device, and the peripheral wall has: Since a plurality of discharge grooves for discharging flushing water are formed, regardless of the diameter and length of the insertion hole, the flushing water supplied to the drill bit through the feed hole is satisfactorily discharged. be able to.

According to the ground drilling device of the ninth aspect, the shank device has one end opened in the feed hole and the other end in the discharge groove located behind the opening. Since a plurality of open flushing water jet holes are formed,
Flushing water containing slime in the discharge channel can be forcibly discharged by the flushing water blown out from the flushing water discharge hole.

According to the relay double pipe of the tenth aspect,
In addition to providing a connecting part formed with a female screw at the front end,
Since the inner rod provided with the connecting portion formed with a male screw at the rear end is provided, even when the relay double pipe is connected to the drilling double pipe and used, the inner wall surface of the outer rod and the inner wall surface of the outer rod are not removed. A discharge path sufficient to allow flushing water containing slime to flow between the connecting portion can be formed, and thereby flushing water containing slime can be satisfactorily discharged.

According to the ground drilling method of the eleventh aspect,
While pushing a drilling double pipe consisting of an outer casing and an inner rod with a drilling bit with a larger outer diameter by a rock drill, only the inner rod is rotated to cut the insertion hole. After drilling, after drilling is completed, with the outer casing left in the insertion hole, the inner rod is detached from the drill bit and pulled out from the insertion hole.
The outer casing itself can be used as a stress material, and since the outer casing is not pulled out, the construction time can be significantly reduced.

[0057] According to the method for drilling a ground mountain according to claim 12,
When the inner rod and the drill bit are screwed together as a reverse screw that loosens when rotated in the direction opposite to the rotation direction during drilling, when pulling out only the inner rod from the insertion hole,
Since the inner rod is rotated in the direction opposite to the direction of drilling to separate the inner rod from the drill bit, only the inner rod can be easily extracted from the outer casing.

According to the thirteenth aspect of the present invention,
While pushing a double pipe for drilling consisting of an outer casing and an inner rod with a variable diameter bit that is arranged to protrude from the front side of the outer casing and is capable of expanding and contracting the outer diameter, the rock drill is used to push the pipe. Only the inner rod is rotated to drill the insertion hole.After drilling is completed, the diameter variable bit is reduced while the outer casing remains in the insertion hole, and this is removed from the insertion hole together with the inner rod.
Only the outer casing can be left in the insertion hole, so that the construction cost can be further reduced.

[Brief description of the drawings]

FIG. 1 is a side view of a state in which a hydraulic drill jumbo equipped with a ground drilling device of the present invention is arranged in a tunnel.

FIG. 2 is a side view of the ground drilling device.

FIG. 3 is an enlarged cross-sectional view of a front half of a double pipe for drilling.

FIG. 4 is an enlarged cross-sectional view of the latter half.

FIG. 5 is a side view showing a part of the rod adapter in a cutaway manner.

FIG. 6 is a sectional view of a front adapter.

FIG. 7 is a front view of the same.

8A and 8B show a coupling sleeve, wherein FIG. 8A is a cross-sectional view thereof, and FIG. 8B is a front view thereof.

9A and 9B show a buffer ring, in which FIG. 9A is a side view in which a part of the ring is shown in cross section, and FIG.

FIG. 10 is a sectional view of a shank device.

FIG. 11 is a sectional view taken along line II of FIG. 10;

FIG. 12 is a side view showing a part of a drill bit in a cutaway manner.

FIG. 13 is a front view of the same.

FIG. 14 is a side view of a state in which the double pipe for drilling is opposed to the face face.

FIG. 15 is a side view in the middle of drilling by the drilling double pipe.

FIG. 16 is a side view in which drilling by the drilling double tube is completed.

FIG. 17 is a side view in which the outer casing is left in the insertion hole and the drill bit is detached, and only the inner rod is pulled out from the insertion hole.

FIG. 18 is a side view showing a state where a solidified material is injected into the ground via an outer casing.

FIG. 19 shows a relay double pipe of the present invention, and (A)
Is a cross-sectional view thereof, and (B) is a front view thereof.

FIG. 20 is a side view showing a main part of a conventional ground drilling apparatus in a cutaway manner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Rock drill 11a Shank rod 12 Outer casing 12a Locking projection 13 Inner rod 14 Shank device 14h Flushing water jetting hole 14d Drainage groove 14g Feeding hole 15 Drilling bit 15a Detent for stopping 16 Rod adapter 17 Front adapter Reference Signs List 19 buffer ring 23 as a buffer member 23 inner rod 23a front end side connection part 23b rear end side connection part A ground drilling device B coupler C drilling double pipe D relay double pipe K faceted face K1 insertion hole

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) E21D 20/02 E21D 20/02

Claims (13)

[Claims] 1. A drilling double pipe having an inner rod rotatably housed in an outer casing is connected to a rock drill through a coupler transmitting torque only to the inner rod. A ground drilling bit, which is arranged so as to protrude toward the front side of the outer casing and has an outer diameter larger than that of the outer casing, is attached to a front end of the inner rod. apparatus. 2. A coupling device comprising: a rod adapter for coupling an inner rod to a shank rod of a rock drill, and a front adapter rotatably fitted to the rod adapter and supporting an outer casing. The mountain drilling device according to claim 1, wherein 3. The ground drilling hole according to claim 2, wherein the coupler has a buffer member for reducing a striking force applied to the outer casing from the rock drilling machine between the rod adapter and the front adapter. apparatus. 4. The mountain drilling device according to claim 3, wherein the buffer member is formed in a ring shape to be fitted to the rod adapter. 5. The ground drilling device according to claim 1, wherein the outer casing is formed of a synthetic resin. 6. A locking projection is formed on the front edge of the outer casing, and a turning recess is formed on the drill bit to be locked by the locking projection. 6. The ground drilling hole according to claim 1, wherein the rod and the drill bit are screwed together as a reverse screw which loosens when rotated in a direction opposite to the rotation direction during drilling. apparatus. 7. A shank device is attached to a front end of the inner rod, and the drill bit is provided with a reverse screw which is loosened with respect to the shank device when rotated in a direction opposite to a rotation direction at the time of drilling. The drilling device according to claim 1, 2, 3, 4, or 5, which is screwed together. 8. The shank device has a feed hole formed at the center of the shank device for supplying flushing water to the drill bit, and a plurality of discharge holes for discharging flushing water formed on a peripheral wall thereof. 8. The mountain drilling device according to claim 7, wherein a groove is formed. 9. The shank device has a plurality of flushing water ejection holes having one end opened in the feed hole and the other end opened in a discharge groove located behind the opening. The mountain drilling device according to claim 7 or 8, wherein: 10. A connecting portion formed at the front end with an outer casing and a female screw capable of being screwed to another inner rod, and a male screw screwed to a coupling sleeve attached to a shank rod of a rock drill. A relay double pipe comprising: an inner rod provided with a formed connecting portion at a rear end; and a connecting portion on a front end side thereof is formed in a polygonal shape. 11. A rock drilling machine cuts a double pipe for drilling comprising an outer casing and an inner rod having a drilling bit having an outer diameter larger than that of the outer casing and protruding from a front side of the outer casing. While pushing, only the inner rod is rotated to drill the insertion hole, and after drilling is completed, the inner rod is detached from the drill bit and pulled out from the insertion hole while the outer casing remains in the insertion hole. A mountain drilling method characterized by the following. 12. The inner rod and the drill bit are screwed together as a reverse screw that loosens when rotated in a direction opposite to the rotation direction during drilling. 12. The method for drilling a ground pile according to claim 11, wherein the inner rod is rotated in a direction opposite to a direction at the time of drilling to be separated from the drill bit. 13. A rock drilling machine presses a double pipe for drilling comprising an outer casing and an inner rod having a variable-diameter bit which is arranged to protrude in front of the outer casing and has an outer diameter which can be enlarged and reduced. While moving forward, only the inner rod is rotated to drill the insertion hole.After the drilling is completed, the diameter variable bit is reduced while the outer casing remains in the insertion hole, and this is inserted together with the inner rod. A ground drilling method characterized by extracting from a hole.