JP2000291358A - Large calibre boring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discharge excavation slime smoothly without damaging natural ground in a large calibre hole boring. SOLUTION: When a natural ground C is reinforced by burying a steel outer tube 24, a drifter 26 is driven to transmit a thrust, rotation, and hammering to an inner tube rod 22 and a boring bit 20 through a shank rod 38 in order to dig the natural ground C and form a bored hole D. In this case, cooling medium A comprising air bubbles F accompanying compressed air E is supplied to a medium supply passage 28 through a supply port 34, and the cooling medium A is injected from the boring bit 20 to the natural ground C. The powder generated by the excavation with the boring bit 20 is mixed with the cooling medium A to form excavation slime B, and the excavation slime B is discharged to the outside from a discharge port 36 through a discharge passage 30.

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 large-diameter holes, and more particularly to a technique for discharging excavated slime when excavating large-diameter holes.

[0002]

2. Description of the Related Art In tunnel excavation work on a ground with many cracks and slip surfaces, a sedimentary ground, a low-strength soft rock, or an expansive ground, it is necessary to secure the stability of the ground before excavation. There is. As one of the construction methods for stabilizing the ground having such properties, a long steel pipe front receiving construction method is known.

[0003] Fig. 3 shows a typical construction state of the ground drilling method in the long steel pipe tip receiving method. In the drilling method shown in FIG. 1, an inner pipe rod 2 having a drill bit 1 attached to a tip end, an outer pipe 3 accommodating the inner pipe rod 2 therein, and a thrust and rotation are applied to the drill bit 1. And a drifter 4 for applying an impact.

[0004] The inner pipe rod 2 is a rod body having a screw engraved on both ends, and is successively added and connected via a coupling as the excavation progresses.
A medium supply passage 5 for supplying a cooling medium a is formed to pass therethrough.

[0005] The outer pipe 3 is a hollow cylindrical steel pipe having threads cut at both ends. Like the inner pipe rod 2, the ends are mutually screwed together as the excavation progresses. The gap between the inner pipe rod 2 and the outer peripheral surface of the inner pipe rod 2 inserted therein constitutes a discharge passage 6 for excavation slime b generated with excavation.

A swivel 7 is mounted on the rear end side of the outer pipe 3. The swivel 7 has a supply port 8 for the cooling medium a communicating with the medium supply passage 5 of the inner pipe rod 2 and a discharge port 6. An outlet 9 for the excavating slime b communicating with the slime b is provided.

The drifter 4 is connected to the inner pipe rod 2 via a shank rod 10. Drifter 4
Is supported by a guide cell 12 via a guide shoe 11 provided at the lower end so as to be movable back and forth.

At the distal end of the guide cell 12, a sentizer 13 for positioning and supporting the outer tube 3 is provided.
When the steel pipe is buried to reinforce the ground c, the thrust, rotation and impact are transmitted to the inner pipe rod 2 and the drill bit 1 via the shank rod 10 by driving the drifter 4. As a result, the ground c is excavated to form a hole d.

At this time, a cooling medium a selected from drilling water or air is supplied to the medium supply passage 5 through the supply port 8, and the cooling medium a is transferred from the drill bit 1 to the ground c. Injected toward.

The cutting powder drilled by the drill bit 1 is:
Mixed with the cooling medium a to form drilling slime b,
The excavation slime b is discharged from the discharge port 9 to the outside via the discharge passage 6.

Since the thrust and the impact of the drifter 4 are applied to the outer pipe 3 from the rear end side in the drilled hole d excavated by the drill bit 1, the outer pipe 3 is drilled by the pushing method. Inserted in d.

However, such a conventional drilling method particularly has a large diameter, for example, 65 mm in diameter.
When forming the above-mentioned large-diameter hole, there were technical problems described below.

[0013]

That is, the diameter is 65.
In the case of forming a drilled hole having a large diameter of not less than mm, the amount of drilling powder drilled by the drilling bit 1 becomes very large, and therefore, the amount of drilling slime b to be discharged naturally becomes large.

However, if a large amount of drilling slime b is to be discharged by drilling water or air, a large amount of drilling water or air is required. When a large amount of air is used, a large amount of dust is generated, and the working environment is similarly deteriorated.

The exclusion of the excavation slime b is based on securing the flow velocity in the discharge passage 6. As the drilling diameter increases, the removal medium (drilling water or air) increases in proportion to the square of the diameter. ) Increases, leading to a deterioration of the working environment. On the other hand, the double-pipe type drilling method using the inner pipe rod 2 and the outer pipe 3 as shown in FIG. 3 is a method adopted when the excavation ground c is relatively soft. In the drilling method, when the outer pipe 3 is buried in the ground c by a predetermined length, the inner pipe rod 2 is pulled out. At this time, the outer pipe 3 is contained in the excavation slime b in the discharge passage 6. If the dust remains, it becomes very difficult to pull out the inner tube rod 2.

[0016] Such a problem associated with the residue of the bobbin dust can be avoided by, for example, increasing the supply pressure of drilling water or air.
Another problem occurs in that the ground c is cracked, the slip surface is loosened, and the ground c is damaged.

The present invention has been made in view of such a conventional problem, and an object of the present invention is to smoothly discharge excavation slime without damaging the ground, An object of the present invention is to provide a large-diameter drilling method that does not cause deterioration of the environment.

[0018]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an inner pipe rod equipped with a drill bit for drilling a large bore having a diameter of 65 mm or more, and an inner pipe rod including the drill bit. Using an outer pipe housed inside, drilling a hole while applying thrust, rotation and impact to the drill bit, and when drilling this hole, a medium supply provided inside the inner pipe rod A cooling medium is supplied from the passage to the drill bit, and excavation slime accompanying the excavation is discharged to the outside through a slime discharge passage provided between the inner pipe rod and the outer pipe. In the drilling method for inserting the outer tube into the hole, air bubbles mixed with compressed air are used as the cooling medium. According to the large-diameter drilling method configured in this way, the air bubbles used for the cooling medium are higher in viscosity than liquids such as drilling water, and the gaps, cracks, and slip surfaces of the soil particles that form the ground are formed. Low permeability to For this reason, geology whose strength is reduced by contact with water,
There is no problem of damage to the ground, such as cracks and loosening of the slip surface. In addition, the excavated slime in which bubbles and cuttings are mixed becomes a state in which excavated soil particles (cuttings) adhere to the surface of the bubbles, so that the soil particles in the excavating slime are turned into clay and formed in the discharge passage. Adherence or sedimentation of the particles does not hinder discharge. Furthermore, the excavation slime in which bubbles and cuttings are mixed is in a state in which the excavated soil particles (cuttings) adhere to the surface of the bubbles, so that dust is not generated unlike air drilling, Also, a large amount of turbid water is not generated unlike the drilling water. The air bubbles are generated by mixing a foaming agent mixture and compressed air, and the air bubbles can be generated immediately before or inside the medium supply passage. According to this configuration, it is possible to supply bubbles having a high viscosity and a large loss due to the pressure feeding in the pipeline in a state where the pressure feeding loss is relatively small. The foam can be defoamed by mixing an antifoaming agent with the excavation slime.
According to this configuration, in the excavation slime in which the bubbles and the cutting powder are mixed, the bubbles are defoamed and the volume is reduced with time, but by mixing the defoaming agent,
It can be defoamed in a short time. A power transmission portion such as the thrust may be provided at a distal end side of the outer tube, and the outer tube may be inserted into the borehole by a forward pulling method. According to this configuration, unlike the conventional pushing method, it is not necessary to provide a power transmission portion such as a thrust at the rear end side of the outer pipe, and the rear end side of the outer pipe can be opened. A structure suitable for discharging slime can be obtained. The power transmission portion includes a step portion provided on an inner peripheral surface of a casing shoe screwed and connected to a tip of the outer tube, and a convex portion provided on an outer peripheral surface of the drill bit and abutting on the step portion. Can be configured. According to this configuration, with a simple structure, the outer tube can be inserted into the borehole in a forward pulling method. In addition, when the outer pipe is inserted by such a forward pulling method, a system using an air blow for removing the drilling slime is provided, but the speed of the drilling slime that jumps out from the end of the outer pipe is extremely large. However, the slime scatters near the workplace, significantly deteriorating the environment of the workplace, and at the same time, hitting the scattered excavation slime, it is injured, so it is dangerous enough to be unable to approach during drilling. Then, such a problem can be solved.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. 1 and 2 show an embodiment of a large-diameter drilling method according to the present invention.

In the drilling method shown in FIG. 1, an inner pipe rod 22 having a drill bit 20 attached to a tip end thereof, an outer pipe 24 accommodating the inner pipe rod 22 therein, and a drill bit 20 are provided.
And a drifter 26 for applying thrust, rotation, and impact to the vehicle.

The inner pipe rod 22 is a rod body having a screw engraved on both ends, and is successively added and connected via a coupling as the excavation progresses. A medium supply passage 28 for supplying the cooling medium A is formed therethrough.

The outer pipe 24 is a hollow cylindrical steel pipe having threads cut at both ends. Like the inner pipe rod 22, the outer pipe 24 has its ends screwed together with the progress of excavation. Between the outer peripheral surface of the inner pipe rod 22 and the excavation slime B generated with the excavation.
Discharge passage 30.

At the rear ends of the inner tube rod 22 and the outer tube 24,
A swivel 32 is attached to the swivel 32. The swivel 32 has a supply port 34 for the cooling medium A communicating with the medium supply passage 28 of the inner pipe rod 22, and a drilling slime B communicating with the discharge passage 30.
Outlet 36 is provided.

The drifter 26 is connected to the inner tube rod 22 via a shank rod 38. The drifter 26 is supported by a guide cell 42 via a guide shoe 40 provided at the lower end so as to be movable back and forth.

A guide riser 46 for positioning and supporting the outer tube 24 is provided on the distal end side of the guide cell 42. The basic configuration as such a drilling method is the same as a conventional method of this type, but the drilling method of the present embodiment is particularly suitable for excavating a large-diameter hole having a diameter of 65 mm or more. This method is suitable for the following, and has the following remarkable features.

That is, first, in the drilling method according to the present embodiment, the air bubble F mixed with the compressed air E is used as the cooling medium A. For this reason, a mixer 48 is connected to the supply port 34 of the swivel 32 communicating with the medium supply passage 28.

A compressor 50 for supplying compressed air E and a pump 52 for supplying a mixed solution G containing a foaming agent such as a surfactant are connected to the mixer 48.
The mixer 48 receives the supply of the compressed air E and the mixed solution G immediately before the medium supply passage 28.

The mixed solution G containing the foaming agent and the compressed air E sent from the pump 52 are converted into a gas-liquid two-phase state by a swivel 32.
to go into. The two-phase flow passes through a complicated passage in the swivel 32 and enters the medium supply passage 28, and the swivel 3
When the gas passes through the passage 2, it foams and becomes a bubble F and the passage 2
8 is supplied.

The position where the bubble F is generated is determined not only immediately before the medium supply passage 28 shown in FIG.
8, the compressed air E and the mixed solution G are fed into the medium supply passage 28 in a gas-liquid two-phase state as disclosed in Japanese Patent No. 2666600, and bubbles are generated near the drill bit 20. F may be generated.

FIG. 2 is an enlarged view of the vicinity of the drill bit 20 shown in FIG. 1. The drill bit 20 of this embodiment is composed of a ring lost bit 20a and an inner bit 20b. It is composed, ring lost bit 2
The inner bit 20b fitted to Oa is inserted inside the casing shoe 54.

The distal end of the inner tube rod 22 is screwed to the rear end of the inner bit 20b, and the outer peripheral surface thereof has a concave groove 20c divided in the circumferential direction.
Are provided along the axial direction of the inner bit 20b.

The casing shoe 54 is a hollow cylindrical body having both ends opened. The front end of the outer tube 24 is fitted and connected to the rear end of the casing shoe 54, and the rear end of the ring lost bit 20a is connected to the front end. The outer peripheral part is fitted.

The medium supply passage 28 provided inside the inner pipe rod 22 extends through the inner bit 20b in the axial direction and opens at the tip of the inner bit 20b.

The distal end of the concave groove 20c provided on the outer periphery of the inner bit 20b is opened at the outer peripheral edge of the distal end of the inner bit 20b, and the rear end of the concave groove 20c is connected to the inner pipe rod 22.
And the discharge passage 30 of the excavation slime B provided between the outer peripheral surface of the outer pipe 24 and the inner peripheral surface of the outer pipe 24.

A power transmitting portion 56 for thrust and striking force applied from the drifter 26 is provided between the inner bit 20b and the casing shoe 54. The power transmission portion 56 of this embodiment includes a step portion 58 provided on the casing shoe 54 and a convex portion 60 provided on the inner bit 20b.

The step portion 58 is provided substantially at the center of the casing shoe 54 in the axial direction, and is provided on the inner peripheral surface thereof.
The protruding portion 60 is formed so as to protrude from the rear end side outer periphery of the inner bit 20b, is divided by the concave groove 20c, and is
The projection 60 and the projection 60 are in contact with each other.

When a thrust and a striking force are applied to the inner pipe rod 22 from the drifter 26 in a state where the stepped portion 58 and the protruding portion 60 are in contact with each other, the thrust and the striking force are applied through the contact portion. Is also transmitted to the outer tube 24 via the casing shoe 54, whereby the outer tube 24 can be inserted into the hole D by a forward pulling method.

When the ground C is reinforced by burying the outer pipe 24 made of steel pipe, by driving the drifter 26, the thrust, rotation and impact are reduced by the shank rod 38 and the inner pipe rod 22 and The drill bit D is transmitted to the hole bit 20, whereby the ground C is excavated to form a hole D.

At this time, compressed air is supplied through the supply port 34.
A cooling medium A composed of air bubbles F mixed with E is supplied to a medium supply passage 28, and the cooling medium A
It is injected from 0 toward the ground C.

The cuttings drilled by the drill bit 20 are mixed with the cooling medium A to form drilling slime B. The drilling slime B is discharged to the outside through the discharge passage 36 through the discharge passage 30.

The excavated slime B discharged to the outside contains bubbles F. The bubbles F in which a surfactant or the like is foamed disappear with the passage of time. When foaming is desired, the foam F contained in the excavation slime B can be foamed by spray mixing an antifoaming agent.

In the borehole D drilled by the drill bit 20, the thrust and the impact of the drifter 26 are applied to the outer pipe 24 from its front end side. It is inserted into the hole D.

By continuing such an operation, when the outer pipe 24 is buried in the ground C having a predetermined length, the operation is stopped, the inner pipe rod 22 is collected together with the inner bit 20b, and the hole is drilled. End the process.

According to the large-diameter drilling method performed as described above, the air bubble F mixed with the compressed air E is used as the cooling medium A. Compared to liquids such as water, the viscosity is high and the permeability to the gaps, cracks and slip surfaces of the soil particles forming the ground C is small.

Therefore, there is no problem that the ground C is damaged by contact with water, that is, geology whose strength is reduced, cracks and slip surfaces are loosened.

The excavation slime B in which the bubbles F and the cuttings are mixed is formed by excavating the soil particles (cuttings) on the surface of the bubbles F.
Is attached, so that the soil particles in the excavation slime B are clayified and adhere to the discharge passage 30, or
The particles do not settle and hinder the discharge.

Further, the excavated slime B in which the bubbles F and the cuttings are mixed is in a state where the excavated soil particles (cuttings) adhere to the surface of the bubbles F, so that the dusts are removed like the air drilling holes. No turbid water is generated as in the case of drilling water.

In this embodiment, the bubbles F are generated by mixing the foaming agent mixture G and the compressed air E. The generation of the bubbles F is performed immediately before the medium supply passage 28. Therefore, it is possible to supply the bubble F having a high viscosity and a large loss due to the pressure feeding in the pipeline in a state where the pressure feeding loss is relatively small. In this case, if the foaming agent mixture liquid G and the compressed air E are sent in a gas-liquid two-phase state to generate bubbles F near the drill bit 20,
Loss can be further reduced.

In the case of the present embodiment, a power transmission portion 56 such as a thrust is provided at the distal end side of the outer tube 24, and the outer tube 24 is inserted into the hole D by a forward pulling method. According to this configuration, unlike the conventional pushing method, it is not necessary to provide a power transmission portion such as thrust at the rear end side of the outer tube 24, and the rear end side of the outer tube 24 can be opened. A structure suitable for discharging the excavation slime can be obtained.

That is, in the embodiment shown in FIG. 1, the swivel 32 is provided with the discharge port 36 for the excavation slime B.
In the case of the present embodiment, the outlet 36 is not always necessary, and the rear end of the outer tube 24 is opened, and the centrifuge 4 is opened.
6 only needs to be supported coaxially with the inner tube rod 22.

This can be considered as follows. That is, in the case of the embodiment shown in FIG. 1, since the air bubbles F are used as the cooling medium A, even if the discharge port 36 that communicates with the discharge passage 30 in a bent state is provided,
Due to the viscosity of the bubbles F, the excavation slime B can be discharged smoothly.

However, when drilling water or air is used as the cooling medium, if such a bent discharge port 36 is provided, the excavation slime B stagnates at the bent portion, which becomes an obstacle to discharge.

Further, in the case of the present embodiment, the power transmission portion 56 includes a stepped portion 58 provided on the inner peripheral surface of the casing shoe 54 screwed and connected to the tip of the outer tube 24, and a drill bit 20. The convex portion 6 provided on the outer peripheral surface of the
0, and the outer tube 24 can be inserted into the drilled hole D by a forward pulling method with a simple structure.

[0054]

As described above in detail in the embodiments,
ADVANTAGE OF THE INVENTION According to the large diameter drilling method concerning this invention, discharge of excavation slime is performed smoothly, without damaging the ground, and the working environment is not deteriorated.

[Brief description of the drawings]

FIG. 1 is a cross-sectional explanatory view of a construction state showing one embodiment of a large-diameter drilling method according to the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a cross-sectional explanatory view of a construction state showing an example of a conventional drilling method.

[Explanation of symbols]

 Reference Signs List 20 drilling bit 22 inner pipe rod 24 outer pipe 26 drifter 28 medium supply passage 30 discharge passage 32 swivel A cooling medium B drilling slime C ground D drilling E compressed air F bubbles

Continued on the front page (72) Inventor Masatomo Nakajima 2-15-2 Konan, Minato-ku, Tokyo Obayashi Corporation Tokyo headquarters Reference) 2D029 DA02

Claims (5)

[Claims] 1. An inner pipe rod equipped with a drill bit for drilling a large diameter drill hole, and an outer pipe accommodating the inner pipe rod therein, wherein a thrust, rotation, and impact are applied to the drill bit. When drilling a hole, the cooling medium is supplied to the drill bit from a medium supply passage provided inside the inner pipe rod, and the inner pipe rod and the outer pipe are drilled. Through a slime discharge passage provided between the drilling method, a drilling slime accompanying the drilling is discharged to the outside, and the outer pipe is inserted into the drilled hole. A large-diameter drilling method using entrained air bubbles. 2. The air bubbles are generated by mixing a foaming agent mixture and compressed air, and the air bubbles are generated immediately before or inside the medium supply passage. The large diameter drilling method described. 3. Mixing an antifoaming agent with the drilling slime,
3. The method according to claim 1, wherein the bubbles are eliminated.
The large diameter drilling method described. 4. A large power transmission device according to claim 1, wherein a power transmission portion such as the thrust is provided at a distal end side of the outer tube, and the outer tube is inserted into the drilled hole by a forward pulling method. Drilling method. 5. The power transmission part is provided on an inner peripheral surface of a casing shoe screwed and connected to a tip of the outer pipe, and is provided on an outer peripheral surface of the drill bit, and the power transmission part is provided on the step part. The large-diameter hole drilling method according to claim 4, wherein the large-diameter hole drilling method comprises a contacting convex portion.