JP2004052437A - Double pipe boring device used in pressurized water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a boring device capable of preventing the intake of excessive slime into a casing when boring under pressurized water. <P>SOLUTION: This boring device is provided with a double pipe formed of the casing 3 having a ring bit 2 at the tip thereof and an inner rod 4 for supplying boring water. A movable bit 6 formed of a slime flow passage 8 in the periphery thereof and hit by the inner rod 4 is movably fitted in the inner periphery of the tip of the casing 3. A stopper 7 for opening/closing the slime flow passage 8 is provided in the rear of the movable bit 6. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a double pipe drilling device, and more particularly, to a drilling device used under pressured water.
[0002]
[Prior art]
For example, when creating a ground anchor, a drilling step is first performed. At this time, if the construction position of the anchor is under the pressurized water, countermeasures against the backflow of the pressurized water during excavation are required. There are a single-pipe method and a double-pipe method in the drilling method, and both have advantages and disadvantages in the case of excavation under pressurized water.
[0003]
That is, in the single pipe system, the drilling water is supplied through the inside of the casing, and discharged outside the hole through the outside. In this case, since a casing with a check valve is used as the tip bit, there is an advantage that slime does not flow into the casing due to the water to be pressurized. On the other hand, when the soil is sand or gravel, if the drilling length is long (for example, 15.0 m or more), a long time is required for drilling, or drilling becomes impossible.
[0004]
In the double pipe system, the drilling water is supplied through the inside of the inner rod, and is discharged outside the hole through the space between the casing and the inner rod. In the case of this double pipe system, long holes can be drilled even when the soil is sand or gravel, and there is an advantage that drilling does not take much time. However, when the pressure difference of the pressurized water is large, excessive slime flows backward during drilling and during the desorption operation of the casing, and the slime accumulates in the casing. When slime is stored in such a casing, insertion of tendon (tensile material) or grouting after drilling becomes impossible.
[0005]
[Problems to be solved by the invention]
The present invention has been made based on the technical background as described above, and achieves the following objects.
An object of the present invention is to provide a drilling device capable of preventing excessive slime from being taken into a casing when drilling under pressurized water.
[0006]
Another object of the present invention is to prevent the backflow of pressurized water at the time of demounting the casing in addition to the above-described prevention of the intake of excess slime, and furthermore, to efficiently drill holes as in the ordinary double pipe system. It is an object of the present invention to provide a drilling device that can perform the drilling.
[0007]
[Means for Solving the Problems]
The present invention employs the following means to achieve the above object.
That is, the present invention is a drilling device provided with a double pipe of a casing having a ring bit at the tip and an inner rod inserted into the casing and supplying drilling water,
A slime flow path is formed on the outer circumference of the distal end portion of the casing, and a movable bit hit by the inner rod is fitted movably in the axial direction, and the slime flow path is provided behind the movable bit. A double-pipe drilling apparatus for pressurized water is provided with a stopper that opens and closes.
[0008]
The movable bit may have a polygonal cross section. In this case, a gap formed between the outer circumference of the bit and the inner circumference of the casing constitutes the slime flow path. The movable bit may have a circular cross section. In this case, a hole constituting the slime flow path is formed on the outer periphery.
[0009]
At the time of drilling, the movable bit is hit by the inner rod against the pressurized water acting on the front surface of the movable bit. Earth and sand are cut by the impact of the movable bit. In addition, the movable bit advances and separates from the stopper due to the impact of the movable bit. Thereby, the slime flow path is opened, and the slime is taken into the casing. The slime flows into the casing only when the movable bit is hit, so that excessive slime can be prevented from being taken in. When the impact of the movable bit is stopped, the movable bit retreats due to the pressure of the pressurized water and contacts the stopper, thereby closing the slime flow path. Therefore, the pressurized water does not flow through the slime flow path, and the backflow of the pressurized water at the time of attaching and detaching the casing can be prevented. Thus, the movable bit functions not only as a bit for cutting earth and sand, but also as a valve for controlling the inflow of slime and pressurized water.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment in which the drilling device according to the present invention is applied to drilling for ground anchor formation. In the ground anchor construction work, a water stop box 51 is installed on the retaining wall 50, and a hole (anchor hole) is formed from the water stop box 51 by the hole drilling device 1.
[0011]
FIG. 2 is an axial sectional view showing details of the drilling device 1, and FIG. 3 is a view taken along line AA of FIG. 2. The drilling device 1 includes a casing 3 (drill pipe) having a ring bit 2 at a tip, and an inner rod 4 inserted into the casing 3 to supply drilling water. An inner bit 5 is attached to a tip of the inner rod 4. As will be described later, the inner bit 5 does not directly perform a drilling operation, but functions as a hammer.
[0012]
A movable bit 6 is fitted around the inner periphery of the distal end of the casing 3, and an annular stopper 7 is provided behind the movable bit 6. The movable bit 6 is axially movable in front of the stopper 7. As shown in FIG. 3, the movable bit 6 has a hexagonal cross section having a circle slightly smaller than the inner diameter of the casing 3 as a circumscribed circle. Are formed with a plurality (six) of slime channels 8. As shown in FIG. 4, these slime channels 8 open when the movable bit 6 moves forward and separates from the stopper 7 (FIG. 4A), and the movable bit 6 retreats and comes into contact with the stopper 7. At that time (FIG. 6 (b)).
[0013]
Next, the operation of the drilling device will be described. The movable bit 6 is attached to the front end of the casing 3, and the rear ends of the casing 3 and the inner rod 4 are connected to a boring machine (not shown), and the hole is drilled by rotating the ring bit 2 and hitting the movable bit 6. That is, while rotating the ring bit 2 via the casing 3, a striking force is applied to the inner bit 5 via the inner rod 4 to hit the movable bit 6. Drilling water for discharging the slime is discharged from the inner bit 5 through the inner rod 4, and is discharged out of the hole through the space between the casing 3 and the inner rod 4.
[0014]
Here, assuming that the drilling position is under the pressurized water, as shown in FIG. 4A, in order to cut the earth and sand by the movable bit 6, the impact force against the pressure P of the pressurized water is required. Must be given to the movable bit 6. As a result, the movable bit 6 moves forward, the slime flow path 8 opens, and the slime is taken into the casing 3 by the pressurized water P as shown by the arrow S. The slime is discharged out of the hole by the drilling water discharged from the inner bit 5.
[0015]
On the other hand, as shown in FIG. 4B, when the inner bit 5 is retracted and the impact of the movable bit 6 is stopped, the movable bit 6 is retracted by the pressure P of the water to be pressurized, and comes into contact with the stopper 7 so as to contact the slime flow path. 8 is closed. As described above, the slime is taken in only when the movable bit 6 is hit to cut the earth and sand, and therefore, it is possible to prevent the taking-in of excessive slime in the hole. In addition, when the casing 3 is attached / detached (connected / disconnected), the state shown in FIG. 4B is closed, so that the slime flow path 8 is closed, so that the water to be pressurized is prevented from flowing back into the casing 3. be able to.
[0016]
As described above, the movable bit 6 functions not only as a bit for cutting earth and sand, but also as a valve for controlling the inflow of slime and pressurized water.
[0017]
FIG. 5 is a drawing similar to FIG. 3 showing another embodiment of the present invention. In this embodiment, the movable bit 16 has a circular cross section. A plurality of holes 18 are formed on the outer periphery of the movable bit 16 at intervals in the circumferential direction, and these holes 18 constitute a slime flow path. Other configurations are the same as those of the embodiment shown in FIGS. 2 and 3, and the operation thereof is also the same.
[0018]
The above embodiments are merely examples, and the present invention can take various aspects. For example, in the embodiments shown in FIGS. 2 and 3, the shape of the movable bit is hexagonal in cross section. However, in this embodiment, the shape may be polygonal in cross section, and is not limited to hexagon. Further, in the case of drilling under pressurized water, earth and sand are easily cut even if the front surface of the movable bit 6 is a flat surface, but a cutting tip may be provided on the front surface of the bit.
[0019]
Further, although the drilling device according to the present invention is of a double-pipe type, the inner rod 4 and the inner bit at the tip thereof do not directly drill, unlike the conventional double-pipe type. That is, the inner bit attached to the tip of the inner rod functions as a striker (hammer), and therefore, other than the bit can be used as long as it functions as a striker.
[0020]
【The invention's effect】
As described above, according to the present invention, the movable bit attached to the front end of the casing functions as a bit for cutting earth and sand, and also functions as a valve for controlling inflow of slime and pressurized water. Therefore, when drilling under the pressurized water, it is possible to prevent excessive slime from being taken into the casing and to prevent backflow of the pressurized water when the casing is detached. Further, efficient drilling can be performed similarly to the double pipe method.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a form in which a drilling device according to the present invention is applied to drilling for ground anchor formation.
FIG. 2 is an axial sectional view showing an embodiment of a drilling device according to the present invention.
FIG. 3 is a view taken along the line AA of FIG. 2;
FIG. 4 is an axial cross-sectional view for explaining the operation of the embodiment.
FIG. 5 is a view similar to FIG. 3, showing another embodiment.
[Explanation of symbols]
1: drilling device 2: ring bit 3: casing 4: inner rod 5: inner bit 6: movable bit 7: stopper 8: slime channel 16: movable bit 18: hole

Claims (3)

A drilling device provided with a double pipe of a casing having a ring bit at a tip and an inner rod inserted into the casing and supplying drilling water,
A slime flow path is formed on the outer circumference of the distal end portion of the casing, and a movable bit hit by the inner rod is fitted movably in the axial direction, and the slime flow path is provided behind the movable bit. A double-pipe drilling device under pressurized water, comprising a stopper that opens and closes. 2. The pressure receiving apparatus according to claim 1, wherein the movable bit has a polygonal cross section, and a gap formed between an outer periphery thereof and an inner periphery of the casing constitutes the slime flow path. Underwater double pipe drilling equipment. 2. The double-drilling apparatus according to claim 1, wherein the movable bit has a circular cross section, and a hole that forms the slime flow path is formed on an outer circumference of the movable bit. 3.

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