JPH11200750A - Excavation bit for winding hole and execution method using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set an anchor even if the thickness of an anchorage layer is insufficient and soft. SOLUTION: A hole widening blade 23 urged so as to project a blade edge by a spring is provided on the side part of an inner bit 12 movably fitted in an outer bit 11. After the outer bit 11 and the inner bit 12 are attached to an outer casing 14 and the edge of an inner rod 22 inserted in the casing 14 to perform excavation, the diameter of a fixing part is large and the anchor of large fixing force can be set by projecting the inner bit 12 from the outer bit 11 and projecting the hole widening blade 23 to be bore. Even if the thickness of an anchorage layer is insufficient and soft, an anchor can be set.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an excavating bit for forming an anchor having a large tip diameter and a construction method using the bit.

[0002]

2. Description of the Related Art Forces acting on foundations and tunnels of civil engineering structures and underground structures, protected areas and scenic construction works on the "paste" side of the ground, or earth retaining walls associated with excavation of the ground (earth pressure, (Water pressure) is installed.

[0003] This anchor is installed, for example, as shown in Fig. 9 (1) A bit 2 is attached to the tip of a rod 1 and drilled by boring. (FIG. 9A). (2) After excavation is completed, cement milk 3 is injected and filled,
The steel wire 4 is inserted (FIG. 9B). (3) Pull out the rod (FIG. 9 (c)). (4) A screw shaft and a wedge are attached to the steel wire 4, and the support plate 5 and the anchor plate 6 are installed (FIG. 9D). Then, after the cement milk 3 is hardened, the steel wire 4 is tightened to tighten the whole, brought into close contact with the soil, and fixed by the frictional force.

Therefore, in the design of the anchor, for example,
The resultant force such as earth pressure and water pressure is predicted, and the fixing unit 7 is designed so as to obtain a frictional force opposing the predicted resultant force.

More specifically, as shown in FIG. 9D, the anchor is composed of a fixing portion 7 that generates a frictional force with the soil and a free length portion 8 extending to the fixing portion 7. La and the drilling diameter D are calculated using the peripheral frictional force characteristics τ according to the characteristics of the formation.

However, there are cases where the above-mentioned design cannot cope. For example, when the thickness of the fixing layer is insufficient or when the frictional force of the fixing layer itself is small. In such a case, the anchoring force is insufficient and the anchor is pulled out.

One method of solving this problem is to increase the surface area by increasing the drilling diameter D so that the fixing force can be secured even when the thickness of the fixing layer is insufficient or the frictional force of the fixing layer is small. It is possible to do.

[0008]

However, in the method of increasing the hole diameter as described above, an excessive hole is required even in the free length portion from the hole to the fixing portion. Therefore, there is a problem that a collapse accident is likely to occur near the expanded hole. Further, there is a problem that the cost is increased due to the excessive drilling.

An object of the present invention is to make it possible to fix an anchor without excessive drilling and an accompanying increase in cost even when the thickness of the fixing layer is insufficient or the frictional force is small. It is.

[0010]

In order to solve the above-mentioned problems, according to the present invention, an outer bit attached to a tip of an outer casing and an inner bit attached to a tip of an inner rod are provided. A digging blade is formed around the periphery of the inner bit, and the inner diameter is formed to a size that allows the inner bit to be inserted into the inner bit so as to be able to advance and retreat, and a water passage is formed between the inserted inner bit and the outer bit. The bit has a through hole formed at the tip end thereof, which communicates with the excavating blade and the inner rod, and a passage communicating with a water passage formed between the outer bit. The hole blade is rotatably mounted at the rear with the blade edge at the tip end side, and is urged to extend the blade edge by a spring. It was adopted formed.

By adopting such a configuration, when the inner bit is inserted into the outer bit, the hole-expanding blade is pressed against the inner periphery of the outer bit or the outer casing and closed.

When the inserted inner bit is advanced from the tip of the outer bit, the hole-expanding blade is released and extended by a spring. For this reason, by drilling with the overhanging blade, an expanded anchor hole can be formed.

Further, the overhanging blade has a rear portion rotatably attached thereto, and an outer bit is fitted to the advanced inner bit from the rear, or the extended inner bit is retracted to form the outer bit. Can be closed by fitting.

On the other hand, the water injected into the inner rod is jetted into the through hole of the inner bit. At this time, the passage formed in the inner bit can introduce the jetted water into a water passage formed between the outer casing and the inner rod, and discharge the slime out of the hole together with the water.

At this time, after the outer bit and the inner bit are attached to the outer casing and the tip of the inner rod inserted into the outer casing and excavation is performed, the inner bit is advanced from the outer bit, and the hole-extending blade is extended. By adopting the configuration of excavation by excavation, the diameter can be increased by the overhanging blade, so that a fixing portion having a large fixing force due to the diameter expansion can be formed.

Further, after the inner bit is advanced and excavation is performed, the outer casing is advanced, the inner bit is fitted from the rear, and the inner bit is taken out. The inner bit can be pulled out while preventing the collapse of the hole wall by the extended outer casing because the extended hole blade can be closed by being fitted from the outer casing.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 to FIG. 4 show a drill bit 10 according to a first embodiment of the present invention.

The drilling bit 10 for expanding holes includes an outer bit 11 and an inner bit 12.

The outer bit 11 has a cylindrical shape, and has a plurality of excavating tips 13 attached as excavating blades around the distal end thereof. On the other hand, a connection portion 15 is provided around the rear end. As shown in FIG. 2, the connecting portion 15 is provided with a step and is formed in such a size that the tip of the outer casing 14 can be fitted therein, and can be connected to the fitted out casing 14.

The inner diameter of the outer bit 11 is
The inner bit 12 is formed in such a size that the inner bit 12 can be inserted and retracted freely.
A water passage 16 is formed between the outer bit 11 and the outer bit 11.

In this case, the inner bit 12
Has an outer diameter that is inserted into the inner diameter of the outer casing 14 that is formed to have substantially the same diameter as the inner diameter of the outer bit 11,
The inside is hollow 21. A plurality of excavating tips 13 are attached to the tip as excavating blades. In addition, a through hole 17 and a passage 18 are formed radially at the distal end.

The through hole 17 penetrates through the hollow 21 of the inner bit 12 and communicates with an inner rod 22 connected to the rear end. The passage 18 extends rearward and communicates with the water passage 16 formed between the outer bits 11.

On the other hand, as shown in FIGS. 1, 2 and 4, a groove 24 is formed in the side portion, in which a hole-enlarging blade 23 is rotatable by a pin 26 with a cutting edge 25 as a tip. Installed. A spring 27 is attached to the pin 26.
Are attached, and as shown in FIG.
Energize to overhang.

On the other hand, a connection 28 with the inner rod 22 is provided at the rear of the inner bit 12. The connecting portion 28 is formed to have a step size so that the tip of the inner rod 22 can be fitted therein.

This embodiment is configured as described above.
Next, a method for constructing an anchor using the drilling bit 10 for hole drilling will be described.

In this case, in this embodiment, the operation of the bit 10 will be described by describing a case where the anchor is installed on a steel pipe pile 30 provided as an earthwork wall as shown in FIG.

First, the guide pipe 31 is attached to the steel pipe pile 30 by welding at the excavation place of the anchor hole. And
A water stop box 32 is attached to the guide tube 31.

The guide tube 31 and the water stop box 32 are conventionally used for anchor excavation, and the outer casing 14 is inserted into the water stop box 32 to be supported.

After the installation of the guide tube 31 and the water stop box 32, the outer casing 14 and the inner rod 22
Attach the outer bit 11 and the inner bit 12 to the tip of. At this time, the inner bit 12 is
3 is closed and fitted into the outer bit 11.

Then, the outer casing 14 and the inner rod 22 are attached to a water swivel 34 and a cleaning adapter 35 provided at the tip of a shank rod 33 of a boring machine, and inserted into the water stop box 32. Excavate. At this time, the inner rod 2
The slime is discharged out of the hole by injecting water into the hole 2 and ejecting the water from the through hole 17 of the inner bit 12 and sucking the return water from the passage 18.

Excavation of the free length portion 8 is performed with the inner bit 12 inserted in this manner. When this excavation ends,
The outer bit 11 is stopped. Then, only the inner rod 12 is advanced. Then, the restriction of the outer casing 14 by the hole-enlargement blade 23 of the inner bit 12 is released, and the hole 27 is slightly lifted by the spring 27.

At this time, whether or not the hole expanding blade 23 is opened can be confirmed by, for example, the insertion length of the inner rod 22 and the rotational resistance of the boring machine. In other words, the insertion length becomes longer because it has advanced from the outer casing 14. In addition, the rotation resistance is determined by
Increases in contact with sediment. Thus, it can be confirmed by the insertion length and the increase in resistance.

At this time, by opening the inner rod 22 (moving the rod forward and backward), the opening of the hole expanding blade 23 can be ensured.

Then, with the hole-expanding blade 23 extended,
Drill holes as shown in FIG. Also in this case, by pouring the water into the inner rod 12, the slime can be discharged out of the hole together with the drilling water via the outer casing 14. By drilling in this way, the fixing portion 7 having an enlarged diameter can be formed.

When the excavation of the fixing section 7 is completed in this way, the inner bit 12 is taken out, but cannot be taken out when the widening blade 23 is overhanging. Therefore, the outer casing 14 is advanced and fitted to the inner bit 12 as shown in FIG. Then, the hole-expanding blade 23 of the inner bit 12 whose rear end is fastened by the pin 26 is pressed by the outer bit 11 from behind and closed. Therefore, the inner rod 22 can be pulled out by the boring machine. At this time, since the hole wall is secured by the outer casing 14, the inner bit 12 can be taken out while securing the hole wall.

When the removal of the inner bit 12 is completed, a grout hose is inserted into the outer casing 14 and the cement milk 3 is injected. And PC steel wire 4
Is inserted, the outer casing 14 is pulled out, and the grouted cement milk 3 is cured and cured. After a lapse of a predetermined curing period, the PC steel wire 4 is tensioned, and an anchor plate (pedestal, abdomen, backing material) 5 and the like are installed.

The anchor thus constructed has a large fixing portion 7, so that a high fixing force can be obtained.

Accordingly, earth retaining work can be performed even in a place where a sufficient fixing length La cannot be secured due to a shortage of the fixing layer thickness of the formation and a shortage of peripheral frictional force.

Further, since only the diameter of the fixing portion 7 is increased in this manner, collapse of the hole is less likely to occur. Further, pulling out of the inner bit 12 is performed in the outer casing 14.
The hole can be formed while securing the hole, so that the collapse of the hole can be prevented even in a soft stratum, and the anchor can be installed.

Next, as a second embodiment, a construction method for a soft ground layer, particularly a sand layer, will be described.

In this construction method, the fixing section 7 is excavated while the outer casing 14 secures a hole wall.

That is, the excavation of the free length portion 8 is performed by exposing the outer bit 11 and the inner bit 1 to the distal ends of the outer casing 14 and the inner rod 22 as in the first embodiment.
2 and the outer casing 14 is used to prevent collapse. Next, the inner rod 22 is advanced and the inner bit 12 is advanced from the outer bit 11 as shown in FIG. Then, the hole-expanding blade 23
As described in the first embodiment, the outer casing 1
The restriction by 4 is released, and it is slightly lifted by the spring and opened by resistance of the earth and sand at the time of advance.

At this time, it is confirmed whether or not the hole-expanding blade 23 is open, as in the first embodiment, that the insertion length is longer than that of the outer casing 14. It can be confirmed from the fact that the resistance increases.

Further, by performing the etching of the inner rod 22, the opening of the hole-expanding blade 23 can be reliably performed.

Then, the outer bit 11 and the inner bit 12 are simultaneously advanced and excavated in a state where the hole-expanding blade 23 is extended, thereby forming the fixing portion 7 having an enlarged diameter.

By excavating the outer bit 11 and the inner bit 12 at the same time as described above, a hole wall can be secured in the outer casing 14, so that the fixing portion 7 can be drilled even in a soft ground layer.

At this time, the slime can be discharged to the ground by pouring water into the inserted inner rod 22 and digging while pouring water.

When the excavation of the fixing portion 7 is completed, as described in the first embodiment, the outer casing 14 is advanced and the outer bit 11 is fitted to the inner bit 12 from behind, as described in the first embodiment. ,
Since the widening blade 23 of the inner bit 12 can be closed, the inner rod 22 can be pulled out by a boring machine.

In this manner, the outer casing 1
The inner bit 12 can be taken out while the hole wall is secured by 4.

When the removal of the inner rod 22 is completed, as described above, the outer casing 14
A grout hose is inserted therein, cement milk 3 is injected, grout is applied, and then a PC steel wire 4 is inserted.

Then, the outer casing 14 is connected to a boring machine and pulled out to cure and cure the grouted cement milk. After a certain curing period, PC
The steel wire 4 is tensioned, and an anchor plate (pedestal, upset, backing material) 5 and the like are installed.

Since the anchor constructed in this way can increase the diameter of the fixing portion 7, a sufficient fixing force can be obtained without increasing the length of the fixing portion 7. At that time, the hole can be made small in diameter, so that a collapse accident can be made hard to occur.

Therefore, earth retaining work can be performed even in a place where a sufficient fixing force cannot be secured due to a shortage of the fixing layer thickness or a shortage of peripheral frictional force.

As described above, even in a soft formation, the hole can be expanded by the inner bit 12 while the hole wall is secured by the outer casing 14, so that the anchor can be easily installed.

[0056]

According to the present invention, since an anchor having a large anchoring portion diameter can be formed as described above, it is possible to construct an anchor body even in a place where the soil layer is thin and in poor conditions. The construction range of the body can be expanded. Further, in the conventional anchor body, it is possible to reduce the length of the anchoring portion and to reduce excessive digging and drilling work, and it is possible to construct a reasonable anchor body while improving the quality of the anchor body.

[Brief description of the drawings]

FIG. 1 is a perspective view of a first embodiment.

FIG. 2 is a longitudinal sectional view of the first embodiment.

FIG. 3 is a plan view of the first embodiment.

FIG. 4 is a longitudinal sectional view of a main part of the first embodiment.

FIG. 5 is an operation explanatory view of the first embodiment.

FIG. 6 is an operation explanatory view of the first embodiment.

FIG. 7 is an operation explanatory view of the first embodiment.

FIG. 8 is an operation explanatory view of the second embodiment.

FIG. 9 is a diagram illustrating the operation of a conventional anchor installation.

[Explanation of symbols]

 Reference Signs List 10 drilling bit for drilling 11 outer bit 12 inner bit 13 tip 14 outer casing 15 connecting portion 16 water passage 17 through hole 18 passage 22 inner rod 23 drilling blade 25 cutting edge 26 pin 27 spring

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[Procedure amendment]

[Submission date] December 21, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction contents]

[0010]

[Means to solve the problems] In order to solve the above problems, 請
In Motomeko 1, the outer bit attached to the distal end of the outer casing, mounting et the outer bit
Consisting of an inner bit attached to the tip of an inner rod extending from the tip of the outer casing ,
The outer bit is cylindrical and has a cutting edge formed at the periphery of the tip, and the inner diameter is formed to be large enough to allow the inner bit to be inserted into the outer bit so that the inner bit can be advanced and retracted. A channel is formed,
On the other hand, the inner bit has a through hole formed at the distal end thereof and a through hole communicating with the inner rod and a passage communicating with a water passage formed between the outer bit,
A hole-expanding blade is attached to the side portion, and the hole-expanding blade has a structure in which the blade edge is rotatably mounted with the blade edge at the tip end side, and the blade edge is biased by a spring to project the blade edge. .

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction contents]

[0011] By adopting such a configuration, Lee
Inner bit attached to the tip of the inner rod
Is inserted into the outer casing.
-It is pressed against the inner periphery of the casing and the hole-enlargement blade closes.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

[0012] The outer and inner bit that is the inserted through
From the end of the outer casing with the bit attached
When the inner rod is extended and advanced, the hole-expanding blade is released and extended by a spring. Therefore, in this state
If drilling is performed by extending the inner rod, an anchor hole that is expanded from this point can be formed.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

At this time, after excavating by attaching the outer bit and the inner bit according to the first aspect to the outer casing and the tip of the inner rod inserted through the casing , the inner rod is extended from the outer casing. by adopting the configuration of performing drilling overhanging the reaming blades, it is possible to form a reamed with anchor holes for the fixing unit in overhanging拡経.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

After the inner rod is extended and excavated, the outer casing is advanced, the inner bit is fitted from the rear, and the inner bit is taken out . Energized and times
The piercing blade, which is movably attached, can be closed by fitting the outer casing from behind, so that the inner casing can be closed with the advanced outer casing while preventing the collapse of the hole wall. Can be pulled out.

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction contents]

Then, with the hole-expanding blade 23 extended,
As shown in FIG. 6, the inner rod 22 is
A hole is drilled by extending from the tip of the thing 14 . Also in this case, by pouring the water into the inner rod 22 , the slime can be discharged to the outside of the hole together with the drilling water via the outer casing 14. By drilling in this way, the fixing portion 7 having an enlarged diameter can be formed.

[Procedure amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0043

[Correction method] Change

[Correction contents]

That is, the excavation of the free length portion 8 is performed by exposing the outer bit 11 and the inner bit 1 to the distal ends of the outer casing 14 and the inner rod 22 as in the first embodiment.
2 and the outer casing 14 is used to prevent collapse. Next, as shown in FIG. 8, the inner
-Extend the rod 22 from the tip of the outer casing 14
Then, the inner bit 12 is advanced. Then, as described in the first embodiment, the restriction by the outer casing 14 is released, and the hole expanding blade 23 is slightly lifted by the spring and opened by the resistance of the earth and sand at the time of advance.

Claims (3)

[Claims] An outer bit is attached to a tip of an outer casing and an inner bit is attached to a tip of an inner rod. The outer bit has a cylindrical shape, a cutting edge is formed around the tip, and the inner diameter is the inner diameter. The bit is formed in a size that allows the bit to be freely inserted and retracted, and a water passage is formed between the inserted inner bit and the outer bit, while the inner bit communicates with the excavating blade and the inner rod at the tip. A passage communicating with a water passage formed between the through hole and the outer bit is formed,
A hole-expanding blade is attached to the side portion, and the hole-expanding blade is rotatably attached to a rear portion thereof with a blade edge at a tip portion side, and is biased by a spring to project the blade edge. Drilling bits for drilling holes. 2. After excavating by attaching the outer bit and the inner bit according to claim 1 to a tip of the outer casing and an inner rod inserted into the casing, the inner bit advances from the outer bit, A construction method in which excavation is performed by overhanging the hole-expanding blade. 3. After the inner bit according to claim 2 is advanced and excavated, the outer casing is advanced,
An installation method in which the inner bit is fitted from the rear and the inner bit is taken out.