JP2924355B2 - Construction method of pile body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of constructing piles such as earth retaining piles and cast-in-place piles, and more particularly, to efficiently construct piles on hard ground through a gravel layer or soft ground and further on cobblestone layers. The present invention relates to a method for constructing a pile.

[0002]

2. Description of the Related Art Conventionally, a percussion method using a down-the-hole hammer has been used as a ground drilling method when a pile body such as an earth retaining pile or a cast-in-place pile is constructed on a hard ground or a cobblestone layer. However, in such a percussion method, when a soft ground or a gravel layer is present in the upper layer or in the middle of the hole to be drilled, the hole wall often collapses when the hammer is pulled out even if the hole is drilled to a predetermined depth. ,
It is difficult to make the hole independent.

[0003] Therefore, when a pile body is constructed on the ground consisting of both hard and soft layers, for example, Japanese Unexamined Patent Publication (Kokai) No. 2-13648 is used.
As described in Japanese Patent Application Laid-Open No. 9-206, a soft ground is excavated by a cutting-type excavator that excavates flat soft ground, for example, a full-turn all-casing excavator, and thereafter, a casing inserted into the ground. A method has been adopted in which a down-the-hole hammer is inserted into the inside of the tube and protruded from the tip of the casing tube, thereby piercing a hard ground or a boulder layer in a lower layer portion, and thereafter, a pile body is erected in the hole. Was.

[0004]

However, the above-described method of using the excavation by the casing tube and the drilling by the down-the-hole hammer is effective only for the stratum where the soft ground and the hard ground are clearly separated from each other at the top and bottom. Since the actual stratum often has a complex structure such as a layer of hard and soft layers alternately or a boulder layer in the middle of soft ground, it is still difficult to construct piles using the above method. There were many. The present invention has been made under such a background, and a pile body in which a desired hole can be easily formed and the pile body can be easily constructed even in the ground having a complicated structure in which both hard and soft layers are alternately present. The purpose is to provide a construction method.

[0005]

According to the present invention, there is provided a method for solving the above problems.
In order to achieve the object, a method of constructing a pile body according to the present invention
Is how to install piles on hard ground including soft ground.
Method, wherein a drilled body having a bit that can be radially expanded and contracted at the tip is inserted into a hollow casing tube, and the bit is projected from the tip of the casing tube to contact the ground. With the rotation of the perforated body
The resistance received from the ground expands the bit beyond the outer diameter of the casing tube, and in this state, pushes the bit into the ground to pierce the ground,
After inserting the casing tube into the perforated hole and following the bit, after the perforation to a predetermined depth is completed, the bit is reduced in diameter and then pulled into the casing tube to pull the perforated body into the perforated body. The casing tube is removed from the casing tube, and then a reinforcing member such as an H-shaped steel or a reinforcing bar is inserted into the casing tube. After that, the casing tube is vibrated and pulled out of the hole while the self-hardening material such as concrete is inserted into the hole. Characterized by injecting
I have.

[0006]

According to the construction method of the pile body as described above, for example,
By the perforated body consisting of down the hole hammer etc.
When drilling through hard ground including rock zones and boulders,
In conjunction with the drilling by the bit disposed at the tip of the drilling body, the casing tube following the bit sequentially covers the hole wall, so that the hard ground or the boulder layer is pierced by the bit and the soft ground is drilled. Or a gravel layer appears,
The casing tube prevents the soft ground and the gravel layer from collapsing at the hole wall. At this time, the rotation of the drill
With the resistance received from the ground, since the outer diameter of the bit is made to diameter on the outer diameter or the casing tube, hard
Insert the casing tube into the hole even if the ground is
In the soft ground and the gravel layer.
Since the insertion resistance of the sourcing tube can be reduced , there is no possibility that the hole wall will newly collapse due to the insertion resistance. In addition, since the casing tube is vibrated when it is removed, the casing tube can be easily and quickly extracted from the inside of the hole. In addition, since the self-hardening material such as concrete is injected at the time of the extraction, the reinforcing member previously inserted and the self-hardening material are integrally formed in the hole along with the extraction of the casing tube, thereby forming a pile body. As a result, a desired pile body is constructed.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of a method for constructing a pile according to the present invention; FIG. explain.

As shown in FIGS. 1 to 3, a piercing body used in this embodiment is a device 2 which receives the impact force of a hammer (not shown) and the rotational force of a hammer cylinder 1 driven by compressed air. On the bottom surface of the device 2, two shaft holes 2A and 2B are formed point-symmetrically with respect to the center of the device 2, and each of the shaft holes 2A and 2B is formed.
Bit shafts 3A and 3B are attached to the shafts A and 2B so as to be rotatable around the shaft and prevented from coming off in the axial direction.
Bits 5A and 5B having a substantially semicircular shape having substantially the same diameter as the device 2 at the distal end portions of A and 3B, and having a plurality of chips 4 implanted at the distal end surfaces thereof face the straight end surfaces 6A and 6B of each other. When the device 2 is rotated in the normal rotation direction (X direction in FIG. 3), the bit shafts 3A and 3B are
One end of each of the bits 5A, 5B protrudes from the outer peripheral surface of the device 2 by a predetermined amount, and at this time, the straight end surfaces 6A, 6B of both bits are eccentric from the center of the device 2 so as to abut each other. It is configured.

The perforated body is inserted into a hollow cylindrical casing tube 9 so as to be movable in the axial direction. A reduced-diameter tube 11 that engages with a large-diameter portion 10 formed on the outer peripheral surface of the device 2 is integrally fixed to the inner periphery of the distal end portion of the casing tube 9 by welding or the like.

Here, when the bits 5A and 5B are projected from the tip of the casing tube 9 and the device 2 is rotated in the normal rotation direction X by the hammer cylinder 1, as shown in FIG. The bits 5A and 5B stored in the small diameter state also rotate around the bit axes 3A and 3B due to the resistance caused by the perforation, and as a result,
As shown in FIG. 3, the straight end faces 6 of the bits 5A, 5B
One ends of A and 6B protrude from the outer periphery of the casing tube 9 by a predetermined amount. Then, in this state, the straight end faces 6A, 6B
Of the bits 5A, 5B
Stops around the bit axes 3A and 3B.

Next, a method of constructing a pile body using the above-described perforated body will be described with reference to FIGS.

In this embodiment, first, as shown in FIG. 4, the bits 5A and 5B are projected from the tip of the casing tube 9, and in this state, the device 2 is rotated in the normal rotation direction X, and a hammer (not shown) is used. An impact is applied to the perforated body in the axial direction of the casing tube 9. As a result, the bits 5A and 5B are pushed into the ground in a state where the diameter of the bits is larger than the outer diameter of the casing tube 9, and the ground 22
Are sequentially drilled by the chips 4 of the bits 5A and 5B to form predetermined holes 12.

Further, due to the impact given to the perforated body, the reduced-diameter tube 11 of the casing tube 9 comes into contact with the enlarged-diameter portion 10 of the device 2, whereby the impact force of the hammer is also transmitted to the casing tube 9. Moreover, the impact force is such that the reduced diameter tube 11 is larger than the enlarged diameter portion 10 in the casing tube 9.
Therefore, since the casing tube 9 is located on the tip side, the casing tube 9 is applied only in the direction of pushing the casing tube 9 into the ground. Therefore,
Due to the impact force of the hammer and the weight of the casing tube 9, the casing tube 9 bites into the hole 12 successively following the bits 5A and 5B.
The hole wall 12a is covered with the casing tube 9 immediately after the formation. Therefore, collapse of the hole wall 12a is effectively prevented. In this case, since the hole 12 is formed to have a slightly larger diameter than the outer diameter of the casing tube 9, the resistance when the casing tube 9 bites into the ground 22 is small. Therefore, there is no possibility that a new hole wall collapse occurs.

As for the earth and sand, gravel and the like generated in the above-described drilling process, compressed air which is discharged when a hammer piston (not shown) falls in the hammer cylinder 1 is provided on the bottom surface of the device 2. By being blown out from the air holes 7A and 7B, it is discharged from the tip of the perforated body, and then moves through the discharge groove 8 provided in the device 2 into the casing tube 9, from which it is further discharged to the ground. It is being done.

After the drilling by the bits 5A and 5B reaches a predetermined depth, the application of the impact by the hammer is stopped, and the rotation direction of the hammer cylinder 1 is reversed so that the bits 5A and 5B are rotated in the direction opposite to the normal rotation direction X. Rotate in the direction. Thereby, the bits 5A and 5B rotate around the bit shafts 3A and 3B in the direction opposite to the direction at the time of drilling, and the bits 5A and 5B are reduced in diameter to be smaller than the inner diameter of the casing tube 9 as shown in FIGS. .

After the bits 5A and 5B have been reduced in diameter, the perforated body is pulled up toward the ground and removed from the inside of the casing tube 9 as shown in FIG. Then, as shown in FIGS. 7A and 7B, a reinforcing member 13 such as an H-shaped steel is inserted into the hollow casing tube 9. In addition,
The reinforcing member 13 is appropriately selected as necessary, such as a rebar cage, in addition to the H-shaped steel.

After the reinforcing member 13 is installed, the upper end side of the casing tube 9 is connected to a lifting means 14 such as a crane as shown in FIG. Here, a vibration means 15 such as a vibratory hammer is interposed between the lifting means 14 and the casing tube 9. On the other hand, a grout pump (not shown) for injecting a self-hardening material 16 such as concrete into the hole 12 is provided on the upper end side of the hole 12.

After the above preparation is completed, the self-hardening material 16 is injected into the casing tube 9 while the casing tube 9 is lifted upward by the lifting means 14 while vibrating the casing tube 9 by the vibration means 15. As a result, the casing tube 9 is gradually pulled out from the hole 12 to expose the hole wall 12 a, and immediately thereafter, the hole wall 12 a is covered with the self-hardening material 16. Then, the self-hardening material 16 is cured and integrated with the reinforcing member 13, so that the holes 12 are formed.
A strong pile 17 is formed on the hole wall 1 and
2 is prevented from collapsing. In this case, since the casing tube 9 is extracted while being vibrated, the casing tube 9 can be easily and quickly extracted from the inside of the hole 12. In addition, since the self-hardening material 16 such as concrete is injected at the time of the removal, the casing tube 9 is removed.
By completing the extraction, the desired pile 17 can be obtained immediately.

As described above, according to the present embodiment,
In the process of drilling the ground 22 with the bits 5A and 5B,
a is successively covered with the casing tube 9, so as shown in FIGS. 6 to 8, for example, even in the case of the perforation of the ground 22 having a complicated structure in which the hard ground 22 a and the soft ground 22 b are mixed, even in the soft ground 22 b The desired hole 12 can be easily formed by preventing collapse of the hole wall 12a. On the other hand, after completion of the drilling, the pile 17 is formed while the collapse of the hole wall 12 is prevented by the vibration and extraction of the casing tube 9 and the injection of the self-hardening material 16. Since the construction of 17 is also completed, the desired pile body 17 can be constructed easily and quickly.

When the pile 17 is formed on the ground 22 in which the hard ground 22a and the soft ground 22b are mixed according to the present embodiment, a slight gap is formed between the inner diameter of the hole 12 and the outer diameter of the casing tube 9. Because of the difference, as shown in FIG.
b may collapse slightly to form a reduced diameter portion 17a in the pile body 17. However, in such a case, since the reduced diameter portion 17a functions as a retaining member, an effect that the pile 17 is held more firmly is obtained, which is more convenient for the pile 17. In particular, the soft ground 22b is
If there are a plurality of locations along the axial direction of
This is more effective because the retaining member is provided at a number of places.

In this embodiment, the bit 5A, 5B divided into two parts is provided at the tip of the drilling body. However, the present invention is not limited to this. For example, as shown in FIG. 5A, 5B, and 5C may be used. Further, the configurations of the perforated body and the casing tube 9 are merely examples, and these can be appropriately changed as necessary.

[0022]

As described above, according to the present invention, drilling is performed on hard ground including a hard rock zone and a boulder layer.
When drilling, the bit provided at the tip of the drill
Resistance from the ground along with the
The diameter is expanded to the outer diameter of the
Since the hole wall at the bit due to the ground drilling process were Yuku covered with successive casing tube, even hard ground Description
The casing tube can be easily inserted into the hole
In addition, even if a soft ground or a gravel layer appears on the way, the collapse of the hole wall can be prevented and a desired hole can be easily formed. On the other hand, after the drilling is completed, the pile body is formed while preventing the collapse of the hole wall by vibrating and removing the casing tube and injecting the self-hardening material, and the completion of the removal of the casing tube completes the desired construction. A pile is obtained. Therefore, according to the present invention, an excellent effect that a desired pile body can be easily and quickly constructed even on a ground having a complicated structure in which a hard ground and a soft ground are mixed is obtained.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a perforated body used in one embodiment of the present invention.

FIG. 2 is a front view showing the bit shown in FIG. 1 in a reduced diameter.

FIG. 3 is a front view showing the bit shown in FIG. 1 in an enlarged state.

FIG. 4 is a side sectional view showing a perforation process in one embodiment of the present invention.

FIG. 5 is a side sectional view showing a state in which perforation is completed in one embodiment of the present invention.

FIG. 6 is a side sectional view showing a punching body withdrawing process in one embodiment of the present invention.

FIGS. 7A and 7B are diagrams showing a reinforcing member inserting process in one embodiment of the present invention, wherein FIG. 7A is a diagram of the inside of the casing tube viewed from the upper end side, and FIG. 7B is a side sectional view of the casing tube in the axial direction.

FIG. 8 is a view showing a process of pulling out a casing tube in one embodiment of the present invention.

FIG. 9 is a diagram showing a modification of a bit.

[Explanation of symbols]

 5A, 5B, 5C Bit 9 Casing tube 12 Hole 12a Hole wall 13 Reinforcement member 16 Self-hardening material 22 Ground

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-55-23247 (JP, A) JP-A-5-71285 (JP, A) JP-B-57-25688 (JP, B2) (58) Field (Int.Cl. ⁶ , DB name) E02D 5/38 E02D 7/00 E21B 7/20

Claims (1)

(57) [Claims] Claims: 1. Pile for hard ground including soft ground
A method of constructing a body, wherein a drilled body having a bit that can be radially expanded and contracted at the tip is inserted into a hollow casing tube, and the bit is protruded from the tip of the casing tube to form the ground. Contact with
The above-mentioned bit by resistance received from the above-mentioned ground with rolling
The diameter of the casing tube is expanded to be equal to or larger than the outer diameter of the casing tube, and in this state, while pushing the bit into the ground to pierce the ground, insert the casing tube into the bored hole and follow the bit. After the drilling to the predetermined depth is completed, the bit is reduced in diameter and then drawn into the casing tube to remove the drilled body from the inside of the casing tube. A method for constructing a pile body, comprising inserting a reinforcing member such as a cage, and then injecting a self-hardening material such as concrete into the hole while vibrating the casing tube and pulling out the hole from the hole.