JPH0633455A - Bearing pile formation method and device therefor - Google Patents

Abstract

PURPOSE:To carry out drilling work efficiently and prevent the penetration of underground water or muddy water into a bearing pile under construction and hence form a strong concrete bearing pile. CONSTITUTION:A buried inner pipe 3 whose lower end is closed is concentrically inserted into an outer pipe 2 while an excavation blade mounted short pipe 8, which is mounted with an excavation blade 7 whose inner end projects inwardly, is removably connected to the lower end of the outer pipe 2. Both the outer pipe 2 and the inner pipe 3 are driven into the ground at a specified depth while rotating at least the outer pipe 2 and then the excavation blade mounted short pipe 8 is cut off from the outer pipe 2. The outer pipe 2 is pulled up from the underground while the short pipe 8 for the inner pipe and the inner pipe 3 are adapted to remain underground where concrete is filled up in the inner pipe 3.

Description

Detailed Description of the Invention

[0001]

2) The present invention relates to a method for constructing a support pile,
In particular, the present invention relates to a construction method for cast-in-place concrete support piles and an apparatus therefor.

[0002]

2. Description of the Related Art Construction methods for supporting piles of this type include the method of digging a ground with an earth auger and injecting cement mortar into the hole, or the casing with the tip closed to a vibrator or drop. After hammering into the hole and digging, there is a method to remove this casing and fill the hole with fresh concrete, but in both methods, groundwater and mud are easily mixed in cement mortar and fresh concrete, It is difficult to form a strong support pile, and in the latter method, the casing with the tip closed is driven directly into the ground, so the ground resistance received by the casing tip during driving the casing becomes extremely large. However, there was a problem that the drilling efficiency was poor and it took a very long time to perform the drilling work.

In view of the above-mentioned problems, the present invention is capable of efficiently performing a drilling operation and completely prevents the mixing of groundwater or mud into the support pile during construction, thus providing a strong concrete support pile. An object of the present invention is to provide a method and an apparatus for forming a support pile that can be formed.

[0004]

The method according to claim 1 of the present invention is a method for burying an inner pipe 3 having a closed lower end in an outer pipe 2.
Is inserted concentrically, and an excavating blade attaching short pipe 8 having an excavating blade 7 having an inner end of the blade portion protruding inward of the inner pipe 3 is detachably connected to a lower end of the outer pipe 2. In addition, after driving both pipes 2 and 3 to a predetermined depth in the ground while rotating at least the outer pipe 2 of the inner and outer pipes 2 and 3, the excavating blade mounting short pipe 8 is removed from the outer pipe 2. Separated, leaving the excavating blade mounting short pipe 8 and the inner pipe 3 left in the ground,
The outer pipe 2 is pulled up from the ground, and the inner pipe 3 is filled with concrete 25.

According to a second aspect of the present invention, a large number of excavated soil discharge holes 11 are provided in the outer pipe 2, and the space between the outer pipe 2 and the inner pipe 3 is used as the excavated soil introduction space 10. An air jet pipe 12 for jetting jet air from the excavated soil discharge hole 11 to the outside of the outer pipe 2 is provided in the space portion 10, and the jet air is jetted by the air jetting means 12 while the both pipes 2 and 3 are being driven. It is characterized in that it is ejected from each excavated soil discharge hole 11.

Further, the supporting pile forming apparatus according to claim 3 is
At the bottom of the machine frame 1, which is suspended from the reader so that it can be raised and lowered, the outer tube 2
And an embedded inner pipe 3 concentrically inserted in the outer pipe 2 and closed at the lower end thereof are hung and connected via detachable means 4 and 5, respectively, so as to be detachable from each other. At least the outer pipe 2 among the three is interlockingly connected to the rotation driving means 6 provided in the machine frame 1, and the inner end of the blade portion is protruded inside the inner pipe 3 at the lower end of the outer pipe 2. It is characterized in that the excavating blade mounting short pipe 8 to which 7 is mounted is detachably connected via a detaching means.

[0007]

EXAMPLES Examples will be described with reference to the drawings.
FIG. 1 shows a support pile forming apparatus for carrying out the method of the present invention. In this figure, reference numeral 1 is a machine frame, which is not shown in the drawing, but is guided by the side surface of the reader, and a lifting wire is interposed from the top thereof. Are suspended. In the lower part of the machine frame 1, a cylindrical outer pipe 2 and an embedded bottomed cylindrical inner pipe 3 concentrically inserted in the outer pipe 2 and closed at the lower end thereof are respectively attached / detached means 4 , 5 and are detachably connected to each other, and are integrally rotatable by the rotation driving means 6 provided in the machine frame 1, and the lower end of the outer tube 2 is provided with a blade portion 7a. An excavating blade attaching short pipe 8 to which a plurality of excavating blades 7 whose inner ends project to the inside of the inner pipe 3 are attached, is detachably connected via a detaching means 9. The outer pipe 2 is formed of a relatively thick steel pipe,
The inner pipe 3 is formed of a steel pipe or a fume pipe that is thinner than the outer pipe 2. In addition, in FIG. 1, 3a shows a lower end closing wall portion of the bottom portion of the inner pipe 3.

As shown in FIGS. 1 and 2, a space 10 for introducing excavated soil is formed between the outer pipe 2 and the inner pipe 3 to introduce excavated soil from the lower end thereof. In addition, a large number of excavated soil discharge holes 11 for discharging the excavated soil introduced into the excavated soil introducing space 10 to the outside of the outer pipe 2 are formed in a row at predetermined intervals in the vertical direction. In addition, they are provided in four rows at intervals of 90 degrees in the circumferential direction. An air jet pipe 12 (air jetting means) for jetting jet air from each of the excavated soil discharge holes 11 is provided in the excavated soil introducing space 10.
Are arranged in a fixed state along the inner surface of the outer pipe 2, and the air ejection pipes 12 are arranged along a group of excavated soil discharge holes 11 arranged in the vertical direction as shown by the broken line in FIG. A pipe 12 is provided so as to pass through the center of each excavated soil discharge hole 11, and a nozzle 12 for ejecting air is provided at the center of each excavated soil discharge hole 11.
a is projected outward.

The rotation driving means 6 is a pair of driving gears 14 and 14 of the pair of electric motors 13 and 13 mounted on the machine casing 1.
Is engaged with a transmission gear 16 provided in a rotation unit 15 rotatably supported in the center of the machine frame 1. The rotation of the electric motor 13 is rotated via the drive gear 14 and the transmission gear 16. Tell unit 15 this unit 1
The outer tube 2 and the inner tube 3 are integrally rotated by the rotation of 5. The outer tube 2 and the inner tube 3 are the rotary unit 15
And detachable means 4 and 5 which are respectively interposed between and so that they can be separated. Further, the upper end of each of the air ejection pipes 12 arranged along the inner surface of the outer pipe 2 is introduced into the rotary unit 15, and the upper end is connected to the swivel joint 17.

The attaching / detaching means 4, 5 and 9 will be described. The attaching / detaching means 4 is between the rotating unit 15 and the outer tube 2, and the attaching / detaching means 5 is between the rotating unit 15 and the inner tube 3. Further, the attachment / detachment means 9 is provided between the outer pipe 2 and the short pipe 8 for attaching the excavating blade, respectively. As shown in FIG. 3, the attachment / detachment means 4 includes an engagement pin 18 attached to the lower end of the rotary unit 15 and an engagement groove 19 formed by cutting out in a substantially T-shape at the upper end of the outer tube 2. The attachment / detachment means 5 is also composed of an engagement pin 20 similarly attached to the lower end of the rotary unit 15, and an engagement groove 21 formed by cutting out in a substantially inverted L shape at the upper end of the inner tube 3. The attaching / detaching means 9 includes an engaging pin 22 attached to the lower end of the outer tube 2.
And a substantially L-shaped engaging groove 23 similar to the engaging groove 21 of the attaching / detaching means 5 at the upper end of the excavating blade attaching short pipe 8. still,
Although only one each of these attaching / detaching means 4, 5, 9 is shown in FIG. 3, in reality, two or more attaching / detaching means are provided in the circumferential direction, for example, four at a time interval of 90 degrees in the circumferential direction. Has been.

Therefore, when the outer pipe 2 and the inner pipe 3 are driven, when the outer pipe 2 and the excavating blade mounting short pipe 8 and the inner pipe 3 are droopingly connected to the lower portion of the machine frame 1, as shown in FIG. As shown by the solid line, the engaging pin 18 of each attaching / detaching means 4
Is engaged in the inverted T-shaped engaging groove 19 from the vertical groove portion 19a and engaged with the engaging portion 19b at the right end, so that the outer tube 2
By connecting the engaging pin 20 of each attaching / detaching means 5 to the L-shaped engaging groove 21 from its vertical groove portion 21a and engaging with the engaging portion 21b at the right end. 3 is connected to the rotating unit 15. Further, the engaging pin 22 of each attaching / detaching means 9 is inserted into the L-shaped engaging groove 23, and the vertical groove portion 2 thereof is formed.
The excavating blade mounting short pipe 8 is connected to the lower end of the outer pipe 2 by engaging with the engaging portion 23b at the right end from 3a. Then, when the rotating unit 15 is rotated in the direction of arrow A in FIG. 3 in such a state, the outer tube 2 and the inner tube 3 are rotated while the connection state with the rotating unit 15 is maintained by the attaching / detaching means 4 and 5. In addition, the excavating blade mounting short pipe 8 is rotated by each attaching / detaching means 9 while maintaining the connected state with the outer pipe 2.
This enables excavation of the ground.

Further, as described above, the outer pipe 2 and the inner pipe 3 are connected to the rotary unit 15 via the attaching / detaching means 4 and 5, and the excavating blade mounting short pipe 8 is connected to the outer pipe 23 via the attaching / detaching means 9. In this state, the short pipe 8 for mounting the excavating blade is grounded on the ground, in fact, on the excavated soil at the bottom of the excavation hole, and the inner pipe 3 is suspended in suspension from the rotary unit 15. When the rotary unit 15 is rotated in the opposite direction from the above state in the opposite direction, that is, in the direction of arrow B in FIG. 3, the engaging pin 20 of the attaching / detaching means 5 rotates the rotary unit 15. Along with this, it moves to the left in FIG.
When it reaches 1c, it comes out of the engagement groove 21 through the vertical groove portion 21a, and as a result, the inner pipe 3 is separated from the rotary unit 15.

On the other hand, the engaging pin 18 of the attaching / detaching means 4 also moves in the same direction as the engaging pin 20 of the attaching / detaching means 5 in the same direction as the rotation unit 15 rotates in the direction of arrow B, but the outer pipe 2 is excavated. Since the engaging pin 18 is grounded on the soil, the engaging pin 18 does not need to raise the machine frame 1 to move the rotary unit 15 upward, so that even if the engaging pin 18 comes to the central three-way portion of the inverted T-shaped engaging groove 19, the vertical groove portion is formed. It does not move to the 19a side. Then, when the rotating unit 15 is further rotated in the same direction, the outer tube 2 rotates together with the rotating unit 15 from the time when the engaging pin 18 engages with the left end engaging portion 19c of the engaging groove 19. With the rotation of the outer tube 2, the engagement pin 22 of the attachment / detachment means 9 fixed to the lower end of the outer tube 2 moves, and the engagement pin 22 is L-shaped engaged as shown by the phantom line in FIG. When it reaches the left end corner portion 23c of the groove 23, raise the machine frame 1,
By pulling up the outer tube 2 via the rotation unit 15, the engagement pin 22 is caused to have a vertical groove portion 23 a of the engagement groove 23.
The short pipe 8 for mounting the excavating blade is separated from the outer pipe 2 as a result of escape through the engaging groove 23.

A pair of digging blades 7, 7 are fixed to the digging blade mounting short pipe 8 at diametrically opposed positions thereof by welding or the like, and each digging blade 7 has a blade portion 7a along its lower side. ,
As shown in FIG. 1, the blade portion 7a is arranged so that the outer end thereof protrudes outward from the outer peripheral surface of the outer tube 2 and the inner end of the blade portion 7a largely extends to the vicinity of the central portion of the inner tube 3. .

Next, a method of forming a cast-in-place concrete support pile by using the support pile forming apparatus having the above-described structure will be described. In this support pile construction work, first, on the ground, the rotary unit 15 below the machine frame 1
The outer pipe 2 and the inner pipe 3 are connected to each other via attachment / detachment means 4 and 5, and the excavating blade mounting short pipe 8 is connected to the lower end of the outer pipe 2 via attachment / detachment means 9. The connecting state of the rotary unit 15, the inner pipe 3, the outer pipe 2, and the excavating blade mounting short pipe 8 by the attaching / detaching means 4, 5, 9 is as shown by the solid line in FIG.

Then, the wire for raising and lowering operation is fed out to lower the whole apparatus, and the outer tube 2 and the inner tube 3 are rotated by the rotation driving means 6 through the rotation unit 15, so that the outer tube 2
While excavating the ground by the excavating blade 7 attached to the excavating blade attaching short pipe 8 at the lower end, both the inner and outer pipes 2 and 3 are driven into the ground. At the same time when the injection of both pipes 2 and 3 is started, air is supplied to each air ejection pipe 12, and jet air is ejected from the excavated soil discharge hole 11 of the outer pipe 2 to the outside of the outer pipe 2 through each nozzle 12a. At this time, the jet air is ejected from the excavated soil discharge hole 11 of the outer pipe 2 so that the space 10 for introducing the excavated soil is in a negative pressure state.

As described above, when the ground is excavated by the rotation of the excavating blade 7 attached to the short pipe 8 for attaching the excavating blade at the lower end of the outer pipe 2, the excavated soil is used for introducing the excavated soil in a negative pressure state. The excavated soil introduced into the space portion 10 is forcibly discharged from the excavated soil discharge hole 11 to the outside of the outer pipe 2 together with the jet air ejected from each nozzle 12a, and adheres to the wall surface side of the excavated hole. . In this case, since a large number of excavated soil discharge holes 11 are formed from the lower portion to the upper portion of the outer pipe 2, the excavated soil that cannot be discharged through the excavated soil discharge holes 11 on the lower side is sequentially excavated on the upper side. It is discharged from the soil discharge hole 11.

When the inner and outer pipes 2 and 3 are driven to a predetermined depth in the ground, the operation of the rotary drive device 6 is stopped and the rotation of the rotary unit 15 is temporarily stopped. Then, the rotation driving device 6 is reversely operated at a low speed to rotate the rotation unit 15 in a direction (arrow B direction in FIG. 3) opposite to the rotation direction (arrow B direction) at a required angle, for example, 30 to 40 degrees. After that, when the machine frame 1 is raised through the lifting wire, the attaching / detaching means 4 connecting the rotating unit 15 and the outer tube 2 maintains the connected state of both, but the rotating unit 15 Attaching / detaching means 5 connecting the inner pipe 3 with the outer pipe 2
The attaching / detaching means 9 that connects the short pipe 8 for mounting the excavating blade,
As shown in FIG. 4, only the outer pipe 2 is pulled up while being connected to the rotary unit 15, and the inner pipe 3 and the digging blade mounting short pipe 8 are released.
Will be separated from the rotary unit 15 and the outer tube 2 and will remain in the hole. In this case, the periphery of the inner pipe 3 left in the hole is, as shown in FIGS. 3 and 4,
The excavated soil discharged from the excavated soil discharging hole 11 of the outer pipe 2 is completely filled.

After pulling the outer tube 2 to the ground,
Reinforcing bars 24 are inserted into the inner pipe 3 left in the ground, cement mortar and ready-mixed concrete 25 are filled, and a reinforced concrete pile 26 integral with the inner pipe 3 is formed. At the lower part of the reinforced concrete pile 26, the excavating blade mounting short pipe 8 left with the inner pipe 3 is buried together with the excavating blade 7 in excavated soil.

In the embodiment described above, the inner and outer pipes 2 and 3 are driven to a predetermined depth in the ground, the inner pipe 3 is separated from the machine frame 1 and left in the ground, and then the rebar is inserted into the inner pipe 3. Although concrete is filled, concrete may be filled by inserting a reinforcing bar into the inner pipe 3 before driving the inner and outer pipes 2 and 3. Further, in the embodiment, the inner pipe 3
Although the rebar was inserted in the above, the rebar may be omitted and only concrete may be filled. Further, in the embodiment, the outer pipe and the inner pipe are both excavated while rotating, but the inner pipe may be fixed to the machine frame without being rotated and only the outer pipe may be rotated. .

Further, in the supporting pile forming apparatus of the present invention,
The attaching / detaching means for detachably connecting the lower portion of the machine frame and the outer pipe and the inner pipe, and the detaching means for detachably connecting the outer pipe and the short pipe for mounting the cutting blade are the attaching / detaching means of the above-described embodiment. The structure is not limited to 4, 5, 9 and various other structures can be used.

[0022]

According to the supporting pile construction method according to claim 1 of the present invention, at the time of driving both the inner and outer pipes, the blade portion of the excavating blade mounting short pipe connected to the lower end of the outer pipe is rotated. Due to the rotating action of the excavating blade whose inner end projects inside the inner pipe, the ground is excavated over almost the entire area of the cross section surrounded by the outer pipe, which significantly reduces the ground resistance on the lower end side of the inner pipe. As a result, the ground can be excavated efficiently at high speed, and thus the pipe driving work efficiency can be greatly improved. Moreover, since the inner pipe is closed at the lower end and is buried in the ground itself, groundwater and mud will not enter before and after driving, and the inner pipe is filled with concrete. This will reinforce the piles, and therefore very strong concrete piles can be constructed.

According to the method of claim 2, the excavated soil is forcibly introduced into the excavated soil introducing space into the excavated hole, and the excavated soil is discharged from the excavated soil discharge hole of the outer pipe together with the jet air to the outside of the outer pipe, Since it is attached to the inner wall surface of the hole, the soil can be discharged smoothly, the work of driving the pipe can be performed more efficiently, and the collapse of the wall surface of the hole at the time of the hole can be prevented.

Further, in the supporting pile forming apparatus of the present invention according to claim 3, the outer pipe and the inner pipe for burying are respectively attached to the lower portion of the machine frame suspended by the reader so as to be able to move up and down via attaching means. Detachably connected so as to be detachable, and at least the outer pipe is interlockingly connected to the rotation driving means provided in the machine frame, and at the lower end of this outer pipe, a short pipe for attaching an excavating blade having an excavating blade is attached via a detaching means. Since it is connected so that it can be separated, it is possible to accurately perform the connection and disconnection work between the machine frame and the outer pipe and the inner pipe, and the connection and disconnection operation between the outer pipe and the short pipe for mounting the cutting blade,
The support pile construction method of claim 1 described above can be efficiently implemented.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a support pile forming device according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along line XX of FIG.

FIG. 3 is an explanatory diagram showing a specific example of an attaching / detaching means.

FIG. 4 is an explanatory view showing a state in which the inner pipe and the short pipe for mounting the cutting blade are left in the ground and the outer pipe is pulled up.

FIG. 5 is an explanatory view showing a state where a reinforcing bar is inserted into an inner pipe left in the ground and concrete is filled.

[Explanation of symbols]

 1 Machine Frame 2 Outer Pipe 3 Inner Pipe 4 Attachment / Detachment Means 5 Attachment / Detachment Means 6 Rotation Driving Means 7 Excavation Blades 8 Excavation Blade Attachment Short Pipes 11 Excavation Soil Discharge Holes 12 Air Ejection Pipes 15 Rotation Units 18 Engagement Pins 19 Engagement Grooves 20 Engagement pin 21 Engagement groove 22 Engagement pin 23 Engagement groove

Claims (4)

[Claims] 1. An excavating blade in which an embedded inner pipe having a closed lower end is concentrically inserted into the outer pipe, and an inner end of a blade portion projects into the inner pipe at the lower end of the outer pipe. The excavating blade attaching short pipe to which is attached is detachably connected, and after both pipes are driven to a predetermined depth in the ground while rotating at least the outer pipe, the excavating blade attaching short pipe is attached. The pipe is separated from the outer pipe, and the short pipe for mounting the excavating blade and the inner pipe are left in the ground, the outer pipe is pulled up from the ground,
A method for constructing a support pile, comprising filling the inner pipe with concrete. 2. A plurality of excavated soil discharge holes are provided in the outer pipe, a space for introducing excavated soil is formed in a space between the outer pipe and the inner pipe, and jet air is supplied to the space. 2. An air jetting means for jetting out from the excavated soil discharge hole to the outside of the outer pipe is provided, and jet air is jetted from each of the excavated soil discharge holes by the air jetting means while driving the both pipes. Construction method for support piles described in. 3. An outer pipe and an embedded inner pipe, which is concentrically inserted into the outer pipe and has a closed lower end, are attached to and detached from a lower portion of a machine frame suspended by a leader so as to be vertically movable. A detachable connection is made via the means, and at least the outer tube of the inner and outer tubes is interlockingly connected to the rotation driving means provided in the machine frame, and the inner end of the blade portion is connected to the lower end of the outer tube. An apparatus for constructing a support pile, characterized in that a short pipe for attaching an excavating blade to which an excavating blade protruding to the inside of an inner pipe is attached is detachably connected via a detaching means. 4. The outer pipe is provided with a large number of excavated soil discharge holes, and a space portion for introducing excavated soil from a lower end thereof is provided in a space portion between the outer pipe and the inner pipe. The support pile forming apparatus according to claim 3, wherein the support pile is formed, and an air ejecting means for ejecting jet air from the excavated soil discharge hole to the outside of the outer pipe is provided in the space portion.