JP2003064680A - Method for removing existing pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for removing an existing pile, in which the existing pile is not crushed in a casing intruded into ground, in which the existing pile can be easily pulled out, which enables the safe and efficient removal of the existing pile, and which allows a posthole after the removal of the existing pile to be closely backfilled with sediment, so as to be capable of offering stable ground. SOLUTION: This method for removing the existing pile comprises: a process in which the double-structure casing, composed of outside and inside pipes which are relatively movable in an axial direction, is intruded into the ground around the existing pile, in which the inside pipe and the pile are pulled out together in such a manner that the outside pipe is left behind, and in which the outside pipe is pulled out; and a process for backfilling a space part of the posthole.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a construction method for removing an existing pile in the ground.

[0002]

2. Description of the Related Art In an existing building, a foundation pile may be installed in the ground below the building in order to safely support the load of the building on the ground. When rebuilding a building or redeveloping a land, the existing foundation piles (existing piles) installed in the ground beneath the old building are lacking in basic performance and low reliability, In many cases, it cannot be reused as a foundation pile for a new structure. At this time, if the existing piles are not removed but left in the ground, they interfere with the new piles, so the installation place of the new piles is limited. Due to this limitation, it may not be possible to install the new pile directly under the pillar of the new structure, which is the optimum place for supporting the load of the new structure, and it may be necessary to install the new pile at another place. In such a case, a problem arises in that the foundation beam of the new structure must be reinforced and then the load of the new structure must be supported by the new pile through the reinforced foundation beam. In order to solve such a problem, it is necessary to remove the existing piles so that the new piles can be installed at the optimum locations.

As a conventional method for removing existing piles,
A ring is drilled around the existing pile, the casing penetrates into the ground around the existing pile, the existing pile is taken into the casing, and the existing pile taken into the casing is crushed by a crusher etc. There is an all-casing construction method. Further, in Japanese Patent Laid-Open No. 10-252065, a casing is inserted into the ground around an existing pile to take the existing pile into the casing, and the upper portion of the existing pile is gripped by a gripping means to separate the existing pile and the ground. An invention of a method for recovering an existing structure in which an existing pile is lifted up by a crane after being separated and an existing pile in a portion protruding above the ground is cut by a cutting device and carried out is described.

Further, in Japanese Patent Laid-Open No. 10-292372, a casing is penetrated into the ground around an existing pile through a lubricant to take the existing pile into the casing, and the existing lubricant is added through the lubricant. The invention of a method for removing obstacles in which a pile is smoothly lifted by a crane and the existing pile is removed without crushing is described.

[0005]

In the conventional method of removing existing piles by the all-casing method, it is necessary to crush all the existing piles that do not need to be crushed when they are brought out to the ground, and in recent years, large-diameter cast-in-place casters have been used. There is a problem that it is very inefficient to remove existing piles such as piles, which is an inefficient work.

Further, in the invention described in Japanese Patent Application Laid-Open No. 10-252065, it is necessary to leave the casing and pull out the existing piles taken in the casing to the ground. However, since frictional force works between the inner wall of the casing, the sand and sand inside the casing, and the existing piles, work to separate the existing piles from the ground against these frictional forces and pull the existing piles to the ground while leaving the casings There was a problem that the work was difficult.

Further, in the invention described in Japanese Patent Laid-Open No. 10-292372, the existing pile is hoisted by a crane and pulled out once on the ground. However, even if the existing pile is large, the existing pile has a height corresponding to the length of the existing pile. Need to lift the stake.
Therefore, there is a problem that the work of removing the existing pile is dangerous. Also, with these methods of removing existing piles, it is necessary to refill the pile holes remaining after removing the existing piles with earth and sand,
There was a problem that the soil would not be solid just by putting it into the long pile hole from the surface and the ground would not be stable after the pile was removed.

The present invention has been made in order to eliminate the above-mentioned problems of the prior art, and the purpose thereof is to eliminate the need for crushing existing piles in a casing penetrating into the ground, and to eliminate existing problems. It is easy to pull out the pile from the ground, the existing pile can be removed safely and efficiently, and the pile hole after removing the existing pile can be backfilled to obtain stable ground. Is to provide a method.

[0009]

The present invention has the following constitution in order to solve the problems. According to the invention of claim 1, a casing having a double structure composed of an outer pipe and an inner pipe that are relatively movable in the axial direction is penetrated into the ground so as to surround an existing pile buried in the ground. However, the method is a method of removing an existing pile, in which the outer pipe is left, the earth and sand surrounded by the inner pipe and the existing pile are extracted together with the inner pipe, and then the outer pipe is extracted.

The casing has an excavation bit at its tip, which is rotated around an axis by a driving device to excavate the circumference of the existing pile in an annular shape corresponding to the length of the existing pile, and the outer pipe and the inner pipe are integrated. Penetrate into the ground. If the existing pile is long, extend the casing and excavate. As a result, the existing pile is taken inside the inner pipe. Since the inner pipe of the casing is axially movable relative to the outer pipe, the inner pipe can be pulled out toward the surface, leaving the outer pipe in the ground. Inside the inner pipe, the existing piles and the sediment around the existing piles are taken in, and a frictional force acts between the inner wall of the inner pipe and the sediment around the existing piles, and Friction also works between certain soil and existing piles. For this reason, when the inner pipe is pulled out, the existing pile and the soil around the existing pile are also pulled out toward the ground surface along with the inner pipe.

After withdrawing the inner tube, the outer tube remains. The outer tube is axially movable relative to the inner tube so that the remaining outer tube can then be withdrawn to the surface. In the invention of claim 2, the space portion formed after the earth and sand and the existing pile are extracted together with the inner pipe is backfilled by supplying a filler from between the outer pipe and the inner pipe. It is characterized by the method of removing existing piles.

[0012] When the inner pipe, the existing pile and the sediment around the existing pile are pulled out toward the surface of the ground by the process of pulling out the inner pipe, a space is formed thereafter at the position where the pile and the surrounding sediment existed. . Since there is a gap between the outer pipe and the inner pipe of the casing, a filler such as cement mixed earth and sand is fed back from the surface of the earth to the space through the gap.

The invention of claim 3 is characterized in that at least one existing pile is removed by repeating the steps from the extraction of the inner pipe, the earth and sand, and the existing pile to the extraction of the outer pipe. It is characterized by the method of removing existing piles. When the length of the existing pile is long, if the entire existing pile is pulled out to the ground by one step of pulling out the inner pipe and pulling out the outer pipe, the existing pile and the inner pipe will reach the height corresponding to the length of the existing pile. The outer pipe is pulled out to the ground, which makes ground work inefficient. For this reason, when removing long existing piles, perform the steps of pulling out the inner pipe and the outer pipe by a length that makes ground work efficient,
After that, the process of pulling out the inner pipe and the process of pulling out the outer pipe by a length that does not hinder the above-ground work are repeated until the entire existing pile is pulled out from the ground. It is also possible to incorporate two or more existing piles inside the inner tube depending on the inner diameter of the inner tube.

According to a fourth aspect of the present invention, the inner pipe, the earth and sand, and the existing pile are pulled out by applying a reaction force to the outer pipe. It is characterized by a removal method. The invention of claim 5 is
The removal method of the existing pile according to claim 3, wherein the extraction of the outer pipe is performed by applying a reaction force to the existing pile that has not been drawn yet.

According to this method, since the earth and sand put into the space will be compacted by the existing piles,
Eventually a solid clay pillar will be formed in the ground,
The effect of ground improvement can also be expected.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. 1 to 4 are explanatory views of respective work steps showing an embodiment of the present invention. The casing 20 used in this embodiment includes an outer pipe 21 and an inner pipe 2 which are straight pipes.
It is a double pipe consisting of 2 and an outer pipe 21 and an inner pipe 22.
Can be moved relative to each other in the axial direction.

A gap 23 is formed between the outer pipe 21 and the inner pipe 22. In order to secure this gap 23, a spacer (not shown) is provided on the inner wall surface of the outer pipe 21 and the inner pipe 2.
It is assumed that it is provided on at least one of the outer wall surfaces of No. 2 and the gap 23 is continuous from one end of the casing 20 to the other end. Both the outer tube 21 and the inner tube 22 can be formed by connecting a plurality of tubes,
Conventional means such as welding or screwing is used for the joining. Further, it goes without saying that the outer tube 21 and the inner tube 22 have dimensions and strength necessary for performing the operation described later.

An annular excavation bit 26 for excavating the ground 35 is provided at the tip portion of the outer pipe 21 of the casing 20 which is connected (see FIG. 5). The inner diameter of the tip of the drill bit 26 is the same as or close to the inner diameter of the inner pipe 22, and the tapered portion 2 is continuous with this portion.
5 at the upper end of which the drill bit 26 is connected to the outer pipe 21. The tip of the inner pipe 22 and the outer pipe 21
There is an opening 24 of a gap 23 between it and the inner wall of the.

The process of removing the existing piles 10 begins with a penetration process in which the casing 20 penetrates into the ground 35.
First, the casing 20 is erected on the ground directly above the existing piles 10 by a crane, and only the own weight of the casing 20 or a downward load is applied thereto, and the casing 20 is rotated around its axis by the drive device.
The excavation bit 26 at the tip of excavates the ground 35 around the existing pile 10 in an annular shape by a distance corresponding to the length of the existing pile 10, and accordingly, when the outer pipe 21 penetrates into the ground 35, The inner pipe 22 also penetrates into the ground 35 together. When a plurality of pipes are connected to form the outer pipe 21 and the inner pipe 22, the next pipe is connected to the upper end of the previously penetrated pipe on the ground, and then the above-mentioned penetration work is restarted. In this penetration step, since the inner diameter of the tip of the drill bit 26 and the inner diameter of the inner pipe 22 are the same or similar, the inner pipe 22 and the outer pipe 21 are smoothly penetrated.

Then, the excavation bit 26 excavates to a distance corresponding to the length of the existing pile 10, and the penetration process ends when the lower end of the casing 20 has penetrated to this point. Figure 1
[Fig. 6] is an explanatory diagram of a state in which the penetration step is completed. In the state where the penetration step is completed, the existing pile 10 is taken inside the inner pipe 22 together with the earth and sand 36 around the existing pile 10. After the penetration step, proceed to the inner tube drawing step. FIG. 2 is an explanatory diagram of the inner tube drawing process. Since the inner pipe 22 is movable in the axial direction relative to the outer pipe 21, the inner pipe 22 can be pulled out while leaving the outer pipe 21. Outer tube 21 and inner tube 22
There is a gap 23 secured by the spacer between them, the frictional force acting between the outer pipe 21 and the inner pipe 22 is small, and the inner pipe 22 can be easily pulled out. The inner tube 22 is pulled out by a jack or the like having the outer tube 21 supporting a reaction force.

The earth and sand 36 around the existing pile and the inner pipe 22
A frictional force works between the inner walls of the existing piles, and a frictional force also works between the earth and sand 36 around the existing piles and the existing piles 10. For this reason, when the inner pipe 22 is pulled out, the existing pile 10 together with the inner pipe 22 is pulled out.
And the earth and sand 36 around the existing piles are also pulled out. After the inner pipe 22, the earth and sand 36 therein and the existing pile 10 are pulled out toward the surface of the earth, the space portion 31 surrounded by the outer pipe 21 is formed. Atmosphere is introduced into the space 31 through the gap 23 of the casing 20 as the space 31 becomes larger. Since the outer pipe 21 is provided, the earth and sand do not collapse from the hole wall of the pile hole inside the space 31, and the space 31 does not gently fill due to the collapse of the hole wall.

The tip of the inner pipe 22 and the outer pipe 21
Although there is an opening 24 between the inner walls of the inner tube 22, as the inner tube 22 is pulled out, the position of the opening 24 moves toward the surface by the distance that the inner tube 22 is pulled out. The distance for pulling out the inner pipe 22 is determined by the conditions of the ground 35, the capacity of the jack or other on-site pulling equipment, and the efficiency of ground work. The inner pipe 22 is pulled out by a predetermined distance, and the inner pipe pulling process is once completed.

After the inner tube drawing step, a backfilling step is performed. Figure 3
[FIG. 7] is an explanatory diagram of a backfilling step. The ground and the space 31 communicate with each other through the gap 23 and the opening 24. Through the gap 23 and the opening 24, the earth and sand 32 can be sent from the ground into the space 31. At this time, the air in the space 31 passes through the gap 23 and a part of the opening 24, and the air in the space 31 is discharged from the casing 20.
Is discharged from above and the space 31 is backfilled with earth and sand 32, and the backfilling process is once completed. The earth and sand 32 is composed of cement-mixed earth and sand, and is adjusted so as to have fluidity that enables the space portion 31 to be backfilled from the bottom in a compact manner without gaps, and to have a curing time that allows backfilling to be performed efficiently. Also,
In the inner tube drawing step, the distance for drawing the inner tube 22 can be adjusted to adjust the space 31 to a volume that facilitates backfilling work.

Further, depending on the land use conditions after the removal of the existing piles 10, the earth and sand 32 may not be cement mixed earth and sand, but may be other kinds of improved earth or ordinary earth and sand. After the backfilling process, the process proceeds to the outer pipe drawing process. FIG. 4 is an explanatory diagram of the outer tube drawing process. Since the outer tube 21 is movable in the axial direction relative to the inner tube 22, only the outer tube 21 can be pulled out toward the surface. The outer pipe 2 is separated by a distance corresponding to the distance from which the inner pipe 22 is pulled out in the previous inner pipe drawing process.
It is good to pull out 1. At this time, the outer pipe 21 is pulled out by a jack or the like supporting a reaction force on the upper end of the existing pile 10 which is pulled out halfway. Since the filled earth and sand 32 are solidified under the existing pile 10, the existing pile 1
0 can sufficiently support the reaction force. Outer tube 2
After pulling out 1, the ground 35 that is densely backfilled with the earth and sand 32 is left. The outer tube 21 is pulled out by a predetermined distance, and the outer tube pulling-out process is once completed.

By the inner pipe drawing process and the outer pipe drawing process, the above-ground protruding portion 37 is formed on the ground surface. Therefore, after the outer pipe drawing step, the above-ground protruding portion 37 is removed.
Although this removal is performed by cutting, in addition to cutting the casing 20, in the case where the inner tube 22 and the outer tube 21 are connected to each other and a screwing means is used as the connecting means, the above-mentioned screwing is performed. You may go open. The outer pipe 21 and the inner pipe 22 that have been cut or removed, and the cut existing pile 10 and the earth and sand 36 around the existing pile are carried out from the work site, and a work space is secured at the installation location of the existing pile on the ground surface. To be done.

The existing pile 10, the outer pipe 21, and the inner pipe 22 still remain in the ground 35. Therefore, even after this, the above-described inner pipe drawing process, backfilling process, outer pipe drawing process, and removal of the above-ground protruding portion 37 are repeated until the entire casing 20 and existing pile 10 are drawn out from the ground 35. In the present embodiment, the inner tube drawing step, the backfilling step, the outer tube drawing step, and the removal of the above-ground protruding portion 37 are performed.
It was decided to repeat until the whole of the existing pile 10 was pulled out from the ground 35. However, depending on the length of the existing pile 10, the capacity of the work equipment used, the conditions of the work place, the conditions of the ground 35, etc. It is needless to say that the existing pile 10 can be removed by only performing the drawing process, the backfilling process, the outer pipe drawing process, and the removal of the above-ground protruding portion 37 once.

Further, in the present embodiment, the backfilling step is performed after the inner tube withdrawing step, but instead, the space section 31 can be backfilled with the earth and sand 32 while pulling out the inner tube. Further, in the outer tube drawing step, the space section 31 can be simultaneously backfilled with the earth and sand 32 while drawing the outer tube. Further, in the present embodiment, the jack in which the reaction force is supported on the upper end of the existing pile 10 is used in the outer pipe drawing step, but a jack in which the reaction force is supported on the ground surface may be used instead. .

Depending on the conditions of the ground 35 and working conditions, the outer pipe drawing process is not performed each time each backfilling process is completed, but instead, only the inner pipe drawing process and the backfilling process are repeated several times. The outer tube withdrawing step may be performed in the order of steps. In addition, in the present embodiment, the ground projecting portion 37 is removed every time the inner pipe drawing step is completed, but instead, the length of the ground projecting portion 37 becomes a length that enables efficient ground work. It is also possible to repeat the inner pipe drawing process, the backfilling process, and the outer pipe drawing process, and then remove the above-ground protruding portions 37 collectively.

Further, although the inner pipe drawing process and the outer pipe drawing process are repeated, it goes without saying that the drawing distance in each repeating process can be changed depending on the condition of the ground 35. Further, in the present embodiment, the number of existing piles taken into the inside of the inner pipe 22 is one, but it is also possible to take a plurality of existing piles into the inside of the inside pipe 22 and remove them at the same time.

[0030]

Since the present invention is a method for removing the existing pile as described above, it has the following effects. Since a casing having a double structure consisting of an outer pipe and an inner pipe that are relatively axially movable is inserted around the existing pile, the outer ground of the outer pipe and the inner ground of the inner pipe can be cut off. Therefore, it becomes easy to pull out the inner pipe to the ground surface together with the existing pile. Therefore, it is possible to cut and remove the existing pile in the portion pulled out to the ground surface, and it is not necessary to crush the existing pile in the casing penetrating into the ground, and the work can be performed safely and efficiently.

Further, the existing piles and casing portions having a length that can be handled by ground work are removed by projecting them on the ground surface. Therefore, even if the existing pile is long, it is not necessary to lift the existing pile to a height corresponding to the length of the existing pile, and the existing pile can be safely and efficiently removed. Furthermore, since the space part of the pile hole can be made to have a volume capable of performing the backfilling work properly and efficiently, the space part can be densely backfilled with the filler, and a stable ground can be obtained after the existing piles are removed. be able to.

That is, it is not necessary to crush the existing piles in the casing that penetrates into the ground, it is easy to pull out the existing piles from the ground, and the existing piles can be safely and efficiently removed. There is an effect that it is possible to provide a method for removing existing piles that can obtain stable ground by backfilling the pile holes after removing the existing piles.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a state in which a penetration step is completed in an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an inner pipe drawing step in the embodiment of the present invention.

FIG. 3 is an explanatory diagram of a backfilling step in the embodiment of the present invention.

FIG. 4 is an explanatory diagram of an outer tube drawing step in the embodiment of the present invention.

FIG. 5 is a partial vertical cross-sectional view of the tip of the casing.

[Explanation of symbols]

10 existing piles 20 casing 21 Outer tube 22 Inner tube 23 Gap 24 opening 25 Tapered part 26 drilling bits 31 Pile hole space 32 earth and sand 35 ground 36 Sediment around existing piles 37 Overhanging part on the ground

Claims (5)

[Claims] 1. A casing having a double structure consisting of an outer pipe and an inner pipe that are relatively axially movable is penetrated into the ground so as to surround an existing pile buried in the ground, A method for removing an existing pile, characterized in that, with the outer pipe left, the earth and sand surrounded by the inner pipe and the existing pile are pulled out together with the inner pipe, and then the outer pipe is pulled out. 2. The space portion formed after the earth and sand and the existing pile are pulled out together with the inner pipe is backfilled by supplying a filler from between the outer pipe and the inner pipe. The method for removing the existing pile described in 1. 3. The method according to claim 1, wherein at least one existing pile is removed by repeating extraction of the inner pipe, the earth and sand, and the existing pile to the extraction of the outer pipe. How to remove existing piles. 4. The existing pile according to claim 1, wherein the inner pipe, the earth and sand, and the existing pile are pulled out by applying a reaction force to the outer pipe. Removal method. 5. The method for removing an existing pile according to claim 3, wherein the extraction of the outer pipe is performed by applying a reaction force to the existing pile that has not been drawn yet.