JP7778668B2 - How to remove existing piles - Google Patents

Description

The present invention relates to a method for extracting existing piles.

Conventionally, a method for extracting existing piles buried in the ground has been proposed, such as the method disclosed in Patent Document 1 (hereinafter referred to as the "conventional method").

In this conventional method, a casing with a larger diameter than the outer diameter of the existing pile is rotated and buried around the existing pile, to at least the same depth as the existing pile. A through-hole is then drilled along the central axis of the existing pile, after which a long hanging member is inserted into the through-hole from above until its lower tip is slightly deeper than the bottom of the hole. The lower tip of the long hanging member is expanded and hooked onto the bottom end of the existing pile. The long hanging member is then pulled up from above to pull up the existing pile. The hole (extraction space) surrounded by the casing created when the existing pile is then filled with backfill material (soil and sand), and the casing is finally removed to complete the work.

Patent No. 4006841

However, conventional methods require large-scale equipment (large heavy machinery such as cranes) to raise, lower, and rotate the casing, which poses the problem of not being applicable to narrow construction sites surrounded by buildings, for example.

In addition, as mentioned above, with the conventional method, the hole left by the extraction of the existing pile is filled with backfill material after the entire pile has been pulled out. However, there are cases where this backfill material is not packed tightly, and because the casing is removed after the backfill material has been filled, there is a concern that a void may form in the area where the casing was removed.

The present invention was made in consideration of the above-mentioned problems, and provides a highly practical method for extracting existing piles that has not previously existed.

The gist of the present invention will be explained with reference to the attached drawings.

This method for extracting an existing pile (60) buried in the ground (50) involves repeatedly lifting the pile (60) and cutting the upper end of the pile (60) to extract the pile. This method involves forming multiple boreholes (51) in the ground (50) surrounding the existing pile (60), inserting long lifting connecting members (1) with connecting portions (1a) that connect to the existing pile (60) into some of the boreholes (51), and, during the lifting and cutting process, lifting the long lifting connecting members (1) connected to the existing pile (60) to form extraction spaces (52) between the lower end of the existing pile (60) and the ground (50) with backfill material (40) through the boreholes (51) into which the long lifting connecting members (1) are not inserted.

In addition, there is a method for extracting an existing pile (60) by repeatedly performing an ascent and severance process in which an existing pile (60) buried in the ground (50) is raised and the upper end of the existing pile (60) is cut off. The method involves forming a borehole (51) in the ground (50) surrounding the existing pile (60) into which a long, lifting connecting member (1) having a connecting portion (1a) for connecting to the existing pile (60) is inserted, inserting the long, lifting connecting member (1) into the borehole (51), and then connecting the long, lifting connecting member (1) to the existing pile (60) in the ground (50) surrounding the existing pile (60). This method involves pulling up the long-length connecting member 1, forming a borehole 51 into which backfill material 40 is filled in the extraction space 52 formed between the lower end of the existing pile 60 and the ground 50, and in the upward cutting process, pulling up the long-length connecting member 1 connected to the existing pile 60, filling the extraction space 52 with backfill material 40 through the borehole 51 into which the long-length connecting member 1 is not inserted.

Furthermore, the present invention relates to a method for extracting an existing pile as described in any one of claims 1 and 2 , characterized in that the backfill material 40 is filled into the extraction space 52 from one of the boreholes 51 together with the pressurized liquid W, and the pressurized liquid W is discharged to the ground from the other of the boreholes 51.

Furthermore, in the method for extracting existing piles described in either claim 1 or 2, the method for extracting existing piles is characterized in that the excavation holes 51 into which the backfill material 40 is filled are formed between the excavation holes 51 into which the pulled-up long connecting members 1 are inserted and arranged.

In addition, the method for extracting existing piles described in claim 3 relates to a method for extracting existing piles, characterized in that the excavation holes 51 into which the backfill material 40 is filled are formed between the excavation holes 51 into which the pulled-up long connecting members 1 are inserted and arranged.

In addition, in the method for extracting an existing pile described in either claim 1 or 2, the method for extracting an existing pile is characterized in that the excavation hole 51 into which the lifting long connecting member 1 is not inserted functions as a friction reduction hole that reduces friction with the ground 50 that occurs when the existing pile 60 is raised.

In addition, in the method for extracting an existing pile described in claim 3 , the excavation hole 51 into which the lifting long connecting member 1 is not inserted functions as a friction reduction hole that reduces friction with the ground 50 that occurs when the existing pile 60 is raised.

In addition, in the method for extracting an existing pile described in claim 4 , the excavation hole 51 into which the lifting long connecting member 1 is not inserted functions as a friction reduction hole that reduces friction with the ground 50 that occurs when the existing pile 60 is raised.

In addition, in the method for extracting an existing pile described in claim 5 , the excavation hole 51 into which the lifting long connecting member 1 is not inserted functions as a friction reduction hole that reduces friction with the ground 50 that occurs when the existing pile 60 is raised.

Furthermore, the present invention relates to a method for extracting an existing pile as described in either claim 1 or 2, characterized in that after filling the extraction space 52 with the backfill material 40, the existing pile 60 is lowered and the backfill material 40 is compacted by the pressure of the existing pile 60.

In addition, the method for extracting an existing pile described in claim 3 relates to a method for extracting an existing pile, characterized in that after filling the extraction space 52 with the backfill material 40, the existing pile 60 is lowered and the backfill material 40 is compacted by pressing the existing pile 60.

Furthermore, in the method for extracting an existing pile described in claim 4 , the method for extracting an existing pile is characterized in that after filling the extraction space 52 with the backfill material 40, the existing pile 60 is lowered and the backfill material 40 is compacted by the pressure of the existing pile 60.

Furthermore, the method for extracting an existing pile described in claim 5 relates to a method for extracting an existing pile, characterized in that after filling the extraction space 52 with the backfill material 40, the existing pile 60 is lowered and the backfill material 40 is compacted by the pressure of the existing pile 60.

In addition, the method for extracting an existing pile described in claim 6 relates to a method for extracting an existing pile, characterized in that after filling the extraction space 52 with the backfill material 40, the existing pile 60 is lowered and the backfill material 40 is compacted by the pressure of the existing pile 60.

Furthermore, the method for extracting an existing pile described in claim 7 relates to a method for extracting an existing pile, characterized in that after filling the extraction space 52 with the backfill material 40, the existing pile 60 is lowered and the backfill material 40 is compacted by the pressure of the existing pile 60.

Furthermore, the method for extracting an existing pile described in claim 8 relates to a method for extracting an existing pile, characterized in that after filling the extraction space 52 with the backfill material 40, the existing pile 60 is lowered and the backfill material 40 is compacted by the pressure of the existing pile 60.

Furthermore, the present invention relates to a method for extracting an existing pile as described in claim 9 , which is characterized in that after filling the extraction space 52 with the backfill material 40, the existing pile 60 is lowered and the backfill material 40 is compacted by the pressure of the existing pile 60.

As configured as described above, the present invention does not require the large-scale facilities required by the conventional methods described above, and can be applied to narrow construction areas. Furthermore, backfilling work can be carried out smoothly without creating voids in the areas backfilled with backfill material, making this an unprecedented and highly practical method for extracting existing piles.

FIG. 2 is a perspective view showing an existing pile extraction device used in this embodiment. FIG. 2 is an exploded perspective view of the main parts of the existing pile extraction device used in this embodiment. FIG. 1 is a process diagram of a method for extracting an existing pile according to this embodiment. FIG. 1 is a process diagram of a method for extracting an existing pile according to this embodiment. FIG. 1 is a process diagram of a method for extracting an existing pile according to this embodiment. FIG. 1 is a process diagram of a method for extracting an existing pile according to this embodiment. FIG. 1 is a process diagram of a method for extracting an existing pile according to this embodiment. FIG. 1 is a process diagram of a method for extracting an existing pile according to this embodiment. FIG. 1 is a process diagram of a method for extracting an existing pile according to this embodiment. FIG. 1 is a process diagram of a method for extracting an existing pile according to this embodiment. FIG. 1 is a process diagram of a method for extracting an existing pile according to this embodiment.

The preferred embodiment of the present invention will be briefly explained below, illustrating its operation with reference to the drawings.

A long, lifting connecting member 1 with a connecting portion 1a that connects to the existing pile 60 is inserted into a borehole 51 formed in the ground 50 around the existing pile 60. Then, in the upward cutting process, the long, lifting connecting member 1 connected to the existing pile 60 is pulled up, and the extraction space 52 formed between the lower end of the existing pile 60 and the ground 50 is filled with backfill material 40 through the borehole 51.

Therefore, there is no need for large-scale equipment to raise, lower, or rotate the casing as in conventional cases, and it can be reliably applied even in narrow construction locations.

In addition, in the present invention, the backfilling material 40 is filled into the extraction space 52 through the excavation hole 51, so the backfilling material 40 can be reliably filled into the extraction space 52, and no cavities will form in the area backfilled with the backfilling material 40.

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

This embodiment is a method for extracting an existing pile 60 buried in the ground 50 by repeatedly performing an ascent-and-cut process that raises the existing pile 60 and cuts off the top end of the existing pile 60. An existing pile extraction device G is provided for use in this method of extracting an existing pile 60. The existing pile 60 (columnar improvement body) in this embodiment is, for example, a concrete ground reinforcement structure approximately 10 m long and 60 cm in diameter that supports a building constructed on the ground 50.

As shown in Figures 1 and 2, this existing pile extraction device G has multiple (four) long lifting connecting members 1 that connect to existing piles 60, and a lifting structure 10 that lifts these long lifting connecting members 1. The existing pile extraction device G (long lifting connecting members 1 and lifting structure 10) in this embodiment is constructed to a weight and size that can be carried manually by an operator.

As shown in Figures 1 and 2, the long lifting connecting member 1 is a rod-shaped body with a circular cross section made from an appropriate metal member, has a predetermined length (longer than the existing pile 60), and has a threaded groove 1b formed on its entire periphery into which the nut members 4a, 5a of the fastening members 4, 5, described below, are threaded.

In this embodiment, the lifting long connecting member 1 is constructed from a single long rod-shaped member, but it may also be constructed by joining and connecting multiple short rod-shaped members.

This long lifting connecting member 1 is inserted into the through-holes 11b, 12b provided in the fixed plate 11 and the lifting plate 12 that make up the lifting structure 10 (described below), and is suspended from the fixed plate 11 and the lifting plate 12 by being prevented from coming loose by the fastening members 4, 5 (nut members 4a, 5a and nut receiving members 4b, 5b).

That is, in this embodiment, a fastener 4 is provided for supporting the lifting long connecting member 1 in a suspended manner on the fixed plate 11, and a fastener 5 is provided for supporting the lifting long connecting member 1 in a suspended manner on the lifting plate 12.

These fastening bodies 4, 5 are made of suitable metal members as shown in Figures 1 and 2, and consist of nut members 4a, 5a that screw onto the lifting long connecting member 1, and nut receiving members 4b, 5b that are placed on the upper surfaces of the plates 11, 12 and support the nut members 4a, 5a.

These nut receiving members 4b, 5b are U-shaped bodies that fit over the long lifting connecting member 1 so that they can be slid through. They are larger in diameter than the through-holes 11b, 12b (described below) and are configured to function as a support (washer) for the nut members 4a, 5a.

Therefore, the fastening bodies 4, 5 (nut members 4a, 5a and nut receiving members 4b, 5b) can easily change their fastening positions relative to the lifting long connecting member 1, and thus can easily change the hanging support position of the lifting long connecting member 1 relative to the fixed plate 11 and lifting plate 12.

In addition, the lower end of the lifting long connecting member 1 is provided with a connecting portion 1a that engages and connects to the lower end (ground-buried portion) of the existing pile 60.

As shown in Figures 1 and 2, this connecting portion 1a is made of an appropriate metal material and consists of a base member 1a' attached to the lower end of the long lifting connecting member 1 and a narrow, rectangular plate-shaped locking member 1a", the base end of which is pivotally attached to the base member 1a'. The locking member 1a" is able to rise and fall (open and close freely) from a lying position (vertically attached position) to an upright position (horizontal position) relative to the long lifting connecting member 1 (base member 1a').

Therefore, when the locking member 1a" is raised, it protrudes in a direction intersecting with the long connecting member 1, and in this protruding state it can be locked and connected to the lower end of the existing pile 60.

The locking member 1a" is constantly biased in the rising direction by a biasing member (not shown).

As shown in Figures 1 and 2, the lifting structure 10 has a fixed plate 11 that supports multiple (four) jacks 13 at equally spaced positions around the periphery of its top surface, and a lifting plate 12 that is spaced above the fixed plate 11 and moves up and down by the operation of the jacks 13. The fixed plate 11 and lifting plate 12 are plates of the same structure, as described below.

Specifically, as shown in Figures 1 and 2, the fixed plate 11 and lifting plate 12 are circular plate-shaped bodies made of suitable metal members, with existing pile passage holes 11a and 12a provided in the center to allow the passage of the extracted existing pile 60. Note that in the method for extracting an existing pile 60 according to this embodiment, the existing pile 60 is not passed through the existing pile passage hole 12a in the lifting plate 12, but for reasons of manufacturing and work efficiency, the fixed plate 11 and lifting plate 12 have the same structure.

The existing pile passage holes 11a, 12a are circular, with eight through-holes 11b, 12b provided at equal intervals (45-degree intervals) radially around the inner edge of the hole.

These through-holes 11a, 12a have a diameter that allows the aforementioned long-length lifting connecting member 1 to slide through, and are provided in an open state in the existing pile passage holes 11a, 12a.

The lifting structure 10 in this embodiment also has a support 14 that is installed on the top surface of the ground 50 and on which the fixed plate 11 is placed.

As shown in Figures 1 and 2, this support body 14 is a frame-shaped body formed by arranging support members 14a made of suitable metal members (H-beams) side by side in a square shape when viewed from above, and its upper surface is set as a support surface on which the fixed plate 11 is placed.

As shown in Figures 1 and 2, the jack 13 is a hydraulic jack consisting of a cylinder portion 13a and an operating rod 13b that can be freely extended and retracted from this cylinder portion 13a, and has the capacity to lift the existing pile 60.

In this embodiment, four jacks 13 are provided, and these four jacks 13 are configured to operate in conjunction with each other by being driven by a drive unit (not shown).

Therefore, the lifting plate 12 can be raised and lowered by operating the jack 13 (extending and retracting the operating rod 13b).

In addition, this embodiment is provided with a drilling pipe 3 (steel pipe: SGP100A) for forming the drilling hole 51 (pulling drilling hole 51a) and a drilling pipe 7 (plastic pipe: VP100A) for forming the drilling hole 51 (backfilling drilling hole 51b), both of which are supplied with drilling liquid W1 (water) via a hose 6 from a drilling liquid supply source (not shown).

In addition, in this embodiment, a filler discharge pipe 2 is provided, which is inserted into the borehole 51 (backfill borehole 51b) and used to fill the filler material 40 into the extraction space 52 formed between the lower end of the existing pile 60 and the ground 50.

Filler material 40 (sand) is supplied to this filler discharge pipe 2 via pressurized liquid W (water) from a filler supply source (not shown).

We will now explain how to extract an existing pile 60 using the existing pile extraction device G configured as described above.

The method for extracting an existing pile 60 in this embodiment involves pre-extraction work, such as forming boreholes 51 (pulling borehole 51a and backfill borehole 51b) in the ground 50 surrounding the existing pile 60, inserting and disposing a lifting long connecting member 1 and a filler discharge pipe 2 into these boreholes 51, and installing an existing pile extraction device G above the existing pile 60; and extraction work, which involves repeatedly raising the existing pile 60 and cutting the upper end of the existing pile 60 through an ascent and severing process.

First, let's explain the pre-removal work.

While pressing the drilling pipe 3 (steel pipe: SGP100A) against the ground 50, drilling liquid W1 (water) is sprayed from the hose 6 placed inside the drilling pipe 3, causing the drilling to proceed downward, forming a drilling hole 51 (pulling drilling hole 51a) approximately 10 cm deep until the lower end of the drilling pipe 3 reaches a position below the lower end of the existing pile 60 (see (a) to (c) in Figure 3). The drilling pipe 3 is made up of multiple short tubular bodies joined together.

Next, the long lifting connecting member 1 of the existing pile extraction device G is inserted into the excavation pipe 3 placed in the ground 50, and the connecting portion 1a is extracted from the lower opening of the excavation pipe 3, causing the locking member 1a" to rise slightly. In this state, the excavation pipe 3 is left in place, and only the long connecting member 1 is slightly pulled up, using the edge of the lower opening of the excavation pipe 3 to fully raise the locking member 1a" (so that it can be locked and connected to the lower end of the existing pile 60). The excavation pipe 3 is then pulled out and removed, leaving the long lifting connecting member 1 inserted and positioned in the lifting borehole 51a (see (a) to (d) in Figure 4).

In the manner described above, four boreholes 51 (boreholes for lifting 51a) are formed in the ground 50 around the existing pile 60 at equal intervals around the circumference, into which the long lifting connecting members 1 are inserted (see (e) in Figure 4).

Next, a drilling pipe 7 (plastic pipe: VP100A) is pressed against the ground 50 surrounding the existing pile 60 between each pair of lifting drill holes 51a into which the long lifting connecting members 1 have been inserted, while drilling liquid W1 (water) is sprayed from a hose 6 disposed within the drilling pipe 7 to excavate downward, forming a drilling hole 51 (backfill drilling hole 51b) approximately 10 cm deep until the lower end of the drilling pipe 7 reaches a position below the lower end of the existing pile 60. The drilling pipe 7 is then pulled out and removed (see (a) to (d) in Figure 5). The drilling pipe 7 is constructed by joining and connecting multiple short tubular bodies.

In the above manner, four equally spaced locations in the circumferential direction of the ground 50 around the existing pile 60 are used to form excavation holes 51 (backfilling excavation holes 51b) into which the long connecting members 1 are not inserted (see (e) in Figure 5). In this embodiment, the filler filling pipe 2 is inserted into the excavation pipe 7 that forms the last backfilling excavation hole 51b before it is pulled out, thereby placing the filler filling pipe 2 in the backfilling excavation hole 51b. It is also possible to insert and place filler filling pipes 2 in multiple backfilling excavation holes 51b and fill the filler 40 from multiple locations, or to fill the filler 40 from the excavation pipe 7 without using the filler filling pipe 2 or in combination with the filler filling pipe 2.

Next, the lifting structure 10 for the existing pile extraction device G is installed.

Specifically, a fixed plate 11 is placed on a support 14 placed on the top surface of the ground 50 surrounding the existing pile 60, and a lifting plate 12 is placed on top of a jack 13 (with the operating rod 13b retracted) placed on the top surface of the fixed plate 11. At this time, the lifting long connecting member 1 inserted into the borehole 51 (lifting borehole 51a) is inserted into the through-holes 11b, 12b of the fixed plate 11 and lifting plate 12. A fastener 5 (nut member 5a and nut receiver 5b) is attached to the lifting long connecting member 1 to prevent it from coming loose, so that the lifting long connecting member 1 is suspended and supported on the lifting plate 12 (see Figure 6).

In this embodiment, the excavation holes 51 (lifting excavation holes 51a) into which the lifting long connecting members 1 are inserted and the excavation holes 51 (backfilling excavation holes 51b) into which the lifting long connecting members 1 are not inserted are both formed in positions near the existing pile 60, and are provided in positions (near the existing pile 60) that function as friction-reducing holes (edge-cutting holes) that reduce friction with the ground 50 that occurs when the existing pile 60 is raised. However, only one of the holes, for example, only the backfilling excavation hole 51b, may function as a friction-reducing hole. Alternatively, eight excavation holes 51 may be formed at equal intervals circumferentially in the ground 50 around the existing pile 60, and then the lifting long connecting members 1 may be inserted into only some of the excavation holes 51.

Next, we will explain the extraction process.

When the jack 13 in the lifting structure 10 is raised (the operating rod 13b is thrust) to raise the lifting plate 12 a predetermined amount, the existing pile 60, to which the locking member 1a" of the lifting long connecting member 1 is locked and connected, is raised a predetermined amount. At this time, a pull-out space 52 is formed between the lower end of the existing pile 60 and the ground 50 (see Figure 7).

Next, the fasteners 4 (nut members 4a and nut receivers 4b) are attached to the lifting long connecting member 1 to prevent it from coming loose, so that the lifting long connecting member 1 is suspended and supported by the fixed plate 11. In this state, the fasteners 5 (nut members 5a and nut receivers 5b) are removed from the lifting long connecting member 1, the lifting plate 12 is removed, and the upper end of the existing pile 60 that protrudes above the fixed plate 11 is removed (cut off) (see Figure 8).

Next, filler material 40 (sand) is extracted via pumped liquid W from the filler filling pipe 2 inserted into one backfilling borehole 51b up to near the lower end of the existing pile 60, filling the space 52, and excess pumped liquid W that is not absorbed by the ground 50 is discharged to the ground via the other backfilling borehole 51b (see Figure 9). In this embodiment, the filler material 40 is filled into the extraction space 52 after the existing pile 60 has been raised a predetermined amount (after the upper end of the existing pile 60 has been removed). However, the filler material 40 may be filled simultaneously with the existing pile 60 while it is being raised until it is raised a predetermined amount. Furthermore, the borehole 51 into which the filler material 40 is filled is not limited to the backfill borehole 51b, and the filler material 40 may be filled into the extraction space 52 via the lifting borehole 51a. Furthermore, the borehole 51 from which the pumped liquid W is discharged is not limited to the backfill borehole 51b, and the pumped liquid W may be discharged to the ground via the lifting borehole 51a.

Next, the lifting plate 12 is placed on top of the jack 13 (with the operating rod 13b in the extended position). At this time, the lifting long connecting member 1 is inserted through the through-hole 12b of the lifting plate 12. The fasteners 5 (nut members 5a and nut receiving members 5b) are attached to the lifting long connecting member 1 to prevent it from coming loose, so that the lifting long connecting member 1 is suspended from the lifting plate 12. In this state, the suspension support of the lifting long connecting member 1 via the fasteners 4 to the fixed plate 11 is released, and the jack 13 is lowered (the operating rod 13b is retracted). This causes the existing pile 60 to descend, and the backfill material 40 (sand) is compacted by the pressure (weight) of the existing pile 60 (see Figure 10). See Figure 11), and when the jack 13 is further lowered (the operating rod 13ba is retracted), the existing pile 60 is supported by the backfill material 40 and does not descend, so only the lifting plate 12 descends. When the jack 13 stops lowering, the lifting plate 11 also stops descending, and the lifting plate 11 is pulled up via the fasteners 5 to support the long connecting member 1 in a suspended state. In this state, when the jack 13 is raised (the operating rod 13b is thrust), the existing pile 60 rises a predetermined amount, passes through the existing pile passage hole 11b of the fixed plate 11, and the upper end of the existing pile 60 protrudes above the fixed plate 11 (see Figure 11), and the upper end of the existing pile 60 protruding above the fixed plate 11 is cut off.

Then, repeat the upward cutting process as described above to pull out the entire existing pile 60 from the ground 50.

Since this embodiment is configured as described above, there is no need for large-scale equipment to raise, lower, or rotate the casing, as in conventional examples. Instead, only small-scale equipment large enough to drill holes in the ground 50 is required, making it possible to reliably apply the system even in narrow construction locations.

In addition, in this embodiment, the backfill material 40 is filled into the extraction space 52 via the backfilling borehole 51b. Therefore, by raising the existing pile 60, the extraction space 52 formed between the lower end of the existing pile 60 and the ground 50 can be reliably filled with the backfill material 40, and no cavities will form in the area backfilled with the backfill material 40.

In this embodiment, a borehole 51 (borehole for lifting 51a) is formed in the ground 50 around the existing pile 60, into which a long lifting connecting member 1 having a connecting portion 1a for connecting to the existing pile 60 is inserted, and the long lifting connecting member 1 is inserted and disposed in this borehole 51 (borehole for lifting 51a). Then, the long lifting connecting member 1 connected to the existing pile 60 is pulled up into the ground 50 around the existing pile 60, thereby connecting the lower end of the existing pile 60 to the ground 50. A borehole 51 (backfilling borehole 51b) is formed to fill the extraction space 52 formed between the existing pile 60 and the existing pile 60 with backfill material 40, and in the lifting and cutting process, the lifting long connecting member 1 connected to the existing pile 60 is pulled up, filling the extraction space 52 with backfill material 40 through the borehole 51 (backfilling borehole 51b) into which the lifting long connecting member 1 is not inserted. This allows the existing pile 60 to be lifted and the backfill material 40 to be filled in smoothly.

In addition, in this embodiment, multiple boreholes 51 (backfilling boreholes 51b) are formed in the ground 50 surrounding the existing pile 60, and the backfilling material 40 is filled into the extraction space 52 together with the pumped liquid W from one borehole 51 (backfilling borehole 51b), and the pumped liquid W is discharged to the ground from another borehole 51 (backfilling borehole 51b), so the filling of the backfilling material 40 is carried out smoothly.

In addition, in this embodiment, the boreholes 51 (pulling borehole 51a and backfilling borehole 51b) function as friction-reducing holes that reduce friction with the ground 50 that occurs when the existing pile 60 is raised, allowing the existing pile 60 to be raised smoothly.

In addition, in this embodiment, the filler discharge pipe 2, which discharges the filler 40, is inserted into the borehole 51 (backfilling borehole 51b), and the filler 40 is extracted and filled into the space 52, so in this respect too, the filling of the filler 40 is carried out smoothly.

In addition, in this embodiment, after filling the extraction space 52 with backfill material 40, the existing piles 60 are lowered and the backfill material 40 is compacted by the pressure of the existing piles 60, so in this respect too, no cavities are created in the area backfilled with backfill material 40.

Note that the present invention is not limited to this example, and the specific configuration of each component can be designed as appropriate.

W: pumped liquid 1: lifting long connecting member 1a: connecting portion
40 Backfill material
50 Ground
51 Borehole
52 Pull-out space
60 Existing piles

Claims (17)

An existing pile extraction method involves repeatedly lifting an existing pile buried in the ground and cutting off the upper end of the existing pile, thereby extracting the existing pile. This method involves drilling multiple boreholes in the ground surrounding the existing pile, inserting long, lifting connecting members with connecting portions that connect to the existing pile into some of the boreholes, and, in the lifting and cutting process, lifting the long, lifting connecting members connected to the existing pile, thereby filling the extraction space formed between the lower end of the existing pile and the ground with backfill material through the boreholes into which the long, lifting connecting members were not inserted. This method for extracting an existing pile involves repeatedly lifting an existing pile buried in the ground and cutting off the upper end of the pile. The method involves forming a borehole in the ground surrounding the existing pile into which a lifting long connecting member having a connecting portion that connects to the existing pile is inserted, inserting the lifting long connecting member into the borehole, and then lifting the lifting long connecting member connected to the existing pile into the ground surrounding the existing pile to form a borehole into which backfill material is filled in the extraction space formed between the lower end of the existing pile and the ground. During the lifting cutting process, the lifting long connecting member connected to the existing pile is lifted, thereby filling the extraction space with backfill material through a borehole into which the lifting long connecting member was not inserted. 3. A method for extracting an existing pile according to claim 1 , wherein the backfill material is filled into the extraction space from one of the boreholes together with pressurized liquid, and the pressurized liquid is discharged to the ground from the other of the boreholes. 3. The method for extracting an existing pile according to claim 1 , wherein the excavation holes into which the backfill material is filled are formed between the excavation holes into which the lifted long connecting members are inserted and arranged. 4. The method for extracting an existing pile according to claim 3 , wherein the excavation holes into which the backfill material is filled are formed between the excavation holes into which the lifted long connecting members are inserted and arranged. 3. A method for extracting an existing pile as described in claim 1 , wherein the excavation hole into which the lifting long connecting member is not inserted functions as a friction reduction hole that reduces friction with the ground that occurs when the existing pile is raised. 4. The method for extracting an existing pile according to claim 3 , wherein the excavation hole into which the lifting long connecting member is not inserted functions as a friction reduction hole that reduces friction with the ground that occurs when the existing pile is raised. 5. The method for extracting an existing pile according to claim 4 , wherein the excavation hole into which the lifting long connecting member is not inserted functions as a friction reduction hole that reduces friction with the ground that occurs when the existing pile is raised. 6. The method for extracting an existing pile according to claim 5 , wherein the excavation hole into which the lifting long connecting member is not inserted functions as a friction reduction hole that reduces friction with the ground that occurs when the existing pile is raised. 3. The method for extracting an existing pile according to claim 1 , wherein after filling the extraction space with the backfill material, the existing pile is lowered and the backfill material is compacted by pressing the existing pile. 4. The method for extracting an existing pile according to claim 3 , wherein after filling the extraction space with the backfill material, the existing pile is lowered and the backfill material is compacted by pressing the existing pile. 5. The method for extracting an existing pile according to claim 4 , wherein after filling the extraction space with the backfill material, the existing pile is lowered and the backfill material is compacted by pressing the existing pile. 6. The method for extracting an existing pile according to claim 5 , wherein after filling the extraction space with the backfill material, the existing pile is lowered and the backfill material is compacted by pressing the existing pile. 7. The method for extracting an existing pile according to claim 6 , wherein after filling the extraction space with the backfill material, the existing pile is lowered and the backfill material is compacted by pressing the existing pile. 8. The method for extracting an existing pile according to claim 7 , wherein after filling the extraction space with the backfill material, the existing pile is lowered and the backfill material is compacted by pressing the existing pile. 9. The method for extracting an existing pile according to claim 8 , wherein after filling the extraction space with the backfill material, the existing pile is lowered and the backfill material is compacted by pressing the existing pile. 10. The method for extracting an existing pile according to claim 9 , wherein after filling the extraction space with the backfill material, the existing pile is lowered and the backfill material is compacted by pressing the existing pile.