How to remove existing piles

Abstract

To provide an unconventional and very practical pulling-out method of an existing pile.SOLUTION: A pulling-out method of an existing pile 60 is to repeat a lifting / cutting process such as lifting the existing pile 60 buried in a ground 50 and cutting an upper end part of the existing pile 60, comprising inserting and arranging, in an excavation hole 51 formed in the ground 50 surrounding the existing pile 60, a long connection member 1 for pulling-up provided with a connection part 1a for connection with the existing pile 60, and in the lifting / cutting process, backfilling material 40 is filled through the excavation hole 51 into a pulling-up space part 52 created between a lower end part of the existing pile 60 and the ground 50 by pulling-up the long connection member 1 for pulling-up connected on the existing pile 60.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for extracting an existing pile. [Background technology]

[0002] BACKGROUND ART Conventionally, a method for extracting an existing pile disclosed in Patent Document 1 (hereinafter referred to as the "conventional method") has been proposed as a method for extracting an existing pile buried in the ground.

[0003] In this conventional method, a casing with a diameter larger than the outer diameter of the existing pile is rotated and buried so as to surround the existing pile, to at least the depth of the existing pile. Next, a through hole is drilled along the central axis of the existing pile, and then a long hanging material 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 material is expanded and hooked onto the bottom end of the existing pile. Next, the long hanging material is pulled up from above to pull up the existing pile. After that, the hole (pulling space) surrounded by the casing created by pulling out the existing pile is filled with backfill material (soil and sand), and finally the casing is removed to complete the work. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4006841 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional methods require large-scale equipment (large heavy machinery such as cranes) to raise, lower, and rotate the casing, which has the problem that they cannot be applied to narrow construction sites surrounded by buildings, for example.

[0006] Furthermore, as mentioned above, in 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 is a concern that the backfill material may not be packed densely, or that the casing may be removed after the backfill material has been filled, resulting in a void in the area where the casing has been removed.

[0007] The present invention has been made in consideration of the above-mentioned problems, and provides a novel and highly practical method for extracting an existing pile. [Means for solving the problem]

[0008] The gist of the present invention will be explained with reference to the accompanying drawings.

[0009] This method for extracting an existing pile involves repeatedly lifting an existing pile 60 buried in the ground 50 and cutting the upper end of the existing pile 60, thereby extracting the existing pile 60. This method involves forming a plurality of boreholes 51 in the ground 50 around the existing pile 60, inserting a lifting long connecting member 1 having a connecting portion 1a that connects to the existing pile 60 into some of the boreholes 51, and in the lifting cutting step, lifting the lifting long connecting member 1 connected to the existing pile 60, thereby filling an extraction space 52 formed between the lower end of the existing pile 60 and the ground 50 with backfill material 40 through the boreholes 51 into which the lifting long connecting member 1 has not been inserted.

[0010] Also, there is provided a method for extracting an existing pile (60) by repeatedly performing an ascent and severance process of raising an existing pile (60) buried in the ground (50) and cutting the upper end portion of the existing pile (60), the method comprising the steps of: forming a borehole (51) in the ground (50) around the existing pile (60) for inserting and disposing a lifting long connecting member (1) having a connecting portion (1a) for connecting to the existing pile (60); inserting and disposing the lifting long connecting member (1) into the borehole (51); and then connecting the lifting long connecting member (1) to the existing pile (60) in the ground (50) around the existing pile (60). The method for extracting an existing pile is characterized in that by pulling up the pulled-up long connecting member 1, a borehole 51 is formed in 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, by pulling up the pulled-up long connecting member 1 connected to the existing pile 60, the backfill material 40 is filled in the extraction space 52 through the borehole 51 in which the pulled-up long connecting member 1 is not inserted.

[0011] Also, claims 1,2 This is a method for extracting an existing pile as described in any one of the above items, 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.

[0012] Also, claims 1,2 In any one of the methods for extracting existing piles, 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.

[0013] Also, claims 3 In the method for extracting existing piles described above, the excavation holes 51 into which the backfill material 40 is filled are each formed between the excavation holes 51 into which the pulled-up long connecting members 1 are inserted and arranged.

[0014] Also, claims 1,2In any one of the methods for extracting an existing pile described above, 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.

[0015] Also, claims 3 In the method for extracting an existing pile described above, 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.

[0016] Also, claims 4 In the method for extracting an existing pile described above, 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.

[0017] Also, claims 5 In the method for extracting an existing pile described above, 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.

[0018] Also, claims 1,2 This relates to a method for extracting an existing pile as described in any one of the claims, 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.

[0019] Also, claims 3In the method for extracting an existing pile described above, the backfill material 40 is filled into the extraction space 52, and then the existing pile 60 is lowered and the backfill material 40 is compacted by the pressure of the existing pile 60.

[0020] Also, claims 4 In the method for extracting an existing pile described above, the backfill material 40 is filled into the extraction space 52, and then the existing pile 60 is lowered and the backfill material 40 is compacted by the pressure of the existing pile 60.

[0021] Also, claims 5 In the method for extracting an existing pile described above, the backfill material 40 is filled into the extraction space 52, and then the existing pile 60 is lowered and the backfill material 40 is compacted by the pressure of the existing pile 60.

[0022] Also, claims 6 In the method for extracting an existing pile described above, the backfill material 40 is filled into the extraction space 52, and then the existing pile 60 is lowered and the backfill material 40 is compacted by the pressure of the existing pile 60.

[0023] Also, claims 7 In the method for extracting an existing pile described above, the backfill material 40 is filled into the extraction space 52, and then the existing pile 60 is lowered and the backfill material 40 is compacted by the pressure of the existing pile 60.

[0024] Also, claims 8 In the method for extracting an existing pile described above, the backfill material 40 is filled into the extraction space 52, and then the existing pile 60 is lowered and the backfill material 40 is compacted by the pressure of the existing pile 60.

[0025] Also, claims9 In the method for extracting an existing pile described above, the backfill material 40 is filled into the extraction space 52, and then the existing pile 60 is lowered and the backfill material 40 is compacted by the pressure of the existing pile 60. [Effects of the Invention]

[0026] Since the present invention has the above-mentioned configuration, it does not require large-scale facilities as in the conventional method described above, and can be applied even to narrow construction areas. Moreover, the backfilling work can be carried out smoothly without creating voids in the areas backfilled with backfill material, making it an unprecedented and extremely practical method for extracting existing piles. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 2 is a perspective view showing an existing pile extraction device used in this embodiment. [Figure 2] FIG. 2 is an exploded perspective view of the main parts of the existing pile extraction device used in this embodiment. [Figure 3] FIG. 1 is a process diagram of a method for extracting an existing pile according to this embodiment. [Figure 4] FIG. 1 is a process diagram of a method for extracting an existing pile according to this embodiment. [Figure 5] FIG. 1 is a process diagram of a method for extracting an existing pile according to this embodiment. [Figure 6] FIG. 1 is a process diagram of a method for extracting an existing pile according to this embodiment. [Figure 7] FIG. 1 is a process diagram of a method for extracting an existing pile according to this embodiment. [Figure 8] FIG. 1 is a process diagram of a method for extracting an existing pile according to this embodiment. [Figure 9] FIG. 1 is a process diagram of a method for extracting an existing pile according to this embodiment. [Figure 10] FIG. 1 is a process diagram of a method for extracting an existing pile according to this embodiment. [Figure 11] FIG. 1 is a process diagram of a method for extracting an existing pile according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0028] A preferred embodiment of the present invention will be briefly described below, illustrating the operation of the present invention with reference to the drawings.

[0029] A long-length connecting member 1 having a connecting portion 1a that connects to the existing pile 60 is inserted into an excavation hole 51 formed in the ground 50 around the existing pile 60, and then, in the upward cutting process, the long-length connecting member 1 connected to the existing pile 60 is pulled up, and the backfill material 40 is filled through the excavation hole 51 into the extraction space 52 formed between the lower end of the existing pile 60 and the ground 50.

[0030] Therefore, there is no need for large-scale equipment to raise, lower, or rotate the casing as in the conventional example, and the present invention can be reliably applied even in narrow construction locations.

[0031] 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 occur in the area backfilled with the backfilling material 40. [Example]

[0032] Specific embodiments of the present invention will be described with reference to the drawings.

[0033] This embodiment is a method for extracting an existing pile 60 by repeatedly performing an ascent and cutting process of raising an existing pile 60 buried in the ground 50 and cutting off the upper end portion of the existing pile 60, and an existing pile extraction device G is provided for use in this method for extracting the existing pile 60. The existing pile 60 (columnar improvement body) in this embodiment is, for example, a concrete ground reinforcement structure with a length of approximately 10 m and a diameter of approximately 60 cm that supports a building to be constructed on the ground 50.

[0034] 1 and 2, this existing pile extraction device G has a plurality (four) of long lifting connecting members 1 connected 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) according to this embodiment is constructed to a weight and size that can be carried manually by an operator.

[0035] The long-length lifting connecting member 1 is a rod-shaped body with a circular cross section made of an appropriate metal material as shown in Figures 1 and 2, has a predetermined length (longer than the existing pile 60), and has a screw groove 1b formed on its entire circumferential surface into which nut members 4a and 5a associated with the fastening bodies 4 and 5 described later are screwed.

[0036] In this embodiment, the long lifting connecting member 1 is made up of a single long rod-shaped member, but it may also be made up of a plurality of short rod-shaped members joined together.

[0037] This long lifting connecting member 1 is inserted into the through-hole portions 11b, 12b provided in each of the fixed plate 11 and the lifting plate 12 that constitute the lifting structure 10 described later, and in this state is prevented from coming out via the fastening members 4, 5 (nut members 4a, 5a and nut receiving members 4b, 5b), so that it is suspended and supported on each of the fixed plate 11 and the lifting plate 12.

[0038] That is, in this embodiment, a fastening member 4 is provided for supporting the lifting long connecting member 1 in a hanging manner on the fixed plate 11, and a fastening member 5 is provided for supporting the lifting long connecting member 1 in a hanging manner on the lifting plate 12.

[0039] These fastening bodies 4, 5 are formed from appropriate metal members as shown in Figures 1 and 2, and consist of nut members 4a, 5a that are screwed onto the lifting long connecting member 1, and nut receiving members 4b, 5b that are placed on the upper surfaces of each of the plates 11, 12 and support the nut members 4a, 5a.

[0040] The nut receiving members 4b, 5b are U-shaped bodies that fit over the lifting long connecting member 1 so that they can be slid through, and are configured to have a larger diameter than the through-hole portions 11b, 12b described later, thereby providing a support receiving function (washer function) for the nut members 4a, 5a.

[0041] Therefore, the fastening bodies 4, 5 (nut members 4a, 5a and nut receiving members 4b, 5b) can easily change the fastening position 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 the lifting plate 12.

[0042] Furthermore, the lower end of the lifting long connecting member 1 is provided with a connecting portion 1a that is engaged and connected to the lower end of the existing pile 60 (a portion buried in the ground).

[0043] This connecting portion 1a is formed from an appropriate metal member as shown in Figures 1 and 2, and consists of a base member 1a' attached to the lower end of the long-length lifting connecting member 1, and a thin rectangular plate-shaped locking member 1a" whose base end is pivotally attached to this base member 1a' so that it can be freely raised and lowered (opened and closed) from a lying state (vertically attached state) to an upright state (horizontal state) relative to the long-length lifting connecting member 1 (base member 1a').

[0044] 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.

[0045] The locking member 1a'' is constantly biased in the rising direction by a biasing member (not shown).

[0046] 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 upper surface, and a lifting plate 12 that is arranged above the fixed plate 11 at a distance and moves up and down by the operation of the jacks 13, and the fixed plate 11 and the lifting plate 12 are plates of the same structure as described below.

[0047] 1 and 2, the fixed plate 11 and the lifting plate 12 are circular plate-like bodies made of appropriate metal members, and have existing pile passage holes 11a and 12a in the center to allow the passage of the extracted existing pile 60. In the method for extracting the existing pile 60 according to this embodiment, the existing pile 60 is not passed through the existing pile passage hole 12a of the lifting plate 12, but the fixed plate 11 and the lifting plate 12 have the same structure for the sake of manufacturing efficiency and work efficiency.

[0048] The existing pile-passing hole portions 11a, 12a are circular, and eight through-hole portions 11b, 12b are provided at equal intervals (45-degree intervals) on the inner edge of the hole at radial positions.

[0049] The through-hole portions 11a, 12a have a diameter that allows the aforementioned long-length connecting member 1 to be slidably inserted therethrough, and are provided in an open state in the existing pile-passing hole portions 11a, 12a.

[0050] The lifting structure 10 according to this embodiment also has a support 14 that is installed on the upper surface of the ground 50 and on which the fixed plate 11 is placed.

[0051] This support body 14 is a frame-shaped body formed by arranging support members 14a made of appropriate metal members (H-beams) in a square shape when viewed from the top, as shown in Figures 1 and 2, and its upper surface is set as a support surface on which the fixed plate 11 is placed.

[0052] 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 is freely retractable from this cylinder portion 13a, and has the capacity to lift the existing pile 60.

[0053] 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).

[0054] Therefore, by operating the jack 13 (moving the operating rod 13b in and out), the lifting plate 12 can be raised and lowered.

[0055] In addition, this embodiment is provided with a drilling pipe 3 (steel pipe: SGP100A) for forming the drilling hole 51 (pull-up drilling hole 51a) and a drilling pipe 7 (plastic pipe: VP100A) for forming the drilling hole 51 (backfill drilling hole 51b), and both are supplied with drilling liquid W1 (water) via a hose 6 from a drilling liquid supply source not shown.

[0056] In addition, in this embodiment, a filler discharge pipe 2 is provided which is inserted into the excavation hole 51 (backfilling excavation hole 51b) and used to fill the filler 40 into the extraction space 52 formed between the lower end of the existing pile 60 and the ground 50.

[0057] Filler 40 (sand) is supplied to this filler discharge pipe 2 from a filler supply source (not shown) via a pressure-fed liquid W (water).

[0058] A method for extracting the existing pile 60 using the existing pile extraction device G configured as described above will now be described.

[0059] The method for extracting an existing pile 60 in this embodiment involves pre-extraction work such as forming boreholes 51 (boreholes 51a for lifting and boreholes 51b for backfilling) in the ground 50 surrounding the existing pile 60, inserting and arranging a long-length connecting member 1 for lifting and a filler discharge pipe 2 into the boreholes 51, and installing an existing pile extraction device G above the existing pile 60, and extraction work which involves repeatedly performing an ascent and cutting process to raise the existing pile 60 and cut the upper end of the existing pile 60.

[0060] First, the pre-pulling operation will be described.

[0061] While pressing the drilling pipe 3 (steel pipe: SGP100A) against the ground 50, drilling liquid W1 (water) is sprayed from a hose 6 arranged inside the drilling pipe 3 to excavate downward, forming a drilling hole 51 (pulling drilling hole 51a) of about 10 cm 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.

[0062] Next, when the long lifting connecting member 1 associated with 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 end opening of the excavation pipe 3, the locking member 1a" rises slightly. In this state, the excavation pipe 3 is left in place and only the long connecting member 1 is pulled up slightly, and the edge of the lower end opening of the excavation pipe 3 is used to bring the locking member 1a" into a fully raised state (a state in which it can be locked and connected to the lower end of the existing pile 60). After that, the excavation pipe 3 is pulled out and removed, and the long lifting connecting member 1 is inserted and arranged in the lifting borehole 51a (see (a) to (d) in Figure 4).

[0063] In the manner described above, four boreholes 51 (boreholes 51a for lifting) are formed in the ground 50 around the existing pile 60 at equal intervals around the circumference, into which the long connecting members 1 are inserted (see (e) in Figure 4).

[0064] Next, a drilling pipe 7 (plastic pipe: VP100A) is pressed against the ground 50 around the existing pile 60 between each pair of lifting drilling holes 51a into which the long lifting connecting members 1 have been inserted, and drilling liquid W1 (water) is sprayed from a hose 6 disposed inside the drilling pipe 7 to excavate downward, forming drilling holes 51 (backfilling drilling holes 51b) of approximately 10 cm in diameter until the lower end of the drilling pipe 7 reaches a position below the lower end of the existing pile 60, after which the drilling pipe 7 is pulled out and removed (see (a) to (d) in Figure 5). The drilling pipe 7 is configured by joining and connecting multiple short tubular bodies.

[0065] In the same manner as above, four boreholes 51 (backfilling boreholes 51b) into which the long connecting members 1 are not inserted are formed at equal circumferential intervals in the ground 50 around the existing pile 60 (see (e) in Figure 5). In this embodiment, the filler filling pipe 2 is inserted into the drilling pipe 7 that forms the last backfilling borehole 51b before it is pulled out, thereby disposing the filler filling pipe 2 in the backfilling borehole 51b. Note that the filler filling pipes 2 may be inserted into multiple backfilling boreholes 51b to fill the filler 40 from multiple locations, or the filler 40 may be filled from the drilling pipe 7 without using the filler filling pipe 2 or in combination with the filler filling pipe 2.

[0066] Next, the lifting structure 10 for the existing pile extraction device G is installed.

[0067] Specifically, a fixed plate 11 is placed on a support 14 arranged on the top surface of the ground 50 around the existing pile 60, and a lifting plate 12 is placed on top of a jack 13 (with the operating rod 13b in a recessed position) placed on the top surface of this fixed plate 11.At this time, a lifting long connecting member 1 inserted into a borehole 51 (lifting borehole 51a) is inserted into the through-hole portions 11b, 12b of the fixed plate 11 and the lifting plate 12, and a fastening member 5 (nut member 5a and nut receiving member 5b) is attached to this lifting long connecting member 1 to prevent it from coming loose, thereby supporting the lifting long connecting member 1 in a hanging position on the lifting plate 12 (see Figure 6).

[0068] In this embodiment, the excavation hole 51 (pulling excavation hole 51a) into which the lifting long connecting member 1 is inserted and the excavation hole 51 (backfilling excavation hole 51b) into which the lifting long connecting member 1 is not inserted are both formed in positions near the existing pile 60, and are provided at positions (near the existing pile 60) where they function as friction reduction holes (edge ​​separation holes) that reduce friction with the ground 50 that occurs when the existing pile 60 is lifted, but only one of them, for example, only the backfilling excavation hole 51b, may function as a friction reduction hole. Alternatively, eight excavation holes 51 may be formed at equal intervals in the circumferential direction in the ground 50 around the existing pile 60, and then the lifting long connecting member 1 may be inserted and disposed in only some of the excavation holes 51.

[0069] Next, the extraction operation will be described.

[0070] When the jack 13 in the lifting structure 10 is raised (the operating rod 13b is thrust) to raise the lifting plate 12 by 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 by 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).

[0071] Next, the fastening member 4 (nut member 4a and nut receiving member 4b) 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 fixed plate 11.In this state, the fastening member 5 (nut member 5a and nut receiving member 5b) is removed from the lifting long connecting member 1, the lifting plate 12 is removed, and the upper end portion of the existing pile 60 that protrudes above the fixed plate 11 is removed (cut) (see Figure 8).

[0072] Next, filler 40 (sand) is extracted via pumped liquid W from a 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 another backfilling borehole 51b (see Figure 9). In this embodiment, the timing for filling the filler 40 into the extraction space 52 is after the existing pile 60 has been raised a predetermined amount (after the upper end portion of the existing pile 60 has been removed), but the filler 40 may also be filled at the same time as the existing pile 60 is being raised until it is raised a predetermined amount.Furthermore, the excavation hole 51 into which the filler 40 is filled is not limited to the backfilling excavation hole 51b, but the filler 40 may be filled into the extraction space 52 through the lifting excavation hole 51a.Furthermore, the excavation hole 51 from which the pumped liquid W is discharged is not limited to the backfilling excavation hole 51b, but the pumped liquid W may be discharged to the ground through the lifting excavation hole 51a.

[0073] Next, the lifting plate 12 is placed on top of the jack 13 (with the operating rod 13b in a protruding state), and at this time, the lifting long connecting member 1 is inserted into the through-hole portion 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 off, and the lifting long connecting member 1 is suspended and supported on 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 depressed), and the existing piles 60 are lowered, and the backfill material 40 (sand) is compacted by the pressure (weight) of the existing piles 60 (see FIG. 10). 11), and when the jack 13 is further lowered (the operating rod 13ba is retracted), the existing pile 60 does not descend as it is supported by the backfill material 40 and only the lifting plate 12 descends, and when the lowering operation of the jack 13 stops, the descent of the lifting plate 11 also stops, and this lifting plate 11 is pulled up via the fastening body 5 to support the long connecting member 1 in a hanging manner, and in this state when the jack 13 is raised (the operating rod 13b is thrust), the existing pile 60 rises a predetermined amount and passes through the existing pile passage hole portion 11b of the fixed plate 11, with the upper end of the existing pile 60 protruding above the fixed plate 11 (see FIG. 11), and the upper end of the existing pile 60 protruding above the fixed plate 11 is cut off.

[0074] Thereafter, the lifting and cutting process is repeated in the same manner as above to pull out the entire existing pile 60 from the ground 50.

[0075] 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 the conventional example; only small-scale equipment capable of drilling holes in the ground 50 is required, and the present invention can be reliably applied even in narrow construction locations.

[0076] Furthermore, in this embodiment, the backfill material 40 is filled into the extraction space 52 through the backfilling excavation hole 51b, so that by raising the existing pile 60, the backfill material 40 can be reliably filled into the extraction space 52 formed between the lower end of the existing pile 60 and the ground 50, and no cavities will be created in the area backfilled with the backfill material 40.

[0077] In this embodiment, a borehole 51 (borehole for lifting 51a) is formed in the ground 50 around the existing pile 60, into which the long lifting connecting member 1 having the connecting portion 1a for connecting to the existing pile 60 is inserted and disposed, and the long lifting connecting member 1 is inserted and disposed in the borehole 51 (borehole for lifting 51a). After that, 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 in the extraction space 52 formed between the existing pile 60 and the existing pile 60, and the backfilling material 40 is filled into the extraction space 52 through the borehole 51 (backfilling borehole 51b) in which the extraction long connecting member 1 is not inserted, by pulling up the long connecting member 1 connected to the existing pile 60 in the lifting cutting process, so that the existing pile 60 is lifted and the backfilling material 40 is filled in smoothly.

[0078] 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 from one borehole 51 (backfilling borehole 51b) together with the pumped liquid W, and the pumped liquid W is discharged to the ground from another borehole 51 (backfilling borehole 51b), so that the filling of the backfilling material 40 is carried out smoothly.

[0079] In addition, in this embodiment, the boreholes 51 (pulling borehole 51a and backfilling borehole 51b) function as friction reduction holes that reduce friction with the ground 50 that occurs when the existing pile 60 is raised, so that the existing pile 60 can be raised smoothly.

[0080] In addition, in this embodiment, the filler discharge pipe 2 for discharging the filler 40 is inserted into the excavation hole 51 (backfilling excavation hole 51b) and the filler 40 is extracted and filled into the space portion 52, so that the filling of the filler 40 is also carried out smoothly in this respect.

[0081] Furthermore, in this embodiment, after filling the extraction space 52 with the 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 that in this respect too, no cavities are created in the areas backfilled with the backfill material 40.

[0082] The present invention is not limited to this embodiment, and the specific configuration of each component can be designed as appropriate. [Explanation of symbols]

[0083] W Pumped liquid 1. Lifting long connecting member 1a Connecting part 40 Backfill material 50 Ground 51 Borehole 52 Pull-out space 60 Existing piles

Claims

1. A method for extracting an existing pile by repeatedly performing an upward cutting process to raise an existing pile buried in the ground and cut off the upper end of the existing pile, the method comprising the steps of: forming a plurality of boreholes in the ground around the existing pile; inserting long lifting connecting members having connecting portions that connect to the existing pile into some of the boreholes; and filling the extraction space formed between the lower end of the existing pile and the ground by raising the long lifting connecting members connected to the existing pile in the upward cutting process with backfill material through the boreholes into which the long lifting connecting members have not been inserted.

2. This method for extracting an existing pile involves repeatedly performing an upward cutting process to raise an existing pile buried in the ground and cut off the upper end of the existing pile, thereby extracting the existing pile. The method comprises the steps of: forming a borehole in the ground around the existing pile into which a lifting long connecting member having a connecting portion that connects to the existing pile is inserted; inserting and disposing the lifting long connecting member into the borehole; then lifting the lifting long connecting member connected to the existing pile into the ground around the existing pile to form a borehole into which backfill material is filled in an extraction space formed between the lower end of the existing pile and the ground; and in the upward cutting process, lifting the lifting long connecting member connected to the existing pile to fill the extraction space with backfill material via a borehole into which the lifting long connecting member was not inserted.

3. 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.

4. 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.

5. 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.

6. 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.

7. 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.

8. 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.

9. 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.

10. 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.

11. 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.

12. 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.

13. 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.

14. 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.

15. 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.

16. 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.

17. 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.

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