Pile extraction jig

Abstract

To easily remove an existing pile housed in a casing from the inside of the casing and reuse the pile.SOLUTION: A pile extraction jig 10 comprises a cylindrical casing 11, a connector 14 attached to a top plate 15 of the casing 11, and a plurality of excavation blades 16 arranged along the periphery of an opening of the casing 11. The casing 11 has a plurality of segments 11A, 11B divided along the axial direction of the casing 11. The plurality of segments 11A, 11B are composed of a fixed segment fixed to the top plate 15 and a pivoting segment 11B connected to the fixed segment 11A by a hinge mechanism 18 at an edge formed along the axial direction of the fixed segment 11A so that the interior 11S of the casing 11 can be freely opened and closed.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a pile extraction jig for extracting existing piles driven into the ground. [Background technology]

[0002] The Japan Construction Federation has issued "Guidelines for the Treatment of Existing Underground Structures." As a result, existing piles cannot be left in place due to the wishes of the client or due to budget or construction time constraints, and the importance of removing the piles has increased.

[0003] As a result, one such technique that has been proposed is a pile extraction jig that extracts existing piles driven into the ground (see, for example, Patent Document 1). This pile extraction jig is connected to an extraction machine such as a pile driver, and excavates the ground around the existing pile by rotating it with the power of the extraction machine and pushing it into the ground. When extracting the existing pile, the pile extraction jig is pulled up to the ground with the existing pile housed inside the casing, thereby extracting the existing pile from the ground. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-183501 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, since the existing piles are extracted while still housed within the casing of the pile extraction jig, it is not easy to remove the existing piles from within the casing, and it can be difficult to reuse the pile extraction jig.

[0006] The present invention has been made in consideration of such problems, and its object is to provide a pile extraction tool that can easily remove existing piles housed within a casing from within the casing and reuse them. [Means for solving the problem]

[0007] In view of the above problems, the pile extraction tool of the present invention is a pile extraction tool that is connected to an extraction machine and is rotated by the power of the extraction machine while being pushed into the ground, thereby excavating the ground around an existing pile and then extracting the existing pile. The pile extraction tool comprises a cylindrical casing that rotates about the axis of the existing pile as a rotation axis, has a top plate fixed to its upper end and has an opening at its lower end through which the existing pile is inserted, a connector that is attached to the top plate and connected to the extraction machine, and a plurality of excavation blades that are arranged along the periphery of the opening at the lower end of the casing, the casing having a plurality of segments divided along the axial direction of the casing, and the plurality of segments are composed of a fixed segment fixed to the top plate and a pivoting segment that is connected to the fixed segment by a hinge mechanism at an edge formed along the axial direction of the fixed segment so that the inside of the casing can be opened and closed freely.

[0008] According to the present invention, by connecting the connector to the extraction machine, the pile extraction jig can be attached to the extraction machine. In this state, the excavation blade arranged on the casing is directed downward, the axis of the existing pile is aligned with the rotation axis, and the excavation blade is pushed into the ground while rotating the casing around the rotation axis, and the excavation blade excavates the ground around the existing pile. As a result, the head of the existing pile is inserted from the opening of the casing, and as the excavation proceeds, the existing pile can be accommodated in the casing. After this state is reached, the existing pile accommodated in the casing is extracted together with the casing. Here, in the present invention, since a plurality of excavation blades are arranged along the periphery of the opening of the casing, the minimum amount of ground around the existing pile can be excavated, and therefore, when the existing pile is extracted together with the casing, the loosening and collapse of the ground can be suppressed.

[0009] Furthermore, the existing pile housed in the casing that has been pulled out of the ground can be easily opened in the axial direction by pivoting the pivot segment relative to the fixed segment using the hinge mechanism. This allows the pulled-out existing pile to be easily removed from inside the casing. After the existing pile has been removed from the casing, the pivot segment can be pivoted relative to the fixed segment using the hinge mechanism in the opposite direction to the above-mentioned direction to close the inside of the casing and form a cylindrical casing. This allows the pile extraction jig to be reused.

[0010] In a more preferred embodiment, the pivot segment is composed of a plurality of circumferential division bodies divided along the circumferential direction of the casing, and each of the circumferential division bodies is connected to the edge of the fixed segment by the hinge mechanism.

[0011] According to this embodiment, since the circumferential divided bodies are arranged above and below the casing, each circumferential divided body can be pivoted independently with respect to the fixed segment inside the casing, and the casing can be opened in a so-called one-way opening manner. This allows the inside of the casing to be opened without any hindrance even if locally compressed soil and sand are filled around the existing pile.

[0012] In another preferred embodiment, the pivot segment is composed of two axially divided bodies divided along the axial direction of the casing, and each of the axially divided bodies is connected by the hinge mechanism at each edge of the fixed segment.

[0013] According to this embodiment, the two axially divided bodies are arranged in the circumferential direction of the casing, and therefore, each axially divided body can be pivoted independently with respect to the fixed segment inside the casing, and the casing can be opened in a so-called double-opening manner. This allows the inside of the casing to be opened without any problems even if locally compressed soil and sand are filled around the existing pile.

[0014] In a more preferred embodiment, when the casing is viewed from the axial direction, the hinge mechanism is disposed inside a circumscribing circle where the plurality of excavation blades are in contact. According to this embodiment, since the hinge mechanism is disposed inside a circumscribing circle where the plurality of excavation blades are in contact, damage to the hinge mechanism during excavation can be suppressed.

[0015] In a more preferred embodiment, at least one of the fixed segment and the pivoting segment is formed with at least one long hole extending along the axial direction so as to communicate with the inside of the casing. According to this embodiment, the existing pile can be easily removed from the casing by pushing it out from the outside through the long hole.

[0016] In a more preferred embodiment, the cutting edge of the digging blade is positioned closer to the rotating shaft than the casing in a cross section passing through the rotating shaft, and the cutting edge is formed by a first surface inclined outwardly with respect to the axial direction and a second surface extending into the casing along the axial direction.

[0017] According to this embodiment, the cutting edge of the excavation blade is disposed closer to the rotation axis than the casing, and in this state, a first surface is formed from the cutting edge that is inclined outward in the axial direction, so that it is possible to prevent the crushed soil from excessively entering the inside of the casing during excavation. This makes it possible to prevent the crushed soil from entering in a compressed state between the casing and the existing piles housed in the casing, so that the pivot segment can be easily pivoted and the casing can be easily opened.

[0018] In a more preferred embodiment, the connecting body is provided with a pair of pins formed on a line perpendicular to the rotation axis, and a pair of retaining members into which each of the pair of pins is inserted and into which retaining holes are formed to hold the connecting body are fixed to the top plate, and the retaining holes are formed to a size such that, when the pair of pins are inserted, the casing can be freely tilted relative to the connecting body and can be freely moved in the axial direction.

[0019] According to this aspect, during excavation, the rotational torque, which is the power of the extractor, is transmitted to the pair of holding members from the pair of pins provided on the connecting body, and the casing rotates around the rotation axis. Furthermore, the pushing force, which is the power of the extractor, acts on the upper end of the casing through the pair of pins. When the casing is extracted, the pair of pins abut against the upper end of the holding hole as the casing moves upward, and the casing can be pulled up through the holding member. With the pair of pins in the arrangement state, the excavation blade located at the lower end of the casing is abutted against the ground, and the holding member is lowered together with the connecting body while rotating around each pin. This allows the casing suspended along the vertical direction to be tilted relative to the ground while avoiding interference with the extractor. As a result, the operator can easily open the casing by pivoting the pivot segment. Effect of the Invention

[0020] According to the present invention, an existing pile housed in a casing can be easily removed from the casing and reused. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a schematic perspective view of a pile extraction jig according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view showing the pile extraction jig shown in FIG. 1 in an open state. [Diagram 3]2A is a cross-sectional view of the pile extraction jig shown in FIG. 1 viewed downward from the center, and FIG. 2B is a cross-sectional view taken along line BB in FIG. [Figure 4] 13(a) to 13(e) are diagrams for explaining the operation of extracting an existing pile using a pile extraction jig. [Diagram 5] FIG. 11 is a schematic perspective view of a pile extraction jig according to a second embodiment of the present invention. [Figure 6] FIG. 13 is a schematic perspective view of a pile extraction jig according to a third embodiment of the present invention. [Figure 7] FIG. 13 is a schematic perspective view of a pile extraction jig according to a fourth embodiment of the present invention. [Figure 8] 13(a) to 13(d) are diagrams showing the positional relationship between the connector and the retaining member from the pile pulling-out operation to the operation of removing the existing pile. [Figure 9] FIG. 9 is a schematic perspective view illustrating the state shown in FIG. 8(d) with the casing open. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, some pile extraction jigs according to the present embodiment will be described with reference to Figs. 1 to 9.

[0023] [First embodiment] 1. About the pile extraction jig 10 The pile extraction jig 10 will be described below with reference to Figs. 1 to 3. Fig. 1 is a schematic perspective view of the pile extraction jig according to the first embodiment of the present invention. Fig. 2 is a perspective view showing the pile extraction jig shown in Fig. 1 in an open state. Fig. 3(a) is a cross-sectional view of the pile extraction jig shown in Fig. 1, viewed downward from the center, and Fig. 3(b) is a cross-sectional view taken along line BB in Fig. 3(a).

[0024] The pile extraction jig 10 according to this embodiment, as shown in Fig. 4 etc. described later, is connected to an extraction machine 30 such as a pile driver, and is rotated by the power of the extraction machine 30 while being pushed into the ground G, thereby excavating the ground G around the existing pile 3. After excavation, the existing pile 3 is housed inside the pile extraction jig 10, and the existing pile 3 is extracted together with the pile extraction jig 10.

[0025] The existing pile 3 is not limited to any particular type, such as a wooden pile, a small-diameter steel pipe pile, a precast concrete pile, or a cement pile (columnar improvement body), and its size is not limited as long as it has a diameter and length that can be accommodated within the casing 11 of the pile extraction jig 10 described below.

[0026] As shown in Figures 1 and 2, the pile extraction jig 10 includes a casing 11. The casing 11 is a cylindrical member that rotates about the axis of the existing pile 3 shown in Figure 4 as a rotation axis CL. A top plate 15 is fixed to the upper end of the casing 11, and an opening into which the existing pile 3 is inserted is formed at the lower end of the casing 11.

[0027] A connector 14, which is connected to the extractor 30, is attached to the top plate 15. Specifically, the connector 14 is a hexagonal columnar member extending along the rotation axis CL, and is fixed to the top plate 15 via a disk-shaped base 21. A plurality of (for example, three) reinforcing ribs 22 are provided at intervals in the circumferential direction of the rotation axis CL on the base 21 and the top plate 15. A plurality of excavation blades 16 are arranged at intervals in the circumferential direction along the periphery 11a of the opening of the casing 11 at the lower end of the casing 11.

[0028] In this embodiment, the casing 11 has a plurality of (e.g., two) segments divided along the axial direction of the casing. In this embodiment, the segments are composed of a fixed segment 11A and a pivot segment 11B, and the casing 11 has a so-called split structure. Note that in this embodiment, one fixed segment 11A and one pivot segment 11B are provided, but for example, a plurality of (e.g., two of each) fixed segments 11A and pivot segments 11B may be provided alternately in the circumferential direction, or a plurality of divided bodies (segments) obtained by dividing the pivot segment 11B may be provided, as described later.

[0029] In this embodiment, the fixed segment 11A is fixed at its upper end to the top plate 15. The fixed segment 11A has three long holes 13 extending along the axial direction so as to communicate with the interior 11S of the casing 11. In this embodiment, the pivot segment 11B is connected to the fixed segment 11A by a hinge mechanism 18 at an edge portion 11f formed along the axial direction of the fixed segment 11A so that the interior 11S of the casing 11 can be opened and closed. In this embodiment, the hinge mechanism 18 is a hinge, and connects the fixed segment 11A and the pivot segment 11B by a plurality of (e.g., five) hinges spaced apart along the axial direction.

[0030] 1, the fixed segment 11A and the pivot segment 11B are fixed to each other along the edge 11e along the axial direction by a plurality of (for example, five) fixing portions 17. The fixing portion 17 is composed of a fixing plate 17A and two fastening bolts 17B. The fixing plate 17A is fixed to the pivot segment 11B.

[0031] As shown in Fig. 2, when the pivot segment 11B is pivoted by the hinge mechanism 18 to bring the edge 11e of the pivot segment 11B into contact with the edge 11d of the fixed segment 11A, the inside 11S of the casing 11 is closed (see Fig. 1). In this state, a part of the fixed plate 17A overlaps with the outer peripheral surface of the fixed segment 11A, and the pivot segment 11B can be fixed to the fixed segment 11A by screwing a fastening bolt into the female thread formed on the fixed segment 11A. In this embodiment, the pivot segment 11B is fixed to the fixed segment 11A by the fastening bolt 17B, but, for example, a fixing pin may be used instead of the fastening bolt 17B, and, for example, a cable tie that goes around the fixed segment 11A and the pivot segment 11B may be used as the fixing part.

[0032] In this embodiment, a discharge pipe 19 is attached to the outer circumferential surface of the fixed segment 11A along the axial direction. The discharge pipe 19 extends downward to the vicinity of the excavation blade 16, and during excavation, a fluid such as water is caused to flow from above and discharged toward the excavation blade 16. This can improve the excavation performance of the excavation blade 16.

[0033] As shown in Fig. 3(a), when the casing 11 is viewed from the axial direction, the fixed part 17, the hinge mechanism 18, and the discharge pipe 19 are disposed inside the circumscribing circle c where the multiple excavation blades 16 are in contact. That is, the fixed part 17, the hinge mechanism 18, and the discharge pipe 19 are present inside the circumscribing circle c of radius R1 shown in Fig. 3(a). As a result, the fixed part 17, the hinge mechanism 18, and the discharge pipe 19 come into contact with the excavated soft ground during excavation, so that it is possible to prevent these members from being worn or damaged during excavation.

[0034] As shown in FIG. 3(a), the excavation blade 16 has a groove or the like on its upper surface, and is fixed, for example, by welding in a state of being engaged with the periphery 11a of the opening of the casing 11. The cutting edge 16a of the excavation blade 16 is disposed closer to the rotation axis CL than the casing 11 in a cross section passing through the rotation axis CL. Specifically, as shown in FIG. 3(b), the cutting edge 16a is formed by a first surface 16b inclined outward with respect to the axial direction, and a second surface 16c extending along the axial direction into the casing 11. That is, in this embodiment, as shown in FIG. 3(a), a part of the first surface 16b and the second surface 16c are disposed inside a circle formed by a radius R2 of the inner diameter of the casing 11 when viewed from a direction along the rotation axis CL.

[0035] In this way, the cutting edge 16a of the excavation blade 16 is disposed closer to the rotation axis CL than the casing 11, and in this state, a first surface 16b is formed from the cutting edge 16a, which is inclined outward in the axial direction. Therefore, during excavation in the extraction work described below, it is possible to prevent the crushed soil C from excessively entering the interior 11S of the casing 11. This makes it possible to prevent the crushed soil C from entering in a compressed state between the casing 11 and the existing pile 3 housed in the casing 11, so that the pivot segment 11B can be easily pivoted and the casing 11 can be easily opened.

[0036] 2. Regarding the removal of existing pile 3 The operation of extracting the existing pile 3 will be described below with reference to Fig. 4. Fig. 4(a) to (e) are diagrams for explaining the operation of extracting the existing pile using a pile extraction jig. First, the extraction machine 30 will be briefly described.

[0037] As shown in Figs. 4(a) to (e), the extraction machine 30 is, for example, a pile driver, pile extractor, crawler, crawler, or the like, and is equipped with a control room and an engine room on a chassis 30A. An arm 31 is held vertically on the chassis 30A, and the angle of the arm 31 can be changed to an inclined or horizontal state by a hydraulic cylinder. A lifting head 32 is attached to the arm 31 so as to be movable up and down. The lifting head 32 is provided with a chuck mechanism (not shown) for gripping the pile extraction jig 10, and the connector 14 is fixedly connected to the lifting head 32. A drive unit (not shown), such as a hydraulic motor for rotating the pile extraction jig 10 is built into the lifting head 32.

[0038] First, as shown in Fig. 4(a), the pile extraction jig 10 is attached to the extraction machine 30. Specifically, the pile extraction jig 10 can be attached to the extraction machine 30 by connecting the connector 14 shown in Fig. 1 etc. to the lifting head 32 of the extraction machine 30. In this state, the excavation blade 16 fixed to the casing 11 can be directed downward to align the axis of the existing pile 3 with the rotation axis.

[0039] Next, as shown in Figures 4(b) and 4(c), the drilling blade 16 is pushed into the ground G while rotating the casing 11 around the rotation axis, and the drilling blade 16 excavates the ground G around the existing pile 3. As a result, the head of the existing pile 3 is inserted from the opening of the casing 11, and the existing pile 3 can be accommodated inside the casing 11 as the excavation proceeds.

[0040] After the state of Fig. 4(c) is reached, the existing pile 3 housed in the casing 11 is pulled out together with the casing 11, as shown in Fig. 4(d) and Fig. 4(e). Since a plurality of excavation blades 16 are arranged along the periphery of the opening of the casing 11, a minimum amount of ground G can be excavated around the existing pile 3, and therefore, when the existing pile 3 is pulled out together with the casing 11, the ground G can be prevented from loosening and collapsing.

[0041] In order to prevent the existing pile 3 from falling out of the casing 11, the opening of the casing 11 may be covered with a sealing member, and the existing pile 3 may be fixed with a sling or the like through the opening of the casing 11. The backfilling material may be filled into the extraction hole H from the discharge pipe 19 installed in the casing 11 at the same time as the casing 11 is extracted, or may be filled separately after the casing 11 is extracted (without using the discharge pipe 19 installed in the casing 11).

[0042] The existing pile 3 housed in the casing 11 that has been pulled out from the ground G can be easily opened in the axial direction by pivoting the pivot segment 11B relative to the fixed segment 11A by the hinge mechanism 18. This allows the pulled-out existing pile 3 to be easily removed from inside the casing 11. At this time, with the casing 11 open, the existing pile 3 can be removed from the casing 11 by pushing it out from the outside through the long hole 13 of the fixed segment 11A. In this embodiment, the long hole 13 is provided in the fixed segment 11A, but for example, a similar long hole may also be provided in the pivot segment 11B, or a similar long hole may be provided only in the pivot segment 11B. This can be expected to have the same effect as the long hole 13 of the fixed segment 11A.

[0043] After the existing pile 3 is removed from the casing 11, the hinge mechanism 18 pivots the pivot segment 11B relative to the fixed segment 11A in the opposite direction to the above-mentioned direction, thereby closing the inside of the casing 11. In this state, the pivot segment 11B is fixed to the fixed segment 11A by the fixing part 17, making it possible to form a cylindrical casing. This allows the pile extraction jig 10 to be reused.

[0044] Second Embodiment 5 is a schematic perspective view of a pile extraction jig according to a second embodiment of the present invention. The pile extraction jig of this embodiment differs from that of the first embodiment mainly in the configuration of the pivot segment. Therefore, the other configurations are given the same reference numerals and detailed description thereof is omitted.

[0045] As shown in FIG. 5, in this embodiment, the pivot segment 11B is composed of multiple (e.g., two) circumferential segments 11C divided along the circumferential direction of the casing 11, and each of the circumferential segments 11C is connected by a hinge mechanism 18 at the edge 11f of the fixed segment 11A.

[0046] Since the circumferential divided bodies 11C are disposed above and below the casing 11, each circumferential divided body 11C can be pivoted independently with respect to the fixed segment 11A within the casing 11. This allows the interior 11S of the casing 11 to be opened without hindrance even if locally compressed soil C is filled around the existing pile 3. Note that in this embodiment, as long as the circumferential divided bodies 11C can be connected via the hinge mechanism 18, the number of pieces into which the pivot segment 11B is divided is not particularly limited.

[0047] Third Embodiment 6 is a schematic perspective view of a pile extraction jig according to a third embodiment of the present invention. The pile extraction jig of this embodiment differs from that of the first embodiment mainly in the configuration of the pivot segment. Therefore, the other configurations are given the same reference numerals and detailed description thereof is omitted.

[0048] As shown in FIG. 6, in this embodiment, the pivot segment 11B is composed of two axial division bodies 11D divided along the axial direction of the casing 11, and each of the axial division bodies 11D is connected by a hinge mechanism 18 at each edge 11f of the fixed segment 11A.

[0049] Since the two axial division bodies 11D are arranged in the circumferential direction of the casing 11, each axial division body 11D can be pivoted independently with respect to the fixed segment 11A in the casing 11, and the interior 11S of the casing 11 can be opened in a so-called double-opening manner. This allows the interior of the casing 11 to be opened without hindrance even if locally compressed soil C is filled around the existing pile 3. Furthermore, the axial division body 11D may be further divided into a plurality of parts along the circumferential direction. In this case, it is assumed that each of the divided division bodies is connected by a hinge mechanism 18. This configuration allows the interior of the casing 11 to be opened more smoothly.

[0050] [Fourth embodiment] Fig. 7 is a schematic perspective view of a pile extraction jig according to a fourth embodiment of the present invention. Figs. 8(a) to (d) are views showing the positional relationship between the connecting body and the holding member from the pile extraction work to the work of removing the existing pile. Fig. 9 is a schematic perspective view explaining the state in which the casing is opened in the state shown in Fig. 8(d). The pile extraction jig of this embodiment differs from that of the first embodiment mainly in the attachment structure of the top plate and the connecting body. Therefore, the other configurations are given the same reference numerals and detailed description thereof will be omitted.

[0051] 7, in this embodiment, the connecting body 14 is provided with a pair of pins 26 formed on a line perpendicular to the rotation axis CL. The pins 26 are cylindrical and fixed to the connecting body 14 by welding or the like. The pair of pins 26 are held by a pair of holding members 25 fixed to the top plate 15.

[0052] In this embodiment, the holding member 25 has a gate-shaped structure, and a pair of holding members 25 are arranged to sandwich the connecting body 14. Each holding member 25 has a holding hole 27 into which a pin 26 is inserted and which holds the connecting body 14 via the pair of pins 26.

[0053] The holding hole 27 is formed to have a size such that, with the pair of pins 26 inserted, the casing 11 is tiltable relative to the connector 14 and the casing 11 is movable in the axial direction. Specifically, the pins 26 are rotatable relative to the holding member 25 and movable in the axial direction within the holding hole 27 so that the casing 11 can move as described above. Note that, in this embodiment, the tilting range of the casing 11 ranges from a position in which the axial direction is aligned along the vertical direction to a position in which the axial direction is aligned along the horizontal direction, but the tilting range is not limited as long as the interior 11S of the casing 11 can be opened stably.

[0054] As shown in Fig. 8(a), during excavation, the rotational torque, which is the power of the lifting head 32 (of the extraction machine 30), is transmitted to the pair of holding members 25 from a pair of pins 26 provided on the connecting body 14, and the casing 11 rotates around the rotation axis CL. Furthermore, the pushing force, which is the power of the lifting head 32 (of the extraction machine 30), acts on the top plate 15 of the casing 11 via the pair of pins 26.

[0055] As shown in Figure 8 (b), when the casing 11 is pulled out, as the casing 11 moves upward, the pair of pins 26 abut against the upper ends of the retaining holes 27, and the casing 11 can be pulled up via the retaining member 25.

[0056] Thereafter, while maintaining the pair of pins 26 in the holding holes 27 as shown in FIG. 8(b), the excavation blade 16 located at the lower end of the casing 11 is brought into contact with the ground. As shown in FIG. 8(c) and FIG. 8(d), while rotating the holding member 25 around each pin 26, the holding member 25 is lowered together with the connector 14. This allows the casing 11 suspended vertically to be tilted relative to the ground while avoiding interference with the lifting head 32 of the extractor 30. In this embodiment, as shown in FIG. 9, the casing 11 can be brought into a state in which it is laid down on the ground, so that the operator can easily open the casing 11 by pivoting the pivot segment 11B.

[0057] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various design modifications can be made without departing from the spirit of the present invention as described in the claims. [Explanation of symbols]

[0058] 3: existing pile, 10: pile extraction jig, 11: casing, 11A: fixed segment (segment), 11B: pivot segment (segment), 11C: circumferential division body, 11D: axial division body, 14: connection body, 15: top plate, 16: excavation blade, 16a: cutting edge, 16b: first surface, 16c: second surface, 18: hinge mechanism, 25: holding member, 26: pin, 27: holding hole, 30: extraction machine, c: circumscribed circle, CL: rotating shaft, G: ground

Claims

1. A pile extraction tool that is connected to an extraction machine and is rotated by the power of the extraction machine while being pushed into the ground, thereby excavating the ground around the existing pile and then extracting the existing pile. A cylindrical casing that rotates around the axis of the existing pile as a rotation axis, has a top plate fixed to its upper end, and has an opening at its lower end into which the existing pile is inserted; A connector attached to the top plate and connected to the puller; a plurality of digging blades arranged along a periphery of the opening at the lower end of the casing; The casing has a plurality of segments divided along an axial direction of the casing, The plurality of segments include a fixed segment fixed to the top plate; A pile extraction jig characterized in that it is composed of a pivoting segment connected to the fixed segment by a hinge mechanism at an edge formed along the axial direction of the fixed segment so that the inside of the casing can be freely opened and closed.

2. The pile extraction tool described in claim 1, characterized in that the pivot segment is composed of a plurality of circumferentially divided bodies along the circumferential direction of the casing, and each of the circumferentially divided bodies is connected to the edge of the fixed segment by the hinge mechanism.

3. The pile extraction tool according to claim 1, characterized in that the pivot segment is composed of two axially divided bodies divided along the axial direction of the casing, and each of the axially divided bodies is connected by the hinge mechanism at each edge of the fixed segment.

4. The pile extraction jig according to claim 1, characterized in that, when the casing is viewed from the axial direction, the hinge mechanism is arranged inside the circumscribed circle in contact with the multiple drilling blades.

5. The pile extraction tool according to claim 1, characterized in that at least one of the fixed segment and the pivoting segment is formed with at least one long hole extending along the axial direction so as to communicate with the inside of the casing.

6. A pile extraction jig as described in claim 1, characterized in that the cutting edge of the digging blade is positioned closer to the rotation axis than the casing in a cross section passing through the rotation axis, and the cutting edge is formed by a first surface inclined outward with respect to the axial direction and a second surface extending into the casing along the axial direction.

7. The connector is provided with a pair of pins formed on a line perpendicular to the rotation axis, a pair of holding members each having a holding hole into which the pair of pins are inserted and which holds the connector, are fixed to the top plate; The pile extraction jig described in claim 1, characterized in that the retaining hole is formed to a size that allows the casing to be freely tilted and moved in the axial direction relative to the connecting body when the pair of pins are inserted.

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