Pile pulling unit

Abstract

To provide a pile pulling unit capable of easily removing an existing pile housed in a casing from inside the casing.SOLUTION: A pile pulling unit 1A includes a drilling body 10 that rotates around an axis of an existing pile 3 as a rotation axis CL, a cylindrical casing 11A having a lower end opening 11a into which the existing pile 3 is inserted and a storage space 30s for storing the extracted existing pile 3, and a plurality of drilling blades 16 fixed along a periphery of the lower end opening 11a of the casing 11A. The pile pulling unit 1A has a connecting part 25B that can be freely connected to an upper part of the casing 11A so as to rotate around the rotation axis CL together with the drilling body 10 when excavating the ground G, and includes a cylindrical sliding body 20 that slides downward on an inner circumferential surface 11d of the casing 11A along the rotation axis CL when the connection by the connecting part 25B is released.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] The Japan Construction Industry Federation, a general incorporated foundation, has issued "Guidelines on the Handling of Existing Underground Structures." As a result, it has generally become impossible to leave existing piles due to the intention of the orderer, budget, or construction period, increasing the importance of pile extraction.

[0003] Therefore, as a technology of this kind, a pile extraction unit for extracting existing piles driven into the ground has been proposed (see, for example, Patent Document 1). This pile extraction unit is a jig that is connected to an extraction machine such as a pile driver and excavates the ground around the existing pile by being pushed into the ground while rotating with the power of the extraction machine. When extracting the existing pile, the pile extraction unit can be pulled up to the ground with the existing pile housed inside the casing, so that the existing pile can be extracted from the ground.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, since the existing pile is extracted while being housed inside the casing of the pile extraction unit, it is not easy to take out the existing pile inside the casing.

[0006] The present invention has been made in view of such problems, and an object thereof is to provide a pile extraction unit capable of easily taking out an existing pile housed inside a casing from inside the casing.

Means for Solving the Problem

[0007] In view of the above problems, the pile extraction unit according to the present invention is connected to an extraction machine and, while rotating by the power of the extraction machine and pushing it into the ground, after excavating the ground around an existing pile, it is a pile extraction unit for extracting the existing pile, and rotates around the axis of the existing pile as a rotation axis, a cylindrical casing in which a lower end opening into which the existing pile is inserted is formed and a housing space for housing the extracted existing pile is formed, an excavation body including a plurality of excavation blades fixed along the periphery of the lower end opening of the casing, a connection part connected to the extraction machine, and a connection part that can be connected to the upper part of the casing so as to rotate around the rotation axis together with the excavation body during excavation of the ground, and in a state where the connection by the connection part is released, a columnar sliding body that slides downward along the rotation axis on the inner peripheral surface of the casing is provided.

[0008] According to this aspect, in a state where the sliding body is connected to the upper part of the casing by the connecting part, during excavation of the ground, the excavation body can be pushed into the ground while rotating the sliding body around the rotation axis together with the excavation body by the extraction machine. Thereby, the ground around the existing pile can be excavated with a plurality of excavation blades fixed to the excavation body, and the existing pile can be accommodated from the lower end opening of the casing. Next, in a state where the existing pile is accommodated in the casing, the extraction machine pulls up the excavation body together with the sliding body. Thereby, the existing pile accommodated in the excavation body can be extracted from the ground.

[0009] Finally, the connection by the connection part is released, and in this released state, using the extraction machine, the columnar sliding body is slid downward along the rotation axis with respect to the inner peripheral surface of the casing. Thereby, the existing pile accommodated in the housing space of the casing of the excavation body can be easily pushed out from the lower end opening of the casing by the sliding body.

[0010] As a more preferred embodiment, the casing includes a cylindrical outer cylinder, and an inner cylinder in which the accommodation space is formed and which slides along the inner peripheral surface of the outer cylinder within a sliding range along the rotation axis while being accommodated in the outer cylinder. The periphery of the lower end opening of the outer cylinder has the plurality of cutting blades fixed thereto. The outer cylinder is provided with an upper restricting portion that restricts the upward sliding of the inner cylinder along the rotation axis at the lower limit position of the sliding range of the inner cylinder, such that the inner cylinder rotates around the rotation axis together with the outer cylinder, and a lower restricting portion that restricts the downward sliding of the inner cylinder along the rotation axis with respect to the outer cylinder at the upper limit position of the sliding range of the inner cylinder.

[0011] According to this embodiment, the upper restricting portion restricts the upward sliding of the inner cylinder along the rotation axis at the lower limit position of the sliding range of the inner cylinder. With the inner cylinder being rotatable together with the outer cylinder, when excavating the ground, the extraction machine can push the excavation body into the ground while rotating the sliding body around the rotation axis together with the excavation body. Thereby, the ground around the existing pile can be excavated with the plurality of cutting blades fixed to the excavation body, and the existing pile can be accommodated in the inner cylinder from the lower end opening of the inner cylinder.

[0012] Next, with the existing pile accommodated in the inner cylinder, the extraction machine pulls up the excavation body together with the sliding body. Thereby, the existing pile accommodated in the excavation body can be pulled out from the ground. Next, when the restriction by the upper restricting portion is released and the inner cylinder is slid upward with respect to the outer cylinder to the upper limit position of the sliding range of the inner cylinder, the existing pile accommodated in the inner cylinder is also pulled up together with the inner cylinder. In this state, the lower restricting portion restricts the downward sliding of the inner cylinder along the rotation axis at the upper limit position of the sliding range of the inner cylinder.

[0013] Finally, the connection by the connecting part is released, and in this released state, using a pulling machine, a columnar sliding body is slid downward along the rotation axis with respect to the inner peripheral surface of the inner cylinder. Thereby, the existing pile accommodated in the inner cylinder of the excavation body can be easily pushed out from the lower end opening of the inner cylinder to the inside of the outer cylinder by the sliding body.

[0014] In another preferred embodiment, the pile pulling unit further includes a support base having a plurality of support columns for supporting the excavation body, and in the support base, a discharge space for discharging the existing pile accommodated in the accommodation space is formed between the plurality of support columns.

[0015] According to this embodiment, after pulling out the existing pile accommodated in the excavation body from the ground, the excavation body is supported by the support base. While maintaining this supported state, the connection by the connecting part is released, and using a pulling machine, a columnar sliding body is slid downward along the rotation axis with respect to the inner peripheral surface of the casing. Thereby, the existing pile accommodated in the casing of the excavation body can be easily pushed out from the lower end opening of the casing by the sliding body into the discharge space formed between the support columns.

[0016] In a more preferred embodiment, the support base includes a top plate fixed to a plurality of support columns, and a circular opening communicating with the discharge space is formed in the top plate, and the opening has a size such that a plurality of fixed excavation blades are supported at the periphery of the opening.

[0017] According to this embodiment, after pulling out the existing pile accommodated in the excavation body from the ground, a plurality of excavation blades fixed to the casing are supported at the periphery of the opening of the top plate. Thereby, the excavation body can be stably supported by the support base. While maintaining this supported state, the connection by the connecting part is released, and using a pulling machine, a columnar sliding body is slid downward along the rotation axis with respect to the inner peripheral surface of the casing. Thereby, the existing pile accommodated in the casing of the excavation body can be easily pushed out from the lower end opening of the casing by the sliding body into the discharge space formed between the support columns through the opening.

[0018] In yet another preferred embodiment, the excavation body is provided with engagement pins that project horizontally and engage with each of the support columns, and a recess that engages with the engagement pins is formed at the upper end of the support column.

[0019] According to this embodiment, after pulling out the existing pile accommodated in the excavation body from the ground, the engagement pins projecting horizontally are engaged with the recesses at the upper ends of the support columns. Thereby, the excavation body can be stably supported on the support base. While maintaining this supported state, the connection by the connecting portion is released, and using a pulling machine, a columnar sliding body is slid downward with respect to the inner peripheral surface of the casing along the rotation axis. Thereby, the existing pile accommodated in the casing of the excavation body can be easily pushed out from the lower end opening of the casing by the sliding body into the discharge space formed between the support columns.

Advantages of the Invention

[0020] According to the present invention, the existing pile accommodated in the casing can be easily taken out from inside the casing.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Mode for Carrying Out the Invention

[0022] Hereinafter, with reference to Figs. 1 to 12, the pile extraction unit according to several embodiments will be described.

[0023] 〔First Embodiment〕 1. Regarding the pile extraction unit 1A Hereinafter, with reference to Figs. 1 to 4, the pile extraction unit 1A according to the first embodiment will be described.

[0024] The pile extraction unit 1A according to this embodiment is connected to an extraction machine 50 such as a pile driving machine, as shown in FIG. 5 and the like described later, and is pushed into the ground G while rotating by the power of the extraction machine 50, and is a unit that excavates the ground G around the existing pile 3. After excavation, the existing pile 3 is accommodated inside the pile extraction unit 1A, and the existing pile 3 is extracted together with the pile extraction unit 1A. In this embodiment, the pile extraction unit 1A is a jig composed of an excavation body 10 and a sliding body 20 described later. However, in the first and second embodiments described later, the pile extraction units 1B and 1C are composed of an excavation body 10, a sliding body 20, and a support base 70A (70B).

[0025] The existing pile 3 is not particularly limited, such as a wooden pile, a small-diameter steel pipe pile, a precast concrete pile, or a cement milk pile (columnar improvement body). As long as it has a diameter and length that can be accommodated in the casing 11A of the pile extraction unit 1A described later, its size is not limited either.

[0026] 2. Regarding the excavation body 10 As shown in FIGS. 1 and 2, the pile extraction unit 1A includes an excavation body 10 and a sliding body 20. The excavation body 10 includes a casing 11A and a plurality of excavation blades 16. The casing 11A is a cylindrical member. In the casing 11A, a lower end opening 11a is formed that rotates around the axis of the existing pile 3 as the rotation axis CL and into which the existing pile 3 is inserted, and an accommodation space for accommodating the extracted existing pile 3 is formed. A plurality of excavation blades 16 are fixed along the periphery of the lower end opening 11a of the casing 11A. The plurality of excavation blades 16 are arranged on the casing 11A at intervals in the circumferential direction.

[0027] Specifically, in the present embodiment, the casing 11A includes a cylindrical outer cylinder 11 and an inner cylinder 30 that slides on the inner peripheral surface 11d of the outer cylinder 11. As shown in FIG. 2(b), an accommodation space 30s for accommodating the existing pile 3 pulled out is formed in the inner cylinder 30 along the rotation axis CL. As shown in FIG. 2(c), an accommodation space 30s for accommodating the inner cylinder 30 is formed in the outer cylinder 11 along the rotation axis CL, and a plurality of excavation blades 16 are fixed to the periphery of the lower end opening 11a of the outer cylinder 11. Long holes 13 and 33 extending in the axial direction are formed in the outer cylinder 11 and the inner cylinder 30 that constitute the casing 11A.

[0028] As shown in FIG. 1(b), the excavation blade 16 is fixed, for example, by welding or the like in a state where a groove or the like is provided on the upper surface and engaged with the lower end opening 11a of the outer cylinder 11. The cutting edge 16a of the excavation blade 16 is arranged closer to the rotation axis CL than the inner peripheral surface 11d of the outer cylinder 11 in a cross section passing through the rotation axis CL. Specifically, as shown in FIG. 1(c), the cutting edge 16a is formed between a first surface 16b inclined outward with respect to the axial direction and a second surface 16c extending into the casing 11A along the axial direction. In the present embodiment, as shown in FIG. 1(b), when viewed from the direction along the rotation axis CL, a part of the first surface 16b, the cutting edge 16a, and the second surface 16c are arranged inside the circle formed by the inner diameter of the outer cylinder 11.

[0029] In this way, the cutting edge 16a of the excavation blade 16 is arranged closer to the rotation axis CL than the inner peripheral surface 11d of the outer cylinder 11, and in this state, a first surface 16b inclined outward with respect to the axial direction is formed from the cutting edge 16a. Therefore, during the excavation of the extraction operation shown below, it is possible to suppress the excessive entry of the crushed earth and sand C into the casing 11A. As a result, it is possible to suppress the crushed earth and sand C from entering between the inner cylinder 30 of the casing 11A and the existing pile 3 accommodated in the casing 11A in a compressed state, so that the existing pile can be smoothly pushed out from the inner cylinder 30.

[0030] The inner cylinder 30 slides within a predetermined sliding range along the rotation axis CL while being accommodated in the outer cylinder 11. An outer peripheral rib 35 protruding outward along the circumferential direction is formed at the lower end of the outer peripheral surface 30b of the inner cylinder 30, and an inner peripheral rib 15 protruding inward along the circumferential direction is formed at the upper end of the outer cylinder 11.

[0031] At the upper limit position of the sliding range of the inner cylinder 30 shown in FIG. 4, the outer peripheral rib 35 of the inner cylinder 30 shown in FIGS. 2(b) and 2(c) abuts against the inner peripheral rib of the outer cylinder 11. On the other hand, at the lower limit position of the sliding range of the inner cylinder 30 shown in FIGS. 1 and 3, the lower end surface 30a of the inner cylinder 30 shown in FIGS. 2(b) and 2(c) abuts against the cutting edge 16 fixed to the outer cylinder 11. In this way, the inner cylinder 30 can slide on the inner peripheral surface 11d of the outer cylinder 11 within the sliding range along the rotation axis CL.

[0032] Furthermore, in the present embodiment, the outer cylinder 11 is provided with an upward restricting portion (18, 19B) that restricts the upward sliding of the inner cylinder 30 along the rotation axis CL with respect to the outer cylinder 11 when the inner cylinder 30 rotates around the rotation axis CL together with the outer cylinder 11 at the lower limit position of the sliding range of the inner cylinder 30 shown in FIGS. 1 and 3.

[0033] In the present embodiment, the upward restricting portion (18, 19B) is at least composed of an engaging member 18 such as a screw or a pin and a through hole 19B formed in the lower portion of the outer cylinder 11 and engaging with the engaging member 18.

[0034] Here, in the present embodiment, an engagement hole 39 for engaging with the engagement member 18 is formed in the outer peripheral rib 35 of the inner cylinder 30. When the engagement member 18 engages with the engagement hole 39 through the through hole 19B, at the lower limit position of the sliding range of the inner cylinder 30, the inner cylinder 30 can be restricted from sliding upward along the rotation axis CL with respect to the outer cylinder 11 (see FIGS. 3 and 1). When the engagement member 18 is a screw, the engagement member 18 is screwed into the through hole 19B and the engagement hole 39. When the engagement member 18 is a pin, the engagement member 18 is inserted into the through hole 19B and the engagement hole 39. When the engagement member 18 is screwed into the engagement hole 39, the engagement member 18 does not necessarily have to be screwed into the through hole 19B.

[0035] Furthermore, in the present embodiment, on the other hand, at the upper limit position of the sliding range of the inner cylinder 30 shown in FIG. 4, a lower restricting portion (18, 19A) for restricting the inner cylinder 30 from sliding downward along the rotation axis CL with respect to the outer cylinder 11 is provided.

[0036] In the present embodiment, the lower restricting portion (18, 19A) is at least constituted by an engagement member 18 such as a screw or a pin and a through hole 19A formed in the upper part of the outer cylinder 11 and engaging with the engagement member 18.

[0037] In the present embodiment, similar to the upper restricting portion, when the engagement member 18 engages with the engagement hole 39 through the through hole 19A, at the upper limit position of the sliding range of the inner cylinder 30, the inner cylinder 30 can be restricted from sliding upward along the rotation axis CL with respect to the outer cylinder 11 (see FIG. 4). Similar to the upper restricting portion, when the engagement member 18 is a screw, the engagement member 18 is screwed into the through hole 19A and the engagement hole 39. When the engagement member 18 is a pin, the engagement member 18 is inserted into the through hole 19A and the engagement hole 39.

[0038] In this embodiment, since the outer peripheral rib 35 of the inner cylinder 30 is thicker than other parts, even if the engaging hole 39 is provided, the mechanical strength of the engaging hole 39 can be ensured. In this embodiment, the engaging hole 39 is provided in the outer peripheral rib 35 of the inner cylinder 30. However, as long as the state of pressing the end face of the engaging member 18 can be maintained and the sliding downward along the rotation axis CL of the inner cylinder 30 can be restricted, the engaging hole 39 may not be provided in the inner cylinder 30. When the engaging member 18 is screwed into the engaging hole 39, the engaging member 18 may not be screwed into the through hole 19A.

[0039] 3. Regarding the sliding body 20 As shown in FIGS. 1 and 2(a), the sliding body 20 is a columnar member and is a member that slides along the rotation axis CL on the inner peripheral surface 11d of the casing 11A. The diameter of the outer peripheral surface 20b of the sliding body 20 is substantially the same as the diameter of the inner peripheral surface 30d of the inner cylinder 30 of the casing 11A. The sliding body 20 has a connection portion 28 connected to the pulling machine 50. The connection portion 28 is a hexagonal columnar member extending along the rotation axis CL and is fixed to the upper end surface 20c of the cylindrical portion that forms the main body of the sliding body 20.

[0040] In this embodiment, the sliding body 20 has connection portions 25A and 25B that can be connected to the upper and lower portions of the casing 11A so as to rotate around the rotation axis CL together with the excavating body 10 during excavation of the ground G. Specifically, the connection portions 25A and 25B are formed on the outer peripheral surface 20b of the sliding body 20 and are engaging recesses in which the protrusions (keys) 32 (see FIG. 2(b)) formed on the inner peripheral surface 30d of the inner cylinder 30 of the casing 11A are accommodated.

[0041] In this embodiment, on the outer peripheral surface 20b of the sliding body 20, an axial groove 23 that extends from the upper part to the lower part of the sliding body 20 and guides the protrusion 32, and upper and lower circumferential grooves 24A and 24B that extend circumferentially from both ends of the axial groove 23 and guide the protrusion 32 are formed. Further, a locking recess (25A) that extends downward from the circumferential groove 24A and locks the protrusion 32 is formed, and a locking recess (25B) that extends upward from the circumferential groove 24B and locks the protrusion 32 is formed. By locking the protrusion 32 in the locking recess (25A) and the locking recess (25B), the sliding body 20 can be connected to the casing 11A so as to rotate around the rotation axis CL together with the excavating body 10 during excavation of the ground G. In addition to this, the vertical movement of the sliding body 20 and the casing 11A is also restricted.

[0042] Furthermore, if the protrusion 32 is moved from the locking recess (25A) and the locking recess (25B) to the ends of the circumferential grooves 24A and 24B, the connection between the sliding body 20 and the casing 11A is released. If the protrusion 32 is moved to the axial groove 23, the sliding body 20 can be moved vertically with respect to the casing 11A without rotating around the rotation axis CL. In this way, in a state where the connection by the connecting portion 25A is released, the sliding body 20 can slide downward along the rotation axis CL on the inner peripheral surface 30d of the inner cylinder 30 of the casing 11A.

[0043] As a result, in a state where the connection by the connecting portion 25A is released, the sliding body 20 can slide downward along the rotation axis CL on the inner peripheral surface 11d of the inner cylinder 30 of the casing 11A (see, for example, the state shown in FIG. 6(b) to the state shown in FIG. 6(c), or the state shown in FIG. 3 to the state shown in FIG. 1(a)). On the other hand, in a state where the connection by the connecting portion 25B is released, the sliding body 20 can slide upward along the rotation axis CL on the inner peripheral surface 11d of the inner cylinder 30 of the casing 11A (see, for example, the state shown in FIG. 6(a) to the state shown in FIG. 6(b), or the state shown in FIG. 3 to the state shown in FIG. 4).

[0044] 4. Regarding the extraction work of the existing pile 3 Next, with reference to FIGS. 5 and 6, the extraction operation of the existing pile 3 will be described. Here, first, the extractor 50 will be briefly described.

[0045] As shown in FIGS. 5 and 6, the extractor 50 is, for example, a pile driver, a pile extractor, a rafter, a crawler, etc., and has a control room and an engine room on the vehicle body 50A. An arm 51 is held in a vertical state on the vehicle body 50A, and the arm 51 can be angled to an inclined state or a horizontal state by a hydraulic cylinder. A lifting head 52 is mounted on the arm 51 so as to be movable up and down. The lifting head 52 is provided with a chuck mechanism (not shown) for gripping the pile extraction unit 1A, and the connecting portion 28 shown in FIG. 1(a) is connected and fixed to the lifting head 52. A drive unit (not shown) such as a hydraulic motor for rotating the pile extraction unit 1A is incorporated in the lifting head 52.

[0046] First, as shown in FIG. 5(a), the pile extraction unit 1A is attached to the extractor 50. Specifically, the pile extraction unit 1A can be attached to the extractor 50 by connecting the connecting portion 28 shown in FIG. 1 etc. to the lifting head 52 of the extractor 50. In this state, with the excavation blade 16 fixed to the casing 11A facing downward, the axis of the existing pile 3 and the rotation axis can be aligned.

[0047] In this state, the pile extraction unit 1A is in the state shown in FIG. 3, and the upward sliding along the rotation axis CL by the inner cylinder 30 is restricted at the lower limit position of the sliding range of the inner cylinder 30 by the upper regulating portions (18, 19B). In addition to this, the inner cylinder 30 is rotatable around the rotation axis CL together with the outer cylinder 11. The sliding body 20 is connected to the casing 11A so as to rotate around the rotation axis CL together with the excavation body 10 during excavation of the ground G by locking the projection 32 of the inner cylinder 30 of the casing 11A in the locking recess (25B) by the connection by the connecting portion 25B.

[0048] Next, as shown in FIGS. 5(b) and 5(c), while rotating the excavation body 10 around the rotation axis CL, the excavation blade 16 is pushed into the ground G, and the ground G around the existing pile 3 is excavated with the excavation blade 16. As a result, the pile head of the existing pile 3 is inserted from the opening of the casing 11A, and as the excavation progresses, the existing pile 3 can be accommodated in the casing 11A.

[0049] Next, as shown in FIG. 6(a), the existing pile 3 accommodated in the casing 11A is pulled out together with the sliding body 20. Here, since a plurality of excavation blades 16 are arranged along the periphery of the opening of the casing 11A, the minimum amount of ground G around the existing pile 3 can be excavated. Therefore, when pulling out the existing pile 3 together with the casing 11A, it is possible to suppress the ground G from loosening and collapsing.

[0050] Note that the opening of the casing 11A may be covered with a sealing member so that the existing pile 3 does not fall off from the casing 11A, or the existing pile 3 may be fixed with a sling or the like from the opening of the casing 11A. The filling of the backfill material into the extraction hole H may be performed separately after the extraction of the casing 11A.

[0051] Next, as shown in FIG. 6(b), when the regulation by the upper regulation portions (18, 19B) is released and the inner cylinder 30 is slid upward with respect to the outer cylinder 11 to the position of the upper limit of the sliding range of the inner cylinder 30, the existing pile 3 accommodated in the inner cylinder 30 is also pulled up together with the inner cylinder 30.

[0052] In this state, the pile extraction unit 1A is in the state shown in FIG. 4, and the downward sliding of the inner cylinder 30 along the rotation axis CL is regulated by the lower regulation portions (18, 19A) at the position of the upper limit of the sliding range of the inner cylinder 30.

[0053] Next, as shown in FIG. 6(c), the connection by the connecting portion 25B is released, and the engagement of the protrusion 32 of the inner cylinder 30 of the casing 11A with the locking recess (25B) is released. Specifically, the casing 11A is rotated around the rotation axis CL with respect to the sliding body 20 so that the protrusion 32 of the inner cylinder 30 is positioned at the lower end of the axial groove 23 of the sliding body 20. In this released state, using the pulling-out machine 50, the columnar sliding body 20 is slid downward with respect to the inner peripheral surface 30d of the inner cylinder 30 along the rotation axis CL. As a result, the existing pile 3 accommodated in the inner cylinder 30 of the excavation body 10 can be easily pushed out from the lower end opening of the inner cylinder 30 to the inside of the outer cylinder 11 by the tip surface 20a of the sliding body 20. By repeating such an operation, the existing pile 3 can be pulled out.

[0054] 〔Second Embodiment〕 Hereinafter, the pile pulling-out units 1B and 1C according to the second embodiment and its modified examples will be described. The points in which the second embodiment differs from the first embodiment are that the casing 11A is not divided into the inner cylinder 30 and the outer cylinder 11 but is made into one integrated casing, and a support base 70A (70B) is newly provided. Therefore, the same components as those in the first embodiment are denoted by the same reference numerals and their details will be described.

[0055] As shown in FIGS. 7 and 8, the casing 11A is a cylindrical member. In the casing 11A, a lower end opening 11a is formed that rotates around the rotation axis CL of the existing pile 3 and into which the existing pile 3 is inserted, and a storage space 11s for storing the pulled-out existing pile 3 is formed. A plurality of excavation blades 16 are fixed along the periphery of the lower end opening 11a of the casing 11A. The plurality of excavation blades 16 are arranged on the casing 11A at intervals in the circumferential direction. Similar to the first embodiment, protrusions 32 that engage with the locking recess 25A and the locking recess 25B are formed on the inner peripheral surface 11d of the casing 11A.

[0056] As shown in Fig. 9(a), in the present embodiment, the pile extraction unit 1B further includes a support base 70A having a base plate 71 and a plurality of support columns 72 that stand upright from the base plate 71 and support the excavation body 10. In the support base 70A, a discharge space 70s for discharging the existing pile 3 accommodated in the accommodation space 11s (see Fig. 8) is formed between the plurality of support columns 72. In the present embodiment, the support base 70A includes two support columns 72, but the number of support columns 72 is not limited to this as long as the excavation body 10 can be supported and the discharge space 70s can be formed.

[0057] Specifically, the support base 70A includes a top plate 74 fixed to the plurality of support columns 72, and a circular opening 74a communicating with the discharge space 70s is formed in the top plate 74. As shown in Fig. 9(b), the opening 74a is sized such that a plurality of excavation blades 16 fixed to the peripheral edge 74b of the opening 74a are supported by the peripheral edge 74b of the opening 74a. Specifically, the opening 74a is formed such that the first surface 16b of the excavation blade 16 that is inclined outward with respect to the axial direction abuts against the peripheral edge 74b of the opening 74a.

[0058] According to the present embodiment, after the existing pile 3 accommodated in the excavation body 10 is pulled out from the ground G, the first surface 16b of the plurality of excavation blades 16 fixed to the casing 11A is supported on the peripheral edge 74b of the opening 74a of the top plate 74. Thereby, the excavation body 10 can be stably supported on the support base 70A. While maintaining this supported state, from the state shown in Fig. 8, the connection by the connecting portion 25B is released, and using the extraction machine 50, the cylindrical sliding body 20 is slid downward along the rotation axis CL with respect to the inner peripheral surface 11d of the casing 11A to the state shown in Fig. 7. As a result, the existing pile 3 accommodated in the casing 11A of the excavation body 10 can be easily pushed out from the lower end opening 11a of the casing 11A by the sliding body 20 into the discharge space 70s formed between the support columns 72 through the opening 74a.

[0059] Figures 10 to 12 are modified examples of the pile extraction unit 1C according to the second embodiment. The differences between this modified example and the pile extraction unit 1B shown in Figures 7 to 9 are that an engagement pin 17A is provided at the upper part of the casing 11A via a bracket 17B, the structure of the support columns 73 of the support base 70B, and no top plate is provided on the support base 70B. Therefore, the same components as those in the second embodiment shown in Figures 7 to 9 are denoted by the same reference numerals and their details will be described.

[0060] In this embodiment, the casing 11A of the excavation body 10 is provided with columnar engagement pins 17A that project horizontally from the excavation body 10 and engage with the respective support columns 72. In this embodiment, two engagement pins 17A are formed with the rotation axis CL interposed therebetween. Each engagement pin 17A is disposed above the upper end surface 11c via a bracket 17B fixed to the upper end surface 11c of the casing 11A. If the engagement pin 17A can be attached to the casing 11A of the excavation body 10 via the bracket 17B, the engagement pin 17A may be directly attached to the outer peripheral surface 11b of the casing 11A without using the bracket 17B. Also, if the excavation body 10 can be supported on the support base 70B by the engagement pins 17A, the number of the engagement pins 17A and the support columns 73 is not particularly limited.

[0061] As shown in Figure 12, the support base 70B has semi-circular recesses 73c formed at the upper ends 73b of the support columns 73, 73 for engaging with the engagement pins 17A. The lengths of the support columns 73, 73 are such that a discharge space 70s for discharging the existing pile 3 can be formed between the support columns 73, 73 in a state where the excavation body 10 is supported on the support base 70B.

[0062] According to this modification example, after pulling out the existing pile 3 accommodated in the excavation body 10 from the ground G, the engagement pin 17A is engaged with the recess 73c of the upper end 73b of the support column 73. Thereby, the excavation body 10 can be stably supported on the support base 70B. While maintaining the support state shown in FIG. 11, the connection by the connecting portion 25B is released, and using the pulling machine 50, the columnar sliding body 20 is slid downward along the rotation axis CL with respect to the inner peripheral surface 11d of the casing 11A to the state shown in FIG. 12. As a result, the existing pile 3 accommodated in the casing 11A of the excavation body 10 can be easily pushed out from the lower end opening 11a of the casing 11A by the sliding body 20 into the discharge space 70s formed between the support columns 73, 73.

[0063] As described above, the embodiments of the present invention have been described in detail. However, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the spirit of the present invention described in the claims.

Explanation of Reference Numerals

[0064] 1A, 1B, 1C: Pile pulling unit, 10: Excavation body, 11A: Casing, 11: Outer cylindrical body, 16: Excavation blade, 17A: Engagement pin, 18: Engagement member (upper regulating portion, lower regulating portion), 19A: Through hole (lower regulating portion), 19B: Through hole (upper regulating portion), 30: Inner cylindrical body, 30s: Accommodation space, 70A, 70B: Support base, 70s: Discharge space, 72, 73: Support column, 74: Top plate, CL: Rotation axis, G: Ground

Claims

1. A pile extraction unit that is connected to an extraction machine and rotates by the power of the extraction machine while being pushed into the ground to excavate the ground around an existing pile and then extract the existing pile, a cylindrical casing that rotates about the axis of the existing pile as a rotation axis, forms a lower end opening into which the existing pile is inserted, and forms a storage space for storing the extracted existing pile; and a plurality of excavation blades fixed along the periphery of the lower end opening of the casing, an excavation body comprising; a connection portion connected to the extraction machine; and a connection portion that can be connected to the upper portion of the casing so as to rotate around the rotation axis together with the excavation body during excavation of the ground. In a state where the connection by the connection portion is released, a columnar sliding body that slides downward along the inner peripheral surface of the casing along the rotation axis; A pile extraction unit characterized by comprising.

2. The casing includes a cylindrical outer cylinder, an inner cylinder in which the storage space is formed and that slides on the inner peripheral surface of the outer cylinder within a sliding range along the rotation axis while being accommodated in the outer cylinder, the periphery of the lower end opening of the outer cylinder is provided with the plurality of excavation blades, on the outer cylinder, at the lower limit position of the sliding range of the inner cylinder, the inner cylinder rotates around the rotation axis together with the outer cylinder, and an upper restriction portion that restricts the upward sliding of the inner cylinder along the rotation axis with respect to the outer cylinder; The pile extraction unit according to claim 1, wherein at the upper limit position of the sliding range of the inner cylinder, a lower restriction portion that restricts the downward sliding of the inner cylinder along the rotation axis with respect to the outer cylinder is provided.

3. The pile extraction unit further includes a support base having a plurality of support columns for supporting the excavation body, The support base is characterized in that a discharge space for discharging the existing pile accommodated in the accommodation space is formed between the plurality of support columns. The pile extraction unit according to claim 1.

4. The support base includes a top plate fixed to a plurality of support columns, a circular opening communicating with the discharge space is formed in the top plate, The pile extraction unit according to claim 3, wherein the opening has a size such that the plurality of fixed excavation blades are supported on the periphery of the opening.

5. The excavating body is provided with engaging pins that project horizontally and engage with each of the support columns. The pile extraction unit according to claim 3, wherein a recess that engages with the engaging pin is formed at the upper end of the support column.

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