Pile extraction tip tool

Abstract

To provide a pile extraction tip tool capable of driving a falling prevention claw for preventing falling when a pile is drawn, without using a driving device such as a hydraulic cylinder.SOLUTION: A falling prevention claw 12 of a pile extraction tip tool 1 is rotatable around a vertical shaft part 10a provided on a cylindrical wall part 10 of the pile extraction tip tool 1, and has: an outside part 121 positioned outside the cylindrical wall part 10 from the vertical shaft part 10a; and an inside part positioned inside the cylindrical wall part 10 from the vertical shaft part 10a, wherein at the time of rotation of the excavation, the outside part 121 receives resistance of soil, the falling prevention claw 12 is rotated in a direction at which the inside part 122 is positioned near an inner surface side of the cylindrical wall part 10, on the other hand, by rotation in a direction inverse to the rotation of the excavation when a pile 3 is drawn, the outside part 121 receives the resistance of the soil, the falling prevention claw 12 is rotated in a direction at which the inside part 122 is separated from the cylindrical wall part 10, and the inside part 122 is positioned below the pile 3.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a pile extractor tip used for extracting piles embedded in the ground. [Background technology]

[0002] Patent Document 1 discloses a pile extraction method for extracting a pile embedded in the ground for supporting a structure without damaging the ground. Patent Document 2 discloses a pile extraction device that includes a chuck claw attached to the bottom of a cylindrical casing that is driven into the pile so as to protrude below the bottom end of the pile. The chuck claw is driven by a hydraulic cylinder. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-183501 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-154541 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the technology described in Patent Document 2 has the drawback of requiring a complicated and expensive mechanism because the chuck claws that prevent the pile from falling off when it is pulled out are driven by a hydraulic cylinder.On the other hand, the technology described in Patent Document 1 does not use the chuck claws described above, so there is a risk that the pile may fall off when it is pulled out.

[0005] In view of the above circumstances, an object of the present invention is to provide a pile pulling tip tool that can drive a fall-off prevention claw that prevents a pile from falling off when it is pulled out, without using a driving device such as a hydraulic cylinder. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the pile extractor tip tool according to the present invention is a cylindrical pile extractor tip tool that is positioned at the tip side of a cylindrical ground-penetrating member that is inserted into the ground, excavates the soil around a pile buried in the ground by rotating an excavation blade around the cylindrical axis of the ground-penetrating member, and, with the pile housed inside the ground-penetrating member, positions a fall-off prevention claw below the pile and pulls out the pile together with the ground-penetrating member, The fall-off prevention claw is rotatable around a vertical shaft portion provided on the cylindrical wall portion of the pile pulling tip tool, and has an outer portion located outside the cylindrical wall portion relative to the vertical shaft portion, and an inner portion located inside the cylindrical wall portion relative to the vertical shaft portion, During the rotation for the excavation, the outer portion receives resistance from the soil, and the fall-off prevention claw rotates in a direction in which the inner portion is positioned closer to the inner surface of the cylindrical wall portion. When the pile is pulled out, the outer portion is rotated in the opposite direction to the rotation of the excavation, and the anti-fall-off claw rotates in the direction in which the inner portion moves away from the cylindrical wall portion, so that the inner portion is positioned below the pile.

[0007] With the above configuration, when the pile extracting tip tool rotates during excavation, the inner portion of the anti-fall-off claw is positioned toward the inner surface of the cylindrical wall portion, so the inner portion does not come into contact with the outer periphery of the pile. On the other hand, when the pile extracting tip tool rotates to extract the pile, the inner portion is separated from the cylindrical wall portion and positioned below the pile, so that the pile can be prevented from falling off when extracted. Furthermore, since a driving device such as a hydraulic cylinder for operating the anti-fall-off claw is not required, a simple structure and low costs can be achieved.

[0008] The digging blade may have an outer cutter portion that protrudes outward beyond the outer peripheral surface of the cylindrical wall portion, and the end of the outer portion of the anti-slip claw may be positioned beyond the outer end of the outer cutter portion of the digging blade. In this way, the end of the outer portion of the anti-slip claw receives resistance from the portion of the soil that is not excavated by the outer cutter portion, allowing the anti-slip claw to rotate accurately.

[0009] The digging blade may have an inner cutting edge that protrudes inward from the inner peripheral surface of the cylindrical wall, and the end of the inner portion of the anti-slip claw may be positioned so as not to protrude from the inner cutting edge of the digging blade during the digging. This reduces wear on the inner portion of the anti-slip claw caused by soil portions that are not excavated by the inner cutting edge during the digging.

[0010] The end of the outer portion of the anti-slip claw when the pile is pulled out may be positioned farther from the outer surface of the cylindrical wall than the end of the outer portion when the pile is excavated. This allows the end of the outer portion of the anti-slip claw to withstand a greater resistance from the portion of the soil not excavated by the outer cutter portion than during the excavation, and allows the inner portion to be accurately positioned below the pile when the pile is pulled out.

[0011] A first receiving portion that receives an end of the outer portion during the excavation may be located on the outer surface of the cylindrical wall portion. This makes it possible to prevent the outer portion of the fall-off prevention claw from being damaged by soil pressure during the excavation.

[0012] A second receiving portion that receives an end of the outer portion when the pile is pulled out may be located on the outer surface of the cylindrical wall portion. This makes it possible to prevent the outer portion of the anti-fall-off claw from being damaged by soil pressure when the pile is pulled out.

[0013] The pile-side surface of the inner portion of the anti-fall-off claw may be an arc-shaped concave surface, and during the excavation, the arc-shaped concave surface may form part of the inner curved surface of the cylindrical wall portion. This makes it possible to suppress wear on the pile-side surface of the inner portion.

[0014] The outer and inner portions may be connected by a rib, which can increase the strength of the anti-detachment claw.

[0015] The pile extracting tip may be detachable from the ground-penetrating member, which allows the ground-penetrating member to be used continuously while only the pile extracting tip is replaced.

[0016] The pile extractor tip may be integrally provided with the earth penetrating member, which allows the entire integrated pile extractor to be manufactured at relatively low cost.

[0017] A housing portion for housing the inner portion located near the inner surface of the cylindrical wall portion may be formed in the cylindrical wall portion, and the outer peripheral surface portion of the cylindrical wall portion may protrude outward more than the other outer peripheral surface portions at the housing portion and its vicinity. This allows the pile extractor tip tool to be made thin-walled, thereby reducing the weight of the pile extractor tip tool. On the other hand, a housing portion for housing the inner portion during excavation may be formed in the cylindrical wall portion, and the cylindrical wall portion may be thick enough to prevent the outer peripheral surface portion of the cylindrical wall portion from protruding outward at the location where the housing portion is formed. This allows the entire pile extractor tip tool to be made thick-walled, thereby improving the strength of the pile extractor tip tool. [Effects of the Invention]

[0018] The present invention can more reliably prevent piles from falling off when pulled out than using sling members, and also eliminates the need for driving devices such as hydraulic cylinders, resulting in a simple structure and reduced costs. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is an explanatory diagram showing a pile extraction operation using a heavy machine equipped with a pile extraction tool having a pile extraction tip tool according to an embodiment. FIG. [Figure 2] Figure 1A is an explanatory diagram showing a pile extractor equipped with a thin-type pile extractor tip, and Figure 1B is an explanatory diagram showing a pile extractor equipped with a thick-type pile extractor tip. [Figure 3]Figure 1A is a perspective view showing a thin-walled type stake extractor tip tool according to an embodiment, Figure 1B is a perspective half view of Figure 1A, Figure 1C is a cross-sectional perspective view of Figure 1B, Figure 1D is a cross-sectional perspective view showing the state in Figure 1C where the anti-fall-out claw protrudes toward the stake, Figure 1E is a plan view corresponding to Figure 1C, and Figure 1F is a plan view corresponding to Figure 1D. [Figure 4] Figure 1A is a perspective view showing a thick-walled type stake extractor tip tool according to an embodiment, Figure 1B is a perspective half view of Figure 1A, Figure 1C is a cross-sectional perspective view of Figure 1B, Figure 1D is a cross-sectional perspective view of Figure 1C showing the state in which the anti-fall-out claws protrude toward the stake, Figure 1E is a plan view corresponding to Figure 1C, and Figure 1F is a plan view corresponding to Figure 1D. [Figure 5] 10A and 10B are explanatory views showing the difference in the amount of protrusion of the outer portion due to the rotation of the fall-off prevention claw of the pile pulling tip tool according to the embodiment. [Figure 6] Figure 1A is a perspective view showing a thin-walled type stake extractor tip tool according to another embodiment, Figure 1B is a perspective half view of Figure 1A, Figure 1C is a cross-sectional perspective view of Figure 1B, Figure 1D is a cross-sectional perspective view showing the state in Figure 1C where the anti-fall-out claws protrude toward the stake, Figure 1E is a plan view corresponding to Figure 1C, and Figure 1F is a plan view corresponding to Figure 1D. [Figure 7] Figure 1A is a perspective view showing a thin-walled type stake extractor tip tool according to another embodiment, Figure 1B is a perspective half view of Figure 1A, Figure 1C is a cross-sectional perspective view of Figure 1B, Figure 1D is a cross-sectional perspective view showing the state in Figure 1C where the anti-fall-out claws protrude toward the stake, Figure 1E is a plan view corresponding to Figure 1C, and Figure 1F is a plan view corresponding to Figure 1D. [Figure 8]Figure 1A is a perspective view showing a thin-walled type stake extractor tip tool according to another embodiment, Figure 1B is a perspective half view of Figure 1A, Figure 1C is a cross-sectional perspective view of Figure 1B, Figure 1D is a cross-sectional perspective view showing the state in Figure 1C where the anti-fall-out claws protrude toward the stake, Figure 1E is a plan view corresponding to Figure 1C, and Figure 1F is a plan view corresponding to Figure 1D. DETAILED DESCRIPTION OF THE INVENTION

[0020] (Embodiment 1) An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a cylindrical pile extractor 2 for extracting a pile 3 from the ground attached to a heavy machine 4 (such as a pile driver, pile extractor, crawler, or crawler). The pile extractor 2 has a structure in which a cylindrical earth-penetrating member 20 is inserted into the ground and a pile extractor tip 1 according to the embodiment is attached to the tip of the member. Pile extraction work involves three steps: an excavation step in which the pile extractor 2 is rotated to penetrate the ground; a holding step in which the pile 3 is held by the pile extractor tip 1 after penetration; and an extraction step in which the pile extractor 2 is rotated in the reverse direction to extract the pile 3 from the ground. Examples of piles 3 that can be extracted include small-diameter steel pipe piles, precast concrete piles, wooden piles, and cement piles. If the earth-penetrating member 20 becomes clogged with soil, making excavation impossible, the member can be withdrawn, the soil removed, and excavation can be repeated.

[0021] The pile extraction tool 2 may be a thin-walled type in which the cylindrical wall 21 of the earth-penetrating member 20 and the cylindrical wall 10 of the pile extraction tip tool 1 constituting the pile extraction tool 2 are thin-walled, as shown in FIG. 2(A), or a thick-walled type in which the cylindrical wall 21 of the earth-penetrating member 20 and the cylindrical wall 10 of the pile extraction tip tool 1 are thick-walled, as shown in FIG. 2(B). The pile extraction tool 2 may be provided with a pipe 201 on its outer periphery, and water may be discharged from the pipe 201 during the excavation process to soften the soil around the pile 3 and facilitate the excavation. During the extraction process, backfill material may be discharged from the pipe 201 to expedite the extraction and backfilling of the pile 3. The water and backfill material may be discharged through a separate pipe instead of the pipe 201. The cylindrical wall 21 of the earth-penetrating member 20 may be formed with a plurality of vertically elongated openings 21a, and these openings 21a may facilitate the discharge of excavated soil between the cylindrical wall 21 and the pile 3.

[0022] More specifically, as shown in Figures 3(A) to 3(F) and 4(A) to 4(F), the pile extractor tip tool 1 has a digging blade 11 at the lower end of the pile extractor tip tool 1, and by rotating the digging blade 11 around the cylindrical axis of the earth-penetrating member 20, the soil around the pile 3 buried in the ground is excavated, and with the pile 3 housed inside the earth-penetrating member 20, fall-prevention claws 12 are positioned below the pile 3 to prevent it from falling off, and the pile 3 is pulled out together with the earth-penetrating member 20. For example, two fall-prevention claws 12 are provided, arranged 180 degrees apart and facing each other, but the configuration is not limited to this, and three fall-prevention claws 12 may be provided, for example, spaced 120 degrees apart.

[0023] The excavation blade 11 has an outer cutting edge 11a that protrudes outward from the outer circumferential surface of the cylindrical wall portion 10, and an inner cutting edge 11b that protrudes inward from the inner circumferential surface of the cylindrical wall portion 10.

[0024] The fall prevention claw 12 is rotatable around a vertical shaft 10a provided on the cylindrical wall 10 of the pile puller tip tool 1, and has an outer portion 121 located outside the cylindrical wall 10 relative to the vertical shaft 10a, and an inner portion 122 located closer to the cylindrical wall 10 than the vertical shaft 10a.

[0025] When the pile extractor tip tool 1 rotates during excavation, the outer portion 121 of the fall-prevention claw 12 receives resistance from the soil, and the inner portion 122 rotates in a direction that positions it closer to the inner surface of the cylindrical wall portion 10. During this excavation, the end of the outer portion 121 of the fall-prevention claw 12 is positioned beyond the outer end of the outer cutting portion 11a of the excavation blade 11. On the other hand, when the pile extractor tip tool 1 rotates in the opposite direction to the rotation during excavation as described above, the outer portion 121 receives resistance from the soil, and the fall-prevention claw 12 rotates in a direction that moves the inner portion 122 away from the cylindrical wall portion 10, and the inner portion 122 can be positioned below the pile 3.

[0026] In this embodiment, the angle formed between the outer portion 121 and the inner portion 122 of the fall-prevention claw 12 on the side of the outer portion 121 that receives soil pressure during the excavation is somewhat narrower than 180 degrees, and during the excavation, the inner portion 122 is positioned so as not to protrude from the inner cutting edge 11b of the excavation blade 11 in a plan view, while the outer portion 121 is inclined toward the surface of the cylindrical wall portion 10, so as to receive and deflect soil resistance. When the pile 3 is pulled out, the outer portion 121 receives soil resistance in a direction away from the surface of the cylindrical wall portion 10, causing the fall-prevention claw 12 to rotate, and the outer portion 121 becomes upright, making it more susceptible to soil resistance.

[0027] The cylindrical wall portion 10 is formed with a housing portion 10b that houses an inner portion 122 located closer to the inner surface of the cylindrical wall portion 10. In the thin-walled type, the outer peripheral surface of the cylindrical wall portion 10 at and near the housing portion 10b protrudes outward more than the other outer peripheral surface portions, and the cylindrical wall portion 10 is thicker in the protruding portion excluding the housing portion 10b. On the other hand, in the thick-walled type, the cylindrical wall portion 10 is thick enough to form the portion where the housing portion 10b is formed without causing the outer peripheral surface of the cylindrical wall portion 10 to protrude outward. In other words, while the entire cylindrical wall portion 10 is thick, only the cylindrical wall portion 10 at the housing portion 10b is thinner than the other portions.

[0028] In the thin-walled type, a first convex receiving portion 10c that receives the end of the outer portion 121 during the excavation is provided on the outer surface of the cylindrical wall portion 10. Similarly, in the thick-walled type, a first receiving portion 10c that receives the end of the outer portion 121 during the excavation is provided on the outer surface of the cylindrical wall portion 10.

[0029] In the thin-walled type, a convex second receiving portion 10d is located on the outer surface of the cylindrical wall portion 10 to receive the end of the outer portion 121 when the pile 3 is pulled out. Similarly, in the thick-walled type, a convex second receiving portion 10d is located on the outer surface of the cylindrical wall portion 10 to receive the end of the outer portion 121 when the pile 3 is pulled out.

[0030] The surface of the inner portion 122 of the fall-prevention claw 12 facing the pile 3 forms an arc-shaped concave surface, and during the excavation, the arc-shaped concave surface forms part of the inner curved surface of the cylindrical wall portion 10. That is, with the inner portion 122 accommodated in the accommodation portion 10b, a circular inner surface is formed on the inner periphery of the cylindrical wall portion 10.

[0031] With the pile extractor tip tool 1 having the above configuration, when the pile extractor tip tool 1 rotates during the excavation, the inner portion 122 of the fall-prevention claw 12 is positioned closer to the inner surface of the cylindrical wall portion 10, so the inner portion 122 does not come into contact with the outer periphery of the pile 3. On the other hand, when the pile extractor tip tool 1 rotates to extract the pile 3, the inner portion 122 is separated from the cylindrical wall portion 10 and positioned below the pile 3, so that the pile 3 can be prevented from falling off when extracted. Furthermore, since a driving device such as a hydraulic cylinder for operating the fall-prevention claw 12 is not required, a simple structure can be achieved and costs can be reduced.

[0032] When the digging blade 11 has an outer cutter portion 11a that protrudes outward from the outer peripheral surface of the cylindrical wall portion 10, the digging of the soil by the outer cutter portion 11a can reduce the resistance of the soil on the outer peripheral side of the pile extractor tip tool 1 and the earth penetrating member 20 when pulling out the pile 3. Furthermore, when the end of the outer portion 121 of the fall-off prevention claw 12 is positioned beyond the outer end of the outer cutter portion 11a of the digging blade 11, the end of the outer portion 121 of the fall-off prevention claw 12 receives resistance from the part of the soil that is not excavated by the outer cutter portion 11a, and the fall-off prevention claw 12 can be rotated accurately.

[0033] When the digging blade 11 has an inner cutting edge 11b that protrudes inward from the inner peripheral surface of the cylindrical wall 10, the resistance of the soil portion on the inner peripheral side of the cylindrical wall 10 is reduced by the digging of the soil by this inner cutting edge 11b, and the inner portion 122 can be accurately positioned below the pile 3 when the pile 3 is pulled out. Furthermore, if the end of the inner portion 122 of the fall-off prevention claw 12 is positioned so as not to protrude from the inner cutting edge 11b of the digging blade 11 in a plan view during the above-mentioned digging, it is possible to prevent the inner portion 122 from being damaged by the portion of the soil that is not excavated by the inner cutting edge 11b during this digging.

[0034] The surface of the inner portion 122 of the anti-fall-off claw 12 facing the pile 3 is an arc-shaped concave surface, and when this arc-shaped concave surface forms part of the inner curved surface of the cylindrical wall portion 10 during the excavation, wear and tear on the surface of the inner portion 122 facing the pile 3 can be suppressed.

[0035] When the first receiving portion 10c that receives the end of the outer portion 121 during the excavation is positioned on the outer surface of the cylindrical wall portion 10, it is possible to prevent the outer portion 121 of the fall-prevention claw 12 from being damaged by soil pressure during the excavation. Furthermore, the first receiving portion 10c can prevent the excavated soil from hitting the outer portion 121 when the pile 3 is pulled out, which can also reduce wear and tear on the outer portion 121. Note that in a structure that does not have the first receiving portion 10c, the inner portion 122 can hit the surface of the storage portion 10b during the excavation, stopping the rotation of the fall-prevention claw 12.

[0036] Furthermore, if the second receiving portion 10d that receives the end of the outer portion 121 when the pile 3 is pulled out is located on the outer surface of the cylindrical wall portion 10, it is possible to prevent the outer portion 121 of the fall-off prevention claw 12 from being damaged by the pressure of the soil when the pile 3 is pulled out. Furthermore, since the second receiving portion 10d can prevent the excavated soil from hitting the outer portion 121 during the above-mentioned excavation, it is possible to reduce wear and tear on the outer portion 121.

[0037] The end of the outer portion 121 is positioned beyond the outer end of the outer cutter portion 11a of the digging blade 11 even during the above-mentioned excavation, but when the pile 3 is extracted, as shown in Fig. 5, the end of the outer portion 121 is positioned farther from the outer surface of the cylindrical wall portion 10 than the end of the outer portion 121 during the above-mentioned excavation. In other words, the circle C1 described by the end of the outer portion 121 when the pile 3 is extracted is made larger than the circle C2 described by the end of the outer portion 121 during the above-mentioned excavation. This allows the end of the outer portion 121 of the fall-prevention claw 12 to withstand a greater resistance from the portion of the soil not excavated by the outer cutter portion 11a than during the above-mentioned excavation, and the fall-prevention claw 12 can be reliably rotated to accurately position the inner portion 122 below the pile 3 when the pile 3 is extracted.

[0038] (Embodiment 2) Another embodiment of the present invention will now be described with reference to the accompanying drawings. As shown in Fig. 6, in the pile puller tip 1 of this embodiment, the outer portion 121 and the inner portion 122 are connected by a rib portion 123. The rib portion 123 has a generally triangular shape that extends in a generally linear manner from the outer end of the outer portion 121 to the inner portion 122.

[0039] The storage section 10b is shaped to have a partial opening to avoid contact with the rib section 123. The formation of this opening also results in a structure that does not have a second receiving section 10d. The rotation of the fall-prevention claw 12 when the pile 3 is pulled out is prevented by the inner section 122 coming into contact with a section near the first receiving section 10c (see also embodiment 3).

[0040] In the case of the stake puller tip tool 1 of this embodiment, the rib portion 123 improves the strength of the fall-off prevention claws 12.

[0041] The pile extractor tip tool 1 shown in FIG. 6 is the thin-walled type described above, but even in the case of the thick-walled type described above, it can be configured to have a rib portion 123 and the like.

[0042] (Embodiment 3) Another embodiment of the present invention will be described below with reference to the accompanying drawings. As shown in Fig. 7, in the pile extractor tip tool 1 of this embodiment, the fall-off prevention claw 12 also has an outer portion 121 and an inner portion 122 connected by a rib portion 123. The inner portion 122 extends linearly without curvature. The inner portion 122 is positioned so as not to protrude from the inner cutting edge portion 11b of the excavation blade 11 in plan view. The storage portion 10b has a shape that is partially open to avoid contact with the rib portion 124.

[0043] Furthermore, in the pile extracting tip tool 1 of this embodiment, the rotation of the fall-off prevention claw 12 when the pile 3 is extracted can be prevented by the inner portion 122 coming into contact with the portion near the first receiving portion 10c.

[0044] The pile extractor tip tool 1 shown in FIG. 7 is the thin-walled type described above, but even in the case of the thick-walled type described above, it can be configured to have a rib portion 123 and the like.

[0045] (Embodiment 4) Another embodiment of the present invention will be described below with reference to the accompanying drawings. As shown in Fig. 8, in the pile extractor tip tool 1 of this embodiment, the outer portion 121 of the fall-off prevention claw 12 has a longer protruding length than in the previous embodiment, and the inner portion 122 extends linearly. The outer portion 121 and the inner portion 122 are connected by a large, fan-shaped rib portion 124. The inner portion 122 is positioned so as not to protrude beyond the inner cutting edge portion 11b of the excavation blade 11 in plan view. The storage portion 10b has an opening shape to avoid contact with the rib portion 124.

[0046] In the pile extractor tip tool 1 of this embodiment, the outer portion 121 has a longer protruding length than the previous embodiment, so that when the pile 3 is extracted, the outer portion 121 receives a large resistance from the unexcavated soil, allowing the fall-prevention claws 12 to rotate accurately and position the inner portion 122 below the pile 3. Meanwhile, during the above-mentioned excavation, the outer portion 121 is inclined toward the surface side of the cylindrical wall portion 10, and is able to flush away the soil while receiving resistance from the soil.

[0047] In addition, in the pile extracting tip tool 1 of this embodiment, when the pile 3 is extracted, the rotation of the fall-off prevention claw 12 is stopped by the inner portion 122 coming into contact with the portion on the side of the first receiving portion 10c.

[0048] The pile extractor tip tool 1 shown in FIG. 8 is the thin-walled type described above, but even in the case of the thick-walled type described above, it can be configured to have the rib portion 124 and the like.

[0049] In these pile extractor tip tools 1, it is desirable that the protruding length of the outer portion 121 of the anti-fall-off claw 12 be changed according to the hardness of the ground to be excavated or according to whether or not water is injected. That is, when the ground is soft and there is a risk that the anti-fall-off claw 12 will not rotate properly, it is possible to use an anti-fall-off claw 12 with a long protruding length of the outer portion 121. Also, for example, a structure may be adopted in which an extension member for increasing the length of the outer portion 121 is attached to the tip side of the outer portion 121 and fixed by screwing a bolt into a bolt hole formed on the tip side of the outer portion 121, thereby making it possible to change the protruding length of the outer portion 121.

[0050] Furthermore, in the pile extraction tool 2 described above, the pile extraction tip tool 1 may be detachable from the earth-penetrating member 20. This makes it possible to continue using the earth-penetrating member 20 while replacing only the pile extraction tip tool 1, thereby reducing operating costs. Attachment and detachment can be performed, for example, by providing flange portions at the joints of the pile extraction tip tool 1 and the earth-penetrating member 20, and inserting bolts into the bolt insertion holes of these flanges and tightening nuts.

[0051] Alternatively, the pile extractor tip 1 may be integrally provided to the earth-penetrating member 20 by welding or the like. In this way, the entire integrated pile extractor 2 can be produced at relatively low cost.

[0052] Although the embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the illustrated embodiments. Various modifications and variations can be made to the illustrated embodiments within the same scope as the present invention or within an equivalent scope. [Explanation of symbols]

[0053] 1: Pile puller tip 2: Stake puller 3:Pile 4: Heavy machinery 10: Cylindrical wall 10a: Vertical shaft 10b: Storage section 10c: First receiving part 10d: Second receiving part 11: Excavation blade 11a: Outer blade part 11b: Inner blade part 12: Fall-off prevention claw 20: Underground penetration member 21: Cylindrical wall 21a: Opening 121 :Outer part 122:Inner part 123: Rib section 124: Rib section 201: Piping

Claims

1. A cylindrical pile extraction tip tool is located at the tip side of a cylindrical ground-penetrating member that is inserted into the ground, excavates the soil around a pile buried in the ground by rotating an excavation blade around the cylindrical axis of the ground-penetrating member, and, with the pile housed inside the ground-penetrating member, positions a fall-off prevention claw below the pile and pulls out the pile together with the ground-penetrating member, The fall-off prevention claw is rotatable around a vertical shaft portion provided on the cylindrical wall portion of the pile pulling tip tool, and has an outer portion located outside the cylindrical wall portion relative to the vertical shaft portion, and an inner portion located inside the cylindrical wall portion relative to the vertical shaft portion, During the rotation for the excavation, the outer portion receives resistance from the soil, and the fall-off prevention claw rotates in a direction in which the inner portion is positioned closer to the inner surface of the cylindrical wall portion. the outer portion receives resistance from the soil when the tool is rotated in the opposite direction to the rotation for the excavation when the pile is pulled out, causing the anti-fall-off claw to rotate in a direction in which the inner portion moves away from the cylindrical wall portion, and the inner portion is positioned below the pile.

2. 2. The pile pulling tip tool according to claim 1, wherein the digging blade has an outer cutting edge portion that protrudes outward beyond the outer peripheral surface of the cylindrical wall portion, and an end of the outer portion of the fall-off prevention claw is positioned beyond the outer end of the outer cutting edge of the digging blade.

3. 2. The pile pulling tip tool according to claim 1, wherein the excavation blade has an inner cutting edge portion that protrudes inward beyond the inner peripheral surface of the cylindrical wall portion, and an end of the inner portion of the fall-off prevention claw is positioned so as not to protrude beyond the inner cutting edge portion of the excavation blade during the excavation.

4. 2. The pile extracting tip tool according to claim 1, wherein an end of the outer portion of the anti-fall-off claw when extracting the pile is located farther from the outer surface of the cylindrical wall portion than an end of the outer portion when excavating the pile.

5. 2. The pile extractor tip according to claim 1, wherein a first receiving portion is located on an outer surface of the cylindrical wall portion to receive an end of the outer portion during the excavation.

6. 2. The pile extractor tip according to claim 1, wherein a second receiving portion is located on an outer surface of the cylindrical wall portion to receive an end of the outer portion when the pile is extracted.

7. 2. The pile extracting tip tool according to claim 1, wherein a surface of the inner portion of the fall-off prevention claw facing the pile forms an arc-shaped concave surface, and during the excavation, the arc-shaped concave surface forms a part of the inner curved surface of the cylindrical wall portion.

8. 2. The pile pulling tip according to claim 1, wherein the outer portion and the inner portion are connected by a rib portion.

9. 2. The pile extracting tip according to claim 1, wherein the pile extracting tip is detachable from the ground-penetrating member.

10. 2. The pile extractor tip according to claim 1, wherein said pile extractor tip is integrally provided with said ground-penetrating member.

11. 2. The pile extractor tip tool according to claim 1, wherein a housing section for housing the inner portion during the excavation is formed in the cylindrical wall section, and an outer peripheral surface section of the cylindrical wall section at the housing section and a portion in its vicinity protrudes outward more than other outer peripheral surface sections.

12. 2. The pile extracting tip tool according to claim 1, wherein a housing portion for housing the inner portion during the excavation is formed in the cylindrical wall portion, and the cylindrical wall portion has a thickness that can be formed without causing an outer peripheral surface portion of the cylindrical wall portion to protrude outward at a location where the housing portion is formed.

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