Pile extraction assisting device, pile extraction apparatus, and pile extraction method

Abstract

This invention provides a pile extraction aid and a pile extraction device that enable the efficient extraction of piles buried underground while suppressing costs and other factors, as well as a pile extraction method using these. [Solution] A pile extraction assist device for assisting a pile extraction device that extracts a pile buried in the ground by gripping the pile head with a first clamping piece and a second clamping piece, comprising a gripping pressure member joined to the first clamping piece which moves when gripping the pile head, and a gripping receiving member joined to the second clamping piece which is stationary when gripping the pile head, wherein the gripping pressure member is longer than the first clamping piece, and the gripping receiving member is cylindrical in shape with an opening on its side that is larger than or equal to the gripping pressure member and into which the first clamping piece can be inserted, and is joined to the second clamping piece such that the gripping pressure member is positioned inside the opening.

Description

Technical Field

[0001] The present invention relates to a pile pulling auxiliary tool for assisting a pile pulling device that pulls out a pile embedded underground, a pile pulling device provided with the pile pulling auxiliary tool, and a pile pulling method using the pile pulling device.

Background Art

[0002] Conventionally, at construction sites and the like, piles, which are rod-shaped structures, are sometimes driven into the ground to increase the strength of soft ground and prevent inclination, subsidence, and the like of buildings constructed thereon. Piles driven and embedded underground are often pulled out when demolishing a building constructed above them. While a new building may be constructed using existing piles, piles are treated as industrial waste when they are no longer needed, so it is desirable to pull them out when they are no longer used. Pile pulling work is carried out not only when demolishing buildings, but also when reusing land where embedded piles remain as existing piles.

[0003] There are various types of piles, including pine piles (wooden piles) processed from round pine logs, steel piles made of steel, and concrete piles made of concrete. Among these, pine piles have been used for a long time, and although they are less commonly used now compared to steel piles and concrete piles, many pine piles remain as existing piles, so pine pile pulling work is also necessary.

[0004] The methods used for extracting piles are broadly classified into three types: direct extraction, edge-cutting extraction, and crushing / removal. Direct extraction is a method of directly extracting piles using heavy machinery, and includes static extraction and vibro-hammer extraction. Edge-cutting extraction, also known as the casing method, is a method of inserting a cylindrical object called a casing into the ground around the pile, cutting the space between the pile and the ground, and then extracting the pile, and includes ring-throwing and chucking methods. Crushing / removal is a method of removing piles by cutting or crushing them into powder rather than extracting them, and includes all-casing crushing / removal methods. Each method has its advantages and disadvantages, and the appropriate method is selected considering the conditions of the work site, cost, and work period.

[0005] In the direct extraction method, the pile head is usually grasped with a wire or chuck and pulled out. A chuck is a claw-like mechanism for gripping the pile head. One type of direct extraction method, the vibro-hammer extraction method, uses vibration to extract piles. It uses a machine called a vibro-hammer that generates vibrations to reduce frictional resistance between the pile and the ground, making it easier to extract the pile. The direct extraction method has advantages such as minimizing the impact on the surrounding ground and shortening the construction period, as it suppresses drilling around the pile and extracts the pile directly. The vibro-hammer extraction method also has the advantage of being able to extract long piles. However, strong force is required to extract a pile directly, and even if frictional resistance is reduced by vibrating the pile, considerable force is still required. In particular, when extracting pine piles using the vibro-hammer extraction method, it may be difficult to firmly grasp the pile head if the pile head is corroded or otherwise damaged.

[0006] Solutions have been proposed to address the challenges encountered when using the vibro-hammer extraction method to remove piles such as pine piles.

[0007] For example, Japanese Utility Model Publication No. 56-206739 (Patent Document 1) proposes a pile extraction device used in an existing pile removal method for extracting and removing existing piles (support piles such as pine piles) remaining in the ground beneath a demolished existing building. The pile extraction device described in Patent Document 1 is a device consisting of a combination of a vibration exciter and a hydraulic chucking device, which extracts pine piles, etc., by sandwiching the pile head between a push plate that moves back and forth and the inner surface of a casing pipe.

[0008] Japanese Utility Model Publication No. 6-34046 (Patent Document 2) proposes a pile extraction device for extracting pine logs (pine piles), in which the pile is inserted between a semi-cylindrical part and a semi-cylindrical clamping member, and the outer circumference of the inserted pile is pressed against the clamping member by the clamping part to hold it in place. In the pile extraction device described in Patent Document 2, the pile near the top is inserted between the semi-cylindrical part and the clamping member, and is pressed against the inner surface of the semi-cylindrical part. Furthermore, after the shoe contacts the outer circumference of the pile inside the semi-cylindrical part, it is pressed against the inner surface of the clamping member, thereby holding the pile with an even stronger clamping force.

[0009] Japanese Utility Model Publication No. 56-8635 (Patent Document 3) proposes a pulling device that can grip the head of an existing wooden pile with roughly equal force on both sides using a hydraulic telescopic device. In the pulling device described in Patent Document 3, a structure composed of a connecting rod, an arm rod, and a clamping body is connected symmetrically to the telescopic device, thereby enabling the device to reliably grip the head of the wooden pile with roughly equal force on both sides. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Japanese Utility Model Publication No. 56-206739 [Patent Document 2] Japanese Utility Model Publication No. 6-34046 [Patent Document 3] Japanese Utility Model Publication No. 56-8635 [Overview of the project] [Problems that the invention aims to solve]

[0011] The vibro-hammer used in the vibro-hammer extraction method typically grips the pile head with a chuck mechanism resembling claws. In contrast, the pile extraction devices described in Patent Documents 1 and 2 employ a different structure to firmly grip the pile. Specifically, the pile extraction device described in Patent Document 1 grips the pile head with a casing pipe that is larger in diameter than the pile head and a push plate that can move back and forth, while the pile extraction device described in Patent Document 2 clamps the pile with a semi-cylindrical part and a clamping member, and further presses the pile against the inner surface of the clamping member with a shoe. Thus, the pile extraction devices described in Patent Documents 1 and 2 are manufactured with a structure different from that of a normal vibro-hammer, which may affect costs and other factors.

[0012] The extraction device described in Patent Document 3 grips the pile head with clamping bodies similar to those of a conventional vibro-hammer, but its structure is designed so that equal forces act on the left and right clamping bodies. This suggests that it may require a different manufacturing structure than a conventional vibro-hammer, and thus has the same problems as the pile extraction devices described in Patent Documents 1 and 2. Furthermore, it is unclear whether the structure of the clamping bodies in the extraction device described in Patent Document 3 can strongly grip the pile.

[0013] The present invention has been made in light of the circumstances described above, and the object of the present invention is to provide a pile extraction aid and a pile extraction device that enable the efficient extraction of piles buried in the ground while suppressing costs and other factors, as well as a pile extraction method using them. [Means for solving the problem]

[0014] The present invention relates to a pile extraction assist device for assisting a pile extraction device that extracts a pile by gripping the pile head of a pile buried in the ground with a first clamping piece and a second clamping piece, and the above object of the present invention is achieved by comprising a gripping pressure member joined to the first clamping piece which moves when gripping the pile head, and a gripping receiving member joined to the second clamping piece which is stationary when gripping the pile head, wherein the gripping pressure member is longer than the first clamping piece, and the gripping receiving member is cylindrical in shape with an opening on its side that is larger than or equal to the gripping pressure member and into which the first clamping piece can be inserted, and is joined to the second clamping piece such that the gripping pressure member is positioned inside the opening.

[0015] The above object of the present invention is more effectively achieved by the gripping receiving member having a closed shape in the circumferential direction at its lower end when gripping the pile head, or by the lower end of the gripping receiving member being thicker than other parts of the gripping receiving member, or by the gripping receiving member having a protective member on its inner surface located below the gripping pressure member when gripping the pile head, or by at least one of the gripping pressure member and the gripping receiving member having a circumferentially extending projection on the surface that contacts the pile when gripping the pile head.

[0016] Furthermore, the present invention relates to a pile extraction device, and the above-mentioned objective of the present invention is achieved by joining the above-mentioned pile extraction auxiliary device.

[0017] Furthermore, the present invention relates to a pile extraction method, and the above objective of the present invention is achieved by extracting the pile using the above pile extraction device, and is achieved more effectively by burying the lower part of the pile extraction aid in the ground when gripping the pile head. [Effects of the Invention]

[0018] According to the pile pulling auxiliary tool, pile pulling device and pile pulling method of the present invention, an existing pile pulling device such as a vibrohammer can be used, so that costs and the like can be suppressed. Further, since the pile is gripped by the gripping pressure member and the gripping receiving member, the pile can be firmly gripped, and efficient work can be performed. [Brief Description of Drawings]

[0019] [Figure 1] It is a perspective view showing an example (first embodiment) of the pile pulling auxiliary tool according to the present invention and a pile pulling device provided with the same. [Figure 2] It is an exploded perspective view showing an example (first embodiment) of the pile pulling device in a state where the pile pulling auxiliary tool is removed from the vibrohammer. [Figure 3] It is a view showing an example (first embodiment) of the gripping pressure member, FIG. 3(A) is a left side view, and FIG. 3(B) is a front view. [Figure 4] It is a view showing an example (first embodiment) of the gripping receiving member, FIG. 4(A) is a front view, and FIG. 4(B) is a right side view. [Figure 5] It is a front view showing another example (first embodiment) of the gripping receiving member. [Figure 6] It is an exploded perspective view showing an example (second embodiment) of the pile pulling device in a state where the pile pulling auxiliary tool is removed from the vibrohammer. [Figure 7] It is a view showing an example (second embodiment) of the gripping receiving member, FIG. 7(A) is a front view, and FIG. 7(B) is a right side view. [Mode for Carrying Out the Invention]

[0020] The pile extraction assist device according to the present invention is attached to a pile extraction device such as a vibro-hammer used when extracting piles buried in the ground by methods such as the vibro-hammer extraction method, and assists in the pile extraction work by the pile extraction device. A vibro-hammer has a structure in which the pile head is gripped with a chuck mechanism like a claw and the pile is extracted. The pile extraction assist device according to the present invention is used by joining it to the member of the chuck, which has a structure in which two members work together to grip the pile head. Normally, one of the members of the vibro-hammer chuck is movable, and the pile head is gripped by the movement of that member. The pile extraction assist device according to the present invention consists of a gripping pressure member that is joined to the member that moves when gripping the pile head (first gripping piece), and a gripping receiving member that is joined to the member that remains stationary when gripping the pile head (second gripping piece).

[0021] The gripping pressure member has a vertical length longer than the first clamping piece when gripping the pile head. The gripping receiving member has a vertical length greater than or equal to the length of the gripping pressure member when gripping the pile head, and is cylindrical with an opening on its side large enough to insert the first clamping piece. Here, cylindrical means a shape that is hollow inside like a cylinder, and the cross-section is not limited to a circle, but also includes shapes with polygonal cross-sections, etc. Furthermore, the opening may be a shape that extends to both ends in the axial direction of the gripping receiving member, a shape that extends to only one end, or a shape that does not extend to both ends.

[0022] The gripping receiving member is joined to the second clamping piece so that the gripping pressure member is positioned inside the opening. This allows the first clamping piece to be moved even when the gripping pressure member is joined.

[0023] By joining a gripping pressure member and a gripping receiving member of this shape to the first clamping piece and the second clamping piece respectively, inserting the pile head between the gripping pressure member and the gripping receiving member, and moving the first clamping piece to grip the pile head with the gripping pressure member and the gripping receiving member, the pile head can be gripped more firmly than when gripping with only the first clamping piece and the second clamping piece.

[0024] The pile extraction aid according to the present invention allows for the reinforcement of the lower end of the gripping receiving member, which is the end that is below when gripping the pile head. By reinforcing the lower end, it becomes easier to bury the lower part (lower portion) of the pile extraction aid in the ground when gripping the pile head, allowing the pile to be gripped at a deeper position. Even if the portion exposed above ground is short, it becomes possible to grip the pile over a longer area, resulting in a more secure grip. To reinforce the lower end, for example, the opening described above does not extend to the lower end, and the lower end can be made into a closed shape in the circumferential direction. By making it a closed shape, the lower end can be reinforced more effectively than if it were a partially open shape. Furthermore, the lower end can be reinforced by making its thickness (radial length) thicker than the thickness of other parts. Whether the lower end is a closed shape in the circumferential direction or a partially open shape, the thickness of the lower end can be increased.

[0025] The pile extraction aid according to the present invention can be provided with a protective member on the inner surface of the gripping receiving member to protect the gripping pressure member. The protective member is positioned below the gripping pressure member when gripping the pile head, and when the lower part of the pile extraction aid is buried in the ground, it can suppress damage such as the gripping pressure member coming into contact with the ground and breaking.

[0026] The pile extraction assisting tool according to the present invention can have circumferentially extending protrusions on the surfaces of the gripping pressure member and / or gripping receiving member that come into contact with the pile when gripping the pile head. By providing these protrusions, the pile can be gripped more firmly.

[0027] The present invention may be implemented as the pile extraction aid described above, as a pile extraction device to which the pile extraction aid is attached, or as a pile extraction method using the said pile extraction device to pull out the pile. In the pile extraction method, the lower part of the pile extraction aid can be buried in the ground to grip the pile head.

[0028] Embodiments of the present invention will be described below with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals, and their descriptions may be omitted. Furthermore, the numerical values ​​and shapes in the following description are illustrative, and the present invention is not limited to these.

[0029] Figures 1 to 4 show an example (first embodiment) of the pile extraction assist tool and pile extraction device equipped therewith according to the present invention. The pile extraction device 1 consists of a vibro-hammer 20 and a pile extraction assist tool 10 for extracting piles buried in the ground using methods such as the vibro-hammer extraction method. The pile extraction assist tool 10 consists of a gripping pressure member 11 and a gripping receiving member 12. Figure 1 is a perspective view of the pile extraction device 1, and Figure 2 is an exploded perspective view of the pile extraction device 1 with the pile extraction assist tool 10 removed from the vibro-hammer 20. Figure 3 is a diagram of the gripping pressure member 11 when it has been removed from the vibro-hammer 20, with Figure 3(A) being a left side view of the gripping pressure member 11 and Figure 3(B) being a front view of the gripping pressure member 11. Figure 4 is a diagram of the gripping receiving member 12 when it has been removed from the vibro-hammer 20, with Figure 4(A) being a front view of the gripping receiving member 12 and Figure 4(B) being a right side view of the gripping receiving member 12. Note that in Figures 1 and 2, some parts of the device are simplified or enlarged in size for ease of understanding. Also, in Figures 1 and 2, as indicated by the arrows, the top, bottom, right, and left sides are the "top," "bottom," "right," and "left" of the pile extraction device 1, respectively, and the front and rear sides are the "front" and "rear" of the pile extraction device 1, respectively. The same applies to Figure 6, which shows an example of the pile extraction device in the second embodiment.

[0030] A vibro-hammer is a device that applies vibration to piles, steel sheet piles, etc., to rapidly and temporarily reduce the resistance and frictional resistance at the tip, thereby enabling driving or extraction. A vibro-hammer typically includes a prime mover driven by an electric or hydraulic motor, a vibrator (vibration generator) that generates vibrations, a gripping device (chuck) that holds the pile or steel sheet pile, a damping device to prevent vibration force from being transmitted to the crane, and a control device to control its operation. The structure of the chuck varies depending on what is being gripped, and in this embodiment, the vibro-hammer 20 is equipped with a chuck 21 for gripping piles and steel pipes.

[0031] The chuck 21 grips the pile head of a pile buried in the ground and applies vibrations from the vibrator to the pile. To grip the pile head, the chuck 21 is equipped with gripping pieces 22 and 23 that are bent in a V-shape. The gripping pieces 22 and 23 are arranged on the body of the chuck 21 with their concave surfaces facing each other. The gripping piece 23 does not move, but the gripping piece 22 is movable in the left-right direction, and the movement of the gripping piece 22 grips the pile head.

[0032] The pile extraction assist device 10 consists of a gripping pressure member 11 and a gripping receiving member 12 that directly grip the pile head. The gripping pressure member 11 and the gripping receiving member 12 are joined to the clamping pieces 22 and 23 of the chuck 21, respectively. The gripping receiving member 12 is cylindrical in shape, and the gripping pressure member 11 is an arc shape which is part of the circumference of the cylinder. When the pile extraction device 1 pulls out a pile buried in the ground, it inserts the pile head into the gripping receiving member 12 and moves the gripping pressure member 11, which is joined to the movable clamping piece 22, toward the pile, thereby gripping the pile head with the gripping pressure member 11 and the gripping receiving member 12.

[0033] As described above, the gripping pressure member 11 is arc-shaped and sized to grip the pile more firmly than when the chuck 21 grips the pile with its gripping pieces 22 and 23. Specifically, the length of the gripping pressure member 11 (size in the front-to-back direction in Figure 2) is longer than the length of the gripping piece 22, for example, about 80 cm. The width of the gripping pressure member 11 (arc length) is greater than the width of the gripping piece 22, but is sized so as not to come into contact with the inner surface of the gripping receiving member 12 when gripping the pile, for example, about 30 cm. The thickness of the gripping pressure member 11 (size in the left-to-right direction in Figure 2) is approximately 1 cm, taking into consideration the strength required when gripping the pile.

[0034] The gripping pressure member 11 is joined to the clamping piece 22 by welding or the like, on the convex surface (the right surface in Figure 2), in such an orientation that the longitudinal direction of the gripping pressure member 11 (the front-to-back direction in Figure 2) is the same as the vertical direction when gripping the pile.

[0035] As described above, the gripping support member 12 is cylindrical, and the pile head is inserted into it. The recessed surface of the moving gripping pressure member 11 (the left surface in Figure 2, hereinafter referred to as the "recessed surface") and the inner surface of the gripping support member 12 grip the pile head. Therefore, the inner diameter of the gripping support member 12 is large enough to accommodate the insertion of the pile head, for example, about 40 cm. As the gripping support member 12 grips the pile head as described above, the length of the gripping support member 12 (the length in the front-to-back direction in Figure 2) is greater than or equal to the length of the gripping pressure member 11, and the length takes into account the protective member 13, which will be described later, being provided at the end, for example, about 100 cm.

[0036] The gripping receiving member 12 has an opening 16 on its side that is large enough to insert the clamping piece 22. The pile extraction device 1 grips the pile head inserted into the gripping receiving member 12 by moving the gripping pressure member 11 radially (left-right direction in Figure 1) of the gripping receiving member 12. At this time, the clamping piece 22 to which the gripping pressure member 11 is joined moves from the outside to the inside of the gripping receiving member 12, so an opening 16 is provided on the side of the gripping receiving member 12 to enable this movement. In the gripping receiving member 12, the opening 16 is provided in a shape that extends axially (front-back direction in Figure 2) from the upper end, which is the upper end when gripping the pile head, and has a rectangular shape with a length (axial size) and width (circumferential size) that can insert the clamping piece 22, for example, a rectangle with a length of about 50 cm and a width of about 30 cm. The gripping receiving member 12 is joined to the clamping piece 23 such that the gripping pressure member 11 is located inside the opening 16 (to the left of the opening 16 in Figure 2).

[0037] The pile extraction device 1 embeds the lower end 15 of the gripping receiving member 12 into the ground so that the pile can be gripped at a deeper position when inserting the pile head of a pile buried in the ground into the gripping receiving member 12. To facilitate embedding into the ground, the lower end 15 of the gripping receiving member 12 is circular in shape, which is closed in the circumferential direction, and furthermore, the thickness (radial size) of the lower end 15 is greater than that of other parts. For example, the thickness of the parts other than the lower end 15 is the same as that of the gripping pressure member 11 (for example, about 1 cm), but the thickness of the lower end 15 is greater (for example, about 2 cm). The length of the increased thickness, that is, the length (axial size) of the lower end 15, is set considering strength, weight, etc., and is for example, about 1 cm. However, if the gripping receiving member 12 is made of a high-strength material, and it is not necessary to make the thickness of the lower end 15 greater than that of other parts, the entire gripping receiving member 12 may be made of the same thickness.

[0038] When embedding the lower end 15 of the gripping support member 12 into the ground, the gripping pressure member 12 is provided with a protective member 13 on its inner surface to protect the gripping pressure member 11 located near the inner surface of the gripping support member 12. To prevent the gripping pressure member 11 from contacting the ground, the protective member 13 is provided near the lower end 15 at a position below the gripping pressure member 11 when gripping the pile head. The protective member 13 is arc-shaped, similar to the gripping support member 12, and its width (arc length) is approximately the same as that of the gripping pressure member 11 (for example, about 30 cm). The thickness of the protective member 13 (size in the left-right direction in Figure 2) is the thickness of the gripping pressure member 11 plus the height of the protruding portion 14a described later (for example, 2-3 cm), and the length of the protective member 13 (size in the front-back direction in Figure 2) is a size that takes strength and other factors into consideration (for example, about 2 cm).

[0039] On its outer surface, the gripping receiving member 12 is joined to the clamping piece 23 by welding or the like, so that the gripping pressure member 11 is positioned inside the opening 16 as described above.

[0040] The gripping pressure member 11 and the gripping receiving member 12 are provided with circumferentially extending protrusions 14 on the surfaces that come into contact with the pile when gripping, so that the pile head inserted into the gripping receiving member 12 can be gripped more firmly. The gripping pressure member 11 has multiple protrusions 14a on its concave surface, and the gripping receiving member 12 has multiple protrusions 14b on its inner surface at least at positions facing the concave surface of the gripping pressure member 11. The size and / or number of protrusions 14a and 14b may be the same or different. For example, as shown in Figure 3(A), the gripping pressure member 11 has five protrusions 14a projecting at equal intervals. The length (circumferential size) of the protrusions 14a is approximately the same as the width of the gripping pressure member 11 (for example, about 30 cm), and the height (radial size) and thickness (axial size) of the protrusions 14a are set to a size that takes into account the strength required when gripping a pile (for example, 1-2 cm and 2 cm, respectively). The gripping receiving member 12 has more protrusions 14b projecting at equal intervals than the protrusions 14a (for example, seven). The length of the protrusions 14b is approximately the same as the protrusions 14a (for example, about 30 cm), and the height and thickness of the protrusions 14b are smaller than those of the protrusions 14a (for example, both about 1 cm).

[0041] The pile extraction assist tool 10 is made of a material that takes into consideration strength, hardness, durability, etc., and is made of steel such as carbon steel, stainless steel, or alloy steel. However, the pile extraction assist tool 10 may be made of a material other than steel, the materials used for the gripping pressure member 11 and the gripping receiving member 12 may be changed, and the protective member 13, etc. may also be made of different materials.

[0042] This section describes a method for extracting piles buried in the ground using a pile extraction device 1 configured in this manner. It is assumed that the pile extraction device 1 is connected to a lifting device such as a crane.

[0043] First, the ground is excavated using a hydraulic excavator or the like to expose the pile heads of the piles buried underground. In this case, the longer the pile head is exposed, the easier it is to grip, but in order to expose the pile head for a long time, it is necessary to excavate a wide area of ​​ground, and in the case of work in a small area such as a residential area, it can be difficult to excavate a wide area. In this embodiment, the pile extraction device 1 can bury the lower part of the pile extraction auxiliary tool 10 in the ground, so the pile can be efficiently extracted without exposing the pile head for a long time.

[0044] Once the pile head is exposed, the pile extraction device 1 is moved above the pile head using the lifting device, and the pile extraction device 1 is lowered so that the pile head is inserted into the gripping receiving member 12 from the lower end 15 of the gripping receiving member 12. Then, when the lower end 15 contacts the excavated surface, the pile extraction device 1 is lowered further while the vibrator of the vibro hammer 20 vibrates the chuck 21 and then the pile extraction auxiliary tool 10, burying the lower part of the pile extraction auxiliary tool 10 into the ground from the lower end 15. In this case, since it is protected by the protective member 13, it is acceptable for the lower part of the gripping pressure member 11 to be buried in the ground.

[0045] Once the pile extraction device 1 is embedded in the ground to an appropriate position, the gripping pressure member 11 is moved toward the pile, and the pile head is gripped by the gripping pressure member 11 and the gripping receiving member 12. Then, similar to a normal vibro-hammer, the pile extraction device 1 is raised by the lifting device while the chuck 21 and the pile extraction assist tool 10 are vibrated by the vibrator until the entire pile is exposed from the ground.

[0046] Finally, with the pile being held by the pile extraction device 1, the pile is moved to a safe location using the lifting device. Then, the gripping pressure member 11 is moved in the opposite direction to when it was being gripped, and the pile is released from the pile extraction device 1.

[0047] In this embodiment, the gripping receiving member 12 is cylindrical, but the gripping receiving member 12 may be of other shapes, such as a rectangular prism, as long as a pile can be inserted inside it. In this case, the gripping pressure member 11 may be shaped to match the shape of the gripping receiving member 12, or it may remain in an arc shape, as long as it can grip the pile head together with the gripping receiving member 12.

[0048] The opening 16 does not have to be rectangular in shape, as long as the gripping piece 22 can be inserted into it, and does not have to be open at the upper end of the gripping receiving member 12.

[0049] The shape of the protective member 13 does not have to be an arc shape, but can be any shape as long as it can protect the gripping pressure member 11. For example, it can be a shape composed of multiple members, as shown in Figure 5. Figure 5 is a front view of the gripping receiving member 17 when it has been removed from the vibro hammer 20, similar to Figure 4(A). The protective member 18 provided on the inner surface of the gripping receiving member 17 has a shape in which the protective member 13 is divided into multiple parts in the circumferential direction, and four of the divided members are arranged at equal intervals in the circumferential direction.

[0050] The protective member 13 may be omitted if the gripping pressure member 11 is made robustly and does not require protection. If the protective member 13 is not provided, the length of the gripping pressure member 11 and the length of the gripping receiving member 12 may be the same. The protruding portion 14 may also be omitted if the pile head can be firmly gripped without the protruding portion 14.

[0051] A second embodiment of the present invention will now be described. In the gripping receiving member 12 of the pile extraction assisting tool 10 in the first embodiment, the opening 16 does not extend to the lower end, and the lower end 15 has a closed shape in the circumferential direction. However, it is also possible for the opening to extend to the lower end, and for the lower end to have an open shape in the circumferential direction.

[0052] Figures 6 and 7 show an example of a pile extraction device (second embodiment) in which the gripping and receiving member has the shape described above. The pile extraction device 2 consists of a vibro hammer 20 and a pile extraction assist tool 30, and the pile extraction assist tool 30 consists of a gripping pressure member 31 and a gripping and receiving member 32. Figure 6 is an exploded perspective view of the pile extraction device 2 with the pile extraction assist tool 30 removed from the vibro hammer 20, similar to Figure 2. Figure 7 is a view of the gripping and receiving member 32 with the gripping and receiving member 32 removed from the vibro hammer 20, similar to Figure 4, where Figure 7(A) is a front view of the gripping and receiving member 32 and Figure 7(B) is a right side view of the gripping and receiving member 32.

[0053] The gripping member 32 is cylindrical, similar to the gripping member 12, but the opening 36 provided on its side to allow insertion of the clamping piece 22 extends axially from the upper end to the lower end, and the lower end is shaped so that the opening 36 is open in the circumferential direction. The inner diameter of the gripping member 32 is the same size as that of the gripping member 12 (for example, about 40 cm). Since the gripping member 32 is not provided with a protective member to protect the gripping pressure member 31, the length of the gripping member 32 may be shorter than that of the gripping member 12 by the amount of the protective member (for example, about 95 cm), or it may be the same length as the gripping member 12 (for example, about 100 cm). The length of the opening 36 is the same as that of the gripping member 32, and the width of the opening 36 may be the same as or different from that of the opening 16, as long as the clamping piece 22 can be inserted. Furthermore, the opening 36 does not have to be rectangular in shape, as long as the gripping piece 22 can be inserted into it, and it does not have to be open at the upper end of the gripping receiving member 32.

[0054] Unlike the gripping support member 12, the gripping support member 32 does not have a thicker lower end than the rest of the member, and has the same thickness throughout. Similar to the gripping support member 12, the lower end of the gripping support member 32 is embedded in the ground when gripping the pile head, so the thickness of the gripping support member 32 is such that the lower end can be embedded in the ground. However, since the weight increases with thickness, the thickness (for example, about 1.5 cm) is also taken into consideration. Alternatively, the gripping support member 32 may be made from a high-strength material to have the same thickness as the gripping support member 12, or its lower end may be made thicker than the rest of the member, as is the case with the gripping support member 12.

[0055] Similar to the gripping member 12, the inner surface of the gripping member 32 is provided with multiple circumferentially extending protrusions 34b to allow for a more secure grip on the pile head inserted into the gripping member 32. The size and / or number of the protrusions 34b may be the same as or different from the protrusions 14b provided on the gripping member 12.

[0056] The gripping pressure member 31 may have the same shape as the gripping pressure member 11, but it may also be longer than the gripping pressure member 11 to match the length of the opening 36. Furthermore, since the gripping receiving member 32 does not have a protective member, it is preferable that the thickness of the gripping pressure member 31 be the same as that of the gripping receiving member 32 so that it can withstand being buried in the ground.

[0057] In the embodiments described above (first and second embodiments), the pile extraction assist device is joined to the chuck 21 of the vibro-hammer 20. However, the pile extraction assist device according to the present invention can be applied to pile extraction devices other than vibro-hammers, as long as they can grip the pile head. However, a device that has a function to facilitate embedding into the ground, such as vibrating the pile extraction assist device like a vibro-hammer, is preferred, so that the lower part of the pile extraction assist device can be embedded in the ground when gripping the pile head.

[0058] The present invention can be realized not only as a pile extraction aid in the above-described embodiment, but also as a pile extraction device equipped with a pile extraction aid, or as a pile extraction method using said pile extraction device.

[0059] Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the invention. Furthermore, matters not explicitly disclosed in the above embodiments, such as the weight of the pile extraction aid, do not deviate from the range that a person skilled in the art would normally practice, and a value that a person skilled in the art could easily anticipate can be adopted. [Explanation of symbols]

[0060] 1, 2 Pile extraction device 10, 30 Stake removal aid 11, 31 Gripping pressure member 12, 17, 32 Grip receiving member 13, 18 Protective components 14, 14a, 14b, 34b protrusion 15 Lower end 16, 36 openings 20 Vibro-hammer 21 Chuck 22, 23 Clamping piece

Claims

1. A pile extraction assist device that assists a pile extraction device in which the pile head of a pile buried in the ground is gripped by a first gripping piece and a second gripping piece to pull out the said pile, A gripping pressure member is joined to the first clamping piece, which moves when the pile head is clamped, The system includes a gripping receiving member that is joined to the second clamping piece, which is stationary when the pile head is clamped, The gripping pressure member has a length exceeding that of the first clamping piece. The pile extraction aid is characterized in that the gripping receiving member is cylindrical in shape, having a length greater than or equal to the gripping pressure member, and having an opening on its side that is large enough to insert the first clamping piece, and is joined to the second clamping piece such that the gripping pressure member is positioned inside the opening.

2. The pile extraction aid according to claim 1, wherein the gripping receiving member has a closed shape in the circumferential direction at its lower end when gripping the pile head.

3. The pile extraction aid according to claim 2, wherein the lower end of the gripping support member is thicker than the other parts of the gripping support member.

4. The pile extraction aid according to claim 2, wherein a protective member is provided on the inner surface of the gripping receiving member, which is located below the gripping pressure member when gripping the pile head.

5. The pile extraction aid according to claim 1, wherein at least one of the gripping pressure member and the gripping receiving member has a circumferentially extending projection on the surface that contacts the pile when gripping the pile head.

6. A pile extraction device characterized by having a pile extraction assist tool according to any one of claims 1 to 5 attached to it.

7. A pile extraction method characterized by extracting the pile using the pile extraction device described in claim 6.

8. The pile extraction method according to claim 7, wherein the lower part of the pile extraction assisting device is buried in the ground when gripping the pile head.

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