JP2009046876A - Drawing device for existing pile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify and miniaturize a structure for projecting and retracting a holding claw from and into a casing. <P>SOLUTION: This drawing device for an existing pile comprises the casing 2 having an excavating blade at the bottom end, a casing rotatingly driving device for rotatingly driving the casing, and the holding claw 4 so installed as to project from and retract into the casing. The casing 2 has a window hole part 71 extending therethrough at the position where the holding claw 4 is installed. The holding claw 4 reciprocates between an engagement position where a shaft support part 4C is pivoted on a support shaft 8 on the inner side of the window hole part 71 as to be freely rotatable in a horizontal plane and an end part 4A projects into the casing 2 and is engaged with the bottom end of the existing pile P and a retreated position where the holding claw is retreated into a claw storage part 70 and not engaged with the bottom end of the existing pile P. The lengths and rotating angle ranges θ of the front end part 4A and the rear end part 4B of the holding claw 4 are so set that the projecting part 4D is kept projecting from the outer peripheral surface of the casing 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an existing pile pulling device used for removing an existing pile buried in the ground when rebuilding a building structure or the like.

  For example, in a building structure such as a building, a condominium, and a factory, piles are embedded up to a hard ground in the ground to support the load. When rebuilding these building structures, after dismantling and removing the old building, it is necessary to pull out the old existing piles deeply buried in the ground. Conventionally, as a method of removing unnecessary piles buried in the ground, an existing installation is performed while excavating around the existing piles in the ground by a rotating casing that is rotated by an auger machine that moves up and down along the leader of the vehicle. After excavating near the upper end of the pile, the existing pile was pulled out from the ground by binding a wire to the peripheral surface of the upper end of the pile and pulling it up with a crane.

  However, in the method as described above, it is necessary to pull up the casing after excavation by the casing and bind the wire to the upper end of the existing pile so as not to come off, so that the work takes a lot of labor and time. In addition, since the wire is tied to the upper end of the existing pile and pulled up, the pile may be cut off halfway during the pulling up, and it is not easy to pull out the pile that has been cut and left in the ground, The task is extremely difficult.

  Therefore, in recent years, similar to the conventional method described above, after excavating the periphery of an existing pile in the ground with a casing and cutting the edge between the existing pile and the ground, a plurality of gripping claws provided at the lower portion of the casing are removed. An existing pile pulling device has been proposed in which a lower end portion of an existing pile is gripped by projecting into the casing, and the existing pile is pulled out from the ground together with the casing by the upward movement of the auger machine by the winch. In this type of existing pile pulling device, there has been proposed one in which a hydraulic cylinder is used to cause the gripping claws to move in and out of the casing (see, for example, Patent Document 1).

Japanese Patent No. 3052135

  In an existing pile pulling device described in Patent Document 1, a hydraulic cylinder is attached to an upper end portion of a casing, and a gripping claw is connected to a piston rod of the hydraulic cylinder via a connecting rod. The gripping claw is provided at the lower part of the casing so as to be able to move up and down.When the piston rod of the hydraulic cylinder is extended and the connecting rod is moved downward, the gripping claw will fall down and its tip protrudes into the casing. Then, a transition is made to a gripping state in which the lower end of the existing pile is gripped. On the other hand, when the piston rod of the hydraulic cylinder is contracted and the connecting rod is moved upward, the gripping claw erects so that its tip is retracted from the inside of the casing, and the lower end of the existing pile is not gripped from the gripped state. Transition to the gripping state.

  However, in the existing pile pulling device having the above-described configuration, in order to move the plurality of gripping claws into and out of the casing, it is necessary to attach a plurality of hydraulic cylinders around the upper portion of the casing as a driving device. There is a problem that it becomes expensive and large. In particular, when the entire apparatus becomes large, the weight of the apparatus is increased, the excavation speed by the casing is lowered, and the mobility of the apparatus is also deteriorated, so that the efficiency of pulling out the existing pile is lowered. Furthermore, when the casing is pushed into the ground, the hydraulic cylinder and the connecting rod are also pushed into the ground together with the casing, so that the hydraulic cylinder and the connecting rod constituting the device are easily damaged due to the resistance of earth and sand. There is also.

  The present invention has been made paying attention to the above-described problems, and does not require a driving device such as a hydraulic cylinder in the configuration for moving the gripping claw in and out of the casing. An object of the present invention is to provide an existing pile pulling device that realizes the structure.

  A pulling device for an existing pile according to the present invention has a cylindrical casing that is pushed into the ground so as to surround the existing pile with a drilling blade for digging around the existing pile buried in the ground, A rotary drive device capable of rotating the casing around its central axis in forward and reverse directions, and a projecting part that protrudes into the casing at the lower part of the casing and engages with the lower end of the existing pile. It is provided with at least one gripping claw that can be provided. The casing has a window hole portion for projecting the gripping claws in and out at a position where the gripping claws are provided. The gripping claws are pivotally supported by the casing in the longitudinal direction so that they can freely rotate in a horizontal plane, and a portion ahead of the pivotal support projects into the casing and engages the lower end of the existing pile. Reciprocating between the angular position where it can be engaged and the angular position where it does not engage with the lower end of the existing pile, and the portion behind the shaft support portion remains protruding from the outer peripheral surface of the casing. The lengths of the front and rear portions and the rotation angle range are set.

  The existing pile pulling apparatus according to the present invention excavates the periphery of the existing pile with the excavating blade while rotating the casing by the rotation driving device. When the casing is rotated in the forward or reverse direction around its central axis in the ground, the gripping claws project from the outer peripheral surface of the casing to receive the resistance of earth and sand, so that the gripping claws are supported in the horizontal plane with the pivotal support as a fulcrum. To rotate in the forward or reverse direction. The portion of the gripping claw that is beyond the pivotal support portion protrudes into the casing and engages with the lower end of the existing pile and is not engaged with the lower end of the existing pile. It rotates between an angular position (hereinafter referred to as “retracted position”).

  In order to pull out the existing pile buried in the ground by the existing pile pulling device having the above-described configuration, the casing is moved in a predetermined direction so that the portion ahead of the shaft support portion of the gripping claw is localized at the retracted position. Push into the ground while rotating. When the lower end of the casing reaches a little lower than the lower end of the existing pile, when the casing is rotated in the direction opposite to that when the casing is pushed in, the gripping claw rotates in the opposite direction and the portion beyond the shaft support part is Move to the matching position. In this state, when the casing is pulled up, the portion of the gripping claw that is ahead of the shaft support portion engages with the lower end of the existing pile, and the existing pile is gripped by the gripping claw. By continuously pulling up the casing while holding the existing pile, the existing pile can be pulled out from the ground while being accommodated in the casing.

  According to the existing pile pulling device having the above-described configuration, the gripping claw rotates in the forward / reverse direction by rotating the casing in the forward / reverse direction in the ground, and the portion beyond the axial support portion is in the casing. Since the projecting operation is performed, it is not necessary to provide the casing with a drive device such as a hydraulic cylinder for causing the gripping claw to move in and out of the casing, and the configuration of the entire apparatus can be simplified and made compact. The apparatus is not damaged like the conventional existing pulling apparatus for pushing in.

In a preferred embodiment of the present invention, on the inner surface of the casing, when the portion ahead of the shaft support portion of the grip claw is at an angular position where it does not engage with the lower end of the existing pile, the shaft support portion ahead of the grip claw shaft portion is provided. A claw receiving portion into which the portions can be fitted is recessed.
According to this embodiment, when the portion of the gripping claw beyond the shaft support portion is in the retracted position where it does not engage with the lower end of the existing pile, the portion of the gripping claw is accommodated in the casing. There is no possibility that the part ahead of the branch protrudes, and there is no possibility that the gripping claws may come into contact with the existing pile when the casing is pushed into the ground.

  In a preferred embodiment of the present invention, the gripping claw is pivotally supported so as to be able to be displaced in the vertical direction within the window hole, and between the lower surface of the gripping claw and the lower opening edge of the window hole. Is capable of restricting the rotation of the gripping claws by engaging with each other when the portion ahead of the shaft support portion of the gripping claws protrudes into the casing and is in an angular position where it can be engaged with the lower end of the existing pile. A detent mechanism is provided.

  According to this embodiment, when the portion ahead of the shaft support portion of the gripping claw is located at the engagement position at which the lower end of the existing pile can be engaged, the gripping claw is moved horizontally by the action of the detent mechanism. Since the rotation is completely restricted, the portion of the grip claw beyond the shaft support portion is not displaced in the direction in which the engagement is disengaged from the engagement position.

  According to the present invention, the gripping claws are rotated by rotating the casing in the forward and reverse directions in the ground, and the portion ahead of the shaft support portion can be moved into and out of the casing. In order to cause the gripping claw to move in and out of the casing as in the pulling device, it is not necessary to provide a driving device such as a hydraulic cylinder, and the configuration of the entire device can be simplified and made compact.

1 and 2 show the overall configuration of an existing pile drawing device 1 (hereinafter referred to as “pile drawing device”) according to an embodiment of the present invention.
The pile pulling device 1 of the present invention is used to remove an existing pile buried in the ground when rebuilding a building structure, and the surroundings of the existing pile buried in the ground A casing 2 for cutting the edge between the existing pile and the ground, a casing rotation drive device 3 for rotationally driving the casing 2, and a lower portion of the casing 2 that protrudes into the casing 2 and protrudes into the casing 2 Two grip claws 4 for gripping the lower end are provided.

The casing rotation drive device 3 has a motor (not shown) that generates a rotational force for rotating the casing 2 inside, and an annular rotation drive shaft 30 that is rotated by the motor projects from the lower portion. Yes. A connecting portion 31 is integrally provided at a lower portion of the rotation drive shaft 30, and an upper end portion of the casing 2 is connected to the connecting portion 31 so as to be integrally rotatable.
In FIG. 1, reference numeral 10 denotes a crane vehicle that suspends the pile pulling device 1 in the vertical direction, and engages a hook 32 attached to the upper portion of the casing rotation driving device 3 with a hook 11 attached to the crane vehicle 10. Then, the pile pulling apparatus 1 is suspended in a vertical posture and is lifted and lowered in the vertical direction. Reference numeral 12 denotes a steady rest plate for preventing the casing 2 from precessing while excavating the ground.

  The casing 2 is formed of a hollow cylindrical body having a lower end having an inner diameter larger than the outer diameter of the existing pile, and is formed of, for example, a steel pipe. On the upper surface of the casing 2, there is provided a joint portion 20 that can be connected to the connecting portion 31 of the casing rotation drive device 3, and the vertical movement caused by the rotation of the rotary drive shaft 30 and the undulation of the crane 10 is casing through the joint portion 20. 2 can be transmitted.

  A plurality of openings 21 having a predetermined size are formed on the circumferential surface of the casing 2 over the entire length of the casing 2. The state of the existing pile inserted into the casing 2 through the opening 21 can be visually observed. The opening 21 is also used for discharging earth and sand or water to the outside of the casing 2. Furthermore, by providing this opening 21, the weight of the casing 2 can be reduced.

  At the lower end of the casing 2, a head portion 5 made of a cylindrical body having an inner diameter that coincides with the casing 2 and has an outer diameter and a wall thickness larger than those of the casing 2 is integrally provided by welding. On the outer peripheral surface of the lower end portion of the head portion 5, as shown in FIGS. 2 and 3, 18 excavation blades 6 for scraping and digging the ground around the existing pile P are provided from the lower end portion of the head portion 5. It is attached at an equal angle so as to protrude. The excavation blade 6 has a blade body such as a cemented carbide chip or diamond, and is firmly fixed to the lower end portion of the head portion 5 by welding or bolt tightening. In addition, you may change the number and attachment position of the excavation blade 6 to an optimal thing suitably according to use conditions.

  As shown in FIGS. 2 and 5, the head portion 5 is provided with two claw accommodating spaces 7 formed by cutting off a part of the peripheral wall of the head portion 5 at diagonal positions. Each nail accommodating space 7 is a concave nail having a depth and a circumferential length matching the thickness and length of a portion (hereinafter referred to as a “tip portion”) 4A beyond a shaft support portion 4C of the gripping nail 4 to be described later. The housing portion 70 and a window hole portion 71 that penetrates the peripheral wall of the head portion 5 continuous with the claw housing portion 70 inward and outward. The vertical height of the nail receiving space 7 is sufficiently larger than the vertical height w of the gripping claws 4 so that the gripping claws 4 can be moved up and down (in this embodiment, the height of the gripping nails 4). (a height corresponding to approximately twice w). In each claw receiving space 7, the gripping claw 4 has an angular position (hereinafter referred to as “engagement”) where the tip end 4 </ b> A protrudes into the casing 2 and can be engaged with the outer peripheral surface of the lower end of the existing pile P. The position is referred to as “position” (see FIG. 5), and the angular position where the retraction from the inside of the casing 2 into the claw accommodating portion 70 and does not engage with the lower end of the existing pile P (hereinafter referred to as “retraction position”; see FIG. 4). It is supported to freely rotate so that it can reciprocate over a rotation angle range θ between them.

  The head portion 5 is not necessarily formed integrally with the casing 2, and may be configured to be detachably attached to the lower end portion of the casing 2. With such a configuration, when the head portion 5 is consumed due to the excavation blade 6 or the gripping claws 4 being damaged or damaged by pushing the casing 2 into the ground or pulling out the existing pile P, other The head portion 5 can be easily replaced.

  Each of the gripping claws 4 is formed of, for example, a steel material, and has a shape in which the distal end portion 4A is slightly curved as shown in FIGS. When the gripping claw 4 rotates and its tip part 4A protrudes most into the casing 2, the tip edge of the tip part 4A reaches a position beyond the center of the casing 2 (head part 5). A small space E that surrounds the center of the casing 2 (head portion 5) is formed by the tip portion 4A of the front end, and the lower end of the existing pile P is received. Each gripping claw 4 has an intermediate portion in the length direction that is pivotally supported by the support shaft 8 in the window hole portion 71 (hereinafter, the intermediate portion is referred to as “shaft support portion 4 </ b> C”). The support shaft 8 is provided vertically in the window hole portion 71, and both end portions thereof are pivotally fixed to through holes 72 and fitting holes 73 provided at the upper and lower edges of the window hole portion 71, respectively. Each gripping claw 4 can freely rotate in a horizontal plane with the support shaft 8 (shaft support portion 4C) as a fulcrum, and its tip end portion 4A can move in and out of the casing 2. Each gripping claw 4 is slidably supported by the support shaft 8 and can be displaced in the vertical direction along the support shaft 8 in the window hole 71.

  Each gripping claw 4 is formed in such a length that a portion (hereinafter referred to as “rear end portion 4 </ b> B”) behind the shaft support portion 4 </ b> C protrudes from the outer peripheral surface of the head portion 5 through the window hole portion 71. The rear end portion 4B is maintained in a state in which a part (hereinafter referred to as “protruding portion”) 4D protrudes out of the head portion 5 over the rotation angle range θ of the gripping claw 4. The gripping claw 4 is rotated only by rotating the 2 in the forward and reverse directions in the ground, and the tip portion 4 </ b> A can be projected and retracted with respect to the inside of the casing 2.

4 and 5, when the casing 2 is pushed into the ground while rotating in the x direction shown in FIG. 4, the protrusion 4 </ b> D protrudes out of the casing 2 at the rear end 4 </ b> B of the gripping claw 4. As a result of the resistance of earth and sand, a strong pressing force N acts on the gripping claws 4. As a result, the gripping claw 4 rotates around the support shaft 8 in the direction r shown in FIG. Match.
When the casing 2 is thus pushed into the ground while rotating, as shown in FIG. 6, the gripping claws 4 have a window hole portion along the support shaft 8 in order to receive the resistance T of earth and sand from the lower side to the protruding portion 4D. The inside of 71 will be displaced upwards and it will be hold | maintained in the state which floated in the window hole part 71. FIG.

  On the other hand, when the casing 2 is rotated in the y direction shown in FIG. 5 when the distal end portion 4A of the gripping claw 4 is in the above-described retracted position, the protruding portion 4D protruding outside the casing 2 receives earth and sand resistance. Thus, a strong pressing force Q in the opposite direction to the above acts on the gripping claws 4. As a result, the gripping claws 4 rotate around the support shaft 8 in the s direction shown in FIG. 5, and their tip portions 4 </ b> A protrude from the claw storage portion 70 to the casing 2 portion to the outer peripheral surface of the lower end of the existing pile P. It moves to the engaging position to engage. In this embodiment, when the gripping claw 4 rotates and its front end portion 4A shifts to the engagement position, the rear end portion 4B of the gripping claw 4 abuts against the opening side edge of the window hole portion 71, so that the transition is made. Is forcibly stopped for positioning.

  In addition, in this Example, although the front-end | tip part 4A of each holding nail | claw 4 is formed in the slightly curved shape so that a planar shape may correspond to the convex surface of the outer peripheral surface of the lower end of the existing pile P, it is embed | buried. Depending on the shape of the existing pile P, it is also possible to form various shapes, for example, a rectangular shape.

  Further, in this embodiment, each gripping claw 4 is pivotally supported by the support shaft 8 in the window hole portion 71 in the longitudinal direction, but is not limited thereto. For example, the support shaft 8 is vertically installed on the outer peripheral surface of the casing 2 by welding or the like, and each gripping claw 4 is configured such that an intermediate portion in the length direction is supported by the support shaft 8 outside the casing 2. Also good.

  In the pile drawing device 1 of this embodiment, in addition to the above-described configuration, the tip 4A of the gripping claw 4 is engaged with the lower end of the existing pile P between the gripping claw 4 and the opening lower edge of the window hole 71. An anti-rotation mechanism 9 is provided that can restrict the rotation of the gripping claws 4 when in the mating engagement position (see FIG. 5).

  As shown in FIGS. 4 to 9, the anti-rotation mechanism 9 of this embodiment is provided on a plurality of protrusions 90 provided on the lower edge of the opening of the window hole 71 and on the lower surface of the gripping claw 4. And a plurality of engaging grooves 91. Each of the protrusions 90 has a predetermined length, and is projected at equal intervals on the lower edge of the opening of the window hole portion 71. These protrusions 90 are arranged so that the gripping claws 4 are opposed to the respective engagement grooves 91 when they are located at an engagement position (see FIGS. 5 and 7) where the lower end of the existing pile P is engaged. The installation position is determined.

  Each of the engaging grooves 91 is formed on the lower surface of the gripping claw 4 in a shape and size that matches the outer shape of the protrusion 90, and the arrangement interval thereof is matched to the arrangement interval of the protrusions 90. Each protrusion 90 and each engagement groove 91 are not limited to the shape described above, and for example, each protrusion 90 may be formed in a hemispherical shape, and each engagement groove 91 may be formed in a circular depression.

  According to the anti-rotation mechanism 9 having the above-described configuration, when the gripping claws 4 are positioned at the engagement position where the gripping claws 4 are engaged with the lower ends of the existing piles P, the engagement grooves 91 and the protrusions 90 are engaged with each other. Then, the rotation of the gripping claws 4 in the horizontal direction is completely restricted. Therefore, once the distal end portion 4A of the gripping claw 4 is positioned at the engagement position, the engagement with the existing pile P is not released by the rotation of the gripping claw 4.

  In addition, although not shown in figure, in this pile drawing-out apparatus 1, the jet pipe for making water and air jet into the inside of the casing 2 is piped by the up-down direction, and the front-end | tip of these jet pipes is a casing. It faces the lower end of 2.

Next, the extraction operation | work of the existing pile P by the pile extraction apparatus 1 of an above-described structure is demonstrated in detail.
First, the upper end portion of the existing pile P to be removed is slightly exposed on the ground surface, and the steady plate 12 shown in FIG. 1 is installed so that the opening 12a is positioned around the existing pile P, and firmly attached to the ground surface. Fix it. Next, the pile pulling device 1 is suspended by the crane vehicle 10 so that the casing 2 of the pile pulling device 1 enters the opening 12a of the steady plate 12 and the upper end of the existing pile P enters the casing 2. The pile drawing device 1 is positioned in the position.

  Next, the casing 2 is rotated while rotating the casing 2 in the x direction shown in FIG. 4 by the casing rotation driving device 3 and excavating the soil around the existing pile P with the excavating blade 6 fixed to the lower end portion of the head portion 5. Gradually lower and push into the ground. At this time, the tip end portion A of each gripping claw 4 is retracted from the inside of the casing 2 and fitted into the claw accommodating portion 70 when the protruding portion 4B receives the resistance of earth and sand. Further, each gripping claw 4 receives the resistance of earth and sand from below through the protrusion 4 </ b> D and is displaced upward along the support shaft 8. Then, when the lower end (head part 5) of the casing 2 reaches a little lower than the lower end of the existing pile P (FIG. 6), the rotation of the casing 2 is stopped.

  In addition, when pushing the casing 2 into the ground, water is ejected from the lower end of the casing 2 by the ejection pipe, and the sediment around the lower end of the casing 2 is mud to improve the efficiency of excavation work. be able to. The excavated earth and sand containing water is discharged from the opening 21 of the casing 2 so as not to accumulate inside.

  Next, by rotating the casing 2 in the direction opposite to the direction when it is pushed in (the y direction shown in FIG. 5), the gripping claws 4 are rotated so that the front end portions 4A thereof are simultaneously moved into the casing 2 from the claw accommodating portions 70. (Fig. 7). In this state, when the pile pulling device 1 is pulled up by a crane truck, the tip 4A of the gripping claws 4 bites into and engages with the outer peripheral surface of the lower end of the existing pile P, and the lower end of the existing pile P is moved by the gripping claws 4. It is gripped (FIG. 9). When the pile pulling device 1 is pulled up, the gripping claws 4 are displaced downward along the support shaft 8 in order to receive the resistance U of the earth and sand through the protrusions 4D. Since each protrusion 90 engages with the engaging groove 91 (see FIG. 8), the rotation of the gripping claws 4 in the horizontal plane is completely restricted. In addition, after grasping the lower end part of the existing pile P with the tip part 4A of the grasping claw 4, the grasping claw 4 is pressed downward by the weight of the existing pile P (see FIG. 9). The engagement between each engagement groove 91 and each projection 90 is not released.

  Next, the rotation of the casing 2 is stopped, and the pile pulling device 1 is continuously pulled up by a crane truck in a state where the existing pile P is gripped by the gripping claws 4, so that the existing pile P is accommodated in the casing 2 in the ground. Can be pulled out from.

  According to this pile pulling apparatus 1, the gripping claws 4 are rotated in the horizontal plane by rotating the casing 2 in the forward and reverse directions in the ground, and the leading end 4 </ b> A of the gripping claws 4 appears and disappears from the inside of the casing 2. Since it operates, it is not necessary to provide a driving device such as a hydraulic cylinder in the casing 2 in order to move the gripping claws 4 in and out of the casing 2. In this way, since the configuration of the entire apparatus can be simplified and made compact, the weight of the entire pile extraction apparatus 1 can be reduced, the efficiency of the extraction work of the existing pile P can be improved, and the cost can be reduced. be able to.

In the above-described embodiment, the casing 2 is constituted by a single steel pipe having a predetermined length. However, as shown in FIG. 10, a plurality of pipes are connected in a vertical row via a connecting portion 22. And you may comprise one steel pipe.
The illustrated casing 2 includes an upper pipe 23 positioned at the uppermost portion of the casing 2, a lower pipe 24 positioned at the lowermost portion of the casing 2, and a plurality of pipes 25 for addition.

  On the upper surface of the upper pipe 23, there is provided a joint portion 20 that can be connected to the connecting portion 31 of the casing rotation drive device 3. Through the joint portion 20, the rotary drive shaft 30 is rotated and the crane 10 is moved up and down due to undulations. Transmission to the casing 2 is possible.

  The head portion 5 is integrally connected to the lower end portion of the lower pipe 24 by welding. Although not shown in the figure, the gripping claws 4 are provided on the head portion 5. The structure in which the gripping claw 4 is pivoted so that the tip end portion 4A protrudes into the casing 2 (head portion 5) or retreats to the outside of the casing 2 (head portion 5) is the same as the above-described embodiment. It is the same.

It is a side view which shows schematic structure of the pile drawing-out apparatus which is one Example of this invention. It is the front view which fractured | ruptured a part which expands and shows the structure of a casing. It is a bottom view of a casing. It is a plane sectional view expanding and showing composition in a head part when a grasping claw exists in a retreat position. It is a plane sectional view expanding and showing composition in a head part when a grasping claw is in an engagement position. It is a longitudinal cross-sectional view which follows the AA line of FIG. It is a longitudinal cross-sectional view which follows the BB line of FIG. 5 when pushing the casing in the ground. It is a longitudinal cross-sectional view which follows the BB line of FIG. 5 when pulling up a casing from underground. It is a longitudinal cross-sectional view which follows the BB line of FIG. 5 when pulling up a casing from underground. It is a side view which shows schematic structure of the pile drawing-out apparatus which is another Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pulling-out apparatus of the existing pile 2 Casing 3 Casing rotation drive device 4 Holding claw 4A Front end part 4B Rear end part 4C Shaft support part 4D Protrusion part 6 Excavation blade 7 Claw accommodation space 8 Support shaft 9 Anti-rotation mechanism 70 Claw accommodation part 71 Window hole Part 90 Projection 91 Engaging groove P Existing pile θ Rotation angle range

Claims (3)

A cylindrical casing that has a digging blade at the lower end to dig around the existing pile buried in the ground and is pushed into the ground so as to surround the existing pile, and the casing is forward and reverse around its central axis A rotation driving device capable of being driven to rotate in a direction, and at least one gripping claw provided in the casing so as to protrude into and retract from the casing so as to protrude into the casing and engage with a lower end of the existing pile. In an existing pile drawing device comprising:
The casing has a window hole portion for projecting the gripping claw in and out at a position where the gripping claw is provided,
The gripping claws are pivotally supported by the casing in the longitudinal direction so that they can freely rotate in a horizontal plane, and a portion ahead of the pivotal support projects into the casing and engages the lower end of the existing pile. Reciprocating between the angular position where it can be engaged and the angular position where it does not engage with the lower end of the existing pile, and the portion behind the shaft support portion remains protruding from the outer peripheral surface of the casing. An existing pile pulling device in which the length of the front and rear portions and the rotation angle range are set.   The inner surface of the casing can be fitted with a portion ahead of the shaft support portion of the grip claw when the portion ahead of the shaft support portion of the grip claw is at an angular position where it does not engage with the lower end of the existing pile. The pulling-out apparatus of the existing pile described in Claim 1 with which the nail | claw accommodating part was recessedly provided.   The gripping claw is pivotally supported so that it can be displaced in the vertical direction within the window hole, and the gap between the lower surface of the gripping claw and the opening lower edge of the window hole is ahead of the gripping claw pivot. A detent mechanism is provided that can engage with each other and restrict the rotation of the gripping claws when the portion is at an angular position where it can protrude into the casing and engage with the lower end of the existing pile. Item 3. An existing pile pulling device according to item 1 or 2.

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