JP5932595B2 - Pile insertion device and pile insertion method - Google Patents

Description

  The present invention relates to an apparatus and method for inserting a pile into the ground.

  In soft ground where the supporting force is weak, construction to increase the supporting force of the ground by inserting a steel pipe pile is performed (Patent Document 1). When inserting a steel pipe pile into the soil, it is known that if a heavy machine is used, the workability is good, and if the steel pipe pile is rotated, the insertion becomes easy. However, when a heavy machine cannot be carried in due to the presence of a structure, or when a heavy machine cannot be used due to a narrow space in the work site due to the shape of the structure, the technique described in Patent Document 1 is extremely difficult or impossible to apply. It is.

  In addition, for the purpose of preventing the occurrence of a landslide on the ground having a slope, a technique for discharging groundwater by inserting an iron pipe or a vinyl chloride pipe having a hole in the soil of the slope is known (Patent Document 2). . In this case, it is necessary to incline the pipe and insert it into the soil, but if there is a person's house in the vicinity of the slope, you must work in a narrow space between the slope and the person's house. It may not be possible to use heavy machinery.

  As mentioned above, when it is difficult or impossible to use heavy machinery due to the existence of existing structures and limited work space, it is possible to carry out construction work to increase the support capacity of the ground and drainage work on the slope As a technique intended to do this, there is a technique described in Patent Document 3. This technology is a technology in which a jack with high portability is installed between the structure and the ground, and the ready-made pile is driven by the jack using the reaction force of the structure. In this case, the ready-made pile is rotated. However, it is intended to be driven into the ground.

Japanese Patent Laid-Open No. 9-296446 JP 2007-327297 A JP 2009-13615 A

  However, in the technique of patent document 3, it becomes the structure which connects the jack for providing a driving force with respect to a ready-made pile, and the mechanism (linear motion rotation conversion mechanism) for rotating a ready-made pile in series. . Therefore, when applying this technique, it is necessary to secure a work space extending in the vertical direction at the lower part of the structure foundation, and the work amount for excavating the ground below the foundation increases accordingly.

  Further, as shown in FIG. 3 of Patent Document 3, the linear motion rotation conversion mechanism has a configuration in which a spiral member having a spiral curved surface is sandwiched between two restraining rods installed in parallel. In this mechanism, the thrust force of the jack is applied to the spiral member, and the axial rotation force is obtained from the axial force by the action. In such a configuration, the spiral member rotates while sliding between the fixed restraining rods and descends, the wear of the contact points of both is severe, and the contact mode of the contact points expands from point contact to surface contact. However, it is conceivable that the frictional force is remarkably increased. In order to obtain a large rotational force at the spiral portion, it is necessary to apply a large force in the axial direction. If a large force is applied in the axial direction, the frictional force increases and hinders shaft rotation, so a larger axial force is required. When a large force is applied to increase the rotational force in this way, there is a possibility that the rotation mechanism is locked.

  The linear motion rotation conversion mechanism shown in FIG. 11 of Patent Document 3 is configured such that the spiral member descends while sliding through a fixed gap having a rectangular width. In the gap, the spiral member descends while being in surface contact, and it is considered that a larger frictional force is generated than that in FIG. Moreover, the contact area of the surface contact is a mechanism that gradually increases, and it is considered that the passage of the spiral member becomes more difficult. Thus, in addition to requiring a large work space as described above, the technique of Patent Document 3 requires a very large axial force to rotate the pile, or rotates the pile. It is thought that it has the subject that it is very difficult to make it.

  Accordingly, an object of the present invention is to provide a pile insertion device and a pile insertion method that can be inserted into the ground while rotating a pile even in a relatively narrow space by using a hydraulic cylinder having high portability. is there.

As a result of intensive studies to solve the above problems, the present inventors have come up with the following aspects.
That is, a pile insertion device for inserting a pile according to the first aspect of the present invention,
A hydraulic cylinder having a cylinder body and a rod installed on the inner peripheral side of the cylinder body, the hydraulic cylinder being extendable by relative displacement between the cylinder body and the rod;
A cylindrical portion installed on the outer peripheral side of the hydraulic cylinder, the cylindrical portion having an axis substantially parallel to an extension direction of the hydraulic cylinder, and the hydraulic cylinder when the hydraulic cylinder extends A guide member having a force receiving portion for receiving the axial pressing force from the pile insertion device,
The cylindrical portion has a helical groove;
The cylinder body has a protrusion on the outer peripheral surface to be inserted into the spiral groove,
When the hydraulic cylinder expands and presses the force receiving portion, the guide member is propelled in the axial direction, thereby applying a circumferential force from the protrusion to the edge of the spiral groove. By this, it is a pile insertion apparatus with which the said guide member rotates relatively with respect to the said cylinder main body.

  According to the pile insertion device having the above configuration, the guide member can be propelled in the axial direction by rotating the hydraulic cylinder. Therefore, if the pile is coaxially connected to the end of the guide member, the pile can be propelled in the axial direction by rotating the hydraulic cylinder. Therefore, even in a place where it is difficult to secure a wide working space, it is possible to insert the pile into the soil while rotating the pile using a highly portable hydraulic cylinder. Furthermore, since the cylindrical portion of the guide member is arranged on the outer peripheral side of the hydraulic cylinder, as compared with the configuration in which the jack and the linear motion rotation conversion mechanism are arranged in series as in Patent Document 3 above. The vertical dimension of the space required for the work is shortened, and the load of excavation work for securing the work space is reduced. Furthermore, since the projecting portion and the spiral groove are in contact with each other in a relatively small area and the frictional force between them is reduced, the axial driving force can be efficiently converted into rotational force and smoothly It is possible to rotate the pile.

A pile insertion device for inserting a pile according to the second aspect of the present invention,
A hydraulic cylinder having a cylinder body and a rod installed on the inner peripheral side of the cylinder body, the hydraulic cylinder having a hydraulic cylinder that can be extended by relative displacement between the cylinder body and the rod;
The cylinder body has a spiral groove on its inner peripheral surface,
The rod has a protrusion on its outer peripheral surface to be inserted into the spiral groove,
When the hydraulic cylinder is extended, the protrusion is displaced along the spiral groove, whereby the rod is pushed out while rotating relative to the cylinder body.
Even with such a configuration, the same effect as that of the first aspect can be obtained.

  According to a third aspect of the present invention, in the above pile insertion device, the hydraulic cylinder has a roller attached to the protrusion, and the protrusion is inserted into the spiral groove via the roller. Is done. By carrying out like this, the relative displacement of a projection part and a spiral groove can be made smoother, and it becomes possible to rotate a pile more smoothly.

A pile insertion method for inserting a pile into the ground from the lower surface of the structure according to the fourth aspect of the present invention downward,
Fixing the hydraulic cylinder to the lower surface of the structure so as to extend downward from the lower surface of the structure;
A step of installing a guide member having a cylindrical portion having a spiral groove and a force receiving portion for receiving a pressing force in the axial direction from the hydraulic cylinder, the cylindrical portion having the shaft of the hydraulic cylinder; The guide member is installed on the outer peripheral side of the hydraulic cylinder so as to be substantially parallel to the extending direction, and the projection member provided on the outer peripheral surface of the hydraulic cylinder is inserted into the spiral groove. Steps,
Connecting the pile to the guide member;
The hydraulic cylinder is extended to exert a downward pressing force on the force receiving portion to propel the guide member downward, and at that time, the protrusion is applied to the edge of the spiral groove. And a step of rotating the guide member relative to the hydraulic cylinder by a circumferential force to be inserted into the ground while rotating the pile.

  According to the above pile insertion method, even in a place where it is difficult to ensure a wide working space, it is possible to insert the pile into the soil while rotating the pile using a highly portable hydraulic cylinder. . Furthermore, since the cylindrical portion of the guide member is arranged on the outer peripheral side of the hydraulic cylinder, the vertical dimension of the space required for the work is shortened, and the work space is secured at the lower part of the structure. The load of excavation work is reduced.

A pile insertion method for inserting a pile into the ground from the lower surface of the structure according to the fifth aspect of the present invention downward,
A hydraulic cylinder having a cylinder main body and a rod installed on the inner peripheral side of the cylinder main body, and is extendable by relative displacement between the cylinder main body and the rod, the cylinder main body on the inner peripheral surface thereof The hydraulic cylinder, which has a helical groove and the rod has a protrusion inserted into the helical groove on the outer peripheral surface thereof, can be extended downward from the lower surface of the structure. Fixing to the lower surface of the structure;
Connecting the pile to the rod;
The rod is pushed out to extend the hydraulic cylinder, thereby displacing the protrusion along the spiral groove, thereby rotating the rod relative to the cylinder body, thereby rotating the pile while rotating the pile. And a step of inserting the pile into the pile.
Even with such a configuration, the same effects as those of the fourth aspect described above can be obtained.

FIG. 1 is a view showing a pile insertion device according to an embodiment of the present invention, FIG. 1 (A) is a front view, and FIG. 1 (B) is seen along the direction of arrow IB in FIG. 1 (A). FIG. 1C is a cross-sectional view taken along one-dot chain line IC in FIG. 1B. Drawing 2 is a figure when the pile insertion device by one embodiment is extended, Drawing 2 (A) is a front view and Drawing 2 (B) is a sectional view. FIG. 3 is a schematic diagram showing an example of a method for inserting a pile into the soil below the structure using the pile insertion device of the present embodiment. FIG. 4 is a schematic diagram showing an example of a method of inserting a pile by the pile insertion device of this embodiment in an underground pit of a structure. FIG. 5 is a schematic view showing an example of a method for inserting a steel pipe by the pile insertion device of the present embodiment in order to reinforce an existing pile. FIG. 6 is a view showing a pile insertion device according to a second embodiment of the present invention, FIG. 6 (A) is a front view, and FIG. 6 (B) is a sectional view.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a view showing a pile insertion device 1 according to this embodiment. FIG. 1 (A) is a front view of the pile insertion device 1, and FIG. 1 (B) is a top view of the pile insertion device 1 viewed in the direction of arrow IB in FIG. 1 (A). C) is a cross-sectional view taken along one-dot chain line IC in FIG. As shown in FIG. 1A, the pile insertion device 1 of the present embodiment includes a hydraulic cylinder 10, a substantially cylindrical guide member 20, a hydraulic hose 30, and a base 40.
As shown in the drawing, the guide member 20 includes a cylindrical portion 21 and a force receiving portion 22 that forms one axial end face thereof, and the cylindrical portion 21 is installed so as to cover the outer periphery of the hydraulic cylinder 10. The cylindrical portion 21 is formed with a continuous spiral groove (hereinafter referred to as a spiral groove 23).

  The hydraulic cylinder 10 has a cylinder body 11, a piston 12 installed on the inner peripheral side thereof, and a piston rod 13 integrated with the piston 12. On the outer peripheral surface of the cylinder body 11, a cylindrical protrusion 14 that protrudes toward the outer periphery is formed, and the protrusion 14 is inserted into the spiral groove 23.

  A hydraulic path 31 is formed inside the hydraulic hose 30, and an opening on one end side is a hydraulic inlet / outlet 32. A hydraulic pressure supply / discharge path (not shown) is connected to the hydraulic inlet / outlet 32, and with this configuration, hydraulic pressure is supplied from a hydraulic source (not shown) to the hydraulic chamber 17 (see FIG. 2) of the hydraulic cylinder 10. In addition, the hydraulic pressure can be discharged from the hydraulic chamber 17. The base 40 is formed as a flat member and is integrally fixed to the base end side of the cylinder body 11.

  FIG. 2 shows an operation example when hydraulic pressure is supplied to the pile insertion device 1 having the above configuration via the hydraulic hose 30. 2A is a front view, and FIG. 2B is a cross-sectional view. When hydraulic pressure is supplied to the hydraulic cylinder 10 of the pile insertion device 1, hydraulic fluid (hydraulic oil) is supplied to the hydraulic chamber 17 of the hydraulic cylinder 10, and the volume of the hydraulic chamber 17 is increased. The hydraulic chamber 17 is a space defined by the inner peripheral surface of the cylinder body 11 and the end surface of the piston 12 opposite to the piston rod 13. By expanding the volume of the hydraulic chamber 17, the piston rod 13 is pushed out from the cylinder body 11 in the axial direction, so that the hydraulic cylinder 10 extends. Then, the tip 18 of the piston rod 13 pushes the force receiving portion 22 of the guide member 20 through the cradle 19, thereby propelling the entire guide member 20 in the axial direction.

Since the protrusion 14 of the hydraulic cylinder 10 is inserted into the spiral groove 23 of the guide member 20, when the guide member 20 is propelled as described above, the protrusion 14 contacts the edge of the spiral groove 23, and A force (reaction force) is applied to the edge. As is clear from FIGS. 1 and 2, the tangent of the edge at an arbitrary position of the edge of the spiral groove 23 (except for the vicinity of the end of the spiral groove 23) is inclined with respect to the propulsion direction of the guide member 20. Yes. Therefore, the force that the protrusion 14 gives to the edge of the spiral groove 23 that is the contact partner can be decomposed into an axial force and a circumferential force (rotational force). When the circumferential force acts as a rotational force, the guide member 20 rotates relative to the cylinder body 11. Therefore, when the guide member 20 is pushed out by the piston rod 13 of the hydraulic cylinder 10, the guide member 20 is pushed out while rotating. FIG. 2 shows a state in which the hydraulic cylinder 10 is extended from the state of FIG. 1 and the guide member 20 is pushed out to rotate about two times (that is, about 720 °).
In the illustrated example, the spiral groove 23 penetrates the guide member 20. However, the present invention is not limited to this, and the spiral groove 23 is formed only on the inner peripheral surface of the cylindrical portion 21 of the guide member 20, and penetrates. It is also possible not to.

  The cradle 19 is disposed on the inner surface side of the force receiving portion 22, but is not fixed to the inner surface of the force receiving portion 22. Thereby, relative rotation between the guide member 20 and the piston rod 13 is enabled. In such a configuration, when the hydraulic oil is discharged from the hydraulic chamber 17 and the piston rod 13 is accommodated, the protrusion 14 is inserted into the spiral groove 23, so that the guide member 20 rotates in the opposite direction. Finally, the state returns to the state of FIG.

Next, a plurality of examples of a pile insertion method using the pile insertion device 1 of the present embodiment will be described with reference to FIGS. In addition, illustration is abbreviate | omitted about the path | route and apparatus for supplying hydraulic_pressure | hydraulic with respect to the pile insertion apparatus 1, and discharging | emitting hydraulic pressure from the apparatus 1. FIG.
FIG. 3 is a schematic diagram when a pile is inserted into the ground below the structure 50. As shown in FIG. 3A, excavation work is performed to provide a necessary work space below the structure 50. In the upper part of the pile driving position, the base 40 is firmly fixed to the lower surface of the structure 50 with bolts or the like (not shown) with the pile insertion device 1 facing upward. And the pile 60 inserted initially is connected so that these may become coaxial with respect to the front-end | tip part of the guide member 20. As shown in FIG. In order to perform the connection, an appropriate method such as screwing or fitting can be used.

  Thereafter, the hydraulic cylinder 10 is extended by supplying hydraulic pressure, and the guide member 20 is propelled downward while rotating. Thereby, since the pile 60 is also propelled downward while rotating simultaneously, the pile 60 is inserted into the soil while rotating. FIG. 3B shows a state in which the hydraulic cylinder 10 is extended to the maximum (for the maximum stroke) and the pile 60 is inserted into the soil. If it will be in this state, connection with the guide member 20 and the pile 60 will be released | released, hydraulic pressure will be discharged | emitted from the hydraulic cylinder 10, and the hydraulic cylinder 10 will be shortened to the original state. Then, as shown in FIG. 3C, the next pile 61 is inserted into the gap between the inserted first pile 60 and the guide member 20. In this case, by setting the length of the next pile 61 to be equal to or shorter than the maximum stroke length of the hydraulic cylinder 10, it is possible to insert into the gap. The lower end of the pile 61 is fixedly connected to the upper end of the first pile 60 by welding or the like, and the upper end of the next pile 61 is connected to the end of the guide member 20 in the same manner as the first pile 60. . Then, by extending the hydraulic cylinder 10 again from such a state, the first pile 60 and the next pile 61 can be inserted into the soil while being integrally rotated. By repeating the same work, the piles are sequentially added, rotated and inserted into the soil, and the work is finished when the tip of the pile reaches a predetermined depth. In addition, as the height of the work space to prepare, it is necessary to ensure the dimension more than the sum total length of the length of the pile insertion apparatus 1 when shortened most and the largest length of each pile. In the example of FIG. 3, the length of each pile was made the same.

  FIG. 4 is a schematic diagram when a pile is inserted in an underground pit of a structure. When the ground is not exposed, the bottom concrete 70 is removed by a necessary size as shown in FIG. 4A to expose the ground. At the upper part, the base 40 is firmly fixed to the upper concrete 80 of the underground pit with bolts or the like (not shown) with the pile insertion device 1 facing upward. Then, the pile 60 is coaxially connected to the tip of the guide member 20. In order to perform this connection, an appropriate method such as screwing or fitting can be used. Thereafter, by performing the same operation as in FIG. 3, the piles are sequentially added as shown in FIGS. 4 (B) and 4 (C), and the ground is rotated integrally until the necessary depth is reached. Can be inserted inside.

  FIG. 5 is a schematic diagram of a steel pipe insertion operation when reinforcing an existing pile of a structure. In many structures, piles made of reinforced concrete are driven into the basement of the structure in accordance with the Building Standards Act when building the structure. However, when extending the structure, it is necessary to reinforce the existing pile. In such a case, the steel pipes 100 and 101 having larger diameters are sequentially inserted to the necessary depth by the above-described method so as to expose a portion where the existing pile 90 is present and cover the existing pile 90 from the outer periphery. The pile is reinforced by covering the existing pile 90 with the steel pipes 100 and 101. If it is the method of this invention, if an airspace a little wider than the movable range of the pile insertion apparatus 1 can be ensured, a steel pipe can be inserted by working while connecting a short steel pipe.

  Although not shown, if the pile insertion device 1 is installed so as to push out the piston rod 13 in the oblique direction, the pile and other rod-shaped members can be obliquely inserted into the soil, and water for preventing landslides can be obtained. The present invention can be used for insertion of a pipe for extraction.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. Unlike the first embodiment, the pile insertion device 100 of the present embodiment employs a configuration in which the protrusions 14 are provided on the outer peripheral surface of the piston 12. The cylinder body 11 is constituted by an inner cylinder 111 on the inner peripheral side and an outer cylinder 112 on the outer peripheral side, and a continuous spiral groove 123 is formed in the inner cylinder 111. The cylinder body 11 is formed by integrating the outer cylinder 112 so that the outer periphery of the inner cylinder 111 is liquid-tightly covered with the outer cylinder 112. In the example of FIG. 6, the inner cylinder 111 and the outer cylinder 112 are prepared as separate bodies and are configured to be integrated with each other. However, the cylinder body 11 as an integrated body is prepared from the beginning, and only the inner peripheral surface thereof is prepared. Alternatively, the continuous spiral groove 123 may be recessed as a groove that does not penetrate.

On the other hand, the cylindrical protrusion 14 is formed so as to protrude from the outer peripheral surface of the piston 12 and is inserted into the spiral groove 123 on the inner peripheral surface of the cylinder body 11.
When the hydraulic pressure is supplied via the hydraulic hose 30, the piston 12 is pressed and the piston rod 13 is pushed out. At this time, since the protrusion 14 is inserted into the spiral groove 123, the protrusion 14 is displaced along the spiral groove 123, whereby the piston 12 and the piston rod 13 rotate. Therefore, the piston rod 13 is pushed out while rotating.

  If the pile is coaxially attached to the tip end portion 18 of the piston rod 13 so as not to be relatively rotatable, the pile can be propelled while being rotated by the extension of the hydraulic cylinder 10. Thus, the pile insertion device 100 of the second embodiment can be inserted into the soil while rotating the pile by using the same operation instead of the pile insertion device 1 of the first embodiment. Therefore, the pile insertion apparatus 100 of 2nd Embodiment can be used similarly for a use as shown to FIGS.

(Modification)
It is also possible to use a hydraulic jack instead of the hydraulic cylinder 10 of the first embodiment or as an example thereof.
As a modified example of each of the above embodiments, a roller may be attached to the protrusion 14 of the hydraulic cylinder 10 and the protrusion 14 may be inserted into the spiral grooves 23 and 123 via the roller. By carrying out like this, the relative displacement of the projection part 14 and the spiral grooves 23 and 123 can be made smoother, which is preferable.

  The number of turns of the spiral grooves 23 and 123 shown in the drawings of the above embodiments (that is, the number of times the spiral grooves 23 and 123 circulate around the cylindrical portion 21 or the inner cylinder 111 (or the inner peripheral surface of the cylinder body 11)). Is merely an example, and can be arbitrarily set as necessary within a range that can be actually used as the pile insertion devices 1 and 100. The number of spiral grooves 23 and 123 is not limited to one, and a plurality of spiral grooves 23 and 123 may be formed in the cylindrical portion 21 or the inner cylinder 111 (or the inner peripheral surface of the cylinder body 11). In this case, a larger rotational force can be obtained.

  The pitch of the spiral grooves 23 and 123 can also be changed as necessary. Particularly, in the first embodiment, a plurality of types of guide members 20 having spiral grooves 23 having different pitches are prepared, and each time depending on the properties of the ground to be worked on and the pushing force of the hydraulic cylinder 10 to be used. A use mode in which the guide member 20 having the spiral groove 23 having an optimal pitch is selected and used (used after being replaced) is also possible.

  The present invention is not limited to the description of the embodiments and examples of the invention described above. Various modifications are also included in the present invention as long as those skilled in the art can easily conceive without departing from the scope of the claims.

DESCRIPTION OF SYMBOLS 1,100 Pile insertion apparatus 10 Hydraulic cylinder 11 Cylinder main body 12 Piston 13 Piston rod 14 Protrusion part 20 Guide member 21 Cylindrical part 22 Power receiving part 23, 123 Spiral groove 30 Hydraulic hose 40 Base 60, 61 Pile 90 Existing pile 100, 101 Steel pipe

Claims (5)

In a pile insertion device for inserting a pile,
A hydraulic cylinder having a cylinder body and a rod installed on the inner peripheral side of the cylinder body, the hydraulic cylinder being extendable by relative displacement between the cylinder body and the rod;
A cylindrical portion installed on the outer peripheral side of the hydraulic cylinder, the cylindrical portion having an axis substantially parallel to an extension direction of the hydraulic cylinder, and the hydraulic cylinder when the hydraulic cylinder extends A guide member having a force receiving portion for receiving the axial pressing force from the pile insertion device,
The cylindrical portion has a helical groove;
The cylinder body has a protrusion on the outer peripheral surface to be inserted into the spiral groove,
When the hydraulic cylinder expands and presses the force receiving portion, the guide member is propelled in the axial direction, thereby applying a circumferential force from the protrusion to the edge of the spiral groove. Accordingly, the pile insertion device in which the guide member rotates relative to the cylinder body. A pile insertion device for inserting a pile,
A hydraulic cylinder having a cylinder body and a rod installed on the inner peripheral side of the cylinder body, the hydraulic cylinder having a hydraulic cylinder that can be extended by relative displacement between the cylinder body and the rod;
The cylinder body has a spiral groove on its inner peripheral surface,
The rod has a protrusion on its outer peripheral surface to be inserted into the spiral groove,
When the hydraulic cylinder is extended, the protrusion is displaced along the spiral groove, whereby the rod is pushed out while rotating relative to the cylinder body. The hydraulic cylinder has a roller attached to the protrusion,
The pile insertion device according to claim 1 or 2, wherein the protrusion is inserted into the spiral groove via the roller. A pile insertion method for inserting a pile into the ground downward from the bottom surface of the structure,
Fixing the hydraulic cylinder to the lower surface of the structure so as to extend downward from the lower surface of the structure;
A step of installing a guide member having a cylindrical portion having a spiral groove and a force receiving portion for receiving a pressing force in the axial direction from the hydraulic cylinder, the cylindrical portion having the shaft of the hydraulic cylinder; The guide member is installed on the outer peripheral side of the hydraulic cylinder so as to be substantially parallel to the extending direction, and the projection member provided on the outer peripheral surface of the hydraulic cylinder is inserted into the spiral groove. Steps,
Connecting the pile to the guide member;
The hydraulic cylinder is extended to exert a downward pressing force on the force receiving portion to propel the guide member downward, and at that time, the protrusion is applied to the edge of the spiral groove. A pile insertion method comprising: rotating the guide member relative to the hydraulic cylinder by a circumferential force to be inserted, and thereby inserting the pile into the ground while rotating the pile. A pile insertion method for inserting a pile into the ground downward from the bottom surface of the structure,
A hydraulic cylinder having a cylinder main body and a rod installed on the inner peripheral side of the cylinder main body, and is extendable by relative displacement between the cylinder main body and the rod, the cylinder main body on the inner peripheral surface thereof The hydraulic cylinder, which has a helical groove and the rod has a protrusion inserted into the helical groove on the outer peripheral surface thereof, can be extended downward from the lower surface of the structure. Fixing to the lower surface of the structure;
Connecting the pile to the rod;
The rod is pushed out to extend the hydraulic cylinder, thereby displacing the protrusion along the spiral groove, thereby rotating the rod relative to the cylinder body, thereby rotating the pile while rotating the pile. A pile insertion method comprising: inserting into the pile.

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