JP7017763B2 - How to pull out steel pipe piles and steel pipe piles - Google Patents

Description

The present invention relates to a steel pipe pile, a connecting rod, and a method for pulling out a steel pipe pile, in particular, a steel pipe pile having an engaging portion at the tip, a connecting rod that can be connected to the engaging portion of the steel pipe pile, and a steel pipe via the connection between the two. The present invention relates to a method of pulling out a steel pipe pile to be pulled out by applying a rotational force and a pulling force to the tip of the pile.

A method of burying steel pipe piles in the foundation ground of a building to support the foundation of the building and a method of reinforcing the ground are widely used.
In these construction methods, straight steel pipe piles and steel pipe piles with tip wings with auger blades attached to the outer circumference of the tip are used, and a construction machine placed on the ground applies rotational force around the axis to the steel pipe piles in the digging direction. Propulsion penetrates the steel pipe pile into the ground and allows the tip of the pile to reach the supporting ground. If the supporting ground is deep, steel pipe piles are added by welding or non-welding type mechanical joints.

When buying or selling land with buried steel pipe piles or rebuilding a building, it is necessary to pull out and remove the steel pipe piles buried in the ground. For example, the following methods exist for removing steel pipe piles.
<1> A method of pulling out with a gripping device.
A gripping device is fixed to the head of the steel pipe pile exposed from the ground, the wire is connected, and the wire is lifted by a lifting machine such as a crane to pull out the steel pipe pile in a straight line. This method is mainly applied to straight steel pipe piles.
<2> Method by rotary pulling out.
The steel pipe head is pulled out by applying propulsive force to the ground side while applying rotation in the opposite direction to that at the time of burying by the construction machine. This method is mainly applied to steel pipe piles with tip wings, but can also be used for straight steel pipe piles.
<3> Method by covering digging (Patent Document 1).
A casing whose inner diameter is larger than the outer diameter of the steel pipe pile is rotationally press-fitted to the outside of the steel pipe pile, the edge between the circumference of the steel pipe pile and the ground outside the casing is cut, and the head of the steel pipe pile is gripped by a gripping device to lift the machine. Pull out with. This method can be applied to both straight steel pipe piles and steel pipe piles with tip wings.

Japanese Unexamined Patent Publication No. 2008-8146

The prior art has the following problems.
<1> In the method of pulling out with a gripping device, since the steel pipe pile restrained in the ground is pulled out in a straight line, a large pulling force exceeding the peripheral friction force of the steel pipe pile is required. Therefore, when the steel pipe piles are connected by welding or mechanical joints, stress is concentrated on the joint portion and the joints are damaged due to the pulling out, and the tip side of the steel pipe piles may be left in the ground. If the steel pipe pile is left in the ground, it is very difficult to dig it up and remove it because it is difficult to identify the position of the steel pipe pile in the ground and the hole is bent, which requires a lot of labor and cost. It takes.
<2> In the rotary pull-out method, in order to transmit the rotational force from the construction machine placed on the ground to the tip of the steel pipe pile, the friction between the peripheral surface of the steel pipe pile and the ground is applied from the head of the steel pipe pile to the tip. It is necessary to cut the edges one by one. However, due to the restoration of the ground during the service period, pulling out requires a larger force than at the time of penetration, so there is a risk that the joint portion of the steel pipe pile will be damaged and the tip will be left in the ground due to rotation. If the tip of the steel pipe pile remains in the ground, the same problem as in <1> occurs.
<3> In the method of digging a cover, the tip of the casing comes into contact with the outer circumference of the steel pipe pile when the casing is press-fitted, so that the steel pipe pile may be cut. If the tip of the steel pipe pile remains in the ground, the same problem as in <1> occurs.
<4> In order to prevent contact between the casing and the steel pipe pile, it is necessary to secure a sufficient clearance between the inner surface of the casing and the outer surface of the steel pipe pile. Therefore, considering the bending of the hole at the time of driving the steel pipe pile and the deviation of the axial center from the drilling machine, it is necessary to increase the inner diameter of the casing as the steel pipe pile becomes longer. This requires a large rotary press-fitting device, which increases the construction cost. In addition, if the size of the device becomes large, it cannot be installed in a narrow residential site.
<5> The large outer diameter of the casing may disturb a wide range of ground and cause a decrease in ground strength.

An object of the present invention is to provide a steel pipe pile, a connecting rod, and a method for pulling out a steel pipe pile, which can solve the above-mentioned problems of the prior art.

The steel pipe pile of the present invention includes a hollow pile body and an engaging portion provided at the tip of the pile body, and the engaging portion includes an engaging space communicating with the inside of the pipe of the pile body and an inner surface of the engaging portion. The engaging means has a structure capable of engaging with the connecting end by inserting the connecting end of the tip of the connecting rod into the engaging space and rotating the engaging means. It is characterized in that the rotational force and the pulling force of the connecting rod can be transmitted through the engagement between the portion and the connecting end.

In the steel pipe pile of the present invention, the engaging means is a protrusion or a keyway, and a keyway or a protrusion is provided on the outer periphery of the connecting end of the connecting rod, and the keyway or the key of the connecting end of the engaging means is provided. The groove is continuous with the first part that allows the relative movement of the protrusion of the connecting end or the protrusion of the engaging means due to the insertion of the connecting end into the engaging space, and is continuous with the first part, and the groove is formed in the engaging space of the connecting end. It may have a second portion that allows relative movement of the protrusion of the connecting end or the protrusion of the engaging means with rotation.

The steel pipe pile of the present invention has a hollow flow path pipe in which the engaging portion communicates with the side surface of the engaging portion in a direction orthogonal to the longitudinal direction of the pile body and crosses the engaging space. May be located at a height at which the connecting end of the connecting rod is pushed toward the tip end side of the engaging portion by the connecting end in a state of being engaged with the engaging portion.

The connecting rod of the present invention includes a hollow rod body that can be inserted into the pipe from the head of the steel pipe pile and a connecting end attached to the tip of the rod body. It has a structure that can be engaged with the engaging part by inserting it into the engaging part of the steel pipe and rotating it, and the rotational force and pulling force of the connecting rod are applied to the steel pipe through the engagement between the connecting end and the engaging part. It is characterized by being configured so that it can be transmitted to the pile.

The method of pulling out the steel pipe pile of the present invention is to insert the connecting rod into the pipe of the pile body from the head of the steel pipe pile and insert the connecting end into the engaging portion. A rotational force around the shaft is applied to engage the connecting end with the engaging portion to connect them, and a construction machine applies a rotational force around the shaft to the engaging portion via the connecting rod. Then, the edge cutting process of cutting the edge between the steel pipe pile and the surrounding ground, and the pulling process of pulling out the steel pipe pile while applying the rotational force and the pulling force around the axis to the steel pipe pile via the connecting rod by the construction machine. It is characterized by being prepared.

In the method of pulling out the steel pipe pile of the present invention, excavated water may be sent from the engaging portion to the ground around the engaging portion via the inside of the connecting rod in the edge cutting step.

From the above configuration, the steel pipe pile, the connecting rod, and the method for pulling out the steel pipe pile of the present invention have at least one of the following effects.
<1> Since the rotational force and the pulling force can be directly applied to the tip of the steel pipe pile that is most tightly restrained, the steel pipe pile can be pulled out with a relatively small force even in a tightly tightened ground.
<2> The steel pipe pile can be efficiently pulled out by pulling out from the tip side of the steel pipe pile after cutting the edge with the ground over the entire length of the steel pipe pile.
<3> Since the steel pipe pile is pulled out from the tip side, the pulling force acts as a compressive force on the joint portion, and stress in the tensile direction is not applied. Therefore, the joint portion is less likely to be damaged and the steel pipe pile is less likely to be disassembled.
<4> Since the steel pipe pile is pulled out from the tip side, even if the joint portion is damaged, the tip of the steel pipe pile is not left in the ground and can be reliably recovered.
<5> Since no casing is used, it is possible to suppress the occurrence of problems such as leaving the tip due to cutting of steel pipe piles, soaring construction costs, and reducing ground strength due to disturbing a wide range of ground.

Explanatory drawing of the steel pipe pile and connecting rod of this invention. Explanatory drawing of the engaging portion and the connecting end. Explanatory drawing of the flow path pipe. The flow chart of the drawing method of the steel pipe pile of this invention. Explanatory drawing (1) of the drawing method of the steel pipe pile of this invention. Explanatory drawing (2) of the drawing method of the steel pipe pile of this invention.

Hereinafter, the steel pipe pile, the connecting rod, and the method for pulling out the steel pipe pile of the present invention will be described in detail with reference to the drawings.
In addition, each direction such as "up", "down", "vertical", "horizontal" in this specification means each direction at the time of carrying out of this invention, that is, each direction in FIGS. 5A and 5B.
Further, in the present specification, the "head" of the steel pipe pile and the connecting rod is the upper end portion in the state where the connecting rod is connected in the steel pipe pile buried in the ground, and the "tip" is the same. Each means the lower end in the state.

[Steel pipe piles and connecting rods]
<1> Steel pipe pile (Fig. 1).
The steel pipe pile 10 according to the present invention is a pile body including a hollow pile main body 11 and an engaging portion 12 provided at the tip of the pile main body 11.
In this example, as the steel pipe pile 10, a straight steel pipe pile in which a plurality of single steel pipes are connected in the longitudinal direction by welding is adopted.
However, the steel pipe pile 10 is not limited to this, and may be a steel pipe pile with a tip wing having an auger blade attached to the outer periphery of the tip.
Further, the steel pipe pile 10 is not limited to the connecting structure by welding, but may be a structure in which the connecting rod 20 is connected via a non-welding type joint material through which the connecting rod 20 can be inserted, or is not a connecting structure but an integrated structure. May be good.
The steel pipe pile 10 of this example further includes a flow path pipe 13 that communicates the side surface of the engaging portion 12 in a direction orthogonal to the longitudinal direction of the pile body 11.

<1.1> Engaging portion (Fig. 2).
The engaging portion 12 is a component for engaging and connecting with the connecting rod 20.
The engaging portion 12 has at least an engaging means 12a provided on the inner surface of the engaging portion 12 and an engaging space 12c communicating with the inside of the pipe of the pile body 11.
In this example, the engaging portion 12 has a closed structure further having a closed end 12b that closes the tip of the engaging space 12c.
In this example, a steel cap-shaped member welded to the tip of the pile body 11 is used as the engaging portion 12. In addition, as the engaging portion 12, for example, a structure integrated with the pile body 11 in which the engaging means 12a is formed on the inner surface of the tip of the steel pipe pile 10 or a tip equipped with a cutting blade having the engaging means 12 formed on the inner surface. A structure in which the bit is integrated with the pile body 11 by welding or the like may be adopted.

<1.1.1> Engagement means (FIG. 2).
The engaging means 12a is a component for engaging with the connecting means 22a of the connecting rod 20 described later.
The engaging means 12a has a structure capable of engaging with the connecting means 22a by inserting the connecting end 22 at the tip of the connecting rod 20 into the engaging space 12c and rotating the engaging means 12a.
In this example, as the engaging means 12a, a pair of rectangular block bodies protruding from the inner surface of the engaging portion 12 are adopted. The pair of block bodies are provided on both opposite sides of the inner surface of the engaging portion 12.
The connecting structure between the engaging means 12a and the connecting means 22a will be described later.

<1.2> Flow tube (Fig. 3).
The flow path pipe 13 is a component for forming a flow path of the filler A and the excavated water B by pushing the connecting rod 20.
The flow path tube 13 is made of a hollow tubular body. In this example, a thin stainless steel tube is used as the flow path tube 13.
The flow path pipe 13 communicates the side surface of the engaging portion 12 in a direction orthogonal to the longitudinal direction of the pile body 11. Specifically, both ends of the flow path pipe 13 communicate with both sides of the engaging portion 12, and the central portion of the flow path pipe 13 crosses the inside of the engaging space 12c.
The flow path pipe 13 is sheared by pushing the connecting end 22 of the connecting rod 20, which will be described later, into the engaging space 12c, and can form a flow path that communicates the engaging space 12c with the outside of the engaging portion 12. And. Specifically, the flow path pipe 13 is placed at a height such that it can be pushed and deformed by the connecting end 22 toward the closed end 12b in a state of being engaged with the engaging portion 12 and sheared.
Further, in order to facilitate the push-in deformation of the flow path pipe 13, a groove or the like may be provided on the outer peripheral surface of the flow path pipe 13 within the wall thickness.

<2> Connecting rod (Fig. 1).
The connecting rod 20 is a component for connecting to and pulling out the steel pipe pile 10.
The connecting rod 20 includes a rod main body 21, a connecting end 22 attached to the tip of the rod main body 21, and a liquid feeding path 23 that communicates the inside of the rod main body 21 and the connecting end 22 along the longitudinal direction.
The length of the connecting rod 20 is such that the connecting end 22 can be reached in the engaging portion 12 by inserting it into the pipe from the head of the steel pipe pile 10 buried in the ground.
The filler A, excavated water B, and the like can be pressure-fed from the head of the rod body 21 to the connecting end 22 by the liquid feeding path 23 and discharged from the tip of the connecting end 22.

<2.1> Connecting end (Fig. 2).
The connecting end 22 is a component for engaging and connecting with the steel pipe pile 10.
A connecting means 22a is provided on the outer periphery of the connecting end 22.
In this example, the connecting end 22 is screw-engaged to the tip of the rod body 21 to be connected, but the structure may be integrated with the rod body 21.

<2.1.1> Connecting means (Fig. 2).
The connecting means 22a is a component for engaging with the engaging means 12a of the steel pipe pile 10.
The connecting means 22a has a structure capable of engaging with the engaging means 12a by inserting the connecting end 22 into the engaging space 12c and rotating the connecting end 22a.
In this example, as the connecting means 22a, a pair of key grooves formed on both side surfaces on the outer circumference of the connecting end 22 is adopted.
Each pair of key grooves consists of a first portion 22b extending from the tip of the connecting end 22 toward the base end, and a second portion 22c continuous with the first portion 22b and extending in the circumferential direction of the connecting end 22. ..
The pair of first portions 22b are arranged at positions corresponding to the pair of block bodies of the engaging means 12a, and the groove width of the first portion 22b is wider than the width of the block body of the engaging means 12a.
The pair of second portions 22c extend from the tip end side of the first portion 22b in the same direction with respect to the circumferential direction of the connecting end 22, and the groove width of the second portion 22c is larger than the length of the block body of the engaging means 12a. wide.
The connecting structure of the engaging means 12a and the connecting means 22a is not limited to this example. For example, contrary to this example, the engaging means 12a may be used as a keyway and the connecting means 22a may be used as a block body. In short, the structure may be such that both can be connected through the engagement between the engaging means 12a and the connecting means 22a, and the rotational force and the pulling force of the connecting rod 20 can be transmitted to the steel pipe pile 10.
Further, an example in which the engaging means 12a and the connecting means 22a have a screwed structure will be described later in the second embodiment.

[How to pull out steel pipe piles]
<1> Overall configuration (Fig. 4).
The method for pulling out a steel pipe pile of the present invention is a method for pulling out and removing a steel pipe pile 10 buried in the ground using a connecting rod 20 and a construction machine 30.
The method for pulling out the steel pipe pile of the present invention is at least an insertion step S2 for inserting the connecting rod 20 inside the steel pipe pile 10, a connecting step S3 for engaging and connecting the connecting rod 20 with the steel pipe pile 10, and a steel pipe pile. It is provided with an edge cutting step S4 for cutting the edge between the 10 and the surrounding ground, and a drawing step S5 for pulling out the steel pipe pile 10.
In this example, a pile cueing step S1 for confirming the pile position is further provided before the insertion step S2.
The method for pulling out a steel pipe pile of the present invention has one feature in that a rotational force and a pulling force are directly applied to the steel pipe pile 10 from the tip side.

<2> Pile heading process.
The head of the steel pipe pile 10 is exposed.
Specifically, the circumference of the steel pipe pile 10 buried up to the head in the ground is dug down with a backhoe or the like, and the head of the steel pipe pile 10 is exposed about 20 cm from the ground (FIG. 5A [2]).
If the head of the steel pipe pile 10 is covered with a pile head cap, remove it.

<3> Insertion process.
The connecting rod 20 is inserted into the pipe of the pile body 11 from the head of the steel pipe pile 10.
Specifically, the head of the connecting rod 20 is set on the leader of the construction machine placed on the ground, the connecting rod 20 is inserted into the pipe of the pile body 11 along the leader (FIG. 5A [3]), and the connecting end 22 is inserted. It is made to reach the inside of the engaging space 12c of the engaging portion 12.
At this time, the tip of the first portion 22b in the connecting means 22a (keyway) of the connecting end 22 is aligned with the engaging means 12a (block body) in the engaging portion 12, and the engaging means 12a is placed in the first portion 22b. Move relative to the tip of.

<3.1> Breakage of the flow path pipe.
In this example, the flow path pipe 13 that crosses the engaging space 12c is provided in the engaging portion 12.
When the connecting end 22 is inserted into the engaging space 12c, the tip of the connecting end 22 pushes the flow path pipe 13 toward the closed end 12b. As a result, the flow path pipe 13 is sheared and the pipe wall of the flow path pipe 13 is broken (FIG. 3).
Due to the breakage of the flow path pipe 13, the engagement space 12c communicates with the outside of the engaging portion 12 via the flow path pipe 13 to form a flow path capable of ejecting the filler A and the excavated water B to the outside of the pipe.

<4> Connection process.
The connecting end 22 of the connecting rod 20 is engaged with and connected to the engaging portion 12 of the steel pipe pile 10.
Specifically, in the insertion step S2, the connecting end 22 is rotated around the axis of the connecting rod 20 by the construction machine in a state where the engaging means 12a (block body) is located on the tip end side of the first portion 22b. (FIG. 5A [4]).
Then, the engaging means 12a relatively moves in the second portion 22c of the connecting means 22a along the circumferential direction of the connecting end 22, and abuts on the tip of the second portion 22c.
As a result, the connecting end 22 is connected to the engaging portion 12, and the rotational force and the pulling force of the connecting rod 20 can be transmitted to the steel pipe pile 10.

<5> Edge cutting process.
Cut the edge between the peripheral surface of the steel pipe pile 10 and the surrounding ground.
In this example, in the edge cutting step S4, the excavated water B is previously sent to the ground around the engaging portion 12 (FIG. 5B [5]).
Specifically, the excavated water B is pumped from the ground to the inside of the engaging space 12c via the liquid feeding path 23 of the connecting rod 20. The excavated water B enters the ground around the engaging portion 12 from the engaging space 12c through the flow path in the pipe formed by the breakage of the flow path pipe 13.
By infiltrating the excavated water B between the engaging portion 12 and the ground, the peripheral surface of the engaging portion 12 is partially cut off from the ground, and the rotational torque of the connecting rod 20 is reduced.
Subsequently, a construction machine applies a rotational force around the axis to the engaging portion 12 via the connecting rod 20 to cut the edge between the steel pipe pile 10 and the surrounding ground (FIG. 5B [6]).
In the method of removing the steel pipe pile of the present invention, the edge of the steel pipe pile 10 and the ground is cut in advance to release the restraint by the ground, so that the steel pipe pile 10 is pulled out with a small force in the subsequent pulling step S5. Will be possible.

<6> Extraction process.
Pull out the steel pipe pile 10.
Specifically, the connecting rod 20 is pulled upward along the leader of the construction machine while applying a rotational force around the axis from the construction machine to the engaging portion 12 of the steel pipe pile 10 via the connecting rod 20 (FIG. 5B). [7]).
The drawing of the steel pipe pile 10 is not limited to the method of applying a rotational force, and the steel pipe pile 10 may be pulled out in a straight line without giving rotation.
In the method of pulling out the steel pipe pile of the present invention, since the steel pipe pile 10 is pulled out from the tip side, the pulling force acts as a compressive force on the joint portion of the steel pipe pile 10, and stress in the tensile direction is not applied to the joint portion. Therefore, the joint portion is not easily damaged.
Further, even if the joint portion is damaged, since the connecting rod 20 is connected to the tip of the steel pipe pile 10, only the tip of the steel pipe pile 10 does not remain in the ground.

<6.1> Filling of filler.
In this example, the steel pipe pile 10 is pulled out from the ground by the construction machine 30, and at the same time, the filler A is filled into the trace hole after the pulling out (FIG. 5B [7]).
Specifically, the filler A is sent from the ground through the liquid feeding path 23 of the connecting rod 20 into the engaging space 12c of the engaging portion 12, and the filler A is sent from the engaging space 12c via the flow path pipe 13. , Filling material A is discharged to fill the inside of the trace hole.
In this example, a cement-bentonite-based self-hardening mixed material is used as the filler A. The cement-bentonite-based self-hardening mixed material is a mixed material in which water, cement, and bentonite are blended, and has extremely high fluidity and has excellent filling property and water blocking property in the ground. Furthermore, the strength after solidification can be easily changed in a wide range by adjusting the composition.
However, the filler A is not limited to this, and for example, fluidized soil, cement paste whose strength has been appropriately adjusted, a slurry whose flow has been adjusted by adding a thickener to sand, or the like may be adopted.
If the strength of the filler A is made extremely larger than the ground strength, it may become an underground obstacle in the future, so it is set to be slightly higher than the ground strength.
By hardening the filler A in the trace hole, the trace hole is completely closed and the ground is restored to its original state (FIG. 5B [8]).

[Example of engaging means having a screwing structure]
In the first embodiment, a combination of a protrusion and a keyway is adopted as the engaging means 12a of the engaging portion 12 and the connecting means 22a of the connecting end 22.
In this example, as the engaging means 12a and the connecting means 22a, a screwing structure is adopted by a combination of a female screw groove carved on the inner surface of the engaging portion 12 and a male screw groove carved on the outer periphery of the connecting end 22. do.
In the case of this example, in the connecting step S3, by rotating the connecting rod 20 around the axis, the male thread groove of the connecting means 22a is screwed into the female thread groove of the engaging means 12a to connect the two.

[Example of steel pipe pile with open tip]
In the first embodiment, a cap-shaped member having a closed end 12b at the tip is adopted as the engaging portion 12 of the steel pipe pile 10, but an open tip type may be used without the closed end 12b.
In the case of this example, when the steel pipe pile 10 is penetrated, earth and sand intrude from the tip of the engaging portion 12 to block the inside of the steel pipe pile 10.
Therefore, at the time of pulling out, in the insertion step S2, the excavated water B is sprayed from the tip of the connecting end 22 via the liquid feeding path 23, and the connecting rod 20 is inserted while scouring the earth and sand in the pipe. The washed earth and sand become a slurry and are sequentially removed from the head of the steel pipe pile 10 to the outside.
In this example, in order to prevent the backflow of the excavated water B, it is desirable to provide a check valve at the tip of the liquid feed passage 23.
In the edge cutting step S4, the steel pipe pile 10 is rotated to cut the edge with the ground while injecting the excavated water B from the tip of the engaging portion 12 to the ground around the engaging portion 12.
In the drawing step S5, the excavated water B is switched to the filler A, and the filler A is discharged from the tip of the engaging portion 12 into the trace hole for filling.
In this example, even when groundwater has infiltrated into the pipe of the steel pipe pile 10, the filler A can be directly filled from the bottom of the hole to replace the groundwater, so that the filler A is diluted or separated. Hateful.

[Example of filling the filler after drawing]
In the first embodiment, in the drawing step S5, the filler A is filled at the same time as the drawing of the steel pipe pile 10, but it may be filled after the drawing of the steel pipe pile 10.
Specifically, after the drawing step S5 is completed, the filling material A is inserted from the ground into the trace hole after the steel pipe pile 10 is pulled out to reach the bottom of the hole, and the filling material A is discharged from the tip of the injection pipe. Fill from the bottom of the hole. After filling, the injection tube is pulled up from the trace hole and collected.

[Example of applying striking force to the connecting rod]
In this example, a striking force is applied to the connecting rod 20 in the edge cutting step S4.
Specifically, a striking force is applied from the construction machine to the head of the connecting rod 20 together with the water supply of the excavated water B and the rotation of the connecting rod 20.
The striking force applied to the head of the connecting rod 20 is transmitted to the connecting end 22 of the connecting rod 20 via the inside of the pipe of the pile body 11, and acts directly on the tip of the steel pipe pile 10.
Since the rod body 21 of the connecting rod 20 is not restrained by the steel pipe pile 10 or the surrounding ground, in this example, the striking force received from the construction machine is directly transmitted to the tip of the steel pipe pile 10 without being attenuated. be able to. Therefore, it is possible to efficiently cut the edges.

1 Connecting structure 10 Steel pipe pile 11 Pile body 12 Engaging part 12a Engaging means 12b Blocked end 12c Engaging space 13 Flow pipe 20 Connecting rod 21 Rod body 22 Connecting end 22a Connecting means 22b First part 22c Second part 23 Liquid feed Road 23a Check valve 30 Construction machine A Filling material B Washing liquid

Claims (4)

A steel pipe pile that can be connected to a connecting rod for pulling out a steel pipe pile inserted in the pipe when buried in the ground.
Hollow pile body and
With an engaging portion provided at the tip of the pile body,
The engaging portion has an engaging space communicating with the inside of the pipe of the pile body and an engaging means provided on the inner surface of the engaging portion.
The engaging means has a structure capable of engaging with the connecting end by inserting the connecting end of the tip of the connecting rod into the engaging space and rotating the engaging end.
The engaging portion has a hollow flow path pipe that communicates the side surface of the engaging portion in a direction orthogonal to the longitudinal direction of the pile body and crosses the engaging space.
The flow path pipe is located at a height at which the connecting end of the connecting rod is pushed toward the tip end side of the engaging portion by the connecting end when the connecting end is engaged with the engaging portion.
It is characterized in that the rotational force and the pulling force of the connecting rod can be transmitted through the engagement between the engaging portion and the connecting end.
Steel pipe pile. The engaging means is a protrusion or a keyway, and a keyway or a protrusion is provided on the outer periphery of the connecting end of the connecting rod, and the keyway of the engaging means or the keyway of the connecting end is provided. , The first portion that allows the relative movement of the protrusion of the connection end or the protrusion of the engagement means due to the insertion of the connection end into the engagement space, and the engagement of the connection end that is continuous with the first portion. The steel pipe pile according to claim 1, wherein the steel pipe pile has a second portion that allows relative movement of the protrusion of the connecting end or the protrusion of the engaging means with rotation in the joint space. The method for pulling out a steel pipe pile according to claim 1 or 2 , wherein a construction machine placed on the ground and a connecting rod connected to the construction machine are used to pull out the steel pipe pile buried in the ground.
The connecting rod includes a hollow rod body that can be inserted into the pipe from the head of the steel pipe pile, and a connecting end attached to the tip of the rod body, and the connecting end is placed on the outer periphery of the connecting end. It has a structure that can be engaged with the engaging portion by inserting it into the engaging portion at the tip of the steel pipe pile and rotating it.
An insertion step of inserting the connecting rod into the pipe of the pile body from the head of the steel pipe pile and inserting the connecting end into the engaging portion.
A connecting step of applying a rotational force around an axis to the connecting rod by the construction machine to engage the connecting end with the engaging portion to connect the connecting rod.
An edge cutting step of applying a rotational force around an axis to the engaging portion via the connecting rod by the construction machine to cut the edge between the steel pipe pile and the surrounding ground.
It is characterized by comprising a pulling step of pulling out the steel pipe pile while applying a rotational force and a pulling force around an axis to the steel pipe pile via the connecting rod by the construction machine.
How to pull out steel pipe piles. The method for pulling out a steel pipe pile according to claim 3 , wherein in the edge cutting step, excavated water is sent from the engaging portion to the ground around the engaging portion via the inside of the pipe of the connecting rod.

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