JP4412168B2 - Steel pipe pile construction method and buckling prevention jig - Google Patents

Description

The present invention relates to a construction method and buckling preventing jig of the steel pipe pile penetrating the steel pipe pile formed in the intermediate air-shape in the ground.

  Conventionally, as a method of constructing piles that can be constructed with low vibration, low noise, and no soil removal, while applying a rotational force to piles formed in a hollow shape, such as steel pipe piles, using construction machines installed on the ground The construction method of the pile which embeds this pile in the ground and embeds is used. As a construction method of such a pile, for example, there are those described in Patent Document 1 and Patent Document 2.

  The pile used for the construction method of the pile described in Patent Document 1 is a cylindrical pile, a bottom plate provided with a drilling blade and fixed to the lower end surface of the pile, and approximately twice the outer diameter of the pile. And a spiral wing having an outer diameter and coupled to the outer peripheral surface of the lower end side of the pile. The construction method of this pile is to press the ground against the relatively soft ground while applying rotational force to the pile, softening the earth and sand located below the pile with the excavating blade, The pile is penetrated into the ground by embedding the spiral wing into the unexcavated soil and propelling the pile into the ground using the proof strength of the soil as a reaction force. With such a pile construction method, the piles can be buried without draining the earth and sand to the ground because excavating the softened earth and sand on the outer periphery of the pile is performed under the pile. . Moreover, the construction of the pile is facilitated by the spiral wing coupled to the outer peripheral surface on the lower end side of the pile, and the pile after construction can obtain a large tip support force according to the area of the spiral wing.

  Moreover, the pile used for the construction method of the pile described in patent document 2 is formed from the cylindrical pile and the screw-shaped obstruction | occlusion board provided in the inside of a pile. This pile construction method is to press the pile into the ground while rotating the pile in the propulsion direction of the closing plate, and after the lower end of the pile reaches the ground support layer, press the pile into the ground while inverting the pile. Thus, the pile is embedded in the ground while forming a compacted soil inside the lower end of the pile. If it is the construction method of such a pile, since the front-end | tip obstruction | occlusion effect of a pile will be accelerated | stimulated by the compacted soil formed in the lower end inside a pile, the front-end | tip support force which the pile after construction will increase will increase.

Moreover, as a pile embed | buried in the ground, giving rotational force to a pile using the construction machine installed on the ground, in addition to the pile used for the construction method of a pile mentioned above, it describes in patent document 3, for example There is a pile. This pile is formed by combining a plurality of single pipes formed by cylindrical steel pipes along the respective axial directions, and at least one reinforcing member is installed by welding or the like inside each single pipe. ing. If it is such a pile, since the buckling length which arises in a pile is shortened by a reinforcing member, it becomes possible to improve the buckling strength which a pile has, and it can prevent buckling which arises at the time of penetration of a pile. It becomes possible.
Japanese Patent Publication No. 02-62648 Japanese Patent No. 2516475 JP 2004-190268 A

  However, in the construction method of the pile described in Patent Document 1, since the bottom plate is fixed at the lower end of the pile, the earth pressure acting by the earth and sand softened below the pile and pushed out to the outer peripheral surface of the pile, There is a risk of buckling of the pile. For this reason, in order to prevent the buckling which arises in a pile, it is necessary to increase the board thickness of a pile rather than the board thickness required for support of a structure, and the manufacturing cost of a pile will increase.

  Moreover, in the construction method of the pile described in patent document 2, since the screw-shaped obstruction board is provided only in the inside of a pile, even if it gives rotational force to a pile, in order to penetrate a pile into the ground It is difficult to obtain the necessary driving force. In particular, after earth and sand enters the pile and the inside of the pile becomes closed, the method of obtaining the propulsive force of the pile disappears because the closing plate is buried in the earth and sand, and the pile to the hard ground is lost. It becomes difficult to penetrate.

Moreover, in the pile described in patent document 3, since the reinforcement member is installed in the inside of a pile by welding etc., the installation operation of a reinforcement member becomes difficult and there exists a problem that the manufacturing cost of a pile will increase.
Here, the earth pressure acting upon the penetration of the pile can be reduced to some extent by moving the earth and sand on the outer peripheral surface of the pile while softening, such as moving the pile up and down at the time of penetration. However, if the pile is moved up and down during the penetration of the pile, the construction work of the pile will be prolonged. In addition, the degree to which the soil is softened by moving the pile up and down is uncertain because it is greatly affected by the skill level of the operator who operates the construction machine. Furthermore, even if the earth and sand on the outer peripheral surface of the pile are softened, depending on the ground, the softened state of the earth and sand may be recovered in a short time. Moreover, since the earth and sand in the outer peripheral surface of a pile will be discharged | emitted to the ground if a pile is moved up and down at the time of penetration of a pile, the construction work of a pile without an undrained soil cannot be performed. Furthermore, in the method of raising and lowering the pile at the time of the penetration of the pile, the ground on the circumferential surface of the pile is disturbed, and the circumferential friction may be reduced.

  The present invention has been made paying attention to the above-described problems, and can prevent buckling caused by an external force such as earth pressure, torque, pushing force and pulling force acting on the pile at the time of penetration. An object of the present invention is to provide a pile construction method and a buckling prevention jig capable of improving the penetration performance of the pile and the tip supporting force of the pile after construction.

In order to solve the above-mentioned problem, the invention described in claim 1 of the present invention is a construction method of a steel pipe pile in which a hollow steel pipe pile is buried in the ground,
While pressing the inner circumferential surface of the position is likely to buckling occurs in the steel pipe pile of the inner peripheral surface of the steel pipe pile in the outer diameter direction of the steel pipe pile, penetrate the steel pipe pile into the ground, its penetration It is characterized by preventing buckling sometimes occurring in the steel pipe pile .
According to the present invention, by pressing the inner peripheral surface of the steel pipe pile in the outer diameter direction, the steel pipe pile can be penetrated into the ground while preventing buckling caused by earth pressure acting when the steel pipe pile is penetrated. It becomes possible .

Next, the invention described in claim 2, an invention of claim 1, and rotating the steel pipe pile having a wing-like plate at the tip portion or the outer peripheral, the steel pipe pile by a screw action of the wing-like plate It is characterized by penetrating into the ground.
According to the present invention, the wing-like plate which is coupled to the distal end or the outer periphery of the steel pipe pile, improved driving force for underground steel pipe pile, the tip having the penetration performance and steel pipe pile after the construction of the ground of the steel pipe pile Supporting force is improved.

Next, the invention described in claim 3 is inserted into a hollow steel pipe pile, and buckling may occur in the steel pipe pile when the steel pipe pile penetrates into the ground out of the inner peripheral surface of the steel pipe pile. the inner peripheral surface of the sex and the elevated position, a buckling preventing jig for pressing the outer diameter direction of the steel pipe pile,
A bag body that is inserted into the steel pipe pile and expands by injecting a fluid therein, and a fluid injection means for injecting a fluid into the bag body are provided. .
According to the present invention, fluid is injected into the inside of the bag body inserted into the steel pipe pile to inflate the bag body, and the inner peripheral surface of the steel pipe pile is pressed in the outer diameter direction by the fluid pressure of the expanded bag body. By doing so, it becomes possible to prevent buckling caused by earth pressure or the like acting when the steel pipe pile is penetrated.

Next, the invention described in claim 4 is inserted into the hollow steel pipe pile, and buckling may occur in the steel pipe pile when the steel pipe pile penetrates into the ground out of the inner peripheral surface of the steel pipe pile. the inner peripheral surface of the sex and the elevated position, a buckling preventing jig for pressing the outer diameter direction of the steel pipe pile,
A pressing part that is inserted into the steel pipe pile and faces the inner peripheral surface of the steel pipe pile; and an expansion / contraction part that moves the pressing part in the radial direction of the steel pipe pile by expanding and contracting in the radial direction of the steel pipe pile; And a drive unit that expands and contracts the expansion / contraction part.
According to the present invention, inside the steel pipe pile, the inner peripheral surface of the steel pipe pile is pressed in the outer diameter direction by expanding and contracting the elastic part in the radial direction of the steel pipe pile and moving the pressing part in the radial direction of the steel pipe pile. This makes it possible to prevent buckling caused by earth pressure acting when the steel pipe pile is penetrated.

According to the present invention, by preventing the buckling occurring in the steel pipe pile by the soil pressure and the like which acts upon penetration of the steel pipe pile, with the as the plate thickness of the steel pipe pile suitable thickness, penetration of the steel pipe pile performance and after construction Since it is possible to improve the tip supporting force of the steel pipe pile, it is possible to reduce costs and improve construction efficiency.

Next, embodiments of the present invention will be described with reference to the drawings.
First, the configuration of the first embodiment of the present invention will be described with reference to FIG .
As shown in FIG. 1, the steel pipe pile 1 of the present embodiment is formed of a cylindrical steel pipe, and a pair of wing-like plates 2 are coupled to the tip of the steel pipe pile 1.

  The pair of winged plates 2 are each formed in a semicircular shape by a flat steel plate, and are combined so that a circle is formed when viewed from the axial direction of the steel pipe pile 1. It connects with the front-end | tip part of the steel pipe pile 1 so that it may block | close. The outer diameter of the circle formed by combining the pair of wing plates 2 is about 1.5 to 3 times the outer diameter of the steel pipe pile 1. The pair of wing plates 2 are coupled so as to form a predetermined inclination with respect to the central axis of the steel pipe pile 1, and the pair of wing plates 2 are coupled only in the vicinity of the center of each other.

When constructing such a steel pipe pile 1, in order to prevent buckling that occurs in the steel pipe pile 1 due to earth pressure or the like acting when the steel pipe pile 1 penetrates, construction work is performed using a buckling prevention jig. Hereinafter, the configuration of the buckling prevention jig will be described.
The buckling prevention jig includes a bag body 4 inserted into the steel pipe pile 1 and a fluid injection means 8 for injecting a fluid 6 into the bag body 4.

  The bag body 4 is formed by integrally molding an elastic material such as rubber, and has a strength that does not break even if the fluid 6 is injected into the bag body 4 to expand. Moreover, the bag body 4 is arrange | positioned so that the inner peripheral surface of the steel pipe pile 1 may be pressed in the outer-diameter direction of the steel pipe pile 1 in the inside of the steel pipe pile 1 when the fluid 6 is inject | poured and it expands inside. . Here, the position pressed in the outer diameter direction from the inner peripheral surface of the steel pipe pile 1 by the expanded bag body 4 among the inner peripheral surfaces of the steel pipe pile 1 varies depending on the plate thickness of the steel pipe pile 1 and the state of the ground. However, it is usually 4 to 5 m above the tip of the steel pipe pile 1. For example, air or water is used as the fluid 6.

  The fluid injection means 8 is formed by, for example, a pump, and adjusts the fluid pressure of the expanded bag body 4 to a predetermined pressure by adjusting the amount of the fluid 6 injected into the bag body 4. Here, although a predetermined pressure changes with the plate | board thickness of the steel pipe pile 1, the state of the ground, etc., it is normally set as the pressure of about 0.5-1.5 MPa. Further, the fluid injection means 8 has a discharge port for the fluid 6, and the discharge port for the fluid 6 communicates with the inside of the bag body 4.

Next, functions and effects of this embodiment will be described.
The construction work of the steel pipe pile 1 of this embodiment is performed according to the following procedure.
First, the steel pipe pile 1 is supported upright with respect to the ground by a base machine or the like, and the bottom surfaces of the pair of wing plates 2 are brought into contact with the ground, respectively. And while giving rotational force to the steel pipe pile 1 with an auger motor, an all-around rotating machine, etc., and applying a vertical downward pressing force with a pushing force load device as needed, the steel pipe pile 1 is grounded from the tip side. It penetrates while screwing inside.

  Moreover, while penetrating the steel pipe pile 1, the fluid 6 is inject | poured into the inside of the bag body 4 by the fluid injection | pouring means 8, and the bag body 4 is expanded. And the inner peripheral surface of the steel pipe pile 1 is uniformly pressed by the inflated bag body 4 with a predetermined pressure in the outer diameter direction of the steel pipe pile 1. At this time, the fluid injection means 8 adjusts the fluid pressure of the inflated bag body 4 to a predetermined pressure by adjusting the injection amount of the fluid 6.

  When the steel pipe pile 1 is penetrated from the tip side while being screwed into the ground, the pair of wing-like plates 2 softens the earth and sand located below the steel pipe pile 1 and pushes it out to the outer peripheral side of the steel pipe pile 1. Earth pressure acts on the outer peripheral surface of the pile 1. At this time, the inner peripheral surface of the steel pipe pile 1 is generated in the steel pipe pile 1 because it is pressed with a predetermined pressure in the outer diameter direction of the steel pipe pile 1 by the bag body 4 inflated by injecting the fluid 6 therein. Buckling is prevented.

  After the steel pipe pile 1 has been penetrated to a predetermined depth, the embedding of the steel pipe pile 1 is finished, and after a predetermined time has passed with the bag body 4 inflated, the fluid 6 injected into the bag body 4 is injected. Discharge. Here, the predetermined time is a time during which the earth pressure acting on the outer peripheral surface of the steel pipe pile 1 is lowered. In addition, as a main factor by which the earth pressure which acts on the outer peripheral surface of the steel pipe pile 1 falls, there exists a fall of the pore water pressure by the pore water contained in the ground dissipating, for example. When the fluid 6 is discharged from the inside of the bag body 4, for example, an openable / closable discharge hole may be provided below the bag body 4, and the fluid 6 may be discharged from the discharge hole. Further, the fluid injection means 8 has a configuration having a discharge port and a suction port, and the fluid 6 injected into the bag body 4 is sucked by communicating the discharge port and the suction port with the inside of the bag body 4. It is good also as a structure returned to the fluid injection | pouring means 8 from an opening | mouth.

After the fluid 6 injected into the bag body 4 is discharged, the bag body 4 is recovered from the steel pipe pile 1 and taken out to the ground, and the construction work of the steel pipe pile 1 is completed.
Therefore, according to the construction method of the steel pipe pile 1 of this embodiment, when the steel pipe pile 1 penetrates into the ground, the inner circumference of the steel pipe pile 1 is injected by the bag body 4 that is inflated by injecting the fluid 6 therein. Since the surface is pressed in the outer diameter direction of the steel pipe pile 1 with a predetermined pressure, buckling occurring in the steel pipe pile 1 is prevented. For this reason, it is not necessary to increase the plate thickness of the steel pipe pile 1 more than necessary, and the manufacturing cost of the steel pipe pile 1 can be reduced.

  Further, since the propulsion force of the steel pipe pile 1 into the ground is improved by the pair of wing-like plates 2 coupled to the tip of the steel pipe pile 1, the penetration performance of the steel pipe pile 1 into the ground is improved, and the hard ground The construction of the steel pipe pile 1 is facilitated. Moreover, since the outer diameter of the circle formed by combining the pair of winged plates 2 is about 1.5 to 3 times the outer diameter of the steel pipe pile 1, the steel pipe pile 1 after construction has a high tip support force; Become.

Furthermore, after construction of the steel pipe pile 1, the fluid 6 is discharged from the inside of the bag body 4, and the bag body 4 is recovered from the inside of the steel pipe pile 1 and taken out to the ground. This makes it possible to reduce work costs.
In addition, waste that does not adversely affect the environment, such as residual soil at the construction site, can be introduced into the steel pipe pile 1 after the bag body 4 has been collected. Work can be omitted, and work costs can be reduced and work efficiency can be improved. Moreover, instead of putting waste etc. into the inside of the steel pipe pile 1, if concrete is cast, for example, the rigidity of the steel pipe pile 1 will be improved.

Also, depending on the bag 4 inflated by pressing with a predetermined pressure an inner peripheral surface in the outer diameter direction of the steel pipe pile 1, as a result of the rigidity of the steel pipe pile 1 is increased, the steel pipe pile 1 during construction of the steel pipe pile 1 It is possible to prevent the steel pipe pile 1 from being damaged by external forces such as torque, pushing force, pulling force, etc.
Moreover, in order to discharge | emit the fluid 6 inject | poured into the inside of the bag body 4 after the predetermined time passes in the state which penetrated the steel pipe pile 1 to the predetermined depth, and expanded the bag body 4, this predetermined | prescribed It is possible to perform construction work without hindering the whole work process by setting the time to be time for other work such as preparation for construction of the steel pipe pile 1 to be constructed next in the whole work process. Therefore, the construction efficiency is improved.

  In addition, in the construction method of the steel pipe pile 1 of this embodiment, although the bag body 4 was formed with the elastic material integrally molded, it is not limited to this, For example, an annular steel material inside the bag body 4 May be arranged to form the bag body 4. In this case, the strength of the bag body 4 is improved and the number of times that the bag body 4 can be reused is increased, and the cost can be reduced.

  Moreover, in the construction method of the steel pipe pile 1 of this embodiment, after burying of the steel pipe pile 1 is complete | finished and predetermined time passes in the state which expanded the bag body 4, it is inject | poured inside the bag body 4. FIG. Although the fluid 6 was discharged | emitted and the bag body 4 was collect | recovered from the inside of the steel pipe pile 1, it is not limited to this. That is, when the bag body 4 is not reused, the bag body 4 may be left inside the steel pipe pile 1 while the fluid 6 is injected and inflated, and the fluid injected into the inside is left. You may leave the bag body 4 which discharged | emitted 6 in the inside of the steel pipe pile 1. FIG. Moreover, as the fluid 6, for example, a fluid that hardens after a predetermined time such as concrete before hardening, and after the concrete used as the fluid 6 is hardened, the rigidity of the steel pipe pile 1 is improved by the hardened concrete. Also good.

Furthermore, in the construction method of the steel pipe pile 1 of the present embodiment, the bag body 4 is arranged only at one place inside the steel pipe pile 1, but the present invention is not limited to this, and a plurality of bag bodies 4 are used. The bag body 4 may be arranged at a plurality of locations inside the steel pipe pile 1.
Moreover, in the construction method of the steel pipe pile 1 of this embodiment, while penetrating the steel pipe pile 1, the fluid 6 was inject | poured into the inside of the bag body 4 by the fluid injection | pouring means 8, and the bag body 4 was expanded, However, the bag body 4 may be expanded at a depth at which an external force such as earth pressure starts to act on the steel pipe pile 1.

Moreover, in the construction method of the steel pipe pile 1 of this embodiment, although the steel pipe pile 1 was formed with the cylindrical-shaped steel pipe, it is not limited to this, If a hollow shape is used, for example, a radial cross section will be a polygon. The steel pipe pile 1 may be formed of the steel pipe.
Moreover, in the steel pipe pile 1 used by this embodiment, although the front end side opening part of the steel pipe pile 1 was obstruct | occluded with a pair of winged board 2, it is not limited to this, The front end of the steel pipe pile 1 is made into an open end. Also good. In this case, for example, by disposing a disk or the like inside the steel pipe pile 1, it is preferable to prevent the soil from rising inside the steel pipe pile 1 and facilitate the arrangement and recovery of the bag body 4.

Moreover, in the steel pipe pile 1 used by this embodiment, although a pair of winged board 2 was formed in flat form together, it is not limited to this. That is, if it is the shape which the propulsion force to the underground of the steel pipe pile 1 improves, for example, a spiral shape may be sufficient.
Moreover, in the steel pipe pile 1 used by this embodiment, although the pair of wing-like board 2 was couple | bonded with the front-end | tip part of the steel pipe pile 1, the front end side opening part of the steel pipe pile 1 was obstruct | occluded, It is not limited to this Instead, the closing member for closing the tip of the steel pipe pile 1 and the winged plate 2 may be configured separately. In this case, the position where the wing plate 2 is coupled is not limited to the tip of the steel pipe pile 1, and the wing plate 2 can be coupled to an arbitrary position on the outer periphery of the steel tube pile 1. Moreover, the rigidity of the steel pipe pile 1 in the position where the wing-like plate 2 is joined is improved by joining the wing-like plate 2 to the outer periphery of the steel pipe pile 1.

  Moreover, in the steel pipe pile 1 used by this embodiment, although the outer diameter of the circle formed combining the pair of winged plates 2 was set to about 1.5 to 3 times the outer diameter of the steel pipe pile 1, it is limited to this. Is not to be done. In addition, when the outer diameter of the circle formed by combining the pair of winged plates 2 increases, the amount of earth and sand that softens below the steel pipe pile 1 increases, so the earth pressure acting on the outer peripheral surface of the steel pipe pile 1 decreases. For this reason, for example, if the construction work of the steel pipe pile 1 is performed in a place where the ground state is uniform, the predetermined pressure is changed according to the size of the outer diameter of the circle formed by combining the pair of wing plates 2. May be.

Moreover, in the steel pipe pile 1 used by this embodiment, although a pair of wing | blade shape board 2 was couple | bonded only with the front-end | tip part of the steel pipe pile 1, it is not limited to this, A pair of wing | blade shape is added to the front-end | tip part of the steel pipe pile 1. While combining the board 2, it is good also as a structure which couple | bonds the wing-like board 2 of the shape which the propulsion force to the underground of the steel pipe pile 1 improves in the arbitrary positions of the outer periphery of the steel pipe pile 1. FIG.
Moreover, in the steel pipe pile 1 used by this embodiment, although a pair of winged board 2 was couple | bonded with the front-end | tip part of the steel pipe pile 1, it is not limited to this, As a structure which does not have the winged board 2 Good.

Moreover, the buckling prevention jig | tool of this embodiment is the steel pipe which penetrates, while screwing the steel pipe pile 1 in the ground from the front end side by giving a rotational force with respect to the steel pipe pile 1 and giving a vertical downward pressing force. Although it used for the construction method of the pile 1, it is not limited to this. That is, for example, by applying a vertical downward pressing force to the steel pipe pile 1 without applying a rotational force, a steel pipe pile construction method (blow method) that penetrates the steel pipe pile 1 into the ground from the tip side, After excavating to a predetermined depth in advance, the construction method (embedding method) for embedding the steel pipe pile 1, the construction method (embedding method) for embedding the steel pipe pile 1 while excavating the hollow part of the steel pipe pile 1, etc. Also good.

Next, the configuration of the second embodiment of the present invention will be described with reference to FIG. In addition, about the structure similar to 1st embodiment mentioned above, the same code | symbol is attached | subjected and demonstrated.
As shown in FIG. 2, the steel pipe pile 1 of this embodiment differs in the structure of the buckling prevention jig from 1st embodiment mentioned above. That is, instead of the buckling prevention jig in the first embodiment including the bag body 4 and the fluid injection means 8, the buckling prevention jig in the present embodiment includes a pressing portion 10, an expansion and contraction portion 12, and A drive unit 14 is provided.

  The pressing part 10 is inserted into the steel pipe pile 1 and is formed of a steel plate curved into a shape corresponding to the inner peripheral surface of the steel pipe pile 1. An elastic material such as is provided. Moreover, the surface facing the inner peripheral surface of the steel pipe pile 1 of the pressing part 10 is disposed inside the steel pipe pile 1 so as to press the inner peripheral surface of the steel pipe pile 1.

The expansion / contraction part 12 has a mechanism that expands and contracts in the radial direction of the steel pipe pile 1, the pressing part 10 is connected to the distal end part, and the base end part is connected to the drive part 14. In addition, a plurality of expansion / contraction parts 12 are connected to one drive unit 14, and each expansion / contraction part 12 expands and contracts in different directions. In the present embodiment, the case where there are four stretchable parts 12 is described as an example, but the number of stretchable parts 12 is not limited to this. Moreover, it is good also as a structure which connected the one expansion-contraction part 12 to the one drive part 14. FIG.
The drive unit 14 is formed by mechanical means such as a hydraulic actuator, and expands and contracts the expansion / contraction part 12 in the radial direction of the steel pipe pile 1. Moreover, the drive part 14 adjusts the expansion-contraction amount of the expansion-contraction part 12 so that the pressing force to the internal peripheral surface of the steel pipe pile 1 by the press part 10 turns into a predetermined pressure.
Other configurations are the same as those of the first embodiment described above.

Next, with reference to FIG.3 and FIG.4, the effect | action and effect, etc. of this embodiment are demonstrated. Since the other operations and effects other than the operation and effects of the buckling prevention jig are the same as those in the first embodiment described above, detailed description thereof will be omitted.
The construction work of the steel pipe pile 1 of this embodiment is performed according to the following procedure.
The steel pipe pile 1 is penetrated by the same procedure as in the first embodiment, and the stretchable part 12 is extended in the outer diameter direction of the steel pipe pile 1 as shown in FIG. In FIG. 3, the expansion / contraction part 12 is extended in the outer diameter direction of the steel pipe pile 1, and the inner peripheral surface of the steel pipe pile 1 is extended in the outer diameter direction by a surface facing the inner peripheral surface of the steel pipe pile 1 of the pressing part 10. It is the figure which looked at the pressed state from the lower end side of the steel pipe pile 1. FIG.

At this time, the expansion / contraction amount of the expansion / contraction part 12 is adjusted by the drive part 14 so that the pressing force to the inner peripheral surface of the steel pipe pile 1 by the pressing part 10 becomes a predetermined pressure. And the inner peripheral surface of the steel pipe pile 1 is pressed by the press part 10 in the outer-diameter direction of the steel pipe pile 1 with a predetermined pressure.
When the steel pipe pile 1 is penetrated from the lower end side while being screwed into the ground, the pair of wing-like plates 2 softens the earth and sand located below the steel pipe pile 1 and pushes it out to the outer peripheral side of the steel pipe pile 1. Earth pressure acts on the outer peripheral surface of the pile 1. At this time, since the inner peripheral surface of the steel pipe pile 1 is pressed with a predetermined pressure in the outer diameter direction of the steel pipe pile 1 by the surface facing the inner peripheral surface of the steel pipe pile 1 of the pressing portion 10, the steel pipe pile 1 The buckling that occurs in is prevented.

After the steel pipe pile 1 has been penetrated to a predetermined depth, the embedding of the steel pipe pile 1 is finished, and after a predetermined time has passed with the stretchable part 12 extended, the stretchable part 12 is connected to the steel pipe pile 1 as shown in FIG. The pressing portion 10 is separated from the inner peripheral surface of the steel pipe pile 1 by contracting in the direction of the central axis of the steel pipe pile 1. FIG. 4 is a view of the state in which the stretchable portion 12 is contracted in the central axis direction of the steel pipe pile 1 as viewed from the lower end side of the steel pipe pile 1.
After the expansion / contraction part 12 is contracted, the pressing part 10, the expansion / contraction part 12 and the drive part 14 are collected from the inside of the steel pipe pile 1 and taken out to the ground, and the construction work of the steel pipe pile 1 is completed.

Therefore, according to the construction method of the steel pipe pile 1 of this embodiment, when the steel pipe pile 1 penetrates into the ground, the inner peripheral surface of the steel pipe pile 1 is predetermined in the outer diameter direction of the steel pipe pile 1 by the pressing portion 10. Therefore, buckling occurring in the steel pipe pile 1 is prevented. For this reason, it is not necessary to increase the plate | board thickness of the steel pipe pile 1 more than necessary in order to construct the steel pipe pile 1, and it becomes possible to reduce the manufacturing cost of the steel pipe pile 1. FIG.
Further, after the construction of the steel pipe pile 1, the expansion / contraction part 12 is contracted, and the pressing part 10, the expansion / contraction part 12 and the drive part 14 are recovered from the inside of the steel pipe pile 1, so that a buckling prevention jig provided with these is provided. It can be reused, and the work cost can be reduced.

In addition, in the construction method of the steel pipe pile 1 of this embodiment, the expansion part 12 is extended in the outer diameter direction of the steel pipe pile 1, and the inner peripheral surface of the steel pipe pile 1 is pressed with a predetermined pressure by the pressing part 10. Although configured, it is not limited to this. In other words, any structure may be used as long as the inner peripheral surface of the steel pipe pile 1 is pressed with a predetermined pressure by mechanical means. For example, a structure such as a pantograph may be used.
Moreover, in the construction method of the steel pipe pile 1 of this embodiment, although it was set as the structure which provided the buckling prevention jig with the press part 10 only one step, it is not limited to this, The press part 10 is the steel pipe pile 1 A plurality of cuts may be provided in the depth direction or continuously.
Other actions and effects are the same as those of the first embodiment described above.

FIG. 5 shows the relationship between the N value and the depth of the ground. As shown in FIG. 5, the N value rises rapidly from the vicinity where the depth of the ground is 16 m, and is a large value until the depth of the ground becomes 20 m. It drops from around 22m. Thus, in the range where the N value near the ground depth of 16 m to 22 m is large, the steel pipe pile is likely to buckle. Here, the depth of ground of sharply elevated N values, because the tip of the steel pipe pile is a position of about 4~5m about upwardly, the inner peripheral surface of the steel pipe pile at this position in the outer diameter direction of the steel pipe pile It was confirmed that it is preferable to arrange a buckling prevention jig so as to press at a predetermined pressure in order to prevent buckling occurring in the steel pipe pile.

  Here, in the example of the present invention shown in FIG. 6 (a), the steel pipe pile 1 sits on the steel pipe pile 1 in the position of the N-value ground that has risen rapidly, that is, the inner peripheral surface of the steel pipe pile 1. The bag body 4 is arranged so as to press the inner peripheral surface at a position where the possibility of bending is high. And by the bag body 4 which inject | poured the fluid 6 inside and expanded, the inner peripheral surface of the position where possibility that buckling will arise in the steel pipe pile 1 among the inner peripheral surfaces of the steel pipe pile 1 is made into the steel pipe pile 1 of. It is pressed with a predetermined pressure in the outer diameter direction. Therefore, it is possible to prevent buckling occurring in the steel pipe pile 1 without increasing the plate thickness of the steel pipe pile 1.

Further, in the conventional example shown in FIG. 6B, buckling that occurs in the steel pipe pile 1 is prevented by increasing the plate thickness of the steel pipe pile 1.
Here, in the ground in the state as shown in FIG. 5, the plate thickness of the steel pipe pile 1 necessary for supporting the structure is 14 mm. And in the conventional example, the buckling which arises in the steel pipe pile 1 is prevented by increasing the plate thickness of the steel pipe pile 1 to 18 mm, but in the present invention example, the plate thickness of the steel pipe pile 1 is kept at 14 mm. The buckling which arises in the steel pipe pile 1 is prevented. Therefore, in the example of this invention, it was possible to prevent buckling which arises in the steel pipe pile 1 without increasing the plate | board thickness of the steel pipe pile 1, and it was confirmed that the manufacturing cost of the steel pipe pile 1 can be reduced. .

It is a figure which shows the structure of 1st embodiment of this invention. It is a figure which shows the structure of 2nd embodiment of this invention. It is a figure which shows the structure of 2nd embodiment of this invention. It is a figure which shows the structure of 2nd embodiment of this invention. It is a figure which shows the relationship between N value of a ground, and depth. It is a comparison figure of the example of the present invention and a conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steel pipe pile 2 Wing-like board 4 Bag body 6 Fluid 8 Fluid injection | pouring means 10 Press part 12 Telescopic part 14 Drive part

Claims (4)

A steel pipe pile construction method for burying a hollow steel pipe pile in the ground,
While pressing the inner peripheral surface of the inner peripheral surface of the steel pipe pile in the outer diameter direction of the steel pipe pile, the steel pipe pile penetrates into the ground, and the penetration A construction method of a steel pipe pile characterized by preventing buckling that sometimes occurs in the steel pipe pile.   The construction method of the steel pipe pile according to claim 1, wherein the steel pipe pile having a winged plate at a tip end or an outer periphery is rotated, and the steel pipe pile is penetrated into the ground by a screw action of the winged plate. Is inserted into the steel pipe pile hollow, the inner circumferential surface of the penetration time of likely positions buckling occurs in the steel pipe pile into the ground of the steel pipe pile of the inner peripheral surface of the steel pipe pile, the steel pipe A buckling prevention jig that presses in the outer diameter direction of the pile,
Buckling prevention comprising: a bag body inserted into the steel pipe pile and inflated by injecting a fluid therein; and a fluid injection means for injecting a fluid into the bag body jig. Is inserted into the steel pipe pile hollow, the inner circumferential surface of the penetration time of likely positions buckling occurs in the steel pipe pile into the ground of the steel pipe pile of the inner peripheral surface of the steel pipe pile, the steel pipe A buckling prevention jig that presses in the outer diameter direction of the pile,
A pressing part that is inserted into the steel pipe pile and faces the inner peripheral surface of the steel pipe pile; and an expansion / contraction part that moves the pressing part in the radial direction of the steel pipe pile by expanding and contracting in the radial direction of the steel pipe pile; A buckling prevention jig comprising: a drive unit that expands and contracts the expansion and contraction unit.

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