JP2016089609A - Steel pipe pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steel pipe pile capable of increasing a horizontal resistance force, a pull-out resistance force and a push-in resistance force by a simple structure.SOLUTION: A steel pipe pile is made of a hollow steel pipe. The steel pipe pile makes a foundation pile structure constructed in the ground by imparting a push-in force to the steel pipe to drive it into the ground. In the steel pipe, a plurality of slits with predetermined length are formed in an axial direction. In a part in which the slits are formed, an outside diameter of the steel pipe is displaced.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a steel pipe pile as a foundation for installing a structure such as a solar panel, and more particularly to a steel pipe pile that can increase horizontal resistance, pull-out resistance, and indentation resistance with a simple structure.

In order to strengthen the foundation of the building and the ground, steel pipe piles are rotated and embedded in the ground. In general, it is necessary to drive a very long steel pipe pile in order to ensure the specified horizontal resistance, pulling resistance and indentation resistance of the steel pipe pile. In this case, the workability is poor and economically disadvantageous. There is a problem with.
Therefore, Patent Document 1 discloses a foundation pile in which spiral blades screwed into the ground are provided on the outer peripheral surface of a portion that enters the ground in order to improve horizontal resistance, pulling resistance, and pushing resistance. .

JP 2013-204227 A

However, in the case of the foundation pile shown in Patent Document 1, in addition to requiring a dedicated heavy machine or the like for pile driving, it takes a long time to perform pile driving while rotating in the vertical direction. End up. In addition, there is a possibility that the spiral blade may be damaged in the ground during placement, and there is a problem that desired horizontal resistance force, pulling resistance force and pushing resistance force cannot be obtained.
This invention is made | formed in view of the problem which concerns, and it aims at providing the steel pipe pile which can improve a horizontal resistance force, a drawing-out resistance force, and an indentation resistance force with a simple structure.

  In order to achieve the above object, the steel pipe pile of the present invention comprises a hollow steel pipe, and applies a pushing force to the steel pipe to drive it into the ground, thereby constructing a foundation pile structure in the ground. The steel pipe is characterized in that a plurality of slits having a predetermined length are formed in the axial direction.

  Moreover, the steel pipe pile of this invention is characterized by the outer diameter of the said steel pipe being displaced by the said pushing force in the site | part in which the said slit is formed.

  The steel pipe pile of the present invention is characterized in that a plurality of the slits are provided in the vicinity of the approximate center of the steel pipe and around the circumference.

  Further, the steel pipe pile of the present invention comprises a hollow steel pipe, and a steel pipe pile for constructing a foundation pile structure in the ground by applying a pushing force to the steel pipe and driving it into the ground, the steel pipe has a cross-sectional shape. Is composed of a polygonal pile body, a tip portion coaxially with the pile body and at a position away from the lower end, and a connecting portion for connecting the pile body and the tip portion. To do.

  Moreover, the steel pipe pile of this invention is characterized by the said front-end | tip part being a structure whose cross-sectional shape is polygonal shape and shorter than the length of the said pile main body.

  Further, in the steel pipe pile of the present invention, the connecting part is formed in a thin plate shape, one end of the connecting part is fixed to the lower end of the pile body by welding, and the other end of the connecting part is used as the tip part. It is fixed by welding.

  Moreover, the steel pipe pile of this invention is characterized by the said connection part having a crease | fold in the width direction, or being bent in the shape of a dogleg with respect to the outward direction beforehand.

  Further, the steel pipe pile of the present invention is characterized in that the connecting portion is bent outwardly by a pushing force applied to the steel pipe pile.

  Furthermore, the steel pipe pile of the present invention is characterized in that a plurality of through holes for solidifying agent leakage are formed near the upper end or the lower end of the steel pipe.

According to the present invention, the steel pipe pile having the slit provided in the axial direction of the steel pipe is easily deformed larger than the outer diameter of the steel pipe when the pushing force is applied. Further, it is possible to improve the pull-out resistance force and the push-in resistance force.
In addition, in steel pipe piles where the pile body and the tip are connected by a connecting part, when a pushing force is applied, the connecting part is bent in a U shape with respect to the outer direction and is larger than the outer diameter of the pile body. As a result, the horizontal resistance force, the pullout resistance force, and the push-in resistance force can be improved.

Fig.1 (a) is a front view which shows the structure of the steel pipe pile which concerns on 1st Embodiment, FIG.1 (b) is the top view which showed the upper surface of the steel pipe pile which concerns on 1st Embodiment. . Drawing 2 (a)-(d) is a figure showing the construction method of the steel pipe pile concerning a 1st embodiment. FIG. 3 (a) is a table showing the results of a horizontal loading test performed by placing a steel pipe pile in a drilled hole with a drilling diameter of 102mm, and FIG. 3 (b) shows an excavation with a drilling diameter of 127mm. It is the table | surface which showed the result of having placed the steel pipe pile in the hole made and performing the horizontal loading test. FIG. 4 (a) is a table showing the result of a pull-out test performed by placing a steel pipe pile in a drilled hole having a drilling diameter of 102 mm, and FIG. 4 (b) is a drilling having a drilling diameter of 127 mm. It is the table | surface which showed the result of having pierced the steel pipe pile in the hole and having done the drawing test. FIG. 5 (a) is a table showing the result of the indentation test performed by placing a steel pipe pile in a drilled hole having a drilling diameter of 102mm, and FIG. 5 (b) is a drilling having a drilling diameter of 127mm. It is the table | surface which showed the result of having pushed the steel pipe pile into the hole and having performed the indentation test. Fig.6 (a) is a front view which shows the structure of the steel pipe pile which concerns on 2nd Embodiment, FIG.6 (b) is the figure which showed the upper surface of the steel pipe pile which concerns on 2nd Embodiment. It is the figure which showed the state which a part of steel pipe pile deform | transformed. FIGS. 8A to 8D are views showing a method for constructing a steel pipe pile according to the second embodiment.

<First Embodiment>
Next, the steel pipe pile which concerns on the 1st Embodiment of this invention with reference to drawings is demonstrated.
Fig.1 (a) is a front view which shows the structure of the steel pipe pile which concerns on 1st Embodiment, FIG.1 (b) is the top view which showed the upper surface of the steel pipe pile which concerns on 1st Embodiment. .
As shown in the drawing, the steel pipe pile 100 includes a tubular body 10 made of steel and formed into a hollow tubular shape, and a disk-shaped connection plate 11 integrated with the upper end of the tubular body 10 by welding or the like. A plurality of slits 12 are formed in the axial direction of the tubular body 10 and a through hole 13 is formed at a position near the top and bottom of the slit 12 in the vicinity of the approximate center of the tubular body 10.

  The connection plate 11 provided integrally with the upper end of the tubular body 10 is for fixing a structure (for example, a structure such as a solar panel) installed on the ground to the steel pipe pile 100 main body. Screws or the like are inserted into the plurality of connection holes 11a provided in the plate 11 to fix the structure.

  The slits 12 are formed in the axial direction of the tubular body 10 with 2 to 10 slits around the circumference of the tubular body 10. The number or width of the slits 12 can be changed depending on the length and diameter of the steel pipe pile 100, and can be changed depending on the strength of the ground to be buried. For example, in a weak ground, the number is increased, and in a strong ground, the number is relatively decreased to cope with the strength of the ground. When an external force is applied in the vertical direction to the steel pipe pile 100 by forming the slit 12, the portion where the slit 12 is formed cannot withstand the load and swells outward or bends. Thereby, the horizontal resistance force after pulling out the steel pipe pile 100 in the ground, the drawing-out resistance force, and the pushing-in resistance force will be improved.

Further, the shape of the deformed portion can be changed depending on the length and width of the slit 12.
When embedding the steel pipe pile 100 in the ground with a heavy machine or the like, a large compressive stress acts on the portion provided in the slit 12 by applying an external force in the vertical direction of the steel pipe pile 100. When this compressive stress acts on this part, it swells outward or bends, and this part becomes larger than the outer diameter of the tubular body 10. Thereby, the horizontal resistance force of the steel pipe pile 100, pull-out resistance force, and indentation resistance force improve.
In addition, in order to make this part easy to bulge outward or to bend easily, for example, it may be formed thinner than other parts, or a cut may be made. Further, as described above, by increasing the width of the slit 12, it is possible to make the portion to be deformed thinner and to easily swell or bend.

  The through hole 13 is a hole through which a solidifying agent such as cement milk leaks into the ground. That is, after embedding the steel pipe pile 100 in the ground, if cement milk or cement mortar is placed inside the tubular body 10 as necessary, the through hole 13 provided near the upper end and the lower end of the tubular body 10 Cement milk or cement mortar leaks into the ground and hardens later, so that the steel pipe pile 100 can be integrated with the surrounding soil, and the horizontal resistance, pull-out resistance, and indentation resistance can be improved.

Next, with reference to FIG. 2, the construction method of a steel pipe pile is demonstrated.
Fig.2 (a)-(d) is the figure which showed the construction method of the steel pipe pile.
First, a diameter larger than the diameter of the steel pipe pile 100 or a depth at which the upper end of the steel pipe pile 100 protrudes from the ground is excavated at a predetermined position on the ground with a heavy machine or the like. . Then, the drilled hole is backfilled with the mixture of cutting powder and cement (FIG. 2 (a)). The amount of backfilling powder and cement is, for example, such that 1/4 to 1/3 of the depth of the excavated hole is filled, and the amount can be changed depending on the construction situation.
Also, by filling back the excavated hole with a mixture of cutting powder and cement, the depth of the excavated holes can be made constant, and at the same time, the height of the cast steel pipe pile 100 can be made uniform. Becomes easy.

Next, the steel pipe pile 100 is driven into the excavated hole with a heavy machine or the like, and when the tip of the steel pipe pile 100 reaches a depth that is backfilled, the steel pipe pile 100 is hit. As a result, a compressive stress is applied to the portion where the slit 12 is provided, and the deformed portion becomes larger than the outer diameter of the tubular body 10 by expanding or bending outward (FIG. 2 (c)). .
Next, cement milk or cement mortar is poured from the opening at the upper end of the steel pipe pile 100 (FIG. 2 (d)). Cement milk or cement mortar to be filled leaks into a hole excavated from the through hole 13 or the slit 12 provided in the tubular body 10. Cement milk or cement mortar is poured until the inside of the tubular body 10 and the excavated hole and the periphery of the steel pipe pile 100 are filled. As a result, the steel pipe pile 100 is integrated with the surrounding soil, and the strength of the steel pipe pile 100 main body is increased by solidifying the cement milk and cement mortar filled in the tubular body 10, and the horizontal resistance force and the pulling resistance are increased. Strength and push-in resistance are improved.

Next, in order to evaluate the horizontal resistance force, the pulling resistance force, and the indentation resistance force of the steel pipe pile placed on the ground by the above construction method, a horizontal loading test, a pulling test, and an indentation test were performed.
In addition, the drilling diameters of the holes excavated in the ground when performing each test were 102 mm and 127 mm, and each test was performed after a curing period of about 3 weeks after the steel pipe pile 100 was placed on the ground.

<Horizontal loading test>
The horizontal loading test is intended to investigate the relationship between load and displacement by applying a load in the horizontal direction to the portion of the steel pipe pile protruding from the ground.
As a test method, a load is increased in a horizontal direction by a hydraulic jack to a portion protruding from the ground of a steel pipe pile so as to increase by 0.5 kN in a cycle for 1 minute, and after applying to a load of 4 kN, it decreases by 1.0 kN. The load is applied as described above, and the displacement amount per minute is measured. The results of the horizontal loading test carried out in this way are shown in FIGS.
FIG. 3 (a) is a table showing the results of a horizontal loading test performed by placing a steel pipe pile in a drilled hole with a drilling diameter of 102mm, and FIG. 3 (b) shows an excavation with a drilling diameter of 127mm. It is the table | surface which showed the result of having placed the steel pipe pile in the hole made and performing the horizontal loading test.
As shown in FIG. 3A, the maximum displacement is 0.50 mm when a load of 3 kN is applied, and as shown in FIG. 3B, the maximum displacement is 0.00 when a load of 4 kN is applied. It was 41 mm.
Therefore, it can be determined that a maximum load of 4 kN can be held with a maximum displacement of 0.50 mm in the horizontal loading test.

<Pullout test>
The pull-out test is for investigating the relationship between the load and displacement by applying a vertical pulling load to the portion of the steel pipe pile protruding from the ground.
As a test method, a portion of the steel pipe pile that protrudes from the ground is given a load that is pulled vertically by a hydraulic jack in increments of 1.20 kN in a 1-minute cycle, and is applied to a load of 9.60 kN, and then 1.40 kN. A load is applied so as to decrease gradually, and the displacement amount per minute is measured.
The results of the pull-out test performed in this way are shown in FIGS.
FIG. 4 (a) is a table showing the result of a pull-out test performed by placing a steel pipe pile in a drilled hole having a drilling diameter of 102 mm, and FIG. 4 (b) is a drilling having a drilling diameter of 127 mm. It is the table | surface which showed the result of having pierced the steel pipe pile in the hole and having done the drawing test.
As shown in FIG. 4A, the maximum displacement amount is 0.28 mm when a load of 9.60 kN is applied. As shown in FIG. 4B, the maximum displacement amount is a load of 9.60 kN. When given, it was 0.14 mm.
Therefore, it can be determined that a maximum load of 9.60 kN can be held with a maximum displacement of 0.28 mm in the pull-out test.

<Indentation test>
The indentation test is for investigating the relationship between load and displacement by applying a load that pushes the steel pipe pile protruding from the ground in the vertical direction.
As a test method, a load that pushes in a vertical direction through a hydraulic jack with a heavy machine to a portion protruding from the ground of a steel pipe pile is given to increase by 1.80 kN in a 1 minute cycle, and after a load of 14.40 kN is given The load is applied so as to decrease by 1.60 kN, and the displacement amount per minute is measured.
The results of the pull-out test performed in this way are shown in FIGS.
FIG. 5 (a) is a table showing the result of the indentation test performed by placing a steel pipe pile in a drilled hole having a drilling diameter of 102mm, and FIG. 5 (b) is a drilling having a drilling diameter of 127mm. It is the table | surface which showed the result of having pushed the steel pipe pile into the hole and having performed the indentation test.
As shown in FIG. 5 (a), the maximum displacement is 0.31 mm when a load of 12.60 kN is applied, and the maximum displacement is 10.80 kN as shown in FIG. 5 (b). When given, it was 0.28 mm.
Therefore, it can be determined that the maximum displacement amount in the indentation test is 0.31 mm, and the maximum load can hold a load of 14.4 kN as shown in the figure.
In each test, the displacement of the steel pipe pile with a bore diameter of 127 mm was smaller than that of the 102 mm steel pipe pile.

From the above test results, the steel pipe pile according to the present embodiment can hold a load of up to 4 kN in the horizontal direction, can hold a load of up to 9.6 kN for drawing, and is maximum for pushing. It is possible to hold a load of 14.4 kN, and it can be determined that there is sufficient horizontal resistance, pull-out resistance, and push-in resistance.
Moreover, it is possible to utilize the steel pipe pile of this invention also as a foundation pile of a large-sized structure, such as a solar panel foundation pile and an apartment building, from such a test result.

<Second Embodiment>
Next, with reference to FIGS. 6-8, the structure of the steel pipe pile which concerns on 2nd Embodiment is demonstrated.
Fig.6 (a) is the front view which showed the structure of the steel pipe pile which concerns on 2nd Embodiment, FIG.6 (b) is the top view which showed the structure of the steel pipe pile which concerns on 2nd Embodiment. is there.
As shown in the drawing, the steel pipe pile 200 includes a pile main body 20, a connection plate 21 integrally attached to the upper end of the pile main body 20 by welding or the like, and a distal end portion 22 at a position away from the lower end of the pile main body 20. The pile main body 20 and the front end portion 22 are connected to each other and a connecting member 23 that is connected.
The pile body 20 is formed of a rectangular pipe having a long shape and a rectangular cross section, and a through hole 20a is formed on each side surface. These through holes 20a are formed at positions having different heights. In addition, the cross-sectional shape of the pile main body 20 is not limited to a rectangular shape, and may be a polygonal shape.
The connection plate 21 is a disk-shaped structure (for example, a structure such as a solar panel) that is installed on the ground, and is fixed to the main body of the steel pipe pile 200, and is connected to the plurality of connection holes 21 a provided in the connection plate 21. Insert the screws and fix the structure.
Similar to the pile main body 20, the distal end portion 22 is formed of a rectangular pipe having a rectangular cross-sectional shape, and has a configuration shorter than the length of the pile main body 20.
In addition, the cross-sectional shape of the front-end | tip part 22 may be a polygon shape similarly, when a pile main body is a polygon shape.

The connecting member 23 is a substantially rectangular and thin plate-shaped member. One end of the connecting member 23 is welded to the side surface of the pile body 20, and the other end is welded to the tip portion 22. And
The connecting member 23 is attached to the lower end of the side surface of the pile body 20. For example, if the cross-sectional shape of the pile body 20 is a rectangular shape, the connecting member 23 is attached to two surfaces so as to be attached to or opposite to each other. And, when the steel pipe pile 200 is driven by a heavy machine or the like, the connecting member 23 is formed with a crease 23a in the width direction of the connecting member 23 in order to be easily bent in a U-shape or It may be bent outward.

  The through-hole 20a formed in the pile main body 20 is a hole for allowing a solidifying agent such as cement milk to leak into the ground, similarly to the through-hole 13 formed in the steel pipe pile 100 of the first embodiment described above. .

Drawing 7 is a figure showing the state where a part of steel pipe pile concerning a 2nd embodiment changed.
As shown in the drawing, when an external force is applied to the steel pipe pile 200 in the vertical direction, the connecting member 23 is not able to withstand the load and bends outward in a dogleg shape. Since the connecting member 23 is thin and has a fold formed as described above or is bent outward in advance, the connecting member 23 is easily bent outwardly by an external force applied to the steel pipe pile 200.
Thus, the horizontal resistance force of the steel pipe pile 200, pull-out resistance force, and pushing-in resistance force can be improved by bending the connection part 23 in the shape of a dogleg in the ground.

FIGS. 8A to 8D are views for explaining a steel pipe pile construction method according to the second embodiment.
First, a heavy machine or the like is used to excavate a depth that is larger than the diameter of the steel pipe pile 200 or a depth at which the upper end of the steel pipe pile 200 protrudes from the ground. Then, crushed stone is put into the excavated hole (FIG. 8A). It should be noted that the size of the crushed stone and the amount of crushed stone can be changed according to the construction status, and for example, 1/4 to 1/3 of the depth of the excavated hole is filled.
By putting a certain amount of crushed stone into the excavated hole, the depth of the plurality of excavated holes can be made constant, and at the same time, it becomes easy to align the height of the cast steel pipe pile 200.

Next, the steel pipe pile 200 is driven into the excavated hole with a heavy machine or the like (FIG. 8B), and the steel pipe pile 200 that reaches the depth of the crushed stone into which the tip of the steel pipe pile 200 is inserted is hit. Thereby, when a compressive stress is applied to the connecting member 23, the connecting member 23 is bent outwardly in a U-shape and becomes larger than the outer diameter of the steel pipe pile 200 (FIG. 8C).
When the steel pipe pile 200 is hit, the distal end portion 22 shows a large resistance against the crushed stone. Therefore, the connecting portion 23 that cannot withstand this resistance is directed outward along the fold line. Bends in a U shape. In addition, the connecting portion 23 is slightly bent with respect to the outer direction in advance, but the connecting portion 23 that cannot withstand the resistance due to the bending in the shape of a U is further formed into a U shape in the outward direction. Bends.

Next, cement milk or cement mortar is poured from the upper end opening of the steel pipe pile 200. Cement milk or cement mortar to be filled leaks into the hole excavated from the gap between the through hole 23 formed in the pile main body 20 and the connecting member 23 bent in a U shape. Cement milk or cement mortar is poured until the inside of the pile body 20 and the excavated hole and the periphery of the steel pipe pile 200 are filled. Thereby, a horizontal resistance force, a drawing resistance force, and a pushing resistance force are improved.
Further, the periphery of the pile body 20 protruding to the ground surface is excavated to a certain depth, and the protruding pile body 20 is covered with the void pipe 300. Then, concrete is placed in the space between the void pipe 300 and the pile main body 20 (FIG. 8D). Thereby, since the pile main body 20 protruded on the ground surface can be fixed to the ground, the horizontal resistance is further increased. Therefore, even if the structure installed on the upper part of the steel pipe pile 200 is blown by the wind, since the pile body 20 protruding to the ground surface is fixed to the ground surface, the steel pipe pile 200 may wobble or come off. Can be prevented.

  As described above, the steel pipe pile according to the second embodiment can be formed of an inexpensive material, and when a force for pushing the connecting portion is applied, the steel pipe pile is bent into a U-shape with respect to the outer direction. By becoming larger than the outer diameter of the main body, it is possible to improve the horizontal resistance force, the pulling resistance force and the pushing resistance force.

DESCRIPTION OF SYMBOLS 100,200 Steel pipe pile 10 Tubular body 11,21 Connection board 11a Connection hole 12 Slit 13, 20a Through-hole 20 Pile main body 22 Tip part 23 Connecting member

Claims (9)

In the steel pipe pile that consists of a hollow steel pipe, constructs the foundation pile structure in the ground by applying a pushing force to the steel pipe and driving it into the ground,
The steel pipe pile is characterized in that a plurality of slits having a predetermined length are formed in the axial direction.   2. The steel pipe pile according to claim 1, wherein an outer diameter of the steel pipe is displaced by the pushing force at a portion where the slit is formed.   The steel pipe pile according to claim 1 or 2, wherein a plurality of the slits are provided in the vicinity of a substantially center of the steel pipe and around the circumference. In the steel pipe pile that consists of a hollow steel pipe, constructs the foundation pile structure in the ground by applying a pushing force to the steel pipe and driving it into the ground,
The steel pipe is a pile body having a polygonal cross-sectional shape,
A tip portion coaxial with the pile body and at a position away from the lower end;
A connecting part for connecting the pile body and the tip part;
The steel pipe pile characterized by being comprised from.   The steel pipe pile according to claim 4, wherein the tip portion has a polygonal cross-sectional shape and is shorter than the length of the pile body.   The connection part is formed in a thin plate shape, and one end of the connection part is fixed to the lower end of the pile body by welding, and the other end of the connection part is fixed to the tip part by welding. The steel pipe pile according to claim 4.   The steel pipe pile according to claim 6, wherein the connecting portion has a crease formed in the width direction or is bent in a U-shape in advance with respect to the outer direction.   The steel pipe pile according to claim 6, wherein the connecting portion is bent outwardly by a pushing force applied to the steel pipe pile. The steel pipe pile according to any one of claims 1 to 8, wherein a plurality of through holes for leakage of a solidifying agent are formed near an upper end or a lower end of the steel pipe.

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