JP2018044400A - Steel pipe pile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an increase in resistance to excavation propulsion of a steel pipe pile during rotary penetration.SOLUTION: A steel pipe pile 1 is formed by welding and fixing an end face plate 3 to a tip surface of a steel pipe 2, which is a pile body. The end face plate 3 has a diameter Dlarger than a steel pipe diameter (d), and also comprises a recessed part 8 with a circular contour of a diameter Drecessed to the pile head side as viewed from the undersurface side in a central part, and comprises a cutout part 5 toward the center from the end face plate peripheral edge in a flange part 4 overhanging to the outer side of the recessed part. On opposite sides in the circumferential direction of the end face plate of the cutout part 5, there are inclined plane parts 6 and 7 inclined in opposite directions to each other vertically. A slender member (an excavation propulsion auxiliary bar) 10 extending toward the vicinity of the cutout part 5 from the central side of the recessed part is fixed to the recessed part 8 by welding. The slender member 10 acts to discharge soil pushed in by being enclosed in the recessed part 8 from the cutout part, and reduces resistance to rotation of a downward inclined plane part from the soil packed in the recessed part, and also reduces an increase in resistance in the vertical direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a steel pipe pile used for a rotary press-fitting method in which a steel pipe which is a pile main body is inserted into the ground by rotary press-fitting.

As this type of steel pipe pile, a circular end face plate with a flange projecting outward from the outer diameter of the steel pipe is fixed to the tip of the steel pipe that is the main body of the pile. There is one in which a circular end plate having a pair of upward and downward inclined surface portions formed by cutting is fixed.
For example, the expanded steel pipe pile of patent document 1 has fixed the enlarged diameter disk 2 which has a downward blade | wing (downward inclined surface part) and an upward blade | wing (upward inclined surface part) in the front-end | tip of the steel pipe 1 which is a pile main body. The code is a code in Patent Document 1).

  Patent document 2 is the structure which fixed to the front-end | tip of the pile main body 5 which consists of a steel pipe the steel wing | blade 3 which formed the upward inclined surface part 13 and the downward inclined surface part 15 on both sides of the cutting part 9 in the collar part (Note The code is the code in Patent Document 2.

Each of the end face plates in the steel pipe piles of Patent Literature 1 and Patent Literature 2 is formed by forming a pair of upward and downward inclined surface portions by incision processing in a flange portion projecting outward from the outer diameter of the steel pipe of a flat disc. However, under the applicant of the present application, as an end face plate fixed to the tip of the steel pipe that is the pile body, it is seen from the lower surface side at the center of a circular plate having an upward inclined surface portion and a downward inclined surface portion formed on the flange portion. A steel pipe pile using an end face plate in which a concave portion is formed on the pile head side was developed and a patent application was filed (Patent Document 3).
With the simple means of forming a recess recessed in the center of the end face plate on the pile head side, it has become possible to increase the support capacity of the pile at a low cost and without impairing the workability.

JP 2006-9354 A JP 2010-281205 JP2015-195486A

Since the steel pipe pile of patent document 3 has a recessed part in the center part of an end face plate, when it penetrates into the ground, the contact surface with the ground works effectively because soil is clogged in the recessed part, and it is possible to reliably secure the supporting force. However, at the time of the rotation penetration, it was found that the phenomenon that the resistance to excavation propulsion was increased by the soil being enclosed and pushed into the recess.
That is, during rotation penetration, the soil is surrounded and pushed by the concave portion particularly at the downward inclined surface portion, so that resistance to rotation of the downward inclined surface portion from the soil jammed in the concave portion is increased, and resistance in the vertical direction is also increased.

  The present invention has been made based on the above background, and when a steel pipe pile with an end plate having a concave portion in the center portion fixed to the tip of the pile body is penetrated into the ground, the supporting force to the ground is ensured after the penetration. An object of the present invention is to provide a steel pipe pile that can be secured and can prevent an increase in resistance to excavation of the steel pipe pile when rotating.

The invention according to claim 1 to solve the above problems, the distal end surface of the steel pipe is pile body, with greater than steel pipe diameter d diameter D _0, and the central portion, recessed into the pile head side as viewed from the lower surface side diameter A circular end face plate formed with a concave portion having a circular contour of D ₁ is welded and fixed, and has a notch portion extending from the periphery of the end face plate toward the center in a flange portion protruding outward from the concave portion in the end face plate, In the steel pipe pile in which inclined surface portions inclined in the opposite directions are formed on both sides in the circumferential direction of the end face plate of the notch portion, an elongated member extending from the center side to the vicinity of the notch portion is formed in the concave portion. It is characterized by being fixed by welding.

  According to a second aspect of the present invention, the steel pipe pile according to the first aspect is provided with an inclined surface portion reinforcing member welded and fixed to the lower surface of the end surface plate and welded and fixed to the side end surface on the end surface plate center side in the inclined surface portion inclined downward. It is characterized by that.

According to the steel pipe pile of the invention of claim 1, resistance to the excavation and propulsion of the steel pipe pile is obtained by welding and fixing the elongated member extending from the center side toward the vicinity of the notch portion in the concave portion on the back surface of the end face plate. Can be suppressed.
That is, when rotating and penetrating, the downward inclined surface portion acts to surround and push the soil to be excavated into the concave portion, but an elongated member extending from the center side to the vicinity of the notch portion is provided in the concave portion on the back surface of the end face plate. Since it exists as an excavation propulsion auxiliary bar, this elongated member is enclosed in the recess and acts to discharge the pushed-in soil from the notch. Therefore, the clogging of the soil into the concave portion during excavation promotion is suppressed, the resistance to the rotation of the downward inclined surface portion from the soil clogged with the concave portion is reduced, and the increase in the vertical resistance is also reduced.

  Since the downward inclined surface portion receives a large resistance to the action of excavating the soil, there is a risk of deformation due to the large resistance. According to claim 2, the downward inclined surface portion is connected to the end through the inclined surface portion reinforcing member. Since it is connected to the face plate, the downward inclined surface portion is prevented from being deformed.

It is a front view of the steel pipe pile of one Example of this invention. It is a top view of FIG. 1 (however, the steel pipe which is a pile main body is shown with the cross section). It is AA sectional drawing of FIG. It is a bottom view of FIG. (A) is an enlarged view of the principal part seen from the B arrow direction of FIG. 2, (b) is a figure explaining the junction part (sand part hatching part) with the downward inclined surface part in the inclined surface part reinforcement member of (b). . FIG. 5 is a bottom view of a disk (a figure corresponding to FIG. 4), showing a state where a cut is made in order to form an inclined surface part in the disk in the step of manufacturing the end face plate. It is a figure explaining an example of the aspect which constructs the steel pipe pile of this invention as a foundation pile of a house.

  Hereinafter, the form for implementing the steel pipe pile of this invention is demonstrated with reference to drawings.

1 is a front view of a steel pipe pile according to an embodiment of the present invention, FIG. 2 is a plan view of FIG. 1 (however, a steel pipe as a pile body is shown in cross section), and FIG. FIG. 4 is a bottom view of FIG. 1.
This steel pipe pile 1 has a circular contour with a diameter D ₁ at the tip end surface of the steel pipe 2 which is a pile body and having a diameter D ₀ larger than the steel pipe diameter d and indented on the pile head side when viewed from the lower surface side in the center. The circular end face plate 3 in which the concave portion 8 is formed is fixed by welding. The recess 8 in the illustrated example has a mortar shape. The circular contour of the recess 8 is indicated by S in FIG. The outer portion (upper surface portion) of the recess 8 is indicated by 8 ′. A circular contour viewed from above the outer portion 8 ′ of the recess 8 is denoted by S ′.
The end face plate 3 has a notch 5 extending from the periphery of the end face plate 3 toward the center on the flange portion 4 projecting outward from the concave portion 8. Inclined surface parts 6 and 7 (upwardly inclined surface part 6 and downwardly inclined surface part 7) inclined in the upside down direction are formed.
And the elongate member 10 which functions as an excavation promotion auxiliary bar extended from the center side toward the vicinity of the said notch part 5 is weld-fixed by the said recessed part 8. As shown in FIG. The elongated member 10 of the embodiment is a square bar (square member) having a square cross section of 18 mm in length and width and a length of 130 mm.

In this embodiment, an inclined surface portion reinforcing member 21 that reinforces the downward inclined surface portion 7 is welded and fixed to the lower surface of the end face plate 3.
The inclined surface portion reinforcing member 21 in the illustrated example is a square bar having a square cross section of 18 mm in length and width, and a length of 40 mm. The lower end of the inclined surface portion reinforcing member 21 is in contact with the side surface of the end surface plate in the downward inclined surface portion 7. The upper side surface is welded and fixed to the side end surface of the downward inclined surface portion 7 on the center side of the end surface plate. The portion indicated by sandy hatching in FIG. 5B is a region where the inclined surface portion reinforcing member 21 and the side end surface of the downward inclined surface portion 7 on the center side of the end surface plate are joined. Welding takes place around the area. In FIG. 2, the weld is indicated by Q.
The position where the inclined surface portion reinforcing member 21 in the illustrated example is fixed to the end surface plate 3 is a flat portion between the circular contour S of the concave portion 8 and the circular arc cut m.
In addition, when the diameter of the end surface plate 3 is small, the position of the inclined surface portion reinforcing member 21 may be the inclined surface of the concave portion 8. In this case, the lower end surface of the inclined surface portion reinforcing member 21 is an inclined surface.

The steel pipe 2 which is the pile body of the steel pipe pile 1 usually has a thickness t of 4.2 mm, 5.5 mm, 5.7 mm, 6.0 mm, etc., and a diameter d of 89.1 mm, 101.6 mm, 114.3 mm. Etc. The material is STK400.
The end face plate 3 usually has a plate thickness T = 9 mm, 12 mm, etc., and a diameter D ₀ = 300 mm, 400 mm, 580 mm, etc. The material is SS400 or SS490. The height of the recess 8 is usually H = 45 mm, 60 mm, 75 mm, etc., and the diameter D ₁ of the circular contour S of the recess 8 is usually 175 mm, 220 mm, 280 mm, 360 mm, etc.
About each size etc. of the steel pipe pile demonstrated in an Example, the steel pipe 2 is plate | board thickness t = 4.5mm, diameter d = 14.3mm, and material STK400. The end face plate 3 has a thickness T = 9 mm, a diameter D ₀ = 400 mm, and a height H of the recess 8 = 45 mm. The diameter _{D 1} of the circular profile S of the concave portion 8 is 220 mm, material is SS400 or SS490.

The method of manufacturing the end face plate 3 is not particularly limited, but the inclined surface portions 6 and 7 may be formed after forming the concave portion 8 in the flat disk of the steel plate, or the inclined surface portions 6 and 7 may be formed in the flat disk. You may form the recessed part 8 in the step which made the notch for forming. It is also conceivable to form a recess after making a cut in a flat disk and forming an inclined surface portion.
In FIG. 6 shown as a bottom view corresponding to FIG. 4, the inclined surface portion is formed after the concave portion 8 is formed in the disk 9. In the figure, the end face plate at the stage before the inclined surface portion is formed is indicated by 3 ', and the portions that become the inclined surface portions 6 and 7 are indicated by 6' and 7 '.
In the illustrated example, an arc-shaped cut m is made at a position slightly outward in the radial direction from the circular contour S of the concave portion 8, and a cut n extending radially outward from the center position of the arc-shaped cut m is made, and then the cut The both sides in the circumferential direction of n are inclined in the upside down direction to form the inclined surface portions 6 and 7 in the upside down direction as shown in FIGS. 1, 3, and 5. In FIG. 6, which is a bottom view, the valley fold when forming the inclined surfaces 6 and 7 is indicated by a one-dot chain line, and the mountain fold is indicated by a two-dot chain line.
In addition, although related to the dimensional difference between the diameter D ₀ of the end face plate 3 and the diameter D ₁ of the circular contour S of the recess 8, the inclined surface portion reinforcing member is interposed between the arc-shaped cut m and the circular contour S. It is desirable to ensure a flat space for fixing the lower end of 21 to the end face plate 3 by welding.

When the steel pipe pile 1 described above is driven into the ground, the pile is penetrated into the ground by rotary press-fitting with a pile driving machine having a rotary press-fit drive unit.
In this case, the end face plate 3 at the tip exhibits a driving force in such a manner that the inclined surface portions 6 and 7 bite into the soil. And in the state which the end surface board 3 reached | attained the support layer, the contact surface with a ground works effectively because the clogging of the recessed part 8 of a lower surface becomes a thing with high support power.

When the steel pipe pile 1 is penetrated into the ground by rotary press-fitting, since the concave portion 8 is provided in the central portion of the end face plate 3, contact with the ground due to the soil being clogged in the concave portion 3 when penetrating into the ground as described above. Although the surface works effectively and can secure the supporting force reliably, the resistance to excavation propulsion is great when the soil is surrounded and pushed into the concave portion 8 by the downward inclined surface portion 7 in particular when rotating and penetrating. It becomes a factor. That is, if the soil is excessively pushed into the concave portion 8 by the downward inclined surface portion 7 during the rotation penetration, the resistance to the rotation of the downward inclined surface portion 7 from the soil jammed in the concave portion 8 is increased, and the vertical resistance is also increased. Increase.
However, in the steel pipe pile 1 described above, since the elongated member 10 extending from the center side toward the vicinity of the notch portion 5 exists in the concave portion 8 on the back surface of the end face plate 3, the elongated member 10 is provided during excavation propulsion. It acts to discharge the soil that is enclosed and pushed into the recess 8. Therefore, the soil is prevented from clogging into the concave portion 8, the resistance to the rotation of the downward inclined surface portion 7 from the soil jammed in the concave portion 8 is reduced, and the vertical resistance is also reduced. Thus, the elongated member 10 functions as an excavation promotion auxiliary member.

  As described above, particularly the downward inclined surface portion 7 of the end face plate 3 receives a great resistance to the action of excavating the soil. Therefore, the downward inclined surface portion 7 may be deformed by the resistance. However, since the downward inclined surface portion 7 is coupled to the end face plate 3 via the inclined surface portion reinforcing member 21, the downward inclined surface portion 7 has an inclination angle. Further deformation to be larger is prevented.

FIG. 7 illustrates an example of an embodiment in which the above-described steel pipe pile 1 is constructed as a foundation pile of a building such as a house. The steel pipe pile 1 is installed on the ground in a form that supports the foundation concrete 20 of the building. . According to the steel pipe pile 1, since the ground supporting force is improved, a desired supporting force can be ensured with fewer piles than in the past.
Moreover, when penetrating the steel pipe pile 1 into the ground, as described above, the resistance to the excavation and propulsion of the steel pipe pile 1 is reduced by the elongated member 10 fixed to the lower surface of the end face plate 3.

In the above-described embodiment, a square member having a square cross section is used as the elongated member. However, the rectangular member is not limited to a square cross section, and may be a rectangular cross section. Furthermore, a plate-like member having a remarkably larger height dimension than a width dimension may be used.
Further, the arrangement (position) of the elongated member 10 in the recess 8 is arranged and fixed in such a manner that it extends from the center side of the recess toward the vicinity of the notch 5, but when the end face plate 3 rotates and propels the excavation. The soil's behavior is complex, so its position is not strictly determined. Therefore, it is possible to obtain an appropriate elongated member shape and arrangement by conducting experiments on various arrangements.
The concave portion 8 of the embodiment has a mortar shape, but may have a bowl shape. In this case, the entire length of the elongated member 10 does not contact the surface of the recess 8, but the presence of a slight gap is not particularly a problem as a function of the elongated member.

Although illustration is omitted, a plate-like excavation blade can be fixed to the lower surface of the end face plate 3 by welding. In this case, the excavating blade has a blade portion with a sharp tip in the tip side (lower end side) and a base portion (upper end side) matched to the surface of the recess, and the base is welded and fixed vertically to the recess 8. To do. This excavating blade agitates the soil, so that the force required for press-fitting the steel pipe pile can be reduced.
Moreover, although illustration is abbreviate | omitted, an auxiliary | assistant wing can be attached to the upper position (for example, about 50 to 60% upper position of an end surface plate diameter) suitably from the position of the end surface plate 3 in the steel pipe pile 1. FIG. The auxiliary wing in this case is a shape excluding the elongated member 10 and the inclined surface portion reinforcing member 21 in the end face plate 3 at the tip, and the size is increased by, for example, about 20%.

1 Steel pipe pile 2 Steel pipe (pile body)
3 End face plate 3 ′ End face plate 4 before the inclined face portion is formed 4 ridge part 5 notch part 6 upward inclined face part 6 ′ upper inclined face part 7 downward inclined face part 7 ′ downward inclined face part 8 Recess 8 'Outer portion of recess 10 Elongated member (excavation propulsion auxiliary bar)
21 Inclined surface portion reinforcing member S Circular contour S 'of concave portion Circular contour T of outer portion of concave portion viewed from above Plate thickness t (of end plate) Plate thickness d (of steel tube) Diameter D of steel tube ₀ Diameter of end plate D ₁ Diameter of the circular contour of the recess H Height of the recess

Claims (2)

The distal end surface of the steel pipe is pile body, with greater than steel pipe diameter d diameter D _0, and the central portion, the recess of the circular contour of the recessed diameter D ₁ in the pile head side as viewed from the lower surface side is formed a circular The end face plate of the end face plate is welded and fixed, and has a notch extending from the periphery of the end face plate toward the center on the flange portion that protrudes outward from the concave portion of the end face plate. In the steel pipe pile in which the inclined surface part inclined in the upside down direction is formed, an elongated member extending from the center side toward the vicinity of the notch is welded and fixed to the recess. The steel pipe pile according to claim 1, further comprising an inclined surface portion reinforcing member welded and fixed to a lower surface of the end surface plate and welded and fixed to a side end surface on the end surface plate center side in an inclined surface portion inclined downward. .

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