Steel pipe pile with rotation stabilizing member attached to the end plate

Abstract

To provide a steel pipe pile having an end surface plate having upside-down inclined surface parts, which prevents inclination of the end surface plate due to a load acting on a downward inclined surface part on the end surface plate.SOLUTION: A steel pipe pile has inclined surface parts 7 and 8 which are inclined upside down in a flange part 6 of an end surface plate 4 fixed to a tip of a shaft part 2. On a rear face of the inclined surface part 8 inclined downward, a rotary stabilization member 15 for rotating the end surface plate 4 in a stable horizontal attitude is provided. The rotary stabilization member 15 has an acute angle tip part 15a which is formed in an arcuate shape in parallel with an arcuate outer edge of the end surface plate 4, and projects from the tip of the downward inclined surface part 8 and forms an acute angle. When the steel pipe pile is rotated and pressed-in, large force acts on the inclined surface part 8 inclined downward in a horizontal direction, and acts thereon so as to incline the end surface plate 4, but the acute angle tip part 15a fixed to the rear face of the inclined surface part 8 inclined downward acts to reduce the force in the horizontal direction acting on the downward inclined surface part 8, which prevents inclination of the end surface plate 4.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a steel pipe pile used in a rotary press-in method for penetrating the ground by rotatably pressing a steel pipe as a pile body, and particularly to a tip member provided with an end face plate fixed to the lower end of the steel pipe as the pile body.

Background Art

[0002] There is a steel pipe pile of Cited Document 1 shown in FIG. 7 as this type of steel pipe pile. Explaining with reference numerals in Cited Document 1, this steel pipe pile has an end face plate (steel wing in Patent Document 1) 3 having inclined surface portions 13 and 15 inclined in opposite directions up and down on the tip end face of a steel pipe 5 which is the axial portion of the steel pipe pile, and is welded and fixed. In this steel pipe pile, when the steel pipe is rotatably pressed, the inclined surface portions 13 and 15 inclined in opposite directions up and down exert a propulsive force due to the rotation of the steel pipe. This end face plate can be manufactured by making a cut in a disk of material, cutting out a predetermined range in a fan shape, and forming inclined surface portions 13 and 15 inclined in opposite directions up and down on both sides of the cut-out portion.

[0003] The end face plate 3 of Patent Document 1 has inclined surface portions 13 and 15 with opposite inclinations provided on one side in the diameter direction of the end face plate 3, but there may also be a case where inclined surface portions 13 and 15 with opposite inclinations are provided on both sides in the diameter direction of the end face plate 3.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the steel pipe pile described in Patent Document 1, the downward-sloping surface portion 15 of the inclined surfaces 13 and 15, which are tilted in opposite directions due to the rotation of the steel pipe, exerts thrust. However, in the case of ground that is hard enough or when there are obstacles, there is a problem that the end plate 3 tilts due to the load acting on the downward-sloping surface portion 15 in particular. Furthermore, it seems that such problems could be avoided by providing inverted inclined surfaces 13 and 15 on both sides of the end plate 3 in the diametrical direction, but this would increase manufacturing costs.

[0006] The present invention has been made in view of the above circumstances, and aims to provide a steel pipe pile having a tip member provided with an inverted inclined surface portion on one side of the end plate in the diametrical direction, in which the end plate can be prevented from tilting due to a load acting on the downward inclined surface portion in particular. [Means for solving the problem]

[0007] Claim 1: The above problem has been solved. related The invention is, A steel pipe pile 1 is installed in the ground by a rotary press-in method, in which a tip member 3 that generates thrust through rotation is fixed to the tip of a shaft portion 2 made of steel pipe, The tip member 3 is fixed to the tip surface of the shaft portion 2. It is equipped with an end plate 4, The end plate 4 is The aforementioned Outer circumferential surface of shaft portion 2 From the direction perpendicular to the axis, radially outside Extends Guard part 6 and, From the flange portion 6 on one side in the diametrical direction of the end plate 4 They are tilted in opposite directions. Upward extension Slope section 7 and downward inclined surface 8 and It has, The aforementioned Downward tilt Sloping section 8 under On the surface, The aforementioned A rotation stabilizing member 15 is fixed to the end plate 4 to allow it to rotate in a stable horizontal position. The rotation stabilizing member 15 is The aforementionedParallel to the arcuate outer edge of the end face plate 4 Extending from the lower surface of the flange portion 6 to the lower surface of the downward inclined surface portion 8 and The aforementioned An acute-angled tip portion that forms an acute angle protruding from the tip of the downwardly inclined surface portion 8 15a characterized by having.

[0008] Claim 2 Invention relating to is the steel pipe pile according to claim 1, wherein the downwardly inclined surface portion 8 teeth, is an acute angle with a taper on the upper surface side Having a tip portion 8a characterized by this.

[0009] Claim 3 Invention relating to is the steel pipe pile according to claim 1 or 2, on the lower surface of the end face plate 4,<s The aforementioned end face plate 4 On the opposite side of the rotation stabilization member 15 with the center of the end face plate in between, The aforementioned end face plate 4 For the auxiliary function of stabilizing the rotation of the end face plate at least one block 16 characterized by being fixed. The invention according to claim 4 is a steel pipe pile according to claim 3, wherein at least one block 21 is the widthwise center line L of the downward inclined portion 8. 1 It is characterized by including a pair of blocks 16, 16 arranged symmetrically with respect to a central element.

[0010] Claim Invention related to 5 is the steel pipe pile according to claim 1 or 2 wherein the rotation stabilization member 15 is arranged side by side at a plurality of locations in the radial direction of the end face plate 4, characterized by this. The aforementioned arranged side by side at a plurality of locations in the radial direction of the end face plate 4, characterized by this.

[0011] Claim Invention related to 6 is the steel pipe pile according to claim 1 or 2 wherein a pointed plate-shaped excavation blade 5 vertically fixed to the center of the lower surface of the end face plate 4 is provided, characterized by this.

Advantages of the Invention

[0012] Claim 1 relatedIn the invention, when a steel pipe pile is driven in by rotation, a large horizontal force acts on the inclined surface portion 8, which is inclined in opposite directions, particularly the downward-sloping inclined surface portion. If inclined surfaces in opposite directions are provided on both sides of the end plate in the diametrical direction, the forces acting on both inclined surfaces are expected to balance each other. However, if they are provided on only one side, the end plate may tilt (it may no longer be able to maintain a horizontal position). However, in this invention, a rotation stabilizing member 15 is fixed to the back surface of the downward-sloping inclined surface portion 8. The rotation stabilizing member 15 has an arc shape that is parallel to the arc-shaped outer edge of the end plate 4 and has an acute-angled tip portion 15a that protrudes from the tip of the downward-sloping inclined surface portion 8 and forms an acute angle. The presence of this rotation stabilizing member 15 reduces the horizontal force acting on the downward-sloping surface portion 8, thereby preventing the end plate 4 from tilting.

[0013] Claim 2 Invention relating to According to this, since the tip of the downward-sloping surface portion 8 is not a right-angle surface but has an acute angle with a taper on the upper side, the horizontal force acting on the tip of the downward-sloping surface portion 8 is also reduced, and in combination with the presence of the rotation stabilizing member 15, the end plate 4 can be effectively prevented from tilting.

[0014] Claim 3 Invention relating to According to this, since the block 21, which serves to assist in the rotational stabilization of the end plate 4, is fixed on the opposite side of the rotational stabilization member 15 with the center of the end plate in between, the effect of preventing the end plate 4 from tilting can be enhanced.

[0015] Claim Invention related to 5 According to this, by arranging the rotation stabilizing members 15 at multiple locations in the radial direction of the end plate, the effect of preventing the end plate 4 from tilting is enhanced. [Brief explanation of the drawing]

[0016] [Figure 1] This shows the vicinity of the lower end of a steel pipe pile according to one embodiment of the present invention, where (a) is a front view and (b) is a plan view of (a) with cross-section AA. [Figure 2]This is a bottom view of the steel pipe pile in Figure 1 (a view of Figure 1(b) from the bottom side). [Figure 3] (a) is a diagram showing Figure 2 rotated to the right by an angle α to make it easier to explain the operation of the present invention, (b) is a view from arrow B in (a), and (c) is a view from arrow C in (a). [Figure 4] To facilitate the explanation of the operation of the present invention, Figure 3(b) is shown inverted vertically and enlarged (Note that the view from arrow D in Figure 1(b) is the opposite of Figure 4 horizontally, but for ease of explanation, Figure 3(b) is simply shown inverted). [Figure 5] This figure illustrates the rotation stabilizing member 15, which is the main part of the present invention. (a) and (b) show the flat plate stage, cut from a sheet material with an acute angle (angle β (20° in the illustrated example)) at the tip. (a) is a plan view, and (b) is a side view. (c) is a side view of the rotation stabilizing member 15 after being tilted at angle β. [Figure 6] This figure shows an embodiment in which two rotation stabilizing members of different lengths are provided side by side at two locations in the radial direction of the end plate. [Figure 7] This figure shows the vicinity of the lower end of a conventional steel pipe pile (Patent Document 1). [Modes for carrying out the invention]

[0017] The embodiments for implementing the steel pipe pile of the present invention will be described below with reference to the drawings. [Examples]

[0018] Figure 1 shows the vicinity of the lower end of a steel pipe pile 1 according to one embodiment of the present invention, where (a) is a front view and (b) is a plan view of (a) with cross-section AA. Figure 2 is a bottom view of the steel pipe pile 1 of Figure 1 (a view of Figure 1(b) from below). This steel pipe pile 1 has a tip member 3 fixed to the tip of a shaft portion 2 made of steel pipe, which generates thrust through rotation during rotary press-fitting. The tip member 3 comprises an end plate 4 welded to the tip surface of the shaft portion 2, and a pointed, plate-shaped drilling blade 5 that is vertically welded to the center of the lower surface of the end plate 4. The end plate 4 has inclined surfaces on the flange portion 6, which is the outer part of the outer circumferential surface of the shaft portion 2, that are inclined in opposite directions, namely an upwardly inclined upward inclined surface portion 7 and a downwardly inclined downward inclined surface portion 8. These inclined surfaces 7 and 8 of the end plate 4, which are inclined in opposite directions, exert thrust when rotated during press-fitting. The end plate 4 has a circular central hole 9 in its center, and the drilling blade 5 has a notch 5a that matches the central hole 9. Reinforcing members 10 are provided on both sides of the drilling blade 5.

[0019] In this invention, a rotation stabilizing member 15 is welded and fixed to the back surface of the downward-sloping inclined surface portion 8 to allow the end plate 6 to rotate in a stable horizontal position. Figure 3(a) is a diagram showing Figure 2 rotated to the left by an angle α to facilitate explanation of the operation of the present invention, (b) is a view from arrow B in (a), and (c) is a view from arrow C in (a). The angle α is such that the widthwise center line L1 of the downward inclined surface portion 8 in Figure 2 becomes a vertical line on the drawing as shown in Figure 3. The rotation stabilizing member 15 has an arc shape that is parallel to the arc-shaped outer edge of the end plate 4 in a plan view, and as shown in Figure 4, it has an acute-angled tip portion 15a that protrudes from the tip of the downward-sloping surface portion 8 and forms an acute angle. In the illustrated example, the acute-angled tip portion 15a has a horizontal lower surface 15aa. The tip of the downward-sloping surface portion 8 also has an acute-angled tip portion 8a with a tapered upper surface. Note that in Figures 3(b) and 4, the upward-sloping surface portion 7 is not shown, and the flat portion of the end plate 4 is shown instead.

[0020] On the lower surface of the end plate 4, on the side opposite the rotation stabilizing member 15 with the center of the end plate in between, a pair of plate-shaped blocks 16, 16 are fixed, which perform an auxiliary function that contributes to the stable rotation of the end plate 4. This pair of blocks 16, 16 are provided symmetrically on either side of the widthwise center line L1 of the downward inclined surface portion 8, and as shown in Figure 3(c), they have a rectangular shape with the outer upper parts on either side of the center line L1 cut out. Furthermore, the pair of blocks 16, 16 can be connected to form a single integrated block.

[0021] In the steel pipe pile 1 described above, when the steel pipe pile 1 is rotated and pressed into place, a large horizontal force acts on the inclined surfaces 7 and 8, particularly the downward-sloping inclined surface 8, which are inclined in opposite directions. If the inclined surfaces 7 and 8, which are inclined in opposite directions, are provided on both sides of the end plate 4 in the diametrical direction in a plan view, the forces acting on both inclined surfaces are thought to be balanced. However, if they are provided on only one side, the end plate may tilt (become unable to maintain a horizontal position), as mentioned above in the section on the problem to be solved. However, in this invention, a rotation stabilizing member 15 is fixed to the back surface of the downward-sloping inclined surface portion 8. The member 15 has an arc shape that is parallel to the arc-shaped outer edge of the end plate 4 and has an acute-angled tip portion 15a that protrudes from the tip of the downward-sloping inclined surface portion 8 and forms an acute angle. The presence of this rotation stabilizing member 15 reduces the horizontal force acting on the tip of the downward-sloping surface portion 8, thereby preventing the end plate 4 from tilting. Furthermore, since the tip of the downward-sloping surface portion 8 is not kept at a right angle but the upper side is tapered to a sharp angle 8a, the horizontal force acting on the tip of the downward-sloping surface portion 8 is also reduced, and in combination with the presence of the rotation stabilizing member 15, the end plate 4 can be effectively prevented from tilting. Furthermore, since a pair of left and right blocks 16, 16 are fixed on the opposite side of the rotation stabilization member 15, with the center of the end plate in between, to assist in the rotation stabilization of the end plate 4, the effect of preventing the end plate 4 from tilting can be enhanced.

[0022] As an example, the dimensions of each part of the tip member 3 in the embodiment are as follows: the diameter of the end plate 4 is 800 mm, the thickness is 45 mm, the thickness of the rotation stabilizing member 15 is 30 mm, the inclination angle of the downward inclined surface portion 8 and the rotation stabilizing member 15 is 20°, and the height h is 20 mm. The rotation stabilizing member 15 is positioned radially 10 mm away from the outer circumference of the end plate 4. The dimensions mentioned above are just examples and are not limiting to any particular case.

[0023] Figure 5 shows the processing procedure for the rotation stabilization member 15. Figure 5(a) is a plan view of the rotation stabilizing member 15 before bending, Figure 5(b) is a side view thereof, and Figure 5(c) is a side view of the member after bending. [Examples]

[0024] Figure 6 shows another embodiment of the tip member. This tip member 3' is the same as the tip member 3 in Figure 2, but with a rotation stabilizing member 15' also provided on the end plate center side in the width direction of the downward inclined surface portion 8. By providing two rotation stabilizing members 15 and 15' on both the outer and inner circumference sides in the width direction of the downward inclined surface portion 8, not only is the effect of preventing the end plate 4 from tilting enhanced, but the horizontal force acting on the tip portion 15a' of the downward inclined surface portion 8 is also reduced in a balanced manner, thereby effectively preventing the end plate 4 from tilting. Although not shown in the diagram, it is also possible to use a single wide rotation stabilizing member that is close to the width of the downward-sloping surface portion 8. [Explanation of Symbols]

[0025] 1 steel pipe pile 2. Shaft section 3. Tip member 4 End plate 5 drilling blades 5a notch 6. Guard section 7 Upward inclined surface 8 Downward slope section 9 center hole 10 Reinforcement members 15, 15' Rotational stabilizing member 15a, 15a' Acute tip 15aa (Underside of the acute-angled tip) 16 blocks

Claims

1. A steel pipe pile installed in the ground by a rotary press-in method, in which a tip member that generates thrust through rotation is fixed to the tip of a shaft made of steel pipe, The tip member comprises an end plate fixed to the tip surface of the shaft portion, The end plate is, A flange portion extending radially outward in a direction perpendicular to the axial direction from the outer circumferential surface of the shaft portion, On one side of the end plate in the diametrical direction, there is an upward-sloping portion and a downward-sloping surface portion that extend from the flange portion in opposite directions. It has, A rotation stabilizing member is fixed to the lower surface of the flange portion and the downward inclined surface portion to allow the end plate to rotate in a stable horizontal position. The rotation stabilizing member is characterized in that it extends from the lower surface of the flange portion to the lower surface of the downward inclined surface portion parallel to the arc-shaped outer edge of the end plate, and has an acute-angled tip portion that protrudes from the tip of the downward inclined surface portion and forms an acute angle.

2. The steel pipe pile according to claim 1, characterized in that the downward-sloping surface portion has an acute-angled tip portion that tapers on the upper side.

3. The steel pipe pile according to claim 1 or 2, characterized in that at least one block is fixed on the lower surface of the end plate, on the side opposite to the rotation stabilizing member, with the center of the end plate in between, to perform an auxiliary function for stabilizing the rotation of the end plate.

4. The steel pipe pile according to claim 3, characterized in that the at least one block includes a pair of blocks arranged symmetrically across the widthwise centerline of the downward-sloping portion.

5. The steel pipe pile according to claim 1 or 2, characterized in that the rotation stabilizing members are arranged in a plurality of locations in the radial direction of the end plate.

6. The steel pipe pile according to claim 1 or 2, further characterized by comprising a pointed, plate-shaped drilling blade fixed vertically to the center of the lower surface of the end plate.

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