steel pipe Hangzhou

Abstract

The present invention provides a steel pipe pile that can prevent deformation of the upper portion of each blade of the pile body when the steel pipe pile is pressed into the ground. [Solution] In the steel pipe pile P, two slits 11 and 12 are formed at the lower end of the pile body 10 for fitting two wings 21 and 22. The bit 30 is plate-shaped and extends radially across the pile body 10, with both ends in the radial direction welded to the inner circumferential surface of the pile body 10. The two wings 21 and 22 are each fitted into the two slits 11 and 12 and welded to the plate surface of the bit 30. The two upper support plates 41 and 42 are plate-shaped and positioned perpendicular to the bit 30. One of the end faces perpendicular to the bit 30 is welded to the plate surface of the bit 30, and the other is welded to the center of the inclination direction of the two wings 21 and 22 on the inner circumferential surface of the pile body 10.

Description

Technical Field

[0001] The present invention relates to steel pipe piles.

Background Art

[0002] Conventionally, as described in Patent Document 1 below, for example, a steel pipe pile is known that includes a cylindrical pile body, one bit protruding downward from the lower end of the pile body, and two blades provided at the lower end of the pile body. The bit has a plate shape that crosses the pile body in the radial direction, and both end faces in the radial direction are welded to the inner peripheral surface of the pile body. The two blades both project outward from the outer peripheral surface of the pile body and are inclined with respect to the horizontal plane in a side view. The steel pipe pile is press-fitted into the ground by rotating it while pressing the pile body vertically downward. At this time, the bit excavates the ground directly below the pile body, and the two blades bite into the ground around the pile body.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the steel pipe pile is press-fitted into the ground, since the two blades bite into the ground around the steel pipe pile, a vertically upward force and a force opposite to the rotation direction of the steel pipe pile act on the lower end portion in the inclination direction of each blade. The force acting on the lower end portion in the inclination direction of each blade strongly acts on the upper portion of the pile body above each blade, particularly on the portion located behind the steel pipe pile in the rotation direction from the lower end portion in the inclination direction of each blade. For this reason, when press-fitting the steel pipe pile into the ground, there has been a desire to prevent deformation such as the upper portion of the pile body above each blade being recessed inward.

[0005] This invention was proposed in view of the above circumstances, and provides a steel pipe pile that can prevent deformation of the upper portion of each wing of the pile body when the steel pipe pile is pressed into the ground. [Means for solving the problem]

[0006] In other words, the first invention comprises a cylindrical pile body, a bit disposed inside the lower end of the pile body and protruding downward from the lower end of the pile body, two wings provided at the lower end of the pile body, extending radially outward from the outer surface of the pile body and inclined to intersect each other with respect to the horizontal plane in a side view, and two upper support plates provided above each of the two wings inside the lower end of the pile body, wherein two slits are formed at the lower end of the pile body for fitting the two wings, and the bit The present invention relates to a steel pipe pile characterized in that the pile body is plate-shaped and extends radially across it, with both ends in the radial direction welded and fixed to the inner circumferential surface of the pile body, the two wings are each fitted into the two slits and welded and fixed to the plate surface of the bit, and the two upper support plates are each plate-shaped and positioned perpendicular to the bit, with one of the end faces perpendicular to the bit welded and fixed to the plate surface of the bit, and the other end welded and fixed to the inner circumferential surface of the pile body at the center position in the inclination direction of each of the two wings.

[0007] The second invention relates to a steel pipe pile, characterized in that, in the first invention, it comprises two lower support plates provided inside the lower end of the pile body on the lower side of each of the two wings, the two lower support plates are plate-shaped and arranged perpendicular to the bit, and both end faces perpendicular to the bit are welded and fixed to the plate surface of the bit and the inner circumferential surface of the pile body.

[0008] The third invention relates to a steel pipe pile, characterized in that, in the second invention, the two lower support plates have protruding portions that extend downward from the lower end of the pile body, and the protruding portions have inclined surfaces that slope downward toward the radial center of the pile body. [Effects of the Invention]

[0009] According to the steel pipe pile of the first invention, the portion of the pile body above each wing, located behind the lower end of each wing in the direction of inclination in the direction of rotation of the steel pipe pile, is prevented from deforming inward by two upper support plates. Therefore, when the steel pipe pile is pressed into the ground, deformation of the portion of the pile body above each wing can be prevented.

[0010] According to the steel pipe pile of the second invention, in the first invention, the lower end of the pile body is reinforced by two lower support plates, so deformation of the lower end of the pile body can be prevented more reliably.

[0011] According to the steel pipe pile of the third invention, in the second invention, the ground directly beneath the pile body can be efficiently crushed by the bit and the two lower support plates, thereby improving the driving efficiency. [Brief explanation of the drawing]

[0012] [Figure 1] This is a perspective view of the lower end of a steel pipe pile in Example 1, showing two wings, a bit, two upper support plates, and two lower support plates. [Figure 2] This is an exploded front view showing the lower end of a steel pipe pile. [Figure 3] This is a plan view showing steel pipe piles. [Figure 4] This is a side view showing the lower end of a steel pipe pile. [Figure 5] This is a front view showing the lower end of a steel pipe pile. [Figure 6] This is a conceptual diagram showing how steel pipe piles are rotated and pressed into the ground. [Figure 7] This is a front view showing the lower end of the steel pipe pile in Example 2. [Modes for carrying out the invention]

[0013] Preferred embodiments of the present invention are shown below. [1] The steel pipe pile of the present invention comprises a cylindrical pile body, a bit disposed inside the lower end of the pile body and protruding downward from the lower end of the pile body, two wings provided at the lower end of the pile body and extending radially outward from the outer surface of the pile body, and inclined to intersect each other with respect to the horizontal plane in a side view, and two upper support plates provided above each of the two wings inside the lower end of the pile body, and two slits formed at the lower end of the pile body for fitting the two wings, The bit is plate-shaped, traversing the pile body in the radial direction, with both ends in the radial direction welded to the inner circumferential surface of the pile body. The two wings are each fitted into the two slits and welded to the plate surface of the bit. The two upper support plates are plate-shaped, positioned perpendicular to the bit, with one of the ends perpendicular to the bit welded to the plate surface of the bit and the other welded to the center of the inclination direction of each of the two wings on the inner circumferential surface of the pile body. With this configuration, the portion of the pile body above each wing, located behind the lower end of each wing in the inclination direction of the steel pipe pile in the rotational direction, is prevented from deforming inward by the two upper support plates. Therefore, when the steel pipe pile is pressed into the ground, deformation of the portion of the pile body above each wing can be prevented.

[0014] [2] In the steel pipe pile described in [1] above, two lower support plates are provided inside the lower end of the pile body on the lower side of each of the two wings, and the two lower support plates are plate-shaped and arranged perpendicular to the bit, and both end faces perpendicular to the bit are welded and fixed to the plate surface of the bit and the inner circumferential surface of the pile body. With such a configuration, the lower end of the pile body is reinforced by the two lower support plates, so that deformation of the lower end of the pile body can be prevented more reliably.

[0015] [3] In the steel pipe pile described in [2] above, the two lower support plates may have a protruding portion that protrudes downward from the lower end of the pile body, and the protruding portion may have an inclined surface that slopes downward toward the radial center of the pile body. According to such a configuration, the ground directly below the pile body can be efficiently crushed by the bit and the two lower support plates, so that the jacking efficiency can be improved.

[0016] <Example 1> Hereinafter, Example 1 embodying the present invention will be described in detail with reference to FIGS. 1 to 6. FIG. 1 shows a perspective view of the lower end portion of the steel pipe pile P of Example 1. The steel pipe pile P includes a pile body 10 having a cylindrical shape, two blades 21 and 22 provided at the lower end portion of the pile body 10, one bit 30, two upper support plates 41 and 42, and two lower support plates 51 and 52. The pile body 10 is shown by a two-dot chain line in FIG. 1. The pile body 10, the blades 21 and 22, the bit 30, the upper support plates 41 and 42, and the lower support plates 51 and 52 are all made of steel. Hereinafter, one of the two blades 21 and 22 will be referred to as the first blade 21 and the other as the second blade 22.

[0017] In this embodiment, the case where the steel pipe pile P is a small-diameter steel pipe pile will be described. Specifically, the case where the diameter dimension of the pile body 10 is 114.3 mm, the thickness dimension of the steel material of the pile body 10 is 4.5 mm, the thickness dimensions of the first blade 21 and the second blade 22 are 12 mm, and the thickness dimensions of the bit 30, the upper support plates 41 and 42, and the lower support plates 51 and 52 are all 9 mm will be described. The various dimensions related to the steel pipe pile P may be appropriately set according to various conditions.

[0018] Hereinafter, in each component member, the vertical direction when the steel pipe pile P is jacked into the ground will be described as the up-down direction, the direction in which the bit 30 crosses the pile body 10 will be described as the front-back direction, and the direction orthogonal to the plate surface of the bit 30 will be described as the left-right direction. In each figure, the positive direction side of the X-axis is the front side, the negative direction side of the X-axis is the rear side, the positive direction side of the Y-axis is the upper side, the negative direction side of the Y-axis is the lower side, the positive direction side of the Z-axis is the left side, and the negative direction side of the Z-axis is the right side.

[0019] Figure 2 shows an exploded front view of the lower end of the steel pipe pile P. At the lower end of the pile body 10, two slits 11, 12 for fitting the first blade 21 and the second blade 22 are formed. Among the two slits 11, 12, the slit 11 for fitting the first blade 21 is referred to as the first slit 11, and the slit 12 for fitting the second blade 22 is referred to as the second slit 12.

[0020] The first slit 11 is formed in the left region of the pile body 10, and the second slit 12 is formed in the right region of the pile body 10. The first slit 11 and the second slit 12 are each inclined with respect to the horizontal plane (XZ plane). The inclination angles of the first slit 11 and the second slit 12 with respect to the horizontal plane are set to 15° in a side view. This inclination angle may be set within the range of 5° or more and 25° or less, and more preferably 10° or more and 20° or less. The lower end 11S of the first slit 11 and the lower end 12S of the second slit 12 are both located upward by a predetermined dimension from the lower end 10S of the pile body 10. Only the lower end 12S of the second slit 12 is shown in Figure 2.

[0021] The positional relationship between the first slit 11 and the second slit 12 will be described. At the front end of the pile body 10, a predetermined interval is provided in the vertical direction between the upper end 11U of the first slit 11 and the lower end 12S of the second slit 12. Also, an interval equivalent to the thickness dimension of the bit 30 is provided in the horizontal direction between the upper end 11U of the first slit 11 and the lower end 12S of the second slit 12. Similarly, at the rear end of the pile body 10, a predetermined interval in the vertical direction and an interval equivalent to the thickness dimension of the bit 30 in the horizontal direction are provided between the lower end 11S of the first slit 11 and the upper end 12U of the second slit 12.

[0022] The first blade 21 and the second blade 22 are fitted into the first slit 11 and the second slit 12 and are welded and fixed to the pile body 10. The first blade 21 and the second blade 22 are held in a state inclined with respect to the horizontal plane as shown in Figure 1. Specifically, the first blade 21 has an inclination rising from the rear side to the front side, and the second blade 22 has an inclination rising from the front side to the rear side.

[0023] Figure 3 shows a plan view of the steel pipe pile P. The first blade 21 and the second blade 22 have the same shape in plan view. The first blade 21 and the second blade 22 each have a linear surface 23 that extends in a straight line in plan view and an arc-shaped surface 24 that extends in an arc in plan view. The arc-shaped surface 24 of the first blade 21 and the arc-shaped surface 24 of the second blade 22 are located on the same circumference in plan view. In plan view, the diameter of the circle formed by the arc-shaped surface 24 of the first blade 21 and the arc-shaped surface 24 of the second blade 22 is set within the range of 1.5 to 3.5 times the outer diameter of the pile body 10, and in this embodiment it is set to 350 mm.

[0024] The front-to-back center of the straight surface 23 of the first blade 21 and the front-to-back center of the straight surface 23 of the second blade 22 are welded and fixed to the plate surface of the bit 30. This closes the lower end opening of the pile body 10.

[0025] The first blade 21 and the second blade 22 each have a portion positioned inside the pile body 10 and an overhanging portion 26 that extends outward from the outer circumferential surface of the pile body 10. The portions of the first blade 21 and the second blade 22 positioned inside the pile body 10 constitute a closing portion 25 that closes the lower end opening of the pile body 10. The closing portion 25 is approximately circular in plan view. The overhanging portion 26 of the first blade 21 and the overhanging portion 26 of the second blade 22 form an annular shape that surrounds the pile body 10 in plan view.

[0026] Figure 4 shows a side view of the lower end of the steel pipe pile P. In Figure 4, the pile body 10 is shown by a dashed line. The first blade 21 and the second blade 22 intersect each other at the position of the axis 10 of the steel pipe pile P in a side view. The inclination angle of the first blade 21 and the second blade 22 with respect to the horizontal plane is set to 15° in a side view. This inclination angle should be set within the range of 5° or more and 25° or less, and more preferably 10° or more and 20° or less.

[0027] A predetermined vertical gap is maintained between the upper end 21U of the first blade 21 in the inclined direction and the lower end 22S of the second blade 22 in the inclined direction, and between the lower end 21S of the first blade 21 in the inclined direction and the upper end 22U of the second blade 22 in the inclined direction, when viewed from the side. The lower end 21S of the first blade 21 is the part of the overhang 26 that is behind the rear end of the pile body 10. The lower end 22S of the second blade 22 is the part of the overhang 26 that is in front of the front end of the pile body 10. Both the lower end 21S of the first blade 21 and the lower end 22S of the second blade 22 extend below the lower end 10S of the pile body 10.

[0028] Blade portions 27 are formed at the lower end 21S of the first blade 21 and the lower end 22S of the first blade 22 (see Figures 1-3). The blade portions 27 are formed by cutting the upper surfaces of the lower end 21S of the first blade 21 and the lower end 22S of the second blade 22.

[0029] As shown in Figure 4, the bit 30 is located inside the pile body 10. In a side view, the bit 30 has a home plate shape. The bit 30 protrudes downward from the lower end 10S of the pile body 10. The bit 30 is plate-shaped and crosses the pile body 10 in the front-rear direction (radial direction of the pile body 10). The front and rear end faces (radial end faces) 30F and 30R of the bit 30 extend parallel to the axis 10L of the pile body 10. The lower ends of the front and rear end faces 30F and 30R of the bit 30 are located below the lower end 10S of the pile body 10.

[0030] The upper end surface 30U of the bit 30 is perpendicular to the axis 10L of the pile body 10. The upper end surface 30U of the bit 30 is located above the upper end 11U of the first slit 11 and the upper end 12U of the second slit 12.

[0031] The lower end surface 30S of the bit 30 has a pair of front and rear inclined portions 31. The front and rear inclined portions 31 slope downward from the lower ends of the front and rear end surfaces 30F and 30R of the bit 30 toward the center of the bit 30 in the front-rear direction. The lower end of the bit 30 is pointed and is located on the axis 10L of the pile body 10.

[0032] The front and rear end faces 30F and 30R of the bit 30 are welded to the inner circumferential surfaces of the front and rear ends of the pile body 10 (see Figure 3). Specifically, the front end face 30F of the bit 30 is welded to the pile body 10 at a position between the lower end 22S of the second blade 22 and the upper end 21U of the first blade 21. The rear end face 30R of the bit 30 is welded to the pile body 10 at a position between the lower end 21S of the first blade 21 and the upper end 22U of the second blade 22.

[0033] As shown in Figure 2, the two upper support plates 41 and 42 are identical in shape, and each is a rectangular plate that is longer in the left-right direction than in the up-down direction. The two upper support plates 41 and 42 are provided above the first wing 21 and the second wing 22, respectively. The upper support plate 41 provided above the first wing 21 is called the first upper support plate 41, and the upper support plate 42 provided above the second wing 22 is called the second upper support plate 42. In the steel pipe pile P, the first upper support plate 41 and the second upper support plate 42 are symmetrical with respect to the axis 10L (see Figure 5).

[0034] The first upper support plate 41 and the second upper support plate 42 are positioned perpendicular to the plate surface of the bit 30, as shown in Figure 3. One of the left and right end faces (end faces perpendicular to the bit 30) of the first upper support plate 41 and the second upper support plate 42 is welded to the plate surface of the bit 30, and the other end face is welded to the inner circumferential surface of the pile body 10.

[0035] Specifically, the right end face 41R of the first upper support plate 41 is welded and fixed to the center position in the front-rear direction of the left side of the plate surface of the bit 30, along its entire vertical length. The left end face 41L of the first upper support plate 41 is welded and fixed to the center position in the front-rear direction of the first wing 21 on the inner circumferential surface of the pile body 10, along its entire vertical length. The center position in the front-rear direction of the first wing 21 is the center position in the inclination direction of the first wing 21. The welding point between the left end face 41L of the first upper support plate 41 and the pile body 10 is located behind the lower end 21S of the first wing 21 in the rotation direction D when the steel pipe pile P is rotated and pressed into the ground.

[0036] The left end face 42L of the second upper support plate 42 is welded and fixed to the center position in the front-rear direction of the plate surface to the right of the bit 30, along its entire vertical length. The right end face 42R of the second upper support plate 42 is welded and fixed to the center position in the front-rear direction of the second wing 22 on the inner circumferential surface of the pile body 10, along its entire vertical length. The center position in the front-rear direction of the second wing 22 is the center position in the inclination direction of the second wing 22. The welding point between the right end face 42R of the second upper support plate 42 and the pile body 10 is located behind the lower end 22S of the second wing 22 in the rotation direction D.

[0037] Figure 5 shows a front view of the lower end of the steel pipe pile P. In Figure 5, the pile body 10 is shown by a dashed line. The lower end surface 41S of the first upper support plate 41 is welded to the upper surface of the first wing 21. The lower end surface 42S of the second upper support plate 42 is welded to the upper surface of the second wing 22. The lower end surface 41S of the first upper support plate 41 is inclined to match the inclination of the upper surface of the first wing 21, and the lower end surface 42S of the second upper support plate 42 is inclined to match the inclination of the upper surface of the second wing 22 (see Figure 4).

[0038] The two lower support plates 51 and 52, as shown in Figure 2, are identical in shape and are rectangular plates that are longer in the left-right direction than in the up-down direction. The two lower support plates 51 and 52 are provided on the underside of the first wing 21 and the second wing 22, respectively. The lower support plate 51 provided on the underside of the first wing 21 is called the first lower support plate 51, and the lower support plate 52 provided on the underside of the second wing 22 is called the second lower support plate 52. In the steel pipe pile P, the first lower support plate 51 and the second lower support plate 52 are symmetrical with respect to the axis 10L (see Figure 5).

[0039] Similar to the first upper support plate 41 and the second upper support plate 42, one of the left and right end faces (end faces perpendicular to the bit 30) of the first lower support plate 51 and the second lower support plate 52 is welded to the plate surface of the bit 30, and the other end face is welded to the inner circumferential surface of the pile body 10.

[0040] Specifically, the right end face 51R of the first lower support plate 51 is welded to the center position in the front-to-back direction of the plate surface to the left of the bit 30. The left end face 51L of the first lower support plate 51 is welded to the center position in the front-to-back direction of the first wing 21 on the inner circumferential surface of the pile body 10. The left end face 51L of the second lower support plate 52 is welded to the center position in the front-to-back direction of the plate surface to the right of the bit 30. The right end face 51R of the second lower support plate 52 is welded to the center position in the front-to-back direction of the second wing 22 on the inner circumferential surface of the pile body 10.

[0041] The upper end surface 51U of the first lower support plate 51 is welded to the lower surface of the first wing 21 (see Figure 4). The upper end surface 51U of the second lower support plate 52 is welded to the lower surface of the second wing 22. The upper end surface 51U of the first lower support plate 51 is inclined to match the inclination of the lower surface of the first wing 21, and the upper end surface 51U of the second lower support plate 52 is inclined to match the inclination of the lower surface of the second wing 22. The first lower support plate 51 and the second lower support plate 52 have protruding portions 53 that extend downward from the lower end 10S of the pile body 10 (see Figure 5).

[0042] Next, an example of the operation for rotary driving the steel pipe pile P of Example 1 into the ground will be described. When rotary driving the steel pipe pile P into the ground, the steel pipe pile P is rotated around the axis 10L while being pressed downwards by a construction device (not shown) (see Figure 6). The bit 30 excavates the ground vertically below the pile body 10 and pushes it back around the pile body 10. The first blade 21 and the second blade 22 bite into the ground around the pile body 10. In this way, the steel pipe pile P is gradually embedded in the ground.

[0043] When the steel pipe pile P is rotated and pressed into the ground, the first blade 21 and the second blade 22 receive an upward force F1 from the ground. In addition, the lower end 21S of the first blade 21 and the lower end 22S of the second blade 22 each receive a force F2 from the ground in the opposite direction of rotation. The forces F1 and F2 acting on the lower end 21S of the first blade 21 and the lower end 22S of the second blade 22 act on the upper blade portion 13 of the pile body 10. The upper blade portion 13 is the lower end of the pile body 10, above the first blade 21 and the second blade 22, respectively, and is located behind the lower end 21S of the first blade 21 in the direction of rotation D, and behind the lower end 22S of the second blade 22 in the direction of rotation D.

[0044] The force F3 acting on the upper part 13 of the blade is a force directed diagonally upward toward the rear in the rotational direction D. A large compressive force acts on the upper part 13 of the blade due to force F3, a downward force received from the construction device, and a forward force in the rotational direction D received from the construction device. In the case of conventional piles where only the bit 30 is provided at the lower end of the pile body 10, there is a risk that the upper part 13 of the blade may deform, such as being crushed inward, due to the compressive force. However, the steel pipe pile P is equipped not only with the bit 30 but also with a first upper support plate 41 and a second upper support plate 42, and the first upper support plate 41 and the second upper support plate 42 each support the inside of the upper part 13 of the blade, thus preventing deformation such as the upper part 13 of the blade being concave inward.

[0045] The embodiment configured as described above provides the following effects. The steel pipe pile P comprises a pile body 10, a bit 30, two blades 21 and 22, and two upper support plates 41 and 42. The pile body 10 is cylindrical in shape. The bit 30 is located inside the lower end of the pile body 10 and protrudes downward from the lower end 10S of the pile body 10. The two blades 21 and 22 are provided at the lower end of the pile body 10, protruding radially outward from the outer circumferential surface of the pile body 10, and are inclined to intersect each other with respect to the horizontal plane in a side view. The two upper support plates 41 and 42 are provided inside the lower end of the pile body 10, above the respective blades 21 and 22.

[0046] Two slits 11 and 12 are formed at the lower end of the pile body 10 for fitting two wings 21 and 22. The bit 30 is plate-shaped and crosses the pile body 10 in the front-to-back direction (radial direction), and both front and rear end faces (both end faces in the radial direction) 30F and 30R are welded and fixed to the inner circumferential surface of the pile body 10. The two wings 21 and 22 are each fitted into the two slits 11 and 12 and welded and fixed to the plate surface of the bit 30. The two upper support plates 41 and 42 are plate-shaped and are each positioned perpendicular to the bit 30.

[0047] Of the left and right end faces 41L and 41R of the first upper support plate 41 (the end faces in the direction perpendicular to the bit 30), the right end face 41R is welded to the plate surface of the bit 30, and the left end face 41L is welded to the center position in the front-rear direction (center position in the inclination direction) of the first wing 21 on the inner circumferential surface of the pile body 10. Of the left and right end faces 42L and 42R of the second upper support plate 42 (the end faces in the direction perpendicular to the bit 30), the left end face 42L is welded to the plate surface of the bit 30, and the right end face 42R is welded to the center position in the front-rear direction (center position in the inclination direction) of the second wing 22 on the inner circumferential surface of the pile body 10.

[0048] With this configuration, the upper part 13 of the wing of the pile body 10 is prevented from deforming inward by the two upper support plates 41 and 42, so that deformation of the upper part 13 of the wing of the pile body 10 can be prevented when the steel pipe pile P is pressed into the ground.

[0049] Furthermore, the steel pipe pile P is equipped with two lower support plates 51 and 52 located inside the lower end of the pile body 10, below each of the two wings 21 and 22. The two lower support plates 51 and 52 are plate-shaped and are arranged perpendicular to the bit 30. The left and right end faces 51L and 51R of the first lower support plate 51 (end faces in the direction perpendicular to the bit 30) are welded and fixed to the plate surface of the bit 30 and the inner circumferential surface of the pile body 10. The left and right end faces 52L and 52R of the second lower support plate 52 (end faces in the direction perpendicular to the bit 30) are welded and fixed to the plate surface of the bit 30 and the inner circumferential surface of the pile body 10. With this configuration, the lower end of the pile body 10 is reinforced by the two lower support plates 51 and 52, so deformation of the lower end of the pile body 10 can be prevented more reliably.

[0050] <Example 2> Next, a steel pipe pile 60 according to Embodiment 2, which embodies the present invention, will be described with reference to Figure 7. The steel pipe pile 60 of this embodiment differs from Embodiment 1 in that the protruding portions 53 of the two lower support plates 51 and 52 have inclined surfaces 61 that slope downward toward the center of the pile body 10. Components similar to those in Embodiment 1 are denoted by the same reference numerals, and redundant explanations are omitted.

[0051] The steel pipe pile 60 according to this embodiment comprises a pile body 10, a bit 30, a first blade 21 and a second blade 22, a first upper support plate 41 and a second upper support plate 42, a first lower support plate 51 and a second lower support plate 52, similar to the first embodiment.

[0052] The first lower support plate 51 and the second lower support plate 52 each have a protrusion 53, similar to Embodiment 1. The protrusion 53 of the first lower support plate 51 and the protrusion 53 of the second lower support plate 52 each have an inclined surface 61. In the steel pipe pile 60, the first lower support plate 51 and the second lower support plate 52 are symmetrical with respect to the axis 10L, similar to Embodiment 1. In a front view of the steel pipe pile 60, the first lower support plate 51 and the second lower support plate 52 form a home plate shape.

[0053] The inclined surface 61 of the first lower support plate 51 slopes downward from the lower end of the left end surface 51L to the lower end of the right end surface 51R of the first lower support plate 51. The vertical dimension of the right end surface 51R of the first lower support plate 51 is greater than the vertical dimension of the left end surface 51L of the second lower support plate 52.

[0054] The inclined surface 61 of the second lower support plate 52 slopes downward from the lower end of the right end surface 52R to the lower end of the left end surface 52L of the second lower support plate 52. The vertical dimension of the left end surface 52L of the second lower support plate 52 is greater than the vertical dimension of the right end surface 52R of the second lower support plate 52.

[0055] The lower end of the inclined surface 61 of the first lower support plate 51 and the lower end of the inclined surface 61 of the second lower support plate 52 are both located near the lower end of the bit 30. The upper end of the inclined surface 61 of the first lower support plate 51 and the upper end of the inclined surface 61 of the second lower support plate 52 are located below the lower end 10S of the pile body 10.

[0056] As described above, in this embodiment, similar to Embodiment 1, the deformation of the upper wing portion 13 of the pile body 10 can be prevented by the first upper support plate 41 and the second upper support plate 42. In addition, the protruding portions 53 of the two lower support plates 51 and 52 have an inclined surface 61 that slopes downward toward the center of the pile body 10. With this configuration, the steel pipe pile 60 can efficiently crush the ground directly beneath the pile body 10 with the bit 30 and the two lower support plates 51 and 52, thereby improving the driving efficiency.

[0057] <Other examples> The present invention is not limited to the embodiments described above and in the drawings, and the following embodiments, for example, are also included in the technical scope of the present invention. (1) In the above embodiment, the steel pipe pile P(60) is equipped with a first upper support plate 41 and a second upper support plate 42, but additional upper support plates may be added. For example, multiple additional upper support plates may be arranged radially around the axis of the pile body, or multiple upper support plates may be arranged in a direction perpendicular to the plate surface of the bit 30, similar to the first upper support plate 41 and the second upper support plate 42. [Explanation of Symbols]

[0058] 10…Stake body 10S...Lower end of the pile body 11, 12… Two slits 21, 22… Two feathers 30...bit 30F, 30R... Front and rear end faces (both end faces in the radial direction) 41, 42… Two upper support plates 41L, 41R... Both end faces (the end faces perpendicular to the bit) 51, 52… Two lower support plates 51L, 51R... Both end faces (the end faces perpendicular to the bit) 53…protrusion 61… Inclined surface P,60…steel pipe Hangzhou

Claims

1. The pile body is cylindrical in shape, A bit is positioned inside the lower end of the pile body and protrudes downward from the lower end of the pile body, Two wings are provided at the lower end of the pile body, protruding radially outward from the outer circumferential surface of the pile body, and inclined to intersect each other with respect to the horizontal plane in a side view, The pile body comprises two upper support plates provided on the upper side of each of the two wings inside the lower end of the pile body, The lower end of the pile body has two slits formed therein for fitting the two wings. The bit is plate-shaped and extends radially across the pile body, with both ends in the radial direction welded and fixed to the inner circumferential surface of the pile body. The two blades are each fitted into the two slits and welded to the plate surface of the bit. The two upper support plates are plate-shaped and arranged perpendicular to the bit. One of the end faces perpendicular to the bit is welded to the plate surface of the bit, and the other end is welded to the center of the inclination direction of each of the two wings on the inner circumferential surface of the pile body. A steel pipe pile characterized by the following features.

2. The lower end of the pile body is provided with two lower support plates located below each of the two wings, The two lower support plates are each plate-shaped and positioned perpendicular to the bit, and both end faces perpendicular to the bit are welded and fixed to the plate surface of the bit and the inner circumferential surface of the pile body. The steel pipe pile according to feature 1.

3. The two lower support plates each have a projection that extends downward from the lower end of the pile body, and the projection has an inclined surface that slopes downward toward the radial center of the pile body. The steel pipe pile according to feature 2.

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