steel pipe Hangzhou

Abstract

To obtain a steel pipe pile that can be easily driven into the ground. [Solution] This steel pipe pile comprises a main shaft 1 and a tip member 2 provided on the main shaft 1. The tip member 2 is provided at one end of the axial direction D1 of the main shaft 1 and has a dome portion 21 whose outer peripheral surface 211 is curved so as it approaches the axis AL of the main shaft 1, and two drilling blades 22 provided on the inner and outer portions of the outer peripheral surface 211 of the dome portion 21, and arranged so as to be point-symmetric with respect to the axis AL when viewed along the axis AL. Each of the two drilling blades 22 is positioned away from the axis AL.

Description

Technical Field

[0005] , , ,

[0001] This invention relates to steel pipe piles.

Background Art

[0002] Conventionally, a steel pipe pile having a main shaft and a tip member provided on the main shaft is known. The shape of the main shaft is formed in a cylindrical shape. The tip member has a closing portion provided at one end in the axial direction of the main shaft and two excavation blades provided on the closing portion. The shape of the closing portion is formed in a disc shape. The closing portion closes the opening of the main shaft. The shape of each excavation blade is formed in a flat semi-circular shape.

[0003] The two excavation blades are provided across the inner portion and the outer portion in the radial direction in the closing portion. The two excavation blades are arranged such that the convex surface faces the rotation direction side of the main shaft. The two excavation blades are arranged to be point-symmetrical about the axis of the main shaft when viewed along the axis of the main shaft. The two excavation blades are connected to each other on the axis of the main shaft (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the configuration of the steel pipe pile described in Patent Document 1, the shape of the closing portion is formed in a disc shape, and the respective excavation blades are connected to each other on the axis of the main shaft. As a result, when the steel pipe pile is pushed into the ground while rotating, the earth and sand below the steel pipe pile and on the axis of the main shaft is pushed downward without moving radially outward. As a result, there is a problem that a large force is required to push the steel pipe pile into the ground.

[0006] This invention was made to solve the above-mentioned problems, and its purpose is to provide a steel pipe pile that can be easily driven into the ground. [Means for solving the problem]

[0007] The steel pipe pile according to this invention comprises a main shaft and a tip member provided on the main shaft, the tip member having a dome portion provided at one end of the main shaft in the axial direction and whose outer surface is curved so as it approaches the axis of the main shaft, and two drilling blades provided across the radially inner and radially outer portions of the outer surface of the dome portion and arranged so as to be point-symmetric with respect to the axis when viewed along the axis, each of the two drilling blades is positioned away from the axis. In the steel pipe pile according to this invention, the shape of each of the two drilling blades is curved such that, when viewed along the axis, the convex surface faces the direction of rotation of the main axis. In the steel pipe pile according to this invention, the shape of the convex surface of each of the two drilling blades has a constant radius of curvature. In the steel pipe pile according to this invention, the shape of the convex surface of each of the two drilling blades is formed along a clothoid curve in which the radius of curvature decreases at a constant rate as it moves radially outward. In the steel pipe pile according to this invention, the shape of each of the two drilling blades is formed such that the amount of protrusion from the outer surface of the dome increases as it moves toward the rotational direction of the main shaft. In the steel pipe pile according to this invention, the shape of each of the two drilling blades is formed such that the amount of protrusion from the outer surface of the dome increases as it moves radially inward. In the steel pipe pile according to this invention, the shape of each of the two drilling blades is such that, when viewed along the axis, the thickness dimension in the longitudinal direction is constant at least in the middle portion, regardless of the position in the longitudinal direction. [Effects of the Invention]

[0008] According to the steel pipe pile of this invention, the steel pipe pile can be easily driven into the ground. [Brief explanation of the drawing]

[0009] [Figure 1] This is a front view showing a steel pipe pile according to Embodiment 1. [Figure 2] Figure 1 is a bottom view showing the steel pipe pile. [Figure 3] This is a cross-sectional view taken along the line III-III in Figure 2. [Figure 4] This figure shows the dome section and excavation blade after the steel pipe pile according to Embodiment 1 has been driven into the ground. [Figure 5] This figure shows the dome section and drilling blade after the comparative example steel pipe pile has been driven into the ground. [Figure 6] This is a bottom view showing a steel pipe pile according to Embodiment 2. [Modes for carrying out the invention]

[0010] Embodiment 1. Figure 1 is a front view showing a steel pipe pile according to Embodiment 1. Figure 2 is a bottom view showing the steel pipe pile of Figure 1. Figure 3 is a cross-sectional view taken along the line III-III in Figure 2. The steel pipe pile according to Embodiment 1 comprises a main shaft 1 and a tip member 2.

[0011] The shape of the main spindle 1 is cylindrical. The direction along the axis AL of the main spindle 1 is defined as the axial direction D1. The direction along the radius of the circle centered on the axis AL of the main spindle 1 in a plane perpendicular to the axis AL of the main spindle 1 is defined as the radial direction D2. The direction along the circumference of the circle centered on the axis AL of the main spindle 1 in a plane perpendicular to the axis AL of the main spindle 1 is defined as the circumferential direction D3.

[0012] In the steel pipe pile according to Embodiment 1, the outer diameter of the main shaft 1, when viewed along the axial direction D1, is within the range of φ101.6 mm to φ609.6 mm.

[0013] The tip member 2 is provided at one end of the main shaft 1 in the axial direction D1. The tip member 2 closes the opening of the main shaft 1. The tip member 2 is fixed to the main shaft 1 by welding.

[0014] The tip member 2 has a dome portion 21 and two cutting blades 22. The number of the cutting blades 22 is only two.

[0015] The dome portion 21 is fixed to the main shaft 1 by welding. The dome portion 21 closes a circular opening formed at one end of the main shaft 1 in the axial direction D1. The shape of the dome portion 21 is formed such that the outer peripheral surface 211 curves away from the main shaft 1 as it approaches the axis AL of the main shaft 1.

[0016] Each cutting blade 22 is provided across the inner portion and the outer portion in the radial direction D2 on the outer peripheral surface 211 of the dome portion 21. Each cutting blade 22 protrudes from the outer peripheral surface 211 of the dome portion 21 to one side in the axial direction D1. One side in the axial direction D1 is the downward direction when pressing the steel pipe pile against the ground.

[0017] When viewed along the axis AL, the two cutting blades 22 are arranged symmetrically with respect to the axis AL.

[0018] Each cutting blade 22 is arranged away from the axis AL. Therefore, the portion of the outer peripheral surface 211 of the dome portion 21 on the axis AL is exposed.

[0019] <I The two cutting blades 22 are arranged apart from each other. Therefore, when pushing the steel pipe pile into the ground while rotating it, the tip member 2 can cut the ground more efficiently compared to the case where the two cutting blades 22 are connected to each other.

[0020] The shape of each drilling blade 22 is curved such that, when viewed along the axis AL, the convex surface 221 faces the rotational direction RD of the main shaft 1. Therefore, when the steel pipe pile is driven into the ground while rotating, each drilling blade 22 can efficiently cut through the hard ground and move the soil outward in the radial direction D2.

[0021] The shape of each convex surface 221 of each drilling blade 22 has a constant radius of curvature. Therefore, each drilling blade 22 can be easily manufactured.

[0022] The shape of each drilling blade 22 is formed such that the amount of protrusion from the outer surface 211 of the dome portion 21 increases as it moves toward the rotation direction RD of the main shaft 1. In other words, the amount of protrusion PA1 of each drilling blade 22 from the outer surface 211 of the dome portion 21 in the forward part of the rotation direction RD of the main shaft 1 is greater than the amount of protrusion PA2 of each drilling blade 22 from the outer surface 211 of the dome portion 21 in the rear part of the rotation direction RD of the main shaft 1. Therefore, when the steel pipe pile is driven into the ground while rotating, each drilling blade 22 can cut through hard ground more efficiently.

[0023] The shape of each drilling blade 22 is formed such that the amount of protrusion from the outer surface 211 of the dome portion 21 increases as it moves inward in the radial direction D2. In other words, the amount of protrusion PA3 from the outer surface 211 of the dome portion 21 in the inner part of the radial direction D2 of each drilling blade 22 is greater than the amount of protrusion PA4 from the outer surface 211 of the dome portion 21 in the outer part of the radial direction D2. This allows the ground to be excavated from the inner part of the radial direction D2 of each drilling blade 22 when the steel pipe pile is driven into the ground while rotating. Therefore, each drilling blade 22 can excavate hard ground more efficiently.

[0024] The shape of each drilling blade 22 is such that, when viewed along the axis AL, the thickness dimension in the longitudinal direction is constant at least in the middle portion, regardless of its position in the longitudinal direction. Therefore, each drilling blade 22 can be easily manufactured.

[0025] The outer end of each drilling blade 22 in the radial direction D2 extends to the outer edge portion of the outer circumferential surface 211 of the dome portion 21. Therefore, the area over which the ground is excavated by the drilling blade 22 can be increased.

[0026] The tip member 2 is a casting that is integrally formed by casting. In other words, the dome portion 21 and the two drilling blades 22 are both integrally formed by casting.

[0027] Next, the procedure for driving the steel pipe pile according to Embodiment 1 into the ground will be described. When driving the steel pipe pile into the ground, the tip member 2 is pointed downwards and the steel pipe pile is driven into the ground while rotating the steel pipe pile in the rotational direction RD. As a result, the ground is excavated by the drilling blade 22 and the steel pipe pile moves downwards.

[0028] Soil below the steel pipe pile and on the axis AL of the main shaft 1 moves outward in the radial direction D2 along the outer surface 211 of the dome section 21, and then moves outward in the radial direction D2 along the two excavation blades 22. This allows the steel pipe pile to be easily driven into the ground.

[0029] Next, we will describe how the soil below the steel pipe pile and on the axis AL of the main shaft 1 moves outward in the radial direction D2 along the outer surface 211 of the dome portion 21, in each case where there are two or four drilling blades 22. Figure 4 shows the dome portion 21 and drilling blades 22 after the steel pipe pile according to Embodiment 1 has been driven into the ground. Figure 5 shows the dome portion 21 and drilling blades 22 after the steel pipe pile of a comparative example has been driven into the ground. In Figures 4 and 5, only the number of drilling blades 22 is different; all other conditions are the same.

[0030] In both the steel pipe pile according to Embodiment 1 and the steel pipe pile of the comparative example, black paint BP is applied to the outer surface 211 of the dome portion 21 before it is driven into the ground. When a certain amount of force is applied to the soil in contact with the outer surface 211, causing it to move outward in the radial direction D2, the black paint BP peels off from the outer surface 211. In Figures 4 and 5, the black paint BP that remains attached to the outer surface 211 without peeling off is shown as a mesh pattern.

[0031] In the steel pipe pile according to Embodiment 1, which has two excavation blades 22, the amount of black paint BP that remains attached to the outer surface 211 without peeling off is less compared to the steel pipe pile of the comparative example, which has four excavation blades 22. Therefore, in the steel pipe pile according to Embodiment 1, more soil can be moved outward in the radial direction D2 on the outer surface 211 compared to the steel pipe pile of the comparative example.

[0032] Although Figures 4 and 5 show that the black paint BP on the axis AL on the outer surface 211 remains attached without peeling off, this only indicates that the steel pipe pile according to Embodiment 1 can move soil and sand outward in the radial direction D2 along the outer surface 211 more effectively than the steel pipe pile of the comparative example, and does not indicate that soil and sand on the axis AL on the outer surface 211 cannot move outward in the radial direction D2 along the outer surface 211.

[0033] As described above, the steel pipe pile according to Embodiment 1 comprises a main shaft 1 and a tip member 2 provided on the main shaft 1. The tip member 2 has a dome portion 21 and two drilling blades 22. The dome portion 21 is provided at one end of the axial direction D1 of the main shaft 1, and its outer circumferential surface 211 is curved so as it approaches the axis AL of the main shaft 1 and moves away from the main shaft 1. The two drilling blades 22 are provided across the inner portion and the outer portion of the outer circumferential surface 211 of the dome portion 21 in the radial direction D2, and are arranged so as to be point-symmetric with respect to the axis AL when viewed along the axis AL. Each of the two drilling blades 22 is positioned away from the axis AL. With this configuration, each drilling blade 22 is not positioned on the axis AL of the main shaft 1. As a result, when the steel pipe pile is driven into the ground while rotating, the soil below the steel pipe pile and on the axis AL of the main shaft 1 moves outward in the radial direction D2 along the outer surface 211 of the dome section 21. Consequently, the steel pipe pile can be easily driven into the ground.

[0034] Furthermore, in the steel pipe pile according to Embodiment 1, the shape of each of the two drilling blades 22 is curved such that, when viewed along the axis AL, the convex surface 221 faces the rotation direction RD of the main shaft 1. With this configuration, when the steel pipe pile is driven into the ground while rotating, each drilling blade 22 can more efficiently excavate hard ground.

[0035] Furthermore, in the steel pipe pile according to Embodiment 1, the shape of the convex surface 221 of each of the two drilling blades 22 has a constant radius of curvature. With this configuration, each drilling blade 22 can be easily manufactured.

[0036] Furthermore, in the steel pipe pile according to Embodiment 1, the shape of each of the two drilling blades 22 is formed such that the amount of protrusion from the outer surface 211 of the dome portion 21 increases as it moves toward the RD side in the rotation direction of the main shaft 1. With this configuration, when the steel pipe pile is driven into the ground while rotating, each drilling blade 22 can more efficiently excavate hard ground.

[0037] Furthermore, in the steel pipe pile according to Embodiment 1, the shape of each of the two drilling blades 22 is formed such that the amount of protrusion from the outer surface 211 of the dome portion 21 increases as it moves inward in the radial direction D2. With this configuration, when the steel pipe pile is driven into the ground while rotating, the ground can be excavated from the inner portion of each drilling blade 22 in the radial direction D2. Therefore, each drilling blade 22 can excavate hard ground more efficiently.

[0038] Furthermore, in the steel pipe pile according to Embodiment 1, the shape of each of the two drilling blades 22 is such that, when viewed along the axis AL, the thickness dimension in the longitudinal direction is constant at least in the middle portion, regardless of the position in the longitudinal direction. With this configuration, each drilling blade 22 can be easily manufactured.

[0039] Embodiment 2. Figure 6 is a bottom view showing a steel pipe pile according to Embodiment 2. In the steel pipe pile according to Embodiment 2, the shape of each convex surface 221 of the two drilling blades 22 is formed along a clothoid curve in which the radius of curvature decreases at a constant rate as it moves outward in the radial direction D2. Therefore, when the steel pipe pile is driven into the ground while rotating, each drilling blade 22 can more efficiently excavate hard ground.

[0040] The other configurations of the steel pipe pile according to Embodiment 2 are the same as those of the steel pipe pile according to Embodiment 1.

[0041] As described above, in the steel pipe pile according to Embodiment 2, the shape of each convex surface 221 of the two drilling blades 22 is formed along a clothoid curve in which the radius of curvature decreases at a constant rate as it moves outward in the radial direction D2. With this configuration, when the steel pipe pile is driven into the ground while rotating, the force with which each drilling blade 22 pushes the soil outward in the radial direction D2 increases as it moves outward in the radial direction D2. As a result, each drilling blade 22 can excavate hard ground more efficiently.

[0042] In each embodiment of the steel pipe pile, the configuration described is one in which the tip member 2 is fixed to the main shaft 1 by welding. However, the configuration is not limited to this. For example, the entire main shaft 1 and tip member 2 may be made of a casting that is integrally formed by casting.

[0043] Although preferred embodiments of steel pipe piles have been described above, the steel pipe piles are not limited to those embodiments described above. Various modifications and transformations can be made to the steel pipe piles according to the embodiments described above without departing from the scope of the claims.

[0044] The various aspects of this disclosure are summarized below as an appendix.

[0045] (Note 1) The main shaft, The tip member provided on the main shaft, Equipped with, The aforementioned tip member is A dome-shaped portion is provided at one end of the main spindle in the axial direction, and its outer surface is curved so as it approaches the axis of the main spindle, Two drilling blades are provided across the radially inner portion and the radially outer portion of the outer surface of the dome portion, and are arranged so as to be point-symmetric with respect to the axis when viewed along the axis, It has, Each of the two drilling blades is a steel pipe pile positioned away from the axis. (Note 2) The steel pipe pile described in Appendix 1, wherein the shape of each of the two drilling blades is curved such that, when viewed along the axis, the convex surface faces the direction of rotation of the main shaft. (Note 3) The shape of the convex surface of each of the two excavation blades is a steel pipe pile as described in Appendix 2, wherein the radius of curvature is constant. (Note 4) The steel pipe pile described in Appendix 2, wherein the shape of the convex surface of each of the two drilling blades is formed along a clothoid curve in which the radius of curvature decreases at a constant rate as it moves radially outward. (Note 5) The steel pipe pile according to any one of the appendices 1 to 4, wherein the shape of each of the two drilling blades is formed such that the amount of protrusion from the outer surface of the dome portion increases as it moves toward the rotational direction of the main shaft. (Note 6) The steel pipe pile according to any one of claims 1 to 5, wherein the shape of each of the two drilling blades is formed such that the amount of protrusion from the outer surface of the dome portion increases as it moves inward in the radial direction. (Note 7) The steel pipe pile according to any one of the appendices 1 to 6, wherein the shape of each of the two drilling blades is such that, when viewed along the axis, the thickness dimension at least in the middle of the longitudinal direction is constant regardless of the position in the longitudinal direction. [Explanation of symbols]

[0046] 1 Main shaft, 2 Tip member, 21 Dome section, 22 Excavation blade, 211 Outer surface, 221 Convex surface.

Claims

1. The main shaft, The tip member provided on the main shaft, Equipped with, The aforementioned tip member is A dome-shaped portion is provided at one end of the main spindle in the axial direction, and its outer surface is curved so as it approaches the axis of the main spindle, Two drilling blades are provided across the radially inner portion and the radially outer portion of the outer surface of the dome portion, and are arranged so as to be point-symmetric with respect to the axis when viewed along the axis, It has, Each of the two drilling blades is a steel pipe pile positioned away from the axis.

2. The steel pipe pile according to claim 1, wherein the shape of each of the two drilling blades is curved such that, when viewed along the axis, the convex surface faces the direction of rotation of the main shaft.

3. The steel pipe pile according to claim 2, wherein the shape of the convex surface of each of the two excavation blades has a constant radius of curvature.

4. The steel pipe pile according to claim 2, wherein the shape of the convex surface of each of the two drilling blades is formed along a clothoid curve in which the radius of curvature decreases at a constant rate as it moves outward in the radial direction.

5. The steel pipe pile according to any one of claims 1 to 4, wherein the shape of each of the two drilling blades is formed such that the amount of protrusion from the outer surface of the dome portion increases as it moves toward the rotational direction of the main shaft.

6. The steel pipe pile according to any one of claims 1 to 4, wherein the shape of each of the two drilling blades is formed such that the amount of protrusion from the outer surface of the dome portion increases as it moves inward in the radial direction.

7. The steel pipe pile according to any one of claims 1 to 4, wherein the shape of each of the two drilling blades is such that, when viewed along the axis, the thickness dimension in the middle portion in the longitudinal direction is constant regardless of the position in the longitudinal direction.

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