Steel pipe pile

Abstract

To provide a steel pipe pile capable of suppressing impairment of penetration ability.SOLUTION: A steel pipe pile is provided in which, when an opening area of an open portion between a first blade portion and a first imaginary plane is defined as a first opening area, and an opening area of the open portion between a second blade portion and the first imaginary plane is defined as a second opening area, the first imaginary plane is perpendicular to a central axis of a steel pipe and passes through a central height position between a first end and a second tip, and the second opening area is larger than the first opening area.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Various techniques have been proposed for applying a rotational force to a steel pipe pile having a wing portion at the tip of the steel pipe and penetrating it into the ground (for example, Patent Document 1). The configuration of the wing portion includes, for example, a spiral shape and a flat plate shape. In either shape, the thickness of the wing portion is usually constant. By making the wing portion spiral, it becomes easier to ensure a stable propulsion force of the wing portion, and by making the wing portion flat plate-shaped, it becomes easier to suppress the processing cost of the wing portion.

[0003] The wing portion may be inclined with respect to the steel pipe. At this time, by reducing the inclination angle (excavation angle), the resistance in excavation can be reduced.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] An opening is formed in the steel pipe for taking in the material to be excavated (for example, earth and sand) into the steel pipe. The formation region of the opening is defined by the wing portion. However, if the inclination angle of the wing portion is suppressed, the area of the formation region is suppressed accordingly, making it difficult for the material to be excavated to be taken into the steel pipe, and there is a possibility that the penetrability of the steel pipe pile is impaired.

[0006] The present invention has been made in view of such circumstances, and an object thereof is to provide a steel pipe pile capable of suppressing impairment of penetrability.

Means for Solving the Problems

[0007] [1] According to the present invention, there is provided a steel pipe pile having an excavation part at the tip of a steel pipe, wherein the excavation part is provided with an opening part for taking in an object to be excavated into the steel pipe, the excavation part has flat plate-shaped first and second wing parts adjacent to each other, the first wing part is connected to a first steel pipe edge part among the steel pipe edge parts of the tip surface of the steel pipe, the second wing part is connected to a second steel pipe edge part which is a part connected to the steel pipe edge part, in the central axis direction of the steel pipe, the first steel pipe edge part extends away from the tip of the steel pipe as it goes from a first tip of the first steel pipe edge part to a first terminal of the first steel pipe edge part, in the central axis direction of the steel pipe, the second steel pipe edge part extends away from the tip of the steel pipe as it goes from a second tip of the second steel pipe edge part to a second terminal of the second steel pipe edge part, in the central axis direction of the steel pipe, the distance between the second tip and the tip of the steel pipe is larger than the distance between the first tip and the tip of the steel pipe, when the opening area of the opening part between the first wing part and a first virtual plane is defined as a first opening area, and the opening area of the opening part between the second wing part and the first virtual plane is defined as a second opening area, the first virtual plane is orthogonal to the central axis of the steel pipe and passes through a central height position between the first terminal and the second tip, and a steel pipe pile is provided in which the second opening area is larger than the first opening area.

[0008] In the present invention, for example, even if the inclination angle of the first wing part is suppressed from the viewpoint of reducing resistance in excavation, since the second opening area is ensured to be larger than the first opening area, the penetration performance is suppressed from being impaired.

[0009] Hereinafter, various embodiments of the present invention will be exemplified. The embodiments shown below can be combined with each other.

[0010] [2] Preferably, there is provided a steel pipe pile as described in [1], wherein when the angle formed by the first wing part and the first virtual plane is defined as a first inclination angle, and the angle formed by the second wing part and the first virtual plane is defined as a second inclination angle, the second inclination angle is larger than the first inclination angle. [3] Preferably, the steel pipe pile according to [2], wherein the first inclination angle is 2 degrees or more and 20 degrees or less, and the second inclination angle is 3 degrees or more and 30 degrees or less, is provided. [4] Preferably, the steel pipe pile according to any one of claims 1 to 3, further comprising a reinforcing member, wherein the reinforcing member is provided in the opening portion along the inner surface of the steel pipe, and the reinforcing member is formed to taper in a cross section parallel to the first virtual plane. A steel pipe pile is provided. [5] Preferably, in the steel pipe pile according to any one of [1] to [4], when the excavation portion is viewed from the central axis direction of the steel pipe, a circular region is defined with the position of the central axis as the center and the distance between the center and the farthest position as the radius. The farthest position is the position of the portion of the excavation portion that is farthest from the central axis of the steel pipe, and when the excavation portion is viewed from the central axis direction of the steel pipe, the range where the excavation portion is provided is 70% or more of the total area of the circular region. A steel pipe pile is provided. [6] Preferably, in the steel pipe pile according to any one of [1] to [5], when the space is divided into first and second divided spaces by a second virtual plane passing through the central axis of the steel pipe, the first wing portion is disposed in the first divided space, and at least a part of the second wing portion is disposed in the second divided space. A steel pipe pile is provided. [7] Preferably, in the steel pipe pile according to any one of [1] to [6], the excavation portion includes three or more wing portions, and at least two adjacent wing portions among the plurality of wing portions are the first wing portion and the second wing portion. A steel pipe pile is provided. [8] Preferably, in the steel pipe pile according to any one of [1] to [7], the edge of the first wing portion has a tapered shape. A steel pipe pile is provided.

Brief Description of the Drawings

[0011]

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Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The various characteristic matters shown in the following embodiments can be combined with each other. Also, an invention can be established independently for each characteristic matter.

[0013] 1. First Embodiment 1-1. Explanation of the Configuration of the First Embodiment The steel pipe pile 100 shown in FIGS. 1A to 3B is a pile used in a rotary construction method of screwing into the ground in construction work. The steel pipe pile 100 is given a rotational force by a construction machine (not shown) deployed on the ground and is penetrated into the ground. A drilling portion 30, which will be described later and has a shape suitable for drilling, is provided at the tip portion 1a of the steel pipe pile 100, making it easier to screw the steel pipe pile 100 into the ground.

[0014] As shown in FIGS. 1A to 3B, the steel pipe pile 100 includes a steel pipe 10, an open portion 20, and a drilling portion 30.

[0015] 1-1-1. Steel Pipe 10 As shown in Fig. 4A, the steel pipe 10 is a hollow steel tube with both ends open, and the cross-section perpendicular to the central axis C of the steel pipe 10 is circular. As shown in Figs. 1A to 3B, the steel pipe 10 has a tip portion 1a that is screwed into the ground, and an opening portion 20 and an excavation portion 30 are provided at the tip portion 1a.

[0016] As shown in Fig. 4A, the tip portion 1a has a tip surface 1b, an inner surface 1c, and an outer surface 1d. As shown in Fig. 4C, on the tip surface 1b, a steel pipe edge portion 1e that is a portion connected to the excavation portion 30 and a longitudinal edge portion 1f extending in the direction of the central axis C of the steel pipe 10 are formed.

[0017] As shown in Figs. 4A to 4C, the steel pipe edge portion 1e has a first steel pipe edge portion 1e1 and a second steel pipe edge portion 1e2. The steel pipe edge portion 1e extends in a spiral or substantially spiral shape in the circumferential direction of the steel pipe 10. In other words, the first steel pipe edge portion 1e1 extends so as to form a part of a spiral, and similarly, the second steel pipe edge portion 1e2 extends so as to form a part of a spiral. In the first embodiment, the first steel pipe edge portion 1e1 and the second steel pipe edge portion 1e2 are independent (separated), but they may be connected. Here, the configuration of the steel pipe edge portion 1e will be specifically described.

[0018] As shown in Fig. 4C, the first steel pipe edge portion 1e1 has a first tip 1e11 and a first terminal 1e12. The first steel pipe edge portion 1e1 extends away from the tip tp of the steel pipe 10 as it goes from the first tip 1e11 to the first terminal 1e12 in the direction of the central axis C of the steel pipe 10. In the embodiment, the tip tp of the steel pipe 10 and the first tip 1e11 of the first steel pipe edge portion 1e1 coincide, but they do not have to coincide. Also, as shown in Fig. 4C, the second steel pipe edge portion 1e2 has a second tip 1e21 and a second terminal 1e22. The second steel pipe edge portion 1e2 extends away from the tip tp of the steel pipe 10 as it goes from the second tip 1e21 to the second terminal 1e22 in the direction of the central axis C of the steel pipe 10. Also, as shown in FIG. 4B, in the direction of the central axis C of the steel pipe 10, the distance d2 between the second tip 1e21 and the tip tp of the steel pipe 10 is larger than the distance d1 between the first tip 1e11 and the tip tp of the steel pipe 10. In the first embodiment, since the position of the first tip 1e11 of the steel pipe 10 coincides with the position of the tip tp of the steel pipe 10, the distance d1 is 0.

[0019] As shown in FIG. 4C, in the first embodiment, the longitudinal edge portion 1f extends parallel to the central axis C direction. Note that the longitudinal edge portion 1f is not limited to extending parallel to the central axis C direction. For example, depending on the shape of the steel pipe edge portion 1e, the extending direction may be deviated from the central axis C direction.

[0020] Specifically, for example, the outer diameter (mm) of the steel pipe 10 is 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, and it may be within the range between any two of the values exemplified here.

[0021] Specifically, for example, the wall thickness (mm) of the steel pipe 10 is 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 24, 26, 28, 30, and it may be within the range between any two of the values exemplified here.

[0022] Specifically, for example, the length (m) of the steel pipe 10 in the direction of the central axis C is 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, and it may be within the range between any two of the values exemplified here.

[0023] 1-1-2. Open portion 20 The opening 20 shown in FIGS. 1A to 3B is configured to take in the material to be excavated (e.g., earth and sand, etc.) into the steel pipe 10, and the opening 20 is defined by the steel pipe 10 and the excavation part 30. Specifically, as shown in FIG. 3A, the opening 20 has a trapezoidal opening defined by a wing part 3 (a first wing part 3a and a second wing part 3b) described later and a pair of vertical edge parts 1f. As the steel pipe pile 100 rotates, the material to be excavated is taken into the steel pipe 10 through the opening of the opening 20, and the steel pipe pile 100 penetrates into the ground.

[0024] 1-1-3. Excavation part 30 As shown in FIGS. 3A and 3B, the excavation part 30 has a wing part 3. In the first embodiment, the wing part 3 is composed of a plurality (two in the first embodiment) of independent wing parts (a first wing part 3a and a second wing part 3b). Note that although the number of wing parts is described as two, it is not limited to this, and the steel pipe pile 100 may have a form with three or more independent wing parts. The plurality of independent wing parts are flat plate-like members adjacent to each other. Each wing part is provided so as to be inclined when the steel pipe pile 100 is viewed from the side.

[0025] 1-1-3-1. First wing part 3a As shown in FIGS. 3A and 3B, the first wing part 3a has a first plate-like part 3c1 and a second plate-like part 3c2 that are overlapped. In the first embodiment, each wing part 3 (the first wing part 3a and the second wing part 3b) is composed of plate-like parts stacked in two layers.

[0026] <The first plate-like part 3c1 of the first wing part 3a> As shown in FIGS. 5A to 6, the first plate-like part 3c1 is a flat plate extending in an arc shape, and has a function as a reinforcing plate that suppresses the wing part 3 from being damaged, etc. due to the moment applied to the wing part 3 during construction.

[0027] As shown in FIGS. 5B and 6, the first plate-like part 3c1 has an outer edge part 3c11 and an inner edge part 3c12. The outer edge portion 3c11 is disposed outside the connecting portion between the first plate-like portion 3c1 and the steel pipe edge portion 1e (the first steel pipe edge portion 1e1) in the radial direction of the steel pipe 10 (the radial direction of the first wing portion 3a). The inner edge portion 3c12 is disposed inside the connecting portion between the first plate-like portion 3c1 and the steel pipe edge portion 1e (the first steel pipe edge portion 1e1) in the radial direction of the steel pipe 10 (the radial direction of the first wing portion 3a). The outer edge portion 3c11 and the inner edge portion 3c12 extend in an arc shape (circular arc shape in the first embodiment).

[0028] The first plate-like portion 3c1 is disposed inside the second plate-like portion 3c2 when viewed in plan. In other words, the first plate-like portion 3c1 is disposed so as not to protrude outside the edge of the second plate-like portion 3c2. In the first embodiment, the edge of the second plate-like portion 3c2 is composed of a portion extending in an arc shape with a central angle of 180 degrees and a portion extending linearly through the center. Also, the position of the peripheral edge of the first plate-like portion 3c1 and the inside of the second plate-like portion 3c2 may coincide.

[0029] The first plate-like portion 3c1 has a central angle (degrees) of 180 degrees in plan view. Note that the central angle is not limited to this, and specifically, for example, it is 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, and it may be within the range between any two of the numerical values exemplified here.

[0030] The first plate-like portion 3c1 is connected to the steel pipe edge portion 1e (the first steel pipe edge portion 1e1) of the front end face 1b of the steel pipe 10 in the region where it overlaps with the second plate-like portion 3c2. Thereby, the wing portion 3 can gain thickness at the connecting portion with the steel pipe 10, and even if a moment is generated in the connecting portion and its vicinity when a load is applied to the steel pipe pile 100 and becomes large, it is possible to suppress the wing portion 3 from being damaged or bent. Note that the first plate-like portion 3c1 and the steel pipe edge portion 1e (the first steel pipe edge portion 1e1) are connected to each other by welding, but alternatively, alternative connecting means such as adhesives and bolts can be used alone or in combination with welding.

[0031] The thickness (mm) of the first plate-like portion 3c1 is, for example, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, and it may be within the range between any two of the values exemplified here.

[0032] <The second plate-like portion 3c2 of the first wing portion 3a> The second plate-like portion 3c2 is a flat plate having a fan shape (semicircular shape in the first embodiment) in plan view. The central angle (degrees) of the shape of the second plate-like portion 3c2 in plan view is 180 degrees. Note that the central angle is not limited to this, and specifically, for example, it is 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, and it may be within the range between any two of the values exemplified here.

[0033] The second plate-like portion 3c2 is connected to the first plate-like portion 3c1. That is, the second plate-like portion 3c2 is not directly connected to the steel pipe 10, but is fixed to the steel pipe 10 via the first plate-like portion 3c1. The second plate-like portion 3c2 is connected to both the outer edge portion 3c11 and the inner edge portion 3c12 of the first plate-like portion 3c1. Note that these connection portions are connected to each other by welding, but alternatively, alternative connection means such as adhesives or bolts may be used alone or in combination with welding. Note that the welded portions described here are omitted in each figure, but are formed, for example, in a tapered shape at the outer edge portion 3c11 and the inner edge portion 3c12.

[0034] The thickness (mm) of the second plate-like portion 3c2 is, for example, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, and it may be within the range between any two of the values exemplified here.

[0035] 1-1-3-2. The second wing portion 3b Since the second wing portion 3b has a symmetrical shape with respect to the first wing portion 3a, the description will focus on the different parts, and the description of the same content will be omitted.

[0036] Most of the second wing portion 3b is disposed above the first wing portion 3a. Similar to the first wing portion 3a, the second wing portion 3b has a first plate-shaped portion 3c1 and a second plate-shaped portion 3c2 that are overlapped. In the region where the first plate-shaped portion 3c1 overlaps with the second plate-shaped portion 3c2, it is connected to the steel pipe edge portion 1e (the second steel pipe edge portion 1e2) of the tip surface 1b of the steel pipe 10.

[0037] In the first embodiment, when the steel pipe pile 100 is viewed from the side such that the opening portion 20 comes to the front side, the second wing portion 3b has a portion that intersects (overlaps) with the first wing portion 3a. The intersecting portion is disposed outside the steel pipe 10 when the steel pipe pile 100 is viewed from the side such that the opening portion 20 comes to the front side.

[0038] <Outer protrusion width and inner protrusion width> Referring to FIG. 5B, the first outer protrusion width W1, the second outer protrusion width W2, the first inner protrusion width L1, and the second inner protrusion width L2 are defined. The first outer protrusion width W1 is the width by which the first plate-shaped portion 3c1 protrudes from the outer surface 1d of the steel pipe 10 in the radial direction of the wing portion 3. In FIG. 5B, the position of the outer surface 1d of the steel pipe 10 corresponds to the position P1d. The second outer protrusion width W2 is the width by which the second plate-shaped portion 3c2 protrudes from the outer surface 1d of the steel pipe 10 in the radial direction of the wing portion 3. The first inner protrusion width L1 is the width by which the first plate-shaped portion 3c1 protrudes from the inner surface 1c of the steel pipe 10 in the radial direction of the wing portion 3. In FIG. 5B, the position of the inner surface 1c of the steel pipe 10 corresponds to the position P1c. The second inner protrusion width L2 is the width by which the second plate-shaped portion 3c2 protrudes from the inner surface 1c of the steel pipe 10 in the radial direction of the wing portion 3.

[0039] Here, the first outer protrusion width W1 is preferably 30% or more and 70% or less of the second outer protrusion width W2, more preferably 35% or more and 65% or less, and still more preferably 40% or more and 60% or less.

[0040] Also, the first inner protrusion width L1 is 30% or more and 70% or less of the second inner protrusion width L2, more preferably 35% or more and 65% or less, and still more preferably 40% or more and 60% or less.

[0041] By having the relationship between the first outer protrusion width W1 and the second outer protrusion width W2 (hereinafter also referred to as the first relationship) and the relationship between the first inner protrusion width L1 and the second inner protrusion width L2 (hereinafter also referred to as the second relationship) as described above, it becomes possible to perform reinforcement according to the distribution of the moment applied to the wing portion 3, and it is possible to effectively reinforce the wing portion 3 while suppressing the material of the plate material (the material of the first plate-like portion 3c1). It should be noted that it is preferable that both the first and second relationships are as described above, but an effect can be expected even if only one of them is satisfied.

[0042] 1-2. Operational effects of the first embodiment 1-2-1. Regarding the configuration of stacking a plurality of plate-like portions As the excavation portion provided in the steel pipe, a configuration in which plate-like portions are arranged spirally like in the first embodiment or a spiral configuration has been proposed. In these configurations of the excavation portion, basically, the thickness of the plate is constant. Here, during the construction using the steel pipe pile or when a load acts on the steel pipe pile, a moment is generated in the excavation portion like a cantilever beam, so a large stress is generated at the portion where the excavation portion is connected to the steel pipe, while the stress generated in portions such as the outer peripheral side of the excavation portion is small. Therefore, ideally, it is considered that the plate thickness of the excavation portion may be thick at the portion connected to the steel pipe and thin at the outer peripheral side portion and the inner peripheral side portion. However, such an excavation portion has the following problems (1) to (3).

[0043] (1) First, it is not easy to obtain a single plate material (flat steel plate) in which the plate thickness of the portion connected to the steel pipe is thick and the plate thickness of the outer peripheral side portion or the like is thin. (2) Among narrow-width rolled flat steels, although there are some with different plate thicknesses at both ends, the size of the plate thickness is limited, and it is not easy to process them into an arc shape. (3) It is possible to process a single plate material by mechanical cutting or the like to change the plate thickness according to the part, but the cost increases significantly due to processing labor, yield, etc. Based on these (1) to (3), it is not easy to manufacture the above-described ideal cutting part using a single plate material.

[0044] Also, it is conceivable to use casting in the manufacturing method. However, even in this case, there are problems as described in the following (4). (4) When performing casting, the plate thickness can be changed in the outer peripheral radial direction. However, it is necessary to prepare molds for each pile diameter and blade diameter. When manufacturing many types of products, the number of molds increases, and when manufacturing large products, the molds become large, raising concerns about management problems and increased manufacturing costs. In addition, productivity decreases, such as the cooling after casting taking a long time. Thus, although casting can manufacture an excavation part having portions with different thicknesses, there are problems in terms of management, cost, and productivity.

[0045] 1-2-1-1. Suppression of damage, etc. In the first embodiment, in the region where the blade part 3 and the steel pipe edge part 1e are connected, since the first plate-like part 3c1 and the second plate-like part 3c2 overlap, the thickness of the blade part 3 in the region can be easily ensured. Here, although this region is a portion where stress is likely to increase, the thickness is ensured, suppressing the blade part 3 from being damaged or bent.

[0046] 1-2-1-2. Regarding manufacturing cost In the first embodiment, it is not necessary to perform processing or the like so that the thickness of a single plate material varies according to the part. Since the first plate-like part 3c1 and the second plate-like part 3c2 are overlapped to increase the thickness, it is possible to expect an effect of suppressing an increase in the manufacturing cost when manufacturing an excavation part having different thicknesses according to the part. Further, the first plate-like part 3c1 is a plate-like part for reinforcement at the connection part with the steel pipe 10 and does not need to have the same size as the second plate-like part 3c2. For this reason, it is not necessary to stack two plates having the same shape as the second plate-like part 3c2, and it is possible to suppress the manufacturing cost by suppressing the weight of the material of the excavation part (cost reduction by reducing the steel weight).

[0047] 1-2-1-3. Diversification of shape and rationalization of inventory management In the first embodiment, the wing part 3 is manufactured by overlapping plate-like parts. Here, by preparing plate-like parts with several types of plate thicknesses, it is possible to easily increase the types of wing parts 3 that can be manufactured by their combination. If an attempt is made to manufacture a wing part with only a single plate material, problems such as those described in (1) to (3) above will occur. However, in the case of the overlapping plate method as in the first embodiment, by procuring plate-like parts with different plate thicknesses, wing parts 3 of various shapes can be easily manufactured, and inventory management can also be significantly rationalized.

[0048] 1-2-2. Reduction of penetration resistance In the first embodiment, when the wing part 3 is viewed in plan, the first plate-like part 3c1 is arranged inside the edge of the second plate-like part 3c2. That is, the first plate-like part 3c1 is smaller in size than the second plate-like part 3c2. For this reason, although the thickness of the wing part 3 is thick at the connection part with the steel pipe 10, the thickness is suppressed in other parts (outer peripheral parts, etc.). As a result, when the steel pipe pile 100 is viewed from the front side (see FIG. 3A), the area of the wing part 3 is suppressed, and it is easier to penetrate into the ground. Therefore, it is possible to suppress the rotational torque when the steel pipe pile 100 is being penetrated and the force required when the steel pipe pile 100 is being pushed in or pulled out, and it is possible to reduce the penetration resistance of the steel pipe pile 100.

[0049] 1-3. Modification example of the first embodiment 1-3-1. Modification Example 1: Making the thicknesses of multiple plate-like parts different As shown in FIGS. 7A and 7B, in Modification Example 1, the thickness T2 of the second plate-like part 3c2 is made larger than the thickness T1 of the first plate-like part 3c1.

[0050] When manufacturing a wing part by stacking plate-like parts, usually, the outer peripheral part of the upper plate-like part is fixed by fillet welding. When sufficient fixing performance is obtained, the displacement between the first plate-like part 3c1 (upper plate-like part) and the second plate-like part 3c2 (lower plate-like part) does not occur. Therefore, as a structure of a built-up beam, the two plates will exhibit bending rigidity as a composite cross-section. On the other hand, when a vertical load acts on the two plate-like parts, a force that tries to displace each other due to the bending of the plate-like parts acts. The shear force that tries to cause such displacement changes depending on the bending rigidity of the plate-like parts. For example, even if the total thickness of the first plate-like part 3c1 and the second plate-like part 3c2 is the same, when the second plate-like part 3c2 is thick and the first plate-like part 3c1 is thin, the shear force generated in the first plate-like part 3c1 is small. When the thickness relationship is reversed, the shear force generated in the first plate-like part 3c1 becomes large.

[0051] Therefore, the shear force generated according to the thickness of the plate-like part is different. When the thickness of the first plate-like part 3c1 is thin, the fillet welding required to prevent displacement can be small, while when the thickness of the first plate-like part 3c1 is thick, the welding amount (fillet welding amount) required for the first plate-like part 3c1 becomes large. Therefore, when stacking plate-like parts, it is possible to reduce the processing cost by making the thickness of the first plate-like part 3c1 thinner than the thickness of the second plate-like part 3c2 and reducing the welding amount. As shown in FIG. 7B, it can be seen that the welded portion WE between the first plate-like part 3c1 and the second plate-like part 3c2 is suppressed due to the thinness of the first plate-like part 3c1.

[0052] 1-3-2. Modification Example 2: The number of plate-like parts of each wing part In the first embodiment, the case where the number of plate-like portions of the wing portion 3 is two has been described as an example, but the present invention is not limited thereto. As shown in FIGS. 8A and 8B, in the modified example 2, the wing portion 3 further includes a third plate-like portion 3c3 in addition to the first plate-like portion 3c1 and the second plate-like portion 3c2. The third plate-like portion 3c3 is welded to the second plate-like portion 3c2 and fixed to the second plate-like portion 3c2. Note that the number of plate-like portions may be four or more, and for example, it can be set according to the rigidity required for the wing portion 3 or the like.

[0053] 2. Second Embodiment 2-1. Configuration Explanation of the Second Embodiment In the second embodiment, the same reference numerals are given to the configurations common to the first embodiment, and the different parts will be mainly described, and the description of the same content will be omitted.

[0054] As shown in FIGS. 9A to 11B, the steel pipe pile 100 includes a steel pipe 10, an opening portion 20, an excavation portion 30, and a reinforcing member 40.

[0055] 2-1-1. Steel Pipe 10 In the second embodiment, since the steel pipe 10 is the same as that described in the explanation of the first embodiment (1-1-1. Steel Pipe 10), the description thereof will be omitted.

[0056] 2-1-2. Opening Portion 20 In the second embodiment, since the opening portion 20 is the same as that described in the explanation of the first embodiment (1-1-2. Opening Portion 20), the description thereof will be omitted.

[0057] 2-1-3. Excavation Portion 30 As shown in FIGS. 9A to 11B, in the second embodiment, each wing portion of the excavation portion 30 does not have a form in which plate-like portions are stacked. That is, the first wing portion 3a in the second embodiment is the second plate-like portion 3c2 of the first wing portion 3a described in the first embodiment. Similarly, the second wing portion 3b in the second embodiment is the second plate-like portion 3c2 of the second wing portion 3b described in the first embodiment.

[0058] The excavation part 30 has the blade parts 3. In the second embodiment, the blade parts 3 are composed of a plurality (two in the second embodiment) of independent blade parts (the first blade part 3a and the second blade part 3b). Note that, although the number of blade parts is described as two as in the first embodiment, it is not limited thereto, and the steel pipe pile 100 may have a form having three or more independent blade parts. The plurality of independent blade parts are flat plate members adjacent to each other. Each blade part is provided so as to be inclined when the steel pipe pile 100 is viewed from the side. However, as shown in Fig. 11A, the inclination angles of the two blade parts are different.

[0059] 2-1-3-1. The first blade part 3a The first blade part 3a is a flat plate having a fan shape (semicircular shape in the second embodiment) in plan view. The first blade part 3a is connected to the steel pipe edge part 1e (the first steel pipe edge part 1e1) of the tip surface 1b of the steel pipe 10.

[0060] The first blade part 3a has a central angle (degrees) of 180 degrees in plan view. Note that the central angle is not limited thereto, and specifically, for example, it is 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, and it may be within the range between any two of the numerical values exemplified here.

[0061] The thickness (mm) of the first blade part 3a is, for example, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, and it may be within the range between any two of the numerical values exemplified here.

[0062] 2-1-3-2. The second blade part 3b The shape of the second blade part 3b is symmetric to that of the first blade part 3a, and since the other parts are the same, the different parts will be mainly described, and the description of the same content will be omitted.

[0063] Most of the second blade part 3b is disposed above the first blade part 3a. The second blade part 3b is connected to the steel pipe edge part 1e (the second steel pipe edge part 1e2) of the tip surface 1b of the steel pipe 10.

[0064] In the second embodiment, when the steel pipe pile 100 is viewed from the side such that the opening 20 is on the front side, the second wing portion 3b has a portion that intersects (overlaps) the first wing portion 3a. The intersecting portion is disposed outside the steel pipe 10 when the steel pipe pile 100 is viewed from the side such that the opening 20 is on the front side.

[0065] <Inclination angle> As shown in FIG. 11A, the first virtual plane P1 is a plane that is orthogonal to the central axis C of the steel pipe 10 and passes through the central height position between the first terminal 1e12 of the first steel pipe edge portion 1e1 and the second tip 1e21 of the second steel pipe edge portion 1e2. Here, let the angle formed by the first wing portion 3a and the first virtual plane P1 be the first inclination angle θ1, and the angle formed by the second wing portion 3b and the first virtual plane P1 be the second inclination angle θ2. In the second embodiment, as shown in FIG. 11A, the second inclination angle θ2 is larger than the first inclination angle θ1.

[0066] Here, the first inclination angle (degrees) is specifically, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, and may be within the range between any two of the values exemplified here. For example, the first inclination angle is 2 degrees or more and 20 degrees or less.

[0067] Also, the second inclination angle (degrees) is specifically, for example, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, and may be within the range between any two of the values exemplified here. For example, the second inclination angle is 3 degrees or more and 30 degrees or less.

[0068] <Opening area> As shown in Fig. 11A, the opening area of the opening 20 between the first wing portion 3a and the first virtual plane P1 is defined as the first opening area Ar1, and the opening area of the opening 20 between the second wing portion 3b and the first virtual plane P1 is defined as the second opening area Ar2. In the second embodiment, the second opening area Ar2 is larger than the first opening area Ar1. More specifically, as shown in Fig. 11A, the first opening area Ar1 is the area of the trapezoidal region surrounded by the upper surface of the first wing portion 3a, the vertical edge portions 1f on both sides, and the first virtual plane P1 when the steel pipe pile 100 is viewed from the side (front side) on the opening 20 side. Also, as shown in Fig. 11A, the second opening area Ar2 is the area of the trapezoidal region surrounded by the lower surface of the second wing portion 3b, the vertical edge portions 1f on both sides, and the first virtual plane P1 when the steel pipe pile 100 is viewed from the side (front side) on the opening 20 side.

[0069] <Support area> As shown in Fig. 14, when the excavation portion 30 is viewed from the direction of the central axis C of the steel pipe 10, a circular region Rg is defined with the position of the central axis C as the center O and the distance between the center O and the farthest position p as the radius. The farthest position p is the position of the portion of the excavation portion 30 that is farthest from the central axis C of the steel pipe 10. When the excavation portion 30 is viewed from the direction of the central axis C of the steel pipe 10, the range where the excavation portion 30 is provided is preferably 70% or more of the total area of the circular region Rg. Note that this value is not limited to 70%. Specifically, for example, it may be 70, 75, 80, 85, 90, 95, 100%, or within the range between any two of the values exemplified here. By setting the value in this way, a wider area of the lower surface of the excavation portion 30 can be ensured, and it becomes easier to ensure the supporting force of the steel pipe pile 100.

[0070] <Distribution of the wing portion 3> As shown in Fig. 14, when the space is divided into a first divided space Sp1 and a second divided space Sp2 by a second virtual plane P2 passing through the central axis C of the steel pipe 10, the first wing portion 3a is disposed in the first divided space Sp1, and at least a part of the second wing portion 3b is disposed in the second divided space Sp2. The second virtual plane P2 bisects the space into the first divided space Sp1 and the second divided space Sp2. In the second embodiment, the whole of the first wing portion 3a is disposed in the first divided space Sp1, and the whole of the second wing portion 3b is disposed in the second divided space Sp2. Thus, in the second embodiment, the arrangement of the wing portions 3 is not unevenly distributed in one divided space, but is distributed in both spaces (the first divided space Sp1 and the second divided space Sp2). In particular, in the second embodiment, the wing portions 3 are arranged so as to be evenly distributed in the first divided space Sp1 and the second divided space Sp2. For example, the whole of the first wing portion 3a may be disposed in the first divided space Sp1, and the second wing portion 3b may be disposed across the first divided space Sp1 and the second divided space Sp2. Also, the first wing portion 3a may be disposed across the first divided space Sp1 and the second divided space Sp2, and the whole of the second wing portion 3b may be disposed in the second divided space Sp2. Note that the distribution of the wing portions 3 described here is the same also in the first embodiment.

[0071] 2-1-4. Reinforcing member 40 As shown in Figs. 13A and 13B, the reinforcing member 40 is provided in the opening portion 20 (the tip portion 1a of the steel pipe 10) along the inner surface 1c of the steel pipe 10. The portion of the steel pipe 10 where the opening portion 20 is formed is a portion that collides with the object to be excavated, and strength is required. For this reason, the steel pipe 10 is internally provided with the reinforcing member 40.

[0072] As shown in Fig. 11A, the reinforcing member 40 is attached to the longer vertical edge portion 1f of the pair of vertical edge portions 1f. Specifically, the reinforcing member 40 is provided along the inner surface 1c of the steel pipe 10 at a position corresponding to the vertical edge portion 1f. When the height width of the reinforcing member 40 is w1 and the height width of this vertical edge portion 1f is w2, the value of w1 / w2 is specifically, for example, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, and it may also be within the range between any two of the numerical values exemplified here.

[0073] The reinforcing member 40 is formed to taper in a cross-section parallel to the first virtual plane P1. In other words, the reinforcing member 40 has a wedge shape in a cross-section parallel to the first virtual plane P1. The tapered tip portion of the reinforcing member 40 is provided so as to face the opening of the opening portion 20. Note that the tapered tip portion of the reinforcing member 40 may be provided inside the steel pipe 10 and may not protrude from the opening of the opening portion 20, or may be provided outside the steel pipe 10 and may protrude from the opening of the opening portion 20.

[0074] As shown in Fig. 13B, the reinforcing member 40 is welded to the inner surface 1c of the steel pipe 10 by welding. In Fig. 13B, a welded portion 41 is formed at the tip portion and the rear side portion of the reinforcing member 40. Note that the fixing method of the reinforcing member 40 is not limited to welding, and for example, alternative connecting means such as adhesives and bolts can be used alone or in combination with welding.

[0075] 2-2. Effects of the Second Embodiment 2-2-1. Regarding the Opening Area In the second embodiment, even if the inclination angle of the first blade portion 3a is suppressed from the viewpoint of reducing resistance in excavation, for example, the inclination angle of the second blade portion 3b is ensured to be larger than the inclination angle of the first blade portion 3a. Therefore, the second opening area Ar2 is ensured to be larger than the first opening area Ar1. For this reason, it is suppressed that the object to be excavated is difficult to be taken into the steel pipe 10, and it is suppressed that the penetrability of the steel pipe pile 100 is impaired.

[0076] 2-2-2. Regarding the inclination angle When the steel pipe pile is rotationally penetrated, the tip of the blade part excavates the ground, and the excavated material is moved upward along the blade part. As a result, the blade part receives a downward force and the steel pipe pile penetrates. At the lower end of the blade part that excavates the new ground, a large reaction force is received during excavation. However, once the excavated earth and sand are plasticized, the downward reaction force decreases while moving upward along the blade part. For this reason, if the angle of the blade part is constant in the spiral direction (substantially spiral direction), there is a concern that the upper part of the blade part cannot appropriately receive the reaction force from the excavated material. In the second embodiment, the second inclination angle θ2 of the second blade part 3b is larger than the first inclination angle θ1 of the first blade part 3a. First, the resistance during excavation can be suppressed by the first blade part 3a with a relatively small inclination angle. Since the first blade part 3a is the part that first contacts the ground, it goes without saying that a downward reaction force is ensured. Second, when the excavated material moves on the upper surface of the second blade part 3b, the second blade part 3b has a relatively large inclination angle and can receive a large downward reaction force from the excavated material. That is, the steel pipe pile 100 can also appropriately receive the downward reaction force at the second blade part 3b, and the penetrability is improved.

[0077] 2-2-3. Regarding ensuring the supporting force When the excavation part (blade part) is viewed from the central axis direction of the steel pipe, if openings, notches, etc. are formed in the excavation part, the area of the lower surface of the steel pipe pile (excavation part) is reduced accordingly. When an upward and downward force acts on the steel pipe pile, there is a concern that the reaction force from the ground cannot be obtained and the supporting force decreases. In the second embodiment, when the excavation part 30 is viewed from the direction of the central axis C of the steel pipe 10, the range where the excavation part 30 (blade part 3) is provided is 70% or more of the total area of the circular region Rg (almost 100% in the second embodiment). Thereby, the area of the lower surface of the excavation part 30 can be ensured more widely, and it becomes easier to ensure the supporting force of the steel pipe pile 100.

[0078] 2-2-4. Reinforcement of the opening part A means of attaching a flat reinforcing member instead of the reinforcing member 40 to the opening part 20 to reinforce the opening part 20 can be considered. However, in this means, since the earth and sand hit the reinforcing plate during the intake of earth and sand, the resistance increases. Furthermore, with a flat reinforcing member, it is difficult to secure a region where the excavated material does not contact the region 42 behind the reinforcing member, and there is a concern that the opening part 20 may be easily blocked. On the other hand, in the second embodiment, since the reinforcing member 40 formed to taper toward the opening part 20 is provided, the resistance during the intake of the excavated material can be reduced. Also, in the second embodiment, since the width of the portion on the back side of the reinforcing member 40 is wider than the portion on the tip side of the reinforcing member 40, it is easy to secure a region where the excavated material does not contact the region 42 behind the reinforcing member 40, and a large region where the excavated material does not contact the inner surface 1c of the steel pipe 10 can be obtained, the blocking of the opening part 20 can be suppressed, and the resistance during penetration can be suppressed.

[0079] 2-3. Modification of the second embodiment 2-3-1. Other shapes of the reinforcing member 40 In the second embodiment, the cross-sectional shape of the reinforcing member 40 has been described as triangular, but it is not limited to this. As shown in Fig. 15A, the cross-sectional shape of the reinforcing member 40 may be circular. In this case, the welded part 41 may be formed to taper toward the opening part 20. Thereby, it is possible to obtain the same effects as the reinforcing member 40 described in the second embodiment. Also, as shown in Fig. 15B, the cross-sectional shape of the reinforcing member 40 may be trapezoidal. Even in this case, by forming the welded part 41 to taper toward the opening part 20, it is possible to obtain the same effects as the reinforcing member 40 described in the second embodiment.

[0080] 2-3-2. Forms with different opening areas In the second embodiment, the inclination angles of the first wing portion 3a and the second wing portion 3b were different, so that the first opening area Ar1 and the second opening area Ar2 were different, but the present invention is not limited to this. That is, in making the opening areas different, it is not essential that the inclination angle of the second wing portion 3b be larger than the inclination angle of the first wing portion 3a. For example, even if the inclination angles of the first wing portion 3a and the second wing portion 3b are the same, the first opening area Ar1 and the second opening area Ar2 can be made different depending on the shape of the vertical edge portion 1f.

[0081] 2-3-3. Regarding the shape of the edge of the wing portion 3 In this modification example, the edge of the first wing portion 3a has a tapered shape, and it is a form in which the penetration into the ground is good. Specifically, as shown in FIGS. 16A and 16B, the edge t1 of the first wing portion 3a may have a tapered shape. The edge t1 extends linearly and is disposed at the formation position of the opening portion 20. Since the edge t1 has a tapered shape and is angled like a cutting edge, the resistance during excavation can be reduced, it is easy to penetrate into the ground, and the excavated material can be easily taken into the pipe. Similarly, the edge t2 of the first wing portion 3a may also have a tapered shape. The edge t2 is provided at the peripheral edge of the first wing portion 3a and extends in an arc shape (circular arc shape in this modification example). Since the edge t2 has a tapered shape and is angled like a cutting edge, the penetrability into the ground can be improved, the penetration resistance can be reduced, and the penetrability can be improved. Note that the second wing portion 3b also has the same configuration as the first wing portion 3a, and its edge may have a tapered shape.

[0082] 3. Other embodiments The first embodiment, modification examples 1 and 2 of the first embodiment, the second embodiment, and modification examples of the second embodiment can be appropriately combined. For example, as in the first embodiment, after the plate-like portions of the first wing portion 3a and the second wing portion 3b are overlapped, as in the second embodiment, the second opening area Ar2 may be larger than the first opening area Ar1, or the second inclination angle θ2 may be larger than the first inclination angle θ1. Also, on the premise of the form in which the plate-like portions of the first wing portion 3a and the second wing portion 3b are overlapped as in the first embodiment, the reinforcing member 40 described in the second embodiment or its modification may be provided in the opening portion 20.

Explanation of Reference Numerals

[0083] 100: Steel pipe pile 10: Steel pipe 1a: Tip 1b: Tip surface 1c: Inner surface 1d: Outer surface 1e: Steel pipe edge 1e1: First steel pipe edge 1e11: First tip 1e12: First terminal 1e2: Second steel pipe edge 1e21: Second tip 1e22: Second terminal 1f: Vertical edge 20: Opening portion 30: Excavation portion 3: Wing portion 3a: First wing portion 3b: Second wing portion 3c1: First plate-like portion 3c2: Second plate-like portion 3c11: Outer edge 3c12: Inner edge 40: Reinforcing member 41: Welded portion 42: Region C: Central axis О: Center p: Furthest position P1: First virtual plane P2: Second virtual plane tp: Tip t1: Edge t2: Edge

Claims

1. A steel pipe pile having an excavation part at the tip of the steel pipe, wherein the excavation part is provided with an opening part for taking in the object to be excavated into the steel pipe, the excavation part has flat plate-shaped first and second wing parts adjacent to each other, the first wing part is connected to a first steel pipe edge part among the steel pipe edge parts of the tip surface of the steel pipe, the second wing part is connected to a second steel pipe edge part which is a part connected to the steel pipe edge part, in the central axis direction of the steel pipe, the first steel pipe edge part extends away from the tip of the steel pipe as it goes from the first tip of the first steel pipe edge part to the first terminal of the first steel pipe edge part, in the central axis direction of the steel pipe, the second steel pipe edge part extends away from the tip of the steel pipe as it goes from the second tip of the second steel pipe edge part to the second terminal of the second steel pipe edge part, in the central axis direction of the steel pipe, the distance between the second tip and the tip of the steel pipe is larger than the distance between the first tip and the tip of the steel pipe, when the opening area of the opening part between the first wing part and a first virtual plane is defined as a first opening area, when the opening area of the opening part between the second wing part and the first virtual plane is defined as a second opening area, the first virtual plane is orthogonal to the central axis of the steel pipe and passes through the central height position between the first terminal and the second tip, the second opening area is larger than the first opening area, a steel pipe pile.

2. The steel pipe pile according to Claim 1, wherein when the angle formed by the first wing part and the first virtual plane is defined as a first inclination angle, and the angle formed by the second wing part and the first virtual plane is defined as a second inclination angle, the second inclination angle is larger than the first inclination angle, a steel pipe pile.

3. The steel pipe pile according to Claim 2, wherein the first inclination angle is 2 degrees or more and 20 degrees or less, and the second inclination angle is 3 degrees or more and 30 degrees or less, a steel pipe pile.

4. The steel pipe pile according to any one of Claims 1 to 3, further comprising a reinforcing member, wherein the reinforcing member is provided in the opening part along the inner surface of the steel pipe, and the reinforcing member is formed to taper in a cross section parallel to the first virtual plane, a steel pipe pile.

5. The steel pipe pile according to any one of Claims 1 to 3, when looking at the excavation part in the central axis direction of the steel pipe, when a circular region is defined with the position of the central axis as the center and the distance between the center and the farthest position as the radius, The farthest position is the position of the portion of the excavation part that is farthest from the central axis of the steel pipe. When the excavation part is viewed from the direction of the central axis of the steel pipe, the range where the excavation part is provided is 70% or more of the total area of the circular region. Steel pipe pile.

6. A steel pipe pile according to any one of Claims 1 to 3, When the space is divided into a first and a second divided space by a second virtual plane passing through the central axis of the steel pipe, The first wing part is arranged in the first divided space, A steel pipe pile in which at least a part of the second wing part is arranged in the second divided space.

7. A steel pipe pile according to any one of Claims 1 to 3, The excavation part includes three or more wing parts, Among the plurality of wing parts, at least two adjacent wing parts are the first wing part and the second wing part. Steel pipe pile.

8. A steel pipe pile according to any one of Claims 1 to 3, A steel pipe pile in which the edge of the first wing part has a tapered shape.

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