Manufacturing and design methods for winged piles

Abstract

To provide a manufacturing method of a winged pile with high performance with less joint failure and stress concentration when joining a pseudo-helical blade or a flat plate blade to a pipe end, and a design method.SOLUTION: A manufacturing method of a winged pile 1 is a manufacturing method of a winged pile 1 with a flat plate blade 5 or a pseudo-helical blade having a diameter larger than the diameter of a tube, which is attached in an axially inclined state with respect to the central axis of the tube at the tip surface of the cylindrical tube. The method includes: an inclined end face formation step of forming a radially inclined end face 7 which is axially inclined as well as radially inclined at the tip surface of the tube in contact with the flat plate blade 5 or the pseudo-helical blade; and a wing joining step of joining with the upper surface of the flat plate blade 5 or the pseudo-helical blade in contact with the inclined end surface 7. The inclined end face formation step forms the inclined end face so that the upper surface of flat plate blade 5 or the pseudo-helical blade fully comes into contact with the inclined end surface in the plate thickness direction due to a change of the radial inclination angle of the inclined end face 7 depending on the circumferential position.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a manufacturing method and a design method for a winged pile in which a flat plate wing or a pseudo-spiral wing is attached to the tip surface of a cylindrical pipe at an angle with respect to the central axis of the pipe. In this specification, a pseudo-helical blade refers to a blade formed by cutting a radial line at one point on a circular or doughnut-shaped plate and deforming the circular or doughnut-shaped plate so that the cut point separates in the vertical direction to form a pseudo-helical shape. [Background technology]

[0002] A commonly used construction method for steel pipe piles is to attach tip wings larger than the diameter of the steel pipe to the tip face or near the tip face of the steel pipe, and rotate the pile into the ground. As low-cost tip wings for such winged steel pipe piles, there are pseudo-helical wings (hereinafter referred to as "pseudo-helical wings") made by simply bending a flat plate (see Patent Document 1), and flat plate wings made by combining multiple flat plates and attaching them at a certain inclination to the steel pipe axis (see Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-220738 A [Patent Document 2] Japanese Patent Application Publication No. 9-324419 Summary of the Invention [Problem to be solved by the invention]

[0004] In the case of a helical impeller, whose blade shape is strictly helical, when viewed in the radial direction from the center of the steel pipe, the helical impeller is perpendicular to the pipe axis over its entire circumference. However, in the case of pseudo-spiral blades and flat blades, the blades are inclined when viewed in the radial direction from the center of the steel pipe. More specifically, when viewed from the center of the steel pipe, the angle between the blade and the outer surface of the steel pipe is an obtuse angle when viewed from the top of the steel pipe in a direction in which the outer periphery of the blade is closer to the pile tip than the steel pipe attachment part, and the angle is an acute angle when viewed from the top of the steel pipe in a direction in which the outer periphery of the blade is closer to the pile head than the steel pipe attachment part.

[0005] This point will be explained with reference to FIG. 6, taking as an example a winged steel pipe pile 11 in which two semicircular flat plate wings 5 ​​are attached to the end of a steel pipe 3. FIG. 6(a) is a side view of the tip of the winged steel pipe pile 11, FIG. 6(b) is a view taken along the line AA of FIG. 6(a), and FIG. 6(c) is a view taken along the line BB of FIG. 6(b).

[0006] As shown in Figure 6(c), when viewed from the center of the steel pipe 3, the angle α between the outer surface of the steel pipe and the flat plate wing 5 in the direction where the outer periphery of the flat plate wing 5 is located toward the pile tip side from the steel pipe attachment part is an obtuse angle, and the angle β between the outer surface of the steel pipe and the flat plate wing 5 in the direction where the outer periphery of the flat plate wing 5 is located toward the pile head side from the steel pipe attachment side is an acute angle.

[0007] The steel pipe 3 is usually cut by first marking the outer periphery of the steel pipe with the inclination of the flat blade 5, and then cutting perpendicular to the steel pipe surface using gas or the like. Therefore, the cut surface becomes a flat surface 13 perpendicular to the outer surface of the steel pipe 3, and when the flat blade 5 is aligned with such a flat surface 13, in most positions only either the outer surface or the inner surface of the steel pipe comes into contact with the flat blade 5, and a gap S is created on the non-contact side (see the enlarged view in Figure 6(c)). Therefore, for example, when joining flat plate blades 5 by welding, if the outer surfaces are in contact, normal fillet welding is possible, but if there is a gap S on the outer surface side, there is a possibility that the weld bead will partially penetrate into the gap S, which not only makes welding defects more likely to occur but also requires wasted welding material. In addition, when a compressive load is applied to a pile, the load is transmitted only at the welded parts and the parts in contact, which may result in extremely high local stress (stress concentration). Such problems occur not only when the flat plate wing 5 is joined by welding, but also when it is joined with a structural adhesive.

[0008] The present invention has been made to solve such problems, and aims to provide a manufacturing and design method for a high-performance winged pile that is less likely to cause poor joining or stress concentration when joining a pseudo-spiral wing or flat plate wing to a pipe end. [Means for solving the problem]

[0009] (1) The method for manufacturing a winged pile according to the present invention is a method for manufacturing a winged pile in which a flat plate wing or a pseudo-spiral wing having a diameter larger than the diameter of a cylindrical pipe is attached to the tip surface of the pipe in a state inclined in the axial direction relative to the central axis of the pipe, a step of forming an inclined end surface on a tip end surface of the tube that is in contact with an upper surface of the flat plate blade or the pseudo-spiral blade, the tip end surface being inclined in the axial direction and also inclined in the radial direction; a blade joining step of abutting and joining an upper surface of the flat plate blade or the pseudo-spiral blade to the inclined end surface, The inclined end surface forming step forms the inclined end surface such that the radial inclination angle changes depending on the circumferential position, so that the upper surface of the flat plate blade or pseudo-spiral blade abuts against the entire surface of the inclined end surface in the plate thickness direction.

[0010] (2) In addition, in the above-described (1), the inclined end face forming step includes setting cutting lines around the entire circumference of the inner and outer surfaces of the pipe, and cutting the inner and outer surfaces of the pipe so as to connect the cutting lines in the thickness direction of the pipe.

[0011] (3) A method for designing a winged pile according to the present invention is a method for designing a winged pile in which a flat plate wing or a pseudo-spiral wing having a diameter larger than the diameter of a cylindrical pipe is attached to the tip surface of the cylindrical pipe in a state inclined in the axial direction relative to the central axis of the pipe, A radially inclined end surface is provided on a tip end surface of the tube that is in contact with an upper surface of the flat plate blade or the pseudo-spiral blade, the end surface being inclined in the axial direction and also inclined in the radial direction; The upper surface of the flat plate blade or the pseudo-spiral blade is abutted against and joined to the inclined end surface, The inclined end face is set so that the radial inclination angle of the inclined end face changes depending on the circumferential position, and so that the upper surface of the flat plate blade or pseudo-spiral blade abuts against the entire surface of the inclined end face in the plate thickness direction.

[0012] (4) Furthermore, in the above-mentioned (3), the inclined end face is set by setting an inner pipe surface line around the entire circumference on the inner pipe surface side and an outer pipe surface line around the entire circumference on the outer pipe surface side, and setting the inner pipe surface line and the outer pipe surface line so as to be connected in the thickness direction of the pipe. Effect of the Invention

[0013] According to the design method of a winged pile of the present invention, it is possible to manufacture a high-performance pile in which poor joining or stress concentration is unlikely to occur when joining the pseudo-spiral wing or flat plate wing to the pipe end. [Brief description of the drawings]

[0014] [Figure 1] 1 is an explanatory diagram of a winged pile manufactured by a winged pile manufacturing method according to this embodiment. FIG. [Diagram 2] 4 is an explanatory diagram illustrating steps of a manufacturing method for a winged pile according to the present embodiment. FIG. [Diagram 3] FIG. 1 is an explanatory diagram illustrating a gap that occurs when the tip of a steel pipe is cut perpendicular to the surface of the steel pipe and a flat plate blade is attached. [Figure 4] 1 is a graph showing the relationship between the height of the outer surface and inner surface of the steel pipe that are in contact with the flat plate blades at the tip surface of the steel pipe and the circumferential angle. [Diagram 5] 1 is a graph showing the relationship between the gap and the circumferential angle when a flat blade is attached to the tip face of a steel pipe cut perpendicular to the steel pipe surface. [Figure 6] FIG. 1 is an explanatory diagram illustrating the problems that arise when a flat blade is attached to a tip surface of a steel pipe cut perpendicular to the steel pipe surface. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] A manufacturing method for a winged pile according to this embodiment will be described with reference to Figs. 1 to 5, taking as an example the case of attaching a flat plate wing 5 to the tip of a steel pipe. In each figure, the same parts as those in Fig. 6 and corresponding parts are given the same reference numerals, and their description will be omitted. Here, in Fig. 1(b), C is marked at a position rotated 90° counterclockwise from B on the right side, and C' is marked at a position rotated 90° counterclockwise from B on the left side. Therefore, the dashed dotted line indicating the vertical center line of the pipe coincides with the line connecting C and C'.

[0016] The manufacturing method of a winged pile in this embodiment is a method of manufacturing a winged pile 1 by attaching a flat plate wing 5 having a diameter larger than the diameter of a cylindrical steel pipe 3 to the tip of the steel pipe 3 in an axially inclined state relative to the central axis of the steel pipe 3, as shown in Figure 1. Then, an inclined end surface forming step (see FIG. 2(a)) is performed to form an inclined end surface 7 that is inclined in both the axial direction and the radial direction on the tip surface of the steel pipe 3 that contacts the upper surface of the flat plate blade 5. The inclined end surface 7 is provided with a blade joining step (see FIGS. 2(b) and (c)) for joining the upper surface of the flat plate blade 5 by abutting it against the inclined end surface 7. Each step will now be described in detail.

[0017] <Inclined end face formation step> As described above, the inclined end surface forming step is a step of forming the inclined end surface 7 that is inclined in both the axial direction and the radial direction on the tip surface of the steel pipe 3 that abuts against the upper surface of the flat plate blade 5. The inclined end surface forming step forms the inclined end surface 7 so that the radial inclination angle changes depending on the circumferential position, so that the upper surface of the flat plate blade 5 abuts against the entire surface of the inclined end surface 7 in the plate thickness direction.

[0018] Here, a method of forming the inclined end surface 7 for abutting the upper surface of the flat plate blade 5 with the entire surface of the inclined end surface 7 in the plate thickness direction will be described. The pitch of the winged pile 1 shown in Figure 1 determines how far the pile penetrates with one rotation, and if the ground is soft, the winged pile 1 penetrates at a rate close to the pitch. Normally, the pitch is 25% to 50% of the pile diameter. Also, the thickness of the steel pipe 3 to which the flat plate wings 5 ​​are attached is generally about 1.5% to 2.0% of the pile diameter.

[0019] As mentioned above, when the tip of the steel pipe 3 to which the flat plate wing 5 is to be attached is cut perpendicular to the surface of the steel pipe 3 and the flat plate wing 5 is aligned with the cut surface (flat surface 13), a gap S will be created between the cut surface and the flat plate wing 5 in most positions (for example, in the case of Figure 1(b) , all positions except for the dotted line connecting C and C'). Figure 3 shows the relationship between pile diameter, pitch, steel pipe thickness, and gap S when two flat plate wings 5 ​​as shown in Figure 1 are attached. Figure 3 shows the gap S (maximum gap) at the part where the flat plate wings 5 ​​abut on the inside in the thickness direction of the tip face of the steel pipe. The gap amounts calculated based on FIG. 3 are shown in Table 1.

[0020] [Table 1]

[0021] As shown in Table 1, the larger the pile diameter, the larger the gap S, and when the pile diameter is 400 mm or more, the gap S is 1 mm or more. As described above, when such a gap S occurs between the flat plate 5 and the tip face of the steel pipe, problems such as the occurrence of welding defects, waste of welding material, and stress concentration occur.

[0022] The reason why such a gap S occurs is that the height of the steel pipe tip surface that contacts the flat plate blade 5 differs between the outer surface and the inner surface of the steel pipe, and this height changes depending on the circumferential angle. Figure 4 shows how the height of the outer and inner surfaces of the steel pipe in contact with the flat plate wing 5 changes depending on the angle, taking the flat plate wing 5 as an example, when the outer diameter D = 400 mm, the plate thickness t = 8 mm, and the inclination angle θ of the flat plate wing 5 = 7.125016° (when two flat plate wings form a pseudo-spiral, the pitch / pile diameter corresponds to 25%). In Fig. 4, the horizontal axis indicates the circumferential angle φ (°), which is a linear expansion of the circumferential position of the steel pipe 3. The lowest position of the flat plate blade 5 inclined in the axial direction is taken as 0 (°). The vertical axis indicates the height of the steel pipe tip face, and the position where the height of the steel pipe outer surface and the steel pipe inner surface are the same (the 90° position on the horizontal axis, i.e., the position on the dashed line connecting C and C' in Fig. 1(b)) is taken as 0 (mm).

[0023] As shown in FIG. 4, the height of the outer surface of the steel pipe (solid line) and the height of the inner surface of the steel pipe (dashed line) are not the same, but each changes depending on the circumferential angle. Therefore, when the tip of the steel pipe 3 is cut at a right angle to the surface of the steel pipe, the tip surface of the steel pipe will be at the same height on the outer surface and the inner surface of the steel pipe, resulting in a gap S corresponding to the difference in height between the outer surface and the inner surface of the steel pipe as shown in Figure 4. This gap S changes in the circumferential direction of the steel pipe 3, as shown in Figure 5.

[0024] In order to prevent such a gap S from occurring, the tip surface of the steel pipe should not be cut perpendicularly to the outer surface of the steel pipe, but should be cut to connect the solid line and the broken line in Fig. 4 in the radial direction to form an inclined end surface 7. By forming such an inclined end surface 7 at the location where the gap S occurs, the flat plate blade 5 abuts against the entire surface in the thickness direction of the inclined end surface 7 at any location in the circumferential direction (particularly preferably, the entire surface in the thickness direction from the outer surface side to the inner surface side of the steel pipe).

[0025] As a method for forming the inclined end surface 7 on the tip end surface of the steel pipe, in order to perform this mechanically, a cutting machine with a blade larger than the diameter of the steel pipe 3 is used, and the steel pipe 3 is cut by inclining the blade so as to satisfy the height relationship in Fig. 4. Note that a laser cutting machine can also be used instead of a blade.

[0026] In order to perform gas cutting, it is possible to mechanically adjust the torch angle, but if it is done manually, it is sufficient to draw a line corresponding to the solid line in Figure 4 on the outer surface of the tip of the steel pipe, draw a line corresponding to the dashed line in Figure 4 on the inner surface of the tip of the steel pipe, and connect these lines in the thickness direction of the steel pipe 3 before cutting. Alternatively, the two lines shown in Figure 4 may be scored on the inner and outer surfaces of the steel pipe 3, the longer side of the steel pipe 3 may be cut vertically as usual, and the remaining part may then be cut off. By the above-described method, the inclined end surface 7 is formed as shown in FIG. 2(a).

[0027] <Wing joining step> The blade joining step is a step in which the upper surface of the flat plate blade 5 is brought into contact with the inclined end surface 7 (see FIG. 2(b)), and joined by, for example, welding (see FIG. 2(c)). Since the steel pipe 3 has an inclined end surface 7 at its tip, the inclined end surface 7 and the flat plate 5 can be joined together without any gap or with less gap, as shown in Fig. 2(c). In other words, the contact surfaces of the inclined end surface 7 and the flat plate 5 can be welded in closer contact, reducing the possibility of welding defects, and the load is transmitted over the entire contact surface and the welded part, so no stress concentration occurs.

[0028] As described above, in this embodiment, when the flat plate wing 5 is joined to the pipe end, the inclined end face 7 and the flat plate wing 5 can be abutted with no gap or with less gap, making it possible to obtain a high-performance steel pipe pile with smooth stress transmission and less prone to poor joining or stress concentration. Furthermore, when forming the inclined end surface 7 at the tip of the steel pipe 3, lines corresponding to the solid and dashed lines in Figure 4 are drawn on the outer peripheral surface of the tip of the steel pipe, and these lines are cut so as to connect in the thickness direction of the steel pipe 3, so that the inclined end surface 7 can be formed accurately and simply.

[0029] In the above embodiment, the flat plate wing 5 is used as an example of the wing, but the wing may be a pseudo-spiral wing that is not a strictly spiral wing and may be manufactured in the same manner. Also, in the above embodiment, the semicircular flat plate wing 5 with the wing extending around the central axis is used as an example of the wing, but the donut-shaped (including semi-donut-shaped) flat plate wing that is open around the central axis may be manufactured in the same manner. Also, in the above explanation, the blade and the tip end face of the steel pipe are welded together, but they may be bonded together with a structural adhesive. Furthermore, in the above example, the steel pipe 3 is given as an example of the pipe that constitutes the pile, but the material of the pipe is not limited to steel, and it may be other metals or non-metallic materials, such as concrete.

[0030] Although the above description has been directed to an invention as a manufacturing method for the winged pile 1, the invention described in this specification can also be configured as a design method for a winged pile. When configured as a design method for winged piles, it can be expressed as follows:

[0031] A method for designing a winged pile in which a flat plate or pseudo-spiral wing having a diameter larger than the diameter of a cylindrical pipe is attached to the tip surface of the pipe in an axially inclined state relative to the central axis of the pipe, A radially inclined end surface is provided on a tip end surface of the tube that is in contact with an upper surface of the flat plate blade or the pseudo-spiral blade, the end surface being inclined in the axial direction and also inclined in the radial direction; The upper surface of the flat plate blade or the pseudo-spiral blade is abutted against and joined to the inclined end surface, This is a design method for a winged pile in which the inclined end face is set so that the radial inclination angle of the inclined end face changes depending on the circumferential position, and the upper surface of the flat wing or pseudo-spiral wing abuts the entire surface of the inclined end face in the plate thickness direction.

[0032] In addition, the inclined end face 7 can be set by setting an inner pipe surface line along the entire circumference on the inner pipe side and an outer pipe surface line along the entire circumference on the outer pipe side, and connecting the inner pipe surface line and the outer pipe surface line in the thickness direction of the pipe. [Explanation of symbols]

[0033] 1. Winged pile (embodiment) 3 Steel pipe 5 flat wing 7 Slanted end face 11 Winged steel pipe pile (conventional example) 13 Flat surface S Gap

Claims

1. A method for manufacturing a winged pile, comprising the steps of: attaching a flat plate wing having a diameter larger than the diameter of a cylindrical pipe to a tip surface of the pipe in a state inclined in the axial direction relative to the central axis of the pipe; a step of forming an inclined end surface on a tip end surface of the tube that is in contact with an upper surface of the flat plate blade, the tip end surface being inclined in the axial direction and also inclined in the radial direction; a blade joining step for joining the upper surface of the flat plate blade to the inclined end surface by abutting the upper surface of the flat plate blade, The inclined end face forming step is a manufacturing method for a winged pile, in which the inclined end face is formed so that the radial inclination angle changes depending on the circumferential position, and the upper surface of the flat plate wing abuts against the entire surface of the inclined end face in the plate thickness direction.

2. A method for manufacturing a winged pile as described in claim 1, wherein, when the inclined end face forming step is performed by manual gas cutting, cutting lines are set around the entire circumference of the inner and outer surfaces of the pipe, and the cutting line on the inner surface of the pipe and the cutting line on the outer surface of the pipe are cut so as to connect in the thickness direction of the pipe.

3. A method for designing a winged pile in which a flat plate wing having a diameter larger than the diameter of a cylindrical pipe is attached to the tip surface of the pipe in a state inclined in the axial direction relative to the central axis of the pipe, a radially inclined end surface is provided on a tip end surface of the tube that is inclined in the axial direction and inclined in the radial direction, the tip end surface being inclined in the axial direction and inclined in the radial direction, The upper surface of the flat plate wing is abutted against and joined to the inclined end surface, This is a design method for a winged pile in which the inclined end face is set so that the radial inclination angle of the inclined end face changes depending on the circumferential position, and the upper surface of the flat plate wing abuts against the entire surface of the inclined end face in the plate thickness direction.

4. The design method for a winged pile as described in claim 3, wherein the inclined end face is set by setting an inner pipe surface line around the entire circumference on the inner pipe side and an outer pipe surface line around the entire circumference on the outer pipe side, and setting the inner pipe surface line and the outer pipe surface line so as to connect them in the thickness direction of the pipe.

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