Steel pipe pile connection structure and manufacturing method for steel pipe pile connection structure

Abstract

To provide a steel pipe pile connection structure and a manufacturing method for a steel pipe pile connection structure, which can increase the connection strength of steel pipe piles arranged above and below.SOLUTION: A connection structure includes a cylindrical first joint part 30 provided concentrically with a lower steel pipe pile 10, and a cylindrical second joint part 60 provided concentrically with an upper steel pipe pile 20. The first joint part 30 includes a base end cylindrical part 31 and a tip end cylindrical part 40 that protrudes toward the second joint part 60 side from the base end cylindrical part 31. A weld recess 53 is formed in a ring member 50 provided at an end of the tip end cylindrical part 40. A main weld part 57, which is a welded part between the base end cylindrical part 31 and the ring member 50, is formed between the base end cylindrical part 31 and the weld recess 53.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a steel pipe pile connection structure and a manufacturing method thereof. [Background technology]

[0002] When constructing a structure on soft ground, a pile foundation is used to support the structure. In a pile foundation, the tip of a cylindrical steel pipe pile needs to reach the supporting layer below the soft ground. Therefore, a construction method is used in which a steel pipe pile equipped with a drilling blade is embedded in the ground while rotating, the lower end of a new steel pipe pile is connected to the upper end of the embedded steel pipe pile, and the connected steel pipe pile is embedded while rotating.

[0003] Patent Document 1 discloses a technique for connecting a lower steel pipe pile, which is a steel pipe pile that has been buried earlier, and an upper steel pipe pile, which is a steel pipe pile placed above the lower steel pipe pile. To explain this technique, a cylindrical inside cylinder is joined to the upper end of the lower steel pipe pile, and a cylindrical outside cylinder that fits into the inside cylinder from the outside is joined to the lower end of the upper steel pipe pile.

[0004] Each of the inside cylinder and the outside cylinder has a through hole formed therein that penetrates from the outer peripheral surface of the outside cylinder to the inner peripheral surface of the inside cylinder when the outside cylinder and the inside cylinder are fitted together. A truncated cone-shaped taper lock portion is fitted into the through hole of each cylinder, thereby connecting the inside cylinder and the outside cylinder. When the upper steel pipe pile is rotated in the connected state, the rotational torque acting on the upper steel pipe pile is transmitted to the lower steel pipe pile, causing the lower steel pipe pile to also rotate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6243814 Summary of the Invention [Problem to be solved by the invention]

[0006] The outside cylinder and the upper steel pipe pile are joined by welding the upper end of the outside cylinder to the outer periphery of the upper steel pipe pile. In this case, the length of the weld between the upper steel pipe pile and the outside cylinder in the axial direction of the upper steel pipe pile becomes short, and the joint strength between the upper steel pipe pile and the outside cylinder may become insufficient. As a result, the connection strength between the upper steel pipe pile and the lower steel pipe pile may become insufficient.

[0007] The present disclosure has been made in consideration of the above-mentioned circumstances, and aims to provide a steel pipe pile connection structure that can increase the connection strength of steel pipe piles arranged above and below, and a method for manufacturing a steel pipe pile connection structure. [Means for solving the problem]

[0008] The present disclosure relates to a steel pipe pile connection structure that connects the ends of cylindrical steel pipe piles arranged vertically, In a first steel pipe pile, which is one of the steel pipe piles arranged above and below, a cylindrical first joint portion is provided at an axial end of the first steel pipe pile so as to be concentric with the first steel pipe pile; In a second steel pipe pile, which is the other of the steel pipe piles arranged above and below, a cylindrical second joint portion is provided at an axial end of the second steel pipe pile so as to be concentric with the second steel pipe pile; Equipped with The first joint portion is A base end cylindrical portion provided at an axial end portion of the first steel pipe pile; a connecting cylindrical portion provided concentrically with the base end cylindrical portion on either the inner or outer radial side of the base end cylindrical portion and protruding toward the second joint portion beyond the base end cylindrical portion; Equipped with When the second joint portion is fitted to the connecting cylindrical portion, the first steel pipe pile and the second steel pipe pile are concentric, In the fitted state, a through hole is formed radially penetrating each of the connecting cylindrical portion and the second joint portion, A connecting member is provided which is inserted into the through holes of the connecting cylindrical portion and the second joint portion to connect the connecting cylindrical portion and the second joint portion.

[0009] In the present disclosure, a weld recess is formed at an end portion of the connecting cylindrical portion on the base end side in the axial direction, the weld recess being spaced away from the base end cylindrical portion and opening toward the base end side, A main weld portion, which is a welded portion between the base end cylindrical portion and the connecting cylindrical portion, is formed between the base end cylindrical portion and the weld recess.

[0010] Since the weld recess is formed, the length of the welded portion between the base end cylindrical portion and the connecting cylindrical portion in the axial direction can be increased. This increases the joint strength between the base end cylindrical portion and the connecting cylindrical portion. As a result, the connection strength between the first steel pipe pile and the second steel pipe pile via the first joint portion and the second joint portion that include the base end and connecting cylindrical portion, and the connecting member can be increased. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a front view of a pair of steel pipe piles arranged above and below according to the first embodiment. [Diagram 2] FIG. 4 is a front view of the first and second joint parts mated together. [Diagram 3] Cross-sectional view taken along line 3-3 in Figure 2. [Figure 4] FIG. 4 is a view of the second joint portion as seen from above in the axial direction. [Diagram 5] Cross-sectional view taken along line 5-5 in Figure 2. [Figure 6] FIG. [Figure 7] 7 is a cross-sectional view taken along line 7-7 in FIG. 3, showing a state in which the sleeve is fitted into the through hole. [Figure 8] FIG. [Figure 9] 11A and 11B are diagrams showing a fitting process of the ring member and the tip side cylindrical portion. [Figure 10] 13A and 13B are diagrams showing a fitting process of the ring member and the tip side cylindrical portion. [Figure 11] 6A and 6B are diagrams showing a welding process for the ring member and the tip side cylindrical portion. [Figure 12] 13A and 13B are diagrams showing a fitting process of the connecting cylindrical portion and the base end cylindrical portion. [Figure 13] 13A and 13B are diagrams showing a fitting process of the connecting cylindrical portion and the base end cylindrical portion. [Figure 14] 6A and 6B are diagrams showing a welding process for the connecting cylindrical portion and the base end cylindrical portion. [Figure 15] 13A and 13B are diagrams showing a process of joining a base plate to a tip side cylindrical portion. [Figure 16] FIG. 11 is a vertical cross-sectional view of first and second joint parts fitted together according to the second embodiment. [Figure 17] FIG. 11 is a vertical cross-sectional view of a first joint portion according to another embodiment. [Figure 18] FIG. 11 is a vertical cross-sectional view of a first joint portion according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] First Embodiment Hereinafter, a first embodiment of the steel pipe pile connection structure according to the present disclosure will be described with reference to the drawings. As shown in FIG. 1, the connection structure connects a steel pipe pile buried in the ground first with a steel pipe pile buried after the first steel pipe pile. Hereinafter, of the pair of steel pipe piles arranged vertically, the one arranged on the lower side will be referred to as the lower steel pipe pile 10, and the one arranged on the upper side will be referred to as the upper steel pipe pile 20. Of the multiple steel pipe piles arranged vertically, a drilling bit DB and a wing expansion DW are provided at the lower end of the lowest steel pipe pile. The wing expansion DW is semicircular, and multiple (two are illustrated) are provided at the lower end of the steel pipe pile.

[0013] 2 and 3, the lower steel pipe pile 10 and the upper steel pipe pile 20 are cylindrical. The outer diameter of the lower steel pipe pile 10 is the same as the outer diameter of the upper steel pipe pile 20. In addition, the thickness of the lower steel pipe pile 10 is the same as the thickness of the upper steel pipe pile 20.

[0014] The connection structure of the lower steel pipe pile 10 and the upper steel pipe pile 20 includes a first joint section 30 and a second joint section 60. In this embodiment, the first joint section 30 is an inner joint section, and is provided at the upper end section of each steel pipe pile 10, 20. The second joint section 60 is an outer joint section, and is provided at the lower end section of each steel pipe pile 10, 20. Among the multiple steel pipe piles arranged in the vertical direction, the lowermost steel pipe pile is provided with a wing expansion DW or the like, and therefore is not provided with the second joint section 60.

[0015] The first joint part 30 is a steel member. As shown in Figs. 2 to 5, the first joint part 30 includes a base end side cylindrical part 31 and a tip end side cylindrical part 40 each having a cylindrical shape. The outer diameter dimension of the base end side cylindrical part 31 is the same as the outer diameter dimension of the lower steel pipe pile 10. The radial thickness dimension of the base end side cylindrical part 31 is the same as the radial thickness dimension of the lower steel pipe pile 10. With the lower end surface of the base end side cylindrical part 31 and the upper end surface of the lower steel pipe pile 10 in contact with each other, the lower end of the base end side cylindrical part 31 and the upper end of the lower steel pipe pile 10 are joined by welding. Specifically, for example, the lower end of the base end side cylindrical part 31 and the upper end of the lower steel pipe pile 10 are joined by welding over the entire circumferential area. As a result, the base end side cylindrical part 31 is concentric with the lower steel pipe pile 10. In addition, in FIG. 3 etc., the welded portion between the base end side cylindrical portion 31 and the lower steel pipe pile 10 is omitted from illustration.

[0016] The outer diameter of the tip side cylindrical portion 40 is slightly smaller than the inner diameter of the base side cylindrical portion 31. The tip side cylindrical portion 40 is provided radially inside the base side cylindrical portion 31 so as to be concentric with the base side cylindrical portion 31. The tip side cylindrical portion 40 extends beyond the axial end face of the base side cylindrical portion 31 toward the second joint portion 60. A method of fixing the tip side cylindrical portion 40 to the base side cylindrical portion 31 will be described in detail later.

[0017] The second joint part 60 is a steel member and has a cylindrical shape. The outer diameter of the second joint part 60 is the same as the outer diameter of the first joint part 30. The radial thickness of the second joint part 60 is the same as the radial thickness of the upper steel pipe pile 20. With the upper end surface of the second joint part 60 and the lower end surface of the upper steel pipe pile 20 in contact with each other, the upper end of the second joint part 60 and the lower end of the upper steel pipe pile 20 are joined by welding. Specifically, for example, the upper end of the second joint part 60 and the lower end of the upper steel pipe pile 20 are joined by welding over the entire circumferential area. As a result, the second joint part 60 is concentric with the upper steel pipe pile 20. Note that in FIG. 3 and the like, the welded portion between the second joint part 60 and the upper steel pipe pile 20 is omitted from the illustration.

[0018] 2, a protrusion 33 that protrudes axially toward the second joint portion 60 is formed on the axial end of the base end cylindrical portion 31 that constitutes the first joint portion 30. In this embodiment, the protrusion 33 is formed over 1 / 2 of the length dimension of the base end cylindrical portion 31 in the circumferential direction.

[0019] As shown in Figs. 2 and 5, a recess 61 is formed at the axial end of the second joint part 60, which is recessed toward the opposite side to the first joint part 30 in the axial direction and is fitted into the protrusion 33. In this embodiment, the recess 61 is formed over half the circumferential length of the second joint part 60. In other words, the circumferential length of the recess 61 is the same as the circumferential length of the protrusion 33. The axial recess dimension of the recess 61 relative to the lower end surface of the second joint part 60 is the same as the axial protrusion dimension of the protrusion 33 relative to the upper end surface of the base end side cylindrical part 31. Note that O in Figs. 4 and 5 indicates the central axis of the second joint part 60.

[0020] The inner diameter of the second joint part 60 is slightly larger than the outer diameter of the tip side cylindrical part 40. This allows the second joint part 60 to be gap-fitted into the tip side cylindrical part 40. The tip side cylindrical part 40 serves as a guide part for fitting the protrusion 33 into the recess 61. This guide part is fitted into the second joint part 60 from the outside, and the protrusion 33 is fitted into the recess 61. This brings the upper end surface of the protrusion 33 into close contact with the recess 61.

[0021] An inner through hole 41 is formed in the tip side cylindrical portion 40 constituting the first joint portion 30. A plurality of inner through holes 41 (eight are illustrated) are formed and arranged at equal intervals in the circumferential direction of the tip side cylindrical portion 40. Each inner through hole 41 has the same shape and is formed at the same position in the axial direction of the tip side cylindrical portion 40.

[0022] The second joint part 60 has outer through holes 62. The outer through holes 62 are arranged at equal intervals in the circumferential direction of the second joint part 60, and the number of the outer through holes 62 is the same as the number of the inner through holes 41. The outer through holes 62 have the same shape and are formed at the same position in the axial direction of the second joint part 60. The convex part 33 is fitted into the concave part 61 so that one of the inner through holes 41 and one of the outer through holes 62 are aligned. As a result, eight through holes 41, 62 are formed that penetrate from the outer peripheral surface of the second joint part 60 to the inner peripheral surface of the tip side cylindrical part 40.

[0023] The engagement between the projection 33 of the first joint part 30 and the recess 61 of the second joint part 60 determines the axial and circumferential positions of the second joint part 60 relative to the first joint part 30. This makes it possible to suppress misalignment between the central axis of the inner through hole 41 of the first joint part 30 and the central axis of the outer through hole 62 of the second joint part 60, and makes it possible to make the inner circumferential surfaces of the through holes 41, 62 as continuous as possible from the outer circumferential surface of the second joint part 60 to the inner circumferential surface of the tip side cylindrical part 40. As a result, it becomes easier to insert a sleeve 70, which will be described later, into each of the through holes 41, 62.

[0024] In this embodiment, each of the through holes 41, 62 has a circular shape. The central axis of the inner through hole 41 extends in the radial direction of the first joint part 30, and the inner through hole 41 is formed so that the opening area becomes smaller toward the radially inward side. The central axis of the outer through hole 62 extends in the radial direction of the second joint part 60, and the outer through hole 62 is formed so that the opening area becomes smaller toward the radially inward side.

[0025] As shown in Figs. 6 to 8, the connection structure includes a sleeve 70. In this embodiment, the sleeve 70 is a steel member and is fitted into the through holes 41, 62. The cross-sectional area of ​​the sleeve 70 decreases toward the radial inside of each joint part 30, 60, and the sleeve 70 has a truncated cone shape with the radial direction of each joint part 30, 60 as the height direction. That is, in the sleeve 70, when the radially inner end face is the leading end face 71 and the radially outer end face is the rear end face 72, the leading end face 71 and the rear end face 72 are connected by a cone surface 73. The rear end face 72 may be, for example, an arcuate surface that is convex toward the radially outward. In this case, it is sufficient that the curvature of the arcuate surface of the rear end face 72 and the curvature of the outer circumferential surface of the second joint part 60 are the same. Furthermore, corners of the sleeve 70, such as the periphery of the cone surface 73, may be chamfered (specifically, for example, C-chamfered, R-chamfered or light-chamfered).

[0026] The cross-sectional shape of the sleeve 70 is the same as that of each of the through holes 41, 62. Therefore, when the sleeve 70 is fitted into the through holes 41, 62, the cone surface 73 of the sleeve 70 comes into close contact with the inner peripheral surface of the through holes 41, 62. This allows the rotational torque acting on the second joint portion 60 via the upper steel pipe pile 20 to be accurately transmitted to the lower steel pipe pile 10 via the first joint portion 30.

[0027] A bolt insertion hole 74 is formed in the center of the sleeve 70, penetrating in a direction perpendicular to the cross section of the sleeve 70 (i.e., in the radial direction of each joint portion 30, 60). The length of the sleeve 70 in the direction in which the bolt insertion hole 74 extends is approximately the same as the total thickness of the second joint portion 60 and the tip side cylindrical portion 40.

[0028] A bolt 80 is inserted through the bolt insertion hole 74. The bolt 80 has a shaft portion 81 and a head portion 82. A male thread is formed on the outer periphery of the shaft portion 81. The bolt 80 is inserted through the bolt insertion hole 74 with the head portion 82 facing radially outward of each joint portion 30, 60 and the shaft portion 81 facing radially inward. The head portion 82 abuts against the rear end surface 72 of the sleeve 70 via a washer 83. The rear end surface 72 may be formed with a recess in which the head portion 82 of the bolt 80 is accommodated. This prevents the head portion 82 from protruding from the outer periphery of the second joint portion 60.

[0029] 3 and 7, a base plate 90 is provided at positions on the inner circumferential surface of the tip side cylindrical portion 40 that correspond to the inner through-holes 41. The base plate 90 is made of steel.

[0030] The base plate 90 has a rectangular shape, specifically, a rectangular shape that is long in the circumferential direction of the tip side cylindrical portion 40. The length dimension of the base plate 90 in the circumferential direction of the tip side cylindrical portion 40 is greater than the length dimension of the inner through hole 41 in the circumferential direction of the tip side cylindrical portion 40. In a state in which the base plate 90 straddles the inner through hole 41 in the circumferential direction of the inner through hole 41, both ends of the first surface of the base plate 90 and the inner circumferential surface of the tip side cylindrical portion 40 are in contact with each other. In this contact state, both ends of the base plate 90 in the longitudinal direction are joined to the inner circumferential surface of the tip side cylindrical portion 40 by welding. Note that in FIG. 3 and the like, the welded portion between the base plate 90 and the tip side cylindrical portion 40 is omitted from the illustration. In this embodiment, the sleeve 70, the bolt 80, the washer 83, the base plate 90, and the nut 92 correspond to the "connecting member".

[0031] An insertion hole 91 through which the shaft portion 81 of the bolt 80 is inserted is formed in the center of the base plate 90. In the base plate 90, a first surface and a second surface which is the reverse surface of the first surface are flat surfaces. A nut 92 into which the male thread of the shaft portion 81 is screwed is fixed to the periphery of the insertion hole 91 in the second surface of the base plate 90. The central axis of the insertion hole 91 and the central axis of the inner through hole 41 are the same. The opening area of ​​the insertion hole 91 is smaller than the opening area of ​​the innermost inner through hole 41 in the radial direction.

[0032] 7, the sleeve 70 is inserted into the through holes 41, 62 until the tip surface 71 of the sleeve 70 abuts against the first surface of the base plate 90. This causes the sleeve 70 to fit into the through holes 41, 62, and the conical surface 73 of the sleeve 70 comes into close contact with the inner circumferential surface of the through holes 41, 62. Since the cross-sectional area of ​​the sleeve 70 decreases radially inward, it is easy to insert the sleeve 70 into the through holes 41, 62.

[0033] Next, a manufacturing method for a steel pipe pile connection structure will be described with reference to Figs.

[0034] First, as shown in Fig. 9, the ring member 50 is fitted to the tip side cylindrical portion 40. The ring member 50 includes an annular portion 51 having a circular ring shape and a cylindrical backing metal portion 52. A welding recess 53 that is radially recessed from the axial tip of the annular portion 51 over a predetermined length in the axial direction, and a protruding portion 54 that is adjacent to the welding recess 53 in the axial direction and protrudes in the radial direction are formed on the radial outside of the annular portion 51. The backing metal portion 52 is a portion that extends in the axial direction from the protruding portion 54. The radial thickness of the protruding portion 54 is greater than the radial thickness of the tip side cylindrical portion 40.

[0035] As shown in Fig. 10, while separating the protruding portion 54 of the annular portion 51 from the tip side cylindrical portion 40 in the axial direction, the backing metal portion 52 is fitted to the inner peripheral side of the tip side cylindrical portion 40 so that the welding recessed portion 53 faces radially outward. The axial end portion of the tip side cylindrical portion 40 is a groove portion 40a having a tapered shape in which the outer diameter dimension becomes smaller toward the end in the axial direction. The angle α (see Fig. 9) of the inclined surface of the groove portion 40a with respect to the axial end face of the tip side cylindrical portion 40 is an acute angle, specifically, 20° to 40°, or 25° to 35°, for example, 30°.

[0036] 11, the groove portion 40a of the tip side cylindrical portion 40 with the backing metal portion 52 fitted thereto is welded (specifically, fully penetrated welded) to the annular portion 51. This forms a sub-weld 56, which is a welded portion between the annular portion 51 and the tip side cylindrical portion 40. As a result, a connecting cylindrical portion 55, which is the ring member 50 and the tip side cylindrical portion 40 integrated via the sub-weld 56, is manufactured. The sub-weld 56 is formed over the entire circumferential area of ​​the annular portion 51 and the tip side cylindrical portion 40. If the sub-weld 56 protrudes radially outward from the outer circumferential surface of the tip side cylindrical portion 40, a process of grinding off the protruding portion of the sub-weld 56 with a grinding device such as a grinder may be performed.

[0037] For example, with the axial direction of the tip side cylindrical portion 40 horizontal, the tip side cylindrical portion 40 and the ring member 50 can be rotated around the axial direction while holding a welding rod above the groove portion 40a of the tip side cylindrical portion 40 and arc welding the groove portion 40a and the annular portion 51.

[0038] Next, as shown in Figures 12 and 13, the base end side cylindrical portion 31 protrudes toward the second joint portion 60, and the connecting cylindrical portion 55 is fitted into the radially inner side of the base end side cylindrical portion 31 so that the protruding portion 54 abuts the inner surface of the base end side cylindrical portion 31.

[0039] The welding recess 53 has a tapered shape with a slope whose outer diameter dimension increases (i.e., the radial recess dimension decreases) toward the backing metal portion 52 in the axial direction. This makes it easier to fit the connecting cylindrical portion 55 into the base end cylindrical portion 31. The angle β (see FIG. 9) of the slope of the welding recess 53 with respect to the axial direction of the backing metal portion 52 is an acute angle, and is specifically 20° to 45°, or 25° to 35°, for example 30°.

[0040] 13, in a state in which the connecting cylindrical portion 55 is fitted into the base-end cylindrical portion 31, the inclined surface of the welding recess 53 is separated from the inner circumferential surface of the base-end cylindrical portion 31. Moreover, one axial side of the welding recess 53 is open, and the other axial side is closed by the inner circumferential surface of the base-end cylindrical portion 31 and the protrusion 54.

[0041] 14, the welding recess 53 of the connecting cylindrical portion 55 fitted into the base end cylindrical portion 31 is welded (specifically, partial penetration welding) to the base end cylindrical portion 31. This forms a main weld 57, which is a welded portion between the annular portion 51 and the base end cylindrical portion 31. As a result, the connecting cylindrical portion 55 and the base end cylindrical portion 31 are integrated to manufacture the first joint portion 30. The main weld 57 is formed over the entire circumferential area of ​​the annular portion 51 and the base end cylindrical portion 31.

[0042] By forming the welding recess 53 in a tapered shape, the welding portion can be reduced as much as possible, and the welding operation time can be shortened, which reduces the load of the welding operation.

[0043] For example, with the axial directions of the connecting cylindrical portion 55 and the base end cylindrical portion 31 oriented vertically, the welding recess 53 and the base end cylindrical portion 31 may be arc-welded while a welding rod is held above the welding recess 53. This prevents the molten metal from accumulating in the portion sandwiched between the welding recess 53 and the base end cylindrical portion 31 and spilling out during the welding operation.

[0044] 15, the base plate 90 to which the nut 92 is fixed is fixed to the inner circumferential surface of the tip side cylindrical portion 40 by welding.

[0045] The steel pipe piles 10, 20, with the joints 30, 60 welded together in the factory, are transported to the site where the steel pipe piles are to be buried. At the site, the second joint 60 joined to the upper steel pipe pile 20 is fitted from the outside into the first joint 30 joined to the lower steel pipe pile 10 (see FIG. 6). This makes it possible to suppress radial protrusion of the first and second joints 30, 60. As a result, when the steel pipe pile is buried, it is possible to reduce the load acting on the steel pipe pile and to suppress the joints 30, 60 of the steel pipe pile from disturbing the ground during burial.

[0046] Then, the sleeve 70 is inserted into each of the through holes 41, 62. Thereafter, with the head 82 of the bolt 80 facing radially outward, the bolt 80 with the washer 83 attached is inserted into the bolt insertion hole 74 of the sleeve 70, and the tip of the shaft portion 81 is screwed into the female thread of the nut 92 through the insertion hole 91. As a result, the sleeve 70 is pressed radially inward by the head 82 of the bolt 80, and the first joint portion 30 and the second joint portion 60 are firmly fixed together. As a result, the upper steel pipe pile 20 and the lower steel pipe pile 10 are firmly fixed together.

[0047] During the burying operation, when the upper steel pipe pile 20 and the lower steel pipe pile 10 are connected via the first joint 30, the second joint 60, and the sleeve 70, and the steel pipe piles 10, 20 are rotated, a torsional moment acts on the base end cylindrical portion 31 and the tip end cylindrical portion 40. Here, in this embodiment, since the weld recess 53 is formed, the length of the main weld portion 57 between the base end cylindrical portion 31 and the connecting cylindrical portion 55 in the axial direction can be increased. This can increase the joint strength between the base end cylindrical portion 31 and the connecting cylindrical portion 55. As a result, the connection strength between the lower steel pipe pile 10 and the upper steel pipe pile 20 via the first joint 30, the second joint 60, and the sleeve 70 can be increased.

[0048] If the radial thickness dimension tb of the tip side cylindrical portion 40 is small, a problem may occur in that the first joint portion 30 including the base end side cylindrical portion 31 and the tip side cylindrical portion 40 may be damaged. If the thickness dimension is increased over the entire axial area of ​​the tip side cylindrical portion 40 to address this problem, the weight of the tip side cylindrical portion 40 will increase significantly.

[0049] 14, a radial thickness dimension ta from the inner circumferential surface of the base end cylindrical portion 31 to the inner circumferential surface of the annular portion 51 constituting the ring member 50, via the main welded portion 57, is larger than a radial thickness dimension tb of the tip end cylindrical portion 40. This makes it possible to increase the thickness dimension at the welded portion of the connecting cylindrical portion 55, and suppresses the occurrence of a situation in which the weight of the tip end cylindrical portion 40 increases significantly while suppressing the occurrence of a situation in which the first joint portion 30 is damaged.

[0050] For example, when the tip side cylindrical portion 40 is made of a drawn steel pipe, increasing the wall thickness of only the axial end of the tip side cylindrical portion 40 leads to inconveniences such as an increase in the processing load. Also, for example, manufacturing the tip side cylindrical portion 40 and the ring member 50 as a single member by cutting or the like also leads to inconveniences such as an increase in the processing load. In contrast, a method using the ring member 50 that is a separate member from the tip side cylindrical portion 40 makes it possible to increase the joining strength between the base side cylindrical portion 31 and the connecting cylindrical portion 55 while suppressing an increase in the processing load.

[0051] <Second embodiment> The second embodiment will be described below with reference to the drawings, focusing on the differences from the first embodiment. In this embodiment, as shown in Fig. 16, the first joint part 130 constituting the connecting structure is not an inner joint part but an outer joint part. Fig. 16 corresponds to Fig. 3.

[0052] The first joint part 130 includes a base end side cylindrical part 131 and a tip end side cylindrical part 140, each of which has a cylindrical shape. The inner diameter dimension of the tip end side cylindrical part 140 is slightly larger than the outer diameter dimension of the base end side cylindrical part 131. The tip end side cylindrical part 140 is provided radially outward of the base end side cylindrical part 131 so as to be concentric with the base end side cylindrical part 131. The tip end side cylindrical part 140 extends toward the second joint part 60 beyond the axial end face of the base end side cylindrical part 131. Note that, at the axial end part of the base end side cylindrical part 131, a convex part is formed to be fitted into the concave part 61 of the second joint part 60, as in the first embodiment.

[0053] The outer diameter of the second joint part 60 is slightly smaller than the inner diameter of the tip side cylindrical part 140. This allows the second joint part 60 to be fitted into the tip side cylindrical part 140 in a gap fit. The tip side cylindrical part 140 constituting the first joint part 130 has a plurality of inner through holes 141 formed therein, as in the first embodiment. A sleeve 70 is fitted into each of the through holes 141, 62. In this embodiment, the base plate 90 is welded to the inner peripheral surface of the second joint part 60.

[0054] Next, a manufacturing method for a steel pipe pile connection structure will be described.

[0055] The ring member 150 of this embodiment includes an annular portion 151 having a circular ring shape and a cylindrical backing metal portion 152. A welding recess 153 that is radially recessed from the axial tip of the annular portion 151 over a predetermined length in the axial direction, and a protruding portion 154 that is adjacent to the welding recess 153 in the axial direction and protrudes in the radial direction are formed on the radially inner side of the annular portion 151. The backing metal portion 152 is a portion that extends axially from the protruding portion 154.

[0056] While separating the protruding portion 154 of the annular portion 151 from the tip side cylindrical portion 140 in the axial direction, the backing metal portion 152 is fitted to the outer periphery of the tip side cylindrical portion 140 so that the welding recess 153 faces radially inward. The axial end of the tip side cylindrical portion 140 is a groove portion 140a having a tapered shape whose inner diameter dimension decreases radially inward.

[0057] Next, the groove portion 140a of the tip side cylindrical portion 140 with the backing metal portion 152 fitted thereto is welded (specifically, by full penetration welding) to the annular portion 151. This forms a sub-weld 156, which is a welded portion between the annular portion 151 and the tip side cylindrical portion 140. As a result, a connected cylindrical portion is manufactured, which is the ring member 150 and the tip side cylindrical portion 140 integrated via the sub-weld 156. The sub-weld 156 is formed over the entire circumferential area of ​​the annular portion 151 and the tip side cylindrical portion 140.

[0058] Next, the base end cylindrical portion 131 protrudes toward the second joint portion 60 side, and the connecting cylindrical portion is fitted to the radial outside of the base end cylindrical portion 131 so that the protrusion 154 abuts the outer peripheral surface of the base end cylindrical portion 131.

[0059] The welding recess 153 has a tapered shape with a slope whose inner diameter dimension becomes smaller (i.e., the radial recess dimension becomes smaller) toward the backing metal portion 152 in the axial direction. This makes it easier to fit the connecting cylindrical portion into the base end cylindrical portion 131. One axial side of the welding recess 153 is open.

[0060] Thereafter, the welding recess 153 of the connecting cylindrical portion fitted into the base end cylindrical portion 131 is welded (specifically, partial penetration welding) to the base end cylindrical portion 131. This forms a main weld 157, which is a welded portion between the annular portion 151 and the base end cylindrical portion 131. As a result, the connecting cylindrical portion and the base end cylindrical portion 131 are integrated to manufacture the first joint portion 130. The main weld 157 is formed over the entire circumferential area of ​​the annular portion 151 and the base end cylindrical portion 131.

[0061] <Other embodiments> Each of the above embodiments may be modified as follows.

[0062] The ring member is not limited to one having a tapered weld recess. For example, taking the first embodiment as an example, as shown in Fig. 17, the ring member 250 may have an annular portion 251 having a stepped weld recess 253, a backing metal portion 252, and a protrusion 254. The weld recess 253 opens to one axial side.

[0063] The joining of the tip cylindrical portion and the ring member is not limited to welding, and may be, for example, as described below.

[0064] In the first method, a bolt insertion hole is formed in the backing metal portion of the ring member so as to penetrate radially, and a female threaded hole is formed in the tip cylindrical portion. A plurality of bolt insertion holes are formed in a line in the circumferential direction. The male threads of the shafts of the bolts inserted into the bolt insertion holes of the ring member are screwed into the female threaded hole of the tip cylindrical portion, thereby joining the tip cylindrical portion and the ring member.

[0065] Regarding the second method, a recess that is recessed in the axial direction is formed at the axial end of the tip side cylindrical portion. A plurality of recesses may be formed lined up in the circumferential direction. The ring member is formed with a protrusion that protrudes in the axial direction instead of a backing metal portion. The tip side cylindrical portion and the ring member are joined by fitting (e.g., interference fit) the protrusion formed on the ring member into the recess formed on the tip side cylindrical portion.

[0066] In each of the above embodiments, the tip side cylindrical portion is first welded to the ring member 50, but this is not limited thereto. First, the tip side cylindrical portion and the base side cylindrical portion are welded together to integrate the tip side cylindrical portion and the base side cylindrical portion at the auxiliary weld. Then, a ring member without a backing metal portion is brought into contact with the auxiliary weld, and the weld recess and the base side cylindrical portion are welded together to integrate the ring member and the base side cylindrical portion at the main weld. In addition, the tip side cylindrical portion and the ring member are welded together to integrate the tip side cylindrical portion and the ring member at the auxiliary weld. In this case, the auxiliary weld is integrated with the base side cylindrical portion, and the strength can be further increased.

[0067] In each of the above embodiments, the number of protruding portions is not limited to one, and multiple protruding portions may be formed at equal intervals in the circumferential direction of the first joint part. In this case, the number of recessed portions formed in the second joint part may be the same as the number of protruding portions.

[0068] The connecting members of the first and second joint parts are not limited to sleeves, and may be, for example, bolts and nuts.

[0069] As shown in FIG. 18, a ring member may not be used to join the tip side cylindrical portion 40 and the base side cylindrical portion 31. In this case, the tip side cylindrical portion 40 and the base side cylindrical portion 31 may be integrated by the main weld 257. More specifically, a radially recessed weld recess 42 is formed at the axial end of the tip side cylindrical portion 40. The weld recess 42 is separated from the inner circumferential surface of the base side cylindrical portion 31 and opens at one axial end side. The weld recess 42 has a tapered shape having a slope whose outer diameter dimension becomes larger (i.e., the radial recess dimension becomes smaller) toward the second joint portion 60 in the axial direction. The weld recess 42 of the tip side cylindrical portion 40 and the base side cylindrical portion 31 are welded (for example, by partial penetration welding) to form the main weld 257 between the weld recess 42 and the base side cylindrical portion 31, and a connected cylindrical portion in which the tip side cylindrical portion 40 and the base side cylindrical portion 31 are integrated is manufactured. The main weld 257 is formed over the entire circumferential area between the tip side cylindrical portion 40 and the base side cylindrical portion 31. The configuration in which the tip side cylindrical portion and the base side cylindrical portion are welded together is not limited to the configuration in which the first joint portion is the inner joint portion, and may be applied to the configuration shown in Fig. 16 in which the first joint portion is the outer joint portion.

[0070] The main and auxiliary welds are not limited to those formed over the entire circumferential area, but may be formed over a portion of the circumferential area. For example, the main and auxiliary welds may be formed in a plurality of areas spaced apart from each other at a predetermined interval in the circumferential direction.

[0071] The first joint portion may be provided at the lower end portion of the steel pipe pile, and the second joint portion may be provided at the upper end portion of the steel pipe pile. [Explanation of symbols]

[0072] 10...lower steel pipe pile (first steel pipe pile), 20...upper steel pipe pile (second steel pipe pile), 30...first joint portion, 31...base end cylindrical portion, 40...tip end cylindrical portion, 50...ring member, 60...second joint portion, 70...sleeve.

Claims

1. In a steel pipe pile connection structure that connects the ends of cylindrical steel pipe piles (10, 20) arranged vertically, In a first steel pipe pile (10), which is one of the steel pipe piles arranged above and below, a cylindrical first joint portion (30, 130) is provided at an axial end portion of the first steel pipe pile so as to be concentric with the first steel pipe pile; In the second steel pipe pile (20), which is the other of the steel pipe piles arranged above and below, a cylindrical second joint portion (60) is provided at the axial end of the second steel pipe pile so as to be concentric with the second steel pipe pile; Equipped with The first joint portion is A base end cylindrical portion (31, 131) provided at the axial end portion of the first steel pipe pile; a connecting cylindrical portion (55) provided concentrically with the base end cylindrical portion on either the inner or outer radial side of the base end cylindrical portion and protruding toward the second joint portion beyond the base end cylindrical portion; Equipped with When the second joint portion is fitted to the connecting cylindrical portion, the first steel pipe pile and the second steel pipe pile are concentric, In the fitted state, a through hole (41, 62, 141) is formed radially penetrating each of the connecting cylindrical portion and the second joint portion, a connecting member (70, 80, 83, 90, 92) that is inserted into the through hole of each of the connecting cylindrical portion and the second joint portion to connect the connecting cylindrical portion and the second joint portion, a welding recess (53, 153, 253) is formed at an end portion of the connecting cylindrical portion on a base end side in the axial direction, the welding recess (53, 153, 253) being spaced away from the base end cylindrical portion and opening on the base end side, A steel pipe pile connection structure, in which a main weld (57, 157, 257), which is a welded portion between the base end cylindrical portion and the connecting cylindrical portion, is formed between the base end cylindrical portion and the weld recess.

2. The connecting cylindrical portion is a tip end side cylindrical portion (40, 140) provided concentrically with the base end side cylindrical portion and protruding toward the second joint portion beyond the base end side cylindrical portion; an annular portion (51, 151, 251) facing the base end cylindrical portion in the radial direction and having the welding recess formed therein; having The steel pipe pile connection structure according to claim 1 , wherein a radial thickness dimension of the annular portion is greater than a radial thickness dimension of the tip cylindrical portion.

3. a sub-weld (56, 156) which is a welded portion between the annular portion and the tip side cylindrical portion is formed between the annular portion and the tip side cylindrical portion in the axial direction, A steel pipe pile connection structure as described in claim 2, wherein a thickness dimension (ta) from the radial peripheral surface of the base end cylindrical portion on the side of the connecting cylindrical portion to the radial peripheral surface of the annular portion opposite the base end cylindrical portion is greater than a radial thickness dimension (tb) of the tip end cylindrical portion.

4. The outer diameter dimensions of the base end cylindrical portion and the second joint portion are the same, The connecting cylindrical portion is provided radially inside the base end cylindrical portion, The steel pipe pile connection structure according to any one of claims 1 to 3, wherein the second joint portion is fitted to the connecting cylindrical portion from the outside.

5. The manufacturing method of a steel pipe pile connection structure according to any one of claims 1 to 3, wherein the weld recess (53, 153) has a tapered shape having a slope whose recess dimension increases toward the base end in the axial direction.

6. The manufacturing method of a steel pipe pile connection structure according to claim 5, wherein the angle of the inclined surface with respect to the axial direction is 20° to 45°.

7. A protrusion (33) protruding toward the second joint portion in the axial direction is formed on an end portion of the base end cylindrical portion on the second joint portion side in the axial direction, A recess (61) is formed at an end of the second joint part on the side of the first joint part in the axial direction, the recess (61) being recessed toward the opposite side to the first joint part in the axial direction and fitted into the protrusion, When the second joint portion is fitted into the connecting cylindrical portion and the convex portion is fitted into the concave portion, the first steel pipe pile and the second steel pipe pile are concentric, the through hole is formed to radially penetrate the connecting cylindrical portion and the second joint portion when the protrusion is fitted into the recess, In the connecting cylindrical portion and the second joint portion, an opening area of ​​the through hole becomes smaller toward a radially inner side, As the connecting member, a sleeve (70) is provided which has a truncated cone shape whose cross-sectional area decreases toward the radial inside and whose height direction is the radial direction, A steel pipe pile connection structure as described in any one of claims 1 to 3, wherein when the sleeve is inserted into the through hole, the conical surface (73) of the sleeve is in close contact with the inner surface of the through hole in the connecting cylindrical portion and the second joint portion.

8. A method for manufacturing a steel pipe pile connection structure for connecting ends of cylindrical steel pipe piles (10, 20) arranged vertically, The steel pipe pile connection structure is In a first steel pipe pile (10), which is one of the steel pipe piles arranged above and below, a cylindrical first joint portion (30, 130) is provided at an axial end portion of the first steel pipe pile so as to be concentric with the first steel pipe pile; In the second steel pipe pile (20), which is the other of the steel pipe piles arranged above and below, a cylindrical second joint portion (60) is provided at the axial end of the second steel pipe pile so as to be concentric with the second steel pipe pile; Equipped with The first joint portion is A base end cylindrical portion (31, 131) provided at the axial end portion of the first steel pipe pile; A tip side cylindrical portion (40, 140), An annular portion (51, 151, 251); Equipped with The annular portion has a weld recess (53, 153, 253) recessed in a radial direction at an axial end of the annular portion; a protrusion (54, 154, 254) adjacent to the welding recess in the axial direction and protruding in the radial direction; is formed, The annular portion is formed with a cylindrical backing metal portion (52, 152, 252) extending in the axial direction, a step of fitting the backing metal portion into the tip side cylindrical portion while separating the annular portion from the tip side cylindrical portion in the axial direction; a step of welding the front end cylindrical portion into which the backing metal portion is fitted and the annular portion to form a sub-weld portion (56, 156) which is a welded portion between the annular portion and the front end cylindrical portion; a step of fitting the tip side cylindrical portion to either the inner or outer side in the radial direction of the base side cylindrical portion such that a connecting cylindrical portion (55) which is the annular portion and the tip side cylindrical portion integrated via the auxiliary weld portion protrudes toward the second joint portion beyond the base side cylindrical portion and the protruding portion abuts against the base side cylindrical portion; forming a main weld (57, 157, 257) which is a welded portion between the annular portion and the base-end side cylindrical portion by welding the weld recess of the connecting cylindrical portion fitted to the base-end side cylindrical portion and the base-end side cylindrical portion; A manufacturing method for a steel pipe pile connection structure comprising:

9. A method for manufacturing a steel pipe pile connection structure for connecting ends of cylindrical steel pipe piles (10, 20) arranged vertically, The steel pipe pile connection structure is In a first steel pipe pile (10), which is one of the steel pipe piles arranged above and below, a cylindrical first joint portion (30, 130) is provided at an axial end portion of the first steel pipe pile so as to be concentric with the first steel pipe pile; In the second steel pipe pile (20), which is the other of the steel pipe piles arranged above and below, a cylindrical second joint portion (60) is provided at the axial end of the second steel pipe pile so as to be concentric with the second steel pipe pile; Equipped with The first joint portion is A base end cylindrical portion (31, 131) provided at the axial end portion of the first steel pipe pile; A tip side cylindrical portion (40, 140), Equipped with A welding recess (42) recessed in the radial direction is formed at the axial end of the tip side cylindrical portion, a step of fitting the tip side cylindrical portion to either the inner or outer side in the radial direction of the base end side cylindrical portion such that the tip side cylindrical portion protrudes toward the second joint portion more than the base end side cylindrical portion; forming a main weld (257) which is a welded portion between the tip side cylindrical portion and the base end side cylindrical portion by welding the weld recess of the tip side cylindrical portion fitted to the base end side cylindrical portion and the base end side cylindrical portion; A manufacturing method for a steel pipe pile connection structure comprising:

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