Steel pipe joint structure and steel pipe pile

Abstract

To facilitate the work of connecting cylindrical connecting parts to each other.SOLUTION: A key member 20 comprises: a key body 21 having a key intermediate portion 21a located inside each connecting hole 114, 124, 126, and 134; a key inner diameter end portion 21b located on an inner diameter side of the key intermediate portion 21a; and a key outer diameter end portion 21c located on an outer diameter side of the key intermediate portion 21a; an inner diameter side stopper 22 that is supported so as to be capable of projecting and retracting at the key inner diameter end portion 21b, allows radial movement of the key body 21 while the key inner diameter end portion 21b is located in each connecting hole, and comes into a projected state when the key inner diameter end portion 21b moves into an inner hollow portion of lower connecting cylinder portions 122 and 134, thereby restricting movement of the key body 21 toward the outer diameter side; and an outer diameter side stopper 23 that is detachably fixed to the key outer diameter end portion 21c, restricts movement of the key body 21 toward the inner diameter side in a fixed state, and allows movement of the key body 21 toward the inner diameter side in a removed state.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a steel pipe joint structure and a steel pipe pile. [Background technology]

[0002] Long steel pipe piles and columns are constructed by connecting multiple steel pipes of lengths suitable for transportation and work along their axial direction. When constructing a steel pipe pile or column, for example, the connecting tubular portions of one steel pipe are inserted into the connecting tubular portion of the other steel pipe, and the connecting tubular portions are connected to each other. To connect the connecting cylindrical portions together, for example, the connecting cylindrical portions are welded together, or the connecting holes provided in each connecting cylindrical portion are connected to each other, and then a key member acting as a wedge is inserted into each connecting hole that is in a connected state. Although welding the connecting tubular sections together can firmly connect the connecting tubular sections, it is time-consuming and inconvenient because it cannot be done in rainy weather. Furthermore, when the connecting tubular sections need to be disconnected, the welded section must be cut, which makes the work less efficient. On the other hand, the connection work using the key member is simpler than welding work and can be carried out even in rainy weather. Furthermore, the connection state of the connecting tubular parts can be released by removing the key member.

[0003] Patent Document 1 discloses a configuration in which a set of a screw shaft provided with a claw at one end and a nut that is fastened onto the other end of the screw shaft is used as a key member. When using such a key member, the connecting holes in the cylindrical portions must be made sufficiently larger than the thickness of the screw shaft in order to ensure sufficient space for the claws at one end of the screw shaft to pass through. If the gap between each connecting hole and the screw shaft is large, the screw shaft becomes unstable, so in the configuration of Patent Document 1, a metallic cylindrical bushing is attached to the screw shaft to fill the gap between each connecting hole and the screw shaft.

[0004] When connecting cylindrical connecting portions using the key member of Patent Document 1, a bushing and a nut are attached to the other end of the screw shaft in advance to prevent the screw shaft from falling into the steel pipe. The screw shaft is then inserted into each connecting hole from the claw side, and the nut is tightened with the claw moving beyond each connecting hole into the inner space of the cylindrical connecting portion. As the nut is tightened, the bushing moves along the screw shaft and fits into the connecting hole. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-64669 Summary of the Invention [Problem to be solved by the invention]

[0006] In the key member of Patent Document 1, the bushing and nut are positioned on the outer diameter side of the connecting tubular section with the claw moved into the inner cavity of the connecting tubular section, which requires a long screw shaft, which increases the amount of tightening of the nut when connecting the connecting tubular sections, making the connecting work more time-consuming. The present invention has been made in view of the above circumstances, and an object of the present invention is to facilitate the operation of connecting cylindrical connecting portions to each other. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a steel pipe joint structure comprising a first steel pipe having an outer tubular connecting portion at its end, a second steel pipe having an inner tubular connecting portion at its end, and a key member that connects the inner tubular connecting portion with the outer tubular connecting portion when the inner tubular connecting portion is inserted into the outer tubular connecting portion, wherein the outer tubular connecting portion has a plurality of outer-tube-side connecting holes, the inner tubular connecting portion has a plurality of inner-tube-side connecting holes that can communicate with the outer-tube-side connecting holes, and the key member has a key intermediate portion located inside each of the connecting holes when the key member is completely inserted into each of the connecting holes that are in a communicating state. a key body having an inner diameter end portion located on the inner diameter side of the key intermediate portion and an outer diameter end portion located on the outer diameter side of the key intermediate portion; and an inner diameter side stopper that is supported so as to be able to protrude and retract by the key inner diameter end portion, that is in a retracted state that allows radial movement of the key body while the key inner diameter end portion is located in each of the connecting holes, and that protrudes when the key inner diameter end portion moves radially out of each of the connecting holes and into the inner void of the inner connecting cylindrical portion, thereby restricting the outer diameter movement of the key body. [Effects of the Invention]

[0008] According to the present invention, the operation of connecting the connecting tubular portions to each other can be facilitated. [Brief explanation of the drawings]

[0009] [Figure 1] (a) is a diagram showing the lower pile, (b) is a diagram showing the middle pile, (c) is a diagram showing the upper pile, (d) is a perspective view of the key member from the front, and (e) is a perspective view of the key member from the rear. [Figure 2] 1A is a diagram showing the state in which the connecting tube portions are connected to each other, FIG. 1B is a diagram explaining the movement of the key member during the connecting operation, and FIG. 1C is a diagram explaining the movement of the key member during the removal operation. [Figure 3] 1A is a front view of the key member, FIG. 1B is a right side view of the key member, FIG. 1C is a rear view of the key member, and FIG. 1D is a plan view of the key member. [Figure 4] 10 is a view showing a state in which the lower connecting cylindrical portion is inserted into the upper connecting cylindrical portion and the upper connecting hole and the lower connecting hole are communicated with each other. FIG. [Figure 5] 10A and 10B are diagrams showing the insertion direction of key members into the respective connecting holes in a communicating state. [Figure 6] 10A and 10B are diagrams illustrating the operation of connecting the connecting cylindrical portions using a key member, in which (a) shows the state in which the inner diameter end of the key is brought close to the upper connecting hole, (b) shows the state in which the inner diameter end of the key is inserted into the upper connecting hole, (c) shows the state in which the inner diameter end of the key has been moved into the lower connecting hole, and (d) shows the state in which the inner diameter end of the key has been moved to the inner space of the lower connecting cylindrical portion. [Figure 7] 10A and 10B are diagrams illustrating the removal of the key member when the connecting cylindrical parts are separated, in which (a) shows the connecting cylindrical parts connected to each other by the key member, (b) shows the state in which the outer diameter side stopper has been removed from the key body, (c) shows the state in which the key outer diameter end has been moved to the lower connecting hole, and (d) shows the state in which the key member has been dropped into the inner space of the lower connecting cylindrical part. [Figure 8] 1A and 1B are diagrams illustrating the construction procedure for a steel pipe pile, in which (a) shows the lower pile attached to the pile driver, and (b) shows the lower half of the lower pile buried in the ground. [Figure 9] These are diagrams explaining the construction procedure for steel pipe piles, where (a) shows the intermediate pile attached to the pile driver being moved directly above the lower pile, (b) shows the lower connecting tube part of the intermediate pile being inserted into the upper connecting tube part of the lower pile, and (c) shows the insertion of key members into each connecting hole. [Figure 10] These figures explain the construction procedure for steel pipe piles, where (a) shows the state in which the lower half of the intermediate pile has been buried in the ground, and (b) shows the state in which the upper pile attached to the pile driver has been moved directly above the intermediate pile. [Figure 11] These are diagrams explaining the construction procedure for steel pipe piles, where (a) is a diagram showing the steel pipe pile buried in the ground, (b) is a diagram showing the steel pipe pile of the first modified example in which a pile head mounting portion is provided on the upper pile buried in the ground, and (c) is a diagram showing the pile head member attached to the pile head mounting portion of the upper pile in the first modified example. [Figure 12]These are diagrams explaining the procedure for removing steel pipe piles, where (a) shows the main part of the upper pile attached to the pile driver, and (b) shows the upper pile, intermediate pile, and lower pile rotated in opposite directions to expose the upper half of the intermediate pile above ground. [Figure 13] These figures explain the procedure for removing steel pipe piles, where (a) shows the state in which the key member has been dropped into the inner space of the lower connecting tube part of the upper pile, and (b) shows the state in which the upper pile, separated from the intermediate pile, has been pulled up. [Figure 14] (a) is a front view of a key member according to the second modified example, (b) is a right side view of a key member according to the second modified example, (c) is a rear view of a key member according to the second modified example, (d) is a plan view of a key member according to the second modified example, and (e) is a diagram showing an upper connecting hole and a lower connecting hole according to the second modified example. [Figure 15] 10A and 10B are views showing an upper connecting cylinder portion and a lower connecting cylinder portion according to a third modified example. [Figure 16] 10(a) is a horizontal cross-sectional view of a key member according to a fourth modified example, FIG. 10(b) is a vertical cross-sectional view of a key member according to the fourth modified example, and FIG. 10(c) is a horizontal cross-sectional view of a key member according to a fifth modified example. [Figure 17] FIG. 13 is a diagram illustrating a pile main part, a lower connecting tubular part, an upper connecting tubular part, and a key member according to a sixth modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] <Outline of steel pipe joint structure> First, an overview of the steel pipe joint structure will be described. However, unless otherwise specified, the components, types, combinations, shapes, and relative arrangements described in this embodiment are merely illustrative examples and do not intend to limit the scope of this invention. Furthermore, in the following embodiment, a steel pipe pile 1 (see FIG. 11(a)) will be used as an example, but the same can be applied to a steel pipe column. Fig. 1(a) is a diagram showing the lower pile 11, Fig. 1(b) is a diagram showing the intermediate pile 12, Fig. 1(c) is a diagram showing the upper pile 13, Fig. 1(d) is a perspective view of the key member 20 seen from the front, and Fig. 1(e) is a perspective view of the key member 20 seen from the rear. Fig. 2(a) is a diagram showing the connected state of the connecting tube portions, Fig. 2(b) is a diagram explaining the movement of the key member 20 during the connecting work, and Fig. 2(c) is a diagram explaining the movement of the key member 20 during the removal work.

[0011] The lower pile 11 shown in Figure 1(a) comprises a lower pile main part 111, which is the main part of the lower pile 11, a tip blade 112 provided at one end (lower end) of the lower pile main part 111, and an upper connecting tube part 113 (outer connecting tube part) provided at the other end (upper end) of the lower pile main part 111. The lower pile main section 111 is made of, for example, a circular steel pipe. The tip blade 112 is a member for excavating the ground. The upper connecting tube section 113 is part of the joint and is made of, for example, a circular steel pipe with the same diameter as the lower pile main section 111. The upper connecting tube section 113 has multiple upper connecting holes 114 (outer tube side connecting holes) spaced apart circumferentially.

[0012] The intermediate pile 12 shown in Figure 1(b) comprises an intermediate pile main part 121, which is the main part of the intermediate pile 12, a lower connecting tubular part 122 (inner connecting tubular part) provided at one end (lower end) of the intermediate pile main part 121, and an upper connecting tubular part 123 (outer connecting tubular part) provided at the other end (upper end) of the intermediate pile main part 121. The intermediate pile main part 121 is made of, for example, a circular steel pipe. The lower connecting tubular part 122 is part of the joint and is made of, for example, a circular steel pipe with a diameter that allows it to be inserted freely into the inner space of the upper connecting tubular part 113 of the lower pile 11. The lower connecting tubular part 122 is provided with a plurality of lower connecting holes 124 (inner tube side connecting holes) spaced apart in the circumferential direction. The upper connecting tubular part 123 is also part of the joint and is made of, for example, a circular steel pipe with the same diameter as the intermediate pile main part 121. The upper connecting tubular part 123 is provided with a plurality of upper connecting holes 126 (outer tube side connecting holes) spaced apart in the circumferential direction.

[0013] The upper pile 13 shown in Figure 1(c) comprises an upper pile main part 131, which is the main part of the upper pile 13, and a lower connecting tube part 132 (inner connecting tube part) provided at one end (lower end) of the upper pile main part 131. The upper pile main portion 131 is made of, for example, a circular steel pipe. The lower connecting tubular portion 132 is part of the joint and is made of, for example, a circular steel pipe with a diameter that allows it to be inserted into the inner space of the upper connecting tubular portion 123 of the intermediate pile 12. The lower connecting tubular portion 132 is provided with a plurality of lower connecting holes 134 (inner-tube-side connecting holes) spaced apart in the circumferential direction.

[0014] In this embodiment, the lower connecting tubular portion 122 of the intermediate pile 12 is connected to the upper connecting tubular portion 113 of the lower pile 11, and the lower connecting tubular portion 132 of the upper pile 13 is connected to the upper connecting tubular portion 123 of the intermediate pile 12 (see Figure 11(a)). Between the lower pile 11 and the intermediate pile 12, the lower pile 11 corresponds to the first steel pipe of the present invention, and the intermediate pile 12 corresponds to the second steel pipe of the present invention. Similarly, between the intermediate pile 12 and the upper pile 13, the intermediate pile 12 corresponds to the first steel pipe of the present invention, and the upper pile 13 corresponds to the second steel pipe of the present invention.

[0015] 1(d) and (e) is a member for connecting the connecting tube portions 113, 122 and the connecting tube portions 123, 132. The key member 20 has a key body 21 that is inserted into the upper connecting holes 114, 126 provided in the lower pile 11 and the intermediate pile 12, and the lower connecting holes 124, 134 provided in the intermediate pile 12 and the upper pile 13. The key body 21 includes a key intermediate portion 21a that is located inside each connecting hole 114, 124, 126, 134 when insertion into the connecting hole is complete, a key inner diameter end portion 21b that is located on the inner diameter side of the key intermediate portion 21a, and a key outer diameter end portion 21c that is located on the outer diameter side of the key intermediate portion 21a.

[0016] 1(e) and 2(b), an inner diameter side stopper 22 is supported on the key inner diameter end portion 21b so as to be able to protrude and retract freely. The inner diameter side stopper 22 is in a retracted state that allows radial movement of the key body 21 while the key inner diameter end portion 21b is positioned inside each connecting hole 114, 124, 126, 134. When the key inner diameter end portion 21b moves radially out of each connecting hole 114, 124, 126, 134 and moves into the inner space of the lower connecting cylindrical portion 122, 132 (inner connecting cylindrical portion) (i.e., when insertion of the key body 21 is complete), the inner diameter side stopper 22 protrudes and restricts (blocks) radial movement of the key body 21.

[0017] As shown in Figures 1(d), 2(b), and 2(c), an outer diameter stopper 23 is detachably fixed to the key outer diameter end 21c. The outer diameter stopper 23 is configured, for example, by a male screw that is detachably fixed to a female screw 211d (see Figure 1(d)) provided at the upper end of the key outer diameter end 21c. When in the fixed state, the outer diameter stopper 23 restricts (blocks) movement of the key body 21 in the inward direction, and when in the removed state, it allows movement of the key body 21 in the inward direction.

[0018] According to the joint structure of this embodiment having the above configuration, as shown in FIG. 2(b), for example, by simply pushing the key body 21 from the outside of the upper connecting tube portions 113, 123 toward each connecting hole 114, 124, 126, 134, the connecting tube portions 113, 122 and the connecting tube portions 123, 132 can be connected to each other. Furthermore, as shown in Figure 2(c), if the outer diameter side stopper 23 is removed from the key outer diameter end portion 21c and then the key body 21 is pushed toward the inner space of the lower connecting tube portions 122, 132 (inner connecting tube portions), the key member 20 will come out of each connecting hole 114, 124, 126, 134, and the connecting state between the connecting tube portions 113, 122 and between the connecting tube portions 123, 132 can be released. In this way, by using the joint structure of this embodiment, it is possible to facilitate the work of connecting and unconnecting.

[0019] <Details of steel pipe joint structure> The steel pipe joint structure will be described in detail below.

[0020] <Lower stake 11> The lower pile 11 shown in Figure 1(a) comprises a lower pile main part 111, a tip blade 112, and an upper connecting tubular part 113. The overall length of the lower pile 11 is determined to be a length suitable for transporting the lower pile 11 and for constructing the steel pipe pile 1. The lower pile main portion 111 is made of a circular steel pipe of a predetermined diameter. The diameter of the lower pile main portion 111 is determined appropriately taking into consideration the bearing capacity, construction depth, and ground quality required for the steel pipe pile 1 to be constructed. In this embodiment, the diameter of the lower pile main portion 111 is determined, for example, in the range of 165 mm to 660 mm, but is not limited to this numerical range. Similarly, the thickness of the lower pile main portion 111 is determined, for example, in the range of 6 mm to 12 mm, but is not limited to this numerical range.

[0021] A rotation key 111a protruding radially outward is provided on the outer peripheral surface of the upper end of the lower pile main part 111. The rotation key 111a is a protrusion for transmitting rotation torque from an auger 42 (see, for example, FIG. 8(a)) provided on the pile driver 40 to the lower pile 11. In this embodiment, a total of two rotation keys 111a are provided on each of the front and back surfaces, but three or more rotation keys 111a may be provided, or only one may be provided. In this embodiment, the rotation key 111a is made of a steel member having a substantially rectangular parallelepiped shape, and is fixed by welding or the like to the outer peripheral surface of the upper end of the lower pile main part 111. The rotation key 111a is fitted into a key groove 42d provided in a jig 42c of the auger 42, as shown in Figure 8(a), for example. The rotation key 111a is not limited to being a substantially rectangular parallelepiped steel member, and may have any other shape as long as it can transmit the rotation torque from the auger 42 to the lower pile 11. For example, the rotation key 111a may be formed of a cylindrical steel protrusion.

[0022] As shown in Figure 1(a), the tip blade 112 is configured by fixing two blade members 112a to a plate 112b made of a substantially pentagonal steel plate by welding or the like, and is fixed by welding or the like to the lower end of the lower pile main part 111. The tip blade 112 generates a downward excavation force when rotated in the forward direction, and generates an upward excavation force when rotated in the reverse direction. Therefore, when the lower pile 11, with the tip blade 112 positioned inside the ground G (see Figure 8, etc.), is rotated in the forward direction around its axis, the lower pile 11 excavates downward into the ground G. On the other hand, when the lower pile 11 in the ground G is rotated in the reverse direction around its axis, the lower pile 11 excavates upward into the ground G.

[0023] The upper connecting tube portion 113 is constructed from a circular steel pipe of the same diameter as the lower pile main portion 111, but it may also be constructed from a circular steel pipe of a larger or smaller diameter than the lower pile main portion 111 as long as it is fixed concentrically to the lower pile main portion 111. The upper connecting tube portion 113 is fixed to the upper end of the lower pile main portion 111 by welding or the like, but the fixing means is not limited to welding as long as the upper connecting tube portion 113 can be fixed to the upper end of the lower pile main portion 111 with the required strength. For example, it may be fixed by screwing using bolts, nuts, and fixing rings.

[0024] The upper connecting cylinder portion 113 is provided with a plurality of upper connecting holes 114 spaced apart in the circumferential direction at predetermined axial positions (height positions). In this embodiment, eight upper connecting holes 114 are provided at 45-degree intervals in the circumferential direction, but this configuration is not limiting. For example, four upper connecting holes 114 may be provided at 90-degree intervals in the circumferential direction, or three upper connecting holes 114 may be provided at 120-degree intervals in the circumferential direction. The upper connecting hole 114 includes a substantially circular connecting hole main portion 114a and a downward arc-shaped anti-rotation recess 114b at the lower end of the connecting hole main portion 114a. By configuring the upper connecting hole 114 with the connecting hole main portion 114a and the anti-rotation recess 114b, the upper connecting hole 114 can be drilled, which allows the upper connecting hole 114 to be efficiently formed in the upper connecting cylindrical portion 113.

[0025] The position where the anti-rotation recess 114b is provided is not limited to the lower end of the main connecting hole portion 114a. For example, the anti-rotation recess 114b may be provided at the left end, right end, or upper end of the main connecting hole portion 114a. Furthermore, multiple anti-rotation recesses 114b may be provided.

[0026] <Intermediate Pile 12> The intermediate pile 12 shown in Figure 1 (b) comprises an intermediate pile main part 121, a lower connecting tubular part 122, and an upper connecting tubular part 123. The overall length of the intermediate pile 12 is determined to be a length suitable for transporting the intermediate pile 12 and for constructing the steel pipe pile 1. The intermediate pile main part 121 is made of a circular steel pipe of a predetermined diameter, similar to the lower pile main part 111, and its diameter and thickness are determined similarly to those of the lower pile main part 111. A rotation key 121a protruding radially outward is provided on the outer peripheral surface of the upper end of the intermediate pile main part 121. The rotation key 121a is configured similarly to the rotation key 111a of the upper pile 11.

[0027] The lower connecting tubular portion 122 is made of a circular steel pipe that can be freely inserted into the inner space of the upper connecting tubular portion 113 of the lower pile 11, for example, a circular steel pipe whose outer diameter is one size smaller (for example, within a range of 4 mm to 10 mm) than the inner diameter of the upper connecting tubular portion 113 of the lower pile 11. As a result, the diameter of the lower connecting tubular portion 122 is smaller than the diameter of the intermediate pile main portion 121. Because the diameter of the lower connecting tubular portion 122 is smaller than the diameter of the intermediate pile main portion 121, a disk-shaped fixing plate 125 is interposed between the intermediate pile main portion 121 and the lower connecting tubular portion 122. In this embodiment, the fixing plate 125 is fixed to the lower end of the intermediate pile main portion 121 by welding, and the upper end of the lower connecting tubular portion 122 is fixed to the lower surface of the fixing plate 125 by welding, so that the intermediate pile main portion 121 and the lower connecting tubular portion 122 can be firmly integrated.

[0028] The lower connecting cylinder portion 122 is provided with a plurality of lower connecting holes 124 spaced apart in the circumferential direction at predetermined axial positions. The shape of each lower connecting hole 124 is the same as the shape of each upper connecting hole 114 provided in the upper connecting cylinder portion 123 of the lower pile 11. That is, each lower connecting hole 124 has a connecting hole main portion 124a and a rotation prevention recess 124b. The circumferential spacing between the lower connecting holes 124 is aligned with the circumferential spacing between the upper connecting holes 114 provided in the upper connecting tubular portion 113 of the lower pile 11 .

[0029] The upper connecting tube portion 123 is constructed in the same manner as the upper connecting tube portion 113 of the lower pile 11, and is constructed, for example, from a circular steel pipe of the same diameter as the intermediate pile main portion 121.However, as long as it is fixed concentrically to the intermediate pile main portion 121, it may also be constructed from a circular steel pipe of a larger or smaller diameter than the intermediate pile main portion 121. The upper connecting cylinder portion 123 is provided with a plurality of upper connecting holes 126 spaced apart in the circumferential direction at predetermined axial positions. Each upper connecting hole 126 has the same shape as the upper connecting hole 114 provided in the lower pile 11, and includes a connecting hole main portion 126a and a rotation prevention recess 126b. The circumferential spacing between the upper connecting holes 126 is aligned with the circumferential spacing between the upper connecting holes 114 provided in the lower pile 11, but the circumferential spacing may be determined arbitrarily.

[0030] <Upper stake 13> The upper pile 13 shown in Figure 1(c) has an upper pile main part 131 and a lower connecting tubular part 132. The overall length of the upper pile 13 is determined to be a length suitable for transporting the upper pile 13 and for constructing the steel pipe pile 1. The upper pile main section 131 is made of a circular steel pipe of a predetermined diameter, similar to the lower pile main section 111 and the intermediate pile main section 121, and its diameter and thickness are determined similarly to those of the lower pile main section 111 and the intermediate pile main section 121. A rotation key 131a protruding radially outward is provided on the outer peripheral surface of the upper end of the upper pile main section 131. The rotation key 131a is configured similarly to the rotation keys 111a, 121a of the upper pile 11 and the intermediate pile 12.

[0031] The lower connecting tube portion 132 is constructed in the same manner as the lower connecting tube portion 122 of the intermediate pile 12, and is constructed from a circular steel pipe that can be freely inserted into the inner space of the upper connecting tube portion 123 of the intermediate pile 12, for example, a circular steel pipe whose outer diameter is one size smaller (for example, within the range of 4 mm to 10 mm) than the inner diameter of the upper connecting tube portion 123 of the intermediate pile 12. A disk-shaped fixing plate 135 is interposed between the upper pile main part 131 and the lower connecting tube part 132, similar to the intermediate pile 12, and in this embodiment, the upper pile main part 131 and the lower connecting tube part 132 are firmly integrated by welding. The lower connecting cylinder portion 132 is provided with a plurality of lower connecting holes 134 spaced circumferentially at predetermined axial positions. The shape of each lower connecting hole 134 is the same as the shape of the upper connecting hole 126 of the intermediate pile 12, and each lower connecting hole 134 has a connecting hole main portion 134a and a rotation prevention recess 134b. The circumferential spacing of each lower connecting hole 134 is aligned with the circumferential spacing of the upper connecting holes 126 of the intermediate pile 12.

[0032] <Key member 20> Next, the key member 20 will be described in detail. Figure 3(a) is a front view of the key member 20, Figure 3(b) is a right side view of the key member 20, Figure 3(c) is a rear view of the key member 20, and Figure 3(d) is a plan view of the key member 20. The key member 20 comprises a key body 21 that is inserted into the upper connecting holes 114, 126 provided on the lower pile 11 and the intermediate pile 12, and the lower connecting holes 124, 134 provided on the intermediate pile 12 and the upper pile 13, an inner diameter side stopper 22 supported by the key body 21, and an outer diameter side stopper 23 that is removably attached to the key body 21.

[0033] The key body 21 includes a key main portion 211 made of a cylindrical steel material, and a rotation preventing protrusion 212 protruding from the outer circumferential surface of the key main portion 211 toward the outer periphery. The key main portion 211 is inserted into the connecting hole main portions 114a, 126a, 124a, and 134a of the upper connecting holes 114 and 126 and the lower connecting holes 124 and 134. Therefore, the key main portion 211 is made of a cylindrical steel material with a diameter substantially equal to the diameter of the connecting hole main portions 114a, 126a, 124a, and 134a. The key main portion 211 of this embodiment is provided with a curved, concave fitting groove 211a formed by cutting the lower end of the cylindrical steel material in the front-to-rear direction, and a notch 211b formed by cutting out the upper rear side of the steel material. A female thread 211d is formed on the upper surface of the front end of the key main portion 211 (the upper surface of the key outer diameter end portion 21c), and an outer diameter side stopper 23 (male thread) is detachably fixed to the female thread 211d. The anti-rotation protrusion 212 is composed of a small-diameter cylindrical steel material 212a that is fitted into the fitting groove 211a of the key main part 211. This cylindrical steel material 212a is provided from the front end of the key main part 211 to just before the key inner diameter end part 21b. When the small-diameter cylindrical steel material 212a is fitted into the fitting groove 211a, the lower half of the cylindrical steel material 212a protrudes outward beyond the key main part 211 to form the anti-rotation protrusion 212. When the anti-rotation protrusion 212 is fitted into the anti-rotation recesses 114b, 126b, 124b, and 134b provided in the upper connecting holes 114 and 126 and the lower connecting holes 124 and 134, the key main part 211 is prevented from rotating about its axis. Note that the anti-rotation protrusion 212 is not limited to the length and shape shown in the example, as long as it can prevent the key main part 211 from rotating.

[0034] In the above-described key body 21, the portion where the notch 211b is provided is the key inner diameter end portion 21b, the portion where the outer diameter side stopper 23 is fixed is the key outer diameter end portion 21c, and the portion between the key outer diameter end portion 21c and the key inner diameter end portion 21b is the key intermediate portion 21a. A through hole 211c is formed in the left-right center of the key inner diameter end portion 21b, extending along the axial direction (vertical direction in this example) and into which the shaft portion of the inner diameter side stopper 22 is inserted.

[0035] The inner diameter side stopper 22 includes a shaft portion 22a that is inserted into the through hole 211c of the key inner diameter end portion 21b, and a head portion 22b that is provided at one end (upper end) of the shaft portion 22a and has a shape that does not allow it to be inserted into the through hole 211c. In the illustrated inner diameter side stopper 22, the shaft portion 22a and the head portion 22b are integrally formed from a metal round bar. Specifically, the head portion 22b is provided by bending it at approximately 90 degrees relative to the shaft portion 22a. The overall length of the inner diameter stopper 22 is set to be equal to or shorter than the height of the key body 21, in other words, the height of the upper connecting holes 114, 126 and the lower connecting holes 124, 134. The length of the shank 22a is set to be such that the lower end of the shank 22a is positioned below the lower end of the anti-rotation projection 212 when the head 22b is in contact with the upper surface of the key inner diameter end 21b.

[0036] The illustrated outer diameter side stopper 23 uses a pan head male screw, but other types of male screws may be used as long as the head of the male screw protrudes outward from the outer peripheral surface of the key body 21 when attached to the female screw 211d of the key outer diameter end 21c. Furthermore, a stopper pin consisting of a head and a shaft portion without threads may be used instead of the male screw as outer diameter side stopper 23. When a stopper pin is used as outer diameter side stopper 23, a hole for accommodating the shaft portion may be provided in key outer diameter end portion 21c instead of female screw 211d.

[0037] <Connection and separation work> Next, we will explain the connecting and separating operations using the key member 20. For convenience, we will explain the connecting and separating operations between the upper connecting tube portion 113 of the lower pile 11 and the lower connecting tube portion 122 of the intermediate pile 12, but the connecting and separating operations between the upper connecting tube portion 123 of the intermediate pile 12 and the lower connecting tube portion 132 of the upper pile 13 can also be performed in a similar manner.

[0038] Fig. 4 is a diagram showing a state in which the lower connecting cylindrical portion 122 has been inserted into the inner space of the upper connecting cylindrical portion 113 and the upper connecting hole 114 and the lower connecting hole 124 have been made to communicate with each other, and Fig. 5 is a diagram showing the insertion direction of the key member 20 into the communicating connecting holes 114, 124. Fig. 6(a) is a diagram showing a state in which the key inner diameter end portion 21b has been brought close to the upper connecting hole 114, Fig. 6(b) is a diagram showing a state in which the key inner diameter end portion 21b has been inserted into the upper connecting hole 114, Fig. 6(c) is a diagram showing a state in which the key inner diameter end portion 21b has been moved into the lower connecting hole 124, and Fig. 6(d) is a diagram showing a state in which the key inner diameter end portion 21b has been moved to the inner space of the lower connecting cylindrical portion 122. Figure 7(a) shows the state in which the connecting tube portions 113 and 122 are connected to each other by the key member 20, Figure 7(b) shows the state in which the outer diameter side stopper 23 has been removed from the key body 21, Figure 7(c) shows the state in which the key outer diameter end portion 21c has been moved to the lower connecting hole 124, and Figure 7(d) shows the state in which the key member 20 has been dropped into the inner space of the lower connecting tube portion 122.

[0039] First, the operation of connecting the lower pile 11 (upper connecting tubular portion 113) and the intermediate pile 12 (lower connecting tubular portion 122) will be described. As shown in Figure 4, when connecting the lower pile 11 and the intermediate pile 12, the lower connecting tubular portion 122 of the intermediate pile 12 is inserted into the upper connecting tubular portion 113 of the lower pile 11. Then, the intermediate pile 12 is rotated around its axis to align the circumferential positions of the upper connecting hole 114 of the lower pile 11 and the lower connecting hole 124 of the intermediate pile 12. As described above, the upper connecting holes 114 of the lower pile 11 and the lower connecting holes 124 of the intermediate pile 12 have the same shape and are spaced the same circumferentially. Therefore, as shown in the cross-sectional view of Figure 5, each upper connecting hole 114 and each corresponding lower connecting hole 124 communicate with each other to form a series of spaces into which the key member 20 can be inserted. The key member 20 is inserted from the outside of the lower pile 11 (upper connecting tubular portion 113) in the inward direction, with the key inner diameter end portion 21b facing the upper connecting hole 114 of the lower pile 11.

[0040] 6(a) and 6(b), when inserting the key inner diameter end portion 21b into the upper connecting hole 114 of the lower pile 11, the inner diameter stopper 22 is lifted upward and the lower end of the shaft portion 22a is placed in the upper connecting hole 114 (rotation prevention recess 114b). The inner diameter stopper 22 is housed in the upper connecting hole 114 because its overall length is shorter than the height of the upper connecting hole 114. Therefore, as shown in Figures 6(b) and (c), the key body 21 can move within the upper connecting hole 114 of the lower peg 11 and the lower connecting hole 124 of the intermediate peg 12 along the radial direction of each connecting tube portion 113, 122.

[0041] 6(d), when the key inner diameter end portion 21b reaches the inner space of the lower connecting cylindrical portion 122 of the intermediate pile 12 (i.e., when the insertion of the key body 21 is completed), the inner diameter stopper 22 moves downward (in the axial direction of the shank 22a) due to its own weight until the head portion 22b abuts against the upper surface of the key inner diameter end portion 21b. When the head portion 22b abuts against the upper surface of the key inner diameter end portion 21b, the lower end of the shank 22a of the inner diameter stopper 22 is positioned below the lower edge of the lower connecting hole 124 of the intermediate pile 12. Therefore, even if an attempt is made to move the key member 20 in the outer diameter direction (pulling direction) of each connecting cylindrical portion 113, 122, the shank 22a of the inner diameter stopper 22 abuts against the inner peripheral surface of the lower connecting cylindrical portion 122, restricting the movement. In addition, an outer diameter side stopper 23 is provided on the key outer diameter end portion 21c, and even if an attempt is made to move the key member 20 in the inner diameter direction (insertion direction) of each connecting tube portion 113, 122, the head of the outer diameter side stopper 23 abuts against the outer peripheral surface of the upper connecting tube portion 123, restricting the movement. Therefore, by inserting the key member 20 into the upper connecting hole 114 of the lower pile 11 and the lower connecting hole 124 of the intermediate pile 12, the key member 20 is fixed by the inner diameter side stopper 22 and the outer diameter side stopper 23.

[0042] Next, we will explain how to release the connection between the connecting cylindrical portions 113 and 122. As shown in Figures 7(a) and (b), to release the connection between the connecting cylindrical portions 113 and 122, the outer diameter side stopper 23 is removed from the key body 21. By removing the outer diameter side stopper 23 from the key body 21, the key body 21 can be moved toward the inner diameter side (toward the inner hollow space of the connecting cylindrical portion 122). 7(c) and (d), when the key body 21 is pushed inward, the key member 20 can be dropped into the inner space of the connecting cylindrical portion 122. By dropping each key member 20, the connecting state of each connecting cylindrical portion 113, 122 can be released. In this way, by using the key member 20 of this embodiment, the work of connecting and releasing the connecting tubular portions 113, 122 can be facilitated.

[0043] <Construction of steel pipe pile 1> Next, the construction work of the steel pipe pile 1 will be described. Figure 8(a) is a diagram showing the state in which the lower pile 11 is attached to the pile driver 40 when constructing the steel pipe pile 1, Figure 8(b) is a diagram showing the state in which the lower half of the lower pile 11 is buried in the ground G, Figure 9(a) is a diagram showing the state in which the intermediate pile 12 attached to the pile driver 40 has been moved directly above the lower pile 11, Figure 9(b) is a diagram showing the state in which the lower connecting tube portion 122 of the intermediate pile 12 has been inserted into the upper connecting tube portion 113 of the lower pile 11, Figure 9(c) is a diagram showing the insertion of the key member 20 into each connecting hole 114, 124, Figure 10(a) is a diagram showing the state in which the lower half of the intermediate pile 12 has been buried in the ground G, Figure 10(b) is a diagram showing the state in which the upper pile 13 attached to the pile driver 40 has been moved directly above the intermediate pile 12, and Figure 11(a) is a diagram showing the state in which the steel pipe pile 1 has been buried in the ground G.

[0044] 8(a) and 8(b), the pile driver 40 includes a leader 41 and an auger 42 that is movable along the leader 41. The auger 42 includes an auger body 42a that is movably attached to the leader 41, a rotating part 42b that protrudes downward from the auger body 42a and rotates about its axis, and a jig (cap) 42c that is connected to the lower end of the rotating part 42b and rotates together with the rotating part 42b. The upper connecting tube portion 113 of the lower pile 11 (see Figure 8(a)), the upper connecting tube portion 123 of the intermediate pile 12 (see Figure 9(a)), and the upper pile main portion 131 of the upper pile 13 (see Figure 10(b)) are removably attached to the jig 42c.

[0045] In this embodiment, the jig 42c has a cap shape (a cylindrical shape with a ceiling) with an open bottom end, and a key groove 42d is provided at the bottom end of the jig 42c. The upper connecting tubular portion 113 of the lower pile 11, the upper connecting tubular portion 123 of the intermediate pile 12, and the upper end portion of the upper pile main portion 131 of the upper pile 13 are inserted into the inner space of the jig 42c. The key groove 42d is a generally T-shaped groove that extends from the lower end of the jig 42c toward the upper side. A rotation key 111a of the lower pile main part 11, a rotation key 121a of the intermediate pile main part 12, and a rotation key 131a of the upper pile main part 13 are fitted into the key groove 42d. The rotation torque from the rotating part 42b is transmitted to each of the piles 11, 12, and 13 through the key groove 42d of the jig 42c and each of the rotation keys 111a, 121a, and 131a, causing each of the piles 11, 12, and 13 to rotate about its axis.

[0046] As shown in Figure 8(a), the leader 41 is placed in an upright position, and the upper connecting tube portion 113 of the lower pile 11 is attached to the jig 42c of the auger 42. From this state, the lower pile 11 is rotated in the forward direction around its axis, while the auger 42 is moved downward. When the tip blade 112 of the lower pile 11 comes into contact with the ground G, it excavates downward through the ground G due to the forward rotation. As shown in Figure 8(b), when the upper connecting tube portion 113 of the lower pile 11 has descended to a predetermined height position, the forward rotation of the lower pile 11 by the auger 42 is stopped, and the jig 42c of the auger 42 is removed from the upper connecting tube portion 113 of the lower pile 11.

[0047] As shown in FIG. 9( a ), the upper connecting tubular portion 123 of the intermediate pile 12 is attached to the jig 42 c of the auger 42 , and the lower connecting tubular portion 122 of the intermediate pile 12 is positioned directly above the upper connecting tubular portion 113 of the lower pile 11 . Next, as shown in Figures 9(b) and (c), the auger 42 is moved downward to insert the lower connecting tube portion 122 of the intermediate pile 12 into the inner space of the upper connecting tube portion 113 of the lower pile 11, and the rotating portion 42b of the auger 42 is rotated to align the circumferential positions of the lower connecting hole 124 of the intermediate pile 12 and the upper connecting hole 114 of the lower pile 11, thereby connecting the two connecting holes 114, 124. Next, as shown in Figure 9(c), the key member 20 is inserted into both connecting holes 114, 124. As described above, in this embodiment, eight pairs of the lower connecting holes 124 of the middle pile 12 and the upper connecting holes 114 of the lower pile 11 are provided at intervals in the circumferential direction. The key member 20 is inserted into each of the eight pairs of connecting holes 114, 124. This connects the lower connecting tube portion 122 of the intermediate pile 12 and the upper connecting tube portion 113 of the lower pile 11, and the rotational torque applied to the intermediate pile 12 from the auger 42 is transmitted to the lower pile 11 via the key member 20, causing the intermediate pile 12 and the lower pile 11 to rotate together.

[0048] As shown in Figure 10(a), when the upper connecting tube portion 123 of the intermediate pile 12 has descended to a predetermined height, the forward rotation of the intermediate pile 12 and the lower pile 11 by the rotating portion 42b of the auger 42 is stopped, and the jig 42c of the auger 42 is removed from the upper connecting tube portion 123 of the intermediate pile 12. Next, as shown in Figure 10(b), the upper end portion of the upper pile main portion 131 is attached to the jig 42c of the auger 42, and the lower connecting tube portion 132 of the upper pile 13 is positioned directly above the upper connecting tube portion 123 of the intermediate pile 12. Although not shown in the figures, the subsequent steps for connecting the upper pile 13 and the intermediate pile 12 are the same as those for connecting the intermediate pile 12 and the lower pile 11. Briefly, the lower connecting tube portion 132 of the upper pile 13 is inserted into the inner space of the upper connecting tube portion 123 of the intermediate pile 12, the lower connecting hole 134 of the upper pile 13 is connected to the upper connecting hole 126 of the intermediate pile 12, and the key member 20 is inserted into both connecting holes 134, 126. By this procedure, the upper pile 13 and the intermediate pile 12 are connected.

[0049] As shown in Figure 11(a), when the upper end of the upper pile main part 131 is positioned below the surface of the ground G, the forward rotation of the steel pipe pile 1 (upper pile 13, intermediate pile 12, and lower pile 11) by the auger 42 is stopped, the jig 42c of the auger 42 is removed from the upper pile main part 131, and the pile driving operation by the pile driver 40 is completed.

[0050] <Removal of steel pipe pile 1> Next, the removal work of the steel pipe pile 1 will be described. Figure 12(a) is a diagram showing the state in which the upper pile main part 131 is attached to the pile driver 40 when the steel pipe pile 1 is being removed, and Figure 12(b) is a diagram showing the state in which the upper pile 13, the intermediate pile 12, and the lower pile 11 are rotated in opposite directions to expose the upper half of the intermediate pile 12 above ground. Figure 13(a) is a diagram showing the state in which the key member 20 is dropped into the inner space of the lower connecting tube part 132 of the upper pile 13 when the steel pipe pile 1 is being removed, and Figure 13(b) is a diagram showing the state in which the upper pile 13, separated from the intermediate pile 12, has been pulled up.

[0051] As shown in Figure 12(a), when removing the steel pipe pile 1, the upper end of the upper pile main part 131 is attached to the jig 42c of the auger 42 provided in the pile driver 40, and the rotating part 42b is rotated in reverse. Accordingly, the steel pipe pile 1 (upper pile 13, middle pile 12, and lower pile 11) is rotated in reverse around its axis. The tip blade 112 of the lower pile 11 generates an upward excavation force due to the reverse rotation, so the steel pipe pile 1 rises in the ground G. As shown in Figure 12(b), when the lower connecting tubular portion 122 of the upper pile 13 and the upper connecting tubular portion 123 of the intermediate pile 12 reach a predetermined height above ground, the reverse rotation of the steel pipe pile 1 by the auger 42 is stopped.

[0052] Next, as shown in Figure 13(a), the key member 20 connecting the lower connecting tubular portion 132 of the upper pile 13 and the upper connecting tubular portion 123 of the intermediate pile 12 is removed. The key member 20 can be removed by removing the outer diameter stopper 23 from the key body 21 and then pushing the key body 21 into the inner cavity of the lower connecting tubular portion 132. The key member 20 pushed into the inner cavity is received by the fixing plate 125 interposed between the intermediate pile main body 121 and the lower connecting tubular portion 122, and is held inside the intermediate pile 12. When all the key members 20 are pushed into the inner hollow space of the intermediate pile 12, the connection between the lower connecting tube portion 132 of the upper pile 13 and the upper connecting tube portion 123 of the intermediate pile 12 (the connection between the upper pile 13 and the intermediate pile 12) is released. Therefore, as shown in Figure 13(b), by raising the auger 42 along the leader 41, the upper pile 13 and the intermediate pile 12 can be separated.

[0053] Although not shown in the drawings, the subsequent removal procedure for the steel pipe pile 1 is carried out in the same manner. In brief, after removing the upper pile 13, the jig 42c of the auger 42 is attached to the upper connecting tube portion 123 of the intermediate pile 12, and the rotating portion 42b of the auger 42 is rotated in the reverse direction to raise the lower connecting tube portion 122 of the intermediate pile 12 and the upper connecting tube portion 113 of the lower pile 11 to a predetermined height above ground. After stopping the rotation of the intermediate pile 12 and the lower pile 11, each key member 20 is pushed into the inner cavity of the lower pile 11 (upper connecting tubular portion 113) to release the connection between the intermediate pile 12 and the lower pile 11. After removing the intermediate pile 12, the jig 42c of the auger 42 is attached to the upper connecting tubular portion 113 of the lower pile 11, and the rotating portion 42b of the auger 42 is rotated in the reverse direction to pull the lower pile 11 up from the ground G.

[0054] As can be understood from the above explanation, by using each of the piles 11, 12, 13 and the key member 20 of this embodiment, the connecting cylindrical portions (the set of the upper connecting cylindrical portions 113, 123 and the lower connecting cylindrical portions 122, 132) can be connected together simply by inserting the key member 20 into each of the communicating connecting holes (the upper connecting holes 114, 126 and the lower connecting holes 124, 134), and after removing the outer diameter side stopper 23 from the key outer diameter end portion 21c, the connecting cylindrical portions can be released from their connected state simply by pushing the key member 20 into the inner space of the lower connecting cylindrical portions 122, 132. Therefore, the work of connecting and unconnecting the piles 11, 12, and 13 can be facilitated.

[0055] <Modification> Next, a modified example will be described. (1) In the above-described embodiment, the upper pile 13 includes the upper pile main portion 131 and the lower connecting tubular portion 132, but is not limited to this configuration. Fig. 11(b) shows a steel pipe pile 1' of a first modified example in which a pile head mounting portion 133 is provided on the upper pile 13', buried in the ground, and Fig. 11(c) shows a steel pipe pile 1' of the first modified example in which a pile head member 30 is attached to the pile head mounting portion 133 of the upper pile 13'.

[0056] The pile head mounting portion 133 is made of a circular steel pipe of the same diameter as the upper pile main portion 131, as shown by the dashed line in Figure 1(c), for example, and is fixed to the upper end of the upper pile main portion 131 by welding or the like. The pile head mounting portion 133 may have any shape as long as it can fix the pile head member 30 shown in Figure 11(b). The pile head member 30 shown in Figure 11(c) is a member to which the lower end of a steel pipe column provided in a building is connected, for example. In this embodiment, the lower half of the pile head member 30 is inserted into the inner space of the pile head mounting part 133 and fixed to the pile head mounting part 133 by welding or a set of bolts and nuts.

[0057] (2) In the above-described embodiment, the key body 21 is configured with a cylindrical key main portion 211 and an anti-rotation protrusion 212, thereby preventing the key body 21 from rotating around its axis. However, the present invention is not limited to this configuration. Figure 14(a) is a front view of the key member 20A according to the second modified example, Figure 14(b) is a right side view of the key member 20A according to the second modified example, Figure 14(c) is a rear view of the key member 20A according to the second modified example, Figure 14(d) is a plan view of the key member 20A according to the second modified example, and Figure 14(e) is a diagram showing the upper connecting hole 114A and the lower connecting hole 124A according to the second modified example. In the description of the second modified example, the same components as those in the previously described embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0058] As in the above-described embodiment, the key member 20A shown in Figures 14(a) to 14(d) includes a key body 21A, an inner diameter side stopper 22, and an outer diameter side stopper 23. This key member 20A is characterized in that a flat surface 21d extending along the axial direction is provided on the upper part of the key body 21A. The upper connecting hole 114A of the upper connecting cylinder portion 113 and the lower connecting hole 124A of the lower connecting cylinder portion 122 are shaped to have arc-shaped portions 114c, 124c and linear portions 114d, 124d, the same as those of the key body 21A. In this modification, the flat surface 21d provided on the top of the key body 21 is fitted into the linear portions 114d, 124d of the connecting holes 114A, 124A, thereby preventing the key body 21A from rotating around its axis.

[0059] (3) In the above-described embodiment, the lower connecting tube portions 122, 132 provided at the bottom of the intermediate pile 12 and the upper pile 13 are inserted into the inner spaces of the upper connecting tube portions 113, 123 provided at the top of the lower pile 11 and the intermediate pile 12, but this configuration is not limited to this. FIG. 15 is a view showing upper connecting cylinder portions 113B and 123B and lower connecting cylinder portions 122B and 132B according to the third modified example. As shown in Figure 15, the upper connecting tube portions 113B, 123B provided on the upper part of the lower pile 11 and the intermediate pile 12 may be configured to have a smaller diameter than the lower connecting tube portions 122B, 132B provided on the lower part of the intermediate pile 12 and the upper pile 13, and each upper connecting tube portion 113B, 123B may be inserted into the inner space of each lower connecting tube portion 122B, 132B. 15, a fixing plate 115 is fixed to the upper end of the lower pile main part 111 by welding, and the lower end of the upper connecting cylinder part 113B is fixed to the upper surface of the fixing plate 115 by welding. Similarly, a fixing plate 125 is fixed to the upper end of the intermediate pile main part 121 by welding, and the lower end of the upper connecting cylinder part 123B is fixed to the upper surface of the fixing plate 125 by welding.

[0060] (4) In the above-described embodiment, the inner diameter side stopper 22 is configured to descend by its own weight when the key inner diameter end portion 21b moves into the inner space of the lower connecting tube portion 122, 132 (inner connecting tube portion) (when insertion into each connecting hole 114, 124, 126, 134 is completed), but this configuration is not limited to this. FIG. 16(a) is a horizontal cross-sectional view of a key member 20B according to the fourth modified example, and FIG. 16(b) is a vertical cross-sectional view of the key member 20B according to the fourth modified example. 16(a) and 16(b) differs from the key member 20 described above mainly in the configuration of the inner diameter side stopper 22B. The key member 20B includes a key body 21B inserted into the upper connecting holes 114, 123 and the lower connecting holes 124, 134, an inner diameter side stopper 22B supported by the key body 21B, and an outer diameter side stopper 23 detachably attached to the key body 21B. The key body 21B includes a key main portion 211B made of a cylindrical steel material, and a rotation preventing projection 212B projecting from the outer peripheral surface of the key main portion 211B toward the outer periphery.

[0061] The key main portion 211B is a portion that is inserted into the connecting hole main portions 114a, 124a, 126a, and 134a of the connecting holes 114, 124, 126, and 134. Therefore, the key main portion 211B is made of a cylindrical steel material with approximately the same diameter as the connecting hole main portions 114a, 124a, 126a, and 134a. The key main portion 211B of this embodiment has a curved, concave fitting groove 211a formed by cutting the lower end of a cylindrical steel material in the front-to-rear direction. A female screw 211d is formed on the upper surface of the front end of the key main portion 211B, and an outer diameter side stopper 23 (male screw) is detachably fixed to the female screw 211d. Note that the female screw 211d and the outer diameter side stopper 23 are configured in the same way as in the previously described embodiment, so a description thereof will be omitted.

[0062] The anti-rotation protrusion 212B is made of a small-diameter cylindrical steel material 212a that is fitted over the entire fitting groove 211a of the main part. When the small-diameter cylindrical steel material 212a is fitted into the fitting groove 211a, the lower half of the cylindrical steel material 212a protrudes outward beyond the key main part 211B to form the anti-rotation protrusion 212B. When the anti-rotation protrusion 212B is fitted into the anti-rotation recesses 114b, 124b, 126b, and 134b of the respective connecting holes 114, 124, 126, and 134, the key main part 211B is prevented from rotating about its axis. Note that the anti-rotation protrusion 212B is not limited to the length and shape shown in the example, as long as it can prevent the key main part 211B from rotating.

[0063] A bottomed accommodation recess 21e is provided below the upper end surface of key inner diameter end 21b. Inner diameter side stopper 22B includes locking pin 22c that is accommodated in accommodation recess 21e so as to be able to freely appear and disappear, and spring 22d (e.g., a coil spring) that is accommodated in accommodation recess 21e between locking pin 22c and bottom 21f of accommodation recess 21e and biases (pushes) the tip end portion of locking pin 22c in a direction that causes it to protrude from opening 21g of accommodation recess 21e. In the inner diameter side stopper 22, the locking pin 22c retreats into the accommodating recess 21e to allow radial movement of the key member 20B while the key inner diameter end portion 21b is positioned within each of the connecting holes 114, 124, 126, and 134. When the key inner diameter end portion 21b moves into the inner space of the lower connecting cylindrical portion 122, 132 (inner connecting cylindrical portion), the restoring force of the spring 22d causes the locking pin 22c to protrude from the opening 21g of the accommodating recess 21e, restricting radial movement of the key member 20B.

[0064] As described above, in the key member 20B according to the fourth modification, the restoring force of the spring 22d moves the locking pin 22c along the axial direction and protrudes from the opening 21g of the accommodation recess 21e. In this key member 20B, the locking pin 22c does not move using its own weight but the restoring force of the spring 22d, so that the locking pin 22c can move upward or left or right. The location where the spring 22d is provided is not limited to between the locking pin 22c and the bottom 21f. For example, the spring 22d may be provided midway along the axial direction of the locking pin 22c, and the locking pin 22c and the spring 22d may be integrally formed.

[0065] (5) Figure 16(c) is a cross-sectional view of a key member 20C according to a fifth modified example. The key member 20C shown in Figure 16(c) differs from the key member 20B described above mainly in the configuration of the key body 21C. The key body 21C of the key member 20C is characterized in that it does not have a rotation prevention protrusion and is made of a cylindrical metal member. Like the key member 20B of the fourth modification, the key member 20C of the fifth modification does not use the weight of the locking pin 22c to move, but uses the restoring force of the spring 22d, so the movement direction of the locking pin 22c is not limited to downward. Therefore, it is not necessary to fix the angle of the locking pin 22c by a rotation prevention protrusion, and the configuration can be simplified.

[0066] (6) FIG. 17 is a diagram illustrating the intermediate pile main portion 121′ and the lower connecting tubular portion 122′ of the intermediate pile 12′ according to the sixth modified example, and the upper connecting tubular portion 113 and the key member 20 of the lower pile 11. The intermediate pile 12′ according to the sixth modified example is characterized in that the upper end of the lower connecting tubular portion 122′ is joined to the lower end of the intermediate pile main portion 121′, and no fixing plate 125 is provided. In this configuration, the absence of the fixing plate 125 simplifies the configuration. Since the fixing plate 125 is not provided, when the key member 20 connecting the upper pile 13 and the intermediate pile 12′ is dropped into the steel pipe pile 1, the key member 20 falls into the lower pile 11, but is caught by the tip blade 12. Therefore, the key member 20 can be recovered together with the lower pile 11.

[0067] (7) In the above-described embodiment, the lower pile main portion 111, the intermediate pile main portion 121, and the upper pile main portion 131 are made of circular steel pipes, but are not limited to this configuration. For example, the lower pile main portion 111, the intermediate pile main portion 121, and the upper pile main portion 131 may be made of square steel pipes. Although the steel pipe pile 1 has been exemplified in the above-described embodiment, the present invention can also be applied to a steel pipe column.

[0068] [Summary of embodiments, actions, and effects of the present invention] <First embodiment> The steel pipe joint structure of this embodiment comprises a first steel pipe (such as the lower pile 11) having an outer connecting tubular portion at its end (such as the upper connecting tubular portion 113 of the lower pile 11), a second steel pipe (such as the intermediate pile 12) having an inner connecting tubular portion at its end (such as the lower connecting tubular portion 122 of the intermediate pile 12), and a key member (key member 20, 20A) that connects the two connecting tubular portions with the inner connecting tubular portion inserted into the outer connecting tubular portion. The outer connecting tube portion has multiple outer tube side connecting holes (upper connecting hole 114, etc.), and the inner connecting tube portion has multiple inner tube side connecting holes (lower connecting hole 124, etc.) that can communicate with each outer tube side connecting hole. The key member is provided with a key body (key body 21) which, when completely inserted into each connecting hole in a communicating state, has a key intermediate portion (key intermediate portion 21a) located inside each connecting hole, a key inner diameter end portion (key inner diameter end portion 21b) located on the inner diameter side of the key intermediate portion, and a key outer diameter end portion (key outer diameter end portion 21c) located on the outer diameter side of the key intermediate portion; and inner diameter side stoppers (inner diameter side stoppers 22, 22B) which are supported so as to be able to protrude and retract by the key inner diameter end portions, are in a retracted state allowing radial movement of the key body while the key inner diameter end portions are located in each connecting hole, and protrude when the key inner diameter end portions move radially out of each connecting hole and into the inner void of the inner connecting cylinder portion, thereby restricting the outer diameter movement of the key body 21.

[0069] According to the steel pipe joint structure of this aspect, the connecting cylindrical sections can be connected to each other simply by pushing the key body from the outside of the outer connecting cylindrical section toward each connecting hole, thereby facilitating the work of connecting the connecting cylindrical sections to each other.

[0070] <Second embodiment> In the joint structure for steel pipes according to this embodiment, a through hole (through hole 211c) extending along the axial direction is provided in the key inner diameter end portion (key inner diameter end portion 21b). The inner diameter side stopper includes a shaft portion (shank portion 22a) that is inserted into the through hole, and a head portion (head portion 22b) that is provided at one end of the shaft portion and has a shape that prevents it from being inserted into the through hole. The other end portion of the shaft portion retracts into the through hole while the key inner diameter end portion is positioned in each connecting hole, allowing radial movement of the key body, and protrudes beyond the outer peripheral surface of the key inner diameter end portion to restrict radial movement of the key body when the key inner diameter end portion moves into the inner space of the inner connecting cylindrical portion (lower connecting cylindrical portion 122, etc.). According to the steel pipe joint structure of this aspect, a through hole extending along the axial direction is provided at the inner diameter end of the key, and the inner diameter side stopper has a shaft portion that is inserted into the through hole, and a head portion that is provided at one end of the shaft portion and has a shape that prevents it from being inserted into the through hole, thereby simplifying the configuration of the inner diameter side stopper.

[0071] <Third embodiment> In the joint structure for steel pipes according to this embodiment, a bottomed accommodation recess (accommodation recess 21e) is provided on the outer circumferential surface of the key inner diameter end portion (key inner diameter end portion 21b). The inner diameter side stopper includes a locking pin (locking pin 22c) accommodated in the accommodating recess so as to be able to protrude and retract freely, and a spring (spring 22d) accommodated between the locking pin in the accommodating recess and the bottom (bottom 21f) of the accommodating recess. While the inner diameter end of the key is positioned in each connecting hole (connecting holes 114, 124, etc.), the locking pin retracts into the accommodating recess to allow radial movement of the key body (key body 21B). When the inner diameter end of the key moves into the inner hollow space of the inner connecting cylindrical part, the locking pin protrudes from the opening (opening 21g) of the accommodating recess due to the restoring force of the spring, restricting radial movement of the key body. According to the steel pipe joint structure of this aspect, the locking pin is moved by the restoring force of the spring, so the movement direction of the locking pin can be set to upward or left / right.

[0072] <Fourth embodiment> The steel pipe joint structure according to this embodiment is provided with an outer diameter side stopper (outer diameter side stopper 23) that is removably fixed to the key outer diameter end portion (key outer diameter end portion 21c) and that restricts movement of the key body in the inner diameter direction when fixed and allows movement of the key body (key body 21, 21B) in the inner diameter direction when removed. According to the steel pipe joint structure of this embodiment, the connection between the connecting cylindrical portions can be released simply by removing the outer diameter side stopper from the outer diameter end of the key and then pushing the key body toward the inner space of the inner connecting cylindrical portion.

[0073] <Fifth embodiment> In the steel pipe joint structure of this embodiment, a female thread (female thread 211d) is provided on the outer surface of the key outer diameter end portion (key outer diameter end portion 21c), and the outer diameter side stopper (outer diameter side stopper 23) is composed of a male thread that is detachably fixed to the female thread. According to the steel pipe joint structure of this aspect, a female thread is provided on the outer peripheral surface of the outer diameter end of the key, and the outer diameter side stopper is formed by a male thread, so the structure can be simplified. <Sixth embodiment> The steel pipe pile 1 according to this embodiment is constructed by a plurality of steel pipes (lower pile 11, intermediate pile 12, upper pile 13) each having the joint structure according to any one of the above-described embodiments. According to the steel pipe pile 1 of this embodiment, the construction work of the steel pipe pile 1 can be facilitated. [Explanation of symbols]

[0074] 1, 1'...steel pipe pile, 11...lower pile, 111...lower pile main part, 111a...rotation key, 12...tip blade, 112a...blade member, 112b...plate, 113, 113B...upper connecting tube part, 114, 114A...upper connecting hole, 114a...connecting hole main part, 114b...rotation stop recess, 114c...arc-shaped part, 114d...straight part, 12...intermediate pile, 121, 121'...intermediate pile main part, 121a...rotation key, 122, 122', 122 B...lower connecting tube portion, 123, 123B...upper connecting tube portion, 124, 124A...lower connecting hole, 124a...connecting hole main portion, 124b...rotation prevention recess, 124c...arc-shaped portion, 124d...straight portion, 125...fixing plate, 126...upper connecting hole, 126a...connecting hole main portion, 126b...rotation prevention recess, 13, 13'...upper pile, 131...upper pile main portion, 131a...rotation key, 132, 132B...lower connecting tube portion, 133...pile head mounting portion, 134...lower connecting hole, 134a...connecting hole main portion, 134b...rotation prevention recess, 135...fixing plate, 20, 20A, 20B, 20C...key member, 21, 21A, 21B, 21C...key body, 21a...key intermediate portion, 21b...key inner diameter end portion, 21c...key outer diameter end portion, 21d...flat surface, 21e...accommodating recess, 21f...accommodating recess bottom portion, 21g...accommodating recess opening portion, 211, 211B...key main portion, 211a...fitting groove , 211b...notch, 211c...through hole, 211d...female screw, 212, 212B...rotation prevention protrusion, 212a...cylindrical steel material, 22...inner diameter side stopper, 22a...shaft portion, 22b...head portion, 22c...locking pin, 22d...spring, 23...outer diameter side stopper, 30...pile head member, 40...pile driver, 41...leader, 42...auger, 42a...auger body, 42b...rotating portion, 42c...jig (cap), 42d...key groove, G...ground

Claims

1. A steel pipe joint structure comprising a first steel pipe having an outer tubular connecting portion at an end thereof, a second steel pipe having an inner tubular connecting portion at an end thereof, and a key member that connects the two tubular connecting portions together with the inner tubular connecting portion inserted into the outer tubular connecting portion, the outer connecting cylinder portion has a plurality of outer cylinder side connecting holes, the inner connecting cylinder portion has a plurality of inner cylinder side connecting holes that can communicate with the outer cylinder side connecting holes, The key member is a key body including a key intermediate portion located inside each of the connecting holes when the key body is completely inserted into each of the connecting holes in a communicating state, a key inner diameter end portion located on the inner diameter side of the key intermediate portion, and a key outer diameter end portion located on the outer diameter side of the key intermediate portion; and an inner diameter side stopper that is supported by the key inner diameter end so as to be able to protrude and retract freely, that is in a retracted state allowing radial movement of the key body while the key inner diameter end is positioned within each of the connecting holes, and that protrudes when the key inner diameter end moves radially out of each of the connecting holes and into an inner void of the inner connecting cylindrical part, thereby restricting movement of the key body in the outer diameter direction.

2. The key inner diameter end portion is provided with a through hole extending along the axial direction, the inner diameter side stopper includes a shaft portion that is inserted into the through hole, and a head portion that is provided at one end of the shaft portion and has a shape that prevents it from being inserted into the through hole, 2. The steel pipe joint structure according to claim 1, wherein the other end of the shank retracts into the through hole while the key inner diameter end is positioned within each of the connecting holes to allow radial movement of the key member, and when the key inner diameter end moves to the inner void of the inner connecting cylindrical portion, protrudes beyond the outer peripheral surface of the key inner diameter end toward the other end, restricting movement of the key body in the outer diameter direction.

3. a bottomed receiving recess is provided on the outer peripheral surface of the inner diameter end of the key; the inner diameter side stopper includes a locking pin accommodated in the accommodation recess so as to be able to freely protrude and retract, and a spring that biases the locking pin in a direction that causes the locking pin to protrude from an opening of the accommodation recess, 2. The steel pipe joint structure according to claim 1, wherein the locking pin retracts into the accommodating recess while the key inner diameter end is positioned within each connecting hole, allowing radial movement of the key member, and when the key inner diameter end moves to the inner hollow space of the inner connecting cylindrical portion, the locking pin protrudes from the opening of the accommodating recess by the spring, restricting movement of the key body in the outer diameter direction.

4. 2. The steel pipe joint structure according to claim 1, further comprising an outer diameter side stopper that is removably fixed to the outer diameter end of the key, restricts movement of the key body in the inner diameter direction when fixed, and allows movement of the key body in the inner diameter direction when removed.

5. A female screw is provided on the outer peripheral surface of the outer diameter end of the key, 5. A joint structure for a steel pipe pile according to claim 4, wherein the outer diameter side stopper is constituted by a male screw that is detachably fixed to the female screw.

6. The key body includes a main portion made of a cylindrical steel material and a rotation prevention protrusion protruding outward from an outer peripheral surface of the main portion, The steel pipe joint structure according to claim 1, characterized in that each of the connecting holes comprises a connecting hole main portion into which the main portion is inserted, and a rotation prevention recess into which the rotation prevention protrusion is inserted.

7. A steel pipe pile constructed from a plurality of steel pipes each having the steel pipe joint structure according to any one of claims 1 to 6.

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