JP6354911B2 - Steel pipe pile joint structure - Google Patents

Description

The present invention relates to a joint structure for steel pipe piles.
This application claims priority based on Japanese Patent Application No. 2015-231400 for which it applied to Japan on November 27, 2015, and uses the content here.

Conventionally, a non-welded mechanical joint has been required in order to realize easy construction in a confined area and shortening the work period. For example, joint structures disclosed in Patent Documents 1 and 2 have been proposed for the purpose of connecting a plurality of steel pipe piles in the axial direction with mechanical joints.

In the joint structure of steel pipe piles disclosed in Patent Document 1, a pair of externally fitted end portions and internally fitted end portions that can be fitted to each other are separately provided on the first pile and the second pile adjacent to each other in the axial direction. It is formed. In this joint structure, an engaging portion and an engaged portion that are engaged with each other by relative rotation around the shaft core are formed in a state where the outer fitting end portion and the inner fitting end portion are fitted. In the joint structure of the steel pipe pile disclosed in Patent Document 1, the separation preventing means for preventing the engaged engagement portion and the engaged portion from separating in the radial direction of the first pile or the second pile. , Provided at the engaging portion and the engaged portion.

In the joint structure of steel pipe piles disclosed in Patent Document 2, a pair of external fitting end portions and internal fitting end portions that can be fitted to each other are separately provided in the first pile and the second pile adjacent in the axial direction. It is formed. In this joint structure, with the outer fitting end portion and the inner fitting end portion fitted together, the engaging convex portion and the engaged convex portion that are engaged with each other by relative rotation around the axial center are in the axial direction. A plurality are formed. In the joint structure of the steel pipe pile disclosed in Patent Document 2, the formation portion of the engagement convex portion provided on the distal end side of the outer fitting end portion is more than the formation portion of the engagement convex portion provided on the base end side. Formed in large diameter. In addition, the portion where the inner protrusion end portion is provided on the distal end side is formed to have a smaller diameter than the portion where the engagement convex portion is provided on the base end side.

Japanese Unexamined Patent Publication No. 11-43937 Japanese Unexamined Patent Publication No. 11-43936

Here, the joint structure of a steel pipe pile is a state in which a plurality of steel pipe piles are coupled in the axial direction, and compression, tension, and bending forces act on the joint portion. The joint structure of a steel pipe pile disclosed in Patent Document 1 is not limited to the outer fitting end part and the inner fitting end part from the base end side to the tip end side, although the load ratios of compression, tension, and bending force are different. The plate thicknesses of the engaging portions are all the same in the axial direction. For this reason, in the joint structure of the steel pipe pile disclosed in Patent Document 1, in particular, because there are many useless parts in the thickness of the outer fitting end portion and the distal end side of the inner fitting end portion, the plate thickness increases more than necessary. As a result, there was a problem that the cost increased.

On the other hand, in the joint structure of the steel pipe pile disclosed in Patent Document 2, the plate thickness of the engaged convex portion is gradually reduced from the proximal end side to the distal end side of the outer fitting end portion and the inner fitting end portion. By doing so, the load ratio of the force of compression, tension and bending is taken into consideration. However, in the steel pipe pile joint structure disclosed in Patent Document 2, since the plate thickness of the engaged protrusions is the same between the outer fitting end part and the inner fitting end part, the steel material weight of the entire joint is more than necessary. There was a problem that the cost increased due to the increase.

And the joint structure of the steel pipe pile disclosed by patent document 2 is by making the plate | board thickness of a to-be-engaged convex part gradually small toward the front end side from the base end side of an external fitting end part and an internal fitting end part. The taper is formed in the axial direction. However, in the joint structure of steel pipe piles disclosed in Patent Document 2, the ratio between the protruding height of the compression surface and the protruding height of the tensile surface is less than 0.50. For this reason, the steel material weight of the whole joint for ensuring equal strength of compression, tension, and bending cannot be minimized, resulting in an increase in material cost.

This invention is made | formed in view of said situation, and it aims at provision of the joint structure of the steel pipe pile which the workability improved by weight reduction.

(1) In the joint structure of a steel pipe pile according to one aspect of the present invention, the first steel pipe pile having an outer fitting end part and the second steel pipe pile having an inner fitting end part are formed by the outer fitting end part and the inner fitting. It is a joint structure of steel pipe piles connected in the state of sharing the same axial core line with the end part, and when viewed in cross section along the axial core line: on the axial core line inside the external fitting end part An outer fitting step portion is provided at a plurality of positions along the outer steel plate so that the diameter gradually increases toward the second steel pipe pile, and each of the outer fitting step portions is relatively close to the second steel pipe pile. A fitting mountain portion and an outer fitting valley portion adjacent to the outer fitting mountain portion; a step toward the first steel pipe pile at a plurality of positions along the axial core line outside the inner fitting end portion. The inner fitting step portion is provided so as to reduce the diameter of the inner fitting step, and each of the inner fitting step portions is relatively close to the first steel pipe pile, and the inner fitting step portion is adjacent to the inner fitting step portion. Each of the inner fitting mountain portions in a state in which each of the inner fitting mountain portions is inserted into the outer fitting end portion and relatively rotated around the axis line. In each of the outer fitting mountain portions, the outer fitting mountain adjacent to the outer fitting mountain portion due to the protruding height of the outer fitting mountain portion relatively close to the second steel pipe pile. The ratio obtained by dividing the protrusion height of the portion is 0.5 or more and 0.9 or less, and in each of the internal fitting mountain portions, the protruding height of the internal fitting mountain portion that is relatively close to the first steel pipe pile Then, the ratio obtained by dividing the protruding height of the internal fitting mountain portion adjacent to the internal fitting mountain portion is 0.5 or more and 0.9 or less, and the internal fitting closest to the first steel pipe pile. The plate thickness of the external fitting valley portion closest to the second steel pipe pile is smaller than the plate thickness of the valley portion, and depending on the plate thickness of the internal fitting valley portion closest to the first steel pipe pile. The ratio obtained by dividing the thickness of the valley fitting nearest the outside of the second steel pipe pile, is 0.84 or more; and wherein the.

According to the joint structure of a steel pipe pile having the above configuration, the weight of the joint of the steel pipe pile can be reduced, and workability is improved.

(2) In the joint structure of steel pipe piles according to (1) above, the plate of the outer fitting valley portion closest to the second steel pipe pile is determined by the plate thickness of the inner fitting valley portion closest to the first steel pipe pile. The ratio obtained by dividing the thickness may be 0.84 or more and 0.94 or less.

In this case, the weight of the steel pipe pile joint can be further reduced.

(3) In the steel pipe pile joint structure according to (1) or (2) above, in each of the external fitting mountain portions, the protrusion height of the external fitting mountain portion that is relatively close to the second steel pipe pile. The ratio obtained by dividing the protruding height of the outer fitting mountain portion adjacent to the outer fitting mountain portion is 0.6 or more and 0.8 or less, and in each of the inner fitting mountain portions, the relative The ratio obtained by dividing the projecting height of the inner fitting mountain portion adjacent to the inner fitting mountain portion by the projecting height of the inner fitting mountain portion close to the first steel pipe pile is 0.6 or more and 0.8 or less. It may be.

In this case, the weight of the steel pipe pile joint can be reduced while maintaining the strength of the steel pipe pile joint.

According to the joint structure of a steel pipe pile according to the above aspect of the present invention, workability is improved by reducing the joint weight.

It is a perspective view which shows the joint structure of the steel pipe pile which concerns on 1st Embodiment of this invention. It is a figure which shows the external fitting end part of the joint structure of the steel pipe pile, Comprising: It is sectional drawing at the time of seeing in the cross section containing an axial core wire. It is a figure which shows the external fitting end part of the joint structure of the same steel pipe pile, Comprising: It is a fragmentary sectional view of the A section of FIG. It is a side view which shows the internal fitting end part of the joint structure of the steel pipe pile. It is a figure which shows the internal fitting end part of the joint structure of the steel pipe pile, Comprising: It is a fragmentary sectional view of the B section of FIG. It is a perspective view which shows the internal fitting end part inserted in an external fitting end part by the joint structure of the same steel pipe pile. In the joint structure of the steel pipe pile, it is a perspective view which shows the state which rotated the inner fitting end part with respect to the outer fitting end part, and a part of outer fitting end part is seen by the cross section. It is a fragmentary sectional view of the C section of Drawing 7, and is a figure showing the tensile force which acts on the tension surface of the joint structure of the steel pipe pile. It is a fragmentary sectional view of the C section of Drawing 7, and is a figure showing compressive force which acts on the compression surface of the joint structure of the steel pipe pile. It is a fragmentary sectional view which shows the plate | board thickness of each external fitting step part and an internal fitting step part by the joint structure of the same steel pipe pile. It is a figure which shows the joint structure of the conventional steel pipe pile, Comprising: It is a fragmentary sectional view which shows the plate | board thickness of an external fitting step part and an internal fitting step part. It is a fragmentary sectional view showing the modification of an external fitting surplus length part and an internal fitting surplus length part by the joint structure of the steel pipe pile. It is the fragmentary sectional view which shows the joint structure of a steel pipe pile, Comprising: (a) shows the plate | board thickness of the external fitting step part and internal fitting step part of the joint structure which concerns on the said embodiment, (b) is the conventional joint. The plate thickness of the external fitting step part and internal fitting step part of a structure is shown, (c) shows the comparison of the plate thickness in (a) and (b). The graph which shows the relationship between the diameter-thickness ratio of the outer diameter of a steel pipe pile, and the thickness of an external fitting end part, and the ratio of the maximum bending moment and the total plastic bending moment of a steel pipe pile of the joint structure of the steel pipe pile concerning the said embodiment It is. It is a graph which shows the relationship between the diameter thickness ratio and proof stress ratio of the internal fitting end part in the joint structure of the steel pipe pile which concerns on the said embodiment, and is a graph which shows the relationship between the diametrical thickness ratio and proof stress ratio of an internal fitting end part. . It is a graph which shows the relationship between the diameter thickness ratio and proof stress ratio of the inner fitting end part in the joint structure of the steel pipe pile which concerns on the said embodiment, and is a graph which shows the relationship between the diametrical thickness ratio and proof stress ratio of an external fitting end part. . It is a graph which shows the relationship between the ratio of the protrusion height of a compression surface in the joint structure of the steel pipe pile, and the protrusion height of a tension surface, and the joint thickness ratio from which the tensile strength and compression strength equivalent to a steel pipe pile are obtained. It is a fragmentary sectional view for demonstrating the relationship of the protrusion height which considered the clearance in the joint structure of the steel pipe pile. It is a graph which shows the bending test result which changed the protrusion height of the tension surface in the joint structure of the steel pipe pile. It is a graph which shows the relationship between a diameter thickness ratio and plate | board thickness ratio about the joint structure of the steel pipe pile which concerns on 2nd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments.

<First Embodiment>
The steel pipe pile joint structure 7 according to the present embodiment is used for a landslide pile, a support pile, a friction pile or the like, and as shown in FIG. Two steel pipe piles 2 are connected in the axial direction Y.

The steel pipe pile joint structure 7 includes an outer fitting end portion 3 and an inner fitting end portion 5 that can be fitted to each other. The outer fitting end 3 is attached to the end of the first steel pipe pile 1 by welding or the like, and the inner fitting end 5 is attached to the end of the second steel pipe pile 2 by welding or the like. In a state where the outer fitting end 3 and the inner fitting end 5 share the same axis L, the outer fitting end 3 and the inner fitting end 5 are mutually in an axial direction Y parallel to the axis L. It becomes a pair of opposites.

In the steel pipe pile joint structure 7, the outer fitting groove portion 32 is mainly formed inside the outer fitting end portion 3, and the inner fitting groove portion 52 is formed outside the inner fitting end portion 5. The steel pipe pile joint structure 7 is applied to a gear-type joint in which a plurality of outer fitting mountain parts 31 and a plurality of inner fitting mountain parts 51 are formed on substantially the same circumference in the circumferential direction W. Here, each of the first steel pipe pile 1 and the second steel pipe pile 2 has, for example, an outer diameter Dp of the steel pipe pile of about 318.5 mm to 1625.6 mm, and a plate thickness t of the steel pipe pile of 6.0 mm to 30.0 mm. Targeting the degree.

The outer fitting end portion 3 is formed with a plurality of outer fitting mountain portions 31 formed so as to protrude inward in the axis orthogonal direction X and a plurality of outer fitting mountain portions 31 formed adjacent to the outer fitting mountain portion 31 in the circumferential direction W. It has the external fitting groove part 32 and the external fitting trough part 33 formed in the base end side B from the external fitting mountain part 31 in the axial direction Y. The external fitting end portion 3 is formed by the external fitting mountain portions 31 and the external fitting valley portions 33 being alternately adjacent to each other in the axial direction Y.

In the outer fitting end portion 3, the outer fitting mountain portions 31 and the outer fitting groove portions 32 are alternately formed in the circumferential direction W, and the plurality of outer fitting mountain portions 31 are substantially aligned in the axial direction Y and the circumferential direction W. While being arranged, the plurality of external fitting groove portions 32 are arranged in a substantially line in the axial direction Y and the circumferential direction W. The external fitting end part 3 has an external fitting extra length part 38 as a part attached to the end part of the first steel pipe pile 1 by welding or the like.

The inner fitting end 5 has a plurality of inner fitting mountain parts 51 formed to protrude outward in the axial center orthogonal direction X and a plurality of inner fitting mountain parts 51 formed adjacent to the inner fitting mountain part 51 in the circumferential direction W. It has the internal fitting groove part 52 and the internal fitting trough part 53 formed in the base end side B from the internal fitting mountain part 51 in the axial direction Y. The internal fitting end portion 5 is formed such that internal fitting mountain portions 51 and internal fitting valley portions 53 are alternately adjacent to each other in the axial direction Y.

In the inner fitting end portion 5, the inner fitting mountain portions 51 and the inner fitting groove portions 52 are alternately formed in the circumferential direction W, and the plurality of inner fitting mountain portions 51 are substantially aligned in the axial direction Y and the circumferential direction W. In addition to the arrangement, the plurality of internally fitted groove portions 52 are arranged in a substantially line in the axial direction Y and the circumferential direction W. The internal fitting end portion 5 has an internal fitting extra length portion 58 as a portion attached to the end portion of the second steel pipe pile 2 by welding or the like.

As shown in FIG. 2, the outer fitting mountain portion 31 has an axis of the first steel pipe pile 1 that is more than the outer fitting structural portion 32 adjacent in the circumferential direction W and the outer fitting valley portion 33 adjacent in the axial direction Y. It is formed to project in a substantially rectangular shape or the like toward the central axis in the core direction Y. At this time, as shown in FIG. 3, the outer fitting mountain portion 31 has a predetermined protruding height in the axial center orthogonal direction X from the outer fitting valley portion 33 adjacent to the distal end side A or the proximal end side B in the axial direction Y. And Hc and Ht.

The external fitting valley portion 33 is provided with a plurality of external fitting step portions 4 from the distal end side A to the proximal end side B in the axial direction Y. In each of the external fitting step portions 4, the axial center orthogonal direction X is provided. And having a predetermined plate thickness. The outer fitting valley portion 33 has an outer fitting step portion 4 on the most proximal side B in the axial direction Y to an outer fitting extra length portion 38 having a predetermined plate thickness D in the axial direction orthogonal to the axial direction Y. Are formed next to each other.

In the outer fitting valley portion 33, the outer fitting step portion 4 closest to the distal end side A in the axial direction Y is the first outer fitting step portion 41. For example, when the external fitting stepped portion 4 is provided over four steps in the axial direction Y, the external fitting valley portion 33 is first outer in order from the distal end side A to the proximal end side B in the axial direction Y. A fitting step 41, a second outer fitting step 42, a third outer fitting step 43, and a fourth outer fitting step 44 are provided.

That is, the outer fitting end 3 has a step toward the second steel pipe pile 2 at a plurality of positions along the axis core L inside the outer fitting end 3 when viewed in a cross section including the axis L. The external fitting step part 4 is provided so that it may expand in diameter. Each outer fitting step part 4 has an outer fitting mountain part 31 relatively close to the second steel pipe pile 2 and an outer fitting valley part 33 adjacent to the outer fitting mountain part 31.
Note that hatching is omitted in the cross-sectional views of FIGS. 3, 5, 8 to 13, and 16 for easy understanding of the drawings.

As shown in FIG. 4, the inner fitting mountain portion 51 has an axial core of the second steel pipe pile 2 than the inner fitting groove portion 52 adjacent in the circumferential direction W and the inner fitting valley portion 53 adjacent in the axial direction Y. It is formed to project in a substantially rectangular shape or the like toward the opposite side of the central axis in the direction Y. At this time, as shown in FIG. 5, the internal fitting mountain portion 51 has a predetermined protruding height in the axial center orthogonal direction X from the internal fitting valley portion 53 adjacent to the distal end side A or the proximal end side B in the axial direction Y. And Hc and Ht.

The internal fitting valley portion 53 is provided with a plurality of internal fitting step portions 6 from the distal end side A to the proximal end side B in the axial direction Y. In each internal fitting step portion 6, the axial center orthogonal direction X is provided. And having a predetermined plate thickness. The inner fitting valley portion 53 has an inner fitting step portion 6 on the most proximal side B in the axial direction Y to an inner fitting extra length portion 58 having a predetermined plate thickness D in the axial direction orthogonal to the axial direction Y. Are formed next to each other. The plate thickness D of the internal fitting surplus length portion 58 does not necessarily need to match the plate thickness D of the external fitting surplus length portion 38.

In the internal fitting valley portion 53, the internal fitting step portion 6 closest to the tip end side A in the axial direction Y is the first internal fitting step portion 61. For example, when the internal fitting stepped portion 6 is provided in four steps in the axial direction Y, the internal fitting valley portion 53 is first in order from the distal end side A to the proximal end side B in the axial direction Y. A fitting step 61, a second fitting step 62, a third fitting step 63, and a fourth generic step 64 are provided.

That is, the inner fitting end portion 5 has a step toward the first steel pipe pile 1 at a plurality of positions along the axial core line L outside the inner fitting end portion 5 when viewed in cross section along the axial core line L. The internal fitting step 6 is provided so as to reduce the diameter. Each internal fitting step part 6 has an internal fitting mountain part 51 relatively close to the first steel pipe pile 1 and an internal fitting valley part 53 adjacent to the internal fitting mountain part 51.

As shown in FIG. 6 and FIG. 7, the joint structure 7 of the steel pipe pile includes the first steel pipe pile 1 and the second steel pipe pile 2 by fitting the outer fitting end portion 3 and the inner fitting end portion 5 to each other. Are connected in the axial direction Y.

As shown in FIG. 6, the steel pipe pile joint structure 7 is first inserted into the outer fitting end 3 attached to the first steel pipe pile 1 with the inner fitting end 5 attached to the second steel pipe pile 2. To do. At this time, as for the joint structure 7 of a steel pipe pile, the protrusion height of the external fitting mountain part 31 and the internal fitting mountain part 51 shall be below the depth of the axial center orthogonal direction X of the internal fitting groove part 52 and the external fitting groove part 32. Thus, the outer fitting mountain portion 31 and the inner fitting mountain portion 51 pass through the inner fitting groove portion 52 and the outer fitting structure portion 32.

Next, as shown in FIG. 7, the joint structure 7 of the steel pipe pile is formed by connecting the first steel pipe pile 1 and the second steel pipe pile 2 with the inner fitting end portion 5 into the outer fitting end portion 3. Rotate relative to the circumferential direction W around L. At this time, as for the joint structure 7 of a steel pipe pile, the protrusion height of the external fitting peak part 31 and the internal fitting peak part 51 is below the depth of the axial center orthogonal direction X of the internal fitting valley part 53 and the external fitting valley part 33. Thus, the outer fitting mountain portion 31 and the inner fitting mountain portion 51 are fitted into the inner fitting valley portion 53 and the outer fitting valley portion 33.

In the steel pipe pile joint structure 7, the length in the axial direction Y of the external fitting mountain portion 31 is set to be equal to or less than the length in the axial direction Y of the internal fitting valley portion 53, and the axial direction of the internal fitting mountain portion 51. The length of Y is equal to or less than the length of the external fitting valley portion 33 in the axial direction Y. At this time, in the joint structure 7 of the steel pipe pile, the outer fitting mountain portion 31 and the inner fitting mountain portion 51 are in a state where the inner fitting end portion 5 inserted into the outer fitting end portion 3 is relatively rotated in the circumferential direction W. They are locked together in the axial direction Y. In addition, about the external fitting end part 3 or the internal fitting end part 5, the number of the external fitting mountain parts 31 or the internal fitting mountain parts 51 in the circumferential direction W is preferably 4, 16, 32, or the like.

As shown in FIG. 8, the joint structure 7 of the steel pipe pile is formed by pivoting the first steel pipe pile 1 and the second steel pipe pile 2 in a state where the outer fitting mountain portion 31 and the inner fitting mountain portion 51 are locked to each other. A tensile force Pt acts in the direction of separating from each other in the core direction Y. At this time, the outer fitting mountain portion 31 is a tensile surface 31 a that is the base end side B in the axial direction Y, and the tensile force Pt is transmitted from the inner fitting mountain portion 51. At the same time, the inner fitting mountain portion 51 is a tensile surface 51 a that is the base end side B in the axial direction Y, and the tensile force Pt is transmitted from the tensile surface 31 a of the outer fitting mountain portion 31.

In the joint structure 7 of the steel pipe pile, the tensile surface 31a of the outer fitting mountain portion 31 and the tensile surface 51a of the inner fitting mountain portion 51 have a predetermined protruding height Ht in the axial direction orthogonal to the axis X. Further, the tensile force Pt having the same magnitude is transmitted between the tension surface 31 a of the outer fitting mountain portion 31 and the tension surface 51 a of the inner fitting mountain portion 51. At this time, in each of the outer fitting stepped portion 4 and the inner fitting stepped portion 6, it is transmitted from the distal end side A in the axial direction Y toward the proximal end side B to each of the outer fitting mountain portion 31 and the inner fitting mountain portion 51. The load factor of the applied tensile force Pt gradually increases. As a result, the load factor of the tensile force pt at the fourth outer fitting step portion 44 and the fourth inner fitting step portion 64 that are the most proximal side B is maximized.

Moreover, as shown in FIG. 9, the joint structure 7 of a steel pipe pile has the 1st steel pipe pile 1 and the 2nd steel pipe pile 2 in the state to which the external fitting mountain part 31 and the internal fitting mountain part 51 were mutually latched. The compressive force Pc acts in a direction that causes the two to approach each other in the axial direction Y. At this time, the outer fitting mountain portion 31 is a compression surface 31 b that is the tip end side A in the axial direction Y, and the compression force Pc is transmitted from the inner fitting mountain portion 51. At the same time, the internal fitting mountain portion 51 is a compression surface 51 b that is the tip side A in the axial direction Y, and the compression force Pc is transmitted from the compression surface 31 b of the external fitting mountain portion 31.

In the steel pipe pile joint structure 7, the compression surface 31 b of the outer fitting mountain portion 31 and the compression surface 51 b of the inner fitting mountain portion 51 have a predetermined protruding height Hc in the axial center orthogonal direction X. Further, the compression force Pc having the same magnitude is transmitted between the compression surface 31 b of the outer fitting mountain portion 31 and the compression surface 51 b of the inner fitting mountain portion 51. At this time, in each of the outer fitting stepped portion 4 and the inner fitting stepped portion 6, it is transmitted from the distal end side A in the axial direction Y toward the proximal end side B to each of the outer fitting mountain portion 31 and the inner fitting mountain portion 51. The burden rate of the compression force Pc to be applied gradually increases. As a result, the load factor of the compressive force Pc at the fourth outer fitting step portion 44 and the fourth inner fitting step portion 64 that are the most proximal side B is maximized.

As shown in FIG. 10, the joint structure 7 of the steel pipe pile according to the present embodiment includes an outer fitting valley portion 33 and an inner fitting valley portion 53, each having an outer fitting step portion 4 and an inner fitting step portion 6. It is formed to have a predetermined plate thickness in the orthogonal direction X.

In the external fitting valley portion 33, the external fitting valley portion 33 in the first external fitting step portion 41 has a plate thickness tb1, the external fitting valley portion 33 in the second external fitting step portion 42 has a plate thickness tb2, and a third external fitting step. The outer fitting valley portion 33 in the portion 43 has a plate thickness tb3, and the outer fitting valley portion 33 in the fourth outer fitting step portion 44 has a plate thickness tb4. The outer fitting valley portion 33 is, in particular, the outer fitting step portion 4 adjacent in the axial direction Y, and the thickness of the outer fitting valley portion 33 in the outer fitting step portion 4 on the base end side B in the axial direction Y is In the axial direction Y, the thickness is larger than the thickness of the outer fitting valley portion 33 at the outer fitting step portion 4 on the distal end side A.

At this time, when the outer fitting stepped portion 4 is provided over four steps from the distal end side A to the proximal end side B in the axial direction Y, the outer fitting valley portion 33 is a plate at the second outer fitting stepped portion 42. The thickness tb2 is larger than the plate thickness tb1 at the first external fitting step portion 41. Further, the outer fitting valley portion 33 has a plate thickness tb3 at the third outer fitting step portion 43 larger than a plate thickness tb2 at the second outer fitting step portion 42, and a plate at the fourth outer fitting step portion 44. The thickness tb4 is larger than the plate thickness tb3 at the third external fitting step portion 43.

As for the internal fitting valley part 53, the internal fitting valley part 53 in the 1st internal fitting step part 61 is plate | board thickness tp1, the internal fitting trough part 53 in the 2nd internal fitting step part 62 is plate | board thickness tp2, 3rd internal fitting step The internal fitting valley part 53 in the part 63 has a plate thickness tp3, and the internal fitting valley part 53 in the fourth internal fitting step part 64 has a plate thickness tp4. The internal fitting valley portion 53 is, in particular, the internal fitting step portion 6 adjacent to the axial direction Y, and the thickness of the internal fitting valley portion 53 at the internal fitting step portion 6 on the base end side B in the axial direction Y is In the axial direction Y, the thickness is larger than the plate thickness of the internal fitting valley portion 53 at the internal fitting step portion 6 on the distal end side A.

At this time, the inner fitting valley portion 53 is a plate in the second inner fitting step portion 62 when the inner fitting step portion 6 is provided in four steps from the distal end side A to the proximal end side B in the axial direction Y. The thickness tp2 is larger than the plate thickness tp1 at the first internal fitting step 61. In addition, the inner trough portion 53 has a plate thickness tp3 at the third inner fitting step portion 63 larger than a plate thickness tp2 at the second inner fitting step portion 62, and a plate at the fourth inner fitting step portion 64. The thickness tp4 is greater than the plate thickness tp3 at the third internal fitting step portion 63.

The steel pipe pile joint structure 7 includes the outer fitting step 4 and the inner fitting at positions corresponding to each other in the axial direction Y in a state where the outer fitting end 3 and the inner fitting end 5 are relatively rotated. A stepped portion 6 is arranged. The outer fitting valley portion 33 and the inner fitting valley portion 53 are the outer fitting step portion 4 and the inner fitting step portion 6 that are arranged at positions corresponding to each other, and the outer fitting mountain portion 31 and the inner fitting mountain portion 51 have an axial core. Locked together in direction Y.

At this time, the outer fitting valley portion 33 and the inner fitting valley portion 53 are engaged with the outer fitting mountain portion 31 of the first outer fitting step portion 41 and the inner fitting mountain portion 51 of the fourth inner fitting step portion 64. The outer fitting mountain portion 31 of the second outer fitting step portion 42 and the inner fitting mountain portion 51 of the third inner fitting step portion 63 are locked. Further, the outer fitting valley portion 33 and the inner fitting valley portion 53 are engaged with the outer fitting mountain portion 31 of the third outer fitting step portion 43 and the inner fitting mountain portion 51 of the second inner fitting step portion 62, and The outer fitting mountain portion 31 of the four outer fitting step portion 44 and the inner fitting mountain portion 51 of the first inner fitting step portion 61 are locked.

In the steel pipe pile joint structure 7, in particular, the plate thickness tb1 of the external fitting valley portion 33 in the first external fitting step portion 41 is smaller than the plate thickness tp1 of the internal fitting valley portion 53 in the first internal fitting step portion 61. . Further, the plate thickness tb2 of the external fitting valley portion 33 in the second external fitting step portion 42 is smaller than the plate thickness tp2 of the internal fitting valley portion 53 in the second internal fitting step portion 62. Further, the plate thickness tb3 of the external fitting valley portion 33 in the third external fitting step portion 43 is smaller than the plate thickness tp3 of the internal fitting valley portion 53 in the third internal fitting step portion 63. Further, the plate thickness tb4 of the external fitting valley portion 33 in the fourth external fitting step portion 44 is smaller than the plate thickness tp4 of the internal fitting valley portion 53 in the fourth internal fitting step portion 64.

Further, the joint structure 7 of the steel pipe pile includes the difference Δb in the plate thickness of the external fitting valley portion 33 in the external fitting step portion 4 adjacent in the axial direction Y, and the internal fitting step portion 6 adjacent in the axial direction Y. Δb1 = (tb2−tb1) and Δp3 = (tp4−tp3) are substantially the same, and Δb2 = (tb3−tb2) and Δp2 = (tp3). −tp2) is substantially the same, and Δb3 = (tb4−tb3) and Δp1 = (tp2−tp1) are substantially the same, so that they can be fitted to each other. For this reason, the joint structure 7 of a steel pipe pile determines tb1, tb2, tb3, tb4 by determining the plate thickness tp1 and the plate thickness ratio (tb1 / tp1) that is the ratio between the plate thickness tb1 and the plate thickness tp1. , Tp1, tp2, tp3, and tp4 are all derivable.

For example, in the conventional steel pipe pile joint structure 9 shown in Patent Document 2, as shown in FIG. 11, the plate thickness tb1 is the same as the plate thickness tp1, the plate thickness tb2 is the same as the plate thickness tp2, The thickness tb3 is the same as the plate thickness tp3, and the plate thickness tb4 is the same as the plate thickness tp4. Therefore, when the conventional steel pipe pile joint structure 9 is compared between the first internal fitting step portion 61 and the first external fitting step portion 41, the first internal fitting step portion 61 that is present radially inward is used. However, its cross-sectional area is small. Similarly, the second fitting step 62, the third fitting step 63, and the fourth fitting step 64 have a smaller sectional area in the inner fitting step 6 than in the outer fitting step 4. For this reason, the inner fitting end portion 5 has a smaller cross-sectional area than the outer fitting end portion 3. For this reason, the joint structure 9 of the conventional steel pipe pile determines the proof stress of the inner fitting end portion 5 and the outer fitting end portion 3 on the basis of the destruction of the inner fitting end portion 5 having a small cross-sectional area. The end 3 has the disadvantage of being overdesigned.

In addition, when the tensile force is applied, the external fitting end 3 is deformed so as to expand outward in the axial center orthogonal direction X toward the side opposite to the central axis in the axial direction Y of the first steel pipe pile 1. It is common. On the other hand, the inner fitting end portion 5 is generally deformed so as to shrink inward in the axial center orthogonal direction X toward the central axis in the axial direction Y of the second steel pipe pile 2. For this reason, when the expansion of the stress in the circumferential direction at the time of the action of the tensile force is taken into consideration, the inner fitting end portion 5 is deformed so as to be contracted inward and the stress is not easily spread in the circumferential direction. On the other hand, the outer fitting end portion 3 is deformed so as to spread outward and the stress is easily spread in the circumferential direction, and the stress concentration at the outer fitting end portion 3 is alleviated. Therefore, the conventional steel pipe pile joint structure 9 has the disadvantage that the outer fitting end portion 3 is overdesigned from the viewpoint of the expansion of stress in the circumferential direction and the relaxation of stress concentration in addition to the above-mentioned viewpoint of the cross-sectional area. .

On the other hand, as shown in FIG. 10, the steel pipe pile joint structure 7 according to the present embodiment is configured so that the thickness tb1 of the outer fitting valley portion 33 in the first outer fitting step portion 41 is the first inner fitting step. The plate thickness ratio (tb1 / tp1), which is set to be smaller than the plate thickness tp1 of the internal fitting valley portion 53 at the portion 61 and is the ratio between the plate thickness tb1 and the plate thickness tp1, is set to 0.84 or more.
That is, in the joint structure 7 of the steel pipe pile according to the present embodiment, the plate of the external fitting valley portion 33 closest to the second steel pipe pile 2 rather than the plate thickness of the internal fitting valley portion 53 closest to the first steel pipe pile 1. The ratio obtained by dividing the plate thickness of the external fitting valley portion 33 closest to the second steel pipe pile 2 by the plate thickness of the internal fitting valley portion 53 closest to the first steel pipe pile 1 is 0.84. That's it.

In the steel pipe pile joint structure 7, Δb1 = (tb2−tb1) and Δp3 = (tp4−tp3) are substantially the same, Δb2 = (tb3tp2) and Δp2 = (tp3−tp2) are substantially the same, Δb3 = (tb4−tb3) and Δp1 = (tp2−tp1) are made substantially the same, and the size of the plate thickness tp1 is determined. Furthermore, the thickness of the outer fitting valley portion 33 closest to the second steel pipe pile 2 is smaller than the thickness of the inner fitting valley portion 53 closest to the first steel pipe pile 1, and the first steel pipe pile 1 The ratio obtained by dividing the plate thickness of the outer fitting valley 33 closest to the second steel pipe pile 2 by the plate thickness of the closest inner fitting valley 53 is 0.84 or more. Thereby, the cross-sectional area of the outer fitting end part 3 can be designed on the basis of destruction of the inner fitting end part 5 having a small cross-sectional area. Thereby, the joint structure 7 of a steel pipe pile can design the cross-sectional area of the external fitting end part 3 small according to the internal fitting end part 5 with a small cross-sectional area. Thereby, it becomes possible to avoid the excessive design of the external fitting end part 3, and to reduce the plate | board thickness of the external fitting end part 3, compared with the joint structure 9 of the conventional steel pipe pile.

In addition, as shown in FIG. 12, the shape of the external fitting surplus length part 38 and the internal fitting surplus length part 58 may be changed. By setting it as such a shape, the weight reduction of the joint structure 7 of a steel pipe pile can be achieved.
Here, as shown to (a) of FIG. 13, in the steel pipe pile joint structure 7 which concerns on this embodiment, it is 2nd steel pipe pile rather than the plate | board thickness of the internal fitting valley part 53 nearest to the 1st steel pipe pile 1. As shown in FIG. The thickness of the outer fitting valley portion 33 closest to 2 is smaller. On the other hand, in the conventional steel pipe pile joint structure 9 as shown in FIG. 13 (b), the thickness of the inner valley portion 53 closest to the first steel pipe pile 1 and the second steel pipe pile 2 are The plate thickness of the closest outer fitting valley portion 33 is the same. FIG. 13C is a view showing a comparison between FIG. 13A and FIG. 13B. In FIG. 13 (c), the conventional steel pipe pile joint structure 9 of FIG. 13 (b) is indicated by a dotted line. According to this, it turns out that the direction of the joint structure 7 of the steel pipe pile which concerns on this embodiment has reduced especially the whole thickness of the external fitting end part 3. FIG.

Here, FIG. 14 shows the numerical analysis and the experimental result of the joint yield strength corresponding to the steel pipe pile to be joined in the joint structure of the steel pipe pile according to the present embodiment. The shape ratio according to the present embodiment is applied to provide a design safety factor for designing. In addition, in order to obtain joint strength, the steel pipe pile is calculated as a completely elastic material in the numerical analysis. Further, in the experiment, a steel pipe having a higher strength than the steel pipe corresponding to the original joint is used so that the joint breaks in advance.
The ranges of the steel pipe pile to which the joint is applied were the outer diameter Dp of 400.0 mm to 1600.0 mm, and the steel pipe pile thickness tp of 6.0 mm to 30.0 mm. The material standard is SKK40 defined in JIS A 5525 and SM570 defined in JIS G 3106. The graph of FIG. 14 shows the joint structure 7 of the steel pipe pile according to this embodiment calculated by FEM analysis with the diameter-thickness ratio (Dp / tp) between the outer diameter Dp and the plate thickness tp of the steel pipe pile to be joined as the horizontal axis. The vertical axis is the ratio (Mmax / Mp) of the maximum bending moment Mmax (joint part) of the steel plate and the total plastic bending moment Mp (steel pipe part) of the steel pipe pile. FIG. 14 shows that the maximum bending moment Mmax of the joint exceeds the total plastic bending moment Mp of the steel pipe to be joined even when the plate thickness tb of the external fitting end 3 is reduced. Moreover, since a joint is stronger than a steel pipe, it turns out that this joint does not break prior to a steel pipe. Table 1 shows the numerical data of FIG.

15A and 15B show the grounds that the outer fitting valley portion 33 and the inner fitting valley portion 53 have different plate thicknesses. In FIG. 15A, the horizontal axis represents the diameter-thickness ratio (Dp / tp1) between the outer diameter Dp of the steel pipe pile and the plate thickness tp1 of the inner valley portion 53 in the first inner fitting step portion 61. In FIG. 15A, the maximum bending moment Mmax of the joint structure 7 of the steel pipe pile according to the present embodiment calculated by the FEM analysis and the entire fitting valley portion 53 (when the entire circumference of the valley portion of the joint is made effective) are shown. The yield strength ratio (Mmax / Mf) with the plastic bending moment Mf is taken as the vertical axis. In FIG. 15B, the horizontal axis represents the diameter-thickness ratio (Dp / tb1) between the outer diameter Dp of the steel pipe pile and the plate thickness tb1 of the outer fitting valley portion 33 in the first outer fitting step portion 41. In FIG. 15B, the proof stress ratio (Mmax / Mf) between the maximum bending moment Mmax of the present invention calculated by FEM analysis and the total plastic bending moment Mf of the external fitting valley portion 33 is taken as the vertical axis.
According to FIG. 15A, in the internal fitting end part 5, when the diameter-thickness ratio is changed, the proof stress ratio is also changed, so that the proof stress ratio is a linear function of the diametric thickness ratio. On the other hand, according to FIG. 15B, it can be seen that the proof stress ratio is constant regardless of the diameter-thickness ratio in the externally fitted valley portion 33. 15A and 15B, the normal material standard of the steel pipe pile is within the range where the outer diameter Dp of the steel pipe pile is 400.0 mm to 1600.0 mm and the plate thickness t of the steel pipe pile is 6.0 mm to 30.0 mm. SKK400 defined in JIS A 5525 is shown as the lower limit value of SM, and SM570 defined in JIS G 3106 is shown as the upper limit value of the material standard. Table 2 shows the numerical data of FIGS. 15A and 15B.

Here, as for the joint structure 7 of a steel pipe pile, the outer fitting end part 3 and the inner fitting end part 5 are formed in a cross-sectional substantially circular shape. For this reason, the cross-sectional area of the external fitting valley portion 33 is calculated from π × rb12 ² calculated from the external diameter rb1 of the external fitting valley portion 33 in each external fitting step portion 4 from the internal diameter rb2 of the external fitting valley portion 33. By subtracting the calculated π × rb2 ² , (π × rb1 ² −π × rb2 ² ) is obtained. Since the inner diameter rb2 of the outer fitting valley portion 33 is obtained by subtracting the plate thickness tb from the outer diameter rb1 of the outer fitting valley portion 33, the cross-sectional area of the outer fitting valley portion 33 is equal to that of the outer fitting valley portion 33. It is proportional to the square of the plate thickness tb. Further, the cross-sectional area of the internal fitting valley portion 53 is also proportional to the square of the plate thickness tp of the internal fitting valley portion 53 in each internal fitting step portion 6, similarly to the cross-sectional area of the external fitting valley portion 33. .

As shown in FIG. 15A, the joint structure 7 of the steel pipe pile has a bending moment ratio of 0.70 to 0.50 in the inner fitting end portion 5 in a range where the diameter-thickness ratio is 10.00 to 200.00. Therefore, 70 to 50% of the entire circumference of the internal valley portion 53 is considered to be an effective cross section. On the other hand, in the outer fitting end 3, the bending moment ratio is constant regardless of the diameter-thickness ratio as shown in FIG. 15B, and 70% of the entire circumference of the outer fitting valley 33 is considered to be an effective cross section. .
Therefore, when the diameter-thickness ratio is set to 200.00 and the design is based on the destruction of the inner fitting valley portion 53, the sectional area of the outer fitting valley portion 33 is 71% (0.50 / 0.70≈0). .71). For this reason, since the cross-sectional area of the external fitting valley portion 33 is proportional to the square of the plate thickness tb of the external fitting valley portion 33, the plate thickness tb of the external fitting valley portion 33 is the plate of the internal fitting valley portion 53. Even when the thickness is reduced to 0.84 times the thickness tp (0.84 ² ≈0.71), a cross-sectional area equal to or larger than that of the internal valley portion 53 can be secured. Therefore, the equivalent strength can be ensured by the outer fitting valley portion 33 and the inner fitting valley portion 53. When the diameter-thickness ratio is about 50, the cross-sectional area of the outer fitting valley portion 33 can be reduced to 97% (0.68 / 0.70≈0.97) when designed based on the destruction of the inner fitting valley portion 53. For this reason, since the cross-sectional area of the external fitting valley portion 33 is proportional to the square of the plate thickness tb of the external fitting valley portion 33, the plate thickness tb of the external fitting valley portion 33 is the plate of the internal fitting valley portion 53. Even if the thickness is reduced to 0.94 times the thickness tp (0.97 ² ≈0.94), a cross-sectional area equal to or larger than that of the internal valley portion 53 can be secured.

Thus, in the joint structure 7 of the steel pipe pile according to the present embodiment, the plate of the outer fitting valley portion 33 is larger than the plate thickness tp of the inner fitting valley portion 53 in each of the outer fitting step portion 4 and the inner fitting step portion 6. The thickness tb is reduced. In the steel pipe pile joint structure 7 according to the present embodiment, the thickness of the outer fitting valley 33 closest to the second steel pipe pile 2 is greater than the thickness of the inner fitting valley 53 closest to the first steel pipe pile 1. The ratio obtained by dividing the plate thickness of the external fitting valley portion 33 closest to the second steel pipe pile 2 by the plate thickness of the internal fitting valley portion 53 closest to the first steel pipe pile 1 is 0.84 or more. . Thereby, compared with the joint structure 9 of the conventional steel pipe pile, the joint structure 7 of a steel pipe pile can make the cross-sectional area of the external fitting end part 3 small, and can avoid an excessive design. As a result, the maximum compression, tension, and bending strength can be obtained with a small amount of weight and volume of steel. As a result, the weight and volume of the entire joint can be reduced to improve the efficiency of the connection work, and an increase in the material cost of the entire joint can be suppressed.

Moreover, the joint structure 7 of the steel pipe pile which concerns on this embodiment is the external fitting step part 4 of the base end side B in the external fitting step part 4 adjacent to the axial direction Y, as shown in FIG. 8, FIG. The plate thickness of the external fitting valley portion 33 is larger than the plate thickness of the external fitting valley portion 33 at the external fitting step portion 4 on the distal end side A. At the same time, in the inner fitting step 6 adjacent in the axial direction Y, the thickness of the inner fitting valley portion 53 in the inner fitting step 6 on the base end side B is the same as that in the inner fitting step 6 on the distal end side A. It is larger than the plate thickness of the inner fitting valley portion 53. Further, the protrusion height Hc of the compression surface 31 b of the outer fitting mountain portion 31 and the compression surface 51 b of the inner fitting mountain portion 51 is the protrusion height of the tensile surface 31 a of the outer fitting mountain portion 31 and the tensile surface 51 a of the inner fitting mountain portion 51. Is greater than Ht.
Further, in the first outer fitting step portion 41 and the first inner fitting step portion 61, the second outer fitting step portion 42, the fourth outer fitting step portion 44, and the second inner fitting step portion 62 to the fourth inner fitting step portion. 64, the protrusion height Hc of the compression surface 31b of the outer fitting mountain portion 31 and the compression surface 51b of the inner fitting mountain portion 51 is increased. Thereby, in each of the outer fitting end part 3 and the inner fitting end part 5, it has the characteristic that a compression proof stress becomes larger than a tensile proof stress.

On the other hand, for example, in the conventional steel pipe pile joint structure 9 shown in Patent Document 2, the ratio of Hc to Ht is Ht <0.5 × Hc, as shown in FIG. Hc is very large compared to. For this reason, when the joint structure 9 of the conventional steel pipe pile is calculated by the ratio of the projection height Hc of the compression surface 31b and the compression surface 51b and the projection height Ht of the tension surface 31a and the tension surface 51a, the compressive strength is tensile. More than twice the yield strength. Therefore, in the conventional joint structure 9 of a steel pipe pile, when the tensile strength of the entire joint is equal to or higher than that of the steel pipe pile, the compression strength of the whole joint is more than twice that of the steel pipe pile. Since a general steel pipe pile has the same tensile strength and compression strength, the conventional steel pipe pile joint structure 9 has a drawback that the compression strength is excessively designed.

As shown in FIGS. 8 and 9, the steel pipe pile joint structure 7 according to the present embodiment includes an outer fitting mountain portion 31 and an inner fitting mountain portion 51 in each of the outer fitting step portion 4 and the inner fitting step portion 6. The ratio of the protrusion height Ht of the tension surface 31a and the tension surface 51a of the outer fitting mountain portion 31 and the inner fitting mountain portion 51 to the projection height Hc of the compression surface 31b and the compression surface 51b is 0.5 or more and 0.9. It becomes as follows. At this time, in the joint structure 7 of the steel pipe pile, the protruding height Ht is smaller than the protruding height Hc, and each outer fitting step 4 and inner fitting from the distal end side A to the proximal end side B in the axial direction. The step portion 6 is formed in a substantially tapered shape in the axial direction Y. Thereby, the joint structure 7 of a steel pipe pile can reduce the protrusion height Ht by making the protrusion height Ht smaller than the protrusion height Hc and making the tensile strength of the entire joint equal to the compression strength. Thereby, since it can suppress that a compressive proof stress becomes an excessive design, compared with the joint structure 9 of the conventional steel pipe pile, it becomes possible to reduce the steel material weight of the whole joint.

Here, in FIG. 16, the result of having compared the joint thickness ratio with the joint structure 7 of the steel pipe pile which concerns on this embodiment, and the joint structure 9 of the conventional steel pipe pile is shown. In FIG. 16, when the ratio of Hc to Ht (Ht / Hc) is taken as the horizontal axis and the ratio of Hc to Ht is changed, the joint thickness that can obtain the tensile strength and compression strength equivalent to those of conventional steel pipe piles. The ratio is taken as the vertical axis.

In FIG. 16, the joint thickness ratio when Ht = 0.5 × Hc (corresponding to the examples 2, 9, and 16 in Table 3) and the tensile strength and compression strength equivalent to those of conventional steel pipe piles. When the value is a reference value, the value of the joint thickness ratio on the vertical axis is 1. The joint thickness is h (corresponding to D in FIG. 5), the plate thickness tp4 of the internal fitting valley portion 53 in the fourth internal fitting step portion 64, and the plate thickness of the external fitting valley portion 33 in the first external fitting step portion 41. The total value of tb1 and a predetermined clearance CL is adopted.

In addition, in FIG. 16, SKK400 and SKK490 prescribed | regulated to JISA5525 as a lower limit of the normal material specification of a steel pipe pile, and SM570 prescribed | regulated to JISG3106 as an upper limit of a material specification are shown. Table 3 shows the numerical data of FIG.

As shown in FIG. 16, the steel pipe pile joint structure 7 is a conventional steel pipe pile joint structure 9 in SKK400, SKK490 or SM570, particularly in the range of 0.5 × Hc ≦ Ht ≦ 0.9 × Hc. The joint thickness ratio is smaller than Thereby, it turns out that the weight of the whole coupling becomes small. Further, when the steel pipe pile joint structure 7 is designed in the range of 0.55 × Hc ≦ Ht ≦ 0.8 × Hc, the joint thickness ratio is 5.0% compared to the conventional steel pipe pile joint structure 9. The degree can also be reduced. As a result, the weight of the entire joint after processing can be reduced by about 3.5 to 4.0%.

In addition, if the joint structure 7 of the steel pipe pile is designed in the range of 0.6 × Hc ≦ Ht ≦ 0.8 × Hc in SKK400 or SKK490, the joint thickness ratio can be reduced by about 10%. At the same time, in SM570, when the design is made in the range of 0.6 × Hc ≦ Ht ≦ 0.7 × Hc, the joint thickness ratio can be reduced by about 10%.
Thereby, the joint structure 7 of the steel pipe pile reduces the protrusion height Hc by setting the ratio of the protrusion height Ht to the protrusion height Hc to 0.5 or more and 0.9 or less, and avoids excessive design of compression strength. it can. Thereby, compared with the conventional steel pipe pile joint structure 9, the maximum compressive strength, tensile strength, and bending strength can be obtained with a small amount of used weight and volume of steel. As a result, the weight and volume of the entire joint can be reduced to improve the efficiency of the connection work, and an increase in the material cost of the entire joint can be suppressed.

In the joint structure 7 of the steel pipe pile according to the present embodiment, in each of the external fitting mountain parts 31, the external fitting mountain part 31 is based on the protruding height Hc of the external fitting mountain part 31 that is relatively close to the second steel pipe pile 2. The ratio obtained by dividing the projecting height Ht of the other external fitting mountain portion 31 adjacent to each other is 0.5 or more and 0.9 or less, and each of the internal fitting mountain portions 51 is relatively first. The ratio obtained by dividing the projection height Ht of the other internal fitting mountain portion 51 adjacent to the internal fitting mountain portion 51 by the projection height Hc of the internal fitting mountain portion 51 close to the steel pipe pile 1 is 0.5 or more. 0.9 or less.

As shown in FIG. 17, a predetermined clearance CL usually exists in the radial direction that is the axial direction X. For this reason, in consideration of the clearance CL, the relationship between the effective protrusion height Hc ′ (= Hc−1.5 × CL) and Ht ′ (= Ht−1.5 × CL) is also shown above. The relationship (0.5 × Hc ′ ≦ Ht ′ ≦ 0.9 × Hc ′) is preferably established.

Further, in order to prevent the outer fitting mountain portion 31 and the inner fitting mountain portion 51 from being detached when a tensile force or a bending force is applied, it is desirable to set a lower limit value of the protrusion height Ht. Here, when the bending test of three cases where the outer diameter Dp of the steel pipe pile was changed to 800.0 mm and Ht was changed to 2.4 mm, 3.3 mm, and 4.2 mm was performed, as shown in FIG. At 2.4 mm, the maximum proof stress is determined by the separation between the outer fitting mountain portion 31 and the inner fitting mountain sound 1551. On the other hand, at Ht = 3.3 mm or more, the maximum proof stress is determined by the bearing failure of the outer fitting mountain portion 31 or the inner fitting mountain portion 51. For this reason, when aiming for a stable destruction situation as a support pressure failure rather than separation between the outer fitting mountain portion 31 and the inner fitting mountain portion 51, Ht ≧ Dp / 250 as a lower limit value of the protrusion height Ht. It is desirable to do.

According to the steel pipe pile joint structure 7 according to the above-described embodiment, the plate of the outer fitting valley portion 33 located closest to the outer fitting tip side with respect to the plate thickness of the inner fitting valley portion 53 located closest to the inner fitting tip side. By reducing the thickness and defining the ratio of these plate thicknesses, it is possible to reduce the weight of the joint while ensuring a desired strength. Therefore, the joint weight of the steel pipe pile can be reduced, and workability is improved.

Second Embodiment
The second embodiment of the present invention will be described below, but basically corresponds to a modified example of the first embodiment. Therefore, the second embodiment of the present invention will be described using the same reference numerals as those used in the first embodiment. Is omitted.
That is, this embodiment is basically the same configuration as the first embodiment, but the second steel pipe pile 2 is the most in accordance with the thickness of the inner valley portion 53 closest to the first steel pipe pile 1. The ratio obtained by dividing the plate thickness of the close fitting valley portion 33 is 0.84 or more and 0.94 or less.

In FIG. 19, the first inner fitting is based on the diameter-thickness ratio (Dp / tb1) between the outer diameter Dp of the conventional steel pipe pile and the plate thickness tb1 of the outer fitting valley portion 33 in the first outer fitting step portion 41. A graph with the vertical axis representing the plate thickness ratio (tb1 / tp1) between the plate thickness tp1 of the internal fitting valley portion 53 at the step portion 61 and the plate thickness tb1 of the external fitting valley portion 33 at the first external fitting step portion 41. Show. According to this, when the material of the steel pipe is SM570 material or the steel pipe plate thickness is thick, the outer fitting valley plate thickness is in the thick range (D / tp1 is 50 or less). For this reason, the plate thickness ratio of the internal fitting valley part 53 and the external fitting valley part 33 is 0.94 or more, and there is almost no difference between the conventional structure. In the range where the diameter-thickness ratio is in the range of 50 to 150, the weight can be preferably reduced. Therefore, the thickness ratio is more preferably 0.84 or more and 0.94 or less. About the plate | board thickness ratio of the external fitting trough part 33 and the internal fitting trough part 53, the linear relationship shown to the following formula | equation 1 is formed between diameter thickness ratios.
(Tb1 / tp1) = 0.99−0.001 × (Dp / tb1) (Formula 1)

According to the joint structure 7 of the steel pipe pile according to the present embodiment, the thickness of the outer fitting end portion 3 having a larger influence on the joint weight than the inner fitting end portion 5 can be obtained by setting the ratio of the plate thickness within the above range. It can be made smaller, and the weight of the entire joint can be further reduced. Therefore, it is possible to further reduce the weight of the steel pipe pile joint.

<Third Embodiment>
The third embodiment of the present invention will be described below, but basically corresponds to a modification of the first embodiment. Therefore, the same reference numerals as those used in the first embodiment are used for explanation and illustration. Is omitted.
That is, this embodiment is basically the same configuration as the first embodiment, but in each outer fitting mountain portion 31, the outer fitting mountain portion 31 which is relatively close to the second steel pipe pile 2 is used. The ratio obtained by dividing the protrusion height of the other external fitting mountain part 31 adjacent to the external fitting mountain part 31 by the projection height is 0.6 or more and 0.8 or less, and each internal fitting mountain part 51, the ratio obtained by dividing the protrusion height of the other internal fitting mountain portion 51 adjacent to the internal fitting mountain portion 51 by the protruding height of the internal fitting mountain portion 51 that is relatively close to the first steel pipe pile 1. 0.6 or more and 0.8 or less.

According to the joint structure of the steel pipe pile according to the present embodiment, the ratio of the protruding height of the ridge portion on the proximal end side to the protruding height of the ridge portion on the distal end side is within the above range, thereby being parallel to the axis L. A sufficient strength in any direction can be ensured. Therefore, the weight of the steel pipe pile joint can be reduced while maintaining the strength of the steel pipe pile joint.

As mentioned above, although each embodiment of this invention was described in detail, all the embodiment mentioned above showed only the example of implementation in implementing this invention. Therefore, the technical scope of the present invention should not be limitedly interpreted only by these.

For example, the joint structure 7 of the steel pipe pile which concerns on each said embodiment cuts the edge part of the 1st steel pipe pile 1 and the 2nd steel pipe pile 2, and is the edge part of the 1st steel pipe pile 1 or the 2nd steel pipe pile 2 The outer fitting end 3 or the inner fitting end 5 may be provided in itself. The first steel pipe pile 1 may be provided with the inner fitting end 5, and the second steel pipe pile 2 may be provided with the outer fitting end 3.

The joint structure of a steel pipe pile according to the present invention can reduce the joint weight while ensuring a desired strength. Therefore, the joint weight of the steel pipe pile can be reduced, and a steel pipe pile with improved workability can be provided. Therefore, the present invention has high industrial applicability.

1: 1st steel pipe pile 2: 2nd steel pipe pile 3: Outer fitting end part 31: Outer fitting mountain part 31a: Tensile surface 31b: Compression surface 32: Outer fitting groove part 33: Outer fitting trough part 38: Outer fitting extra length part 4: external fitting step part 41: 1st external fitting step part 42: 2nd external fitting step part 43: 3rd external fitting step part 44: 4th external fitting step part 5: internal fitting end part 51: internal fitting mountain part 51a: Tensile surface 51b: Compression surface 52: Internal fitting groove portion 53: Internal fitting valley portion 58: Internal fitting extra length portion 6: Internal fitting step portion 61: First fitting step portion 62: Second fitting step portion 63: 3rd internal fitting step part 64: 4th internal fitting step part 7: Joint structure A of steel pipe pile: Tip side B: Proximal end side L: Shaft core line W: Circumferential direction X: Shaft core orthogonal direction Y: Shaft core direction

Claims (3)

The steel pipe which the 1st steel pipe pile which has an external fitting end part, and the 2nd steel pipe pile which has an internal fitting end part were connected in the state which shared the same axial center line in the said external fitting end part and the said internal fitting end part A pile joint structure,
When viewed in cross-section along the axis:
An outer fitting step portion is provided at a plurality of positions along the axial center line inside the outer fitting end portion so as to gradually expand the diameter toward the second steel pipe pile,
Each said external fitting step part has an external fitting mountain part relatively close to the said 2nd steel pipe pile, and an external fitting valley part adjacent to the said external fitting mountain part;
An inner fitting step portion is provided at a plurality of positions along the axial center line outside the inner fitting end portion so as to gradually reduce the diameter toward the first steel pipe pile,
Each of the internal fitting step portions has an internal fitting mountain portion relatively close to the first steel pipe pile, and an internal fitting valley portion adjacent to the internal fitting mountain portion,
Each of the internal fitting ridges is locked to each of the external fitting ridges in a state in which the internal fitting end is inserted into the external fitting end and is rotated relative to the axis line;
In each of the external fitting mountain portions, the protruding height of the external fitting mountain portion adjacent to the external fitting mountain portion is divided by the protruding height of the external fitting mountain portion that is relatively close to the second steel pipe pile. The ratio is 0.5 or more and 0.9 or less,
In each of the internal fitting mountain portions, the protruding height of the internal fitting mountain portion adjacent to the internal fitting mountain portion is divided by the protruding height of the internal fitting mountain portion that is relatively close to the first steel pipe pile. The ratio is 0.5 or more and 0.9 or less,
The plate thickness of the outer fitting valley portion closest to the second steel pipe pile is smaller than the plate thickness of the inner fitting valley portion closest to the first steel pipe pile, and is closest to the first steel pipe pile. The ratio obtained by dividing the plate thickness of the outer fitting valley portion closest to the second steel pipe pile by the plate thickness of the inner fitting valley portion is 0.84 or more;
A steel pipe pile joint structure characterized by that. The ratio obtained by dividing the plate thickness of the outer fitting valley portion closest to the second steel pipe pile by the plate thickness of the inner fitting valley portion closest to the first steel pipe pile is 0.84 or more and 0.94 or less. The steel pipe pile joint structure according to claim 1, wherein the steel pipe pile joint structure is provided. In each of the external fitting mountain portions, the protruding height of the external fitting mountain portion adjacent to the external fitting mountain portion is divided by the protruding height of the external fitting mountain portion that is relatively close to the second steel pipe pile. The ratio is 0.6 or more and 0.8 or less,
In each of the internal fitting mountain portions, the protruding height of the internal fitting mountain portion adjacent to the internal fitting mountain portion is divided by the protruding height of the internal fitting mountain portion that is relatively close to the first steel pipe pile. The ratio is 0.6 or more and 0.8 or less,
The joint structure for steel pipe piles according to claim 1 or 2.

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