JP2013053425A - Connection structure of different-diameter steel pipes - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a connection structure suitable for the connection of a part turned to a double pipe structure by inserting an inner pipe to an outer pipe for a prescribed length and filling grout in a gap between the outer pipe and the inner pipe.SOLUTION: In order to efficiently transmit weight of an upper structure or the like supported by an outer pipe from grout to an inner pipe without using a shear key, either inner diameter of an outer pipe 1 or outer diameter of an inner pipe 2 in a double pipe area is changed in a pipe axis direction, and a part of shear force acting on the grout is made to act in a radial direction of the inner pipe 2. In the double pipe area where the inner pipe 2 is inserted to the outer pipe 1 for a prescribed length and the outer pipe 1 and the inner pipe 2 are connected through the grout, the inner diameter of the outer pipe 1 is fixed in the pipe axis direction and the outer diameter of the inner pipe 2 is gradually reduced toward the inserted distal end, or the inner diameter of the outer pipe 1 is gradually enlarged toward the end and the outer diameter of the inner pipe 2 is fixed in the pipe axis direction toward the inserted distal end.

Description

  The present invention relates to a joint structure in which steel pipes with different diameters are joined with a double pipe structure via a grout with the same axis, and the tower body is an outer pipe at the tower-like structure base having the steel pipe as a tower body. The present invention relates to a suitable joining structure for a portion having a double pipe structure with a steel pipe pile as an inner pipe.

  Structures mainly composed of steel pipes include oil drilling rigs, piers, and wind power generation facilities, and various steel pipe joint structures are used.

  In patent document 1, in the description of the conventional technique, the steel pipe joint structure is as follows. Butt welding, 2. 2. bolt connection; Double tube structure, 4. 4. Screw system, Inro method, 6. Although they are classified as a taper type, both are joint structures of steel pipes having the same diameter.

  On the other hand, in the case of steel pipes having different diameters, there is a joining structure shown in FIGS. 8A, 8B, and 8C, which is used for a monopile type offshore wind power generator (shown schematically in FIG. 9). ing.

  In the case of a monopile type offshore wind power generator, the joint portion 11 is shown in FIG. 8 (b) through a grout 3 (concrete or the like) with the upper structure 9 side being the outer tube 1 and the lower structure 10 side being the inner tube 2. As shown in FIGS. 8 (a) and 8 (c), a shear key 4 (shear force transmission) in which a reinforcing bar is welded to the inner tube 2 or both the inner tube 2 and the outer tube 1 is used. Member) is often provided.

  By the shear key 4 (shearing force transmission member), the shearing force between the outer tube 1 and the inner tube 2 is efficiently transmitted to the grout 3, and the total weight of the upper structure 9 is reliably supported by the inner tube 2.

  In the case of the joint shown in FIG. 8B, since there is no shear key (shearing force transmission member) 4 as shown in FIGS. 8A and 8C, the adhesion between the grout 3 and the surface of the steel pipe is cut off. The shear force does not act effectively on the grout 3, and the outer tube 1 that supports the total weight of the upper structure 9 falls due to gravity.

  Further, in Patent Document 1, the end of the first hollow tube having an inward flange facing the inside of the tube has a smaller diameter than the first hollow tube and an outward flange facing the outside of the tube is formed. A hollow tube joining structure is proposed in which two hollow tubes are inserted and a curing agent is filled between both flanges.

JP-A-5-339937

  However, in the structure in which the shear key 4 shown in FIGS. 8A and 8C is attached, the acting stress becomes high due to the stress concentration in the vicinity of the shear key 4, so that the grout 3 may break near the shear key.

  If the grout 3 breaks near the shear key, the stress is redistributed even if it is a local break, so that it progresses not only to a local break but also to an overall break. However, the outer tube 1 does not support the total weight of the superstructure and falls downward.

  In the case of the hollow tube joining structure described in Patent Document 1, the flange is so that the outward flange attached to the second hollow tube is inserted inside the inward flange attached to the first hollow tube. Therefore, it is necessary to manage and manufacture the dimensions and to attach them, and it is not easy to manage the construction when assembling the joints in the field.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a joining structure suitable for a base structure such as a monopile type offshore wind power generator that can prevent the outer pipe from dropping due to gravity with a simple structure that does not use a shear key.

The object of the present invention can be achieved by the following means.
1. A joint structure of different diameter steel pipes in which steel pipes having different diameters are joined to each other with their axes aligned, and a second steel pipe is inserted into the first steel pipe by a predetermined length, and the first steel pipe and the first steel pipe In the double pipe region where the two steel pipes are joined via the grout, the inner diameter of the first steel pipe or the outer diameter of the second steel pipe is set so that the cross section in the pipe axis direction of the grout is substantially wedge-shaped. A joint structure for steel pipes with different diameters characterized by being gradually changed in the axial direction.
2. A joint structure of different diameter steel pipes in which steel pipes having different diameters are joined to each other with their axes aligned, and a second steel pipe is inserted into the first steel pipe by a predetermined length, and the first steel pipe and the first steel pipe In a double pipe region in which two steel pipes are joined via a grout, the inner diameter of the first steel pipe is constant in the pipe axis direction, and the outer diameter of the second steel pipe is gradually reduced toward the inserted tip. A joint structure of different diameter steel pipes characterized by having a diameter.
3. 3. The joint structure of different diameter steel pipes according to 2, wherein the inner diameter of the second steel pipe is gradually reduced along the outer diameter in the double pipe region.
4). The joint structure of different diameter steel pipes according to claim 2, wherein the inner diameter of the second steel pipe in the double pipe region is constant in the pipe axis direction.
5. A joint structure of different diameter steel pipes in which steel pipes having different diameters are joined to each other with their axes aligned, and a second steel pipe is inserted into the first steel pipe by a predetermined length, and the first steel pipe and the first steel pipe In the double pipe region where the two steel pipes are joined via a grout, the inner diameter of the first steel pipe gradually increases toward the end, and the outer diameter of the second steel pipe faces the inserted tip. A joint structure of different diameter steel pipes characterized by being constant in the pipe axis direction.

  According to the present invention, when joining steel pipes having different diameters, either the inner diameter of the outer pipe or the outer diameter of the inner pipe in the double pipe region is changed in the pipe axis direction. In addition, the grout filled in the gap between the outer pipe and the inner pipe is restrained with a simple structure without attaching a flange to the inner pipe and the safety is remarkably improved, which is extremely useful industrially.

The axial sectional view cut | disconnected by the axial center in the figure by the figure explaining the joining structure of the different diameter steel pipe which concerns on one Example of this invention. The external view of the truncated cone-shaped front-end | tip part of an inner pipe in the joining structure of the different diameter steel pipe shown in FIG. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the principle of the joining structure of the outer tube | pipe and inner tube | pipe which concerns on this invention, (a) is a joining structure with an outer tube | pipe upper direction of the inner tube | pipe, (b) The figure explaining the wedge effect of a grout. The figure explaining the joining structure of the different diameter steel pipe which concerns on the other Example of this invention. The external view at the time of manufacturing the truncated cone-shaped tip part of an inner pipe with LP steel plate. The figure explaining the joining structure of the different diameter steel pipe which concerns on the other Example of this invention. (A) shows the joint structure in the case where the inner diameter of the outer tube and the outer diameter of the inner tube in the double tube region are constant and the gap filled with grout does not change in the tube axis direction (conventional example), (b) FIG. 6 is a diagram for explaining the deformation of the grout due to the shearing force in the case of (a). An example of a joining structure in which steel pipes having different diameters are joined together through a grout is shown. (A) shows a case where a shear key is attached to the inner pipe, (b) shows a case where no shear key is attached, and (c) shows a case where the shear key is inside. The figure which shows the case where it attaches to a pipe | tube and an outer pipe | tube. The figure which shows the general | schematic structure of a monopile type offshore wind power generator.

  In the present invention, in order to efficiently transmit the weight of the upper structure supported by the outer pipe without using a shear key from the grout to the inner pipe, the cross section in the pipe axial direction of the grout is substantially wedge-shaped. Either the inner diameter of the outer tube or the outer diameter of the inner tube is changed in the tube axis direction. Hereinafter, it explains in detail using a drawing.

  FIG. 1 is a view for explaining a joint structure of different diameter steel pipes according to an embodiment of the present invention, and shows an axial sectional view cut along an axial center in an axial direction. In the figure, 1 is the outer tube, 2 is the inner tube, 2a is the tip of the inner tube 2, 3 is the grout, 5 is the inner tube 2 inserted into the outer tube 1, and the grout is between the outer tube and the inner tube. 3 shows a region filled with a double pipe.

  The outer tube 1 and the inner tube 2 have the inner tube 2 inserted into the outer tube 1 by a predetermined length with the axial center aligned. In the region 5 in which the inner tube 2 is inserted into the outer tube 1 to form a double tube, the outer tube 1 and the inner tube 2 are joined via a grout 3. The grout 3 appropriately adjusts the filling amount in the region 5 so that a desired bonding strength can be obtained.

  In the case of the illustrated joining structure, the inner diameter of the outer tube 1 in the region 5 is constant in the tube axis direction, the outer diameter of the inner tube 2 is gradually reduced toward the tip of the inserted portion, and the grout 3 extends in the tube axis direction. The cross-sectional shape is substantially wedge-shaped and filled. FIG. 2 is an external view showing an example of a truncated cone-shaped tip portion 2a in which the outer diameter of the inner tube 2 is gradually reduced toward the tip. The inner diameter of the inner tube 2 is gradually reduced along the outer diameter.

  3A and 3B are views for explaining the principle of the joining structure of the outer tube 1 and the inner tube 2 according to the present invention. FIG. 3A is a joining structure in which the outer tube 1 is above the inner tube 2 in the vertical direction. FIG. 4A is a diagram illustrating the wedge effect of the grout 3 in the A part of FIG.

  A shear strain γ (between arrows b) is generated in the grout 3 due to the self-weight of the outer tube 1 and the shearing force (indicated by the arrow a) due to the load supported by the outer tube 1. Since the deformation of the grout 3 due to the shearing force (indicated by the arrow a) is an elastic deformation, the volume deformation C due to the shear strain γ (between the arrows b) is generated but is blocked by the outer tube 1 and the wedge effect is generated. To do.

  The grout 3 is constrained between the distal end portion 2a of the inner tube 2 and the outer tube 1 so that the cross-sectional shape in the tube axis direction is substantially wedge-shaped, so that the gap between the outer tube 1 and the inner tube 2 becomes narrower in the vertical direction. , The outer tube 1 is pushed outward with a force corresponding to the volume deformation c, so that a resistance force against the pushing force, that is, a resistance force as a wedge effect is obtained, and the outer tube 1 is prevented from falling. . Due to the inclination of the gap filled with the grout 3, a wedge effect is generated, and a joining structure that can transmit force reliably without causing local stress concentration as in the case of using a shear key is obtained.

  When the inner diameter of the outer tube 1 and the outer diameter of the inner tube 2 in the double tube region are constant and the gap filled with the grout 3 does not change in the tube axis direction (FIG. 7A), the shear force a Although the shear strain γ is generated in the grout 3, the grout 3 is deformed without changing the distance between the inner tube 2 and the outer tube 1 (FIG. 7B). In this case, the joining of the inner tube 2, the outer tube 1 and the grout 3 depends only on the adhesion between steel and concrete.

  FIG. 4 is an axial sectional view cut along an axial center in the axial direction, illustrating a joint structure of different diameter steel pipes according to another embodiment of the present invention. In the double tube region, the outer diameter of the inner tube 2 gradually decreases toward the tip of the inserted portion, and the inner diameter of the inner tube 2 is constant in the tube axis direction.

  FIG. 5 shows an external view of the tip 2a of the inner tube 2 shown in FIG. It can be manufactured using LP steel plate (also referred to as Longitudinally Profiled Plate, also called tapered steel plate) 6 whose thickness changes in the rolling direction.

  In the above description, the cross-sectional shape of the grout 3 in the tube axis direction is a substantially wedge shape in which the inner tube side of the double tube region is tapered, but the outer tube side of the double tube region is tapered as shown in FIG. It is good also as a substantially wedge shape. In the case where the outer diameter of the inner tube 2 in the double tube region is constant and the inner diameter of the outer tube 1 is gradually increased toward the end, the double tube region of the outer tube 1 is made of LP steel plate (Longitudinally Profiled Plate, taper (It is also called a steel plate).

  The joint structure of different diameter steel pipes according to the present invention is applied to the joint structure of the lower structure consisting of the upper structure (corresponding to the outer pipe) and the steel pipe pile (corresponding to the inner pipe) at the base of the tower structure of the monopile offshore wind power generator. Then, it is possible to prevent the superstructure from falling due to weight, and the safety is remarkably improved.

DESCRIPTION OF SYMBOLS 1 Outer tube 2 Inner tube 3 Grout 4 Shea key 5 Area | region 6 LP steel plate part 7 Shear force C Volume deformation part 9 Upper structure 10 Lower structure 11 Joint part

Claims (5)

  A joint structure of different diameter steel pipes in which steel pipes having different diameters are joined to each other with their axes aligned, and a second steel pipe is inserted into the first steel pipe by a predetermined length, and the first steel pipe and the first steel pipe In the double pipe region where the two steel pipes are joined via the grout, the inner diameter of the first steel pipe or the outer diameter of the second steel pipe is set so that the cross section in the pipe axis direction of the grout is substantially wedge-shaped. A joint structure for steel pipes with different diameters characterized by being gradually changed in the axial direction.   A joint structure of different diameter steel pipes in which steel pipes having different diameters are joined to each other with their axes aligned, and a second steel pipe is inserted into the first steel pipe by a predetermined length, and the first steel pipe and the first steel pipe In a double pipe region in which two steel pipes are joined via a grout, the inner diameter of the first steel pipe is constant in the pipe axis direction, and the outer diameter of the second steel pipe is gradually reduced toward the inserted tip. A joint structure of different diameter steel pipes characterized by having a diameter.   The joint structure of different diameter steel pipes according to claim 2, wherein the inner diameter of the second steel pipe in the double pipe region is gradually reduced along the outer diameter.   The joint structure of different diameter steel pipes according to claim 2, wherein the inner diameter of the second steel pipe in the double pipe region is constant in the pipe axis direction.   A joint structure of different diameter steel pipes in which steel pipes having different diameters are joined to each other with their axes aligned, and a second steel pipe is inserted into the first steel pipe by a predetermined length, and the first steel pipe and the first steel pipe In the double pipe region where the two steel pipes are joined via a grout, the inner diameter of the first steel pipe gradually increases toward the end, and the outer diameter of the second steel pipe faces the inserted tip. A joint structure of different diameter steel pipes characterized by being constant in the pipe axis direction.