Corrosion-resistant structure

Abstract

To provide a corrosion-proof structure capable of highly protecting a surface of a wall in which neighboring steel pipe bodies are connected via a joint.SOLUTION: A corrosion-proof structure disposed on a surface of a wall in which neighboring steel pipe bodies are connected via a joint includes at least a corrosion-proof layer and a corrosion-resistant layer, and fixing means for fixing these to the wall. The corrosion-proof structure includes a bead layer filled with bead-like foam between an outer surface of the joint and an inner surface of the corrosion-resistant layer. The fixing means is not fixed to the joint, and is fixed to an outer surface of the steel pipe body.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a corrosion-resistant structure. [Background technology]

[0002] Conventionally, a corrosion prevention method has been applied in which a corrosion prevention structure is installed on the surface of a steel pipe sheet pile. One such corrosion prevention method is to form a corrosion prevention layer made of an organic resin or the like on the surface of the steel pipe sheet pile, and then to attach and fix a corrosion-resistant layer to the surface to install a corrosion prevention structure. By carrying out such anticorrosion treatment, it is possible to impart long-term corrosion resistance to the steel pipe sheet pile. Such corrosion prevention methods are described in Patent Documents 1 to 3, for example. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-28949 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-194215 [Patent Document 3] Japanese Utility Model Application Publication No. 6-1991 Summary of the Invention [Problem to be solved by the invention]

[0004] Examples of walls formed by connecting adjacent steel pipe bodies via joints include steel pipe sheet piles that are at least part of existing structures such as marine structures and river structures, and continuous walls formed using the Gyropress method (registered trademark). If such walls are located in environments exposed to seawater, such as splash zones or tidal zones, or similar environments, the walls may require corrosion protection.

[0005] In walls such as steel pipe sheet piles and diaphragm walls constructed using the Gyropress Method (registered trademark), the relative position of the steel pipe body and the joint varies greatly, and the relative position of the joint to the steel pipe body tends to fluctuate even after installation. Therefore, when a fixing means for fixing a corrosion-resistant layer or a corrosion-protective layer to the outer surface is attached to the joint, it is difficult to properly install the corrosion-resistant layer or the corrosion-protective layer on the outer surface of the wall. Even if the corrosion-resistant layer or the corrosion-protective layer is installed, gaps may form between the corrosion-resistant layer or the wall, making it difficult to maintain the corrosion-resistant layer in the appropriate position over the long term. Therefore, it has sometimes been difficult to achieve a high level of corrosion protection for the wall surface.

[0006] An object of the present invention is to provide a corrosion-resistant structure that can highly protect the surface of a wall formed by connecting adjacent steel pipe bodies via joints. [Means for solving the problem]

[0007] The present inventors have conducted extensive research and found a method for solving the above problems, thereby completing the present invention. The present invention includes the following (1) to (5). (1) A corrosion prevention structure including at least a corrosion prevention layer and a corrosion-resistant layer disposed on the surface of a wall where adjacent steel pipe bodies are connected via joints, and a fixing means for fixing them to the wall, a bead layer formed by filling a bead-shaped foam between the outer surface of the joint and the inner surface of the corrosion-resistant layer; A corrosion prevention structure, wherein the fixing means is not fixed to the joint but is fixed to the outer surface of the steel pipe body. (2) In a cross section perpendicular to the central axis of the steel pipe body, A corrosion-resistant structure as described in (1) above, wherein the angle formed by the line connecting the points indicating the central axes of two adjacent steel pipe bodies and the line connecting the points indicating the central axes and the location of the fixing means is 20 to 50 degrees. (3) A corrosion-resistant structure as described in (1) or (2) above, wherein the fixing means includes a fixing plate fixed to the steel pipe body, a bolt fixed to the fixing plate, and a nut screwed onto the bolt, and the bolt is passed through the corrosion-protective layer and the corrosion-resistant layer, and then screwed onto the nut to fix it to the outer surface of the steel pipe body. (4) The corrosion-resistant structure according to any one of (1) to (3) above, further comprising a cushion layer between the corrosion-resistant layer and the corrosion-protection layer. (5) The corrosion-resistant structure according to (4) above, further comprising a waterproof sheet between the corrosion-resistant layer and the cushion layer. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a corrosion-resistant structure that can highly protect the surface of a wall formed by connecting adjacent steel pipe bodies via joints. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view showing the corrosion prevention structure of the present invention attached to the sea side of a steel pipe sheet pile installed on a revetment G. FIG. [Figure 2] FIG. 1 is a schematic cross-sectional view showing a state in which the corrosion prevention structure of the present invention is attached to the sea side of a continuous wall installed on land L by the Gyropress method (registered trademark). [Figure 3] FIG. 10 is a schematic cross-sectional view showing the state in which the corrosion prevention structure of the present invention is attached to the sea side of another continuous wall installed on land L by the Gyropress method (registered trademark). DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will now be described. The present invention is a corrosion prevention structure that includes at least a corrosion protection layer and a corrosion-resistant layer, which are placed on the surface of a wall where adjacent steel pipe bodies are connected via joints, and a fixing means for fixing them to the wall, and has a bead layer filled with bead-like foam between the outer surface of the joint and the inner surface of the corrosion-resistant layer, and the fixing means is not fixed to the joint but is fixed to the outer surface of the steel pipe body. Such a corrosion-resistant structure will be referred to below as the "corrosion-resistant structure of the present invention."

[0011] Specific embodiments of the corrosion prevention structure of the present invention will be described with reference to the drawings. The embodiments described below with reference to the drawings are preferred examples of the corrosion prevention structure of the present invention, and the corrosion prevention structure of the present invention is not limited to these.

[0012] [Embodiment 1] Figure 1 is a schematic cross-sectional view showing a steel pipe sheet pile 1, which is at least part of an offshore structure, installed on a revetment G, with a corrosion prevention structure 2 of the present invention attached to the sea S side (outside) of the steel pipe sheet pile 1. The specific embodiment of the corrosion-resistant structure of the present invention shown in FIG. 1 will hereinafter also be referred to as "embodiment 1." The side of a marine structure where water such as seawater is present is also called the "outside," and the opposite side is called the "inside." In the case of embodiment 1, the side of the sea S facing the revetment G is the "outside," and the opposite side is the "inside."

[0013] In Fig. 1, a steel pipe sheet pile 1 has a steel pipe body 11 with a circular cross section formed from a long cylindrical steel material, and a joint 12 arranged so as to be sandwiched between two steel pipe bodies 11. The steel pipe bodies 11 are connected by the joints 12 to form a wall.

[0014] The joint 12 consists of a cylinder with a smaller diameter than the steel pipe body 11, and a portion of its circumference is cut off, and another cylinder is inserted into this cut portion to form the joint 12. This type of joint 12 is called a PP type. In the corrosion-resistant structure of the present invention, the joint does not have to be a PP type, and may be, for example, a PT type or an LT type.

[0015] The steel pipe sheet pile 1 of the first embodiment is used to construct a quay structure of a port facility. In such an application, corrosion is likely to progress due to exposure to seawater. Therefore, the corrosion-resistant structure 2 of the present invention can be preferably applied to the steel pipe sheet pile 1.

[0016] In embodiment 1, the corrosion-resistant structure 2 of the present invention includes a corrosion-resistant layer 21 formed on the surface of a steel pipe sheet pile 1. Also, a cushion layer 23 is provided on the outside of the portion of the corrosion-resistant layer 21 formed on the surface of the steel pipe body 11. Also, a bead layer 25 is provided on the outside of the portion of the corrosion-resistant layer 21 formed on the surface of the joint 12. And, on the outside of the cushion layer 23 and the bead layer 25, a corrosion-resistant layer 27 is provided as the outermost layer. These layers are fixed to the surface of the steel pipe sheet pile 1 by fixing means 29 fixed to the surface of the steel pipe body 11 so as to be in close contact with the surface.

[0017] <Corrosion prevention layer> In the first embodiment, the anticorrosion layer 21 is provided so as to be in close contact with the outer surface of the steel pipe sheet pile 1. That is, it is provided so as to be in close contact with the outer surface of the steel pipe body 11 and the outer surface of the joint 12.

[0018] The anticorrosion layer 21 can be formed using a conventionally known anticorrosive agent. For example, the anticorrosion layer can be formed using commercially available anticorrosive agents such as petrolatum (petrolatum paste, petrolatum sheet), epoxy resin, and oxidative polymerization resin. For example, the anticorrosion layer can be formed by applying petrolatum paste to the surface of the steel pipe sheet pile 1 and then attaching a petrolatum sheet to the outer surface.

[0019] The amount of the anticorrosion layer 21 provided so as to be in close contact with the outer surface of the steel pipe sheet pile 1 is 2.0 to 4.0 kg / m as the mass of the anticorrosion layer per unit area of ​​the outer surface of the steel pipe sheet pile 1. 2 It is preferable that the density is 2.0 to 3.0 kg / m 2 More preferably, it is 2.0 to 2.5 kg / m 2 More preferably, it is 2.0 to 2.2 kg / m 2It is more preferable that: Furthermore, the thickness of the anticorrosion layer 21 is not particularly limited, but is preferably 2 to 5 mm, more preferably 2 to 4 mm, and even more preferably 2 to 3 mm.

[0020] <Cushion layer> In embodiment 1, a cushion layer 23 is provided on the outside of the portion of the corrosion protection layer 21 formed on the outer surface of the steel pipe body 11. Here, it is preferable that the cushion layer 23 exists up to the vicinity of the boundary between the steel pipe body 11 and the joint 12. For example, a bead layer 25 may exist instead of the cushion layer 23 on the side of the fixing means 29 closer to the joint 12. The position of the boundary between the cushion layer 23 and the bead layer 25 does not necessarily have to be precise, as long as it is near the boundary between the steel pipe body 11 and the joint 12. It is preferable that the cushion layer 23 and the bead layer 25 are in contact near this boundary, with no gap between them.

[0021] It should be noted that the cushion layer 23 is not essential to the corrosion-resistant structure of the present invention.

[0022] The cushion layer 23 is a sheet made of a cushioning material. Examples of the buffer material include foamed polyethylene, foamed urethane, and foamed polystyrene. The thickness of the cushion layer 23 is not particularly limited, but is preferably 5 to 20 mm, and more preferably 10 to 15 mm.

[0023] <Bead layer> In the first embodiment, a bead layer 25 is provided outside the portion of the anticorrosion layer 21 formed on the outer surface of the joint 12, and inside a corrosion-resistant layer 27 described later.

[0024] The bead layer 25 is a layer filled with bead-like foam. The bead-like foam refers to an aggregate of particles (beads) made of foamed plastic and having a diameter of about several mm. The diameter of the beads is preferably about 2 to 6 mm, and more preferably about 3 to 5 mm. The foamed plastic may be polystyrene foam (aerated polystyrene). The foamed plastic may be made of polyethylene, polyurethane, polypropylene, or the like, in addition to polystyrene.

[0025] For example, a bead layer 25 can be formed by filling a bag containing a large number of such bead-like foams between the outer surface of the joint 12 and the inner surface of the corrosion-resistant layer 27 (in the case of embodiment 1, outside the portion of the corrosion-resistant layer 21 formed on the surface of the joint 12 and inside the corrosion-resistant layer 27).

[0026] Here, it is preferable to further add sand or the like to the bag containing the foam beads to adjust the buoyancy of the bag containing the foam beads.

[0027] <Waterproof sheet> The corrosion-resistant structure of the present invention may further include a waterproof sheet between the corrosion-resistant layer 21 and the cushion layer 23 or between the corrosion-resistant layer 21 and the bead layer 25. As the waterproof sheet, for example, a conventionally known sheet made of polyethylene can be used.

[0028] <Corrosion-resistant layer> The corrosion-resistant layer 27 is a corrosion-resistant sheet or plate-like structure, is disposed at the outermost position in the corrosion-protective structure 2 of the present invention, and is not particularly limited as long as it is processed into a shape that can be fixed to the outer surface of the steel pipe sheet pile 1. The corrosion-resistant layer 27 may, for example, consist of a semicircular cross-sectional portion that conforms to the outer surface shape of the steel pipe body 11 in the steel pipe sheet pile 1 and a portion that extends linearly from the end of the semicircular cross-sectional portion. Alternatively, as in embodiment 1 shown in FIG. 1 , a flange portion 271 may be formed in the semicircular cross-sectional portion that conforms to the outer surface shape of the steel pipe body 11, and may be connected to the flange portion 271 of another corrosion-resistant layer 27 disposed adjacently by a bolt 273 and a nut 275.

[0029] The corrosion-resistant layer 27 is preferably made of, for example, a corrosion-resistant metal plate. When the corrosion-resistant layer 27 is made of a corrosion-resistant metal plate, the material of the corrosion-resistant metal plate is not particularly limited. Examples of corrosion-resistant metals include titanium, titanium alloys, and stainless steel (e.g., SUS316, SUS316L, SUS317, and SUS317 with Cu, N, or the like added to improve pitting corrosion resistance, etc.), and titanium or a titanium alloy is preferred.

[0030] The thickness of the corrosion-resistant metal plate is not particularly limited, but is preferably 0.3 to 5.0 mm, and more preferably 1.0 to 3.0 mm, because it is lightweight and easy to handle during construction. The corrosion-resistant metal plate may be made by joining two or more plates together.

[0031] The corrosion-resistant layer 27 may be made of fiber-reinforced plastics (FRP) containing glass fiber, carbon fiber, or the like. In this case, the thickness of the corrosion-resistant layer made of FRP is preferably 0.3 to 5.0 mm, and more preferably 2.0 to 3.0 mm.

[0032] <Fixing means> The fixing means 29 is not fixed to the joint 12 but is fixed to the outer surface of the steel pipe body 11 . The fastening means 29 is preferably a bolt and nut. For example, a plurality of bolts are welded to the surface of a fixing plate (such as a steel strip), and the fixing plate is welded to the outer surface of the steel pipe body 11 so that the bolts face outward.The bolts are then passed through the corrosion protection layer 21, cushion layer 23, and corrosion-resistant layer 27 in that order, and the bolts are fastened by screwing nuts onto the outer surface of the corrosion-resistant layer 27.

[0033] The fixing means 29 is preferably installed on the outer surface of the steel pipe body 11, at a position as close as possible to the joint 12. In this case, the corrosion-resistant layer 27, the bead layer 25, and the corrosion-protective layer 21 can be more closely attached to the outer surface of the joint 12 on the outer surface side of the joint 12.

[0034] Specifically, in a cross section perpendicular to the central axis ω of the steel pipe body 11 as shown in Figure 1, the angle θ formed by the line connecting the points indicating the central axes ω of two adjacent steel pipe bodies 11 and the line connecting the points indicating the central axes ω and the location of the fixing means is preferably 20 to 50 degrees, and more preferably 30 to 45 degrees. This is because this allows the corrosion-resistant layer 27, bead layer 25, and corrosion-protective layer 21 to be more closely attached to the outer surface of the joint 12 on the outer surface side.

[0035] [Embodiment 2] Next, another specific embodiment of the corrosion prevention structure of the present invention will be described with reference to FIG. The specific embodiment of the corrosion-resistant structure of the present invention shown in FIG. 2 will hereinafter also be referred to as "embodiment 2."

[0036] 2 is a schematic cross-sectional view of a diaphragm wall 3 formed by the Gyropress method (registered trademark). The diaphragm wall shown in embodiment 2 is a marine structure in which steel pipe bodies 31 are connected via joints 32, and is installed on land L. The diagram also shows a state in which a corrosion prevention structure 2 of the present invention is attached to the sea S side (outside) of the diaphragm wall. The side of an offshore structure where water such as seawater exists is also called the "outside," and the opposite side is called the "inside." In the case of embodiment 2, the side of the sea S facing the land L is the "outside," and the opposite side is the "inside."

[0037] In FIG. 2, the same components as those in the first embodiment described above with reference to FIG. 1 are denoted by the same reference numerals.

[0038] In Figure 2, the continuous wall 3 has a steel pipe body 31 with a circular cross section formed from a long tubular steel material, and a joint 32 arranged so as to be sandwiched between two steel pipe bodies 31. The steel pipe bodies 31 are connected by the joints 32 to form the wall.

[0039] The joint 32 is a steel pipe made of a cylinder with a smaller diameter than the steel pipe body 31. A total of two such steel pipes are arranged on each of the land L side and the sea S side.

[0040] The diaphragm wall 3 of the second embodiment is used to construct a quay structure for a port facility. In such an application, corrosion is likely to progress due to exposure to seawater. Therefore, the corrosion-resistant structure 2 of the present invention can be preferably applied to the diaphragm wall 3.

[0041] In embodiment 2, the corrosion-resistant structure 2 of the present invention includes a corrosion-resistant layer 21 formed on the surface of the continuous wall 3. Also, a cushion layer 23 is provided on the outside of the portion of the corrosion-resistant layer 21 formed on the surface of the steel pipe body 31. Also, a bead layer 25 is provided on the outside of the portion of the corrosion-resistant layer 21 formed on the surface of the joint 32. And, on the outside of the cushion layer 23 and the bead layer 25, a corrosion-resistant layer 27 is provided as the outermost layer. These layers are fixed in close contact with the surface of the continuous wall 3 by fixing means 29 fixed to the surface of the steel pipe body 31 .

[0042] In embodiment 2, the anticorrosion layer 21, cushion layer 23, bead layer 25, corrosion-resistant layer 27 and fixing means 29 may be the same as those in embodiment 1. The same applies to the preferred embodiment. As in the case of the first embodiment, in the second embodiment, a similar waterproof sheet may be further provided between the anticorrosion layer 21 and the cushion layer 23 or between the anticorrosion layer 21 and the bead layer 25.

[0043] [Embodiment 3] Next, another specific embodiment of the corrosion prevention structure of the present invention will be described with reference to FIG. The specific embodiment of the corrosion prevention structure of the present invention shown in FIG. 3 will hereinafter also be referred to as "embodiment 3."

[0044] 3 is a schematic cross-sectional view of a diaphragm wall 4 formed by the Gyropress Method (registered trademark). The diaphragm wall shown in embodiment 3 is a marine structure in which steel pipe bodies 41 are connected via joints 42, and is installed on land L. Unlike embodiment 2, embodiment 3 differs in that the joints 42 are made of isosceles angle steel that plays the role of retaining earth. The figure also shows a state in which a corrosion prevention structure 2 of the present invention is attached to the sea S side (outside). The side of an offshore structure where water such as seawater exists is also called the "outside," and the opposite side is called the "inside." In the case of embodiment 3, the side of the sea S facing the land L is the "outside," and the opposite side is the "inside."

[0045] In FIG. 3, the same components as those in the first embodiment described with reference to FIG. 1 and the second embodiment described with reference to FIG. 2 are denoted by the same reference numerals.

[0046] In Figure 3, the continuous wall 4 has a steel pipe body 41 with a circular cross section formed from a long tubular steel material, and a joint 42 arranged so as to be sandwiched between two steel pipe bodies 41. The wall is formed by connecting the steel pipe bodies 41 with the joint 42. In the third embodiment, a sealant 43 is filled so as to fill the gap between the joint 42 and the steel pipe body 11. As the sealant, for example, an underwater curing epoxy resin sealant can be used.

[0047] The diaphragm wall 4 of the third embodiment is used to construct a quay structure for a port facility. In such an application, corrosion is likely to progress due to exposure to seawater. Therefore, the corrosion-resistant structure 2 of the present invention can be preferably applied to the diaphragm wall 4.

[0048] In embodiment 3, the corrosion-resistant structure 2 of the present invention includes a corrosion-resistant layer 21 formed on the surface of the continuous wall 4. Also, a cushion layer 23 is provided on the outside of the portion of the corrosion-resistant layer 21 formed on the surface of the steel pipe body 41. Also, a bead layer 25 is provided on the outside of the portion of the corrosion-resistant layer 21 formed on the surface of the joint 42. And, on the outside of the cushion layer 23 and the bead layer 25, a corrosion-resistant layer 27 is provided as the outermost layer. These layers are fixed so as to be in close contact with the surface of the continuous wall 4 by fixing means 29 fixed to the surface of the steel pipe body 41 .

[0049] In embodiment 3, the anticorrosion layer 21, cushion layer 23, bead layer 25, corrosion-resistant layer 27 and fixing means 29 may be the same as those in embodiment 1. The same applies to the preferred embodiment. Furthermore, as in the cases of embodiments 1 and 2, in the case of embodiment 3, a similar waterproof sheet may also be provided between the corrosion protection layer 21 and the cushion layer 23, or between the corrosion protection layer 21 and the bead layer 25. [Explanation of symbols]

[0050] 1 Steel pipe sheet pile 11, 31, 41 Steel pipe body 12, 32, 42 fittings 2. Corrosion-resistant structure of the present invention 21 Anti-corrosion layer 23 Cushion layer 25 bead layers 27 Corrosion-resistant layer 271 Flange 273 volts 275 Nut 29 Fixing means 3, 4 consecutive walls

Claims

1. A corrosion prevention structure including at least a corrosion prevention layer and a corrosion-resistant layer disposed on a surface of a wall where adjacent steel pipe bodies are connected via joints, and a fixing means for fixing them to the wall, a bead layer formed by filling a bead-shaped foam between the outer surface of the joint and the inner surface of the corrosion-resistant layer; The fixing means is not fixed to the joint but is fixed to the outer surface of the steel pipe body, The fixing means includes a fixing plate fixed to the steel pipe body, a bolt fixed upright to the fixing plate, and a nut screwed onto the bolt, and the fixing plate is welded to the outer surface of the steel pipe body so that the bolt axis faces the center of the steel pipe body, A corrosion prevention structure in which the bolt is passed through the corrosion protection layer and the corrosion resistant layer, and then screwed onto the nut to be fixed to the outer surface of the steel pipe body.

2. In a cross section perpendicular to the central axis of the steel pipe body, The corrosion-resistant structure according to claim 1, wherein the angle formed by the line connecting the points indicating the central axes of two adjacent steel pipe bodies and the line connecting the points indicating the central axes and the position of the fixing means is 20 to 50 degrees.

3. The corrosion-resistant structure according to claim 1 or 2, further comprising a cushion layer between the corrosion-resistant layer and the corrosion-protective layer.

4. The corrosion-resistant structure according to claim 3 , further comprising a waterproof sheet between the corrosion-resistant layer and the cushion layer.

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