Synthetic Box Culvert

Abstract

The present invention provides a composite box culvert capable of improving shear strength. 【Solution means】 The composite box culvert according to the present invention includes a cylindrical concrete structure formed around an axis, and an outer shell steel plate formed to cover the outer peripheral surface of the concrete structure, and is a composite box culvert in which a cross section perpendicular to the axis is rectangular, and the outer shell steel plate includes an outer peripheral covering portion that covers the outer peripheral surface of the concrete structure over the entire circumference, and a plurality of protruding portions that protrude from the inner peripheral surface of the outer peripheral covering portion and are embedded in the concrete structure and extend from one end side to the other end side of the concrete structure along the axial direction.

Description

Technical Field

[0001] The present invention relates to a synthetic box culvert.

Background Art

[0002] A synthetic box culvert is a tubular structure with a rectangular cross-section. For example, by being buried underground, it constitutes pipelines such as electric wires, gas pipes, water supply pipes, sewer pipes, and communication wiring. Since a synthetic box culvert exhibits high flexural strength, it is known that it is difficult to be damaged by earth pressure even when buried deep underground.

[0003] By the way, synthetic box culverts are required to exhibit excellent resistance to shear generated during earthquakes. Conventionally, in order to improve the shear resistance of synthetic box culverts, for example, shear reinforcement bars such as Jebel steel bars, loop-shaped bars, and star-lap bars have been installed (Patent Documents 1, 2, etc.).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, since the shear reinforcement bars need to be joined so as to connect the inner and outer iron members (such as steel bars and steel plates) one by one, the installation work is very complicated. Therefore, in order to improve the shear resistance of synthetic box culverts, the development of new technologies is required.

[0006] In view of such a situation, an object of the present invention is to provide a composite box culvert capable of improving shear strength.

Means for Solving the Problems

[0007] The composite box culvert according to the present invention includes a cylindrical concrete structure formed around an axis, and an outer shell steel plate formed so as to cover the outer peripheral surface of the concrete structure, and is a composite box culvert in which a cross section perpendicular to the axis is rectangular. The outer shell steel plate has an outer peripheral covering portion that covers the entire outer peripheral surface of the concrete structure, and a plurality of protruding portions that protrude from the inner peripheral surface of the outer peripheral covering portion and are embedded in the concrete structure and extend from one end side to the other end side of the concrete structure along the axial direction.

[0008] The composite box culvert can improve shear strength by having a plurality of the protruding portions on the outer shell steel plate.

[0009] In the composite box culvert according to the present invention, the protruding portion may be constituted by a plate-like member, and a surface in the thickness direction of the plate-like member may be in contact with the outer peripheral covering portion.

[0010] With such a configuration, the composite box culvert can increase the area of contact between the protruding portion and the concrete structure, and thus can improve the adhesion of the concrete structure to the protruding portion.

[0011] In the composite box culvert according to the present invention, on at least one of the four surfaces constituting the outer peripheral covering portion, the protruding portions may be arranged at substantially equal intervals.

[0012] With such a configuration, the composite box culvert can further improve shear strength.

[0013] In the composite box culvert according to the present invention, the ratio of the length of the protruding portion in the protruding direction to the thickness of the concrete structure may be 0.03 or more and 1 or less.

[0014] With such a configuration, the composite box culvert can further improve the shear strength.

[0015] In the composite box culvert according to the present invention, the ratio of the thickness of the protruding portion to the thickness of the outer peripheral covering portion may be 0.25 or more and 4.00 or less.

[0016] With such a configuration, the composite box culvert can further improve the shear strength.

[0017] In the composite box culvert according to the present invention, in the concrete structure, main reinforcing bars extending along a direction perpendicular to the axis and arranged in a plurality around the axis are embedded, and the main reinforcing bars may be joined to the protruding portion.

[0018] With such a configuration, the composite box culvert can further improve the shear strength.

Effects of the Invention

[0019] As described above, according to the present invention, it is possible to provide a composite box culvert capable of improving the shear strength.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0021] Hereinafter, the composite box culvert 1 according to the embodiment of the present invention will be described with reference to FIGS. 1 to 3. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated. FIG. 1 is a perspective view of the composite box culvert 1 according to the present embodiment. FIG. 2 is a cross-sectional view in a direction perpendicular to the axis L of the composite box culvert 1 shown in FIG. 1. FIG. 3 is a cross-sectional view taken along line III-III of the composite box culvert 1 shown in FIG. 2.

[0022] The composite box culvert 1 according to the present embodiment includes a cylindrical concrete structure 2 formed around an axis L extending in one direction, and an outer shell steel plate 3 formed so as to cover the outer peripheral surface of the concrete structure 2. The composite box culvert 1 forms an internal space by the inner peripheral surface of the composite box culvert 1, and the internal space is configured to be able to accommodate electric wires, gas pipes, water supply pipes, sewer pipes, communication wirings, etc.

[0023] The composite box culvert 1 has a rectangular cross-section perpendicular to the axis L, and more specifically, a substantially square cross-section. The size of the composite box culvert 1 is not particularly limited. The length of the composite box culvert 1 along the axis L can be, for example, 300 mm or more and 2000 mm or less. The distance between the opposing outer peripheral surfaces of the cross-section perpendicular to the axis L of the composite box culvert 1 can be, for example, 900 mm or more and 3600 mm or less, and the distance between the opposing inner peripheral surfaces of the cross-section perpendicular to the axis L can be, for example, 600 mm or more and 3100 mm or less. The composite box culvert 1 has an R shape with a predetermined curvature at the corners of the outer peripheral surface and the inner peripheral surface in a cross-section perpendicular to the axis L.

[0024] The concrete constituting the concrete structure 2 may be, for example, a composition containing cement, coarse aggregate, and fine aggregate kneaded with water. Further, the composition may contain blast furnace slag fine powder, fly ash, etc. instead of cement. The cement, coarse aggregate, and fine aggregate are not particularly limited, and conventionally known ones can be used. Further, the cement composition may contain other materials such as fiber materials, admixtures, and admixtures.

[0025] The cement is not particularly limited, and for example, various cements available on the market can be used. Specifically, one selected from the group consisting of various Portland cements such as ordinary Portland cement and early-strength Portland cement, blast furnace cement, silica cement, and various blended cements with fly ash cement, white Portland cement, alumina cement, and ultra-high early-strength cements such as calcium aluminate-based, calcium sulfoaluminate-based, and calcium fluoroaluminate-based cements may be used, or a plurality may be mixed and used.

[0026] As the coarse aggregate, those having a size such that 85% by mass or more does not pass through a 5 mm sieve can be used. Specifically, examples of the coarse aggregate include crushed sandstone, cobblestones (river cobblestones), natural lightweight coarse aggregate (perlite, pumice stone, etc.), by-product lightweight coarse aggregate, artificial lightweight coarse aggregate, recycled aggregate, and the like. The content of the coarse aggregate is not particularly limited, and for example, it may be 100% by mass or more and 300% by mass or less, or 100% by mass or more and 200% by mass or less, based on the cement.

[0027] Fine aggregate can pass through all 10 mm sieves and 85 mass% or more of it can pass through 5 mm sieves. Specifically, examples of fine aggregate include natural sand such as mountain sand, river sand, land sand, and sea sand, and crushed sand (more specifically, lime crushed sand, etc.) formed by artificially crushing sandstone, limestone, etc. The content of fine aggregate is not particularly limited. For example, it may be 100 mass% or more and 300 mass% or less, or 150 mass% or more and 250 mass% or less, based on the cement.

[0028] Note that the sizes of the above coarse aggregate and fine aggregate are measured by the aggregate sieving test method according to JIS A 1102, and represent the test sieves of JIS Z 8801-1.

[0029] In addition, other materials included in the cement composition are not particularly limited. For example, they include fiber materials (such as glass fiber, steel fiber, vinylon fiber, aramid fiber, polypropylene fiber, carbon fiber, etc.), admixtures (such as blast furnace slag, fly ash, silica fume, expansive agent, etc.), and admixtures (such as water reducing agent, thickening agent, defoaming agent, etc.).

[0030] Water is not particularly limited, and known water that can be used as mixing water can be used. Also, the water may contain, for example, admixtures such as water reducing agents used when kneading mortar or concrete, polymer dispersion liquids, shrinkage reducing agents, setting regulators, etc.

[0031] The thickness of the concrete structure 2 is not particularly limited. When the size of the synthetic box culvert 1 is 3600 mm, the thickness of the concrete structure 2 may be, for example, 220 mm or more and 400 mm or less, or 240 mm or more and 300 mm or less. When the size of the synthetic box culvert 1 is 900 mm, the thickness of the concrete structure 2 may be, for example, 70 mm or more and 200 mm or less, or 130 mm or more and 150 mm or less.

[0032] The outer shell steel plate 3 has an outer peripheral covering portion 31 that covers the outer peripheral surface of the concrete structure 2 over the entire circumference, and a plurality of protruding portions 32 that protrude from the inner peripheral surface of the outer peripheral covering portion 31 and are embedded in the concrete structure 2 and extend from one end side to the other end side of the concrete structure 2 along the axial direction L.

[0033] The outer peripheral covering portion 31 is composed of four surfaces. Specifically, it is composed of an upper surface 31a, a bottom surface 31b, and two side surfaces 31c, 31d. On each surface, eight protruding portions 32 are arranged at substantially equal intervals. The interval at which the protruding portions 32 are arranged is not particularly limited. When the size of the composite box culvert 1 is 3600 mm, the interval at which the protruding portions 32 are arranged may be, for example, 150 mm or more and 450 mm or less, or 200 mm or more and 350 mm or less. When the size of the composite box culvert 1 is 900 mm, the interval at which the protruding portions 32 are arranged may be, for example, 150 mm or more and 350 mm or less, or 200 mm or more and 250 mm or less. Note that the interval at which the protruding portions 32 are arranged is the distance between the centers in the thickness direction of the protruding portions 32. The outer peripheral covering portion 31 and the protruding portions 32 may be integrally formed, or may be formed separately and then joined.

[0034] The entire outer peripheral covering portion 31 is formed using a metal plate. The thickness of the outer peripheral covering portion 31 is not particularly limited. When the size of the composite box culvert 1 is 3600 mm, the thickness of the outer peripheral covering portion 31 may be, for example, 6.0 mm or more and 22 mm or less, or 9.0 mm or more and 19 mm or less. When the size of the composite box culvert 1 is 900 mm, the thickness of the outer peripheral covering portion 31 may be, for example, 4.5 mm or more and 22 mm or less, or 6.0 mm or more and 16 mm or less. Also, the metal constituting the outer peripheral covering portion 31 is not particularly limited, and examples include JIS G 3101 "Hot-Rolled Steel Sheets for General Structure", JIS G 3106 "Hot-Rolled Steel Sheets for Welded Steel Structures", JIS G 4305 "Cold-Rolled Stainless Steel Sheets and Strips", or steel sheets having mechanical properties equivalent to these standard values.

[0035] The rib portion 32 is composed of a plate-shaped member, and the surface in the thickness direction of the plate-shaped member is in contact with the outer peripheral covering portion 31. The thickness and the length in the protruding direction of the rib portion 32 are not particularly limited. When the size of the composite box culvert 1 is 3600 mm, the thickness of the rib portion 32 may be, for example, 6.0 mm or more and 22 mm or less, or may be 9.0 mm or more and 19 mm or less. When the size of the composite box culvert 1 is 900 mm, the thickness of the rib portion 32 may be, for example, 4.5 mm or more and 22 mm or less, or may be 6.0 mm or more and 16 mm or less. Further, when the size of the composite box culvert 1 is 3600 mm, the length of the rib portion 32 in the protruding direction may be, for example, 150 mm or more and 350 mm or less, or may be 200 mm or more and 300 mm or less. When the size of the composite box culvert 1 is 900 mm, the length of the rib portion 32 in the protruding direction may be, for example, 50 mm or more and 150 mm or less, or may be 70 mm or more and 100 mm or less.

[0036] The entire rib portion 32 is formed using a metal plate. The metal constituting the rib portion 32 is not particularly limited, and the same metal as that of the outer peripheral covering portion 31 can be used.

[0037] From the viewpoint of improving the shear strength, the ratio of the length of the rib portion 32 in the protruding direction to the thickness of the concrete structure 2 is preferably 0.03 or more and 1 or less, and more preferably 0.5 or more and 0.8 or less.

[0038] From the viewpoint of improving the shear strength, the ratio of the thickness of the rib portion 32 to the thickness of the outer peripheral covering portion 31 is preferably 0.25 or more and 4.00 or less, and more preferably 1.00 or more and 4.00 or less.

[0039] The synthetic box culvert 1 has a reduced-diameter portion 3' where the outer peripheral surface of the outer shell steel plate 3 is reduced in diameter at one end side in the direction of the axis L. Further, the synthetic box culvert 1 has a tubular protruding portion 33 protruding in the direction in which the axis L extends from the end of the outer peripheral covering portion 31 at the other end side in the direction of the axis L. The synthetic box culvert 1 can form a pipeline by inserting the reduced-diameter portion 3' at one end side of one synthetic box culvert 1 into the tubular protruding portion 33 at the other end side of another synthetic box culvert 1 along the axis L.

[0040] A hole 4 penetrating the outer peripheral covering portion 31 and the concrete structure 2 is formed in the synthetic box culvert 1. The holes 4 are formed one by one with respect to the four surfaces constituting the outer peripheral covering portion 31. The hole 4 may be used, for example, as an injection hole for injecting a lubricant or a backfill injection material, an exhaust hole for discharging air, or the like.

[0041] The synthetic box culvert 1 according to the present embodiment can improve the shear strength because the outer shell steel plate 3 has a plurality of protruding ridges 32.

[0042] In the synthetic box culvert 1 according to the present embodiment, since the protruding ridge 32 is constituted by a plate-like member and the surface in the thickness direction of the plate-like member is in contact with the outer peripheral covering portion 31, the area of contact between the protruding ridge 32 and the concrete structure 2 can be increased, so that the adhesion of the concrete structure 2 to the protruding ridge 32 can be improved.

[0043] In the synthetic box culvert 1 according to the present embodiment, on at least one of the four surfaces constituting the outer peripheral covering portion 31, the protruding ridges 32 are arranged at substantially equal intervals, so that the shear strength can be further improved.

[0044] In the synthetic box culvert 1 according to the present embodiment, the ratio of the length of the protruding ridge 32 in the protruding direction to the thickness of the concrete structure 2 is 0.03 or more and 1 or less, so that the shear strength can be further improved.

[0045] For the composite box culvert 1 according to this embodiment, the ratio of the thickness of the rib portion 32 to the thickness of the outer peripheral covering portion 31 is 0.25 or more and 4.00 or less, so that the shear strength can be further improved.

[0046] As described above, the embodiments of the present invention have been described. However, the composite box culvert according to the present invention is not limited to this embodiment, and various modifications can be made without departing from the gist of the present invention. Further, the composite box culvert according to the present invention is not limited by the above-described effects.

[0047] For example, the cross section perpendicular to the axis L of the composite box culvert 1 according to the above embodiment was substantially square. However, the composite box culvert according to the present invention is not limited to this configuration, and the cross section perpendicular to the axis L may be a rectangular shape in which the width direction or the height direction is long.

[0048] In the cross section perpendicular to the axis L of the composite box culvert 1 according to the above embodiment, the corners of the outer peripheral surface and the inner peripheral surface have an R shape. However, the composite box culvert according to the present invention is not limited to this configuration, and in the cross section perpendicular to the axis L, the corners of the outer peripheral surface and the inner peripheral surface may have a right angle shape.

[0049] The rib portion 32 of the composite box culvert 1 according to the above embodiment is constituted by a plate-like member. However, the composite box culvert according to the present invention is not limited to this configuration, and the rib portion 32 may be constituted by flat steel, H-shaped steel, C-shaped steel, L-shaped steel, or the like. Further, from the viewpoint of improving the adhesion to the concrete structure 2, a plurality of holes penetrating in the thickness direction may be formed in the rib portion 32.

[0050] In the composite box culvert 1 according to the above-described embodiment, on the four surfaces constituting the outer peripheral covering portion 31, eight ridge portions 32 are arranged at substantially equal intervals respectively. However, the composite box culvert according to the present invention is not limited to such a configuration. In at least one of the four surfaces constituting the outer peripheral covering portion 31, the ridge portions 32 may be arranged at substantially equal intervals, or on all the surfaces, the ridge portions 32 may be arranged at unequal intervals. Further, four or more and 15 or less ridge portions 32 may be arranged on one surface constituting the outer peripheral covering portion 31. The number of ridge portions 32 arranged on one surface constituting the outer peripheral covering portion 31 does not have to be equal on all the surfaces.

[0051] In the composite box culvert 1 according to the above-described embodiment, holes 4 are formed one by one in the four surfaces constituting the outer peripheral covering portion 31. However, the composite box culvert according to the present invention is not limited to such a configuration, and the position and number of the holes 4 can be appropriately selected according to the usage mode. As another aspect, the hole 4 may be used, for example, as a sling hole for hooking a sling during transportation, a sling insert for attaching a sling during transportation, a waterstop injection hole for injecting a waterstop agent, or the like. Further, the composite box culvert according to the present invention may not have the holes 4 formed therein.

[0052] The composite box culvert 1 according to the above-described embodiment does not include reinforcing bars. However, the composite box culvert according to the present invention is not limited to such a configuration, and in the concrete structure 2, main reinforcing bars extending along a direction perpendicular to the axis L and arranged in a plurality around the axis L may be embedded, and the main reinforcing bars may be joined to the ridge portions 32. With such a configuration, the shear strength of the composite box culvert can be further improved. Further, in the concrete structure 2, distribution reinforcing bars extending along the axis L and arranged in a plurality around the axis L may be embedded. The reinforcing bars are not particularly limited, and those generally used in the production of reinforced concrete can be used.

[0053] The present disclosure includes the following aspects. [1] A composite box culvert comprising a cylindrical concrete structure formed around an axis and an outer shell steel plate formed to cover the outer peripheral surface of the concrete structure, wherein a cross section perpendicular to the axis is rectangular. The outer shell steel plate has an outer peripheral covering portion that covers the entire outer peripheral surface of the concrete structure, and a plurality of protruding portions that protrude from the inner peripheral surface of the outer peripheral covering portion and are embedded in the concrete structure and extend from one end side to the other end side of the concrete structure along the axial direction. [2] The protruding portion is composed of a plate-like member. The composite box culvert according to [1], wherein a surface in the thickness direction of the plate-like member is in contact with the outer peripheral covering portion. [3] The composite box culvert according to [1] or [2], wherein the protruding portions are arranged at substantially equal intervals on at least one of the four surfaces constituting the outer peripheral covering portion. [4] The composite box culvert according to any one of [1] to [3], wherein a ratio of a length in a protruding direction of the protruding portion to a thickness of the concrete structure is 0.03 or more and 1 or less. [5] The composite box culvert according to any one of [2] to [4], wherein a ratio of a thickness of the protruding portion to a thickness of the outer peripheral covering portion is 0.25 or more and 4.00 or less. [6] Main reinforcing bars are embedded in the concrete structure so as to extend in a direction perpendicular to the axis and are arranged in a plurality around the axis. The composite box culvert according to any one of [1] to [5], wherein the main reinforcing bars are joined to the protruding portions.

Explanation of reference numerals

[0054] 1 Box culvert 2 Concrete structure 3 Outer shell steel plate 31 Outer peripheral covering portion 32 Protruding portion L Axis

Claims

1. A composite box culvert comprising a cylindrical concrete structure formed around an axis and an outer shell steel plate formed to cover the outer peripheral surface of the concrete structure, wherein a cross-section perpendicular to the axis is rectangular, the outer shell steel plate has an outer peripheral covering portion that covers the entire outer peripheral surface of the concrete structure and a plurality of protruding portions that protrude from the inner peripheral surface of the outer peripheral covering portion and are embedded in the concrete structure and extend from one end side to the other end side of the concrete structure along the axial direction, the outer peripheral covering portion is composed of four surfaces, and on each surface, the protruding portions are arranged at substantially equal intervals. Composite box culvert.

2. The protruding portion is constituted by a plate-like member, The composite box culvert according to claim 1, wherein a surface in the thickness direction of the plate-like member is in contact with the outer peripheral covering portion.

3. The ratio of the length of the protruding portion in the protruding direction to the thickness of the concrete structure is 0.03 or more and 1 or less. The composite box culvert according to claim 1 or 2.

4. The ratio of the thickness of the protruding portion to the thickness of the outer peripheral covering portion is 0.25 or more and 4.00 or less. The composite box culvert according to claim 2.

5. In the concrete structure, main reinforcement bars are embedded that extend along a direction perpendicular to the axis and are arranged in a plurality around the axis, The composite box culvert according to claim 1 or 2, wherein the main reinforcement bars are joined to the protruding portions.

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