Box culvert and its construction method

Abstract

To improve workability in constructing box culvert when using precast members, rationalize member design by distributing load in the longitudinal direction, and improve rigidity against bending in the longitudinal direction.SOLUTION: A box culvert includes a top section forming a ceiling surface and a side wall section forming a side surface. The top section includes a plurality of rows of precast members arranged continuously in the length direction of the box culvert, and a cast-in-place concrete beam extending along the length of the box culvert between adjacent rows of precast members. Inside the beam, reinforcing bars protruding from the precast members in one row and reinforcing bars protruding from the precast members in the other row are connected to each other. A main reinforcing bar extending in the length direction of the box culvert is buried inside the beam.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a box culvert and a method for constructing the same. [Background technology]

[0002] In recent years, construction of new trunk roads has been shifting from plains to mountainous areas, and the number of new roads passing through steep mountainous areas is increasing. In road construction in mountainous areas, the proportion of tunnels and bridges is increasing, leading to an increase in high embankments, and the construction of culvert structures (also simply called culverts) that cross these embankments is increasing. One example of a culvert structure is the box culvert, which has a roughly rectangular cross section. Culvert structures are constructed using various construction methods, for example, by combining precast concrete members and cast-in-place concrete.

[0003] For example, Patent Document 1 discloses a method for constructing a large box culvert. In Patent Document 1, a large box culvert is constructed by stacking T-shaped precast blocks on a precast or cast-in-place deck to construct side walls, and erecting a precast top plate on the top of the side walls. At that time, a precast support block is superimposed to integrate the side walls and the precast top plate.

[0004] For example, Patent Document 2 discloses a construction technique for a split-type rigid culvert. Patent Document 2 discloses a structure having a top plate formed by connecting two or more top plate unit blocks. Between the two or more top plate unit blocks, a joint structure is used in which mechanical joints are covered with concrete filling parts. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-229412 [Patent Document 2] JP 2022-34412 A Summary of the Invention [Problem to be solved by the invention]

[0006] The large-scale box culvert described in Patent Document 1 is constructed so that concrete is poured into the precast support block when erecting the precast top plate at the top of the side wall. The precast support block with the concrete poured into it is located at the top end of the culvert's side wall, and there is a risk that the rigidity of the culvert's ceiling surface is insufficient. Specifically, the rigidity of the culvert against bending in the longitudinal direction is insufficient, and there is room for further improvement.

[0007] Furthermore, in the split rigid culvert described in Patent Document 2, the top plate members are split (top plate unit blocks) due to the constraints imposed on manufacturing, transportation, and construction as the culverts become larger. In this configuration, the left and right top plate unit blocks and the middle top plate unit block are integrated by covering them with concrete filling sections. However, while Patent Document 2 describes that the top plate is split in the width direction of the culvert and integrated, it does not describe the case where the top plate is split in the length direction of the culvert. As a result, the rigidity of the culvert against bending in the longitudinal direction is insufficient, and there is room for further improvement.

[0008] Furthermore, in the structures described in Patent Documents 1 and 2, when a load is applied locally to the divided top plate unit blocks, or when a load is concentrated near the center of the top plate, the load (dead load or live load) is not distributed, and there is a risk that the rigidity of the culvert will not be sufficiently guaranteed. Furthermore, when trying to ensure the rigidity of the culvert, it is necessary to increase the thickness of the members, which raises concerns about the increase in the amount of concrete used and costs.

[0009] In recent years, when constructing culvert structures, so-called precast concrete members (also simply called precast members) are sometimes used, in which members that are prefabricated in a factory or the like are transported to the site and assembled. Conventionally, when constructing a top plate using precast members, the method used was to first connect the divided top plate members on an assembly frame, and then hoist and install the integrated top plate. In this case, there were problems such as the need to secure a yard for constructing the assembly frame, increased costs, and the need for a large crane for lifting.

[0010] In consideration of the above circumstances, the object of the present invention is to provide a box culvert and a construction method thereof that improves workability when using precast members in the construction of a box culvert, and that can rationalize member design by distributing load in the longitudinal direction, and improve rigidity against bending in the longitudinal direction. [Means for solving the problem]

[0011] In order to achieve the above object, according to the present invention, there is provided a box culvert having a top plate portion constituting a ceiling surface and a side wall portion constituting a side surface, the top plate portion including a plurality of rows of precast members arranged continuously in the longitudinal direction of the box culvert, and a beam portion made of cast-in-place concrete extending in the longitudinal direction of the box culvert between adjacent rows of the precast members, the inside of the beam portion being connected to the reinforcing bars protruding from the precast members in one row and the reinforcing bars protruding from the precast members in the other row, and the inside of the beam portion being embedded with main reinforcing bars extending in the longitudinal direction of the box culvert. The beam and the main reinforcing bars therein are constructed across a plurality of the precast members adjacent in the longitudinal direction of the box culvert. A box culvert is provided.

[0012] The side wall portion may be constructed by arranging a plurality of precast side wall members, each having the same length as the precast member constituting the top plate portion in the longitudinal direction of the box culvert, in succession in the longitudinal direction of the box culvert.

[0013] The multiple rows of precast members may be composed of three rows, the precast members in the first and second rows are corner members having flat portions extending in the width direction of the box culvert, and the corner members are respectively arranged on a pair of the side wall portions, and the precast member in the third row is an intermediate member having a flat portion extending in the width direction of the box culvert and is installed between the precast members in the first row and the precast members in the second row, and beam portions may be provided between the precast members in the first row and the precast members in the third row, and between the precast members in the second row and the precast members in the third row, respectively.

[0014] The precast members in the third row may further include legs extending downwardly from the flat plate portion, and the legs may form part or all of the height of the intermediate wall of the box culvert.

[0015] Further, according to the present invention, there is provided a method for constructing a box culvert having a top plate portion constituting a ceiling surface and side wall portions constituting side surfaces, comprising a corner portion construction step of constructing a corner portion by continuously arranging precast corner members having flat plate portions extending in the width direction of the box culvert on a pair of side wall portions in the length direction of the box culvert; a top plate center portion construction step of continuously arranging precast intermediate members having flat plate portions extending in the width direction of the box culvert between the corner portions constructed on the pair of side wall portions in the length direction of the box culvert to construct a top plate center portion; and a top plate center portion construction step of constructing a top plate center portion by continuously arranging precast intermediate members having flat plate portions extending in the width direction of the box culvert in the length direction of the box culvert along a gap provided between the corner portion and the top plate center portion. Across the adjacent intermediate members and a beam section construction process for constructing an extending beam section, in which reinforcing bars protruding from the corner member and the intermediate member in a direction facing each other are connected to each other in the gap section, and further, a main reinforcing bar extending in the longitudinal direction of the box culvert is connected to the corner member and the intermediate member in a direction facing each other in the gap section. Across a plurality of the intermediate members adjacent in the longitudinal direction of the box culvert A method for constructing a box culvert is provided, which comprises the steps of: placing the box culverts in place; pouring in-situ concrete into the gap to construct the beam portion; and forming the top plate portion from the corner portion, the central portion of the top plate, and the beam portion.

[0016] According to the present invention, there is provided a method for constructing a box culvert having a top plate portion constituting a ceiling surface and side wall portions constituting side surfaces, the method comprising the steps of: constructing a corner portion by continuously arranging precast corner members having flat plate portions extending in the width direction of the box culvert on a pair of the side wall portions in the longitudinal direction of the box culvert; and constructing a corner portion between the pair of adjacent flat plate portions between the corner portions constructed on the pair of the side wall portions. To Along the provided gap, in the length direction of the box culvert Across the adjacent corner members and a beam section construction process for constructing an extending beam section, in which reinforcing bars protruding in the direction facing each other from the pair of corner members are connected to each other in the gap section, and further, a main reinforcing bar extending in the longitudinal direction of the box culvert is connected to the main reinforcing bar. Across a plurality of the corner members adjacent in the longitudinal direction of the box culvert A method for constructing a box culvert is provided, which is characterized in that after the beams are placed, in-situ concrete is poured into the gap to construct the beams, and the top plate is formed by the corner portions and the beams. Effect of the Invention

[0017] According to the present invention, it is possible to improve the workability when using precast members in the construction of box culverts, and also to rationalize the member design by distributing the load in the longitudinal direction, and to improve the rigidity against bending in the longitudinal direction.

[0018] The above effects are not necessarily limiting, and any of the effects shown in this specification or other effects that can be understood from this specification may be achieved in addition to or instead of the above effects. [Brief description of the drawings]

[0019] [Figure 1] 1 is a schematic explanatory diagram of a box culvert according to an embodiment of the present invention. FIG. [Diagram 2] FIG. 1 is a schematic diagram illustrating a method for constructing a box culvert. [Diagram 3] FIG. 1 is a schematic diagram illustrating a method for constructing a box culvert. [Figure 4] FIG. 1 is a schematic diagram illustrating a method for constructing a box culvert. [Diagram 5] FIG. 1 is a schematic diagram illustrating a method for constructing a box culvert. [Figure 6] FIG. 1 is a schematic diagram illustrating a method for constructing a box culvert. [Figure 7] FIG. 1 is a schematic diagram illustrating a method for constructing a box culvert. [Figure 8] FIG. 1 is a schematic diagram illustrating a method for constructing a box culvert. [Figure 9] FIG. 2 is a schematic explanatory diagram showing the reinforcing bar arrangement configuration embedded in the beam portion of a box culvert. [Figure 10] FIG. 10 is a partially enlarged view of the reinforcement configuration shown in FIG. [Figure 11] FIG. 1 is a schematic explanatory diagram of a method for constructing a box culvert according to a first alternative embodiment. [Figure 12] FIG. 1 is a schematic explanatory diagram of a method for constructing a box culvert according to a first alternative embodiment. [Figure 13] FIG. 1 is a schematic explanatory diagram of a method for constructing a box culvert according to a first alternative embodiment. [Figure 14] FIG. 1 is a schematic explanatory diagram of a method for constructing a box culvert according to a first alternative embodiment. [Figure 15] FIG. 1 is a schematic explanatory diagram of a method for constructing a box culvert according to a first alternative embodiment. [Figure 16] FIG. 1 is a schematic explanatory diagram of a method for constructing a box culvert according to a first alternative embodiment. [Figure 17] FIG. 1 is a schematic explanatory diagram of a method for constructing a box culvert according to a first alternative embodiment. [Figure 18] FIG. 11 is a schematic explanatory diagram of a method for constructing a box culvert according to a second alternative embodiment. [Figure 19] FIG. 11 is a schematic explanatory diagram of a method for constructing a box culvert according to a second alternative embodiment. [Figure 20] FIG. 11 is a schematic explanatory diagram of a method for constructing a box culvert according to a second alternative embodiment. [Figure 21] FIG. 11 is a schematic explanatory diagram of a method for constructing a box culvert according to a second alternative embodiment. [Figure 22] FIG. 11 is a schematic explanatory diagram of a method for constructing a box culvert according to a second alternative embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this specification and the drawings, components having substantially the same functional configuration may be given the same reference numerals to avoid repetitive explanation. In this embodiment, for the purpose of explanation, some illustrations of the reinforcing bar structure and reinforcing bar arrangement may be omitted, or reinforcing bars inside the members may be illustrated.

[0021] <Box culvert configuration> Fig. 1 is a schematic explanatory diagram of a box culvert 1 according to an embodiment of the present invention. The box culvert 1 shown in Fig. 1 is a rectangular culvert-shaped hollow structure installed at the entrance of a tunnel or the like provided for, for example, a main road or a railway (not shown), and a path (not shown) is laid inside the box culvert for passing through, for example, automobiles, railway vehicles, etc. In the following description, the direction in which the internal space of the box culvert 1 extends is defined as the length direction, the direction parallel to the installation surface of the box culvert 1 and perpendicular to the length direction is defined as the width direction, and the vertical direction when the box culvert 1 is installed is defined as the height direction.

[0022] As shown in Fig. 1, the box culvert 1 includes a bottom plate portion 3 laid on the ground, a side wall portion 5 constructed vertically to the ground, and a top plate portion 10 constructed approximately parallel to the ground on the upper part of the side wall portion 5. The top plate portion 10 is placed on the upper part of the side wall portion 5 and is provided so as to form the ceiling surface of the box culvert 1. In addition, a bottom plate portion 3 is provided which is parallel to the top plate portion 10 and forms at least a part of the bottom surface located at the lower part of the box culvert 1.

[0023] In the configuration according to this embodiment, the side wall portion 5 is composed of a pair of left and right precast side wall members (hereinafter also simply referred to as side wall members) 5a, 5b arranged continuously in the longitudinal direction of the box culvert 1. Note that the side wall members 5a, 5b may include bottom surface portions 6a, 6b that form part of the bottom surface of the box culvert 1 at their lower ends, as shown in FIG.

[0024] The top plate portion 10 also includes multiple rows of precast members arranged continuously in the longitudinal direction of the box culvert 1. That is, the top plate portion 10 includes a pair of precast corner members 12a, 12b located at both ends in the width direction, and a precast intermediate member 15 located between the corner members 12a and 12b. That is, the corner members 12a and 12b constitute the first and second rows of precast members consisting of three rows in the width direction, and the intermediate member 15 constitutes the third row of precast members.

[0025] The corner members 12a, 12b have the same length as the side wall members 5a, 5b in the longitudinal direction of the box culvert 1, and are arranged on the side wall members 5a, 5b. The corner members 12a, 12b have flat plate portions 13a, 13b extending in the width direction of the box culvert 1, and the intermediate member 15 also has a similar flat plate portion 16.

[0026] The top plate portion 10 also includes beam portions 20a and 20b between the corner member 12a and the intermediate member 15, and between the corner member 12b and the intermediate member 15. The beam portions 20a and 20b extend in the longitudinal direction of the box culvert 1 and are made of, for example, cast-in-place concrete. As described later with reference to Figs. 9 and 10, the beam portions 20a and 20b have a plurality of reinforcing bars embedded therein and function to connect the corner member 12a and the intermediate member 15, and the corner member 12b and the intermediate member 15 in adjacent rows in the width direction of the box culvert 1. Furthermore, the beam portions 20a and 20b also have a function to connect the plurality of precast members (here, the corner members 12a, 12b and the intermediate member 15) arranged continuously in the longitudinal direction of the box culvert 1 to each other, thereby distributing the load.

[0027] <How to build a box culvert> Here, a method for constructing the box culvert 1 according to this embodiment will be described. Figures 2 to 8 are schematic diagrams for explaining the method for constructing the box culvert 1, and the construction process is shown in the order of Figures 2 to 8. Note that the configuration of the reinforcing bars shown in Figures 2 to 8 is one example, and the arrangement, number, etc. of these bars can be designed arbitrarily.

[0028] As shown in Fig. 2, first, a pair of left and right precast side wall members 5a, 5b are hung and installed by a crane or the like (not shown). These side wall members 5a, 5b are installed adjacent to each other in the longitudinal direction of the box culvert 1 as shown in the figure. In this way, a pair of left and right side wall portions 5 consisting of the multiple side wall members 5a, 5b are formed.

[0029] The side wall members 5a, 5b are precast members and may have a plurality of reinforcing bars 31 protruding from their upper ends and a plurality of reinforcing bars 32 protruding toward the inside of the box culvert 1 from the bottom portions 6a, 6b at their lower ends.

[0030] Next, as shown in FIG. 3, a support 40 is installed on the inside of the side wall 5. Here, the support 40 is installed at two locations in total near the inside of the pair of side wall 5. Then, as shown in FIG. 4, corner members 12a and 12b are installed on the upper ends of the side wall members 5a and 5b constituting the side wall 5 on the pair of left and right side wall 5 (corner construction process). At this time, the corner members 12a and 12b may be configured to receive the reinforcing bars 31 protruding from the upper ends of the side wall members 5a and 5b, thereby connecting the side wall members 5a and 5b to the corner members 12a and 12b. In addition, a plurality of reinforcing bars 45 protruding toward the inside of the box culvert 1 are provided on the inner sides of the upper ends of the corner members 12a and 12b. The corner members 12a and 12b each have a flat plate portion 13a and 13b.

[0031] Then, as shown in Figs. 5 and 6, a precast intermediate member 15 is installed between a pair of corner members 12a and 12b (top plate central portion construction process). As shown in the figures, the intermediate member 15 has a flat plate portion 16. At both widthwise ends of the intermediate member 15, a plurality of reinforcing bars 51 are provided protruding from the widthwise ends toward the outside (corner member direction). That is, the reinforcing bars 45 and the reinforcing bars 51 protrude in a direction facing each other. When the intermediate member 15 is installed, the reinforcing bars 45 and the reinforcing bars 51 are connected by a connecting means 55. The connecting means 55 is optional, and may be, for example, a mechanical joint using a coupler or the like. In addition, a main reinforcing bar 60 extending in a direction perpendicular to the reinforcing bars 45 and the reinforcing bars 51 (that is, the length direction of the box culvert 1) is installed.

[0032] Then, as shown in FIG. 7, cast-in-place concrete is poured into the gaps formed between the corner member 12a and the intermediate member 15, and between the corner member 12b and the intermediate member 15, to construct the beams 20a and 20b (beam construction process). The beams 20a and 20b extend in the length direction of the box culvert 1 and are integrally constructed by cast-in-place concrete. At that time, the reinforcing bars 45 and 51 connected by the above-mentioned connecting means 55 and the main reinforcing bars 60 are embedded in the cast-in-place concrete. As a result, the corner member 12a and the intermediate member 15, and the corner member 12b and the intermediate member 15 in the row adjacent to each other in the width direction of the box culvert 1 are connected to each other. Furthermore, a plurality of precast members (here, the corner members 12a and 12b and the intermediate member 15) arranged continuously in the length direction of the box culvert 1 are connected to each other. The top plate portion 10 that constitutes the ceiling surface of the box culvert 1 is constructed by parts of the corner members 12a, 12b (flat plate portions 13a, 13b), the intermediate member 15, and the beam portions 20a, 20b.

[0033] Then, as shown in Fig. 8, the bottom plate portion 3 is constructed between the bottom surface portions 6a, 6b at the lower ends of the side wall members 5a, 5b by pouring cast-in-place concrete. The bottom surface of the box culvert 1 is formed by this bottom plate portion 3 and the bottom surface portions 6a, 6b. When constructing the bottom plate portion 3, multiple reinforcing bars 32 are embedded in the poured concrete, and the side wall members 5a, 5b and the bottom plate portion 3 are connected and integrated.

[0034] As described above with reference to Figures 2 to 8, the pair of left and right side wall sections 5 made of precast members, the precast corner members 12a, 12b installed on the upper portions thereof, and the precast intermediate member 15 installed between the corner members 12a, 12b are integrated by the beam sections 20a, 20b made of cast-in-place concrete and the bottom plate section 3. In this manner, the box culvert 1 according to this embodiment is constructed.

[0035] <Reinforcement configuration within beams> Fig. 9 is a schematic explanatory diagram showing the reinforcing bar arrangement configuration embedded in the beams 20a and 20b of the box culvert 1 according to this embodiment. For the purpose of explanation, Fig. 9 illustrates a part of the box culvert 1, and shows the reinforcing bar arrangement configuration between the corner member 12a and the intermediate member 15 as an example. Fig. 10 is a partially enlarged view of the reinforcing bar arrangement configuration shown in Fig. 9. Note that this figure illustrates the stage before cast-in-place concrete is poured into the beams 20a, that is, the state before the reinforcing bars are embedded.

[0036] 9 and 10, in the gap between the corner member 12a and the intermediate member 15, a plurality of reinforcing bars 45 protruding from the corner member 12a and a plurality of reinforcing bars 51 protruding from the intermediate member 15 are connected and arranged by connecting means 55. A plurality of main reinforcing bars 60 are arranged so as to extend in the length direction of the box culvert 1, perpendicular to the reinforcing bars 45 and 51 extending in the width direction of the box culvert 1.

[0037] In addition, in the gap between the corner member 12a and the intermediate member 15, a ring-shaped reinforcing bar 65 may be arranged in a ring shape to surround at least a part of the multiple main reinforcing bars 60 extending in the length direction of the box culvert 1. As shown in Fig. 10, the ring-shaped reinforcing bar 65 is configured to be annular in the width direction of the box culvert 1, and reinforces the multiple main reinforcing bars 60 by surrounding them collectively.

[0038] With the reinforcing bars 45, reinforcing bars 51, main reinforcing bars 60, and ring-shaped reinforcing bars 65 in place, the beam section 20a is constructed by pouring in-situ concrete into the gap between the corner member 12a and the intermediate member 15. That is, the beam section 20a has the function of connecting the corner member 12a and the intermediate member 15 in the width direction, and also of connecting the corner members 12a and the intermediate members 15 that are arranged consecutively in the length direction.

[0039] <Effects of this embodiment> According to the box culvert 1 of this embodiment configured as described above, when constructing the top plate portion 10, a number of precast members (here, corner members 12a, 12b and intermediate member 15) arranged continuously in the longitudinal direction are used. Then, a construction method is adopted in which these precast members are connected in both the width direction and the length direction using beam portions 20a, 20b. This ensures sufficient rigidity of the box culvert 1. In particular, when a load is concentrated near the center of the top plate portion 10, the load (dead load and live load) is effectively distributed in the longitudinal direction, which allows for rationalization of member design and improvement of rigidity against bending in the longitudinal direction.

[0040] Moreover, in the box culvert 1 according to this embodiment, a plurality of precast members such as corner members 12a, 12b, intermediate member 15, and side wall members 5a, 5b are combined to construct the box culvert 1. In this way, by using split precast members, it is possible to improve the work efficiency during construction and the transportability of the members.

[0041] Although an example of an embodiment of the present invention has been described above, the present invention is not limited to the illustrated embodiment. It is clear that a person skilled in the art can come up with various modified or revised examples within the scope of the ideas described in the claims, and it is understood that these also naturally belong to the technical scope of the present invention.

[0042] In the above embodiment, the side wall portion 5 is described as being composed of a pair of left and right precast side wall members 5a, 5b arranged continuously in the longitudinal direction of the box culvert 1, but the configuration of the side wall portion 5 is not necessarily limited to this. That is, the side wall portion 5 may be composed of precast members, or may be composed of cast-in-place concrete. Furthermore, when the side wall portion 5 is composed of multiple side wall members 5a, 5b arranged continuously in the longitudinal direction, its length (the length in the longitudinal direction of the box culvert 1) is arbitrary, and it may be designed to span multiple corner members 12a, 12b, for example.

[0043] In the above embodiment, the top plate portion 10 is composed of the corner members 12a, 12b and the intermediate member 15, and the beam portions 20a, 20b are constructed in the two gaps formed between the corner member 12a and the intermediate member 15, and between the corner member 12b and the intermediate member 15. However, the configuration of the box culvert according to the present invention is not limited to this. Hereinafter, the configuration and construction method of the box culvert according to another embodiment of the present invention will be described with reference to the drawings. In the following other embodiments, components having the same functional configuration as the above embodiment are illustrated with the same reference numerals, and their description may be omitted.

[0044] <First Alternative Embodiment of the Present Invention> 11 to 17 are schematic explanatory diagrams of a method for constructing a box culvert 1a according to the first alternative embodiment of the present invention, and the construction process is shown in the order of Fig. 11 to Fig. 17. Note that the configuration of the reinforcing bars shown in Fig. 11 to Fig. 17 is one example, and the arrangement, number, etc. of these bars can be designed arbitrarily.

[0045] First, as shown in Fig. 11, a pair of left and right precast side wall members 5a, 5b are installed as in the above embodiment. These side wall members 5a, 5b are installed adjacent to each other in the length direction as shown in the figure. This forms a pair of left and right side wall portions 5 consisting of the multiple side wall members 5a, 5b. The side wall members 5a, 5b may be provided with multiple reinforcing bars 31 protruding from their upper ends and multiple reinforcing bars 32 protruding from the bottom surface portions 6a, 6b at their lower ends toward the inside of the box culvert.

[0046] Then, as shown in FIG. 12, the support 40 is installed in the center of the pair of side walls 5. Next, as shown in FIG. 13 and FIG. 14, corner members 70a, 70b are installed on the upper ends of the side wall members 5a, 5b constituting the side wall 5 on the pair of left and right side walls 5. At this time, the corner members 70a, 70b may be configured to receive the reinforcing bars 31 protruding from the upper ends of the side wall members 5a, 5b, thereby connecting the side wall members 5a, 5b and the corner members 70a, 70b. The corner members 70a, 70b are configured so that their inner ends face each other when installed, and a plurality of reinforcing bars 75a, 75b protruding inward are provided on the respective facing surfaces. The corner members 70a, 70b each have a flat plate portion 73a, 73b.

[0047] 15, the reinforcing bars 75a and 75b are connected by a connecting means 78. The connecting means 78 may be any as in the above embodiment. A main reinforcing bar 80 is installed between the corner member 70a and the corner member 70b, extending in a direction perpendicular to the reinforcing bars 75a and 75b (i.e., in the longitudinal direction of the box culvert 1a). Although not shown, a ring-shaped reinforcing bar may be arranged to surround at least a portion of the main reinforcing bar 80 as in the above embodiment.

[0048] Then, as shown in FIG. 16, cast-in-place concrete is poured into the gap formed between the corner member 70a and the corner member 70b to construct a beam portion 83. The beam portion 83 is integrally constructed by cast-in-place concrete so as to extend in the longitudinal direction of the box culvert 1a. At this time, the reinforcing bars 75a and 75b connected by the connecting means 78 and the main reinforcing bars 80 are buried inside. This results in a configuration in which the corner member 70a and the corner member 70b arranged in adjacent rows in the width direction of the box culvert 1a are connected. Furthermore, a configuration in which a plurality of precast members (here, the corner member 70a and the corner member 70b) arranged continuously in the longitudinal direction of the box culvert 1a are connected to each other. This results in the construction of the top plate portion 10a that constitutes the ceiling surface of the box culvert 1a by the corner member 70a, the corner member 70b, and the beam portion 83 located therebetween.

[0049] Then, as shown in Fig. 17, the bottom plate portion 3 is constructed between the bottom surface portions 6a, 6b at the lower ends of the side wall members 5a, 5b by pouring cast-in-place concrete. The bottom surface of the box culvert 1a is formed by this bottom plate portion 3 and the bottom surface portions 6a, 6b. When constructing the bottom plate portion 3, multiple reinforcing bars 32 are embedded in the poured concrete, and the side wall members 5a, 5b and the bottom plate portion 3 are connected and integrated.

[0050] In the box culvert 1a according to the first alternative embodiment, the top plate portion 10a is composed of corner members 70a and 70b, and a beam portion 83 located between them. That is, a two-row configuration is adopted as multiple rows of precast members arranged continuously in the longitudinal direction of the box culvert 1a, and corner members 70a and 70b are used. In other words, the intermediate member 15 described in the above embodiment is not used. Therefore, in addition to the effects described in the above embodiment, further improvements in workability are achieved.

[0051] <Second Alternative Embodiment of the Present Invention> 18 to 22 are schematic explanatory diagrams of a method for constructing a box culvert 1b according to a second alternative embodiment of the present invention, and the construction process is shown in the order of Fig. 18 to Fig. 22. Note that, for simplification, some reinforcing bars are not shown in Fig. 18 to Fig. 22.

[0052] First, as shown in Fig. 18, a pair of left and right precast side wall members 5a, 5b are installed as in the above embodiment. These side wall members 5a, 5b are installed adjacent to each other in the length direction as shown in the figure. This forms a pair of left and right side wall portions 5 consisting of the multiple side wall members 5a, 5b. The side wall members 5a, 5b may be provided with multiple reinforcing bars (not shown) protruding from their upper ends and multiple reinforcing bars (not shown) protruding from the bottom surface portions 6a, 6b at their lower ends toward the inside of the box culvert.

[0053] Further, a middle wall member 90 is installed, which includes a bottom plate portion 3 constituting a part of the bottom surface of the box culvert 1b, and a lower end portion 92 constituting a part of the bottom surface at approximately the center of the bottom surface. The middle wall member 90 includes a wall portion 91 constituting a part of an intermediate wall 110 described below, and the lower end portion 92. The middle wall members 90 are, for example, precast members, and are installed so that multiple middle wall members 90 are adjacent to each other in the length direction at the center in the width direction.

[0054] Then, as shown in Fig. 19, the shoring 40 is installed. For example, as shown in the figure, the shoring 40 may be installed at two locations on both sides of the middle wall member 90 in the width direction. Next, as shown in Fig. 20, corner members 100a, 100b are installed on the upper ends of the side wall members 5a, 5b constituting the side wall portion 5 on the pair of left and right side wall portions 5. A plurality of reinforcing bars 105a, 105b protruding inward are provided on the inner ends of the corner members 100a, 100b. The corner members 100a, 100b each have a flat plate portion 103a, 103b.

[0055] A precast intermediate member 15 is placed between the pair of corner members 100a, 100b. That is, the corner members 100a and 100b constitute the first and second rows of precast members that are made up of three rows in the width direction, and the intermediate member 15 constitutes the third row of precast members.

[0056] As shown in the figure, the intermediate member 15 has a flat plate portion 16 and further has a leg portion 110 extending downward from the flat plate portion 16. That is, the leg portion 110 is combined with the above-mentioned middle wall member 90 to form the intermediate wall of the box culvert 1b. At both widthwise ends of the intermediate member 15, a plurality of reinforcing bars 51 are provided protruding outward (toward the corner members) from the widthwise ends. The reinforcing bars 105a, 105b and the reinforcing bars 51 are connected in the same manner as in the above-mentioned embodiment.

[0057] Then, as shown in Fig. 21, cast-in-place concrete is poured into the gaps formed between the corner member 100a and the intermediate member 15, and between the corner member 100b and the intermediate member 15, to construct the beams 20a and 20b. At this time, in addition to the reinforcing bars 105a and 105b and the reinforcing bar 51, main reinforcing bars (not shown here) and ring-shaped reinforcing bars (not shown here) are embedded inside the beams 20a and 20b. In this way, the top plate 10b that constitutes the ceiling surface of the box culvert 1b is constructed by parts of the corner members 100a and 100b, the intermediate member 15, and the beams 20a and 20b.

[0058] Then, as shown in FIG. 22, the support 40 is removed, and the box culvert 1b according to the second alternative embodiment is constructed.

[0059] According to the box culvert 1b according to the second alternative embodiment constructed as described above, in addition to the configuration described in the above embodiment, an intermediate wall including a middle wall member 90 and a leg portion 110 is provided. As a result, in the box culvert 1b, two routes are configured for the passage of, for example, automobiles, railway vehicles, etc. That is, the same effects as those of the above embodiment can be enjoyed in the culvert with a two-route configuration.

[0060] In addition, the effects described in this specification are merely explanatory or exemplary and are not limiting. In other words, the technology according to the present disclosure may achieve other effects that are apparent to a person skilled in the art from the description of this specification in addition to or in place of the above effects. [Industrial Applicability]

[0061] The present invention is applicable to box culverts and methods of constructing same. [Explanation of symbols]

[0062] 1, 1a, 1b...Box culvert 3…Bottom plate part 5…Side wall 5a, 5b...Side wall members 6a, 6b...Bottom portion (of side wall member) 10…Top plate part 12a, 12b... Corner members 13a, 13b...(corner member) flat plate portion 15...Intermediate part 16...(Intermediate part) flat plate section 20a, 20b...beam section 31...Reinforcing bar (protruding from side wall member) 32...Reinforcing bar (protruding from the bottom) 40…Shoring 45...Reinforcing bar (protruding from corner member) 51...Reinforcing bar (protruding from intermediate member) 55...Connection means 60…Main rebar 65…Ring-shaped steel bar 70a, 70b...corner members (in the first alternative embodiment) 75a, 75b...(in the first alternative embodiment) reinforcing bar 78...(in the first alternative embodiment) connecting means 80...Main reinforcing bar (in the first alternative embodiment) 90...Center wall member 91...Wall part 92...Lower end 100a, 100b...corner members (in the second alternative embodiment)

Claims

1. A box culvert having a top plate portion constituting a ceiling surface and a side wall portion constituting a side surface, The top plate portion includes a plurality of rows of precast members arranged in succession in the longitudinal direction of the box culvert, and a cast-in-place concrete beam portion located between adjacent rows of the precast members and extending in the longitudinal direction of the box culvert; Within the beam portion, a reinforcing bar protruding from one row of the precast members and a reinforcing bar protruding from the other row of the precast members are connected to each other; A main reinforcing bar extending in the longitudinal direction of the box culvert is embedded inside the beam portion, A box culvert, characterized in that the beam portion and the main reinforcing bars therein are constructed across multiple precast members adjacent in the longitudinal direction of the box culvert.

2. 2. The box culvert of claim 1, wherein the side wall portion is constructed by arranging a plurality of precast side wall members having the same length as the precast member constituting the top plate portion in the longitudinal direction of the box culvert in succession in the longitudinal direction of the box culvert.

3. The plurality of rows of precast members are comprised of three rows; The precast members in the first and second rows are corner members having flat plate portions extending in the width direction of the box culvert, and the corner members are respectively disposed on a pair of the side wall portions; The precast member in the third row is an intermediate member having a flat plate portion extending in the width direction of the box culvert, and is installed between the precast members in the first row and the precast members in the second row; A box culvert as described in claim 1 or 2, characterized in that a beam portion is provided between the precast members in the first row and the precast members in the third row, and between the precast members in the second row and the precast members in the third row.

4. The precast member of the third row further includes a leg portion extending downwardly from the plate portion; The box culvert according to claim 3, wherein the leg portion constitutes a part or all of the intermediate wall of the box culvert in the height direction.

5. A method for constructing a box culvert having a top plate portion constituting a ceiling surface and a side wall portion constituting a side surface, comprising: a corner construction process for constructing a corner by continuously arranging precast corner members having flat plate portions extending in the width direction of the box culvert on the pair of side wall portions in the length direction of the box culvert; a top plate central portion construction process for constructing a top plate central portion by continuously arranging precast intermediate members having flat plate portions extending in the width direction of the box culvert between the corner portions constructed on the pair of side wall portions in the length direction of the box culvert; and a beam construction process for constructing a beam extending across a plurality of intermediate members adjacent in the longitudinal direction of the box culvert along a gap provided between the corner portion and the central portion of the top plate, In the beam construction process, the reinforcing bars protruding from the corner members and the intermediate members in the directions facing each other are connected to each other in the gaps, and further, main reinforcing bars extending in the longitudinal direction of the box culvert are arranged across a plurality of the intermediate members adjacent in the longitudinal direction of the box culvert, and then the beams are constructed by pouring in-situ concrete into the gaps; A method for constructing a box culvert, characterized in that the top plate portion is formed by the corner portion, the central portion of the top plate, and the beam portion.

6. A method for constructing a box culvert having a top plate portion constituting a ceiling surface and a side wall portion constituting a side surface, comprising: a corner construction process for constructing a corner by continuously arranging precast corner members having flat plate portions extending in the width direction of the box culvert on the pair of side wall portions in the length direction of the box culvert; and a beam construction process for constructing a beam extending across a plurality of adjacent corner members in the longitudinal direction of the box culvert along a gap provided between a pair of adjacent flat plate portions between the corner portions formed on a pair of the side wall portions, In the beam construction process, reinforcing bars protruding from a pair of corner members in directions facing each other are connected to each other in the gap, and further, main reinforcing bars extending in the longitudinal direction of the box culvert are arranged across a plurality of adjacent corner members in the longitudinal direction of the box culvert, and then, cast-in-place concrete is poured into the gap to construct the beam, A method for constructing a box culvert, characterized in that the top plate portion is formed by the corner portion and the beam portion.

Images