JP7670979B2 - Box culvert and its construction method - Google Patents

Description

The present invention relates to a box culvert and a method for constructing the same.

In recent years, construction of new trunk roads has been shifting from plains to mountainous areas, with an increase in the number of new roads passing through steep mountainous areas. 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 is on the rise. One example of a culvert structure is the box culvert, which has a roughly rectangular cross section. Culvert structures are constructed using a variety of construction methods, for example, by combining precast concrete members and cast-in-place concrete.

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 placed on top to integrate the side walls and the precast top plate.

For example, Patent Document 2 discloses a construction technique for a split-type rigid culvert. Patent Document 2 discloses a structure with a top plate that is made up of two or more top plate unit blocks connected together. Between the two or more top plate unit blocks, a joint structure is used in which mechanical joints are covered with concrete filling sections.

Japanese Patent Application Publication No. 11-229412 JP 2022-34412 A

The large box culvert described in Patent Document 1 is configured so that concrete is poured into a precast support block when erecting a precast top plate at the top of the side wall. This precast support block with poured concrete 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.

In addition, in the split rigid culvert described in Patent Document 2, the top plate members are split (top plate unit blocks) due to the constraints of 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.

In addition, 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) may not be distributed, and the rigidity of the culvert may not be adequately guaranteed. In addition, when trying to guarantee the rigidity of the culvert, it is necessary to increase the thickness of the components, which may increase the amount of concrete used and raise concerns about costs.

In recent years, when constructing culvert structures, so-called precast concrete members (also simply called precast members) are sometimes used; members are prefabricated in a factory or other location, transported to the site, and assembled. Traditionally, when constructing a top plate using precast members, the divided top plate members were first joined together on an assembly frame, and the integrated top plate was then lifted and installed. This posed problems, such as the need to secure a yard for constructing the assembly frame, increased costs, and the need for larger cranes for lifting.

In view 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 precast members are used in the construction of a box culvert, streamlines member design by distributing loads in the longitudinal direction, and improves rigidity against bending in the longitudinal direction.

In order to achieve the above-mentioned object, according to the present invention, there is provided a box culvert having a top plate portion that forms a ceiling surface and a side wall portion that forms a side surface, wherein 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 beam portion made of cast-in-place concrete that extends in the longitudinal direction of the box culvert between adjacent rows of the precast members, wherein inside the beam portion, 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, main reinforcing bars extending in the longitudinal direction of the box culvert are buried inside the beam portion, and the beam portion and the main reinforcing bars therein are constructed across a plurality of the precast members adjacent in the longitudinal direction of the box culvert .

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

The multiple rows of precast members are composed 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 arranged on a pair of the side wall portions, respectively, and the precast members in the third row are intermediate members having flat plate portions extending in the width direction of the box culvert and are installed between the precast members in the first row and the precast members in the second row, and the 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.

The precast members of the third row may further include legs extending downward from the flat plate portion, and the legs may constitute part or all of the height of the intermediate wall of the box culvert.

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, the method comprising the steps of: 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 gap portion provided between the corner portion and the top plate center portion. 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 the gap, in which the beam construction process connects the reinforcing bars protruding in opposite directions from the corner member and the intermediate member in the gap, and further arranges main reinforcing bars extending in the longitudinal direction of the box culvert across a plurality of intermediate members adjacent in the longitudinal direction of the box culvert , and then pours in-situ concrete into the gap to construct the beam, and the top plate is formed by the corner member, the central portion of the top plate, and the beam.

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: 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 longitudinal direction of the box culvert; and a beam portion construction step of constructing a beam portion extending across a plurality of the corner members adjacent in the longitudinal direction of the box culvert along a gap portion provided between a pair of adjacent flat plate portions between the corner portions constructed on the pair of side wall portions, the beam portion construction step connecting reinforcing bars protruding in directions facing each other from the pair of corner members in the gap portion, and further arranging main reinforcing bars extending in the longitudinal direction of the box culvert across a plurality of the corner members adjacent in the longitudinal direction of the box culvert , and then pouring cast-in-place concrete into the gap portion to construct the beam portion, and the top plate portion is constituted by the corner portion and the beam portion.

According to the present invention, it is possible to improve the workability of box culverts when using precast members, and also to streamline member design by distributing loads in the longitudinal direction and to improve rigidity against bending in the longitudinal direction.

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.

1 is a schematic explanatory diagram of a box culvert according to an embodiment of the present invention. FIG. FIG. 1 is a schematic diagram illustrating a method for constructing a box culvert. FIG. 1 is a schematic diagram illustrating a method for constructing a box culvert. FIG. 1 is a schematic diagram illustrating a method for constructing a box culvert. FIG. 1 is a schematic diagram illustrating a method for constructing a box culvert. FIG. 1 is a schematic diagram illustrating a method for constructing a box culvert. FIG. 1 is a schematic diagram illustrating a method for constructing a box culvert. FIG. 1 is a schematic diagram illustrating a method for constructing a box culvert. FIG. 2 is a schematic explanatory diagram showing the reinforcing bar arrangement configuration embedded in the beam portion of a box culvert. FIG. 10 is a partially enlarged view of the reinforcement configuration shown in FIG. FIG. 11 is a schematic explanatory diagram of a method for constructing a box culvert according to a first alternative embodiment. FIG. 11 is a schematic explanatory diagram of a method for constructing a box culvert according to a first alternative embodiment. FIG. 11 is a schematic explanatory diagram of a method for constructing a box culvert according to a first alternative embodiment. FIG. 11 is a schematic explanatory diagram of a method for constructing a box culvert according to a first alternative embodiment. FIG. 11 is a schematic explanatory diagram of a method for constructing a box culvert according to a first alternative embodiment. FIG. 11 is a schematic explanatory diagram of a method for constructing a box culvert according to a first alternative embodiment. FIG. 11 is a schematic explanatory diagram of a method for constructing a box culvert according to a first alternative embodiment. FIG. 11 is a schematic explanatory diagram of a method for constructing a box culvert according to a second alternative embodiment. FIG. 11 is a schematic explanatory diagram of a method for constructing a box culvert according to a second alternative embodiment. FIG. 11 is a schematic explanatory diagram of a method for constructing a box culvert according to a second alternative embodiment. FIG. 11 is a schematic explanatory diagram of a method for constructing a box culvert according to a second alternative embodiment. FIG. 11 is a schematic explanatory diagram of a method for constructing a box culvert according to a second alternative embodiment.

The following describes an embodiment of the present invention with reference to the drawings. In this specification and the drawings, components that have substantially the same functional configuration may be given the same reference numerals to avoid repetitive explanation. Note that in this embodiment, for the purpose of explanation, some illustrations of the reinforcement structure and reinforcement arrangement may be omitted, or reinforcement bars inside the components may be illustrated.

<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 a trunk road or a railway (not shown), and a path (not shown) for automobiles, railway vehicles, etc. is laid inside the box culvert 1. 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.

As shown in FIG. 1, the box culvert 1 includes a bottom plate 3 laid on the ground, a side wall 5 constructed vertically to the ground, and a top plate 10 constructed approximately parallel to the ground at the top of the side wall 5. The top plate 10 is placed on the top of the side wall 5 and is provided to form the ceiling surface of the box culvert 1. In addition, a bottom plate 3 is provided that is parallel to the top plate 10 and forms at least a part of the bottom surface located at the bottom of the box culvert 1.

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. As shown in FIG. 1, the side wall members 5a, 5b may include bottom surface portions 6a, 6b at their lower ends that form part of the bottom surface of the box culvert 1.

The top plate portion 10 also includes multiple rows of precast members arranged continuously along the length 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 form the first and second rows of precast members that are made up of three rows in the width direction, and the intermediate member 15 forms the third row of precast members.

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 that extend in the width direction of the box culvert 1, and the intermediate member 15 also has a similar flat plate portion 16.

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 Figures 9 and 10, the beam portions 20a and 20b have multiple 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, they also function to connect multiple precast members (here, the corner members 12a, 12b and the intermediate member 15) that are continuously arranged in the longitudinal direction of the box culvert 1 to each other, distributing the load.

<How to construct 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.

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. This forms a pair of left and right side wall sections 5 consisting of multiple side wall members 5a, 5b.

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

Next, as shown in FIG. 3, shoring 40 is installed on the inside of the side wall 5. Here, shoring 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 that constitute 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 inside 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.

Then, as shown in Figures 5 and 6, a precast intermediate member 15 is installed between a pair of corner members 12a, 12b (top plate central part 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 that protrude from the widthwise ends toward the outside (corner member direction). That is, the reinforcing bars 45 and the reinforcing bars 51 protrude in directions 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 is installed that extends in a direction perpendicular to the reinforcing bars 45 and the reinforcing bars 51 (i.e., the length direction of the box culvert 1).

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 adjacent rows in the width direction of the box culvert 1 are connected. Furthermore, the multiple precast members (here, the corner members 12a, 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 10 that constitutes the ceiling surface of the box culvert 1 is constructed by parts of the corner members 12a and 12b (flat plate portions 13a and 13b), the intermediate member 15, and the beam portions 20a and 20b.

Then, as shown in FIG. 8, the bottom plate portion 3 is constructed by pouring cast-in-place concrete between the bottom surface portions 6a, 6b at the lower ends of the side wall members 5a, 5b. 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.

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 tops of the side wall sections 5, and the precast intermediate member 15 installed between the corner members 12a, 12b are integrated by the beam sections 20a, 20b and the bottom plate section 3 made of cast-in-place concrete. In this manner, the box culvert 1 according to this embodiment is constructed.

<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. Fig. 9 shows a part of the box culvert 1 for the purpose of explanation, 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 shows the stage before the cast-in-place concrete is poured into the beams 20a, i.e., the state before the reinforcing bars are embedded.

As shown in Figures 9 and 10, in the gap between the corner member 12a and the intermediate member 15, multiple reinforcing bars 45 protruding from the corner member 12a and multiple reinforcing bars 51 protruding from the intermediate member 15 are connected and arranged by a connecting means 55. Then, multiple main reinforcing bars 60 are arranged, which extend in the length direction of the box culvert 1 and are perpendicular to these reinforcing bars 45 and reinforcing bars 51 extending in the width direction of the box culvert 1.

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 portion 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 together.

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

<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 plurality 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 plurality of precast members are connected in both the width direction and the length direction using beams 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.

In addition, in the box culvert 1 according to this embodiment, the box culvert 1 is constructed by combining multiple precast components, such as corner members 12a, 12b, intermediate member 15, and side wall members 5a, 5b. In this way, by using split precast components, it is possible to improve the work efficiency during construction and the transportability of the components.

Although one embodiment of the present invention has been described above, the present invention is not limited to the illustrated form. 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 fall within the technical scope of the present invention.

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.

In the above embodiment, the top plate portion 10 is composed of corner members 12a, 12b and an intermediate member 15, and the beam portions 20a, 20b are constructed in 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. Below, 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. Note that 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.

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

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 longitudinal direction as shown in the figure. This forms a pair of left and right side wall sections 5 consisting of 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 surfaces 6a, 6b at their lower ends toward the inside of the box culvert.

Then, as shown in FIG. 12, a 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 that constitute 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. In addition, 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 that protrude inward are provided on each of the opposing surfaces. The corner members 70a, 70b each have a flat plate portion 73a, 73b.

As shown in FIG. 15, the reinforcing bars 75a and 75b are connected by a connecting means 78. The connecting means 78 is optional, as in the above embodiment. In addition, 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.

Then, as shown in FIG. 16, cast-in-place concrete is poured into the gap formed between the corner members 70a and 70b to construct the beam 83. The beam 83 is integrally constructed with 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 embedded inside. This results in a configuration in which the corner members 70a and 70b arranged in adjacent rows in the width direction of the box culvert 1a are connected. Furthermore, a configuration in which multiple precast members (here, the corner members 70a and 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 10a that constitutes the ceiling surface of the box culvert 1a, consisting of the corner members 70a and 70b and the beam 83 located between them.

Then, as shown in FIG. 17, the bottom plate portion 3 is constructed by pouring cast-in-place concrete between the bottom surface portions 6a, 6b at the lower ends of the side wall members 5a, 5b. 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.

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. In other words, 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 configuration does not use the intermediate member 15 described in the above embodiment. Therefore, in addition to the effects described in the above embodiment, further improvements in workability are achieved.

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

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 longitudinal direction as shown. This forms a pair of left and right side wall sections 5 consisting of 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, or multiple reinforcing bars (not shown) protruding from the bottom surfaces 6a, 6b at their lower ends toward the inside of the box culvert.

In addition, a middle wall member 90 is installed, which includes a bottom plate portion 3 that constitutes part of the bottom surface of the box culvert 1b, and a lower end portion 92 that constitutes part of the bottom surface at approximately the center of the bottom surface. The middle wall member 90 includes a wall portion 91 that constitutes part of the 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 members are adjacent to each other in the length direction at the center in the width direction.

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 that constitute the side wall portion 5 on the pair of left and right side wall portions 5. A plurality of reinforcing bars 105a, 105b that protrude 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.

A precast intermediate member 15 is then installed between the pair of corner members 100a, 100b. That is, corner member 100a and corner member 100b form the first and second rows of precast members, which are made up of three rows in the width direction, and intermediate member 15 forms the third row of precast members.

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 that protrude outward from the widthwise ends (towards the corner members). The reinforcing bars 105a, 105b and the reinforcing bars 51 are connected in the same manner as in the above embodiment.

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, 105b and 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.

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

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. In other words, the same effects as those of the above embodiment can be obtained even in a culvert with a two-route configuration.

Furthermore, the effects described in this specification are merely descriptive or exemplary and are not limiting. In other words, the technology disclosed herein may achieve other effects that are apparent to a person skilled in the art from the description in this specification, in addition to or in place of the above effects.

The present invention can be applied to box culverts and their construction methods.

DESCRIPTION OF SYMBOLS 1, 1a, 1b...Box culvert 3...Bottom plate portion 5...Side wall portion 5a, 5b...Side wall member 6a, 6b...Bottom surface portion (of side wall member) 10...Top plate portion 12a, 12b...Corner member 13a, 13b...Flat plate portion (of corner member) 15...Intermediate member 16...Flat plate portion (of intermediate member) 20a, 20b...Beam portion 31...Reinforcing bar (protruding from side wall member) 32...Reinforcing bar (protruding from bottom surface portion) 40...Support 45...Reinforcing bar (protruding from corner member) 51...Reinforcing bar (protruding from intermediate member) 55...Connecting means 60...Main reinforcing bar 65...Ring-shaped reinforcing bar 70a, 70b...Corner member (in first alternative embodiment) 75a, 75b...Reinforcing bar (in first alternative embodiment) 78... (in the first alternative embodiment) Connection means 80... (in the first alternative embodiment) Main reinforcing bar 90... Middle wall member 91... Wall portion 92... Lower end portion 100a, 100b... (in the second alternative embodiment) Corner member

Claims (6)

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 . The box culvert of claim 1, characterized in that the side wall portion is constructed by continuously arranging a plurality of precast side wall members in the longitudinal direction of the box culvert, the precast members having the same length as the precast members constituting the top plate portion in the longitudinal direction of the box culvert. 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. 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. 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. 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 the corner members adjacent 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.

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