JP2024084389A - Drain ditch unit - Google Patents

Abstract

To provide a drain ditch unit capable of simultaneously ensuring slip resistance of an automobile and the like and drainage performance of rainwater and the like.SOLUTION: A metallic drain ditch unit 1 comprises: a flowing water plate 2 with a bottom wall part 2a; and a guard plate 3 provided to cover the flowing water plate 2 from above and having a drainage hole 3c penetrating in a depthwise direction, wherein water flowing on a roadway D on a bridge B is configured to be introduced into the interior as drainage through the drainage hole 3c, and is configured to be received by the bottom wall part 2a and allowed to flow in a predetermined drainage flow direction. An upper surface of the guard plate 3 is provided with a first area A1 in which an anti-slip layer L is provided, and a second area A2 in which the anti-slip layer L is not provided, and the second area A2 is configured to connect a peripheral edge R of the guard plate 3 with the drainage hole 3c.SELECTED DRAWING: Figure 8

Description

The present invention relates to a drainage unit that can be installed on a road.

Conventionally, drainage ditch units that are installed on the shoulders of roads such as bridges, viaducts, underpasses, tunnels, and streets have been known. For example, the drainage ditch unit disclosed in Patent Document 1 includes a water flow plate in which a water passage is formed, and a guard plate that is arranged to cover the water flow plate from above and has drainage holes that penetrate in the thickness direction. Rainwater that falls on the road surface flows over the road surface to the shoulder side of the road, and is then introduced into the drainage ditch unit through the drainage holes. The rainwater that is introduced into the drainage ditch unit flows through the water passage and is then drained into a river, sewer, etc. from a drainage pipe installed at the end of the water passage.

JP 2019-19636 A

For example, when a drainage ditch unit is temporarily installed on a bridge undergoing repair work, rather than on an open bridge, the upper surface of the drainage ditch unit may be temporarily used as a road for automobiles, motorcycles, bicycles, pedestrians, etc. to pass through. The drainage ditch unit is made of metal such as steel, and therefore has a lower slip resistance than the asphalt road surface on which automobiles pass. Therefore, if the upper surface of the guard plate in the drainage ditch unit becomes wet due to rainfall, there is a concern that automobiles passing over the guard plate may become slippery. In response to this, it is conceivable to provide an anti-slip layer that can prevent automobiles from slipping by applying paint or the like that can increase the slip resistance to the entire upper surface of the guard plate. However, if an anti-slip layer is provided on the entire upper surface of the guard plate, the anti-slip layer may hinder the flow of rainwater, etc. from the periphery of the guard plate to the drainage hole, which may deteriorate the drainage performance of the drainage ditch unit.

The present invention was made in consideration of these points, and its purpose is to provide a drainage groove unit that can simultaneously prevent slipping on automobiles and ensure drainage performance for rainwater, etc.

To achieve the above objective, the present invention is characterized by providing an anti-slip layer that avoids the area connecting the upper peripheral edge of the guard plate and the drainage hole.

Specifically, the target is a metal drainage groove unit that includes a water flow plate having a bottom wall portion, and a guard plate that is arranged to cover the water flow plate from above and has drainage holes that penetrate in the thickness direction, and is configured to introduce water flowing on the road surface into the interior through the drainage holes as drainage, and to receive the water at the bottom wall portion and allow it to flow in a specified drainage flow direction, and the following solution has been devised.

That is, in the first invention, the upper surface of the guard plate is provided with a first region in which an anti-slip layer is provided and a second region in which the anti-slip layer is not provided, and the second region is configured to connect the periphery of the guard plate to the drainage hole.

The second invention is characterized in that in the first invention, the drainage flow direction of the flow plate is set to follow the extension direction of the road, and the second area is arranged to extend horizontally in a direction intersecting the drainage flow direction.

The third invention is characterized in that, in the second invention, a plurality of the first regions and a plurality of the second regions are provided, and the first regions and the second regions are provided alternately along the drainage flow direction.

The fourth invention is characterized in that in the first invention, at least one of the upper surface of the bottom wall portion and the lower surface of the guard plate is provided with a load transmission portion that transmits a load acting on the guard plate from above to the bottom wall portion.

The fifth invention is characterized in that in the fourth invention, the load transmission section includes a plurality of ribs arranged at a predetermined interval along the upper surface of the bottom wall section, dividing the bottom wall section into a first water passage section and a second water passage section, and the drainage hole is arranged at a position corresponding to the first water passage section.

The sixth invention is the fifth invention, characterized in that the rib protrudes downward from the underside of the guard plate.

The seventh invention is the fourth invention, characterized in that the load transmission part extends in the vertical direction and includes a cylindrical round support part, and the round support part is disposed close to the drainage hole.

In the first invention, the anti-slip layer provided in the first region on the top surface of the guard plate increases the slip resistance, preventing automobiles and the like from slipping when they pass over the guard plate. In addition, the second region provided to connect the top periphery of the guard plate with the drainage hole does not have an anti-slip layer, so rainwater and the like flows more easily through it than through the first region. In other words, rainwater and the like that reaches the top periphery of the drainage groove unit from the road surface flows smoothly through the second region on the top surface of the drainage groove unit to the drainage hole. This prevents the drainage performance of the drainage groove unit from deteriorating.

In the second invention, for example, when the drainage groove unit is installed on the shoulder of a road in a position where the drainage flow direction and the road extension direction are approximately the same, rainwater, etc. on the road surface will flow horizontally toward the drainage groove unit in a direction that intersects with the drainage flow direction of the drainage groove unit. Here, a second area is provided on the upper surface of the guard plate along approximately the same direction as the rainwater, etc. flows into the drainage groove unit, so that rainwater, etc. on the road surface will flow smoothly through the second area into the drain hole. This prevents the drainage performance of the drainage groove unit from deteriorating.

In the third invention, the first and second regions are arranged alternately along the drainage flow direction, so that, for example, it is possible to prevent the second regions from being arranged biased toward the upstream or downstream side of the drainage flow direction. This makes it possible to reliably prevent automobiles and the like from slipping when passing over the drainage groove unit along the drainage flow direction.

In the fourth invention, even if a truck passes over the guard plate and a relatively large load acts on the guard plate from above, the load is transmitted to the bottom wall via the load transmission section and can be received by the bottom wall. This makes it possible to prevent the guard plate from being deformed.

In the fifth invention, when rainwater, etc. introduced into the first water passage section through the drainage hole passes between the ribs provided between the first water passage section and the second water passage section and flows into the second water passage section, fallen leaves and other debris contained in the rainwater etc. are caught by the ribs and collected. This makes it possible to prevent debris from entering the second water passage section, and prevents the drainage performance of the drainage groove unit from deteriorating due to debris accumulating in the second water passage section.

In the sixth invention, for example, when the guard plate is removed from the drainage groove unit, the rib separating the first water passage section and the second water passage section is no longer present on the water flow plate, which prevents the rib from getting in the way when cleaning the water flow plate of the drainage groove unit.

In the seventh invention, for example, when a car or the like passes over the guard plate, even if the wheels of the car or the like pass over the drainage hole, the load of the car or the like is transmitted to the bottom wall portion by the round support portion, and the load is received by the bottom wall portion. This makes it possible to prevent the surrounding area of the drainage hole in the guard plate from being deformed by the load of the car or the like.

FIG. 2 is a plan view showing a drainage groove unit according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. FIG. 2 is a schematic cross-sectional view taken along line III-III in FIG. 1 . 1 is a schematic cross-sectional view showing a state in which a drainage ditch unit according to an embodiment of the present invention is installed on a bridge. 1 is a schematic cross-sectional view showing a state in which a drainage groove unit according to an embodiment of the present invention is temporarily installed on a bridge. FIG. 11 is a plan view showing an anti-slip layer of a drainage groove unit according to a comparative example. 10 is a schematic cross-sectional view showing a drainage groove unit according to a comparative example installed on a bridge. FIG. FIG. 2 is a plan view showing an anti-slip layer of a drainage groove unit according to an embodiment of the present invention. 1 is a schematic cross-sectional view showing a state in which a drainage groove unit according to an embodiment of the present invention is installed on a bridge. 1 is a schematic cross-sectional view showing a state in which a drainage groove unit according to an embodiment of the present invention is temporarily installed on a bridge. FIG. 9 is a view corresponding to FIG. 8 according to a modified example.

The following describes in detail an embodiment of the present invention with reference to the drawings. Note that the following description of the preferred embodiment is essentially merely exemplary.

Figure 1 shows a drainage ditch unit 1 according to an embodiment of the present invention. The drainage ditch unit 1 is a plate type with a flat upper surface and is approximately rectangular in plan view. The drainage ditch unit 1 is designed to be installed or temporarily installed on the shoulder of a road, such as a bridge, with its longitudinal direction aligned with the direction in which the road extends. In this embodiment, the longitudinal direction of the drainage ditch unit 1 is simply referred to as the "longitudinal direction", and the horizontal direction that intersects with the longitudinal direction is referred to as the "intersecting direction".

The drainage groove unit 1 is made of metal, such as steel, and as shown in FIG. 2, includes a water flow plate 2 having a wide U-shaped cross section, and a guard plate 3 that is provided to cover the water flow plate 2 from above. The guard plate 3 can be removed from the water flow plate 2.

The water flow plate 2 has a bottom wall portion 2a that is generally plate-shaped and has a horizontally extending upper surface, and a first side wall portion 2b and a second side wall portion 2c that protrude upward from both end edges of the bottom wall portion 2a in the intersecting direction.

A first angle 4a having a generally L-shape is fixed to one surface of the first side wall portion 2b in the intersecting direction. A second angle 4b having a generally L-shape is fixed to the other surface of the second side wall portion 2c in the intersecting direction. The drainage groove unit 1 is fixed to the shoulder of a road such as a bridge by the first angle 4a and the second angle 4b.

A roughly L-shaped receiving angle 5 is fixed to one surface of the second side wall 2c in the intersecting direction. The receiving angle 5 is provided with a receiving portion 5a that extends to one side in the intersecting direction, and the upper surface of the receiving portion 5a is flat.

The guard plate 3 is provided with a top wall portion 3a that is generally plate-shaped and extends horizontally, and a third side wall portion 3b that protrudes downward from one end edge of the top wall portion 3a in the transverse direction. The third side wall portion 3b on one side of the guard plate 3 in the transverse direction is supported from below by the bottom wall portion 2a, and the other end of the guard plate 3 in the transverse direction is supported from below by the receiving portion 5a.

The top wall portion 3a is provided with a plurality of drainage holes 3c that penetrate in the thickness direction. The plurality of drainage holes 3c are elongated in plan view and are arranged in parallel along the longitudinal direction as shown in FIG. 1. Rainwater flowing on the road surface is introduced into the drainage groove unit 1 as drainage through the drainage holes 3c and is received by the bottom wall portion 2a.

As shown in Figs. 1 and 3, the underside of the top wall 3a is provided with a number of round supports 3d and a number of ribs 3e that protrude downward from the underside, that is, extend in the vertical direction. The round supports 3d are cylindrical and are arranged in parallel along the longitudinal direction. Some of the round supports 3d are also located close to the drainage holes 3c.

The ribs 3e are arranged at a predetermined interval from each other in the longitudinal direction and along the upper surface of the bottom wall portion 2a. The ribs 3e divide the bottom wall portion 2a into a first water passage portion 2d and a second water passage portion 2e provided on the other side of the first water passage portion 2d in the intersecting direction. In this embodiment, the width of the first water passage portion 2d is set larger than the width of the second water passage portion 2e.

A drain hole 3c is provided in the top wall 3a at a position corresponding to the first water passage section 2d, i.e., at a position covering the first water passage section 2d. This allows rainwater, etc. outside the drain unit 1 to be introduced into the first water passage section 2d inside the drain unit 1 through the drain hole 3c.

When rainwater, etc. introduced into the first water passage section 2d passes between the ribs 3e provided between the first water passage section 2d and the second water passage section 2e and flows into the second water passage section 2e, the fallen leaves and other debris contained in the rainwater are caught by the ribs 3e and collected. The rainwater, etc. that flows into the second water passage section 2e flows in the extension direction of the second water passage section 2e, that is, in the longitudinal direction, and is drained into a river, sewer, etc. from a discharge pipe (not shown) provided at the discharge end. In this embodiment, the "longitudinal direction" corresponds to the "predetermined drainage flow direction" in the claims.

Next, an example in which the drainage ditch unit 1 is installed on a bridge B will be described with reference to FIG. 4. The bridge B has a roadway D installed in the center in a direction intersecting with the extension direction of the bridge, ground guards G installed on both sides of the roadway D in the intersecting direction, and a shoulder S installed between the roadway D and the ground guards G, and the drainage ditch unit 1 is installed on the shoulder S. In addition, the upper surface of the roadway D is inclined so that it is gradually positioned lower as it approaches the shoulder S. As a result, rainwater, etc. flows from the roadway D to the shoulder S side, and is then introduced into the drainage ditch unit 1 through the drainage holes 3c and drained.

In the example shown in Figure 4, automobiles and the like normally travel on the roadway D, so automobiles and the like travel over the drainage ditch unit 1 installed on the roadside S only in emergencies (for example, when an emergency vehicle such as an ambulance travels on the roadside S).

On the other hand, in the example shown in FIG. 5 where the drainage ditch unit 1 is temporarily installed on bridge B (for example, in the case of repair work on bridge B, or in the case of bridge construction where construction is carried out on each side of the upper and lower lanes), unlike the example shown in FIG. 4, the drainage ditch unit 1 and both sides of it are set as roadways D. Therefore, automobiles and the like frequently run over the drainage ditch unit 1. Note that in this embodiment, the drainage ditch unit 1 installed on bridge B is also used when it is temporarily installed during repair work, or when the drainage ditch unit 1 temporarily installed during bridge construction to construct bridge B is installed on bridge B.

In the example shown in FIG. 5, for example, when a relatively heavy large truck or the like runs over the drainage groove unit 1, a relatively large load acts from above on the top wall 3a of the guard plate 3. The load is transmitted from the top wall 3a of the guard plate 3 to the bottom wall 2a of the water flow plate 2 by the round support 3d and the rib 3e, and is received by the bottom wall 2a. As a result, even if a large truck or the like runs over the drainage groove unit 1, the top wall 3a of the guard plate 3 is prevented from being deformed by the load caused by the running. In this embodiment, even if the wheels of a large truck or the like pass over or around the drainage hole 3c, the load caused by the running is reliably transmitted from the top wall 3a to the bottom wall 2a by the round support 3d arranged close to the drainage hole 3c, so that deformation around the drainage hole 3c in the top wall 3a is prevented.

Next, the anti-slip layer L provided on the upper surface of the top wall portion 3a of the guard plate 3 will be described with reference to Figures 6 to 10. Note that the anti-slip layer L is omitted in Figure 1 for ease of explanation.

The anti-slip layer L is formed by applying a synthetic resin paint (e.g., acrylic paint) or by spraying a thermal spray material (e.g., aluminum and magnesium). This makes the upper surface of the top wall portion 3a of the guard plate 3 more slip-resistant than when the anti-slip layer L is not provided. This makes it possible to prevent the wheels of an automobile or the like running on the guard plate 3 from slipping. Note that Figs. 6 and 7 show a comparative example, and Figs. 8 to 10 show this embodiment.

The anti-slip layer L can increase the slip resistance, but has the property of impeding the flow of liquids such as rainwater. Therefore, if the anti-slip layer L is provided on the entire upper surface of the top wall portion 3a as in the comparative example shown in Figure 6, the anti-slip layer L may impede the flow of rainwater and the like from the roadway D to the drainage hole 3c of the guard plate 3 as shown in Figure 7, which may deteriorate the drainage performance of the drainage groove unit 1.

In contrast, in this embodiment, as shown in FIG. 8, the upper surface of the top wall portion 3a of the guard plate 3 is provided with a plurality of first regions A1 in which an anti-slip layer L is provided, and a plurality of second regions A2 in which the anti-slip layer L is not provided. Since the second regions A2 are not provided with the anti-slip layer L, rainwater and the like flows through them more easily than the first regions A1. In this embodiment, the area of the first regions A1 is set to be smaller than the area of the second regions A2.

The first area A1 and the second area A2 are substantially rectangular in plan view and are arranged alternately along the longitudinal direction. The second area A2 is arranged to extend in the transverse direction and horizontally so as to connect the drainage holes 3c to the periphery R on both sides of the transverse direction of the top wall portion 3a.

When the drainage ditch unit 1 is installed on the shoulder S of a bridge B, as shown in FIG. 9, rainwater, etc. that reaches the periphery R on one side of the top wall portion 3a in the intersecting direction from the roadway D flows smoothly through the second area A2 to the drainage hole 3c. This improves the drainage performance (water collection performance) of the drainage ditch unit 1 compared to the comparative example (see FIG. 6 and FIG. 7) in which the anti-slip layer L is provided on the entire upper surface of the top wall portion 3a.

In addition, when the drainage ditch unit 1 is temporarily installed on a bridge B, as shown in FIG. 10, rainwater and the like that reaches the periphery R on one side of the crossing direction and the periphery R on the other side of the crossing direction of the top wall portion 3a from both sides of the crossing direction of the drainage ditch unit 1 flows smoothly through the second area A2 to the drainage hole 3c. This improves the drainage performance of the drainage ditch unit 1 compared to the above comparative example.

As described above, according to this embodiment, the anti-slip layer L provided in the first area A1 on the upper surface of the guard plate 3 increases the slip resistance, so that it is possible to prevent automobiles, etc. from slipping when they pass over the guard plate 3. In addition, the second area A2 provided to connect the upper surface periphery R of the guard plate 3 and the drainage hole 3c does not have the anti-slip layer L, so rainwater, etc. flows more easily through it than through the first area A1. In other words, rainwater, etc. that reaches the upper surface periphery R of the drainage groove unit 1 from the roadway D of the bridge B flows smoothly through the second area A2 on the upper surface of the drainage groove unit 1 to the drainage hole 3c. This makes it possible to prevent the drainage performance of the drainage groove unit 1 from deteriorating.

For example, when the drainage ditch unit 1 is installed on the shoulder S of the bridge B in a position where the drainage flow direction and the extension direction of the bridge B are approximately the same, rainwater, etc. on the roadway D of the bridge B will flow horizontally toward the drainage ditch unit 1 in a direction that intersects with the drainage flow direction of the drainage ditch unit 1. Here, the second area A2 is provided on the upper surface of the guard plate 3 along approximately the same direction as the rainwater, etc. flows into the drainage ditch unit 1, so that the rainwater, etc. on the roadway D of the bridge B will flow smoothly through the second area A2 to the drainage hole 3c. This prevents the drainage performance of the drainage ditch unit 1 from deteriorating.

In addition, since the first area A1 and the second area A2 are arranged alternately along the drainage flow direction, it is possible to prevent, for example, the second area A2 from being arranged biased toward the upstream or downstream side of the drainage flow direction. This makes it possible to reliably prevent automobiles and the like from slipping when passing over the drainage groove unit 1 along the drainage flow direction.

In addition, even if a truck passes over the guard plate 3 and a relatively large load acts on the guard plate 3 from above, the load is transmitted to the bottom wall portion 2a via the round support portion 3d and the rib 3e, and can be received by the bottom wall portion 2a. This makes it possible to prevent the guard plate 3 from being deformed.

In addition, when rainwater, etc. introduced into the first water passage section 2d through the drainage hole 3c passes between the ribs 3e provided between the first water passage section 2d and the second water passage section 2e and flows into the second water passage section 2e, fallen leaves and other debris contained in the rainwater etc. are caught by the ribs and collected. This makes it possible to prevent debris from entering the second water passage section 2e, and prevents the drainage performance of the drainage groove unit 1 from deteriorating due to debris accumulating in the second water passage section 2e.

For example, when the guard plate 3 is removed from the drainage groove unit 1, the rib 3e separating the first water passage portion 2d and the second water passage portion 2e is no longer present on the water flow plate 2, so that the rib 3e is prevented from getting in the way when cleaning the water flow plate 2 of the drainage groove unit 1.

For example, when a car or the like passes over the guard plate 3, even if the wheels of the car or the like pass over the drainage hole 3c, the load of the car or the like is transmitted to the bottom wall portion 2a by the round support portion 3d, and the load is received by the bottom wall portion 2a. This makes it possible to prevent the surrounding area of the drainage hole 3c in the guard plate 3 from being deformed by the load of the car or the like.

In this embodiment, the drainage ditch unit 1 is described as being installed or temporarily installed on bridge B, but the drainage ditch unit 1 may also be installed or temporarily installed on roads other than bridge B, such as viaducts, underpasses, tunnels, and streets.

In addition, in this embodiment, an example has been described in which the drainage ditch unit 1 is installed or temporarily installed on the shoulder S of the bridge B in a position in which its longitudinal direction coincides with the extension direction of the bridge B, but the drainage ditch unit 1 may also be installed or temporarily installed on the bridge B in a position in which its longitudinal direction extends horizontally, intersecting the extension direction of the road of the bridge B, etc.

In addition, in this embodiment, the drainage groove unit 1 has a generally rectangular shape in plan view, but it may have a shape other than a generally rectangular shape, such as a generally square shape in plan view.

In addition, in this embodiment, an example has been described in which the drainage ditch unit 1 is temporarily installed on a bridge B and is set on a roadway D, but the drainage ditch unit 1 may also be set on a sidewalk, a bicycle pedestrian path, or a bicycle-only lane. In this case, the anti-slip layer L can ensure the drainage performance of the drainage ditch unit 1 while reliably preventing pedestrians and bicycles from slipping.

In addition, in this embodiment, an example has been described in which the longitudinal direction of the drainage groove unit 1 coincides with the "predetermined drainage flow direction." However, as long as the "predetermined drainage flow direction" coincides with the extension direction of the second water passage portion 2e, it is not limited to the longitudinal direction, and may be, for example, a horizontal direction intersecting the longitudinal direction.

In addition, in this embodiment, the first area A1 and the second area A2 are alternately arranged along the longitudinal direction, but as shown in FIG. 11, they may be alternately arranged along the transverse direction.

In addition, in this embodiment, the first area A1 and the second area A2 are generally rectangular in plan view, but may be of any shape other than generally rectangular as long as they are capable of connecting the periphery R of the top wall portion 3a of the guard plate 3 with the drainage hole 3c. For example, the second area A2 may be provided so as to extend radially from the drainage hole 3c toward the periphery R of the top wall portion 3a in plan view.

In addition, in this embodiment, the area of the first region A1 is smaller than the area of the second region A2, but the area of the first region A1 and the area of the second region A2 may be the same, or the area of the first region A1 may be larger than the area of the second region A2.

In addition, in this embodiment, multiple drainage holes 3c are arranged side by side along the longitudinal direction, but they may be arranged side by side along the transverse direction, or only one drainage hole 3c may be provided.

In addition, in this embodiment, the round support portion 3d and the rib 3e are provided to protrude downward from the underside of the guard plate 3, but they may also be provided to protrude upward from the top surface of the water flow plate 2.

In addition, in this embodiment, the ribs 3e are arranged in parallel along the longitudinal direction of the drainage groove unit 1, but they may be arranged in parallel along a direction intersecting the longitudinal direction, or may be arranged in parallel so as to form a roughly arc shape in plan view.

In addition, in this embodiment, a round support portion 3d and a rib 3e are provided, but it is also possible to provide neither one nor both of them.

The present invention is suitable for drainage units that can be installed on roads.

REFERENCE SIGNS LIST 1 Drainage channel unit 2 Water flow plate 2a Bottom wall portion 2d First water passage portion 2e Second water passage portion 3 Guard plate 3c Drainage hole 3d Round support portion (load transmission portion)
3e Rib (load transmission part)
A1: First region A2: Second region L: Anti-slip layer R: Periphery

Claims (7)

A metal drainage groove unit comprising: a water flow plate having a bottom wall portion; and a guard plate provided to cover the water flow plate from above and having drainage holes penetrating in a thickness direction, the metal drainage groove unit being configured to introduce water flowing on a road surface into the inside through the drainage holes as drainage, and to receive the water at the bottom wall portion and to direct the water in a predetermined drainage flow direction,
The upper surface of the guard plate is provided with a first region having an anti-slip layer and a second region not having the anti-slip layer,
A drain groove unit, characterized in that the second region is configured to connect a peripheral edge of the guard plate and the drain hole. The drainage groove unit according to claim 1,
The drainage flow direction of the flow plate is set to be along the extension direction of the road,
The drainage groove unit is characterized in that the second region is arranged to extend horizontally in a direction intersecting the drainage flow direction. The drainage groove unit according to claim 2,
The first region and the second region are each provided in a plurality of regions,
The drain groove unit is characterized in that the first regions and the second regions are alternately provided along the drainage flow direction. The drainage groove unit according to claim 1,
A drainage groove unit characterized in that a load transmission portion is provided on at least one of the upper surface of the bottom wall portion and the lower surface of the guard plate, which transmits a load acting on the guard plate from above to the bottom wall portion. The drainage groove unit according to claim 4,
the load transmission portion includes a plurality of ribs provided at predetermined intervals along an upper surface of the bottom wall portion and dividing the bottom wall portion into a first water passage portion and a second water passage portion;
The drain hole is provided at a position corresponding to the first water passage portion. The drainage groove unit according to claim 5,
The drainage groove unit is characterized in that the rib protrudes downward from the lower surface of the guard plate. The drainage groove unit according to claim 4,
The load transfer portion includes a round support portion extending in the vertical direction and having a cylindrical shape,
A drainage groove unit, characterized in that the round support portion is positioned in close proximity to the drainage hole.

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