JP7776252B1 - Drainage structure with blockage reduction structure for drainage across road embankments - Google Patents

Abstract

A cross-drainage pipe (2) crossing a road embankment (1) is prone to being clogged by foreign objects (4) such as soil and driftwood flowing in from upstream, making it difficult to maintain an adequate drainage function. In particular, a structure is required that prevents the inflow of foreign objects (4) while maintaining the capture performance of a permeable section (7) on the slope (8) of the road embankment (1).
[Solution] The present invention provides a drainage structure (5) comprising multiple horizontally arranged screen members (6) and grooves (9) on the slope (8) of a road embankment (1) upstream of a cross-drainage pipe (2). The screen members (6) are equipped with permeable sections (7) spaced apart according to the flow characteristics of the foreign matter (4), and are structured to separate and capture the fluid and foreign matter (4). Furthermore, the drainage structure (5) is integrally formed at the foot of the slope of the road embankment (1), eliminating the need for additional land acquisition and simplifying maintenance. This invention reduces the impact of blockages in the cross-drainage pipe (2) and provides stable drainage function.
[Selected Figure] Figure 1

Description

This invention relates to a drainage structure that reduces blockages caused by sediment, driftwood, etc. flowing down from upstream in cross-section drainage pipes that cross road embankments. It is a technology that captures foreign matter in a permeable section made up of multiple screen members, efficiently separating the flowing water from the foreign matter and draining it away.

Cross drainage pipes that cross road embankments are installed to ensure the function of drainage against inflows from mountain streams and rivers that the roads cross. However, foreign objects such as sediment and driftwood in the inflowing water from upstream mountain streams and rivers often clog the cross drainage pipes and their interiors, reducing drainage capacity and causing erosion and seepage of the road embankment by the flowing water. Such blockages not only compromise road safety, but also increase the burden of regular maintenance.
Conventional blockage mitigation measures have been proposed, such as the construction of check dams and protective fences to capture foreign objects in upstream streams and rivers.

JP 2017-141568 A (protective fence) JP 2019-157384 A (Erosion control dam) Patent No. 6990474 (protective fence)

However, these methods have the following drawbacks:
When constructing new sabo dams or guard fences, which have been proposed as one of the conventional blockage mitigation measures, in mountain streams or rivers upstream of road embankments, it is necessary to secure additional land for the installation site. Furthermore, because they are installed in rivers or streams upstream of road embankments, maintenance work to check the blockage status and remove foreign objects trapped by the sabo dams or guard fences requires entering the sabo dams or guard fences from the upstream side, which is difficult. This raises concerns about issues such as reduced efficiency in maintenance, the need for additional land acquisition, and increased construction costs.

The present invention aims to solve these problems by providing a drainage structure that can be installed integrally within the foot of a road embankment, while also reducing blockages caused by foreign objects such as sediment and driftwood in cross-drainage pipes that cross road embankments, thereby ensuring stable drainage functions. Specifically, the purpose is to maintain drainage functions by providing a permeable section composed of multiple screen members arranged horizontally upstream, which effectively captures foreign objects such as sediment and driftwood and separates them from flowing water before draining them. Furthermore, after blockage by foreign objects, it is necessary to ensure drainage functions for subsequent flowing water until the captured foreign objects are removed. Furthermore, during maintenance after operation, it is necessary to have a structure that allows for partial replacement of components damaged by collisions with foreign objects, etc.

To solve the above problems, the present invention provides a drainage structure for reducing blockages of cross-drainage pipes and the like that cross road embankments, and is characterized by comprising a permeable section that is located within the road embankment upstream of the cross-drainage pipe and that is arranged along the slope of the road embankment, the permeable section extending in one direction, and having a groove section that communicates with the upstream opening of the cross-drainage pipe and a plurality of screen members that are arranged to block the opening of the groove section.

It is preferable that the screen member has a drainage structure characterized by being arranged transversely to the extension direction of the groove portion.

Furthermore, it is preferable that the screen member has a drainage structure characterized by being arranged horizontally.

Furthermore, it is preferable that the screen member has a drainage structure with replaceable features.

According to the present invention, by installing a drainage structure with horizontally arranged screen members and grooves in the permeable section upstream of a cross-drainage pipe or the like in a road embankment, blockage by foreign objects can be reduced and stable drainage function can be ensured. Furthermore, by providing a permeable section tailored to the flow characteristics of the foreign objects, the foreign objects can be appropriately captured and separated from the flowing water, thereby maintaining drainage function. Furthermore, since the structure can be installed integrally with the foot of the road embankment, additional land acquisition is not required, reducing construction costs. Furthermore, the design allows for the replacement and adjustment of the screen members, facilitating periodic maintenance. Furthermore, the design disperses the flow energy of foreign objects, reducing the load on the entire structure and enabling long-term functionality. Since no additional land acquisition is required, the design can be applied while minimizing environmental impact. The drainage structure of the present invention aims to maintain the drainage function of road embankments, while improving the foreign object capture performance to prevent blockage of the cross-drainage pipe and enable safe and efficient drainage management.

1 is a schematic diagram (a: overall view, b: detailed view) showing the side of a drainage structure to be installed in a road embankment constructed in accordance with the present invention. FIG. 1 is a perspective view showing a drainage structure constructed in the present invention. FIG. 2 is a side view showing the drainage structure constructed in the present invention. FIG. 1 is a front view showing a drainage structure constructed in the present invention. 10A and 10B are detailed views (c: front view, d: cross-sectional view) showing a unit 1 consisting of two sets of screen members in a transmission section constructed in the present invention. 10A and 10B are detailed views (e: front view, f: cross-sectional view) showing a unit 2 consisting of three sets of screen members in the transmission section constructed in the present invention. 10 is a side view showing the positions of anchor pins for joining each unit to a groove in a transmission section constructed in the present invention. FIG. A cross-sectional view showing the connection between the screen member and the groove portion (main body) constructed in the present invention. 10A and 10B are detailed views of the anchor pin constructed in accordance with the present invention (g: state in which each component is separated, h: state in which each component is combined). 10A and 10B are schematic diagrams illustrating an outline of an experiment regarding the influence of differences in the clogging reduction structure according to the present embodiment on the foreign matter capturing function. This is a cross-sectional view showing the drainage structure (i: conventional screen member without grooves, j: proposed screen member with grooves) in an experiment to determine the effect that differences in the blockage reduction structure related to this embodiment have on the foreign object capture function. 10 shows the results of an experiment on the influence of differences in the clogging reduction structure according to this embodiment (whether or not driftwood is mixed in, whether or not a back panel is present in the groove portion) on the foreign object capturing function. 10A and 10B are schematic diagrams showing the effect of the difference in the clogging reduction structure according to this embodiment on the foreign object capturing function (i: conventional screen member without grooves, j: proposed screen member with grooves).

A preferred embodiment of the present invention will be described with reference to the drawings. Note that the embodiment shown below is merely an example, and various other forms are possible within the scope of the present invention.

<Drainage structure configuration>
FIG. 1(a) is a schematic overall view of the side of a drainage structure 5 installed in a road embankment 1 constructed according to the present invention, and FIG. 1(b) is a detailed view thereof. FIG. 2 is a perspective view showing an overview of the drainage structure 5 constructed according to the present invention. FIG. 3 is a side view showing details of the drainage structure 5 constructed according to the present invention. FIG. 4 is a front view showing details of the drainage structure 5 constructed according to the present invention. FIG. 5(c) is a front view of unit 1 (10) consisting of two sets of screen members 6 in the transmission section 7 constructed according to the present invention, and FIG. 5(d) is a cross-sectional view thereof. FIG. 6(e) is a front view of unit 2 (11) consisting of three sets of screen members 6 in the transmission section 7 constructed according to the present invention, and FIG. 6(f) is a cross-sectional view thereof. FIG. 7 is a side view showing in detail the positions of anchor pins 14 for connecting each unit (10, 11) to the groove portion 9 in the transmission section 7 constructed according to the present invention. FIG. 8 is a cross-sectional view showing in detail the connection between the screen member 6 and the groove portion 9 constructed according to the present invention. FIG. 9(g) is a detailed view of the anchor pin 14 constructed in accordance with the present invention, in which each component is separated, and FIG. 9(h) is a detailed view of the component combined.
As shown in Figures 1 and 2, the proposed drainage structure 5 is intended to reduce the blockage of crossing drainage pipes 2, etc. that cross a road embankment 1, caused by foreign objects 4 such as sediment, driftwood, etc. contained in debris flows, etc., flowing down from the upstream of the mountain stream 3 that it crosses. The drainage structure 5, which has an open permeable section 7, is arranged along the slope 8 of the road embankment 1 (the foot of the slope at the bottom end of the embankment) on the upstream side of the crossing drainage pipes 2, etc., and is constructed as an integral structure.
The lower part of the groove 9 in the permeable section 7 is positioned so as not to obstruct the flow in the riverbed of the stream 3 and the bottom of the cross-drainage pipe 2, and the opening range of the permeable section 7 is provided along the direction of the slope 8 up to the height (range) that foreign matter 4 may reach. It is desirable that the cross-sectional width of the open permeable section 7 be approximately the same as the width of the stream 3 immediately upstream.
A trench 9 (main structure) constructed of concrete or the like connects to the upstream opening of the cross-drainage pipe 2 within the permeation section 7, and multiple screen members 6 are arranged across the opening of the permeation section 7 in the extension direction to block it. For maintenance purposes, horizontal arrangement is desirable to allow for replacement of damaged members. Here, the screen members 6 are typically made of steel or other materials and shapes that are not susceptible to damage when struck by a foreign object 4. For versatility and ease of construction, cylindrical or rectangular hollow steel pipes are preferred. Furthermore, the width (outer diameter) of the material for the screen members 6 should be equal to or greater than the particle size of soil and sand (including pebbles and gravel) that are expected not to be blocked by the cross-drainage pipe 2. For ease of construction and versatility, the standard width (outer diameter) of the screen members 6 is approximately 10 cm to less than 30 cm. The installation spacing (net spacing) of the screen members 6 in the horizontal arrangement method should be approximately the width (outer diameter) of the screen members 6.
This allows foreign objects 4 that may block the cross-drain pipe 2 to be captured on the upstream surface of the multiple screen members 6, and separates harmless flowing water, which is then discharged further downstream through the downstream cross-drain pipe 2.

As shown in Figure 3, the drainage structure 5 to be provided is connected to the upstream side of the cross-drainage pipe 2 along the slope 8 of the road embankment 1, and is mainly composed of a permeable section 7 and a trench section 9 installed within the road embankment 1. The drainage structure 5 is installed at a longitudinal and height position that allows for the smooth drainage of flowing water, which has separated foreign matter 4, flowing down from the upstream stream 3 into the downstream cross-drainage pipe 2.

<Configuration of the transmission section>
The transmission section 7 and the screen members 6 installed in the transmission section 7 are combined and joined as unit 1 (10) and unit 2 (11) using a base frame 12 made of steel or the like, and each unit (10, 11) is joined so as to close the transmission section 7 of the main body of the trench section 9. In this case, the combination of unit 1 (10) and unit 2 (11) is selected and joined depending on the required length and height of the transmission section 7. The transmission section 7 is designed to withstand impacts when hit by foreign objects such as soil and driftwood.

<Configuration of unit>
5 and 6, each unit (10, 11) is configured by fixing a plurality of screen members 6 and a frame 12 using mounting brackets 13. Note that anchor pins 14 are used to join the frame 12 and the main body of the groove portion 9.

Furthermore, as shown in Figures 7 and 8, multiple anchor pins 14 are used to join the base 12 and the main body of the groove portion 9. In this case, the number, shape, and arrangement of the anchor pins 14 are designed to withstand impacts such as collisions with foreign objects such as soil and driftwood.

<Anchor pin configuration>
As shown in FIG. 9, the anchor pin 14 is configured by combining a plurality of nuts 17 and washers 16 with an anchor body 15 made of a material having sufficient strength.

Note that the present invention is not limited to the above shapes, and can be freely modified as long as the essential aspects of the present invention are not altered.

<Example>
Next, an example of a drainage structure 5 having multiple screen members 6 and the like will be described. FIG. 10 is a schematic diagram outlining an experiment examining the effect of differences in the drainage structure 5 according to this embodiment on the foreign matter 4 capture function. FIG. 11(i) is a cross-sectional view of the shape of a transmission section 7 composed only of multiple screen members 6 without conventional grooves 9, and FIG. 11(j) is a cross-sectional view of multiple screen members 6 with the proposed grooves 9, in an experiment examining the effect of differences in the drainage structure 5 according to this embodiment on the foreign matter 4 capture function. FIG. 12 shows the results of an experiment examining the effect of differences in the drainage structure 5 according to this embodiment and experimental conditions (presence or absence of driftwood, presence or absence of a back panel for the grooves 9) on the foreign matter 4 capture function. FIG. 13(i) is a schematic diagram illustrating the effect of differences in the drainage structure 5 composed only of screen members 6 without conventional grooves 9 on the foreign matter 4 capture function, and FIG. 13(j) is a schematic diagram illustrating the effect of differences in the drainage structure 5 according to this embodiment on the foreign matter 4 capture function of the proposed screen members 6 with grooves 9.

As shown in Figure 10, assuming a scale of approximately 1/100 of the actual size, a channel 18 (length 1 m, width 10 cm) with a slope θ1 (15 degrees) and a base covered with uniform soil and sand (gravel, diameter d approximately 7 mm, internal friction angle of the soil and sand: 38 degrees) and driftwood (diameter 1.6 mm, length 4 cm, 50 pieces, specific gravity in dry state: approximately 0.75) 20 was created. Water was supplied from upstream of the channel 18 using a pump 19 to erode the soil and sand (gravel) 21, causing a debris flow 22, and the weight of the gravel captured by a drainage structure 5 (blockage mitigation work) installed downstream of the channel 18 and the number of driftwood pieces that flowed downstream were measured. Comparisons were also made with different installation angles θ1 (90 or 45 degrees) for the permeation section 7, multiple screen members 6 (horizontal members), net spacing between the screen members 6 (net spacing ratio to gravel diameter d: 1.5d; 10mm, 1.0d, 2.0d), and cross-sectional shapes for the screen members 6 (cylindrical members), and with different amounts of water supplied from upstream qin. Here, as shown in Figure 11, the effects of the presence or absence of grooves 9 (back panel) in the permeation section 7 were verified. Furthermore, preliminary experiments were conducted to ascertain the effects of differences in the addition of driftwood branches, the number of driftwood pieces added, the installation angle of the permeation section 7, and the gradient of the water channel 18. Each set of conditions was tested three times, and the results were averaged.

Figure 12 shows the change in sediment and driftwood capture rate depending on whether or not the groove 9 (back panel) shown in Figure 11 is installed. As shown in Figure 12, the sediment capture rate was significantly improved when the back panel was installed (groove with driftwood: 97%) compared to when there was no back panel (no groove - with driftwood: capture rate 28%). Observations during the experiment suggest that this is due to the backwater effect and rising effect of the water flow generated immediately upstream of the drainage structure 5 and screen member 6, which are influenced by the water pressure 23 that exists in the space between the screen member 6 and the back panel of the groove 9 in the proposed drainage structure 5, significantly reducing the downstream flow velocity (Figure 13, j). Note that a similar trend was observed when only sediment and water were supplied without driftwood. On the other hand, as shown in Figure 13(i), when there was no groove 9 (back panel), most of the sediment and driftwood 20 contained in the debris flow 22 was not captured, but passed through the screen member 6 (gaps between members) and flowed downstream 24. This is thought to be due to the influence of specific gravity, and the driftwood in particular accumulated at the head of the flow and continued to flow downstream.

As shown by these results, according to the present invention, by installing a drainage structure 5 having a screen member 6 and a groove portion 9 arranged horizontally on the upstream side of the cross drainage pipe 2 in the road embankment 1, it is possible to reduce blockage caused by foreign matter 4 and ensure stable drainage function, and by providing a permeable portion 7 that corresponds to the flow characteristics of the foreign matter 4, it is expected that the foreign matter 4 can be appropriately captured and separated from the flowing water 24, thereby maintaining the drainage function.

1 Road embankment 2 Cross drainage pipe 3 Mountain stream 4 Foreign object 5 Drainage structure 6 Screen member 7 Permeable portion 8 Slope 9 Groove portion 10 Unit 1
11 Unit 2
12 Mounting frame 13 Mounting bracket 14 Anchor pin 15 Anchor body 16 Washer 17 Nut 18 Waterway 19 Pump 20 Sediment, driftwood 21 Erosion 22 Debris flow 23 Water pressure 24 Runoff

Claims (4)

A drainage structure for reducing blockage of a cross drainage pipe that crosses a road embankment over which a mountain stream passes in the direction of flowing downstream from the upstream of the mountain stream ,
A permeable section is provided in the road embankment on the upstream side of the cross-drainage pipe and is arranged along the slope of the road embankment,
A drainage structure characterized in that the permeable section extends in one direction and has a groove section communicating with the upstream opening of the transverse drainage pipe and a plurality of screen members arranged to block the opening of the groove section. The drainage structure described in claim 1, characterized in that the screen member is arranged transversely to the extension direction of the groove portion. The drainage structure described in claim 2, characterized in that the screen member is arranged horizontally. 10. The drainage structure of claim 1, wherein said screen member has replaceable features.