A detention-sedimentation-drainage combined urban road rainwater drainage device and method

Abstract

The present application relates to rainwater drainage technical field, especially to a kind of lag-pure-drainage combined urban road rainwater drainage device and method, including water-permeable pavement, rainwater drainage box culvert, concave greenbelt, kerb opening, biological retention zone, overflow well.Pedestrian walkway uses water-permeable pavement, rainwater drainage box culvert is equipped below water-permeable pavement, rainwater drainage box culvert section is square, and its top plate is evenly holed.Pedestrian walkway and non-motor vehicle lane are greenbelt between using concave greenbelt.Non-motor vehicle lane, motor vehicle lane initial rainwater is discharged into biological retention zone in machine non-isolation zone through kerb opening, and after being detained and purified, it flows into overflow port through the perforated pipe laid at the bottom of biological retention zone, rainwater runoff exceeding the detention capacity of biological retention zone is first discharged into overflow port, overflow port is connected with overflow well through pipeline, rainwater runoff exceeding the drainage capacity of overflow port is discharged into overflow well, and overflow well is connected with rainwater drainage box culvert.The urban road rainwater drainage device and method can effectively control rainwater runoff pollution and relieve urban road waterlogging.

Description

Technical Field

[0001] This invention relates to the field of rainwater drainage technology, specifically to a combined retention-cleaning-drainage urban road rainwater drainage device and method. Background Technology

[0002] With the acceleration of urbanization, the impervious area of ​​cities is increasing, leading to urban flooding incidents caused by extreme rainfall. Meanwhile, stormwater runoff pollution has become one of the main sources of pollutants in urban water bodies. Urban roads, as vital transportation links, typically account for 15-20% of urban construction land, but their stormwater runoff pollution accounts for 50-60% of the total urban stormwater runoff pollution load. Furthermore, because urban roads are generally lower than the surrounding construction land, they are also frequent and severely affected areas of flooding during heavy rainfall. Currently, urban road drainage in my country mainly adopts a direct discharge method of side ditches-storm inlets-pipelines (pumping stations)-receiving water bodies, without considering the control of stormwater runoff pollution, and the design standards for stormwater drainage pipelines are too low (the design return period is generally 3-5 years). Currently, urban road storm drains typically use storm grates to trap fallen leaves and other debris from storm runoff, preventing blockages in drainage pipes. However, these grates are ineffective at controlling particulate matter and dissolved pollutants in storm runoff. Particulate matter, in particular, often causes blockages once it enters the drainage pipes. Furthermore, the green belts adjacent to urban sidewalks are usually planted with trees and shrubs. As these trees age, their roots frequently penetrate the sidewalks, damaging their structure and even hindering normal pedestrian traffic.

[0003] To address the issues of the large amount of water required for irrigation during roadside greenbelt maintenance and the inability to quickly manage severe road flooding during rainy weather, CN115821678A discloses a prefabricated road drainage system. This system includes a greenbelt, road shoulders, planting troughs, and drainage ditches. Rainwater enters the greenbelt through drainage wells, is filtered and purified by the soil and vegetation, and then infiltrates into a water storage layer. Once the rainwater accumulates to a certain height, it is quickly discharged into the drainage ditches. However, this drainage system only involves the greenbelt and drainage pipes, achieving the effect of using accumulated water to irrigate the vegetation in the greenbelt. Simultaneously, it cannot control runoff pollution, causing road flooding. Furthermore, it does not consider drainage methods for other parts of the road or the problem of rapid drainage of road flooding under extreme rainfall conditions, thus having certain limitations. To address these problems, a new type of urban road rainwater drainage structure with functions of rainwater runoff pollution control and rapid discharge of excessive rainwater runoff is proposed. This can effectively reduce rainwater runoff pollution and alleviate urban road flooding. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a combined retention-purification-drainage urban road rainwater drainage device and method, which can intercept and purify initial rainwater from urban roads and quickly discharge rainwater from the road surface under heavy rainfall conditions; at the same time, the sidewalk curbs, rainwater drainage culverts, and sunken green space planting beds can adopt a prefabricated integrated structure, which is convenient for construction and installation.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A combined retention-cleaning-drainage urban road stormwater drainage system includes:

[0007] A permeable pavement surface layer, wherein a graded crushed stone layer and a drainage layer are sequentially arranged below the permeable pavement surface layer, and the graded crushed stone layer and the drainage layer are placed inside the rainwater drainage culvert;

[0008] The rainwater drainage culvert has a top plate supporting the horn on its side wall, and the outer side wall of the rainwater drainage culvert serves as a permeable pavement side wall. The other side wall of the rainwater drainage culvert is connected to a sunken green space "L"-shaped planting bed. The "L"-shaped planting bed and the rainwater drainage culvert are an integrated structure.

[0009] The sunken green space 12 has a structure consisting of a planting layer and a drainage layer from top to bottom. Street trees are planted in the middle of the sunken green space, and the planting position of the street trees should avoid the water collection pipe. The surface layer of the planting soil in the sunken green space should be 15-20cm lower than the sidewalk surface. The sunken green space is equipped with an overflow outlet, and one side of the overflow outlet is connected to a rainwater drainage culvert through a drainage pipe.

[0010] Furthermore, the sidewalk is provided with rainwater drainage culvert inspection wells at intervals. Each inspection well includes a manhole cover and a concrete inner wall. A sedimentation tank is provided below each inspection well. The sedimentation tank is preferably 30-50cm deep, square in shape, and has the same width as the rainwater drainage culvert. The position of the inspection well is aligned with the water collection pipe.

[0011] Furthermore, the rainwater drainage culvert consists of a top plate with permeable holes and a bottom plate. The top plate is placed on a top plate support horn during installation, and the diameter of the permeable holes is smaller than the diameter of the gravel in the drainage layer.

[0012] Furthermore, the permeable pavement graded crushed stone layer uses graded gravel with a particle size of 3-20mm, the drainage layer uses gravel with a particle size of 30-50mm, and the thicknesses of the permeable pavement surface layer, graded crushed stone layer, and drainage layer should be 60-100mm, 300-500mm, and 100-150mm, respectively.

[0013] Furthermore, the recessed green space drainage layer is made of coarse gravel, and the planting layer is filled with planting soil.

[0014] Furthermore, the sunken green space and the sidewalk are separated by concrete barriers, with the upper edge of the concrete barriers flush with the sidewalk. The non-street tree section of the sunken green space uses concrete barriers with perforated bottoms, while the street tree section uses concrete barriers without perforations at the bottom.

[0015] Furthermore, a separation strip is set between the motor vehicle lane and the non-motor vehicle lane. The separation strip is a bioretention strip. The bioretention strip is constructed from top to bottom as a planting soil layer, a filler layer, and a drainage layer. The surface of the bioretention strip should be 10-20cm lower than the road surface. The drainage layer is equipped with perforated pipes. The perforated pipes are connected to the overflow well through pipes. The perforated pipes are wrapped with permeable geotextile.

[0016] Furthermore, the overflow channel is divided into an overflow well and an overflow outlet. The overflow channel is higher than the surface of the bioretention zone and should be lower than the road surface. The overflow outlet is connected to the overflow well through a pipe.

[0017] Furthermore, a curb is provided between the bioretention zone and the motor vehicle lane, and the curb is provided with openings at equal intervals, the openings being rectangular in shape.

[0018] The drainage method of the above-mentioned combined retention-cleaning-drainage urban road stormwater drainage device includes the following steps:

[0019] During rainfall, rainwater infiltrates the permeable pavement layer from the sidewalk, then flows through the graded crushed stone layer and drainage layer before entering the stormwater drainage culvert through permeable holes. Rainwater runoff from the sidewalk surface flows downwards into the sunken green space. The rainwater infiltrates in the sunken green space and collects in the drainage layer. It then flows through permeable holes at the bottom of the concrete retaining wall into the permeable pavement drainage layer, and finally through permeable holes in the top slab of the stormwater drainage culvert into the stormwater drainage culvert itself. During rainfall, the permeable pavement, graded crushed stone layer, drainage layer, and surface space of the sunken green space can retain rainwater. Rainwater exceeding the retention capacity of the sunken green space flows directly into the overflow outlet in the sunken green space, and then flows into the stormwater drainage culvert through pipes. Rainwater runoff from the motor vehicle lanes and non-motor vehicle lanes flows along the road's cross slope into the bioretention zone. Initial rainwater enters the bioretention zone, is intercepted and purified by the planting soil layer and filler layer, and then flows into perforated pipes in the drainage layer before flowing into the overflow well.

[0020] As rainfall progresses, water accumulates on the surface of the bioretention zone. Once the water level reaches the overflow outlet, the rainwater enters the overflow outlet and flows into the stormwater drainage culvert. In light to moderate rain, the water overflows through the overflow outlet; in heavy rain or storms, the water overflows through both the overflow outlet and the overflow well.

[0021] After rainwater enters the overflow well, it flows through the collection pipe into the rainwater drainage culvert.

[0022] In summary, the present invention has at least the following beneficial effects:

[0023] In this invention, the rainwater drainage culvert and the sunken green planting pool on the adjacent sidewalk are designed as a prefabricated integrated unit, which facilitates installation and construction.

[0024] In this invention, concrete slabs are used to separate the sidewalks, sunken green spaces, and non-motorized vehicle lanes, which can effectively prevent the roots of roadside trees from invading the roadbed on both sides.

[0025] In this invention, the rainwater drainage culvert has good drainage capacity and can also store rainwater using its volume.

[0026] In this invention, the initial rainwater from urban roads enters the bioretention zone through the curb opening, is filtered and purified, and then discharged into the rainwater drainage culvert. Rainwater exceeding the retention capacity of the bioretention zone is discharged directly into the rainwater drainage culvert through the overflow outlet and overflow well.

[0027] This invention achieves spatiotemporal hierarchical control of rainwater runoff quality and quantity. Spatially, permeable pavement is used on sidewalks to promote rainwater infiltration and reduce discharge. Rainwater from both non-motorized vehicle lanes and motorized vehicle lanes is discharged into bioretention zones, achieving rainwater retention, purification, and discharge. Temporally, during the initial rainfall phase, the permeable pavement on sidewalks does not generate runoff, and initial rainwater from non-motorized vehicle lanes and motorized vehicle lanes is discharged into the bioretention zones for purification. At peak rainfall, rainwater runoff generated by the permeable pavement is discharged into sunken green spaces, overflowing into rainwater drainage culverts. Rainwater runoff from non-motorized vehicle lanes and motorized vehicle lanes is discharged into rainwater drainage culverts through overflow outlets and overflow wells. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the cross-sectional structure of the present invention (1-1).

[0029] Figure 2 This is one of the 2-2 cross-sectional structural schematic diagrams of the present invention;

[0030] Figure 3 This is a schematic diagram of the planar pipe structure of the present invention;

[0031] Figure 4 This is a schematic diagram of the top plate supporting the horn structure of the present invention;

[0032] Figure 5 This is a schematic diagram of the deposition tank structure of the present invention;

[0033] Figure 6 This is a schematic diagram of the top plate of the rainwater drainage culvert of the present invention;

[0034] Figure 7 This is a schematic diagram of the recessed perforated concrete slab structure for green spaces according to the present invention.

[0035] In the diagram: 1. Permeable pavement surface layer; 2. Permeable pavement graded crushed stone layer; 3. Outer sidewall of rainwater drainage culvert; 4. Drainage layer; 5. Top slab; 6. Top slab supporting horn; 7. Rainwater drainage culvert; 8. Sedimentation tank; 9. Manhole cover; 10. Concrete inner wall; 11. Concrete baffle; 12. Sunken green space; 13. "L"-shaped planting bed; 14. Water collection pipe; 15. Planting soil layer; 16. Filler layer; 17. Curbstone; 18. Overflow well; 19. Perforated pipe; 20. Drainage layer; 21. Permeable hole; 22. Perforated concrete baffle; 23. Sunken green space drainage layer; 24. Overflow outlet; 25. Opening; 26. Pipe; 27. Inspection well; 28. Overflow outlet; 29. ​​Planting layer; 30. Sunken green space drainage pipe. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings, taking the case of permeable bricks used in the permeable pavement surface layer as an example. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0038] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0039] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "configuration" should be interpreted broadly. For example, they can refer to a fixed connection or configuration, a detachable connection or configuration, or an integral connection or configuration. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0040] like Figures 1-7 As shown, the road stormwater drainage structure proposed in this invention includes:

[0041] The permeable pavement surface layer 1 is provided, and a graded crushed stone layer and a permeable pavement drainage layer 4 are arranged sequentially below the permeable pavement surface layer 1. The graded crushed stone layer and the permeable pavement drainage layer 4 are located inside the outer side wall 3 of the rainwater drainage box culvert and above the top plate 5 of the rainwater drainage box culvert. The graded crushed stone layer uses graded gravel with a particle size of 8-16mm, and the drainage layer 4 uses gravel with a particle size greater than 50mm. The thicknesses of the permeable pavement surface layer 1, the graded crushed stone layer, and the drainage layer 4 are 100mm, 500mm, and 100mm, respectively.

[0042] The rainwater drainage culvert 7 has a top plate supporting the bull horn 6 connected to the side wall of the rainwater drainage culvert 7. The outer side wall 3 of the rainwater drainage culvert serves as a permeable pavement side wall, and the other side wall of the rainwater drainage culvert 7 is connected to the sunken green space "L"-shaped planting bed 13. The two inner parts of the "L"-shaped planting bed 13 and the rainwater drainage culvert 7 are prefabricated integrated structures. The upper edge of the side wall of the planting bed is flush with the sidewalk and serves as the non-motorized vehicle lane side curb 17 to restrict the growth of tree roots towards the non-motorized vehicle lane side.

[0043] The sunken green space 12 has a structure consisting of a planting layer 29 and a drainage layer 4 from top to bottom. The drainage layer 4 is made of coarse gravel, and the planting layer 29 is filled with planting soil. Street trees are planted at intervals in the sunken green space 12. The planting position of the street trees should avoid the drainage pipe 14. The surface level of the planting soil in the sunken green space 12 should be 10-15cm lower than the sidewalk surface. An overflow outlet 28 is provided at the top of the sunken green space 12. One side of the overflow outlet 28 is connected to the rainwater drainage culvert 3 through a drainage pipe 30.

[0044] In sunken green spaces between tree-lined sections, non-perforated concrete barriers 11 are used to prevent tree roots from extending into the permeable pavement of the sidewalk and damaging it. In sunken green spaces between non-tree-lined sections, perforated concrete barriers 11 are used to allow rainwater to seep into the permeable pavement drainage layer. The upper edge of the concrete barriers is flush with the sidewalk.

[0045] The rainwater drainage box culvert 7 consists of a top plate 5 with permeable holes 21 and a bottom of the rainwater drainage box culvert. When the top plate 5 is installed, it is placed on the top plate support horn 6, and the opening diameter of the permeable holes 21 is smaller than the diameter of the gravel in the drainage layer 4.

[0046] 27 inspection wells for rainwater drainage box culverts are installed at intervals along the sidewalk, such as... Figure 4 , Figure 5 As shown, the inspection well 27 includes a well cover 9 and a concrete inner wall 10. A sedimentation tank 8 should be installed below the inspection well 27. The sedimentation tank should be 30cm deep, square in shape, and have the same width as the rainwater drainage culvert 7. The inspection well should be aligned with the water collection pipe 14.

[0047] When paving non-motorized vehicle lanes and motorized vehicle lanes, a cross slope is provided, with the slope facing the separation zone between motorized and non-motorized lanes. The cross slope of the road surface should be 1.5% to 2%. When surface runoff occurs, rainwater flows along the slope and into the bioretention zone.

[0048] A separation zone between the motor vehicle lane and the non-motor vehicle lane is set up. The separation zone is a bioretention zone. The bioretention zone is constructed from top to bottom as follows: a planting soil layer 15, a filler layer 16, and a bioretention zone drainage layer 20. The surface of the bioretention zone should be 10-15cm lower than the road surface. The drainage layer 20 is equipped with a transverse perforated pipe 19. The perforated pipe 19 is connected to the overflow well 18 through a pipe 26. The perforated pipe 19 is wrapped with a permeable geotextile.

[0049] The overflow outlet in the bioretention zone is divided into a large rectangular overflow well 18 and an overflow outlet 24. The overflow outlet 28 is higher than the surface of the bioretention zone, and the overflow outlet 24 is connected to the overflow well 18 through one end of the pipe 26.

[0050] A curbstone 17 is provided between the median strip, the non-median strip and the driving lane. Openings 25 are provided at equal intervals on the curbstone 17. The openings 25 are rectangular in shape. The positions of the openings on both sides of the curbstone 17 are not aligned to prevent rainwater from flowing through.

[0051] The slope near the gap in curbstone 17 should be increased to enhance water retention capacity. The gaps on both sides of curbstone 17 should not be aligned to prevent rainwater runoff.

[0052] During rainfall, rainwater seeps into the permeable pavement layer 1 of the sidewalk, collects in the graded crushed stone layer, and then enters the rainwater drainage culvert 7 through the permeable holes 21. Rainwater runoff is generated on the sidewalk surface and flows down into the sunken green space 12. The rainwater seeps into the sunken green space 12 and collects in the drainage layer 4. It then flows into the permeable pavement drainage layer 4 through the permeable holes 21 at the bottom of the concrete baffle 11, and then enters the rainwater drainage culvert 7 through the permeable holes 21. During rainfall, rainwater can be retained by the permeable pavement graded crushed stone layer, drainage layer 4 and the surface space of the sunken green space 12. Rainwater exceeding its retention capacity flows directly into the rainwater drainage culvert 7 through the overflow outlet 28 in the sunken green space 12. Rainwater runoff from the motor vehicle lane and non-motor vehicle lane flows into the bioretention zone along the cross slope of the road. Initial rainwater enters the bioretention zone and is intercepted and purified by the planting soil layer 15 and the filler layer 16. Then it flows into the transverse perforated pipe 19 in the drainage layer 20 of the bioretention zone and then into the overflow well 18.

[0053] As rainfall progresses, water accumulates on the surface of the bioretention zone. Once the water level reaches the overflow point, the rainwater flows directly into the overflow well 18 through the overflow outlet.

[0054] In cases of moderate to heavy rain, the water accumulation situation is as follows: Figure 2 As shown, the accumulated water overflows through overflow outlet 24;

[0055] In the event of heavy rain or storms, the water accumulation situation is as follows: Figure 1 As shown, the accumulated water overflows through overflow outlet 24 and overflow well 18;

[0056] After entering the overflow well 18, the rainwater from the road flows through the collection pipe 14 into the rainwater drainage culvert 7.

[0057] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0058] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A combined retention-cleaning-drainage urban road stormwater drainage device, characterized in that, include: A permeable pavement surface layer (1) is provided below the permeable pavement surface layer (1) in sequence, and a graded crushed stone layer (2) and a permeable pavement drainage layer (4) are provided inside the rainwater drainage culvert (7). The rainwater drainage box culvert (7) has a top plate supporting the bull's horn (6) connected to the side wall of the rainwater drainage box culvert (7). The outer side wall (3) of the rainwater drainage box culvert serves as a permeable pavement side wall, and the other side wall of the rainwater drainage box culvert is connected to the sunken green space "L" shaped planting pool (13). The "L" shaped planting pool (13) and the rainwater drainage box culvert (3) are an integrated structure. The sunken green space (12) is set in the "L"-shaped planting bed (13). The structure of the sunken green space (12) consists of a planting layer (29) and a sunken green space drainage layer (23) from top to bottom. The sunken green space (12) is planted with street trees at intervals. The planting position of the street trees should avoid the water collection pipe (14). The surface of the planting soil in the sunken green space (12) is 15-20cm lower than the sidewalk. The sunken green space (12) is provided with a sunken green space overflow outlet (28). One side of the sunken green space overflow outlet (28) is connected to the rainwater drainage culvert (7) through a drainage pipe (30). The sidewalk is provided with rainwater drainage culvert inspection wells (27) at intervals. Each inspection well (27) includes a well cover (9) and a concrete inner wall (10). A sedimentation tank (8) is provided below each inspection well (27). The sedimentation tank (8) is 30-50cm deep, square in shape, and has the same width as the rainwater drainage culvert (7). The inspection well (27) is aligned with the water collection pipe (14). The rainwater drainage culvert (7) consists of a top plate (5) with permeable holes and a rainwater drainage culvert. The bottom of the drainage culvert is composed of a top plate (5) placed on a top plate support horn (6) during installation, and the diameter of the permeable hole (21) is smaller than the diameter of the gravel in the permeable pavement drainage layer (4); the sunken green space (12) and the sidewalk are separated by a concrete baffle (11), the upper edge of the concrete baffle (11) is flush with the sidewalk, the non-street tree section of the sunken green space (12) uses a concrete baffle (11) with perforated bottom, and the street tree section uses a concrete baffle (11) without perforation at the bottom. Concrete retaining wall (11); a separation strip between the motor vehicle lane and the non-motor vehicle lane is set up. The separation strip adopts a bioretention strip. The bioretention strip is constructed from top to bottom as a planting soil layer (15), a filler layer (16), and a bioretention strip drainage layer (20). The surface of the bioretention strip is 10-20cm lower than the road surface. The drainage layer (20) of the bioretention strip is provided with a perforated pipe (19). The perforated pipe (19) is connected to the overflow well (18) through a pipe (26). The perforated pipe (19) is wrapped with permeable geotextile. An overflow channel is provided in the bioretention zone. The overflow channel is divided into an overflow well (18) and a bioretention zone overflow outlet (24). The overflow channel is higher than the surface of the bioretention zone and lower than the road surface. The bioretention zone overflow outlet (24) is connected to the overflow well (18) through a pipe (26). After the road rainwater enters the overflow well (18), it enters the rainwater drainage culvert (7) through the water collection pipe (14).

2. The combined retention-cleaning-drainage urban road stormwater drainage device according to claim 1, characterized in that: The permeable pavement graded crushed stone layer (2) uses graded gravel with a particle size of 3-20mm, the permeable pavement drainage layer (4) uses gravel with a particle size of 30-50mm, and the thicknesses of the permeable pavement surface layer (1), graded crushed stone layer (2), and drainage layer (4) are 60-100mm, 300-500mm, and 100-150mm, respectively.

3. The combined retention-cleaning-drainage urban road stormwater drainage device according to claim 2, characterized in that: The recessed green space drainage layer (23) is made of coarse gravel, and the planting layer (29) is filled with planting soil.

4. The combined urban road stormwater drainage device according to claim 3, characterized in that: A curb (17) is provided between the bioretention zone and the motor vehicle lane. The curb (17) has openings (25) at equal intervals, and the openings (25) are rectangular in shape.

5. A drainage method for a combined retention-cleaning-drainage urban road stormwater drainage device according to claim 4, characterized in that: During rainfall, rainwater seeps into the permeable pavement layer (1) of the sidewalk, then passes through the graded crushed stone layer (2) and the permeable pavement drainage layer (4) in sequence, and enters the rainwater drainage culvert (7) through the permeable holes (21). Rainwater runoff is generated on the sidewalk surface and flows down to the sunken green space (12). The rainwater seeps down into the sunken green space (12) and collects in the permeable pavement drainage layer (4). It then flows into the permeable pavement drainage layer (4) through the permeable holes (21) at the bottom of the concrete baffle (11) and then into the rainwater drainage culvert (7) through the permeable holes (21) on the top plate (5) of the rainwater drainage culvert. During rainfall, the permeable pavement can be used to make rainwater drainage culvert (7) more efficient. The graded crushed stone layer (2), the permeable pavement drainage layer (4) and the surface space of the sunken green space (12) retain rainwater. Rainwater exceeding the retention capacity of the sunken green space flows directly into the sunken green space overflow outlet (28) in the sunken green space (12), and then flows into the rainwater drainage culvert (7) through the pipe (26). Rainwater runoff from the motor vehicle lane and the non-motor vehicle lane flows into the bioretention zone along the cross slope of the road. Initial rainwater enters the bioretention zone, and after being intercepted and purified by the planting soil layer (15) and the filler layer (16), it flows into the perforated pipe (19) in the drainage layer (20) of the bioretention zone, and then flows into the overflow well (18). As rainfall progresses, water accumulates on the surface of the bioretention zone. Once the water level reaches the overflow outlet, the rainwater enters the overflow outlet and flows into the rainwater drainage culvert (7). In the case of light to moderate rain, the water overflows through the overflow outlet (24) of the bioretention zone. In the case of heavy rain or torrential rain, the water overflows through the overflow outlet (24) of the bioretention zone and the overflow well (18). After the road rainwater enters the overflow well (18), it enters the rainwater drainage box culvert (7) through the water collection pipe (14).

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