CN117536040B - A system suitable for front-end pollutant control in sponge cities - Google Patents

Abstract

The present invention belongs to the technical field of sponge city construction. More specifically, it relates to a system suitable for controlling pollutants at the front end of sponge cities. The system of the present invention includes a crushed stone layer, and the crushed stone layer includes a first crushed stone layer, a second crushed stone layer and a geotextile located between the first crushed stone layer and the second crushed stone layer in the thickness direction; and the crushed stone layer includes a coarse crushed stone area and a fine crushed stone area; the coarse crushed stone area and the fine crushed stone area are distributed at intervals in the plane direction of the crushed stone layer; the coarse crushed stone area is composed of coarse crushed stone of 6-8 cm specification; the fine crushed stone area is composed of fine crushed stone of 0.5-1.5 cm specification; in the thickness direction, the orthographic projection of at least part of the coarse crushed stone area of the first crushed stone layer and the orthographic projection of at least part of the fine crushed stone area of the second crushed stone layer are overlapped; and the orthographic projection of at least part of the fine crushed stone area of the first crushed stone layer and the orthographic projection of at least part of the coarse crushed stone area of the second crushed stone layer are overlapped.

Description

A system suitable for front-end pollutant control in sponge cities

Technical Field

The present invention belongs to the technical field of sponge city construction, and more specifically, relates to a system suitable for controlling pollutants at the front end of a sponge city.

Background technique

Low-impact development of sponge cities refers to the use of multiple means such as source reduction, mid-stream transfer, and terminal storage and regulation during the process of urban development and construction. Through a variety of technologies such as infiltration, retention, storage, purification, use, and discharge, a benign urban hydrological cycle is achieved, the infiltration, storage, purification, utilization, and discharge capabilities of runoff rainwater are improved, and the "sponge" function of the city is maintained or restored.

Urban non-point source pollution includes a series of pollutants such as oil, nitrogen, phosphorus, toxic and harmful substances and urban solid waste gathered on the surface of towns such as streets, commercial areas, squares, parking lots, etc. When it rains, rainwater will wash away the pollutants on the surface, forming non-point source pollution, which will flow into the receiving water bodies of the city through drainage pipes or directly, causing urban water environment pollution. The pollutants carried in the runoff enter the urban water bodies, which not only causes water quality indicators to exceed the standard, but more seriously, the pollutants will affect aquatic organisms and will ultimately affect human health through the food chain. Therefore, it is particularly important to control pollutants in the front end of sponge cities.

Summary of the invention

The technical problem to be solved by the present invention is: in response to the needs of sponge cities, surface rainwater is prone to carry pollutants into urban water bodies when it gathers into the urban drainage system, thereby causing the problem of water quality indicators exceeding the standard. A system suitable for front-end pollutant control in sponge cities is provided.

The purpose of the present invention is to provide a system suitable for controlling pollutants at the front end of a sponge city.

The above-mentioned purpose of the present invention is achieved through the following technical solutions:

A system adapted for controlling pollutants at the front end of a sponge city, comprising a crushed stone layer, wherein the crushed stone layer comprises a first crushed stone layer, a second crushed stone layer and a geotextile located between the first crushed stone layer and the second crushed stone layer in a thickness direction;

Furthermore, the crushed stone layer includes a coarse crushed stone area and a fine crushed stone area; the coarse crushed stone area and the fine crushed stone area are distributed at intervals in the plane direction of the crushed stone layer;

The coarse crushed stone area is composed of coarse crushed stones with a size of 3-5 cm; the fine crushed stone area is composed of fine crushed stones with a size of 0.5-1.5 cm;

In the thickness direction, the orthographic projection of at least part of the coarse crushed stone area of the first crushed stone layer and the orthographic projection of at least part of the fine crushed stone area of the second crushed stone layer are overlapped; and the orthographic projection of at least part of the fine crushed stone area of the first crushed stone layer and the orthographic projection of at least part of the coarse crushed stone area of the second crushed stone layer are overlapped.

For sponge cities, in the actual system operation process, the rainfall is different in different seasons, and there are many types of debris on the road. Especially in the rainy season, a large amount of rainwater can easily carry a large amount of road debris into the underground drainage system, causing poor drainage of the sponge city system and slowing down the infiltration rate of rainwater.

By arranging coarse and fine crushed stones of different specifications in the plane direction, firstly, the rainwater on the road surface can have different infiltration rates in different areas of the road surface. Coarse crushed stones are more likely to form wider diffusion channels with each other, while fine crushed stones are the opposite. However, when fine crushed stones are piled up, more stable channels with longer diffusion paths can be obtained. In this way, when a large amount of rainwater appears on the road surface, the initial rainwater is more likely to carry surface impurities into the coarse crushed stone area, while a relatively small amount of rainwater infiltrates relatively slowly through the fine crushed stone area. In addition, in the plane direction, there will also be relative diffusion of rainwater between the coarse crushed stone area and the fine crushed stone area. In the diffusion process, impurities that are easy to block the drainage system will be intercepted by the fine crushed stone area at the interface between the coarse crushed stone and the fine crushed stone in the plane direction, and the blocked area in the plane direction will not be expanded. When the rainwater infiltrates to a certain depth, the certain rainwater diffusion channels still available in the plane direction can be used to infiltrate the rainwater downward through more channels, and finally a more stable rainwater infiltration capacity is obtained in the plane direction.

In addition, in the thickness direction, the projections of the coarse gravel area and the fine gravel area are overlapped, which can further enable the rainwater that quickly infiltrates from the coarse gravel area to be intercepted and filtered here when the rainwater infiltrates, and rely on the fine gravel areas distributed on both sides of the coarse gravel area in the plane direction to cooperate in interception and filtration. After the rainwater infiltrating the fine gravel area reaches the coarse gravel area, it can infiltrate quickly to avoid rainwater blockage, thereby taking into account both the rapid infiltration and filtration effects of rainwater.

Furthermore, in the plane direction of the gravel layer, in the first gravel layer, the ratio of the area of the coarse gravel area to the area of the fine gravel area is 0.9-1.1, and the coarse gravel area of the second gravel layer and the fine gravel area of the first gravel layer are arranged in one-to-one correspondence, and the orthographic projections of the two are overlapped; the fine gravel area of the second gravel layer and the coarse gravel area of the first gravel layer are arranged in one-to-one correspondence, and the orthographic projections of the two are overlapped.

First, in the plane direction, the area ratio of the coarse crushed stone area and the fine crushed stone area is adjusted. In this way, the infiltration rate and filtration effect of both can be taken into account in the plane direction, especially the fine crushed stone area can better support the coarse crushed stone area structure on both sides in the lateral direction, so that the overall void structure can be stable, avoiding the infiltration rate and filtration effect from decreasing due to the collapse or change of the structure during use.

Furthermore, at the interface between the first crushed stone layer and the second crushed stone layer, the first crushed stone layer forms a depression or a bulge relative to the second crushed stone layer, and the second crushed stone layer forms a corresponding bulge corresponding to the depression of the first crushed stone layer, or the second crushed stone layer forms a corresponding depression corresponding to the bulge of the first crushed stone layer; so that a continuous wavy interface is formed at the interface between the first crushed stone layer and the second crushed stone layer.

A wavy transition interface is formed at the interface between the two, so that a larger contact area can be obtained at the interface between the two, and the infiltration angle of rainwater at the interface is changed. The large contact area ensures a fast infiltration rate, and the adjustment of the infiltration angle, or the change of the rainwater diffusion path here, can enhance the filtering effect at the interface.

Furthermore, the system also includes a matrix layer at the bottom of the gravel layer, and a geotextile sandwiched between the gravel layer and the matrix layer; the matrix layer is composed of river sand with a specification of 1-3 mm.

Furthermore, the thickness of the gravel layer is 18-30 cm; the thickness of the matrix layer is 30-60 cm.

Furthermore, the system also includes a supporting layer at the bottom of the substrate layer, and a geotextile sandwiched between the substrate layer and the supporting layer; the thickness of the supporting layer is 15-20 cm; and the supporting layer is composed of crushed stones with a specification of 3-5 cm.

Furthermore, the system also includes a drain pipe and an overflow pipe located at the bottom of the supporting layer, and the drain pipe and the overflow pipe are connected to the municipal rainwater pipe network.

Furthermore, the system also includes a permeable pavement located on the side of the crushed stone layer away from the matrix layer; the permeable surface is made of either permeable concrete or permeable asphalt.

Furthermore, the system also includes a green space layer located on one side of the matrix layer of the gravel layer; the green space layer is used for planting green plants.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting implementations made with reference to the following drawings:

FIG1 is a schematic diagram showing the interval distribution of the coarse crushed stone area and the fine crushed stone area in the plane direction in a crushed stone layer according to an embodiment;

FIG2 is another schematic diagram showing the spacing distribution of the coarse crushed stone area and the fine crushed stone area in the crushed stone layer in a plane direction according to an embodiment;

FIG3 shows a schematic diagram of a system for controlling pollutants at the front end of a sponge city in a thickness direction according to an embodiment;

Among them, 1-fine crushed stone area, 2-coarse crushed stone area, 3-first crushed stone layer, 4-second crushed stone layer, 5-geotextile, 6-matrix layer, 7-support layer.

Detailed ways

The present invention is further described below with reference to specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

Example 1

A system adapted for controlling pollutants at the front end of a sponge city, comprising a crushed stone layer, wherein the crushed stone layer comprises a first crushed stone layer, a second crushed stone layer and a geotextile located between the first crushed stone layer and the second crushed stone layer in a thickness direction;

Furthermore, the crushed stone layer includes a coarse crushed stone area and a fine crushed stone area; the coarse crushed stone area and the fine crushed stone area are distributed at intervals in the plane direction of the crushed stone layer;

The coarse crushed stone area is composed of coarse crushed stones with a size of 6-8 cm; the fine crushed stone area is composed of fine crushed stones with a size of 0.5-1.5 cm;

In the thickness direction, the orthographic projection of at least part of the coarse crushed stone area of the first crushed stone layer and the orthographic projection of at least part of the fine crushed stone area of the second crushed stone layer are overlapped; and the orthographic projection of at least part of the fine crushed stone area of the first crushed stone layer and the orthographic projection of at least part of the coarse crushed stone area of the second crushed stone layer are overlapped.

Furthermore, in the plane direction of the gravel layer, in the first gravel layer, the ratio of the area of the coarse gravel area to the area of the fine gravel area is 1.0, and the coarse gravel area of the second gravel layer and the fine gravel area of the first gravel layer are arranged in one-to-one correspondence, and the orthographic projections of the two are overlapped; the fine gravel area of the second gravel layer and the coarse gravel area of the first gravel layer are arranged in one-to-one correspondence, and the orthographic projections of the two are overlapped.

Furthermore, at the interface between the first crushed stone layer and the second crushed stone layer, the first crushed stone layer forms a depression or a bulge relative to the second crushed stone layer, and the second crushed stone layer forms a corresponding bulge corresponding to the depression of the first crushed stone layer, or the second crushed stone layer forms a corresponding depression corresponding to the bulge of the first crushed stone layer; so that a continuous wavy interface is formed at the interface between the first crushed stone layer and the second crushed stone layer.

Furthermore, the system also includes a matrix layer at the bottom of the gravel layer, and a geotextile sandwiched between the gravel layer and the matrix layer; the matrix layer is composed of river sand with a specification of 1-3 mm.

Furthermore, the thickness of the gravel layer is 30 cm; the thickness of the matrix layer is 60 cm.

Furthermore, the system also includes a supporting layer at the bottom of the substrate layer, and a geotextile sandwiched between the substrate layer and the supporting layer; the thickness of the supporting layer is 20 cm; and the supporting layer is composed of crushed stones with a specification of 3-5 cm.

Furthermore, the system also includes a drain pipe and an overflow pipe located at the bottom of the supporting layer, and the drain pipe and the overflow pipe are connected to the municipal rainwater pipe network.

Furthermore, the system also includes a permeable pavement located on the side of the crushed stone layer away from the matrix layer; the permeable surface is made of permeable concrete.

Example 2

Compared with Example 1, this embodiment is different in that:

At the interface between the first crushed stone layer and the second crushed stone layer, the first crushed stone layer does not form a depression or a protrusion relative to the second crushed stone layer. In other words, the interface between the two is a flat interface, and other conditions remain unchanged.

Example 3

Compared with Example 1, this embodiment is different in that:

In the plane direction of the gravel layer, in the first gravel layer, the ratio of the area of the coarse gravel region to the area of the fine gravel region is 0.8, and other conditions remain unchanged.

Example 4

Compared with Embodiment 1, the present embodiment is different in that: in the plane direction of the gravel layer, in the first gravel layer, the ratio of the area of the coarse gravel region to the area of the fine gravel region is 1.2, and other conditions remain unchanged.

Comparative Example 1

Compared with Example 1, this comparative example has the following differences:

The first gravel layer is made entirely of coarse gravel, the second gravel layer is made entirely of fine gravel, and the other conditions remain unchanged.

Comparative Example 2

Compared with Example 1, this comparative example has the following differences:

The first gravel layer is made entirely of fine gravel, the second gravel layer is made entirely of coarse gravel, and the other conditions remain unchanged.

According to the above embodiments or comparative examples, a corresponding experimental area is built on the simulated experimental bed, a plastic sieve plate is used at the bottom to facilitate water flow, a crushed stone layer, a geotextile, a matrix layer and a support layer are filled on the experimental bed, and the water supply facilities are a number of Martens flasks, which are connected to the river sand column through a glass communicating vessel and a hose. A control valve is placed on the hose to control the water flow and water stop, and water samples are collected regularly for measurement.

In this experiment, organic and inorganic compounds were added to tap water to simulate road rainwater runoff containing dissolved pollutants. The main pollutants were zinc ions, total phosphorus and petroleum. The following reagents were used: zinc nitrate (addition amount 1.5 mg/L), potassium dihydrogen phosphate (addition amount 0.5 mg/L), castrol motor oil (addition amount 10 mg/L);

Zinc ion, total phosphorus and petroleum were analyzed by atomic absorption spectrophotometry (GB 7475-1987), ammonium molybdate spectrophotometry (GB 11893-1989) and ultraviolet spectrophotometry (GB/T 17378.4-2007) respectively. The water quality after relevant treatment was tested on the 3rd, 9th and 30th day respectively. The specific test results are shown in Table 1-3.

Table 1: Water quality test results on the 3rd day

Table 2: Water quality test results on the 9th day

Table 3: Water quality test results on the 90th day

It can be seen from the test results in Table 1 that the system of the present invention can maintain a stable overall shape during the operation of the sponge city. As the filtration time increases, the system penetration rate remains stable and the filtration effect is also maintained at a high level.

Example 5

A system suitable for controlling pollutants at the front end of a sponge city, comprising an upper and lower crushed stone layer and an intermediate treatment layer, wherein the crushed stone layer comprises a first crushed stone layer, an intermediate treatment layer, a third crushed stone layer, and geotextiles located between the first crushed stone layer and the intermediate treatment layer, and between the intermediate treatment layer and the third crushed stone layer in the thickness direction;

Furthermore, the gravel layer includes an upper and lower gravel layer; the gravel layers are arranged at intervals in the vertical direction, and the arrangement shape can be arranged according to landscape requirements;

The gravel area uses 0-2cm, 3-4cm and 6-8cm well-graded gravel, and the intermediate treatment layer uses 1-3mm river sand or inorganic silicate biological filler, or a combination of the two;

Vertically, the total thickness of the first crushed stone layer and the third crushed stone layer is about 0.4 times that of the intermediate treatment layer, accounting for about 20% to 30% of the height of the entire device, generally not exceeding 30%. Generally speaking, the thickness of the first crushed stone layer and the third crushed stone layer is generally about 5 to 15 cm, respectively, and the intermediate treatment layer is generally 50 cm to 100 cm. It can also be determined after experiments based on actual conditions.

Experiments with simulated rainwater and algae show that: The results are shown in the table below.

The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims (6)

1. A system suitable for controlling pollutants at the front end of a sponge city, characterized in that it comprises a crushed stone layer, wherein the crushed stone layer comprises a first crushed stone layer, a second crushed stone layer and a geotextile located between the first crushed stone layer and the second crushed stone layer in the thickness direction; Furthermore, the crushed stone layer includes a coarse crushed stone area and a fine crushed stone area; the coarse crushed stone area and the fine crushed stone area are distributed at intervals in the plane direction of the crushed stone layer; The coarse crushed stone area is composed of coarse crushed stones with a size of 3-5 cm; the fine crushed stone area is composed of fine crushed stones with a size of 0.5-1.5 cm; In the thickness direction, the orthographic projection of at least part of the coarse crushed stone area of the first crushed stone layer and the orthographic projection of at least part of the fine crushed stone area of the second crushed stone layer are overlapped; and the orthographic projection of at least part of the fine crushed stone area of the first crushed stone layer and the orthographic projection of at least part of the coarse crushed stone area of the second crushed stone layer are overlapped; In the plane direction of the crushed stone layer, in the first crushed stone layer, the ratio of the area of the coarse crushed stone area to the area of the fine crushed stone area is 0.9-1.1, and the coarse crushed stone area of the second crushed stone layer and the fine crushed stone area of the first crushed stone layer are arranged in one-to-one correspondence, and the orthographic projections of the two are overlapped; the fine crushed stone area of the second crushed stone layer and the coarse crushed stone area of the first crushed stone layer are arranged in one-to-one correspondence, and the orthographic projections of the two are overlapped; At the interface between the first crushed stone layer and the second crushed stone layer, the first crushed stone layer forms a depression or a protrusion relative to the second crushed stone layer, and the second crushed stone layer forms a corresponding protrusion corresponding to the depression of the first crushed stone layer, or the second crushed stone layer forms a corresponding depression corresponding to the protrusion of the first crushed stone layer, so that a continuous wavy interface is formed at the interface between the first crushed stone layer and the second crushed stone layer; The system also includes a matrix layer at the bottom of the crushed stone layer, and a geotextile sandwiched between the crushed stone layer and the matrix layer; the matrix layer is composed of river sand with a specification of 1-3 mm. 2. A system suitable for controlling pollutants at the front end of a sponge city according to claim 1, characterized in that the thickness of the gravel layer is 18-30 cm; the thickness of the matrix layer is 30-60 cm. 3. According to claim 1, a system suitable for controlling pollutants at the front end of a sponge city is characterized in that the system also includes a supporting layer at the bottom of the matrix layer, and a geotextile sandwiched between the matrix layer and the supporting layer; the thickness of the supporting layer is 15-20 cm; the supporting layer is composed of crushed stone with a specification of 3-5 cm. 4. A system suitable for front-end pollutant control in sponge cities according to claim 3, characterized in that the system also includes a drain pipe and an overflow pipe located at the bottom of the supporting layer, and the drain pipe and the overflow pipe are connected to the municipal rainwater pipe network. 5. A system suitable for front-end pollutant control in sponge cities according to claim 1, characterized in that the system also includes a permeable pavement located on the side of the gravel layer away from the matrix layer; the permeable pavement is made of either permeable concrete or permeable asphalt. 6. A system suitable for front-end pollutant control in sponge cities according to claim 1, characterized in that the system also includes a green space layer located on the side of the gravel layer away from the substrate layer; the green space layer is used for planting green plants.