Subsidence green land structure suitable for near taihu lake basin and construction method

Abstract

This invention relates to a sunken green space structure and construction method suitable for the Taihu Lake basin. The sunken green space structure includes a sunken green space and a water quality control overflow well installed in the sunken green space. The sunken green space includes: a basic impermeable layer; a graded crushed stone drainage layer installed on the basic impermeable layer; a modified soil filter layer installed on the graded crushed stone drainage layer; a planting soil layer installed on the modified soil filter layer; and a water storage layer installed on the planting soil layer. This application solves the long-term waterlogging problem caused by slow soil infiltration and high groundwater level in the Taihu Lake basin from the root by the synergistic effect of the basic impermeable layer isolating high groundwater backflow and the perforated blind pipe forcibly draining infiltrated rainwater. By forming a negative pressure zone to actively induce infiltration, it actively overcomes the natural limitation of poor clay permeability and ensures the applicability of the system in this area.

Description

Technical Field

[0001] This invention relates to the field of sponge city technology, specifically to a method for constructing and building sunken green spaces suitable for the Taihu Lake basin. Background Technology

[0002] Sunken green spaces are one of the important "infiltration, retention, storage, purification, utilization, and drainage" technical measures in the construction of sponge cities. By designing green spaces to be lower than the elevation of surrounding roads or squares, they effectively collect, infiltrate, and purify rainwater runoff, replenish groundwater, and alleviate urban flooding. However, the application of sunken green spaces in the Taihu Lake basin faces unique technical challenges: the groundwater level in this area is high, and the soil is mainly clay and silty clay with poor natural permeability.

[0003] Traditional sunken green spaces are prone to prolonged water accumulation during the rainy season, leading to root rot, functional failure of plants, and even turning them into sewage pits.

[0004] Therefore, how to prevent long-term water accumulation in sunken green spaces under the conditions of high groundwater level and low permeability soil in the Taihu Lake basin, and how to achieve long-term stable operation, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to overcome the defects of the prior art and provide a sunken green space structure and construction method suitable for the Taihu Lake basin, solving the problem that sunken green spaces in the prior art are prone to water accumulation and functional failure under the conditions of high groundwater level and low permeability soil in the Taihu Lake basin.

[0006] To achieve the above objectives, the present invention provides a sunken green space structure suitable for the Taihu Lake basin, comprising a sunken green space and a water quality control overflow well disposed within the sunken green space; the sunken green space includes: Basic seepage prevention layer; A graded crushed stone drainage layer is set on the basic impermeable layer; An improved soil filter layer is disposed on the graded crushed stone drainage layer; A planting soil layer set on the improved soil filter layer; A water storage layer is set on the planting soil layer; The graded crushed stone drainage layer is equipped with a perforated blind pipe for forcibly draining infiltrated rainwater, and the perforated blind pipe is connected to the water quality control overflow well. The basic seepage-proof layer and the perforated blind pipe together form a combined structure of seepage prevention and active drainage. The basic seepage-proof layer is used to block the path of groundwater entry, and the perforated blind pipe is used to actively lower the water level in the graded crushed stone drainage layer, thereby forming a negative pressure zone below the improved soil filter layer and inducing downward seepage from above.

[0007] By adopting this technical solution, the long-term waterlogging problem caused by slow soil infiltration and high groundwater levels in the Taihu Lake basin is fundamentally solved through the synergistic effect of the basic impermeable layer isolating high groundwater backflow and the perforated blind pipe forcibly draining infiltrated rainwater. By forming a negative pressure zone to actively induce infiltration, the natural limitation of poor clay permeability is actively overcome, ensuring the applicability of the system in the area. At the same time, the six functions of sponge city—infiltration, retention, storage, purification, and drainage—are seamlessly connected and synergistically enhanced in one process, realizing the long-term stable operation of sunken green spaces under the complex conditions of the Taihu Lake basin.

[0008] Furthermore, the improved soil filter layer is composed of the following components by volume percentage: The composition consists of 50%-60% local soil, 10%-20% coarse sand, 10%-15% medium sand, 10%-15% zeolite, and 10%-15% biochar.

[0009] By adopting this technical solution, zeolite efficiently exchanges and adsorbs ammonium nitrogen, while biochar adsorbs phosphate and organic pollutants. The two work together to form a targeted purification capacity specifically for the non-point source pollution characteristics of the Taihu Lake Basin. At the same time, the local soil, coarse sand, and medium sand form a stable skeleton structure, which ensures both structural stability and good permeability.

[0010] Furthermore, the basic geomembrane is an HDPE geomembrane.

[0011] By adopting this technical solution, HDPE geomembranes have excellent seepage prevention performance and durability, and can prevent reverse seepage of groundwater, ensuring long-term operational reliability.

[0012] Furthermore, the burial slope of the perforated blind pipe is ≥0.5%.

[0013] By adopting this technical solution, it is ensured that infiltrated rainwater can be discharged from the system in a timely and smooth manner, thus avoiding water accumulation.

[0014] Furthermore, the water quality control overflow well is located at the end of the sunken green space and has sedimentation and filtration functions.

[0015] By adopting this technical solution, rainwater must undergo both sedimentation and filtration treatment before overflowing and being discharged, thereby controlling the quality of the effluent and ensuring the system's protective effect on the receiving water body.

[0016] Furthermore, the water quality control overflow well is internally equipped with a sedimentation section and a filtration section; wherein, The filter section is filled with at least one of zeolite and ceramsite filter media.

[0017] By adopting this technical solution, the sedimentation section removes suspended particulate matter from rainwater, while the zeolite or ceramic filter media in the filtration section further adsorbs and removes nitrogen and phosphorus pollutants. The sedimentation and filtration are connected in series to form a dual protection of sedimentation and filtration, achieving deep purification of rainwater and enhancing the system's ability to control the quality of effluent.

[0018] This invention also provides a construction method for sunken green space structures applicable to the Taihu Lake basin, comprising the following steps: S1. Lay a basic impermeable layer on the base; S2. Graded crushed stone is laid on top of the basic seepage-proof layer and perforated blind pipes are buried to form a graded crushed stone drainage layer. S3. Backfill the improved soil filter layer above the graded crushed stone drainage layer; S4. Backfill the planting soil layer on top of the improved soil filter layer; S5. Install the water quality control overflow well and connect the perforated blind pipe to the water quality control overflow well; S6. A water storage space is set up above the planting soil layer to form a water storage layer.

[0019] By adopting this technical solution, we can ensure that the design functions can be implemented and guarantee the long-term reliability of the constructed system.

[0020] Furthermore, the slope of the perforated blind pipe in step S2 is controlled to be ≥0.5%.

[0021] By adopting this technical solution, rainwater that has been infiltrated can be discharged from the system in a timely and smooth manner, preventing water accumulation.

[0022] Furthermore, the improved soil filter layer in step S3 consists of the following components by volume percentage: The composition consists of 50%-60% local soil, 10%-20% coarse sand, 10%-15% medium sand, 10%-15% zeolite, and 10%-15% biochar.

[0023] By adopting this technical solution, zeolite efficiently exchanges and adsorbs ammonium nitrogen, while biochar adsorbs phosphate and organic pollutants. The two work together to form a targeted purification capacity specifically for the non-point source pollution characteristics of the Taihu Lake Basin. At the same time, the local soil, coarse sand, and medium sand form a stable skeleton structure, which ensures both structural stability and good permeability.

[0024] Compared with the prior art, the present invention has the following advantages: 1. The basic impermeable layer and perforated blind pipes together form a combined structure of seepage prevention and active drainage. The basic impermeable layer blocks the path of groundwater entry, while the perforated blind pipes actively lower the water level in the graded crushed stone drainage layer. The two work together to form a negative pressure zone below the improved soil filter layer and induce downward seepage from above. From the perspective of fluid mechanics, this actively overcomes the natural limitations of poor clay permeability and high groundwater level in the Taihu Lake basin, avoids long-term water accumulation in green areas, and ensures plant survival and infiltration function.

[0025] 2. The improved soil filter layer uses a specific ratio of local soil, coarse sand, medium sand, zeolite and biochar. Zeolite efficiently exchanges and adsorbs ammonium nitrogen, while biochar adsorbs phosphate and organic pollutants. It is specially designed for the characteristics of non-point source pollution in the Taihu Lake Basin and has a high-efficiency and long-lasting removal capacity for non-point source pollutants such as nitrogen and phosphorus in rainwater. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the sunken green space construction applicable to the Taihu Lake basin according to the present invention; Figure 2 This is a schematic diagram of the construction method for sunken green space structures applicable to the Taihu Lake basin according to the present invention.

[0027] Explanation of the attached diagram labels: 1. Basic seepage prevention layer; 2. Graded crushed stone drainage layer; 21. Perforated blind pipe; 3. Improved soil filtration layer; 4. Planting soil layer; 5. Water storage layer; 6. Water quality control overflow well. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0029] Please see the appendix Figure 1 The present invention provides a sunken green space structure suitable for the Taihu Lake basin, including a sunken green space and a water quality regulation overflow well 6 set in the sunken green space; The sunken green space, from bottom to top, includes a basic impermeable layer 1, a graded crushed stone drainage layer 2, an improved soil filtration layer 3, a planting soil layer 4, and a water storage layer 5; among which, The basic impermeable layer 1 is set at the bottom of the entire sunken green space structure and is made of HDPE geomembrane. This HDPE geomembrane is used to prevent the reverse seepage of high groundwater into the interior of the sunken green space and to isolate the reverse seepage effect of high groundwater.

[0030] The graded crushed stone drainage layer 2 is set above the foundation impermeable layer 1 and is composed of graded crushed stone. A perforated blind pipe 21 is buried in the graded crushed stone drainage layer 2 to force the drainage of infiltrated rainwater. The burial slope of the perforated blind pipe 21 is controlled at ≥0.5%. The graded crushed stone drainage layer 2 and the perforated blind pipe 21 together constitute an active drainage system, which collects the rainwater purified by the upper layer and quickly discharges it to the water quality control overflow well 6.

[0031] The improved soil filter layer 3 is set above the graded crushed stone guide layer 2 and is composed of the following components in volume percentage: 50%~60% local soil, 10%~20% coarse sand, 10%~15% medium sand, 10%~15% zeolite, and 10%~15% biochar.

[0032] The local soil is combined with coarse and medium sand to ensure structural stability and permeability; zeolite is used for efficient exchange and adsorption of ammonium nitrogen; biochar is used to adsorb phosphate and organic pollutants; thus, it can achieve efficient adsorption and retention of nitrogen and phosphorus pollutants in rainwater runoff.

[0033] It should be noted that during construction, the above components should be mechanically mixed evenly in advance according to the volume ratio, and backfilled and compacted in layers to ensure the uniformity of purification efficiency.

[0034] The planting soil layer 4 is set above the improved soil filter layer 3 and is used for planting plants. The planting soil layer 4, together with the plant roots and soil microorganisms, performs primary purification of the initial rainwater, while retaining the initial rainwater and reducing the runoff peak.

[0035] The water storage layer 5 is set above the planting soil layer 4, that is, the water storage space above the surface of the sunken green space; the water storage layer 5 is used to retain initial rainwater, reduce runoff peaks, and provide water for plant growth.

[0036] The water quality control overflow well 6 is located at the end of the sunken green space and is connected to the perforated blind pipe 21. The water quality control overflow well 6 has sedimentation and filtration functions, and its interior is provided with a sedimentation section and a filtration section in sequence. The filtration section is filled with at least one of zeolite and ceramsite filter media. Rainwater flows into the well through the perforated blind pipe 21 and is treated by passing through the sedimentation section and the filtration section in sequence before overflowing and discharging, ensuring that the quality of the effluent is controllable.

[0037] The basic impermeable layer 1 and the perforated blind pipe 21 together constitute a combined structure of impermeability and active drainage. The basic impermeable layer 1 is used to block the path of groundwater entry, and the perforated blind pipe 21 is used to actively lower the water level in the graded crushed stone drainage layer 2, thereby forming a negative pressure zone below the improved soil filter layer 3 and inducing downward seepage from above. The core mechanism is that the barrier of the impermeable membrane and the evacuation effect of the drainage blind pipe form a pressure difference at the bottom of the system that is conducive to downward seepage, actively overcoming the natural limitation of poor permeability of clay. Please see the appendix Figure 2 The present invention also provides a construction method for sunken green space structures applicable to the Taihu Lake basin, comprising the following steps: S1. Lay the foundation impermeable layer 1 on the base; HDPE geomembrane is used; before construction, the substrate should be leveled and compacted to ensure that the geomembrane is laid flat and the overlaps are reliably sealed.

[0038] S2. Graded crushed stone is laid on top of the basic seepage prevention layer 1 and perforated blind pipes 21 are buried to form graded crushed stone drainage layer 2. During construction, the burial slope of the perforated blind pipe 21 should be precisely controlled to be ≥0.5%, which is a basic requirement to ensure active drainage capacity; graded crushed stone should be laid and compacted in layers to ensure the stability and permeability of the drainage layer.

[0039] S3. Backfill the improved soil filter layer 3 above the graded crushed stone drainage layer 2; Before construction, local soil, coarse sand, medium sand, zeolite, and biochar should be mechanically mixed evenly in the following volume percentages: local soil 50%~60%, coarse sand 10%~20%, medium sand 10%~15%, zeolite 10%~15%, and biochar 10%~15%. Then, backfill and compact the mixture in layers to ensure uniform purification efficiency of the improved soil filter layer 3.

[0040] S4. Backfill the planting soil layer 4 above the improved soil filter layer 3; The planting soil layer 4 should be suitable for plant growth, and an appropriate amount of organic matter can be added to promote plant growth; after backfilling, it should be leveled and compacted to create conditions for plant planting.

[0041] S5. Install the water quality control overflow well 6 and connect the perforated blind pipe 21 to the water quality control overflow well 6; During construction, the relative positions of the inlet pipe elevation of the overflow well with the outlet elevation of the perforated blind pipe 21, and the overflow outlet elevation with the designed water storage depth of the water storage layer 5 should be accurately checked to ensure that the water flows along the designed path.

[0042] S6. A water storage space is set above the planting soil layer 4 to form a water storage layer 5; By controlling the elevation difference between the sunken green space and the surrounding ground, a water storage space with the designed water storage depth is formed. The present invention has been described in detail above with reference to the accompanying drawings and embodiments. Those skilled in the art can make various modifications to the present invention based on the above description. Therefore, certain details in the embodiments should not be construed as limiting the present invention, and the scope of protection of the present invention shall be defined by the appended claims.

Claims

1. A sunken greenbelt structure suitable for the Taihu Lake Basin, comprising a sunken greenbelt and a water quality regulating overflow well arranged in the sunken greenbelt; characterized in that, The sunken green space includes: Basic seepage prevention layer; A graded crushed stone drainage layer is set on the basic impermeable layer; An improved soil filter layer is disposed on the graded crushed stone drainage layer; A planting soil layer set on the improved soil filter layer; A water storage layer is set on the planting soil layer; The graded crushed stone drainage layer is equipped with a perforated blind pipe for forcibly draining infiltrated rainwater, and the perforated blind pipe is connected to the water quality control overflow well. The basic seepage-proof layer and the perforated blind pipe together form a combined structure of seepage prevention and active drainage. The basic seepage-proof layer is used to block the path of groundwater entry, and the perforated blind pipe is used to actively lower the water level in the graded crushed stone drainage layer, thereby forming a negative pressure zone below the improved soil filter layer and inducing downward seepage from above.

2. The subsiding green structure suitable for the Lower Great Lakes Basin according to claim 1, wherein, The improved soil filter layer consists of the following components by volume percentage: The composition consists of 50%-60% local soil, 10%-20% coarse sand, 10%-15% medium sand, 10%-15% zeolite, and 10%-15% biochar.

3. The subsiding green structure suitable for the Lake Okeechobee basin according to claim 1, wherein, The basic geomembrane is an HDPE geomembrane.

4. The subsiding green structure suitable for the Lake Okeechobee Basin of claim 1, wherein, The slope of the perforated blind pipe is ≥0.5%.

5. The subsiding green structure suitable for the Lake Okeechobee Basin of claim 1, wherein, The water quality control overflow well is located at the end of the sunken green space and has sedimentation and filtration functions.

6. The subsiding green structure suitable for the Lake Okeechobee Basin of claim 1, wherein, The water quality control overflow well is internally equipped with a sedimentation section and a filtration section; wherein... The filter section is filled with at least one of zeolite and ceramsite filter media.

7. A method for constructing a subsiding green structure according to any one of claims 1 to 6, wherein the method is applied to the Taihu Lake Basin, characterized in that, Includes the following steps: S1. Lay a basic impermeable layer on the base; S2. Graded crushed stone is laid on top of the basic seepage-proof layer and perforated blind pipes are buried to form a graded crushed stone drainage layer. S3. Backfill the improved soil filter layer above the graded crushed stone drainage layer; S4. Backfill the planting soil layer on top of the improved soil filter layer; S5. Install the water quality control overflow well and connect the perforated blind pipe to the water quality control overflow well; S6. A water storage space is set up above the planting soil layer to form a water storage layer.

8. The method of claim 7, wherein the method is adapted for the construction of a subsiding green infrastructure in the Lake Okeechobee watershed. The slope of the perforated blind tube in step S2 is controlled to be ≥0.5%.

9. The method of constructing a subsiding green infrastructure suitable for use in the Lake Okeechobee watershed of claim 7, wherein, The improved soil filter layer in step S3 consists of the following components by volume percentage: The composition consists of 50%-60% local soil, 10%-20% coarse sand, 10%-15% medium sand, 10%-15% zeolite, and 10%-15% biochar.

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