Downward concave type greenbelt structure

Abstract

The utility model relates to the technical field of sponge city low-impact development, and particularly discloses a concave green space structure which comprises a terrace, a concave land is formed in the surface of the terrace, a concave green space body is filled in the concave land, an overflow well is arranged at the top end of the concave green space body in a penetrating mode, and an overflow cover is assembled at the top of the overflow well. Blind pipes symmetrically communicate with the positions, close to the bottom end, of the two sides of the overflow well, and the blind pipes penetrate through the downwards-concave green land body and extend to an external drainage system. By laying the anti-seepage layer, the anti-seepage performance of the sunken green space structure can be improved, and the situation that the stability of an underground soil matrix is easily damaged due to rainwater seepage is avoided; by arranging the gravel layer, the first gravel layer and the second gravel layer, double-stage filtration is formed, the double-layer structure achieves the double functions of physical filtration and hydraulic buffering, and the water flow impact force can be effectively reduced. The problems that in a traditional concave greenbelt, cracks are prone to being generated under the action of soil freeze-thaw cycle, the seepage-proofing efficiency of geotechnical cloth is prone to being rapidly attenuated, and water retention, weed suppression and ecological restoration capacities are lacked are solved.

Description

Technical Field

[0001] This utility model belongs to the field of low-impact development technology of sponge cities, specifically, it relates to a recessed green space structure. Background Technology

[0002] The increasing proportion of impervious urban areas has led to a surge in peak stormwater runoff, exacerbating the risks of non-point source pollution loads and combined sewer overflows. This makes traditional drainage systems ill-suited to cope with urban flooding caused by extreme weather events, while also resulting in significant losses of urban rainwater resources. The "sponge city" concept, by simulating the natural hydrological cycle, constructs a distributed stormwater management system centered on "infiltration, retention, storage, purification, utilization, and drainage." Sunken green spaces serve as key micro-units, and runoff control can be achieved through water storage layer design.

[0003] However, existing sunken green spaces generally suffer from the following defects in their protection systems: the shear strength of the single-layer HDPE geomembrane in traditional sunken green spaces is less than 1.5MPa at the joints, making them prone to cracking under soil freeze-thaw cycles; at the same time, ordinary geotextiles, due to their excessive porosity, cause the loss of fine particles, which easily leads to a rapid decline in impermeability, and the resulting foundation erosion has become one of the main causes of road collapse; moreover, the existing surface covering materials for sunken green spaces, such as gravel or bare soil, have a single function, only possessing permeability and lacking water retention, weed suppression, and ecological restoration capabilities.

[0004] Based on this, the present invention provides a recessed green space structure to solve the problems existing in the prior art. Utility Model Content

[0005] In view of this, the main purpose of this utility model is to provide a sunken green space structure to solve the problems of traditional sunken green spaces, such as soil cracking under the action of freeze-thaw cycles, rapid decline in the impermeability of geotextiles, and lack of water retention, weed suppression and ecological restoration capabilities.

[0006] To achieve the above objectives, the technical solution of this utility model is implemented as follows:

[0007] A recessed green space structure includes a ground surface with a recessed area on the surface. The recessed area is filled with a recessed green space body, and an overflow well is provided through the top of the recessed green space body. The top of the overflow well is fitted with an overflow cover with a strip-shaped drainage hole. Blind pipes are symmetrically connected to the two side walls of the overflow well near the bottom. The blind pipes penetrate the recessed green space body and extend to an external drainage system at their top ends.

[0008] In a preferred embodiment, a gravel layer and a fence are arranged sequentially from the inside to the outside around the overflow well. The gravel layer is located at the junction covering the overflow well and the sunken green space, and the fence is located outside the gravel layer.

[0009] In a preferred embodiment, the grid spacing of the fence is ≤20mm.

[0010] In a preferred embodiment, the gravel layer includes a first gravel layer and a second gravel layer, with the second gravel layer disposed on top of the first gravel layer. The first gravel layer consists of gravel of 20-40 mm in size, and the second gravel layer consists of pebbles of 5-10 mm in size.

[0011] In a preferred embodiment, an anchor rod is also provided at the bottom end of the fence, and the lower end of the anchor rod is inserted into the top of the recessed green space body.

[0012] In a preferred embodiment, the upper surface of the recessed green space body has an inverted trapezoidal groove structure, with guide slopes on both sides and a collection platform in the middle, and the overflow well is located at the middle collection platform.

[0013] In a preferred embodiment, the sunken green space body includes a compacted soil base and a planting soil layer, the planting soil layer is laid on the upper side of the compacted soil base, and a covering layer is laid on the planting soil layer, and an impermeable layer is laid between the lower side of the compacted soil base and the depression.

[0014] In a preferred embodiment, a permeable geotextile is also laid between the compacted soil base and the planting soil layer to form an isolation interface.

[0015] In a preferred embodiment, the covering layer includes a ceramsite drainage layer and an ecological weed-suppressing fabric layer, with the ceramsite drainage layer located below the ecological weed-suppressing fabric layer.

[0016] In a preferred embodiment, the impermeable layer comprises, from top to bottom, geotextile one, HDPE geomembrane and geotextile two.

[0017] Compared with the prior art, this utility model provides a recessed green space structure, which has the following beneficial effects:

[0018] 1. By laying an impermeable layer, rainwater infiltration can be effectively blocked, preventing settlement problems caused by sudden changes in the moisture content of the underground soil.

[0019] 2. By setting up a gravel layer, the first and second gravel layers form a two-stage filtration system. This two-layer structure achieves both physical filtration and hydraulic buffering functions, which can effectively reduce the impact force of water flow. At the same time, it avoids local scouring caused by water flow impact at the overflow well inlet. By setting up a fence, the gravel layer can play a certain protective role and prevent gravel loss.

[0020] 3. By designing a sunken green space with a compacted soil base as the structural load-bearing layer, and laying a permeable geotextile on its surface to form an isolation interface, the system effectively prevents the loss of fine particles from the planting soil. The planting soil layer meets the needs of vegetation growth, while the surface cover layer combines water retention and aeration, achieving a UV blocking rate of over 90% while suppressing weed germination. This solves the problems of traditional sunken green spaces, such as soil cracking under freeze-thaw cycles, rapid decline in the impermeability of geotextiles, and lack of water retention, weed suppression, and ecological restoration capabilities. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the overall structure of the recessed green space structure of this utility model;

[0023] Figure 2 This is a front sectional view of the recessed green space structure of this utility model.

[0024] Figure 3 This is a schematic diagram of the overflow well of this utility model;

[0025] Figure 4 This utility model Figure 2 A magnified view of a section at point A in the middle;

[0026] Figure 5 This is a schematic diagram of the structure of the fence of this utility model;

[0027] Figure 6 This is a schematic diagram of the planting soil layer of this utility model;

[0028] Figure 7 This is a schematic diagram of the internal structure of the seepage-proof layer of this utility model;

[0029] Figure 8 This is a schematic diagram of the internal structure of the crushed stone layer of this utility model.

[0030] [Explanation of Key Component Symbols]

[0031] 1. Ground surface; 2. Sunken green space body; 3. Overflow well; 4. Overflow cover; 5. Blind pipe; 6. Crushed stone layer; 7. Fence; 8. Impermeable layer; 9. Anchor bolt; 10. Depression; 21. Compacted soil base; 22. Planting soil layer; 23. Covering layer; 61. First layer of crushed stone; 62. Second layer of crushed stone; 81. Geotextile layer one; 82. Geotextile layer two; 83. Impermeable membrane. Detailed Implementation

[0032] The structure of the recessed green space structure will be further described in detail below with reference to the accompanying drawings and embodiments of this utility model.

[0033] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0034] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments as described in this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0035] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0036] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 9 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0037] As per the instruction manual Figures 1-8 As shown, this utility model provides a technical solution:

[0038] A sunken green space structure includes a ground 1, on the surface of which a depression 10 is formed as a water storage space, which is filled with a sunken green space body 2 composed of planting soil and improved substrate. The upper surface of the sunken green space body 2 has an inverted trapezoidal groove structure, with guide slopes on both sides and a flow collection platform in the middle. An overflow well 3 is installed through the top of the sunken green space body 2 on the platform. An overflow cover 4 with strip-shaped drainage holes is fitted on the top of the overflow well 3 to guide the water flow into the overflow well 3. Two sets of blind pipes 5 are symmetrically connected to the two side walls of the overflow well 3 near the bottom. The blind pipes 5 penetrate the sunken green space body 2 and extend to the external drainage system at the top, forming the main drainage channel of the main structure of the sunken green space body 2. This enables in-layer precipitation within the sunken green space body 2. Therefore, when the water storage in the green space exceeds the design elevation of the water level of the sunken green space body 2, the excess rainwater is diverted into the municipal pipe network through the diversion port of the overflow well 3, thus preventing the water level in the sunken green space body 2 from being too high and damaging the structure of the sunken green space body 2.

[0039] In a preferred embodiment, such as Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5As shown, the overflow well 3 is surrounded by a double-layer protective structure: the outer layer is a stainless steel fence 7, which is fixed to the surface of the collection platform of the concave green space body 2. The fence spacing is ≤20mm, and it effectively intercepts solid impurities with a diameter ≥25mm. The inner layer is filled with a graded crushed stone layer 6, which is laid with crushed stone of 5-20mm continuous particle size and is 150-200mm thick. It is located at the junction of the overflow well 3 and the concave green space body 2. When rainwater flows, the fence 7 blocks surface silt and large debris, and the crushed stone layer 6 removes more than 70% of suspended solids and organic debris from the water flow through physical interception and pore adsorption, preventing the overflow system from clogging. The surface of the blind pipe 5 has several guide holes, and the surface of the blind pipe 5 is covered with a permeable geotextile to prevent soil particle loss while guiding the flow. All components work together to achieve rainwater purification, storage, and safe discharge functions.

[0040] Specifically, an anchor rod 9 is installed at the bottom of the fence 7, with the lower end of the anchor rod 9 inserted into the top of the recessed green space body 2. The anchor rod 9 facilitates the installation and fixation of the fence 7 on the recessed green space.

[0041] In a preferred embodiment, such as Figure 1 , Figure 2 , Figure 6 , Figure 7 and Figure 8 As shown, the sunken green space body 2 includes a compacted soil base 21 and a planting soil layer 22. The planting soil layer 22 is laid on the upper side of the compacted soil base 21, and a covering layer 23 is laid on the planting soil layer 22. An impermeable layer 8 is laid between the lower side of the compacted soil base 21 and the depression 10.

[0042] In the above description, the impermeable layer 8 is laid between the bottom surface of the compacted soil base 21 and the foundation of the depression 10, effectively preventing rainwater infiltration and erosion of the foundation soil. The compacted soil base 21 is formed by layered compaction of graded crushed stone, with a compaction degree of ≥95%, serving as a structural load-bearing layer. Its surface is covered with permeable geotextile to form an isolation interface, preventing the loss of fine particles from the planting soil layer 22. The planting soil layer 22 is composed of garden soil, humus, and slow-release fertilizer particles in a volume ratio of 6:3:1, with a thickness of 200-300mm, meeting the needs of vegetation growth while maintaining a porosity of ≥35%. The surface covering layer 23 adopts a two-component structure: the lower layer is a 50mm thick expanded clay drainage layer with a particle size of 10-20mm, which has both water retention and air permeability functions; the upper layer is laid with an environmentally friendly ecological weed suppressing fabric, with a photocatalytic self-cleaning coating on the surface, which inhibits weed germination while achieving an ultraviolet blocking rate of over 90%.

[0043] Specifically, the impermeable layer 8 comprises, from top to bottom, geotextile one 81, HDPE geomembrane 83, and geotextile two 82. Geotextile one 81 is made of 200g / m² short-fiber needle-punched nonwoven geotextile and serves as the protective layer for the geomembrane. The middle layer is a 1.5mm thick HDPE smooth geomembrane 83 with a longitudinal and transverse tensile strength ≥20MPa, meeting the requirements for puncture resistance and aging resistance. The bottom layer, geotextile two 82, is made of 300g / m² long-filament woven geotextile and is integrally formed with the geomembrane through a thermal bonding process. This structure effectively blocks rainwater infiltration and prevents settlement problems caused by sudden changes in the moisture content of the underground soil.

[0044] In a preferred embodiment, such as Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 8 As shown, the crushed stone layer 6 comprises, from bottom to top, a first crushed stone layer 61 and a second crushed stone layer 62. The first crushed stone layer 61 uses basalt crushed stone with a particle size of 20-40mm and a thickness of 150mm, whose high porosity (40%-45%) forms the main seepage channels. The second crushed stone layer 62 uses natural pebbles with a particle size of 5-10mm and a thickness of 50mm, forming a secondary filtration barrier through small-diameter particles. A permeable geotextile is laid between the two layers to form an interface isolation, preventing fine particle migration and gradation instability.

[0045] As described above, this dual-layer structure achieves both physical filtration and hydraulic buffering functions: the large-pore structure of the first layer of crushed stone 61 can trap suspended solids with a diameter ≥5mm, while reducing rainwater flow velocity to 0.3-0.5m / s; the second layer of crushed stone 62, through fine particle gradation, creates Darcy flow conditions, effectively removing more than 80% of impurities with a particle size of 0.5-5mm. The eddy zone formed at the interface between the two layers enhances the particle settling effect, and combined with the adsorption effect of the pebbles surface, the SS removal rate is increased by 35% compared to the single-layer crushed stone structure, while avoiding local scouring caused by water flow impact at the inlet of the overflow well 3.

[0046] The implementation principle of the recessed green space structure described in this utility model includes:

[0047] Step 1: Foundation treatment and construction of the impermeable layer

[0048] Step 1.1: Excavate depression 10 according to the design elevation, level and compact the base, with a compaction degree ≥90%; lay geotextile 282 on the base, and use hot air welding method to form a closed system with the seepage prevention layer on the side wall of depression 10;

[0049] Step 1.2: Lay HDPE geomembrane 83 on geotextile 2 82, and weld the joints using a double-track hot melt welding machine. The weld strength should not be less than 80% of the parent material. After welding, perform air pressure testing to ensure that the leakage rate is ≤0.5 per 100m. 2；

[0050] Step 1.3: Cover with geotextile 81 as a protective layer, and fix it with U-shaped nails at 500mm intervals, with a nail length ≥150mm. After the impermeable layer 8 is constructed, conduct a 48-hour water storage test. The leakage rate is ≤0.5L / (s·ha) to be considered qualified.

[0051] Step 2: Structural layer construction and equipment installation

[0052] Step 2.1: Backfill graded crushed stone in layers on the impermeable layer 8 to the design elevation, with each layer having a loose thickness of ≤300mm. Compact the soil using a vibratory roller to form a compacted soil base 21, with a surface flatness deviation of ≤±20mm.

[0053] Step 2.2: Pre-bury blind pipe 5 according to the design slope (i=1%-2%), wrap the pipe with permeable geotextile, and connect the outlet end of blind pipe 5 to the municipal drainage network with a socket rubber ring, and perform waterproof sealing treatment at the connection.

[0054] Step 2.3: Install the precast concrete overflow well 3, and fill the gap between the well wall and the compacted soil base 21 with medium sand and vibrate it to ensure compaction. The top elevation of the overflow well 3 should be 20-30mm lower than the collection platform, and graded crushed stone should be laid around the well to form a filter layer.

[0055] Step 2.4: Lay a double layer of crushed stone 6: First, lay a layer of crushed stone 61 (20-40mm crushed stone), 150mm thick, level it manually, and then lay a permeable geotextile; then lay a second layer of crushed stone 62 (5-10mm pebbles), 50mm thick, and lightly tamp the surface with a wooden rammer to compact it.

[0056] Step 3: Functional layer construction and vegetation restoration

[0057] Step 3.1: Lay the planting soil layer 22 on the gravel layer 6. Use a rotary tiller to mix garden soil, humus, and slow-release fertilizer. After mixing evenly, spread the mixture to the designed thickness, controlling the bulk density at [value missing]. 1.2-1.4g / cm3 .

[0058] Step 3.2: Install stainless steel fence 7. The foundation is made of C20 concrete cast in place, and the anchor bolt torque is ≥80 N·m. The top elevation of fence 7 should be 50 mm higher than the surface of the planting soil layer 22 to prevent direct erosion by mud and sand.

[0059] Step 3.3: Cover the surface with a layer of humus and leaves 23, with a uniform thickness controlled at 40±5mm, and spray with EM bacterial agent (effective live bacteria count ≥200 million / mL) for biological activation treatment.

[0060] Step 3.4: Select flood-resistant native varieties for vegetation planting, use hydroseeding technology for construction, cover with non-woven fabric to retain moisture after sowing, maintain for ≥28 days, and only accept and deliver after the survival rate meets the standard.

[0061] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the scope of protection of the present utility model.

Claims

1. A sunken green structure comprising a terrace (1) having a sunken ground (10) formed on the surface thereof, characterized in that, The concave ground (10) is filled with a sunken green body (2), a top end of the sunken green body (2) is provided with an overflow well (3), the overflow well (3) is provided with an overflow cover (4) with a strip-shaped water outlet hole at the top, and blind pipes (5) are symmetrically connected to both side walls of the overflow well (3) near the bottom end, the blind pipes (5) penetrate the sunken green body (2) and extend to an external drainage system at the top end.

2. A depressed green structure as claimed in claim 1, wherein, The overflow well (3) is provided with a gravel layer (6) and a fence (7) from inside to outside in sequence, the gravel layer (6) is located at a joint position of the overflow well (3) and the sunken green body (2), and the fence (7) is located outside the gravel layer (6).

3. A depressed green structure as claimed in claim 2, wherein, The fence (7) has a grid spacing of less than or equal to 20 mm.

4. A depressed green structure as claimed in claim 2, wherein, The gravel layer (6) comprises a first gravel layer (61) and a second gravel layer (62), the second gravel layer (62) is arranged on the top of the first gravel layer (61), the first gravel layer (61) is 20-40 mm gravel, and the second gravel layer (62) is 5-10 mm pea stone.

5. A depressed green structure as claimed in claim 2, wherein, An anchor rod (9) is further arranged at the bottom end of the fence (7), and the lower end of the anchor rod (9) is inserted into the top end of the sunken green body (2).

6. A depressed green structure as claimed in claim 1, wherein, An upper surface of the sunken green body (2) is in an inverted trapezoidal groove structure, both sides form a flow guide slope surface, and a middle part forms a flow collection platform, and the overflow well (3) is located at the middle flow collection platform.

7. A depressed green structure as claimed in claim 1, wherein, The sunken green body (2) comprises a compacted soil base (21) and a planting soil layer (22), the planting soil layer (22) is arranged on the upper side of the compacted soil base (21), a cover layer (23) is arranged on the planting soil layer (22), and a seepage prevention layer (8) is arranged between the lower side of the compacted soil base (21) and the concave ground (10).

8. A depressed green structure as claimed in claim 7, wherein, A water permeable geotextile is further arranged between the compacted soil base (21) and the planting soil layer (22) to form an isolation interface.

9. A depressed green structure as claimed in claim 7, wherein, The cover layer (23) comprises a ceramsite drainage layer and an ecological weed control cloth layer, and the ceramsite drainage layer is located on the lower side of the ecological weed control cloth layer.

10. A depressed green structure as claimed in claim 7, wherein, The seepage prevention layer (8) comprises geotextile one (81), an HDPE seepage prevention film (83), and geotextile two (82) from top to bottom.

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