Multi-stage collaborative ecological bank protection structure suitable for water level change area and construction method thereof

Abstract

The invention discloses a multi-stage collaborative ecological bank protection structure suitable for a water level change area and a construction method of the multi-stage collaborative ecological bank protection structure. The multi-stage collaborative ecological bank protection structure sequentially comprises a gradient riprap protection area, a composite collaborative water level change area, a stepped ecological purification area and a slope base protection zone from a water area to a land area, the slope base protection belt is arranged along the slope surface on one side of the stepped ecological purification area, the slope base protection belt comprises a geogrid and biomineralization improved soil, the geogrid is embedded into the soil body of the slope surface, and a urease generating microbial inoculum is mixed in the biomineralization improved soil. According to the invention, a stable, purified and ecological integrated system is formed through slope surface foundation stabilization, onshore sewage interception and intermediate purification, so that the problem of single function of the traditional bank protection is solved, and the onshore and in-water dual pollution control is communicated with the land and water ecological corridor.

Description

Technical Field

[0001] This invention relates to the field of water conservancy engineering and ecological environment restoration technology, and in particular to a multi-level collaborative ecological revetment structure and its construction method suitable for water level fluctuation zones. Background Technology

[0002] The water level fluctuation zone is a transitional zone between aquatic and terrestrial ecosystems, possessing ecological characteristics of both water and land. However, its unique hydrological conditions, including periodic rises and falls in water level and strong scouring by water flow, lead to numerous technical bottlenecks in traditional bank protection. Traditional hard bank protection, such as concrete walls and masonry retaining walls, can meet the requirements for scouring resistance and stability, but they have extremely poor ecological performance, severing the aquatic-terrestrial ecological corridor, failing to provide habitats for animals and plants, and failing to purify pollutants in water bodies and surface runoff. Existing ecological bank protection is mostly a single-function structure, either focusing on ecological planting but lacking stability, or only focusing on structural stability without active purification capabilities, making it difficult to simultaneously address the multiple needs of scouring protection, pollution interception, and habitat construction in the water level fluctuation zone.

[0003] For example, some ecological revetments use stacked single ecological bags or ecological brick masonry, which, while possessing certain ecological benefits, lack effective connection between the ecological bags and the base structure, making them prone to slippage and disassembly when the water level drops. Although some revetments are equipped with rainwater purification modules, they lack coordinated design with the underlying revetment structure, resulting in the inability to achieve targeted replenishment and secondary purification of rainwater after purification. The hydraulic retention time is short, leading to low removal efficiency for difficult-to-treat pollutants such as nitrate nitrogen and heavy metals. At the same time, the habitat design of existing ecological revetments is mostly surface-level, lacking continuous underwater-above-water habitat space, making it difficult to promote biodiversity restoration.

[0004] Therefore, there is an urgent need for a multi-level collaborative ecological revetment structure that can integrate structural stability, active purification function, and continuous ecological corridor. Summary of the Invention The technical problem to be solved by this invention is to provide a multi-level collaborative ecological revetment structure and its construction method suitable for water level fluctuation zones. Through hierarchical collaborative design and active purification mechanism, it achieves the functional synergy of stability, purification and ecology in an integrated manner, and solves the technical problems of traditional revetment such as the contradiction between stability and ecology, low purification efficiency and habitat discontinuity.

[0005] To achieve the above objectives, this application provides a multi-level collaborative ecological revetment structure suitable for water level fluctuation zones. From the water area to the land area, it sequentially includes a gradient riprap protection zone, a composite collaborative water level fluctuation zone, a stepped ecological purification zone, and a slope base protection belt. The slope base protection belt is installed along the slope on the land side of the revetment structure. The slope base protection belt includes geogrid and biomineralized modified soil. The geogrid is installed along the slope and embedded in the biomineralized modified soil. Urease is mixed in the biomineralized modified soil to produce a microbial agent, achieving in-situ solidification of the slope soil through microbial mineralization.

[0006] The gradient riprap protection zone is constructed by layering stones with particle sizes of 25-35cm, 35-45cm, and 45-55cm from bottom to top. The spaces between the stones are filled with permeable polymer mortar with a joint width of 2-3cm. Expansion joints are set every 3-4m, and the expansion joints are filled with a composite structure of asphalt hemp and bentonite waterproofing blanket. The bottom layer of stones is embedded in the slope toe soil to a depth of not less than 1.2m.

[0007] The composite synergistic water level fluctuation zone includes a lower reinforced stabilization layer and an upper composite ecological layer. The lower reinforced stabilization layer is a permeable retaining wall constructed by dry stacking hollow ecological fish nest bricks. The interior of the bricks and the back of the wall are filled with a composite filler of gravel, carbon source filler and biological ceramic particles. The carbon source filler is a mixture of sulfur and limestone particles. Three layers of geotextile filter layer are laid on the land side of the retaining wall, and a 6-10cm thick graded sand cushion layer is sandwiched between adjacent geotextile layers.

[0008] The lower reinforcement and stabilization layer is embedded in the trapezoidal groove at the top of the gradient riprap protection zone. The hollow ecological fish nest brick has a double-layer honeycomb structure. Several nest holes with a diameter of 12-16cm are opened on the front of the brick, and water permeable holes with a diameter of 5-8cm are opened on the back. Bionic protrusions are set on the inner wall of the nest holes.

[0009] The upper composite ecological layer includes ecological bags and connecting buckles. The ecological bags are made of a blend of polyester fiber, coconut fiber and basalt fiber. The bags are filled with a mixed matrix of improved vegetative soil, biochar and water-retaining agent in a mass ratio of 8:1:1. Adjacent ecological bags are fixed between layers and between bags by connecting buckles. The bottom ecological bag is fully embedded and interlocked with the hollow ecological fish nest bricks of the lower reinforcement and stabilization layer through a wedge-shaped interlocking groove.

[0010] The upper composite ecological layer is planted with a mixed community of flood-tolerant aquatic plants, including reeds, cattails, and loosestrife. The improved planting soil is made by mixing garden soil, humus, perlite, vermiculite, and wood ash in a mass ratio of 5:3:1:0.5:0.5, with a pH value of 6.8-7.8 and an organic matter content of not less than 3%.

[0011] The vertical height ratio between the lower reinforcement and stabilization layer and the upper composite ecological layer is 1:2-2.5. Multiple transverse intercepting troughs are set on the slope of the upper composite ecological layer. The intercepting troughs are filled with a mixture of gravel and ceramsite, and the spacing between the intercepting troughs is 2.5-3.5m.

[0012] The stepped ecological purification zone, from top to bottom, includes a surface vegetation layer, an improved topsoil layer, a bio-zeolite composite filter layer, a graded crushed stone diversion layer, and a permeable concrete base layer. Y-shaped permeable diversion pipes are embedded in the graded crushed stone diversion layer, with a spacing of 1.2-1.8m between the permeable diversion pipes. One branch of the permeable diversion pipe at the lower end connects to the upper composite ecological layer, and the other branch extends to the lower reinforcement and stabilization layer. In the bio-zeolite composite filter layer, the volume ratio of biochar to zeolite is 2:1, the particle size is 4-6mm, and the thickness is 10-15cm.

[0013] The surface vegetation layer is planted with a mixed plant community of iris, calamus, canna and black-eyed Susan. A buffer zone with a width of 1.5-2.0m is set around the stepped ecological purification area. The buffer zone is paved with a mixed sod of tall fescue, alfalfa and white clover. The slope of the buffer zone is 1:3.5-1:4.5. The thickness of the permeable concrete base layer is 15-20cm. A construction method applicable to revetment structures includes the following steps: S1. Conduct on-site surveys and mark the normal water level line and historical highest and lowest water level lines. Trim and compact the slope to the design slope ratio of 1:3-1:4. Use a lightweight dynamic penetrometer to test the bearing capacity of the slope soil. S2. Excavate the stepped foundation trench of the gradient riprap protection zone, remove the loose soil and silt, and then build the gradient riprap in layers. Fill the mortar joints with permeable polymer mortar and vibrate to compact them. Set up expansion joints and composite filling structures. S3. Lay a graded crushed stone cushion layer with waterproofing agent above the gradient riprap protection zone, dry-lay hollow ecological fish nest bricks, simultaneously fill composite filler in layers and compact it, and lay three layers of geotextile filter layer and sand cushion layer. S4. Lay the ecological bags from bottom to top, fix them with connecting buckles and lock them to the hollow ecological fish nest bricks, plant the flood-resistant aquatic plant mixed community, and water and maintain them. S5. Construct a stepped ecological purification zone, laying permeable concrete base layer, graded crushed stone diversion layer, biochar-zeolite composite filter layer and improved topsoil in sequence, installing permeable diversion pipes and conducting water flow test, and planting mixed plant communities. S6. Embed the geogrid into the slope soil, lay bio-mineralized improved soil on the upper and lower sides of the geogrid to form a slope base protection zone, lay planting soil on the top slope, and plant drought-resistant herbaceous plants on the planting soil.

[0014] Compared with the prior art, the above-conceptual technical solution conceived in this application has the following beneficial effects: 1. This invention utilizes a gradient riprap protection zone to establish a stable foundation and resist underwater erosion; a composite synergistic water level fluctuation zone to achieve synergistic stability, purification, and ecological functions; a stepped ecological purification zone to intercept land-based pollution and provide targeted replenishment for synergistic purification; and a slope base protection belt to in-situ strengthen the slope soil and supplement stability. Through slope stabilization, land-based pollution interception, and intermediate purification, an integrated system of stability, purification, and ecology is formed, addressing the shortcomings of traditional single-function bank protection while achieving dual pollution control on land and in water, and connecting the water and land ecological corridors. Furthermore, a slope base protection belt is installed on the slope, achieving in-situ solidification of the slope soil through microbial mineralization. Microbial mineralization solves the problem of insufficient soil strength and easy erosion, fundamentally improving the slope soil's resistance to erosion and scouring. The mesh constraint of the geogrid enhances the integrity of the solidified body, preventing it from cracking and falling off under water flow impact, while also providing additional anti-sliding force.

[0015] 2. The biomineralized improved soil in the slope base protection zone of this invention utilizes urease-producing bacteria to induce a microbial calcium carbonate deposition reaction. Through microbial metabolic activities, soil particles are cemented, realizing the transformation from loose soil to a rock-like structure. Microbial mineralization tightly cements the soil with the geogrid, preventing the geogrid from separating from the soil. The geogrid provides a stable mechanical environment for the mineralization reaction, preventing soil particle loss during the reaction process, ultimately forming a slope protection system with internal hard cementation and external firm constraint. 3. This invention employs a multi-layered protection system, consisting of gradient stone embedding, dry-stacked ecological fish nest bricks, and embedded ecological bags, along with auxiliary structures such as expansion joints and intercepting channels, to effectively resist water level fluctuations and water flow erosion. The overall structure exhibits strong stability and is suitable for reservoirs and rivers with significant water level fluctuations.

[0016] 4. This invention utilizes plant root adsorption and denitrification filter layer for active purification, which can efficiently intercept silt, heavy metals, and phosphorus in surface runoff, and actively degrade difficult-to-treat pollutants such as nitrate nitrogen, thus achieving dual pollution control on land and in water.

[0017] 5. This invention constructs a continuous habitat corridor of underwater nests, waterside root systems, and terrestrial vegetation, providing diverse habitats for fish, amphibians, birds, and other species, and significantly enhancing biodiversity.

[0018] 6. This invention creates a natural waterfront landscape by constructing a multi-layered plant configuration, replacing the traditional gray hard wall surface and enhancing the aesthetic appeal of the environment; the core components adopt prefabricated modules and dry-laying technology, which makes construction convenient, minimizes disturbance to the site environment, and has low maintenance costs, combining economic efficiency and ecological sustainability. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.

[0020] Figure 1 This is a schematic diagram of the cross-sectional structure of the revetment structure of the present invention.

[0021] Figure Labels Gradient riprap protection zone 10, trapezoidal trough 11, lower reinforcement and stabilization layer 20, upper composite ecological layer 30, ecological bag 31, connecting buckle 32, stepped ecological purification zone 40, surface vegetation layer 41, improved topsoil layer 42, biological-zeolite composite filter layer 43, graded crushed stone diversion layer 44, permeable concrete base layer 45, slope base protection strip 50. Detailed Implementation

[0022] To more clearly illustrate the purpose, technical solution, and beneficial effects of this application, a further detailed description of this application is provided below in conjunction with illustrations and specific embodiments. It should be specifically noted that the specific embodiments described below are only for illustrating the technical content of this application and do not constitute a limitation on the scope of protection of this application.

[0023] Regarding the explanation of terminology: In this application, "and / or" is used to describe the relationship between related objects, covering three possible situations: taking "A and / or B" as an example, it can indicate the situation where only A exists, A and B exist simultaneously, or only B exists; the symbol " / " indicates the "or" relationship between related objects, such as "A / B" which refers to A or B.

[0024] Regarding the description of the embodiments: The terms "exemplary" and "for example" appearing in this application are only used to illustrate the technical solutions through specific examples. It should be particularly emphasized that any implementation method or design scheme marked as "exemplary" or "for example" should not be construed as having an advantage over other solutions. Such expressions are only used to present the technical concepts more intuitively.

[0025] Example 1: See Figure 1 This embodiment provides a multi-level collaborative ecological revetment structure suitable for water level fluctuation zones. From the water area to the land area, it includes a gradient riprap protection zone 10, a composite collaborative water level fluctuation zone, a stepped ecological purification zone 40, and a slope base protection belt 50. The slope base protection belt 50 is set along the slope on the land side of the revetment structure. The slope base protection belt 50 includes geogrid and biomineralized improved soil. The geogrid is set along the slope and embedded in the biomineralized improved soil. Urease is mixed in the biomineralized improved soil to produce a bacterial agent, and the slope soil is solidified in situ through microbial mineralization.

[0026] The gradient riprap protection zone 10 lays the foundation for stability and resists underwater erosion; the composite synergistic water level fluctuation zone is used to achieve the triple functions of stability, purification, and ecology; the stepped ecological purification zone 40 is used to intercept land pollution and provide targeted replenishment for synergistic purification; the slope base protection belt 50 is used to strengthen the slope soil in situ and supplement stability. Through slope stabilization, land pollution interception, and intermediate purification, an integrated system of stability, purification, and ecology is formed, which not only solves the pain point of the single function of traditional bank protection, but also achieves dual pollution control on land and in water and the connection of water and land ecological corridors. Furthermore, a slope base protection strip 50 is set on the slope surface. The slope soil is solidified in situ through microbial mineralization. Microbial mineralization solves the problem of insufficient soil strength and easy loss, fundamentally improving the slope soil's resistance to erosion and scouring. The mesh constraint of the geogrid can enhance the integrity of the solidified body, preventing it from cracking and falling off under the impact of water flow. At the same time, it provides additional anti-sliding force. The binding rigidity of biomineralization and the reinforcement flexibility of geogrid complement each other, ensuring the high strength and low permeability of the improved soil. The geogrid also solves the shortcomings of the improved soil in terms of embrittlement and poor crack resistance. At the same time, it is suitable for the engineering scenarios' requirements for bearing capacity, stability and seepage prevention.

[0027] In this embodiment, biomineralized improved soil is installed on the slopes of the gradient riprap protection zone 10, the composite synergistic water level fluctuation zone, and the stepped ecological purification zone 40 on the landward side, as well as on the slope surface near the top of the stepped ecological purification zone 40. The biomineralized improved soil utilizes a urease-producing agent to induce a microbial-induced calcium carbonate deposition reaction. Essentially, it binds soil particles through microbial metabolic activity, transforming loose soil into a rock-like structure. Microbial mineralization tightly binds the soil to the geogrid, preventing the geogrid from detaching from the soil. The geogrid provides a stable mechanical environment for the mineralization reaction, preventing soil particle loss during the reaction process. Ultimately, it forms a slope protection system with a hard internal bond and a strong external constraint. The geogrid can be fixed and supported on the slope using anchor bolts. In this embodiment, the urease-producing agent includes one or more of Bacillus pasteurellii, Bacillus spheroidae, Alcaligenes, Klebsiella pneumoniae, and Pseudomonas.

[0028] Specifically, the gradient riprap protection zone 10 is constructed from bottom to top in layers of riprap with particle sizes of 25-35cm, 35-45cm, and 45-55cm. The spaces between the riprap are filled with permeable polymer mortar with a joint width of 2-3cm. Expansion joints are set every 3-4m, and the expansion joints are filled with a composite structure of asphalt hemp fiber and bentonite waterproofing blanket. The top surface of the riprap is located 60-90cm below the normal water level and is inclined at 10-15° towards the water area. The bottom riprap is embedded in the slope toe soil to a depth of not less than 1.2m.

[0029] The gradient riprap protection zone 10 adopts a design with increasing particle size and sloping surface. The bottom layer of large-diameter riprap is embedded in the soil to enhance the overturning resistance. The upper layer of riprap gradually reduces the particle size and optimizes the gradation. It is filled with permeable polymer mortar to ensure both structural compactness and permeability. The composite filling structure in the expansion joint can effectively absorb temperature stress and water flow impact energy, prevent cracking of the riprap masonry, ensure the long-term stability of the slope toe foundation, and avoid water erosion.

[0030] Specifically, the composite synergistic water level fluctuation zone includes a lower reinforced stabilization layer 20 and an upper composite ecological layer 30. The lower reinforced stabilization layer 20 is a permeable retaining wall constructed by dry stacking hollow ecological fish nest bricks. The interior of the bricks and the back of the wall are filled with a composite filler of gravel, carbon source filler and biological ceramic particles. The carbon source filler is a mixture of sulfur and limestone particles. Three layers of geotextile filter layer are laid on the land side of the retaining wall, and a 6-10cm thick graded sand cushion layer is sandwiched between adjacent geotextile layers.

[0031] The mass ratio of sulfur to limestone in the carbon source filler is 1:3, and the volume ratio of gravel, carbon source filler, and bio-ceramic particles is 3:1:1. The hollow ecological fish nest bricks are made of a composite material of clay, basalt fiber, and polyethylene fiber, with a compressive strength of not less than 30 MPa.

[0032] The lower reinforcement and stabilization layer 20 is embedded in the trapezoidal groove 11 at the top of the gradient riprap protection zone 10. The hollow ecological fish nest brick has a double-layer honeycomb structure. Several nest holes with a diameter of 12-16cm are opened on the front of the brick, and water permeable holes with a diameter of 5-8cm are opened on the back. Bionic protrusions are set on the inner wall of the nest holes.

[0033] The double-layer honeycomb structure of the ecological fish nest bricks is constructed by dry-laying and interlocking, forming a stable wall without mortar. The nest holes on the front provide habitat and spawning space for fish, shrimp, and crabs, while the permeable holes on the back ensure smooth water flow and infiltration. In the composite filler, gravel provides skeletal support and attachment points for microorganisms, while the mixed carbon source filler of sulfur and limestone provides a continuous carbon source for denitrifying bacteria. Bio-ceramic particles enhance adsorption performance. The three work together to form an internal denitrification filter layer, which can actively degrade nitrate nitrogen in the water. The three-layer geotextile filter layer, together with the graded sand cushion layer, effectively prevents soil loss on the land side while ensuring water permeability.

[0034] See Figure 1 The upper composite ecological layer 30 includes ecological bags 31 and connecting buckles 32. The ecological bags 31 are made of a blend of polyester fiber, coconut fiber and basalt fiber. The bags are filled with a mixed matrix of improved vegetative soil, biochar and water-retaining agent with a mixing mass ratio of 8:1:1. The connecting buckles 32 are used to fix the layers and bags together. The bottom ecological bag 31 is connected to the hollow ecological fish nest bricks of the lower reinforcement and stabilization layer 20 through a wedge-shaped interlocking groove to form a fully embedded interlocking connection.

[0035] Furthermore, the upper composite ecological layer consists of a mixed community of 30 flood-tolerant aquatic plants, including reeds, cattails, and loosestrife; the improved vegetation soil is made by mixing garden soil, humus, perlite, vermiculite, and wood ash in a mass ratio of 5:3:1:0.5:0.5, with a pH value of 6.8-7.8 and an organic matter content of not less than 3%.

[0036] The eco-bag's blended material combines high strength, corrosion resistance, and water permeability. In the functional plant substrate, biochar enhances pollutant adsorption, while water-retaining agents improve the plants' drought and flood resistance. Connecting buckles allow for three-dimensional fixation of the eco-bag horizontally, vertically, and diagonally. Combined with wedge-shaped interlocking grooves and fully embedded ecological fish nest bricks, a mechanical interlock is formed to prevent the eco-bag from slipping. The roots of the flood-tolerant aquatic plant mixed community can penetrate the eco-bag, forming a three-dimensional purification network with the lower filler material, while simultaneously providing a habitat for amphibians.

[0037] Specifically, the vertical height ratio between the lower reinforcing and stabilizing layer 20 and the upper composite ecological layer 30 is 1:2-2.5. Multiple transverse intercepting channels are installed on the slope of the upper composite ecological layer 30, filled with a mixture of gravel and expanded clay pebbles, with a spacing of 2.5-3.5m between the channels. These intercepting channels disperse slope water flow, reducing erosion, while simultaneously providing additional water supply to the plants.

[0038] The stepped ecological purification zone 40 includes, from top to bottom, a topsoil layer 41, an improved topsoil layer 42, a bio-zeolite composite filter layer 43, a graded crushed stone diversion layer 44, and a permeable concrete base layer 45. Y-shaped permeable diversion pipes are embedded in the graded crushed stone diversion layer 44, with a spacing of 1.2-1.8m between the permeable diversion pipes. One branch of the permeable diversion pipe at the lower end connects to the upper composite ecological layer 30, and the other branch extends to the lower reinforcement and stabilization layer 20. In the bio-zeolite composite filter layer 43, the volume ratio of biochar to zeolite is 2:1, the particle size is 4-6mm, and the thickness is 10-15cm.

[0039] Furthermore, the surface vegetation layer 41 is planted with a mixed plant community of iris, calamus, canna and black-eyed Susan. A buffer zone with a width of 1.5-2.0m is set around the stepped ecological purification area. The buffer zone is paved with a mixed sod of tall fescue, alfalfa and white clover. The slope of the buffer zone is 1:3.5-1:4.5. The permeable concrete base layer 45 is 15-20cm thick. The stepped ecological purification zone 40 extends the flow path and hydraulic residence time of surface runoff. The surface mixed plant community removes pollutants through root adsorption and absorption, and the improved cultivated soil layer further filters silt and some organic matter. The biochar-zeolite composite filter layer 43 uses adsorption properties to deeply remove heavy metals and phosphorus. The permeable diversion pipe realizes the directional replenishment of purified rainwater. Part of it is introduced into the upper composite ecological layer 30 to supply water for plants, and the other part is introduced into the lower enhanced stabilization layer 20 for secondary purification.

[0040] Example 2: This embodiment also provides a construction method applicable to the revetment structure in Embodiment 1, including the following steps: S1. Conduct on-site surveys and mark the normal water level line and historical highest and lowest water level lines. Trim and compact the slope to the design slope ratio of 1:3-1:4. Use a lightweight dynamic penetrometer to test the bearing capacity of the slope soil to ensure that it is not less than 130 kPa. S2. Excavate the stepped foundation trench of the gradient riprap protection zone 10, remove the loose soil and silt, and build the gradient riprap in layers. Fill the mortar joints with permeable polymer mortar and vibrate to compact them. Set up expansion joints and composite filling structures. S3. Lay a graded crushed stone cushion layer with waterproofing agent above the gradient riprap protection zone 10, dry-lay hollow ecological fish nest bricks, simultaneously fill composite filler in layers and compact it, and lay three layers of geotextile filter layer and sand cushion layer. S4. Lay ecological bags 31 from bottom to top, fix them with connecting buckles 32 and lock them with hollow ecological fish nest bricks, plant flood-resistant aquatic plant mixed community, and water and maintain them. S5. Construct a stepped ecological purification zone of 40, and lay permeable concrete base layer, graded crushed stone diversion layer, biochar-zeolite composite filter layer and improved topsoil in sequence. Install permeable diversion pipes and conduct water flow test, and plant mixed plant community. S6. Embed the geogrid into the slope soil, lay bio-mineralized improved soil on the upper and lower sides of the geogrid to form a slope base protection zone 50, lay planting soil on the top slope, and plant drought-resistant herbaceous plants on the planting soil.

[0041] Example 3: A multi-level collaborative ecological bank protection structure suitable for water level fluctuation zones was applied to a reservoir area with a normal water level fluctuation range of 1.5m. The specific structure is as follows: Gradient riprap protection zone 10: The riprap is constructed in layers from bottom to top using riprap with a particle size of 25-35cm, 35-45cm, and 45-55cm. The spaces between the riprap are filled with permeable polymer mortar with a mortar joint width of 2cm. Expansion joints are set every 3m and filled with asphalt hemp fiber and bentonite waterproofing blanket. The top surface of the riprap is located 60cm below the normal water level and is inclined at 10° towards the water area. The bottom riprap is embedded 1.2m into the soil at the toe of the slope.

[0042] Composite and coordinated water level fluctuation zone: Lower reinforcement and stabilization layer 20: Hollow ecological fish nest bricks are made of composite material of clay, basalt fiber and polyethylene fiber. Four nest holes with a diameter of 12cm are opened on the front and water permeable holes with a diameter of 5cm are opened on the back. They are dry-stacked and interlocked. The interior and the back of the wall are filled with gravel, sulfur / limestone mixed carbon source filler and biological ceramic particles in a volume ratio of 3:1:1. The mass ratio of sulfur to limestone in the carbon source filler is 1:3. Three layers of geotextile filter layer are laid on the land side, with a 6cm graded sand cushion layer in the middle. The upper composite ecological layer 30: The ecological bag 31 is made of a blend of polyester fiber, coconut fiber and basalt fiber. The bag is filled with improved planting soil, biochar and water-retaining agent (mass ratio 8:1:1) and fixed by connecting buckle 32. The bottom ecological bag and ecological fish nest brick are fully embedded and locked. A mixed community of reeds, cattails and loosestrife is planted with a plant ratio of 4:3:2 and a planting density of 20 plants / m².

[0043] The stepped ecological purification zone 40 consists of the following layers from top to bottom: a top vegetation layer (iris, calamus, canna, and black-eyed Susan mixed planting, improved topsoil layer, 20cm thick); a biochar-zeolite composite filter layer (volume ratio 2:1, 10cm thick); a graded gravel drainage layer (particle size 12-20mm, 20cm thick); a permeable concrete base layer (15cm thick); and permeable drainage pipes spaced 1.2m apart within the graded gravel drainage layer, surrounded by a 1.5m wide buffer zone with a mixed planting of tall fescue, alfalfa, and white clover, and a buffer zone slope of 1:3.5.

[0044] A 15cm thick graded crushed stone cushion layer is laid between the gradient riprap protection zone and the composite synergistic water level fluctuation zone, with 4% cement-based penetrating crystalline waterproofing agent added. The vertical height ratio between the lower reinforcing and stabilizing layer and the upper composite ecological layer is 1:2. Four transverse intercepting trenches are set on the slope of the upper composite ecological layer, spaced 2.5m apart, and filled with a mixture of gravel and ceramsite.

[0045] A slope base protection strip 50 is set on one side of the stepped ecological purification zone 40. Urease-producing bacteria, such as Bacillus pasteurellii, mixed in the biomineralized soil, multiply and activate rapidly under soil moisture and nutrient conditions. The urease produced can efficiently decompose urea in the soil. The urease-producing bacteria form a stable bacterial community in the soil. As long as there is moisture and a small amount of nutrients, they can continuously produce urease to trigger mineralization reactions, so that calcium carbonate deposition is continuously replenished, ensuring the long-term stability of the solidified body. The construction was carried out in stages according to the above method. After one year of monitoring after the completion of the construction, the revetment structure showed no slippage or cracking, and its stability met the standards; the removal rate of nitrate nitrogen in the water reached more than 65%, and the removal rate of heavy metals reached more than 80%, with a significant purification effect; the number of fish and birds around the reservoir increased by 40% compared with before the construction, and the ecological corridor function was effectively realized.

[0046] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the invention. Modifications and variations made by those skilled in the art in accordance with the spirit of the invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A multi-stage synergistic ecological revetment structure suitable for water level fluctuation area, characterized in that: From the water area to the land area direction includes gradient riprapping protection area (10), composite synergistic water level change area, stepped ecological purification area (40) and slope base protection belt (50) in turn, the slope base protection belt (50) is arranged along the slope of the land area side of revetment structure, and the slope base protection belt (50) includes geogrid and biomineralization improved soil, the geogrid is arranged along the slope, the geogrid is embedded and laid in the biomineralization improved soil along the slope, the biomineralization improved soil is mixed with urease producing bacteria agent, and the slope soil in situ solidification is realized through the microbial mineralization.

2. The multi-stage synergic ecological revetment structure suitable for water level fluctuation area according to claim 1, characterized in that: The gradient riprapping protection area (10) is layered and built from bottom to top by block stone with particle size of 25-35 cm, 35-45 cm and 45-55 cm, the block stone is filled with water permeable polymer mortar between, the mortar joint width is 2-3 cm, expansion joint is set every 3-4 m, the expansion joint is filled with the composite structure of asphalt flock and bentonite waterproof blanket, and the embedded depth of the bottom block stone in the slope toe soil body is not less than 1.2 m.

3. The multi-stage synergic ecological revetment structure suitable for water level fluctuation area according to claim 1, characterized in that, The composite synergistic water level change area includes lower reinforced stable layer (20) and upper composite ecological layer (30), the lower reinforced stable layer (20) is a permeable retaining wall built by hollow ecological fish nest bricks, the inside of the brick body and the back of the wall are filled with composite fillers of gravel, carbon source filler and biological ceramsite, the carbon source filler is mixed with sulfur and limestone particles, three layers of geotextile filter layers are laid on the land side of the retaining wall, and 6-10 cm thick graded sand cushion layers are arranged between adjacent two layers of geotextile.

4. The multi-stage synergic ecological revetment structure suitable for water level fluctuation area according to claim 3, characterized in that, The lower reinforced stable layer (20) is embedded and installed in the trapezoidal groove (11) on the top of the gradient riprapping protection area (10), the hollow ecological fish nest brick has a double-layer honeycomb structure, a plurality of nest hole with diameter of 12-16 cm are formed on the front of the brick body, a plurality of water permeable holes with diameter of 5-8 cm are formed on the back of the brick body, and bionic protrusions are arranged on the inner wall of the nest hole.

5. The multi-stage synergic ecological revetment structure suitable for water level fluctuation area according to claim 3, characterized in that, The upper composite ecological layer (30) includes ecological bag (31) and connecting buckle (32), the ecological bag (31) is made of polyester fiber, coconut shell fiber and basalt fiber blended material, the bag is filled with mixed substrate of improved plant soil, biochar and water retaining agent, the mass ratio of the mixed substrate is 8:1:1, the adjacent ecological bags (31) are fixed through the connecting buckle (32), and the bottommost ecological bag (31) is connected with the hollow ecological fish nest brick of the lower reinforced stable layer (20) through wedge-shaped embedded groove to form full-embedded interlocking connection.

6. The multi-stage synergic ecological revetment structure suitable for water level fluctuation area according to claim 5, characterized in that, The upper composite ecological layer (30) is planted with flood-tolerant aquatic plant mixed communities, the mixed communities include reed, cattail and alternanthera philoxeroides, the improved plant soil is made of garden soil, humus soil, perlite, vermiculite and wood ash at a mass ratio of 5:3:1:0.5:0.5, the pH value is 6.8-7.8, and the organic matter content is not less than 3%.

7. The multi-stage synergic ecological revetment structure suitable for water level fluctuation area according to claim 3, characterized in that, The vertical height ratio of the lower reinforced stable layer (20) to the upper composite ecological layer (30) is 1:2-2.5, and a plurality of transverse water interception grooves are arranged on the slope surface of the upper composite ecological layer (30), the water interception grooves are filled with a mixture of gravel and ceramsite, and the spacing between the water interception grooves is 2.5-3.5 m. 8.The multi-stage synergic ecological revetment structure suitable for water level fluctuation area according to claim 1, characterized in that, The stepped ecological purification area (40) comprises, from top to bottom, a surface vegetation layer (41), a modified cultivated soil layer (42), a biological-boiling stone composite filter layer (43), a graded broken stone flow guide layer (44), and a water permeable concrete base layer (45). The graded broken stone flow guide layer (44) is embedded with Y-shaped water permeable flow guide pipes, the distance between the water permeable flow guide pipes is 1.2-1.8 m, one branch of the lower end of the water permeable flow guide pipes is connected to the upper composite ecological layer (30), and the other branch extends to the lower enhanced stability layer (20). The volume ratio of the biological charcoal to the boiling stone in the biological-boiling stone composite filter layer (43) is 2:1, the particle diameter of the biological charcoal and the boiling stone is 4-6 mm, and the thickness is 10-15 cm. 9.The multi-stage synergic ecological revetment structure suitable for water level fluctuation area according to claim 8, characterized in that, The surface vegetation layer (41) is planted with mixed plant communities of irises, aconites, canes, and black heart chrysanthemums. A buffer zone with a width of 1.5-2.0 m is arranged around the stepped ecological purification area. The buffer zone is paved with mixed sod of tall fescue, alfalfa, and white clover. The slope of the buffer zone is 1:3.5-1:4.

5. The thickness of the water permeable concrete base layer (45) is 15-20 cm.

10. A method of construction of a revetment structure as claimed in any one of claims 1 to 9, characterised in that, The method comprises the following steps: S1, on-site survey and calibration of the constant water level line, the highest and lowest water level line, and trimming of the compacted slope surface to a design slope ratio of 1:3-1:4, and detection of the slope soil bearing capacity by using a light dynamic sounding instrument; S2, excavation of the stepped base trench of the gradient riprap protection area (10), layered masonry of the gradient riprap after removal of floating soil and sludge, filling of the mortar joints with water permeable polymer mortar and vibration and compaction, setting of expansion joints and composite filling structure; S3, laying of a graded broken stone cushion layer mixed with a waterproof agent on the gradient riprap protection area (10), dry masonry of hollow ecological fish nest bricks, simultaneous layered filling of composite filler and ramming, laying of three layers of geotextile filter layers and sand cushion layers; S4, laying of ecological bags (31) from bottom to top, fixing by connecting buckles (32) and embedding and locking connection with the hollow ecological fish nest bricks, implantation of flood-tolerant aquatic plant mixed communities, watering and curing; S5, construction of the stepped ecological purification area (40), laying of a water permeable concrete base layer, a graded broken stone flow guide layer, a biological charcoal-boiling stone composite filter layer, and modified cultivated soil in sequence, installation of water permeable flow guide pipes and water test, and planting of mixed plant communities; S6, embedding of a geogrid into the slope soil, laying of biological mineralized modified soil on the upper and lower sides of the geogrid to form a slope base protection belt (50), laying of planting soil on the top slope, and planting of drought-resistant herbaceous plants on the planting soil.

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