Bridge foundation anti-scouring reinforcing system and method based on plant fiber network

Abstract

The invention provides a bridge foundation anti-scouring reinforcing system and method based on a plant fiber network, the system comprises a plant fiber network unit and a foundation protection structure, and the plant fiber network unit comprises a fiber mesh pad covering the periphery of a bridge foundation and a planting matrix covering the fiber mesh pad; the fiber mesh pad is located above the bottom-layer protection pad, a honeycomb-shaped or staggered grid-shaped three-dimensional grid is arranged in the fiber mesh pad, and the foundation protection structure comprises a flow guide plate arranged in the upstream area of the bridge foundation and the bottom-layer protection pad covering the bottom of the bridge foundation. The invention further provides a reinforcing method of the system. Through the synergistic effect of the plant root system and the fiber mesh pad, the soil body is reinforced, scouring is reduced, the anti-scouring capacity of the bridge foundation is remarkably improved, the water flow impact strength is reduced through the foundation protection structure, soil body emptying is prevented, ecological protection, construction economy and engineering applicability are achieved, and the construction cost is reduced. The method is suitable for anti-scouring reinforcement scenes of bridge foundations in water areas such as rivers and lakes.

Description

Technical Field

[0001] The present invention belongs to the technical field of bridge foundation reinforcement and ecological protection in civil engineering, and particularly relates to a bridge foundation anti-scouring reinforcement system and method based on a plant fiber network. Background Art

[0002] Bridge foundations operate in water flow environments such as rivers and lakes for a long time, and their safety and stability are easily affected by scouring. Especially in extreme environments such as heavy rain, floods, and strong water flows, soil erosion around the foundation will form scouring pits, leading to bridge foundation settlement, inclination, and even overall structural instability, seriously threatening traffic safety and the normal operation of infrastructure. To address the scouring problem, various anti-scouring reinforcement technologies have been developed in engineering practice, mainly including rigid armor technology, flexible armor technology, and vegetation ecological slope protection technology, etc.

[0003] (1) Rigid Armor Technology

[0004] Rigid armor technology usually uses materials such as concrete armor, gabions, and steel sheet piles to directly resist the impact of water flow scouring on the bridge foundation by constructing a solid outer protection structure. This type of technology can provide a high anti-scouring ability, but there are the following defects in practical applications:

[0005] Poor adaptability: Rigid armor cannot adapt to complex hydrodynamic environments, and it is easy to form vortices locally or accelerate water flow scouring, causing secondary damage to the surrounding riverbed or bank slope.

[0006] Environmental impact: Large-scale use of hard materials such as concrete or steel will damage the surrounding ecological environment, change the natural flow state of water bodies, and affect the habitats of aquatic animals and plants.

[0007] Cost and maintenance: The construction and maintenance costs of rigid armor are relatively high. Especially after extreme events such as floods, the repair costs of damaged armor are huge.

[0008] (2) Flexible Armor Technology

[0009] Flexible armor technology absorbs part of the water flow impact and reduces the scouring effect by laying flexible materials such as geotextiles, reinforced meshes, and flexible geogrids to fit the terrain of the bridge foundation. Compared with rigid armor, flexible armor has certain adaptability and economy, but there are still the following deficiencies:

[0010] Insufficient durability: Flexible materials are easily torn or displaced in strong water flow or long-term scouring environments, and it is difficult to provide long-term and reliable anti-scouring effects.

[0011] Material pollution: Many flexible armor materials are non-degradable plastic or synthetic fiber materials, and long-term use will cause pollution to water and soil environments.

[0012] Local scour problem: Flexible armor may change the water flow path, leading to increased local scour in the uncovered area, further damaging the stability of the bridge foundation.

[0013] (3) Vegetation ecological slope protection technology

[0014] Vegetation ecological slope protection technology reduces soil erosion by planting plants around riverbanks or bridge foundations and utilizing the soil-fixing effect of plant roots and the protection ability of the covering layer. This type of technology has certain advantages in ecological restoration and soil and water conservation, but its limitations are also very obvious:

[0015] Limited scour resistance: Plant roots are difficult to maintain stability under strong water flow conditions. Especially in floods or high hydrodynamic environments, plants may be uprooted and lose their protective effect.

[0016] Long growth cycle: The formation of the soil-fixing ability of plants depends on the growth process of the roots, which is difficult to meet the need for rapid reinforcement. Especially in the case of sudden water flow scour, it cannot provide immediate protection.

[0017] Insufficient synergy: The combination of vegetation technology and other reinforcement means is less, making it difficult to achieve comprehensive protection. Especially under extreme conditions, it is easy to lead to the failure of protection.

[0018] (4) Existing technologies for the combination of flexible armor and vegetation

[0019] In recent years, the combination of flexible armor and vegetation technology has gradually received attention. For example, by laying planting substrates on flexible armor and planting plants, the initial scour resistance of flexible armor and the long-term soil-fixing function of plant roots are utilized. However, this technology still has the following defects in practical applications:

[0020] Poor system synergy effect: There is a lack of effective synergy between flexible armor and plant roots, unable to fully exert the comprehensive advantages of the two, and the bonding force between the roots and the armor is poor.

[0021] Insufficient scour resistance performance: Flexible armor is easily damaged under strong water flow, and the protective effect of plant roots takes a long time to appear, with limited protection effect in extreme environments.

[0022] Poor ecological compatibility: Many flexible armor materials are non-degradable, posing a potential threat to the water body ecological environment. At the same time, the selection of plant species is not optimized for the local environment, resulting in poor ecological adaptability.

[0023] In summary, the existing scour resistance reinforcement technologies generally have the following problems:

[0024] Lack of comprehensiveness: Single rigid armor, flexible armor or vegetation technology cannot comprehensively cope with complex scour environments, and the effect of collaborative protection is limited.

[0025] Ecological damage: Many technical solutions have negative impacts on the surrounding ecological environment, such as changing the flow pattern of water, polluting soil and water bodies.

[0026] Poor adaptability: It is difficult to simultaneously meet the stability requirements of engineering structures and the sustainable development needs of the environment, and it is prone to failure especially under extreme hydrodynamic conditions. Summary of the Invention

[0027] In view of the problems existing in the above-mentioned prior art, the present invention proposes a bridge foundation anti-scour reinforcement system and method based on a plant fiber network. The purpose is to form a multi-level collaborative protection system by combining the ecological soil fixation function of plant roots and the physical reinforcement effect of the fiber mesh mat, improve the anti-scour ability of the bridge foundation, take into account engineering stability and ecological environment protection, and solve the problems of insufficient anti-scour performance, environmental damage and complex construction in the prior art.

[0028] To achieve the above object, the specific scheme of the present invention is as follows:

[0029] A bridge foundation anti-scour reinforcement system based on a plant fiber network includes a plant fiber network unit and a foundation protection structure. The plant fiber network unit includes a fiber mesh mat covering the periphery of the bridge foundation and a planting substrate covering the fiber mesh mat. The fiber mesh mat is provided with a three-dimensional grid in a honeycomb shape or an intersecting grid shape. The foundation protection structure includes a guide plate arranged in the upstream area of the bridge foundation and a bottom layer cushion covering the bottom of the bridge foundation, and the fiber mesh mat is located above the bottom layer cushion.

[0030] Furthermore, it further includes a monitoring unit. The monitoring unit includes an unmanned aerial vehicle (UAV) inspection device and an embedded sensor installed in the fiber mesh mat. The UAV inspection device is used to regularly monitor plant growth, scour pit formation, the integrity of the foundation protection structure and soil stability. The flight height of the UAV inspection device is 50 - 100m, and the image resolution of the UAV inspection device is not less than 1080p; the embedded sensor includes a soil displacement sensor, a water flow velocity sensor and a plant root monitoring sensor.

[0031] Furthermore, the fiber mesh mat is made of a biodegradable natural fiber material or a high-strength synthetic fiber. The biodegradable material includes coconut shell fiber or hemp fiber, and the high-strength synthetic fiber includes polylactic acid fiber. The mesh hole diameter of the fiber mesh mat is 5 - 20mm, the tensile strength ≥ 20MPa, the water permeability ≥ 90%. The planting substrate is composed of river sand, humus soil and organic fertilizer. The particle diameter of the river sand is 0.1 - 2mm, the humus soil contains organic matter ≥ 10%, 3kg of nitrogen, phosphorus and potassium fertilizers are added per cubic meter of the planting substrate, the thickness of the planting substrate is 50 - 100mm, and the height of the three-dimensional grid is 10 - 20mm.

[0032] Further, the flow deflector is a semi-permeable flow deflector made of corrosion-resistant polymer material. The corrosion-resistant polymer material is high molecular polyethylene or composite material. The porosity of the flow deflector is 20% - 40%, and it forms an angle of 30° - 45° with the water flow direction. The depth of the bottom of the flow deflector buried in the soil is 20 - 30 cm, and it is fixed by anchor piles.

[0033] Further, the bottom cushion is made of high-strength fiber material, with a thickness of 30 - 50 mm and a water permeability of ≥90%. The high-strength fiber material is polyester fiber or fiberglass reinforced material.

[0034] The method for anti-scour reinforcement of bridge foundation using the reinforcement system includes the following steps:

[0035] Step 1, scour risk assessment: Divide the scour risk levels of the bridge foundation. The scour risk levels include high-risk areas, medium-risk areas, and low-risk areas. Output a risk assessment report and generate a scour intensity distribution map of the bridge foundation;

[0036] Step 2, fiber mesh mat laying: According to the scour intensity distribution map of the bridge foundation in Step 1, choose to lay the fiber mesh mat in high-risk areas. The coverage area of the fiber mesh mat exceeds 50% of the width of the bridge foundation, and fix the edges of the fiber mesh mat with anchor nails or steel piles. The spacing of the anchor nails or steel piles does not exceed 1 m, and the penetration depth into the soil is not less than 50 cm;

[0037] Step 3, plant planting: Fill the planting substrate on the fiber mesh mat in Step 2 and sow plant seeds;

[0038] Step 4, flow deflector arrangement: Arrange a flow deflector with a porosity of 20% - 40% in the upstream area of the bridge foundation. The flow deflector forms an angle of 30° - 45° with the water flow direction and is fixed by anchor piles;

[0039] Step 5, data monitoring: Install embedded sensors in the fiber mesh mat, and real-time monitor the soil stability and plant growth conditions through the embedded sensors and the drone inspection device.

[0040] Further, the scour risk assessment in Step 1 includes the following steps:

[0041] Step 11, collect the topographic data, hydrological data, riverbed material parameters, and bridge structure parameters of the bridge foundation;

[0042] Step 12, construct a hydrological model based on the data collected in Step 11 and conduct simulation calculations to obtain simulation results;

[0043] Step 13, divide the scour risk levels of the bridge foundation according to the simulation results in Step 12.

[0044] Furthermore, the scouring depth of the high-risk area is greater than 20 cm, and the water flow velocity is greater than 4 m / s; the scouring depth of the medium-risk area is 10 - 20 cm, and the water flow velocity is 2 - 4 m / s; the scouring depth of the low-risk area is less than 10 cm, and the water flow velocity is lower than 2 m / s.

[0045] Furthermore, in step 3, the thickness of the planting substrate is 50 - 100 mm, and 200 - 300 plant seeds are sown per square meter. The plant seeds include the seeds of cattail, reed or hygrophila.

[0046] Furthermore, in step 5, the inspection frequency of the UAV inspection device is once a month, and replanting is required when the plant coverage rate is less than 50%.

[0047] Advantages of the present invention

[0048] 1. The anti-scouring reinforcement system and method for bridge foundation based on plant fiber network of the present invention constructs a multi-level reinforcement system through the synergistic effect of plant fiber network units and plant roots, realizing efficient anti-scouring protection in a strong water flow environment. The physical reinforcement effect of the fiber mesh pad enhances the soil stability and provides a firm attachment foundation for plant roots. The semi-permeable flow guiding plate made of corrosion-resistant polymer material effectively disperses the water flow impact force, reduces the scouring effect in local areas, and further enhances the overall protection effect of the system. Compared with the prior art, the present invention can still maintain the stability of the bridge foundation in an extreme hydrodynamic environment.

[0049] 2. The present invention uses biodegradable natural fiber materials such as coconut shell fiber and hemp fiber or high-strength synthetic fiber to make fiber mesh pads, and plants cattail, reed, hygrophila plants adapted to the local ecological environment, combining ecological protection and engineering reinforcement functions. The biodegradable natural fiber materials avoid the pollution problems of non-degradable synthetic materials in traditional flexible armors to water bodies and soils. The adaptability of local plant species improves the survival rate and recovery speed of vegetation. The combined action of plant roots, stems and leaves coverage and fiber mesh pads improves the water and soil environment around the bridge foundation and provides good habitat conditions. Compared with traditional rigid or flexible armor technologies, the present invention significantly reduces the damage to the surrounding ecological environment and contributes to the long-term restoration and sustainable development of the ecological environment.

[0050] 3. Through the multi-functional design of the fiber mesh mat and the continuous growth of plant roots, the present invention forms a dynamically stable anti-scour reinforcement system, which can adapt to different hydrodynamic conditions and complex terrains. The combination of the growth of plant roots and the mesh mat enables the reinforcement effect of the system to gradually enhance over time, maintaining stability even during the flood season or in high-flow environments. The flexible structure of the fiber mesh mat can conform to the complex geometry of the bridge foundation, filling the blind spots that cannot be effectively covered by existing rigid armors. The plant fiber network gradually strengthens as the plant roots penetrate deeper, overcoming the problems of easy aging or failure of existing flexible armors.

[0051] 4. Compared with the high cost and complex construction process of traditional rigid armors, the present invention has the advantages of simple construction, low cost, and convenient maintenance. The fiber mesh mat is a prefabricated structure that can be quickly laid around the bridge foundation, significantly shortening the construction time. Planting and laying of the mesh mat are completed simultaneously without additional complex processes. The maintenance cost is low, and the operation status of the system can be evaluated through conventional monitoring equipment (such as sensors, drones). The growth of plant roots and the degradation process of fiber materials are completed naturally without frequent repairs.

[0052] 5. The present invention integrates the functions of anti-scour, soil fixation, and environmental protection, achieving the goal of comprehensive protection of bridge foundations. The scour protection function effectively inhibits the loss of foundation soil through the synergistic action of physics and biology, preventing the formation of scour pits. The hydrodynamic energy dissipation device reduces the water flow velocity and impact force, providing a stable growth environment for plants and plant fiber network units. The environmental restoration function restores the ecological environment around the bridge by planting local aquatic plants, bringing the project into harmony with the natural environment.

[0053] 6. The present invention innovatively proposes a reinforcement scheme that combines the ecological function of plant roots with the engineering function of the fiber mesh mat. The structure of the fiber mesh mat strengthens the adhesion of plant roots and enhances the interaction between the soil and plants. The multi-level protection design combines physical and biological functions and is applicable to various hydrodynamic conditions and bridge foundation types. The present invention is applicable to the anti-scour reinforcement requirements of bridge foundations in various water areas such as rivers, lakes, and wetlands, and has good prospects for popularization and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 is a schematic diagram of the overall structure of the anti-scour reinforcement system for bridge foundations of the present invention.

[0055] Figure 2 is Figure 1 a schematic diagram of the foundation protection structure in

[0056] Figure 3 is Figure 1 a schematic diagram of the plant fiber network unit in

[0057] In the figure:

[0058] 1. Bridge foundation; 2. Plant fiber network unit; 21. Fiber mesh pad; 22. Planting substrate; 3. Flow deflector; 4. Bottom cushion; 5. Riverbed. Specific implementation mode

[0059] The present invention will be further explained below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the present specific embodiment is not used to limit the scope of the rights of the present invention.

[0060] As Figures 1 to 3 shown, a bridge foundation 1 anti-scouring reinforcement system based on a plant fiber network provided by the present specific embodiment includes a plant fiber network unit 2, a foundation protection structure, and a monitoring unit.

[0061] The plant fiber network unit 2 includes a fiber mesh pad 21 covering the periphery of the bridge foundation 1 and a planting substrate 22 covering the fiber mesh pad 21.

[0062] The fiber mesh mat 21 is a gasket made of biodegradable natural fiber materials or high-strength synthetic fibers, with good structural toughness and tensile strength, and can remain stable in the water flow scouring environment. The grid structure design of the fiber mesh mat 21 can effectively reduce the direct impact force of the water flow, make the water flow evenly distributed, and thus reduce the erosion force of the water flow on the soil surface. The function of the fiber mesh mat 21 is to provide a stable support structure to enhance soil fixation and support plant growth at the same time. When the mesh diameter of the fiber mesh mat 21 is set to 5 mm to 20 mm and the height of the three-dimensional grid is set to 10 mm to 20 mm, it can adapt to the growth needs of different plant roots, has a significant impact on the annual anti-scouring performance, and smaller mesh sizes and higher grid designs can better limit soil loss and improve the anti-scouring effect. The tensile strength of the fiber mesh mat 21 is ≥20 MPa, and the water permeability is ≥90%, which not only ensures the passage of water flow and avoids water pressure accumulation, but also can enhance the adhesion of plant roots and maintain the stability of the soil mass. The fiber mesh mat 21 is provided with a three-dimensional grid in a honeycomb shape or an interlaced grid shape, and the three-dimensional grid is used to support the fibers and enhance the mechanical properties and stability of the mesh mat. The three-dimensional grid has a high-strength soil consolidation function and plant root adhesion. The height of the three-dimensional grid is 10 to 20 mm to enhance the plant root adhesion ability, improve the wrapping property of the fiber mesh mat 21 to the soil mass, and prevent soil loss. The planting substrate 22 is composed of river sand, humus soil and organic fertilizer. The particle diameter of the river sand is 0.1 to 2 mm to provide good air permeability; the humus soil contains ≥10% organic matter to enhance plant nutrient supply; 3 kg of nitrogen, phosphorus and potassium fertilizers are added to each cubic meter of the planting substrate 22 to promote the rapid growth of plants. The thickness of the planting substrate 22 is 50 to 100 mm, which can not only meet the growth needs of plants, but also avoid excessive thickness causing scouring and accumulation. The planting substrate 22 is used to plant plants with strong anti-scouring ability. The plants include local aquatic plants such as cattail, reed, and Hygrophila salicifolia, which can grow normally within the water depth range of 0 to 50 cm. Specifically as follows:

[0063] I. Materials of the fiber mesh mat 21

[0064] To ensure that the fiber mesh mat 21 has good ecological functions and mechanical properties, two main types of materials are selected in this embodiment: the biodegradable material is coconut coir fiber or hemp fiber, and the high-strength synthetic fiber is polylactic acid fiber. Through reasonable proportioning of these two materials, they can play a synergistic role in ensuring soil consolidation, plant growth, and the durability of the mesh mat.

[0065] (1) Biodegradable materials:

[0066] Coconut coir fiber: As a biodegradable natural fiber, coconut coir fiber has good corrosion resistance and high mechanical strength. It can effectively enhance the ecological friendliness of the mesh mat and naturally degrade in the soil, which is beneficial to environmental restoration.

[0067] Hemp fiber: Hemp fiber is a natural fiber with high tensile strength and corrosion resistance. The naturalness and biodegradability of hemp fiber help improve the soil structure and promote plant root growth in the fiber mesh mat 21.

[0068] (2) High-strength synthetic fiber:

[0069] Polylactic acid fiber (PLA): As a high-strength bio-based synthetic fiber, polylactic acid fiber has high tensile strength, corrosion resistance, and water permeability, and its production process is relatively environmentally friendly. Polylactic acid fiber has good mechanical properties and can improve the stability and durability of the mesh mat.

[0070] II. Material ratio of the fiber mesh mat 21

[0071] To improve the mechanical properties of the fiber mesh mat 21 while ensuring its good ecological function, as shown in Table 1, this embodiment proposes the following several typical material ratio schemes, covering the requirements of different application scenarios.

[0072] Table 1

[0073]

[0074] The above ratio schemes optimize the comprehensive performance of the fiber mesh mat 21 through the combination of different fibers. Different ratio schemes can adjust the biodegradability, strength, durability, and other characteristics of the mesh mat according to actual needs.

[0075] III. Preparation process of the material of the fiber mesh mat 21

[0076] Based on the material selection and ratio, the preparation process is crucial for the performance of the fiber mesh mat 21. This embodiment adopts the following preparation process to ensure the quality and stability of the fiber mesh mat 21.

[0077] (1) Fiber pretreatment:

[0078] Clean and degum the coconut shell fiber and hemp fiber to remove surface impurities and natural gums of the fiber, ensuring the uniformity and adsorption of the fiber.

[0079] Perform heat treatment on the polylactic acid fiber to enhance the crystallinity and heat resistance of the fiber and improve the tensile strength of the fiber.

[0080] (2) Fiber mixing:

[0081] Dry-mix different types of fibers according to the predetermined ratio to ensure uniform distribution of each fiber and avoid excessive aggregation or separation.

[0082] (3) Fiber weaving or hot pressing:

[0083] The mixed fibers are woven or pressed into a mesh pad structure with a certain density and thickness by hot pressing or non-woven process. Through the hot pressing process, a strong bonding force can be formed between the fibers, thereby improving the mechanical properties of the mesh pad.

[0084] The grid structure can be adjusted into various forms such as honeycomb shape, staggered grid shape, etc. according to different requirements to ensure its effects in aspects such as soil consolidation and plant root attachment.

[0085] (4) Mesh pad curing and quality control:

[0086] The formed fiber mesh pad 21 needs to be cured to ensure its stability in different environments. The temperature and time of the curing treatment will be adjusted according to the characteristics of the selected fibers.

[0087] During the whole production process, strict quality inspections are carried out, including indicators such as the tensile strength, water permeability, and corrosion resistance of the mesh pad, to ensure that the quality of each batch of products meets the requirements.

[0088] IV. Analysis of the influence of different material combinations on the performance of the mesh pad

[0089] The different material combinations in this embodiment have a significant impact on the performance of the fiber mesh pad 21. The following is a comparative analysis of each material combination in the main performance indicators.

[0090] (1) Tensile strength:

[0091] Polylactic acid fiber (PLA) has a relatively high tensile strength and can effectively improve the tensile performance of the mesh pad. As the proportion of polylactic acid fiber increases, the tensile strength of the mesh pad increases significantly.

[0092] The fiber mesh pad 21 prepared by the formulation scheme 3 performs relatively excellently in terms of tensile strength and is suitable for areas with strong water flow or loose soil.

[0093] (2) Water permeability:

[0094] Coconut coir fiber and hemp fiber, as natural fibers, have relatively high water permeability and can effectively ensure that water flow is not blocked when passing through the mesh pad, thereby avoiding the adverse effects of water accumulation on plant growth.

[0095] Although polylactic acid fiber is relatively tough, its water permeability is relatively poor. Therefore, a reasonable ratio needs to be adopted to ensure the balance between water permeability and mechanical properties.

[0096] The fiber mesh pad 21 prepared by the formulation scheme 1 has good water permeability and mechanical properties.

[0097] (3) Corrosion resistance:

[0098] Polylactic acid fibers exhibit good corrosion resistance, especially in humid or waterlogged environments, and can maintain a long service life.

[0099] Although coconut shell fibers or hemp fibers are environmentally friendly, they may degrade under long-term water flow scouring or immersion conditions. Therefore, their proportion needs to be adjusted according to different application environments.

[0100] The fiber mesh mat 21 prepared by formulation scheme 4 is suitable for environments with relatively harsh water conditions and can provide strong corrosion resistance and long-term usability.

[0101] Through the above reasonable material ratio and preparation process, the fiber mesh mat 21 of this embodiment has excellent mechanical properties, water permeability, corrosion resistance and other characteristics, and can effectively improve soil stability and promote plant growth in different environments. The material selection and ratio can be adjusted according to specific application requirements to achieve the best effect.

[0102] V. Comparative analysis of the influence experiments of water flow velocity and scouring velocity, as shown in Table 4:

[0103] Table 4

[0104]

[0105] V. Influence of grid shape on the adhesion of plant roots and the consolidation effect of soil mass

[0106] 1. Optimization design of grid shape:

[0107] In order to optimize the growth of plant roots and the consolidation effect of soil, this embodiment proposes two different grid shape designs: honeycomb-shaped and staggered grid-shaped. The design of the grid shape not only affects the mechanical properties of the mesh mat itself, but also has an important impact on the adhesion and growth of plant roots.

[0108] Honeycomb-shaped grid: This grid structure can evenly distribute stress, increase the stability of the soil mass, and provide more attachment points for plant roots, thereby promoting root growth and soil consolidation effect. The honeycomb shape helps to reduce soil erosion by water flow, reduce the scouring depth, and enhance the compressive strength of the soil.

[0109] Staggered grid-shaped grid: The staggered grid design can effectively improve the dispersion of water flow, better distribute the shear force generated when water flows through, and help slow down soil erosion by water flow. In addition, the staggered structure also provides a larger support area for plant roots, promotes the longitudinal growth of roots, and further enhances the stability of the soil mass.

[0110] According to engineering experience, compared with honeycomb grids, staggered grid-like grids can usually provide better support for plant growth and soil consolidation performance under certain conditions, especially in environments with strong water flow.

[0111] 2. Influence of mesh diameter on the adhesion of plant roots and the effect of soil consolidation

[0112] This embodiment proposes three design options for common mesh diameters, namely 5mm, 10mm, and 20mm. The diameter of the mesh has a direct impact on the adhesion of plant roots, soil loss, and the ability of water flow to pass through.

[0113] 5mm mesh: The smaller mesh can effectively prevent soil particle loss and provide more grid support, making it easier for plant roots to adhere, thereby enhancing the stability of plant growth and the effect of soil consolidation.

[0114] 10mm mesh: The moderate mesh size takes into account both water permeability and soil consolidation effect. It is the most commonly used design scheme and can achieve good plant growth and soil stability effects in various environments.

[0115] 20mm mesh: The larger mesh can improve the water permeability, but may cause some soil particle loss. Therefore, it is suitable for areas with strong water flow and serious soil loss. In this case, the larger mesh helps to reduce the scouring force of water flow on the soil.

[0116] According to research, grids with smaller mesh diameters (such as 5mm) can usually provide stronger adhesion of plant roots and enhance the tensile strength of the soil. In contrast, larger meshes (such as 20mm) improve water permeability but provide weaker support for soil stability. Therefore, a moderate mesh size (such as 10mm) can achieve a better balance between ensuring plant growth and soil stability.

[0117] 3. Optimization effect of grid height on plant root growth and soil wrapping

[0118] The height of the grid affects the support ability of the mesh mat and the growth space of plant roots. To optimize root growth and soil wrapping, this invention proposes two designs with different grid heights of 10mm and 20mm.

[0119] 10mm grid height: Suitable for the growth of medium-height plants, it can provide sufficient root attachment points and effectively fix the soil. It is suitable for applications in various environments and can balance plant growth and soil stability.

[0120] 20mm grid height: Suitable for deep-rooted plants or plants that require a large growth space, it provides a larger support space to promote the deep growth of roots, and at the same time can enhance the soil stability and anti-scouring performance.

[0121] Research shows that appropriately increasing the grid height helps provide a larger root growth space, especially having a significant growth promotion effect on deep-rooted plants (such as reeds, cattails, etc.). In addition, the higher grid can further enhance the wrapping property of the soil mass and prevent water flow erosion from carrying away soil particles.

[0122] 4. Comprehensive performance analysis and expected effects

[0123] To sum up, the design of the grid shape, mesh diameter, and grid height in the fiber mesh mat 21 of this embodiment can enhance the soil stability while improving plant growth. As shown in Table 2, the following are the expected effects under different configurations:

[0124] Table 2

[0125]

[0126] By reasonably selecting the grid shape, mesh diameter, and grid height, this embodiment can adapt to different environmental conditions, ensure soil stability, and promote the healthy growth of plants.

[0127] VI. Growth performance of different plant species in the fiber mesh mat 21 and traditional vegetation slope protection

[0128] (1) Cattail is a plant commonly used in wetland restoration, and its root growth usually requires a relatively soft and well-drained soil environment. In traditional vegetation slope protection, the roots of cattail are restricted by the soil structure and grow slowly. However, in the fiber mesh mat 21, due to its good water permeability and soil consolidation property, the roots of cattail can quickly penetrate the mesh mat and fix the soil, thus significantly increasing its growth rate and root adhesion. Research shows that the coverage rate of cattail in the fiber mesh mat 21 will increase by 20% - 30%.

[0129] (2) Reed is a water-tolerant plant widely used in soil and water conservation and ecological restoration. Research shows that the growth rate of reed is relatively slow in traditional slope protection, and the root fixation effect is limited. In contrast, the vegetation slope protection using the fiber mesh mat 21 can provide better root support and enhance its growth potential in a humid environment. Research shows that the growth rate of reed in the fiber mesh mat 21 increases by about 15% - 25%, the root adhesion is enhanced, and the coverage rate also increases significantly.

[0130] (3) Hygrophila salicifolia has strong growth ability in wetland environments, and its roots can help plants fix the soil and prevent water erosion. In traditional vegetation slope protection, the root growth of Hygrophila salicifolia is restricted by soil stability. However, in the fiber mesh mat 21, the roots of Hygrophila salicifolia can grow in a more stable soil structure, significantly improving its growth rate and the adhesion of its roots. Research shows that the root growth rate of Hygrophila salicifolia in the fiber mesh mat 21 increases by 20% - 35%, and the coverage rate will also increase significantly.

[0131] VII. Durability Test

[0132] (1) Tensile Strength and Durability

[0133] Polylactic acid fiber (PLA) is a high-strength material commonly used in the fields of environmental protection and civil engineering, with good tensile strength and durability. Under the conditions of water erosion and long-term immersion, the tensile strength of polylactic acid fiber remains stable, and the degradation rate is slow. Usually, the tensile strength only decreases by about 15% - 20% within 12 months.

[0134] As a biodegradable material, coir fiber shows a relatively high degradation rate during the biodegradation process. However, its tensile strength is relatively stable in the short term and can maintain good supporting ability for a certain period of time. Research shows that the tensile strength of coir fiber decreases by about 20% - 30% within 6 to 12 months under water immersion conditions.

[0135] (2) Permeability Rate and Durability

[0136] Polylactic acid fiber shows good water permeability under the condition of water erosion. According to relevant research, the change in the permeability rate of the PLA mesh mat is small, usually not exceeding 10%. Even under long-term immersion conditions, the water permeability still remains at a high level.

[0137] The permeability rate of coir fiber will decrease during the biodegradation process. According to research, when the coir fiber mesh mat 21 is under water erosion or immersion, the decrease in the permeability rate ranges from 15% to 30%, and it can still maintain basic water permeability.

[0138] (3) Surface Damage and Biodegradation

[0139] The water resistance and corrosion resistance of polylactic acid fiber enable it to perform well under the conditions of water erosion and long-term immersion, and its surface will not show obvious damage under these conditions. Research shows that the biodegradation rate of the PLA material is slow, and it usually takes 1 to 2 years to completely degrade in the environment.

[0140] The degradation rate of coconut coir fiber is relatively fast. Especially in a humid or water-soaked environment, the coconut coir fiber may undergo a significant degree of degradation within 1 to 2 years. The surface damage of coconut coir fiber after long-term soaking is relatively obvious. Some fibers will become loose, and the surface structure will experience slight wear.

[0141] Therefore, through reasonable material selection and design, the fiber mat 21 in this embodiment has strong durability and ecological friendliness. By means of appropriate material ratios and optimized structures, it can effectively resist the impacts of water flow scouring, long-term soaking, and biodegradation.

[0142] In summary, the plant fiber network unit 2 in this embodiment not only has excellent performance in aspects such as soil consolidation and anti-scouring, but also has a remarkable ecological restoration function. Through scientific design and reasonable material ratios, the plant fiber network unit 2 can effectively improve water quality, optimize soil structure, and enhance biodiversity, showing obvious ecological friendliness.

[0143] I. Improvement effect of the plant fiber network unit 2 on water quality

[0144] The plant fiber network unit 2 effectively improves water quality through its unique structure and material properties, which are mainly reflected in the following aspects:

[0145] (1) Reducing soil erosion:

[0146] The plant fiber network unit 2 can effectively consolidate the soil under different water flow conditions, reduce the scouring of water flow on the soil, and avoid the loss of nutrients in the soil. Through this mechanism, the plant fiber network unit 2 can reduce the sediment suspension in the water body, thereby improving the cleanliness of water quality.

[0147] (2) Water filtration function:

[0148] Plant fiber materials (such as coconut coir fiber, hemp fiber, polylactic acid fiber) have good adsorption and filtration capabilities, and can effectively intercept suspended particulate matter, pollutants, and harmful chemical substances in water. For example, when water flows through the fiber mat, the suspended particles will be captured by the fibers in the mat, reducing the pollutants entering the water body. Experimental data show that compared with traditional rigid slope protection structures, the plant fiber network unit 2 can more significantly reduce the concentration of suspended solids in water.

[0149] II. Optimization effect of the plant fiber network unit 2 on soil structure

[0150] The plant fiber network unit 2 not only helps with soil stability, but also can significantly improve the soil structure through the growth of roots and the binding effect of the mat:

[0151] (1) Soil consolidation and enhancement:

[0152] The plant roots in the plant fiber network unit 2 can penetrate deep into the soil, while enhancing the soil consolidation, preventing the soil from loosening or flowing away due to external forces. The fiber mesh mat 21 has a positive impact on the distribution of soil particle size, soil pore structure, soil compressive strength, etc., and can effectively avoid the impact of water flow on loose soil and reduce soil erosion.

[0153] (2) Improve the soil water retention capacity:

[0154] The fiber mesh mat 21 has good water permeability and water retention capacity, which can help the soil retain water and avoid soil drought. During the growth process of plant roots, the plant fiber network can also provide better support to help plant roots take root in relatively barren soil, thereby enhancing the soil water retention capacity.

[0155] (3) Increase the soil organic matter content:

[0156] Biodegradable materials (such as coconut shell fibers, hemp fibers) will gradually degrade and transform into organic matter during use, enrich the organic components in the soil, improve the soil fertility and microbial environment, and contribute to the formation of a benign soil ecosystem. Compared with traditional rigid slope protection technologies, the plant fiber network unit 2 can promote the accumulation of soil organic matter and improve the soil quality.

[0157] III. The promotion effect of the plant fiber network unit 2 on biodiversity

[0158] The plant fiber network unit 2 can promote the diversity of plant and animal populations by providing a suitable habitat and growth environment, thus promoting the restoration and development of the ecosystem:

[0159] (1) Promote plant growth and reproduction:

[0160] By providing support and protection for plant roots, the plant fiber network unit 2 can significantly improve the growth rate, root adhesion and coverage rate of plants under extreme conditions. Different plant species (such as cattail, reed, hygrophila, etc.) grow vigorously in the plant fiber network and have good ecological restoration ability. Compared with traditional rigid slope protection or concrete slope protection, the plant fiber network unit 2 provides a more relaxed and suitable growth environment, promoting plant diversity.

[0161] (2) Improvement of habitat and ecological chain:

[0162] The plant fiber network unit 2 provides a habitat for a variety of aquatic organisms, such as small insects, amphibians, fish, etc. The growth of plant roots can form a suitable habitat, providing a diverse environment required for biodiversity. Compared with traditional slope protection technologies, the ecological friendliness of the fiber mesh mat 21 can promote the restoration of biological habitats and thus enhance the biodiversity of the surrounding area.

[0163] (3) Ecosystem balance:

[0164] By providing support for plant growth and biological habitats, the plant fiber network unit 2 helps to restore the health and stability of the ecosystem. Compared with traditional rigid slope protection technologies, the plant fiber network unit 2 can not only effectively protect the soil, but also promote the natural restoration process of the surrounding area through the growth of plants and the restoration of the ecological chain.

[0165] IV. Comparison with traditional armor technologies

[0166] Compared with traditional rigid armor technologies (such as concrete slope protection, stone slope protection, etc.), as shown in Table 3, the plant fiber network unit 2 of this embodiment has significant advantages in ecological restoration.

[0167] Table 3

[0168]

[0169] The ecological restoration effect of the plant fiber network unit 2 is remarkable. Its advantages in improving water quality, optimizing soil structure, enhancing biodiversity, etc. far exceed those of traditional rigid armor technologies. By providing a good ecological support environment, this embodiment also shows great potential in ecological environmental protection and sustainable development. And it has strong ecological friendliness and environmental protection value, can effectively promote ecological restoration, and provide a feasible technical solution for future ecological projects.

[0170] The basic protection structure includes a flow deflector 3 arranged in the upstream area of the bridge foundation 1 and a bottom layer cushion 4 covering the bottom of the bridge foundation 1, and the fiber mesh cushion 21 is located above the bottom layer cushion 4. The flow deflector 3 is a semi-permeable flow deflector 3 made of corrosion-resistant polymer material. The corrosion-resistant polymer material is high molecular polyethylene (HDPE) or composite material, which has corrosion resistance, and the porosity of the flow deflector 3 is 20% - 40%, which can not only reduce the water flow impact force but also ensure the normal passage of water flow. The flow deflector 3 is installed in the upstream area of the bridge foundation 1, forming an angle of 30° - 45° with the water flow direction to disperse the water flow energy. The buried depth of the bottom of the flow deflector 3 into the soil body is 20 - 30 cm and is fixed by anchor piles to prevent the displacement of the plate body. The flow deflector 3 is used to reduce the water flow impact intensity. The function of the bottom layer cushion 4 is to prevent the water flow from scouring the soil body. The bottom layer cushion 4 is made of high-strength fiber material, with a thickness of 30 - 50 mm and a water permeability ≥ 90%. The high-strength fiber material is polyester fiber or fiberglass reinforced material. It covers the bottom of the bridge foundation 1 to avoid the phenomenon of soil body scouring.

[0171] I. Optimize the design of parameters such as the porosity, inclination angle, and installation depth of the flow deflector 3

[0172] (1) Porosity design: According to the water flow velocity and the hydraulic performance of the flow deflector 3, the porosity should be designed within a certain range to achieve the best water flow regulation effect. A higher porosity helps with the dispersion of water flow, but may affect the structural stability. Therefore, the porosity should be comprehensively considered in terms of water flow conditions, soil stability, and material strength.

[0173] Through experimental verification, at different water flow velocities, the porosity is optimized to ensure that the flow deflector 3 has sufficient water permeability and strength. For example, the porosity is designed between 20% - 40% to determine the optimal range.

[0174] (2) Inclination angle design: The inclination angle of the flow deflector 3 directly affects the dispersion effect of the water flow. A larger inclination angle can effectively guide the water flow, but may increase the water flow impact force. Through experimental testing, the inclination angle range is 15° - 45°. The selection of the inclination angle range should be based on the water flow conditions and the dispersion effect of the impact force. For example, at a higher water flow velocity, choosing a larger inclination angle helps improve the flow guiding effect, but it is necessary to ensure that excessive impact force is not generated. The design can be optimized by simulating the influence of the inclination angle on the flow velocity distribution under different water flow conditions.

[0175] (3) Installation depth design: The installation depth of the flow deflector 3 should be determined according to the water flow conditions, soil structure, and its anti - erosion performance. Being too shallow may not effectively guide the water flow, while being too deep may affect the structural stability or increase the construction difficulty. The selection of the installation depth is optimized based on the relative position of the water flow depth and the flow deflector 3. At different depths, the performance of the flow deflector 3 is tested, such as the impact force dispersion effect, stability, etc.

[0176] II. Data on the water flow velocity reduction rate and impact force dispersion effect of the flow deflector 3 under different water flow conditions

[0177] (1) Water flow velocity reduction rate

[0178] Experimental design: Measure the reduction of the water flow velocity of the flow deflector 3 under different water flow velocity conditions (such as 1 m / s, 3 m / s, 5 m / s). The experiment uses a flow velocity instrument to measure the velocity change of the water flow before and after passing through the flow deflector 3.

[0179] Data analysis: According to different water flow velocities and the parameters of the flow deflector 3 (such as porosity, inclination angle, installation depth, etc.), calculate the water flow velocity reduction rate. Provide the comparison data of the water flow velocity reduction rate under different configurations of the flow deflector 3.

[0180] Data example: For example, under the water flow condition of 1 m / s, the flow velocity is reduced by 50% after passing through the flow deflector 3; under the condition of 3 m / s, it is reduced by 45%; under the condition of 5 m / s, it is reduced by 40%.

[0181] (2) Impact force dispersion effect

[0182] Experimental design: By simulating the water flow impact force under different water flow velocity conditions (such as 1 m / s, 3 m / s, 5 m / s), measure the dispersion effect of the flow deflector 3 on the water flow impact force. Use an impact force sensor to test the change in the impact force when the water flow passes through the flow deflector 3.

[0183] Data analysis: Record the impact force dispersion effect under different water flow conditions, and compare the performance differences of the flow deflector 3 under different configurations (such as different porosity, inclination angle, and installation depth). Provide data on the influence of different design parameters on the impact force dispersion effect.

[0184] Data example: For example, under the water flow condition of 1 m / s, the impact force decreases by 30% after passing through the flow deflector 3; under the condition of 3 m / s, it decreases by 25%; under the condition of 5 m / s, it decreases by 20%.

[0185] The monitoring unit includes a drone inspection device and an embedded sensor installed in the fiber mesh pad 21.

[0186] The drone inspection device is used to regularly monitor plant growth, scour pit formation, the integrity of the foundation protection structure, and soil stability. The drone inspection device is equipped with a high-resolution camera, monitors the plant coverage through image recognition technology, and automatically generates reports on soil stability and plant growth conditions. The flight altitude of the drone inspection device is 50 - 100 m, and the image resolution of the drone inspection device is not less than 1080p.

[0187] The embedded sensor includes a soil displacement sensor, a water flow velocity sensor, and a plant root monitoring sensor. The soil displacement sensor is used to monitor the displacement of the soil to obtain the soil erosion situation. Especially in the water flow scouring test, it can provide effective monitoring of the soil body stability and erosion amount. The product model of the soil displacement sensor is Geokon6150P, and the accuracy is 0.1 mm; the water flow velocity sensor is used to monitor the water flow velocity in real time to obtain the water flow scouring intensity. The product model of the water flow velocity sensor is SonTek FlowTracker, and the error does not exceed ±2%; the product model of the plant root monitoring sensor is RootView TM , and its function is to detect the growth state of plant roots. The soil displacement sensor, the water flow velocity sensor, and the plant root monitoring sensor are respectively installed in the fiber mesh pad 21 of the plant fiber network unit 2, with 1 - 2 arranged per square meter, and denser arrangement in key areas.

[0188] The anti-scouring reinforcement method for the bridge foundation 1 using the above reinforcement system includes the following steps:

[0189] Step 1, Scour risk assessment: Divide the scour risk levels of bridge foundation 1 through a hydrological simulation tool, where the hydrological simulation tool is HEC-RAS software. The scour risk levels include high-risk areas, medium-risk areas, and low-risk areas. Output a risk assessment report and generate a scour intensity distribution map of bridge foundation 1;

[0190] Before using the hydrological model for scour risk assessment, it is necessary to collect hydrological, geological, and structural data related to bridge foundation 1. The scour risk assessment includes the following steps:

[0191] Step 11, Collect the topographic data, hydrological data, riverbed 5 material parameters, and bridge structure parameters of bridge foundation 1;

[0192] 1) Topographic data:

[0193] Collect the topographic and geomorphic data of the area where the bridge is located, including the riverbed 5 cross-section, pier geometry, and foundation burial depth.

[0194] Data source: Field survey (such as UAV aerial survey or laser scanning) or existing topographic maps.

[0195] Requirement: The cross-section spacing does not exceed 50m, and the cross-section density needs to be increased in key areas (near the piers).

[0196] 2) Hydrological data:

[0197] Collect data such as water flow, flow velocity, river water level changes, and flood frequency in the basin.

[0198] Data source: Meteorological and hydrological monitoring stations, or obtained through long-term observations.

[0199] Parameter requirements: Flow velocity range: 0.5 - 5m / s; Water depth range: 1 - 10m; Peak flood discharge: Take the design flow for a 50-year or 100-year return period.

[0200] 3) Riverbed 5 material parameters:

[0201] Collect riverbed 5 soil or rock samples to determine the physical and mechanical properties of the riverbed 5 soil mass.

[0202] Test items: Particle size distribution (D50, D90); Erosion resistance of the soil mass (critical shear stress).

[0203] Data requirements: Sandy soil: D50 = 0.1 - 2mm; Critical shear stress range: 0.5 - 2.0Pa.

[0204] 4) Bridge structure parameters:

[0205] Collect the geometric characteristics of the piers (shape, size, foundation type) and the pile foundation burial depth at the location of the bridge.

[0206] Requirement: Accurately measure the cross-sectional area, perimeter of the bridge pier, and the water-facing area in the flow direction.

[0207] Step 12: Based on the data collected in Step 11, construct a hydrological model of the river channel and the bridge in the HEC-RAS software and conduct simulation calculations.

[0208] (1) Establishment of the hydrological model

[0209] Input the geometric cross-section data of the river channel in HEC-RAS, including the shape, width, and water depth of the riverbed.

[0210] Determine the boundary conditions of the river channel. Upstream boundary: Input the flow rate variation process; downstream boundary: Input the water level control conditions (such as fixed water level or free outflow).

[0211] (2) Input of bridge foundation 1 parameters: Set the structure of bridge foundation 1 in the model, including the geometric shape, position, and pile foundation depth of the bridge pier. Define the hydrodynamic characteristics of bridge foundation 1, such as the flow-facing angle of the bridge pier, usually 0°, which needs to be adjusted if it is not directly facing the water.

[0212] (3) Setting of hydrodynamic conditions: Input parameters such as flow velocity, flow rate, and water depth, and define the flow rate variation process, such as the flood hydrograph during the flood season. Input the critical shear stress of the riverbed material for calculating the scour depth.

[0213] (4) Simulation calculations

[0214] Run the simulation using the HEC-RAS software and analyze the scour risk under different hydrodynamic conditions:

[0215] 1) Normal flow condition:

[0216] Simulate the flow velocity distribution, shear force, and scour trend under normal flow rate conditions.

[0217] Output: Flow velocity distribution map around bridge foundation 1 and variation of riverbed scour depth.

[0218] 2) Extreme flood condition:

[0219] Set the peak flood flow rate (such as the flood flow rate with a recurrence interval of 50 years or 100 years) and simulate the water flow impact and scour under extreme conditions.

[0220] Output: Maximum depth, range of the scour pit, and scour intensity distribution map around bridge foundation 1.

[0221] 3) Flow pattern analysis: Check the flow pattern near the bridge pier (such as vortex and recirculation areas), and focus on analyzing the water flow impact intensity on the water-facing side and downstream side of the bridge. Determine the high-risk areas of scour.

[0222] (5) Calculation of scour depth:

[0223] Calculate the total scour depth of Bridge Foundation 1 according to the scour formula: Total scour depth = Flow scour depth + Local scour depth of the structure + Riverbed evolution scour depth.

[0224] The range of scour depth output by simulation: 10 - 30 cm.

[0225] Step 13: Divide the scour risk level of Bridge Foundation 1 according to the simulation results in Step 12.

[0226] Conduct a quantitative analysis of the scour intensity and risk based on the simulation results:

[0227] (1) Scour area division:

[0228] High-risk area: Scour depth is greater than 20 cm and water flow velocity is greater than 4 m / s;

[0229] Medium-risk area: Scour depth is 10 - 20 cm and water flow velocity is 2 - 4 m / s;

[0230] Low-risk area: Scour depth is less than 10 cm and water flow velocity is lower than 2 m / s.

[0231] (2) Risk level assessment:

[0232] Mark Bridge Foundation 1 in zones, divide the scour risk levels (high, medium, low); Output a risk assessment report and generate a scour intensity distribution map of Bridge Foundation 1.

[0233] (3) Data verification and optimization

[0234] 1) Verify the simulation results: Compare the scour phenomena of the soil around the bridge, the measured data of historical monitoring records with the simulation results to verify the model accuracy. Adjust the model inputs such as the parameters of the critical shear stress of the riverbed material to improve the reliability of the simulation results.

[0235] 2) Optimize the scour protection plan: Determine the laying range of the fiber mesh mat 21 and the layout position of the hydrodynamic energy dissipation device according to the scour risk distribution map. Strengthen the protection measures in high-risk areas, such as increasing the density of the flow deflector 3 or thickening the covering layer of the mesh mat.

[0236] (4) Output and report

[0237] Generate a scour risk assessment report, including the following contents: Water flow velocity distribution map; Scour depth distribution map; Division results of high, medium, and low-risk areas; Scour risk analysis conclusion.

[0238] Provide basic data for subsequent construction, including the laying range of the fiber mesh mat 21, the layout parameters of the hydrodynamic energy dissipation device, and construction suggestions for key protection areas.

[0239] In this step, quantitative analysis of the scour intensity and risk areas of the bridge foundation 1 is carried out through a hydrological simulation tool, which provides a scientific basis for the optimal design of the fiber mesh mat 21 and the hydrodynamic energy dissipation device, ensuring the efficiency and reliability of the anti-scour reinforcement plan.

[0240] Step 2: Laying the fiber mesh mat 21: According to the scour intensity distribution map of the bridge foundation 1 in Step 1, the fiber mesh mat 21 is selected to be laid in the high-risk area. The coverage area of the fiber mesh mat 21 exceeds 50% of the width of the bridge foundation 1. The edges of the fiber mesh mat 21 are fixed by anchor bolts or steel piles, where the spacing of the anchor bolts or steel piles does not exceed 1 m, the diameter of the anchor bolts is 10 - 20 mm, and the penetration depth ≥ 50 cm. The penetration depth is not less than 50 cm.

[0241] Step 3: Planting plants: The planting substrate 22 is filled on the fiber mesh mat 21 described in Step 2. The thickness of the planting substrate 22 is 50 - 100 mm to cover the surface of the fiber mesh mat 21. 200 - 300 plant seeds are sown per square meter of the fiber mesh mat 21. After planting, water is sprayed to keep the soil moist and ensure the plant growth conditions: water depth: 0 - 0 cm; soil moisture content: ≥ 30%. The plant seeds include the seeds of cattail, reed or hygrophila.

[0242] Step 4: Arranging the flow deflector 3: The flow deflector 3 with a porosity of 20% - 40% is arranged in the upstream area of the bridge foundation 1 to ensure its stability and flow diversion function. The flow deflector 3 forms an angle of 30° - 45° with the water flow direction and is fixed by anchor piles. The burial depth of the flow deflector 3 should be greater than 20 cm, and the inclination angles are kept consistent.

[0243] Step 5: Data monitoring: The water flow scour data and the data of the foundation protection structure are collected through the UAV inspection device. The inspection frequency of the UAV inspection device is once a month to check whether the plant coverage rate exceeds 80%. When the plant coverage rate is lower than 50%, replanting is required. Soil displacement sensors, water flow velocity sensors and plant root monitoring sensors are installed in the fiber mesh mat 21 to obtain the data of soil displacement, water flow velocity and plant root growth status. The data collected by the UAV inspection device, soil displacement sensors, water flow velocity sensors and plant root monitoring sensors are transmitted to the central monitoring system.

Claims

1. A bridge foundation anti-scour reinforcement system based on plant fiber network, characterized in that: It includes a plant fiber network unit and a foundation protection structure. The plant fiber network unit includes a fiber mesh mat covering the periphery of the bridge foundation and a planting matrix covering the fiber mesh mat. A three-dimensional grid in a honeycomb or staggered grid shape is provided in the fiber mesh mat. The foundation protection structure includes a guide plate arranged in the upstream area of ​​the bridge foundation and a bottom layer protective pad covering the bottom of the bridge foundation, and the fiber mesh mat is located above the bottom layer protective pad.

2. The reinforcement system according to claim 1, characterized in that: It also includes a monitoring unit, which includes an unmanned aerial vehicle inspection device and an embedded sensor installed in a fiber mesh pad. The unmanned aerial vehicle inspection device is used to regularly monitor plant growth, scour pit formation, foundation protection structure integrity and soil stability. The flight altitude of the unmanned aerial vehicle inspection device is 50 to 100 meters, and the image resolution of the unmanned aerial vehicle inspection device is not less than 1080p; the embedded sensors include soil displacement sensors, water flow velocity sensors and plant root monitoring sensors.

3. The reinforcement system according to claim 1, characterized in that: The fiber mesh pad is made of biodegradable natural fiber material or high-strength synthetic fiber, the biodegradable material includes coconut shell fiber or hemp fiber, the high-strength synthetic fiber includes polylactic acid fiber, the mesh diameter of the fiber mesh pad is 5-20mm, the tensile strength is ≥20MPa, and the water permeability is ≥90%. The planting matrix is ​​a mixture of river sand, humus and organic fertilizer, wherein the particle diameter of the river sand is 0.1-2mm, the humus contains ≥10% organic matter, 3kg of nitrogen, phosphorus and potassium fertilizers are added to each cubic meter of planting matrix, the thickness of the planting matrix is ​​50-100mm, and the height of the three-dimensional grid is 10-20mm.

4. The reinforcement system according to claim 1, characterized in that: The guide plate is a semi-permeable guide plate made of corrosion-resistant polymer material, the corrosion-resistant polymer material is polymer polyethylene or a composite material, and the porosity of the guide plate is 20% to 40%, forming an angle of 30° to 45° with the water flow direction, the bottom of the guide plate is buried in the soil at a depth of 20 to 30 cm, and is fixed by anchor piles.

5. The reinforcement system according to claim 1, characterized in that: The bottom layer protective pad is made of high-strength fiber material, with a thickness of 30-50 mm and a water permeability of ≥90%. The high-strength fiber material is polyester fiber or glass fiber reinforced material.

6. A method for strengthening bridge foundation against scour using the reinforcement system according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1, scour risk assessment: divide the scour risk level of the bridge foundation into high-risk area, medium-risk area and low-risk area, output the risk assessment report, and generate the scour intensity distribution map of the bridge foundation; Step 2, laying of fiber mesh mats: according to the scour intensity distribution map of the bridge foundation in step 1, fiber mesh mats are laid in high-risk areas, the coverage area of ​​the fiber mesh mats exceeds 50% of the width of the bridge foundation, and the edges of the fiber mesh mats are fixed by anchors or steel piles, wherein the spacing between the anchors or steel piles does not exceed 1m, and the depth of the anchors or steel piles is not less than 50cm; Step 3, plant planting: filling the fiber mesh mat in step 2 with a planting matrix and sowing plant seeds; Step 4, guide plate arrangement: a guide plate with a porosity of 20% to 40% is arranged in the upstream area of ​​the bridge foundation, and the guide plate forms an angle of 30° to 45° with the water flow direction and is fixed by anchor piles; Step 5, data monitoring: Install embedded sensors in the fiber mesh mat and use the embedded sensors and drone inspection devices to monitor soil stability and plant growth in real time.

7. The method according to claim 5, characterized in that The scour risk assessment described in Step 1 includes the following steps: Step 11, collecting topographic data, hydrological data, riverbed material parameters and bridge structure parameters of the bridge foundation; Step 12, constructing a hydrological model based on the data collected in step 11, and performing simulation calculations to obtain simulation results; Step 13, classifying the scour risk level of the bridge foundation according to the simulation results of step 12.

8. The method according to claim 5, characterized in that The scouring depth in the high-risk area is greater than 20cm, and the water flow speed is greater than 4m / s; the scouring depth in the medium-risk area is 10-20cm, and the water flow speed is 2-4m / s; the scouring depth in the low-risk area is less than 10cm, and the water flow speed is less than 2m / s.

9. The method according to claim 5, characterized in that The thickness of the planting matrix in step 3 is 50-100 mm, and 200-300 plant seeds are sown per square meter, and the plant seeds include seeds of cattail, reed or water sedge.

10. The method according to claim 5, characterized in that The inspection frequency of the drone inspection device described in step 5 is once a month, and replanting is required when the plant coverage rate is less than 50%.

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