An ecological slope protection structure and construction method

Abstract

This invention relates to an ecological slope protection structure and construction method, comprising: a roadbed main body, a foundation bearing and counterweight consolidation base layer, a gradient permeable drainage layer, an ecological vegetation soil stabilization layer, and a drainage system. The foundation bearing and counterweight consolidation base layer includes a seepage-proof isolation layer, an inner-edged sandwich embankment, and a counterweight retaining wall. The seepage-proof isolation layer is located at the bottom of the roadbed main body and in the inner-edged area of ​​both sides of the slope. The seepage-proof isolation layer includes a non-expansive soil waterproof isolation layer on the base surface and a non-expansive clay inner-edged structure in the inner-edged area of ​​both sides of the roadbed slope. The inner-edged sandwich embankment adopts an inner-edged sandwich structure. The counterweight retaining wall is constructed at the toe of both sides of the roadbed slope. The gradient permeable drainage layer is fully laid on the slope outside the seepage-proof isolation layer. The ecological vegetation soil stabilization layer is located outside the gradient permeable drainage layer and includes a porous permeable skeleton fixed on a gravel soil structure layer. The drainage system includes a slope toe drainage ditch and a slope rapid flow channel.

Description

Technical Field

[0001] This invention belongs to the field of road engineering technology, and specifically relates to an ecological slope protection structure and construction method. Background Technology

[0002] When expanding highway networks in tropical monsoon climate zones and river basins, newly constructed roads are located in areas with high embankments and periodic flooding, making them susceptible to water erosion and wind and wave erosion.

[0003] First, there is an atmospheric influence depth of about 1m to 2m on the top and side slopes of the roadbed. Surface shrinkage cracks formed during the dry season will become channels for rainwater to infiltrate during the rainy season, destroying the optimal moisture content of the deep filler and even forming water pockets inside, triggering hidden deep landslides.

[0004] Secondly, if the surface filler of the roadbed has a high silt content and lacks cohesive particles, during extreme rainfall or flooding and receding stages, surface runoff will quickly carry away the fine sand and silt, forming gullies on the slope and shoulder, or even forming local hollowing phenomena similar to rat holes, causing serious subsidence at the edges of the roadbed.

[0005] Third, during the flood season, water level differences are easily formed on both sides of the roadbed, generating extremely fast vortices or backflows at bridges, culverts, cone slopes, and abutments, causing the slopes to tend to slide outwards.

[0006] Fourth, most existing technologies are designed for roadbed slopes in general areas and are not well adapted to the special environment of areas subject to periodic flooding. In particular, for areas with high roadbed filling heights and multiple effects such as seasonal periodic flooding, water erosion, wind and wave erosion, and wet-dry cycles, traditional ecological slope protection technologies are difficult to meet engineering requirements.

[0007] Therefore, how to provide an ecological slope protection structure and construction method is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0008] While traditional rigid structures such as full-slope concrete protection or masonry rubble masonry can block water, their construction and maintenance costs are extremely high throughout their entire life cycle. They also cannot adapt to slight settlement of the roadbed and damage biodiversity along the route. This invention provides an ecological slope protection structure and construction method. By constructing a gradient permeability protection system consisting of a "surface ecological vegetation retention layer + middle gravel soil drainage and permeable layer + foundation bearing and counter-pressure consolidation base layer", it effectively solves the problems of instability, cracking and erosion of high-fill roadbeds in water-sensitive areas under dry-wet cycles, periodic flooding and flow erosion, and achieves the synergistic evolution of ecological slope protection and roadbed structural mechanical stability.

[0009] To solve the above technical problems, the present invention includes the following technical solutions:

[0010] An ecological slope protection structure includes, from the inside out, a roadbed main body, a foundation bearing and counterweight consolidation base layer, a gradient permeable drainage layer, an ecological vegetation soil stabilization layer, and a drainage system located at the slope toe; wherein, the foundation bearing and counterweight consolidation base layer includes a seepage-proof isolation layer, an inner-edged sandwich embankment, and a counterweight retaining wall.

[0011] The seepage-proof isolation layer includes a 0.5-1.0m thick non-expansive soil waterproof isolation layer set on the surface of the cleared base and a non-expansive clay inner edging structure located in the inner edging area on both sides of the roadbed slope; the inner edging sandwich embankment adopts an inner edging sandwich structure; the counterweight revetment is constructed at the toe of the slope on both sides of the roadbed, the filling height of the counterweight revetment is not less than half of the total filling height of the roadbed and is higher than the local periodic highest flood level, and the horizontal width is not less than 2.0m;

[0012] The gradient permeable drainage layer is fully laid on the surface of the roadbed slope, including a 100g / m² reverse filter geotextile laid along the slope surface, and a 200~400mm thick highly permeable gravel soil structure layer built on the outside of the reverse filter geotextile. A longitudinal PVC pipe is buried at the bottom of the gravel soil structure layer and the junction with the counterweight protection road.

[0013] The ecological vegetation soil stabilization layer includes a porous permeable skeleton fixed on the upper part of the gravel soil structure layer. The porous permeable skeleton is filled with ecological planting soil and planted with ecological vegetation with well-developed root systems.

[0014] The drainage system includes slope toe drainage ditches and slope rapid flow channels.

[0015] Furthermore, the inner-edged sandwich embankment adopts an inner-edged sandwich structure. The cross-section of the inner-edged sandwich embankment is filled with waterproof and seepage-resistant non-expansion clay as the inner edging within a horizontal width of 1.5m to 2.0m from the slope line. The interior of the cross-section is filled with weakly expansive soil or ordinary soil. The CBR value of the non-expansion clay is not less than 4%, and the compaction degree is not less than 95%.

[0016] Furthermore, the counterweight retaining wall adopts a stepped structure, with each step being 2m to 3m high and 2m to 3m wide, and the slope ratio not steeper than 1:1.5; the surface of the counterweight retaining wall is provided with an outward transverse slope of 2% to 3%, and a drainage ditch is provided at the toe of the slope; the fill material of the counterweight retaining wall is topsoil or excavated excavated material from the foundation pit.

[0017] Furthermore, the gravel soil structure layer in the gradient infiltration drainage layer has a thickness of 200mm~400mm, and the mass percentage of gravel with a particle size of 5mm~40mm in its filler gradation is 55%~65%, with the remainder being medium and coarse sand, and the permeability coefficient is controlled at 1×10⁻²~1×10⁻³ cm / s; the slope toe drainage pipe is a longitudinally perforated corrugated pipe with a pipe diameter of not less than 110mm and an opening rate of more than 15%, and the pipe is wrapped with a reverse filter non-woven fabric.

[0018] Furthermore, the porous permeable framework in the ecological vegetation soil stabilization layer is a sand-free porous permeable concrete hexagonal grid or layered ecological bags. The porosity of the sand-free porous permeable concrete hexagonal grid is controlled at 20%~30%, and the compressive strength is not less than 15MPa. The ecological planting soil is a mixture of local topsoil, humus, and organic fertilizer in a volume ratio of 7:2:1. The ecological vegetation includes mixed herbaceous plants and shrubs. The herbaceous plants are selected from at least one of Bermuda grass, Bahia grass, and lemongrass, and the shrubs are selected from at least one of oleander, Amorpha fruticosa, Ligustrum lucidum, and Magnolia multiflora.

[0019] Furthermore, the gradient infiltration drainage layer is also provided with transverse drainage blind ditches. The transverse drainage blind ditches are set every 3m to 5m along the slope height, with a slope of not less than 2%. The outlet extends to the drainage ditch at the toe of the slope. The transverse drainage blind ditches are filled with gravel and wrapped with reverse filter geotextile.

[0020] Furthermore, for the bridge and culvert cone slope and the slope behind the abutment, gabion protection is added outside the gradient permeability drainage layer. The gabion protection is made of galvanized iron wire mesh with a size of 1m×1m×0.5m and filled with boulders with a particle size of 10cm~30cm. A reverse filter geotextile is installed between the gabion protection and the gradient permeability drainage layer.

[0021] Furthermore, in areas where the water depth exceeds 2m, the lower part of the ecological slope protection structure is equipped with a 1m to 2m high rubble masonry slope protection, and the upper part is equipped with an ecological vegetation soil stabilization layer; a 5cm to 10cm gap is reserved between the rubble masonry for plant growth.

[0022] Furthermore, the thickness of the gravel soil structure layer in the intermediate gravel soil drainage permeable layer is 200mm~400mm, and the mass percentage of gravel with a particle size of 5mm~40mm in its filler gradation is 55%~65%, with the remainder being medium and coarse sand, and the permeability coefficient is controlled at 1×10⁻²~1×10⁻³ cm / s.

[0023] Furthermore, the porous permeable framework in the surface ecological vegetation stagnant layer is a sand-free porous permeable concrete hexagonal grid or stacked ecological bags. The porosity of the sand-free porous permeable concrete hexagonal grid is controlled at 20%~30%, and the compressive strength is not less than 15MPa. The ecological vegetation includes mixed herbaceous plants and shrubs. The herbaceous plants are selected from at least one of Bermuda grass, Bahia grass, and lemongrass. The shrubs are selected from at least one of oleander, Amorpha fruticosa, Ligustrum lucidum, and Magnolia multiflora.

[0024] This invention also provides a construction method for an ecological slope protection structure, comprising:

[0025] Step S1, Foundation Treatment and Bearing Capacity Replacement: Clear the original ground surface. The clearing thickness should be no less than 0.3m for general road sections and no less than 0.5m for paddy fields or soft soil sections. After clearing, use permeable replacement materials such as quarry, crushed stone, or coarse sand for replacement treatment, and compact until the foundation bearing capacity is no less than 200kPa.

[0026] Step S2: Filling the seepage barrier layer and the embankment core layer: Fill the base surface with non-expansive clay or seepage barrier gravel soil with a thickness of 0.5m~1.0m as a seepage barrier layer, and simultaneously use the inner edge sandwich process to fill and compact the embankment core layer in layers.

[0027] Step S3: Simultaneous construction of slope repair and counterweight retaining wall: 0.5m of extra-wide filling is carried out on each side of the embankment. After filling to the top, mechanical slope cutting and compaction are carried out to control the slope ratio to be no steeper than the predetermined value, such as no steeper than 1:2. At the same time, the cleared soil is used to spread and compact the counterweight retaining wall in layers on both sides of the slope toe.

[0028] Step S4: Constructing a mid-layer gravel soil drainage and permeable layer: Fully lay reverse filter geotextile on the slope, then spread a gravel soil structural layer on its surface, and pre-embed longitudinal perforated corrugated pipes in the transverse drainage blind ditch inside the slope toe counterweight protection road. The gravel soil structural layer is constructed in layers.

[0029] Step S5, Surface ecological slope protection construction and vegetation greening: Install a porous permeable frame on the gravel soil layer, fill the frame grid with planting soil and spray mixed vegetation grass seeds or transplanted turf; the planting soil is made by mixing local topsoil, humus and organic fertilizer in a volume ratio of 7:2:1.

[0030] Step S6, Full Life Cycle Monitoring and Environmental Dynamic Feedback: Settlement observation piles and three-dimensional displacement markers are symmetrically installed in the center of the embankment, shoulder and counterweight retaining wall. Settlement deformation and slope moisture content are monitored regularly before and after the rainy season, during the rising and receding water stages. Based on the data feedback, seepage anomalies are dynamically reinforced by grouting or drainage holes are added. After the rainy season, a falling weight deflectometer (FWD) is used to detect the deflection of the roadbed top and to analyze the convergence of settlement displacement.

[0031] Furthermore, in step S2, the non-expansive clay used in the inner edge sandwich process is non-expansive clay or weakly expansive clay with a CBR value of not less than 4%; for soil materials with strong expansibility, 5% to 8% lime is added for improvement.

[0032] Furthermore, the counter-pressure protection road described in step S3 adopts a stepped structure, with each step being 2m to 3m high and 2m to 3m wide, and the slope ratio not steeper than 1:1.5; the surface of the protection road is provided with an outward transverse slope of 2% to 3%, and a drainage ditch is provided at the toe of the slope.

[0033] Furthermore, in step S4, a transverse drainage ditch is installed every 3m to 5m along the slope height. The transverse drainage ditch is filled with gravel and wrapped with reverse filter geotextile. The slope of the transverse drainage ditch is not less than 2%, and the outlet extends into the drainage ditch at the toe of the slope.

[0034] Furthermore, the planting density of herbaceous plants in step S5 is 15~20g / m², and the planting density of shrubs is 1~2 plants / m²; turf can also be directly transplanted from the field and laid on top.

[0035] Furthermore, in step S6, a cross section is arranged every 100m to 150m for the settlement displacement observation points, and three observation points are set in each cross section, located 1m inward from the center pile of the roadbed and the slope lines on both sides, respectively; a soil moisture monitoring point is arranged every 2m along the slope height, with depths of 0.5m, 1m and 2m, respectively.

[0036] Furthermore, construction will be carried out during the dry season, with all protective works completed before the rainy season; during the rainy season, patrols will be strengthened, and sandbags will be used to temporarily reinforce severely eroded areas.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] (1) The ecological slope protection structure provided by the present invention effectively solves the three major technical problems faced by roadbeds in tropical flood-prone areas, such as dry-wet cycle cracking, surface scouring and hollowing, and seepage instability, through the synergistic effect of the three-level protection system. Engineering practice shows that the slope settlement using this method is reduced by more than 45% compared with the traditional scheme, and no gully or landslide phenomenon occurs, which significantly improves the ability to resist water damage.

[0039] (2) The ecological slope protection structure provided by the present invention makes full use of the engineering waste as the back pressure protection filler, reducing the cost of soil transportation and soil extraction; the inner edging process greatly saves the amount of high-quality impermeable soil; compared with the full masonry protection, the overall cost is reduced by 15%-30%, and the later maintenance cost is reduced by more than 50%, with outstanding engineering economics.

[0040] (3) The ecological slope protection structure provided by the present invention uses native plants to construct vegetation communities, restores the ecological function of the slope, and provides habitats for local plants and animals; it reduces the use of high-carbon building materials such as cement and gravel, which is in line with the concept of green and low-carbon development and is environmentally friendly.

[0041] (4) The ecological slope protection structure provided by the present invention will improve the slope’s erosion resistance and overall stability year by year as the plant roots grow and extend; even if there is slight erosion damage in some areas, the vegetation can recover naturally, reducing the intensity of artificial maintenance and having strong self-repair ability. Attached Figure Description

[0042] Figure 1 This is a schematic cross-sectional view of an ecological slope protection structure according to an embodiment of the present invention;

[0043] Figure 2 This is a schematic diagram of the stepped structure of the counterpressure retaining wall in an ecological slope protection structure according to an embodiment of the present invention.

[0044] Figure 3 This is a schematic diagram of the stepped structure of the bridge and culvert cone slope protection gabion in an ecological slope protection structure according to an embodiment of the present invention.

[0045] In the picture,

[0046] 1-Subgrade main body, 2-Imperible isolation layer, 3-Gradient permeable drainage layer, 4-Ecological vegetation soil stabilization layer, 5-Counterweight protection road, 6-Drainage system, 61-Slope toe drainage ditch, 62-Slope rapid flow channel, 7-Slope toe drainage culvert, 8-Transverse drainage blind ditch, 9-Gabion protection, 91-Galvanized wire mesh cage, 92-Rock block. Detailed Implementation

[0047] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides an ecological slope protection structure and construction method based on the present invention. The advantages and features of the present invention will become clearer from the following description.

[0048] Design Concept

[0049] This invention proposes the concept of a "breathable slope," designing the slope as an open system capable of autonomously regulating its internal moisture. During flood season, the surface vegetation slows down water erosion, the middle gravel layer rapidly drains infiltrated rainwater, and the bottom counterweight retaining wall resists softening at the slope toe. During receding water season, accumulated water inside the subgrade is quickly discharged through the drainage layer, preventing the formation of water pockets and seepage damage. Through the synergistic effect of the three-layer structure, the slope maintains a stable moisture content throughout the wet-dry cycle.

[0050] The following is combined with Figures 1 to 3 The ecological slope protection structure of the present invention is described in detail.

[0051] Example 1

[0052] Please refer to Figures 1 to 3 An ecological slope protection structure includes, from the inside out, a main roadbed 1, a foundation bearing and counterweight consolidation base layer, a gradient permeable drainage layer 3, an ecological vegetation soil stabilization layer 4, and a drainage system 6 located at the slope toe; wherein, the foundation bearing and counterweight consolidation base layer includes a seepage-proof isolation layer 2, an inner-edged sandwich embankment, and a counterweight retaining wall 5. Specifically:

[0053] (1) Foundation bearing capacity and counter-pressure consolidation base course

[0054] 2. Impermeable isolation layer: After clearing the surface, fill the base with 0.5~1.0m thick non-expansive clay or impermeable gravel soil with a compaction degree of ≥95% to completely block the upward intrusion of ground capillary water and groundwater during flood season into the core fill of the roadbed.

[0055] Inner-edged sandwich embankment: To address the shortage of high-quality impermeable soil in the area, the embankment cross-section is divided into a core zone and an edging zone. The 2.0m wide edging zone on both sides uses non-expansive clay with good impermeability, while the core zone can use locally abundant weakly expansive soil. Both are filled and compacted simultaneously in layers, which not only ensures the impermeability of the slope but also significantly reduces material costs.

[0056] Counterweight retaining wall: Construct counterweight retaining walls 5 with a width ≥ 2.0m, a height ≥ 1 / 2 of the embankment, and higher than the historical highest flood level on both sides of the slope toe. Priority should be given to using engineering clearing and excavation waste. Counterweight retaining wall 5 not only provides strong lateral anti-sliding force, but also directly shields the effects of atmospheric wet and dry cycles within a depth range of 1~2m, fundamentally solving the problem of surface shrinkage cracks.

[0057] (2) Middle gravel soil drainage permeable layer

[0058] A 100g / m² reverse filter geotextile is laid on the repaired and compacted slope surface to prevent fine soil particles from entering the drainage layer and causing blockage.

[0059] Spread a 200-400mm thick layer of graded gravelly soil, of which 55%-65% is 5-40mm gravel and the remainder is medium-coarse sand, with a permeability coefficient controlled at 1×10⁻²~1×10⁻³cm / s. This layer can quickly drain water from the slope and internal seepage, while also providing growth space for vegetation roots.

[0060] A longitudinal blind ditch is installed inside the counterweight retaining wall at the toe of the slope. A Φ110mm perforated corrugated pipe is buried, wrapped with permeable non-woven fabric, and then connected to the roadbed drainage system to form a complete drainage network. The drainage system 6 includes a slope toe drainage ditch 61 and a slope rapid flow channel 62.

[0061] (3) Surface ecological vegetation stagnant layer

[0062] Large-diameter rubble is used as a rigid framework with a porosity of 20%~30% and a compressive strength of ≥15MPa. It can resist the erosion of high-speed water flow and provide support for plant growth.

[0063] Biodegradable eco-bags are embedded in the gaps between the rubble stones. The bags are filled with ecological planting soil, which is a mixture of local clay, humus, peat, water-retaining agent, and slow-release fertilizer, to provide nutrients for vegetation growth.

[0064] Local plants with deep root systems, tolerance to flooding, and drought were selected, and a mixed sowing method of grasses and shrubs was used to construct a composite vegetation community. Herbaceous plants such as lemongrass and bahia grass have well-developed root systems that can quickly cover the slope surface; shrubs such as privet and magnolia multiflora have root systems that reach a depth of 1-2 meters, penetrating the drainage layer and embedding themselves into the main body of the roadbed like "living anchors," significantly improving the overall stability of the slope.

[0065] Specifically, for the bridge and culvert cone slopes and the slopes behind abutments, gabion protection 9 is added outside the gradient permeability drainage layer 3. The gabion protection 9 is made of galvanized wire mesh cages 91, with dimensions of 1m×1m×0.5m, and filled with 10cm~30cm boulders 92. A reverse filter geotextile is installed between the gabion protection 9 and the gradient permeability drainage layer 3. In areas where the flooding depth exceeds 2m, a 1m~2m high rubble masonry slope protection is installed at the bottom of the ecological slope protection structure, and an ecological vegetation soil stabilization layer 4 is used on top. A 5cm~10cm gap is left between the rubble masonry for plant growth.

[0066] Please continue to refer to this. Figures 1 to 3 This embodiment also provides a construction method for ecological slope protection structures, which specifically includes the following steps:

[0067] (1) Step 1: Base surface cleaning and bearing capacity targeted treatment

[0068] More than 40% of a newly constructed road is located in a low-lying, flood-sensitive area with periodic water level fluctuations. Geological exploration shows that the surface topsoil and paddy field silt layers are 0.5m to 1.0m thick.

[0069] Clearing work: Tracked bulldozers and excavators are used to clear the surface to a depth of 0.3m on general road sections, and the clearing depth is increased to 0.5m on rice paddy sections with poor geological conditions.

[0070] Subgrade Replacement: After clearing the surface, direct filling is strictly prohibited. The exposed weak-bearing subgrade surface should be compacted. If springiness is caused by a high groundwater level, 100mm-300mm diameter slag should be dumped to isolate groundwater. Large stones should be placed at the bottom, and small and medium-sized stones should form an interlocking stabilizing layer on top. A 100mm-200mm layer of medium-coarse sand or graded crushed stone should be laid on top and compacted using a 22-ton heavy vibratory roller until the subgrade bearing capacity is consistently above 200kPa as measured by static cone penetration testing or sand cone method.

[0071] (2) Step 2: Filling of the seepage-proof isolation layer 2 and core water control of the inner edge

[0072] In order to completely prevent underground capillary water from infiltrating the core fill of the roadbed during the flood season, a high-performance seepage-proof isolation layer 2 must be added.

[0073] Construction of the seepage-proof isolation layer 2: On the surface of the qualified replacement base, fill two layers of non-expansive high-quality clay (or seepage-proof gravel soil layer) with a total thickness of 0.6m. The CBR value of the fill material must be ≥4%, and the compaction degree must be strictly controlled above 95%.

[0074] Inner-edge sandwich filling method: Given the limited availability of qualified non-expansive soil resources at the engineering site, this invention adopts an inner-edge selection and filling process. During the overall layered filling of the embankment, the roadbed cross-section is divided into a core area and two side slope edging areas. The 2.0m horizontal width inward from the slope line on both sides of the slope serves as the edging protection zone. The filling material in this zone must be strictly selected from non-expansive clay with excellent impermeability, strong water stability, and excellent water permeability index. The core area can use relatively common weakly expansive soil or ordinary soil from the local area. The edging soil on both sides and the filling material in the core area must be laid and compacted simultaneously in layers, with the loose layer thickness strictly controlled within 30cm to ensure tight interlocking and prevent the formation of longitudinal seepage channels at the interface.

[0075] (3) Step 3: Coordination of ultra-wide filling, finishing and compaction with large-volume spoil counterweight protection.

[0076] High embankment roadbeds (in this example, the embankment height is generally 6m to 9m) have a great tendency to expand and deform laterally under the action of gravity and water flow.

[0077] Extra-wide compaction: Intentionally fill an area 0.5m wider than the design slope line on each side. During layered compaction, the roller tracks must cover the extra-wide area to ensure that the compaction degree at the edge of the slope is completely consistent with the interior (ensuring a compaction degree ≥96%).

[0078] Precise slope trimming: After filling to the top, an excavator with a GPS slope control system is used to trim the slope from top to bottom, removing loose surface soil and precisely controlling the slope ratio at a stable upper limit of 1:2. Then, a plate vibratory tamper or slope compactor is used to perform special compaction treatment on the trimmed slope surface, making the surface soil of the slope compact and dense.

[0079] Counterweight retaining walls: While repairing the slope, the topsoil, excavated soil, and excavated material from nearby culverts, which were cleared and piled up in step one, are transported to the outer side of the slope toe. Counterweight retaining walls, 2.5m wide and 4.0m high (approximately half the total roadbed height, ensuring they exceed the highest historical flood level), are symmetrically constructed on both sides of the slope toe. The counterweight retaining walls are mechanically leveled in layers and compacted by bulldozer tracks, which not only provides significant lateral anti-sliding mechanical balance but also directly shields the internal embankment from the physical impact of alternating wet and dry conditions on the 1.5m depth of atmospheric influence.

[0080] (4) Step 4: Install a "breathable" middle layer drainage and permeable system

[0081] To eliminate the head difference and seepage damage generated inside the roadbed during the receding water stage, a gradient infiltration drainage channel is constructed.

[0082] Construction of gravel soil drainage layer: On the outside of the slope, a 300mm thick layer of graded gravel soil (60% gravel with a particle size of 5mm~40mm and the remainder medium and coarse sand) is laid manually with the help of small machinery. This layer has an extremely high permeability coefficient.

[0083] Blind Drainage and Underground Pipe Network: At the intersection of the gravel soil layer and the slope toe counterweight retaining wall 5, a transverse drainage blind drain 8 is excavated. A rigid PVC high-density perforated corrugated underground pipe (diameter Φ110mm, perforation rate greater than 15%) is laid at the bottom of the drain. The outer circumference of the underground pipe is wrapped with 100g / m² permeable non-woven fabric and connected to the drainage pipe, forming a gradient infiltration drainage layer 3. This structure ensures that during heavy rain or receding water periods, water within and on the surface of the slope can quickly collect along the gravel soil and drain through the slope toe drainage pipe 7, preventing it from accumulating and remaining on the roadbed surface.

[0084] (5) Step 5: Multifunctional surface ecological slope protection and soil stabilization and vegetation community establishment

[0085] The outermost layer serves to resist direct rainwater erosion and beautify the environment along the route, achieving ecological and low-carbon functions.

[0086] Installation of porous concrete framework: On the surface of the gravelly soil layer, a precast, sand-free, porous, permeable concrete hexagonal grid (porosity controlled at 20%~30%, compressive strength ≥15MPa) is laid. The framework is interlocked with graded pins to form an integrated rigid erosion-resistant "mesh armor".

[0087] Eco-bag and planting soil preparation: Eco-bags made of biodegradable geotextile are layered and embedded inside a hexagonal grid. The filling ratio inside the bag is: 75% local clay + 15% organic humus + 8% peat moss + 2% high-efficiency composite water-retaining agent and slow-release fertilizer.

[0088] Tropical monsoon vegetation construction: Considering the extreme climate of the area, characterized by scorching heat during the dry season and prolonged flooding during the rainy season, grass species with highly developed root systems and tolerance to both flooding and drought, such as lemongrass, bahiagrass, and bermudagrass, were selected and mixed with shrubs such as privet and magnolia multiflora for spraying. Lemongrass's vertical root system, reaching depths of 1-2 meters, acts like a living anchor, penetrating the porous framework and mid-layer gravelly soil, firmly embedding itself in the inner embankment soil, forming a perfect "ecological-mechanical" composite reinforcement.

[0089] (6) Step Six: Digital Monitoring and Full Lifecycle Adaptive Maintenance

[0090] Monitoring network deployment: Taking into account the geological variability of each flooded work area along the main line, a composite monitoring section is set up every 100m. Reinforced concrete settlement observation piles are symmetrically embedded in the center of the roadbed, on both sides of the shoulder, and on the top of the counterweight retaining wall at the toe of the slope; time domain reflectance (TDR) moisture sensors and fiber optic displacement sensors are targeted and embedded at depths of 1.0m and 2.0m inside the slope.

[0091] Dynamic feedback control: Before and during the rainy season: Arrange dedicated personnel to regularly read settlement and displacement data, and increase the frequency of inspections during key stages of rising and receding water levels.

[0092] Data indicator response: If the daily deformation of the slope toe settlement displacement pile exceeds 2mm, or if the moisture sensor shows the formation of locally saturated water pockets, it indicates poor local drainage. An emergency plan should be activated immediately: Use a small drilling rig to drill oblique holes into the area and insert Φ50mm perforated pipes as temporary forced drainage holes. Simultaneously, urgently stack bags of sand and gravel outside the counterweight retaining wall for local reinforcement to prevent further deformation.

[0093] Comprehensive post-rainy season check-up: Before construction during the dry season, a comprehensive falling weight deflectometer (FWD) test was conducted on the top deflection of the subgrade and settlement displacement convergence analysis was performed. Continuous observation data verified that the proposed solution can reduce the settlement of high embankment slopes by more than 45% compared to traditional methods, with no gullies, hollowing, or longitudinal cracks appearing on the slopes, and a vegetation cover rate of over 95%.

[0094] This invention is mainly applicable to the following engineering scenarios:

[0095] 1. High embankment roadbeds in the tropical monsoon climate zone of Southeast Asia: such as road and railway roadbed projects in the Mekong River Basin, which are particularly suitable for heavily flooded areas where the flood season lasts for more than 3 months and the water level rises by more than 5m.

[0096] 2. Roadbeds along rivers and lakes in rainy areas of southern China: For example, high embankment roadbeds in the Pearl River Basin and the middle and lower reaches of the Yangtze River in my country, parameters can be adjusted appropriately according to local climate and geological conditions.

[0097] 3. Slope protection for water conservancy projects: protection of the upstream and downstream slopes of reservoirs and dams, especially slope protection in areas of fluctuating water levels.

[0098] 4. Supporting projects for farmland water conservancy: slope protection for irrigation canals and field roads, taking into account both protective functions and ecological landscape effects.

[0099] Seasonal construction safeguards:

[0100] 1. Key points for construction during the dry season

[0101] The construction sequence should be rationally arranged, prioritizing the completion of foundation treatment, embankment filling, and counterweight revetment construction to ensure a complete protective system is formed before the rainy season. Strict moisture content must be controlled during soil filling; if the moisture content exceeds the optimum moisture content by 2%, it should be turned over and sun-dried; if it is below the optimum moisture content, it should be moistened with water. Vegetation construction is best carried out at the end of the dry season, when the temperature is suitable and rainfall is sufficient, which is conducive to seed germination and seedling growth.

[0102] 2. Key points for construction during the rainy season

[0103] Complete the construction of all drainage systems before the rainy season, dredging the intercepting ditches at the top of the slope, the drainage ditches at the toe of the slope, and the transverse blind ditches to ensure smooth drainage. Stockpile sufficient rainproof materials, such as plastic sheeting, sandbags, and water pumps, to cover and protect the top surfaces of constructed slopes and embankments. Stop earthwork filling and slope construction during rainy days; promptly drain surface water after rain and resume work only when the soil moisture content is suitable. Strengthen slope inspections, especially after heavy rains and during the receding water period, focusing on checking for scouring at the toe of the slope and cracks in the slope; address any potential hazards promptly.

[0104] The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. The above embodiments only illustrate several implementations of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. An ecological slope protection structure, characterized in that, include: Main body of the roadbed; The foundation bearing capacity and counterweight base course includes a seepage-proof isolation layer, an inner-edged sandwich embankment, and a counterweight retaining wall. The seepage-proof isolation layer is located at the bottom of the main roadbed and in the inner-edged areas of both sides of the slope. The seepage-proof isolation layer includes a non-expansive soil waterproof isolation layer on the surface of the base and a non-expansive clay inner-edged structure in the inner-edged areas of both sides of the roadbed slope. The inner-edged sandwich embankment adopts an inner-edged sandwich structure. The counterweight retaining wall is constructed at the toe of both sides of the roadbed slope, and the filling height of the counterweight retaining wall is not less than half of the total filling height of the roadbed and is higher than the local periodic highest flood level. A gradient permeable drainage layer is fully laid on the slope outside the seepage-proof isolation layer. The gradient permeable drainage layer includes a reverse filter geotextile and a gravel soil structure layer located outside the reverse filter geotextile. A longitudinal drainage pipe is buried at the bottom of the gravel soil structure layer at the junction with the counterpressure retaining wall. An ecological vegetation soil stabilization layer is provided on the outside of the gradient permeable drainage layer. The ecological vegetation soil stabilization layer includes a porous permeable skeleton fixed on the gravel soil structure layer. The porous permeable skeleton is filled with ecological planting soil and planted with vegetation. The drainage system includes a slope toe drainage ditch and a slope rapid flow channel.

2. The ecological slope protection structure according to claim 1, characterized in that, The inner-edged sandwich embankment section is filled with waterproof and seepage-resistant non-expansion clay as the inner edging within a horizontal width of 1.5m to 2.0m from the slope line. The interior of the section is filled with weakly expansive soil or ordinary soil. The CBR value of the non-expansion clay is not less than 4%, and the compaction degree is not less than 95%.

3. A construction method for an ecological slope protection structure according to claim 1 or 2, characterized in that, Includes the following steps: Step S1: Clear the original ground surface and then replace it with permeable replacement material to complete the replacement of the base bearing capacity. Step S2: Fill the base surface with non-expansion clay or impermeable gravel soil as an impermeable isolation layer, and use the inner edge sandwich process to fill and compact the core layer of the embankment in layers. Step S3: Extra-wide filling is carried out on each side of the embankment. After filling to the top, mechanical slope cutting and trimming are carried out to control the slope ratio to be no steeper than the predetermined value. At the same time, the cleared soil is used to spread and compact the counterweight retaining wall in layers on both sides of the slope toe. Step S4: Lay the reverse filter geotextile on the slope, then spread the gravel soil structure layer in layers on its surface, and pre-embed longitudinal perforated corrugated pipes in the transverse drainage blind ditch inside the slope toe counterweight protection road to form a gradient infiltration drainage layer. Step S5: Install a porous permeable framework on the gradient infiltration drainage layer, fill the framework with planting soil and spray mixed vegetation grass seeds or transplanted turf to form a surface ecological vegetation retention layer. Step S6: Regularly monitor the embankment center, shoulder, and counterweight retaining wall, and reinforce and inspect them based on feedback.

4. The construction method according to claim 3, characterized in that, In step S2, the non-expansive clay used in the inner-edge sandwich process is non-expansive clay or weakly expansive clay with a CBR value of not less than 4%; for soil materials with strong expansibility, 5% to 8% lime is added for improvement.

5. The construction method according to claim 3, characterized in that, The counter-pressure protection road in step S3 adopts a stepped structure, with each step being 2m to 3m high and 2m to 3m wide, and the slope ratio not steeper than 1:1.5; the surface of the protection road is provided with an outward transverse slope of 2% to 3%, and a drainage ditch is provided at the toe of the slope.

6. The construction method according to claim 3, characterized in that, In step S4, a transverse drainage blind ditch is set up every 3m to 5m along the slope height. The transverse drainage blind ditch is filled with gravel and wrapped with reverse filter geotextile. The slope of the transverse drainage blind ditch is not less than 2%, and the outlet extends into the drainage ditch at the toe of the slope.

7. The construction method according to claim 3, characterized in that, The mixed vegetation grass species in step S5 include herbaceous plants and shrubs that are inter-sown. The planting density of the herbaceous plants is 15~20g / m², and the planting density of the shrubs is 1~2 plants / m², or the turf can be directly transplanted from the field and laid on top.

8. The construction method according to claim 3, characterized in that, Step S6 includes: symmetrically burying settlement observation piles and three-dimensional displacement markers in the center of the embankment, the shoulder and the counterweight retaining wall; regularly monitoring settlement deformation and slope moisture content before and after the rainy season, during the rising and receding water stages; dynamically reinforcing seepage points with grouting or adding drainage holes based on data feedback; and conducting roadbed top deflection detection and settlement displacement convergence analysis after the rainy season.

9. The construction method according to claim 3, characterized in that, The gravel soil structure layer in the gradient permeability drainage layer has a thickness of 200mm~400mm. In its filler gradation, the mass percentage of gravel with a particle size of 5mm~40mm is 55%~65%, and the remainder is medium and coarse sand. The permeability coefficient is controlled at 1×10⁻²~1×10⁻³ cm / s.

10. The construction method according to claim 3, characterized in that, The porous permeable framework in the surface ecological vegetation stagnant layer is a sand-free porous permeable concrete hexagonal grid or stacked ecological bags. The porosity of the sand-free porous permeable concrete hexagonal grid is controlled at 20%~30%, and the compressive strength is not less than 15MPa. The ecological vegetation includes mixed herbaceous plants and shrubs. The herbaceous plants are selected from at least one of Bermuda grass, Bahia grass, and lemongrass. The shrubs are selected from at least one of oleander, Amorpha fruticosa, Ligustrum lucidum, and Magnolia multiflora.

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