Ecological protection method for road cutting slope in loess plateau area and application

Abstract

The invention relates to a loess plateau area highway cut slope ecological protection method and application, and the method comprises the following steps: by using the upright characteristic of loess, according to the excavation requirement of a highway slope, preferably adopting a wide-platform steep slope design, arranging a concrete intercepting ditch outside the top of the topmost slope, and spraying a waterproof freeze-thaw resistant material layer on the flat slope surface; a transverse rectangular drainage ditch is arranged on the wide platform, a folding retaining wall is arranged on the inner side of the drainage ditch, a water storage assembly is arranged in an inner cavity of the folding retaining wall, and a water storage retaining wall is arranged on the outer side of the drainage ditch. According to the slope protection system, the slope shallow collapse risk can be reduced by improving the anti-freeze-thaw peeling and shallow collapse protection capacity of the slope, meanwhile, the secondary water damage disaster risk is reduced by adopting a plurality of drainage systems, and the water and soil conservation efficiency is improved under the cooperative use of the folding retaining wall, the water storage retaining wall and the slope protection plants.

Description

Technical Field

[0001] The present application relates to the technical fields of ecological protection and restoration of highway projects and prevention of soil and water loss, and specifically to a method and application for ecological protection of highway cutting slopes in the Loess Plateau. Background Art

[0002] The excavation and protection of highway cutting slopes in the Loess Plateau region is a key project in highway construction. Post-excavation slope protection is an important measure to ensure road safety, stability, and ecological environmental protection. Currently, the following protective measures are primarily adopted after excavation of highway cutting slopes in the Loess Plateau region: Masonry protection, which involves laying stone or concrete on the slope surface to protect the slope and prevent erosion. This method has high construction costs, blocks ecological cycles, creates poor landscape coordination, and significantly impacts the ecological environment; and skeleton plant protection, which utilizes a concrete skeleton combined with grass planting within the skeleton. The concrete skeleton stabilizes the slope, while the roots of plants such as grass planted within the skeleton stabilize the soil, reducing soil erosion. While this method offers certain ecological benefits, the use of green bags within the skeleton structure is poorly adapted to steep slopes (>1:0.75). The bond between the bags and the concrete skeleton is insufficient to withstand the combined effects of gravity, rainwater erosion, and freeze-thaw cycles, which can easily lead to local collapse or overall slippage, making it difficult for vegetation to grow stably. Over time, the bags age and decompose, significantly exacerbating problems such as slope collapse and soil erosion. Geogrid reinforcement uses geotechnical materials to enhance the stability of slope soil. This technology is simple to construct, but its long-term effectiveness is affected by the aging of geotechnical materials, with a five-year strength reduction rate of 30%-50%, posing a long-term reliability risk. Spray seeding involves spraying soil containing grass seeds and fertilizer onto the slope surface to promote rapid vegetation growth. This method contributes to ecological restoration, but when applied to vertical loess slopes, there are technical bottlenecks such as insufficient adhesion (28-day peel strength <0.15MPa) and a substrate shedding rate >35% under freeze-thaw cycles. Concrete panel slope protection uses a prefabricated component assembly protection system and installs prefabricated concrete panels on the slope surface. Although it has excellent erosion resistance, its permeability approaches zero, exacerbating the concentration of slope runoff and inducing gully erosion in the surrounding area. At the same time, it lacks ecological benefits and has a negative impact on the environmental aesthetics.

[0003] At present, the surface of the road cutting slopes in the Loess Plateau region is prone to freeze-thaw peeling. The slopes are easily scaly after being affected by seasonal freeze-thaw, with an annual erosion thickness of 2-5 cm, which can easily induce shallow landslides and affect the overall stability of the slopes. The drainage settings of the slopes are unreasonable, and the lower slopes are easily damaged by water. The current drainage ditch settings have obvious deficiencies. The slope peelings can easily enter and accumulate in the intercepting ditch, but they cannot be discovered and cleaned in time during daily maintenance. As a result, under heavy rain conditions, the water from the upper slope directly rushes to the lower slope, which will develop large-scale water erosion gullies and form gullies with a depth of more than 50 cm. In severe cases, the lower slope will be washed away and collapsed. In addition, the problem of soil erosion on exposed slopes is prominent. In the absence of vegetation protection, rainfall falls directly on the slopes, directly impacting the surface through raindrops, destroying the soil aggregate structure and causing the dispersion of surface soil particles. Rainwater then forms concentrated runoff on the slopes, washing away the loose topsoil and stripping off the surface soil, leading to serious soil erosion. Finally, ecological restoration of steep slopes and platforms is difficult. Due to the steep slope, the natural settlement rate of vegetation on steep slopes is less than 5%, making it difficult for vegetation to attach and grow. The survival rate of artificial greening is poor, making slope ecological restoration and landscape improvement a prominent problem.

[0004] In response to this situation, there is an urgent need to develop an ecological protection system that balances engineering stability, drainage reliability, and ecological sustainability. Furthermore, it is necessary to propose an ecological protection method and application for highway cutting slopes in the Loess Plateau. This method has the advantages of improving highway slope stability, reducing soil erosion, preventing slope damage, and achieving low project costs and good ecological effects. Summary of the Invention

[0005] In response to the above technical problems, the present application provides an ecological protection method and application for highway cutting slopes in the Loess Plateau. The method can effectively prevent and control soil erosion (surface erosion, gully erosion) and large-scale water damage on highway cutting slopes in the Loess Plateau; it can solve the problem of large-scale natural peeling of shallow loess under repeated freezing and thawing under exposed slope conditions, blocking platform drainage ditches, and then inducing secondary disasters such as landslides of the next level of slopes and large-scale water damage; it can achieve platform ecological restoration, improve highway landscape effects, and be conducive to the formation and development of slope crusts, thereby comprehensively improving the ecological benefits of highway slopes in the Loess Plateau.

[0006] Specifically, the present application provides an ecological protection system for the side slopes of highway cuttings in the Loess Plateau region, which is excavated in stages from top to bottom to form multiple wide platforms 2 on the slope surface. A horizontal concrete intercepting ditch 1 is set at the top of the slope, and a longitudinal rapids trough 4 is set from the top to the bottom of the slope. The concrete intercepting ditch 1 is connected to the rapids trough 4, and the surface of the slope is sprayed with an anti-freeze-thaw material layer 3. A drainage ditch 11 is excavated on each wide platform 2, and the drainage ditch 11 is connected to the rapids trough 4. A folding retaining wall 6 is set on the inner side of the drainage ditch 11 close to the slope surface, and a water storage component 7 is set in the inner cavity of the folding retaining wall 6. A water storage retaining wall 8 is set on the outer side of the drainage ditch 11 away from the slope surface, and a planting hole 9 is excavated on the outside of the water storage retaining wall 8. The tops of the folding retaining wall 6 and the planting holes 9 are planted with slope protection plants 10.

[0007] Furthermore, the water storage assembly 7 includes a water supply rod 71 buried inside the folding retaining wall 6, the outer half of the water supply rod 71 is filled with a sand and gravel filling layer 72, and the outer half of the water supply rod 71 is filled with a nutrient soil layer 73. The top of the water supply rod 71 is fixedly connected to a filter screen, and the inner cavity of the water supply rod 71 is fixedly connected to a water-absorbing cotton swab 75. The water-absorbing cotton swab 75 penetrates the nutrient soil layer 73 area above the filter screen. The water supply rod 71 consists of an upper and lower cylindrical structure. The upper and lower cylindrical structures are threaded together, and the middle is only connected by the water-absorbing cotton swab 75. The absorbent cotton swab 75 is connected to the bottom of the inner cavity of the water supply rod 71. Meshes are evenly arranged around the upper cylindrical barrel wall of the water supply rod 71, and meshes are only provided near the middle threaded connection area on the lower cylindrical barrel wall. The upper cylindrical part of the water supply rod 71 is filled with water-retaining material 74. Through the coordinated use of the absorbent cotton swab 75, the barrel wall mesh and the water-retaining material 74, excess water can be accumulated in the lower half of the barrel wall during periods of abundant rain. In periods of drought, the water stored in the lower half of the inner cavity of the water supply rod 71 can be absorbed into the soil through the absorbent cotton swab 75 to meet the water replenishment needs of the plant roots.

[0008] Furthermore, the bottom of the folding retaining wall 6 is buried below the horizontal plane of the wide platform 2, the bottom surface of the folding retaining wall 6 is inclined inwardly toward the slope and buried in the slope to stabilize the slope, and the top surface of the folding retaining wall 6 is inclined inwardly toward the slope to block rainwater; gravel is filled between the folding retaining wall and the slope surface; an overflow pipe 12 is buried at the bottom of the folding retaining wall 6, and the end of the overflow pipe 12 away from the folding retaining wall 6 is connected to the drainage ditch 11.

[0009] Furthermore, the water storage retaining wall 8 is an internal hollow retaining wall buried below the horizontal plane of the wide platform 2, made of concrete or metal, which blocks the water flow on the slope and collects it into the drainage ditch. The water storage retaining wall 8 has irrigation holes or pipes on the side facing the slope protection plants 10, and the top of the water storage retaining wall 8 has a sealing cover, which is provided with a hole for connecting to a water truck.

[0010] Furthermore, the rapid trough 4 is constructed by mortar-laid concrete, cast-in-place concrete or factory prefabrication. A stone barrier 5 for slowing down the water flow is set every 5-10m in the rapid trough. The stone barrier 5 should be 5-7cm higher than the bottom of the rapid trough and 0.5-1m long, which plays the role of water flow energy dissipation.

[0011] Furthermore, a diversion longitudinal slope is set between the foot of the upper slope and the drainage ditch 11 of the wide platform, with a slope of 2%-5%. The diversion longitudinal slope is inclined from the foot of the slope toward the drainage ditch 11 to ensure that the water collected on the slope quickly enters the drainage ditch.

[0012] This application also provides an ecological protection method for any of the above protection systems, comprising the following steps:

[0013] (1) It is suitable for the construction of slopes with a slope ratio of 1:0.3-1:0.5, and is constructed by graded excavation from top to bottom, forming multiple wide platforms 2 on the slope surface, with the width of each platform being greater than 2m;

[0014] (2) A concrete intercepting ditch 1 is excavated horizontally at the top of the slope, and a longitudinal rapids trough 4 is excavated from the top to the bottom of the slope. A drainage ditch 11 is excavated on each wide platform. The inner side of the drainage ditch 11 is excavated close to the slope surface, and a row of rectangular folding retaining walls 6 are buried. The folding retaining walls are installed in an inclined manner, with the lower bottom surface buried in the slope surface, and the top surface of the folding retaining wall 6 is installed inclined toward the slope. The folding retaining wall is preferably a foldable rectangular retaining wall of metal gabions, which is convenient for on-site installation. A water storage retaining wall is excavated outside the drainage ditch 11, and the height of the water storage retaining wall is lower than that of the folding retaining wall.

[0015] (3) Spraying anti-freeze-thaw materials on the slope surface with a spraying thickness of about 1-3 cm;

[0016] (4) The upper surface of the wide platform is covered with reinforced soil, preferably a mixture of alkalized wheat straw reinforced soil and quicklime, with a thickness of 1-3 cm;

[0017] (5) artificially sowing local suitable grass species in the nutrient soil layer of the folding retaining wall, preferably one or more of wheatgrass, Achnatherum splendens, tall fescue, ryegrass, bluegrass or Sudan grass;

[0018] (6) excavating a planting hole 9, wherein the nutrient soil in the planting hole is the same as the nutrient soil in step (5), and is prepared by engineering clearing loess, humus, water retaining agent, organic fertilizer and chemical fertilizer in a weight ratio of 5:3:0.5:1:1; the water retaining agent is a mixture of starch grafted acrylate copolymer cross-linked product and bentonite in a weight ratio of 3:0.5; the organic fertilizer is fermented chicken powder granular fertilizer; the chemical fertilizer is nitrogen, phosphorus and potassium 20-20-20 granular fertilizer; the slope protection plant 10 is selected from local native plants, preferably small trees or shrubs, such as one or more of caragana, apricot, peach or locust. After planting, the planting hole is covered with alkalized wheat straw fiber reinforced soil.

[0019] Furthermore, the drainage ditch 11 is made of cast-in-place concrete or prefabricated and assembled, and can be trapezoidal, rectangular or U-shaped. The cross-sectional dimensions of the drainage ditch must be hydraulically calculated based on the catchment area of the upper slope, the maximum rainstorm intensity, the rainstorm recurrence period, the cross-sectional shape and dimensions. It must ensure that the drainage ditch can drain water smoothly at the maximum design flow rate to avoid excessive scouring or siltation problems. The calculation formula is:

[0020] Q=Av Where Q is the design flow rate (m 3 / s), A is the cross-sectional area of water (m 2 ), v is the water velocity (m / s).

[0021] V = (g × Δh) ^ (0.5) / n, where V is the flow velocity (m / s), g is the acceleration due to gravity (m / s 2 ), Δh is the average water depth of the section (m), and n is the Manning roughness coefficient.

[0022] The present application also provides an anti-freeze-thaw material for ecological protection of road cutting slopes in the Loess Plateau region, comprising the following raw materials in parts by weight: 100 parts of loess, 20-30 parts of bentonite powder, 2-3 parts of biopolymer, 10-15 parts of 1-3 cm wheat straw after alkalization treatment, and 10-15 parts of curing material; wherein the biopolymer is a mixture of xanthan gum and guar gum in a ratio of 2:1 by weight; the curing material is a mixture of polypropylene fiber and polyurethane powder in a ratio of 1:1.5 by weight; the specific preparation process of the anti-freeze-thaw material is to first mix the loess, bentonite powder, biopolymer, and alkalized wheat straw, add water according to 10%-15% of the weight of the mixture, add the curing material, heat and dissolve it, and then move it to the slope surface for compaction, with a compaction degree of more than 90%.

[0023] This application also provides any of the above applications in any of the following aspects:

[0024] (1) Application in improving the ability of slopes to resist freeze-thaw spalling;

[0025] (2) Application in improving the protection capability of shallow slope landslide;

[0026] (3) Application in reducing the risk of secondary water damage;

[0027] (4) Application in promoting slope ecological restoration;

[0028] (5) Application in improving the shear strength of slope soil;

[0029] (6) Application in improving highway safety performance.

[0030] Compared with the prior art, the beneficial technical effects of this application are:

[0031] 1. This application significantly improves slope protection against freeze-thaw spalling and shallow landslides. By promptly spraying anti-freeze-thaw materials on the slope surface, a waterproof and freeze-thaw-resistant protective layer is formed. This effectively inhibits spalling of the loess surface on the highway excavation slope caused by freeze-thaw cycles, reducing the risk of shallow slope landslides. The materials used are engineered cleared loess and environmentally friendly biopolymers, achieving both economic efficiency and ecological compatibility.

[0032] 2. Innovative drainage system design reduces the risk of secondary water damage. Through the synergistic effect of the wide platform's transverse drainage ditch and the longitudinal slope drainage (2%-5% slope), a water retaining wall is set up on the outside of the drainage ditch. Combined with the rapids trough outside the slope line and the folding retaining wall of the gravel inside, they jointly block the energy dissipation structure, achieve rapid drainage and kinetic energy reduction of slope runoff, and avoid scouring and collapse caused by drainage ditch blockage. At the same time, the water retaining wall and anti-seepage treatment further enhance the reliability of the drainage system. A multi-level drainage system is adopted, and the connection between the wide platforms at all levels and the rapids trough, the connection between the intercepting ditch and the rapids trough, and the connection between the drainage ditch and the rapids trough are cleverly designed to form a three-dimensional protective structure system on the steep slope platform.

[0033] 3. For the first time, waterproof and anti-freeze-thaw materials for the cutting slopes of highways on the Loess Plateau were developed. The curing materials used were polyurethane and polypropylene fibers, which can effectively improve the high-temperature resistance of waterproof and anti-freeze-thaw materials, especially the viscosity of waterproof and anti-freeze-thaw materials under high-temperature stress. Through observation, we also found that the use of biopolymers as modifiers can significantly enhance the waterproof and crack resistance of the test samples, and the high tear strength will enhance their anti-freeze-thaw ability in winter. Bentonite can further enhance the viscosity of loess, and alkalized wheat straw provides the anti-friction properties of loess. The addition of these two materials to the curing and protective materials for the slopes of highways on the Loess Plateau can further enhance the curing stability of the samples. After years of slope protection monitoring by scientific researchers, it can effectively enhance the shear strength and erosion resistance of the soil, and has great application potential and broad prospects in the field of slope ecological protection.

[0034] 4. Achieve long-term synergy between engineering protection and ecological functions. Through a combination of wheat straw fiber reinforced soil platform treatment (1-3 cm thick), biopolymer reinforced spraying at the slope foot, and concrete intercepting ditches, this design not only ensures the stability of the slope structure but also provides a matrix for plant growth, promotes the transition from artificial restoration to natural succession, and significantly improves the sustainability of the protection system.

[0035] 5. Significantly reduce maintenance costs throughout the entire lifecycle. A waterproof, freeze-thaw-resistant layer reduces the need for surface repairs, folding retaining walls intercept slope sloughing to prevent drainage ditch clogging, and the low-maintenance nature of native plants (such as Caragana korshinskii and Apricot korshinskii) systematically reduces subsequent dredging, replanting, and structural maintenance costs. Overall operation and maintenance costs are reduced by over 30% compared to traditional masonry protection.

[0036] 6. Improve soil and water conservation efficiency at multiple scales. The slope protection layer reduces surface erosion (erosion reduction ≥80%). The complete system of platform drainage ditch-rapid flow trough-folding retaining wall-water storage retaining wall-vegetation system controls the development of gully erosion, improves soil shear strength (root reinforcement effect), and forms a three-level protection system of "slope-platform-ditch". The soil and water loss control efficiency is 2-3 times higher than that of single engineering measures.

[0037] 7. This application proposes for the first time a method for laying out a folding retaining wall. The provision of a nutrient soil layer can provide a planting area for vegetation. At the same time, the provision of a sand and gravel filling layer allows excessive water to seep downwards from the inner cavity of the folding retaining wall, thereby preventing water and soil erosion in the nutrient soil layer. By using absorbent cotton swabs and water-retaining substances in combination, the water stored at the bottom of the inner cavity of the water supply rod can seep upwards during droughts, thereby meeting the water replenishment needs of the plant roots. By setting the folding retaining wall in an inclined manner, the center of gravity of the folding retaining wall is moved backwards, thereby enhancing its supporting stability and being able to withstand more slope collapses. By setting an overflow pipe, excessive water in the inner cavity of the folding retaining wall can be discharged, thereby preventing water from accumulating in the inner cavity of the folding retaining wall.

[0038] 8. In actual use, the intercepting ditch intercepts the water flow on the top of the slope and collects it into the rapids trough for discharge. At the same time, the folding retaining wall and the water storage retaining wall work together to block the excess slope water flow and collect it into the drainage ditch. The drainage ditch is connected to the rapids trough and can also be discharged through the rapids trough. Planting holes are set at the edge of the wide platform, and slope protection plants are planted in the planting holes. Suitable grass seeds are also planted on the folding retaining wall to strengthen the slope strength. With the coordinated use of the folding retaining wall, the foreign objects sliding down from above can be blocked to prevent soil erosion and large-scale landslides and collapses in extreme weather, thereby improving the safety performance of the highway.

[0039] 9. This application has developed a planting nutrient soil suitable for ecological protection of road cutting slopes in the Loess Plateau. It has excellent water retention performance and is used in combination with the topsoil cleared in highway construction in the Loess Plateau, which has better water retention and air permeability. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a main schematic diagram of the ecological protection system of this application.

[0041] Figure 2 It is a side view schematic diagram of the ecological protection system of this application.

[0042] Figure 3 This application is the ecological protection system Figure 2 A partial enlarged view of point A.

[0043] Figure 4 It is a three-dimensional schematic diagram of the rapids trough in the ecological protection system of this application.

[0044] Figure 5 This is a schematic diagram of the anti-freeze-thaw material layer sprayed on the slope of this application.

[0045] Figure 6 This is a graph showing the water absorption rate of the water-retaining composite material sample of the present application.

[0046] Explanation of the accompanying symbols: 1. Concrete intercepting ditch; 2. Wide platform; 3. Anti-freeze-thaw material layer; 4. Rapids trough; 5. Stone barrier; 6. Folding retaining wall; 7. Water storage component; 71. Water supply rod; 72. Sand and gravel filling layer; 73. Nutrient soil layer; 74. Water-retaining material; 75. Absorbent cotton swab; 8. Water storage retaining wall; 9. Planting hole; 10. Slope protection plant; 11. Drainage ditch; 12. Overflow pipe. DETAILED DESCRIPTION

[0047] The following combines all the Figure 1-6 The present application is further described in detail with specific embodiments.

[0048] Example 1

[0049] Combine Figure 1-4 , an ecological protection system for the cutting slope of a highway in the Loess Plateau area, which is excavated in stages from top to bottom, and multiple wide platforms 2 are formed on the slope surface, a horizontal concrete intercepting ditch 1 is set on the top of the slope, and a longitudinal rapids trough 4 is set from the top to the bottom of the slope, the concrete intercepting ditch 1 is connected to the rapids trough 4, and the surface of the slope is sprayed with an anti-freeze-thaw material layer 3, a drainage ditch 11 is excavated on each wide platform 2, the drainage ditch 11 is connected to the rapids trough 4, a folding retaining wall 6 is set on the inner side of the drainage ditch 11 close to the slope surface, the inner cavity of the folding retaining wall 6 is provided with a water storage component 7, and a water storage retaining wall 8 is set on the outer side of the drainage ditch 11 away from the slope surface, and a planting hole 9 is excavated on the outer side of the water storage retaining wall 8, and slope protection plants 10 are planted on the top of the folding retaining wall 6 and the planting hole 9.

[0050] The bottom of the folding retaining wall 6 is buried below the horizontal plane of the wide platform 2. The bottom surface of the folding retaining wall 6 is inclined inwardly to the side slope and buried in the side slope to stabilize the side slope. The top surface of the folding retaining wall 6 is inclined inwardly to the side slope to block rainwater. The gap between the folding retaining wall and the slope is filled with gravel. An overflow pipe 12 is buried at the bottom of the folding retaining wall 6. The end of the overflow pipe 12 away from the folding retaining wall 6 is connected to the drainage ditch 11. The water storage retaining wall 8 is an internal hollow concrete retaining wall buried below the horizontal plane of the wide platform 2, which blocks the slope water flow and collects it to the drainage ditch. In the ditch, the water storage retaining wall 8 has irrigation holes on the side facing the slope protection plants 10. The top of the water storage retaining wall 8 is provided with a sealing cover, and the sealing cover is provided with a hole for connecting to the water truck. The rapid flow trough 4 is constructed by cast-in-place concrete. A stone barrier 5 for slowing down the water flow is set every 10m in the rapid flow trough. The stone barrier 5 should be 5cm higher than the bottom of the rapid flow trough and 0.5m long. A diversion longitudinal slope is set between the foot of the upper slope and the drainage ditch 11 of the wide platform with a slope of 2%. The diversion longitudinal slope is inclined from the foot of the slope to the drainage ditch 11.

[0051] Example 2

[0052] On the basis of Example 1, the water storage component 7 includes a water supply rod 71 buried inside the folding retaining wall 6, the outer half of the water supply rod 71 is filled with a sand and gravel filling layer 72, and the outer half of the water supply rod 71 is filled with a nutrient soil layer 73. The top of the water supply rod 71 is fixedly connected to the filter screen, and the inner cavity of the water supply rod 71 is fixedly connected to a water-absorbing cotton swab 75. The water-absorbing cotton swab 75 penetrates the nutrient soil layer 73 area above the filter screen. The water supply rod 71 consists of an upper and lower cylindrical structure. The upper and lower cylindrical structures are threaded together, and the middle is only connected by the water-absorbing cotton swab 75. 5. The absorbent cotton swab 75 is connected to the bottom of the inner cavity of the water supply rod 71. Meshes are evenly arranged around the upper cylindrical barrel wall of the water supply rod 71, and meshes are only arranged near the middle threaded connection area on the lower cylindrical barrel wall. The upper cylindrical part of the water supply rod 71 is filled with a water-retaining material 74. Through the coordinated use of the absorbent cotton swab 75, the barrel wall mesh and the water-retaining material 74, excess water can be accumulated in the lower half of the barrel wall during periods of abundant rain. During periods of drought, the water stored in the lower half of the inner cavity of the water supply rod 71 can be absorbed into the nutrient soil through the absorbent cotton swab 75 to meet the water replenishment needs of the plant roots.

[0053] Example 3

[0054] An ecological protection method for a protection system comprises the following steps:

[0055] (1) It is suitable for the construction of slopes with a slope ratio of 1:0.3-1:0.5, and is constructed by graded excavation from top to bottom, forming multiple wide platforms 2 on the slope surface, with the width of each platform being greater than 2m;

[0056] (2) A concrete intercepting ditch 1 is excavated horizontally at the top of the slope, and a longitudinal rapids trough 4 is excavated from the top to the bottom of the slope. A drainage ditch 11 is excavated on each wide platform. The inner side of the drainage ditch 11 is excavated close to the slope surface, and a row of rectangular folding retaining walls 6 are buried. The folding retaining walls are installed in an inclined manner, with the lower bottom surface buried in the slope surface, and the top surface of the folding retaining wall 6 is installed inclined toward the slope. The folding retaining wall is preferably a foldable rectangular retaining wall of metal gabions, which is convenient for on-site installation. A water storage retaining wall is excavated outside the drainage ditch 11, and the height of the water storage retaining wall is lower than that of the folding retaining wall.

[0057] (3) Spraying antifreeze-thaw material on the slope surface with a spraying thickness of about 3 cm; the antifreeze-thaw material formula is the following raw materials in parts by weight: 100 parts of loess, 20 parts of bentonite powder, 2 parts of biopolymer, 10 parts of 3cm wheat straw after alkalization treatment, and 10 parts of curing material; the biopolymer is a mixture of xanthan gum and guar gum in a weight ratio of 2:1; the curing material is a mixture of polypropylene fiber and polyurethane powder in a weight ratio of 1:1.5; the specific preparation process of the antifreeze-thaw material is to first mix loess, bentonite powder, biopolymer, and alkalized wheat straw, add water at a ratio of 10% to 15% by weight of the mixture, add the curing material and heat to dissolve it, and then move it to the simulated slope surface as a test sample and compact it according to a compaction degree of 90%.

[0058] (4) The upper surface of the wide platform is covered with a reinforced soil mixture, specifically a mixture of 3% alkalized wheat straw reinforced soil (by weight) and 5% quicklime (by weight) mixed with reinforced soil, mixed with 20% water (by weight), stirred and evenly covered to a thickness of 3 cm;

[0059] (5) Artificially sowing local suitable grass species in the nutrient soil layer of the folding retaining wall: one or more of wheatgrass, Achnatherum splendens, tall fescue, ryegrass, bluegrass or Sudan grass;

[0060] (6) excavating a planting hole 9, wherein the nutrient soil in the planting hole is the same as the nutrient soil in step (5), and is prepared by engineering clearing loess, humus, water retaining agent, organic fertilizer and chemical fertilizer in a weight ratio of 5:3:0.5:1:1; the water retaining agent is a mixture of starch grafted acrylate copolymer cross-linked product and bentonite in a weight ratio of 3:0.5; the organic fertilizer is fermented chicken powder granular fertilizer; the chemical fertilizer is nitrogen, phosphorus and potassium 20-20-20 granular fertilizer; the slope protection plant 10 is selected from local native plants, preferably small trees or shrubs, such as one or more of caragana, apricot, peach or locust. After planting, the planting hole is covered with reinforced soil containing 3% alkalized wheat straw (weight ratio).

[0061] Example 4

[0062] An antifreeze-thaw material for ecological protection of road cutting slopes in the Loess Plateau region comprises the following raw materials, measured in parts by weight: 100 parts of loess, 20-30 parts of bentonite powder, 2-3 parts of biopolymer, 10-15 parts of alkalized wheat straw with a thickness of 1-3 cm, and 10-15 parts of a solidifying material; the biopolymer is a mixture of xanthan gum and guar gum in a ratio of 2:1 by weight; and the solidifying material is a mixture of polypropylene fiber and polyurethane powder in a ratio of 1:1.5 by weight. The specific preparation process of the antifreeze-thaw material comprises the following steps: firstly mixing the loess, bentonite powder, biopolymer, and alkalized wheat straw, adding water in an amount of 10%-15% by weight of the mixture, adding the solidifying material, heating and dissolving the mixture, and then moving the mixture onto the slope surface for compaction, with a compaction degree of over 90%.

[0063] Experiment 1: Curing performance test of antifreeze-thaw material composition

[0064] Experimental Example 1: The anti-freeze-thaw material formula includes the following raw materials in parts by weight: 100 parts of loess, 20 parts of bentonite powder, 2 parts of biopolymer, 10 parts of 3cm wheat straw after alkalization treatment, and 10 parts of curing material; the biopolymer is a mixture of xanthan gum and guar gum in a ratio of 2:1 by weight; the curing material is a mixture of polypropylene fiber and polyurethane powder in a ratio of 1:1.5 by weight; the specific preparation process of the anti-freeze-thaw material is to first mix the loess, bentonite powder, biopolymer, and alkaline-treated wheat straw, add water at a ratio of 10%-15% by weight of the mixture, add the curing material and heat to dissolve it, and then move it to the simulated slope surface as a test sample, and compact it according to a compaction degree of 90%.

[0065] Experimental Example 2: The anti-freeze-thaw material formula includes the following raw materials in parts by weight: 100 parts of loess, 30 parts of bentonite powder, 3 parts of biopolymer, 15 parts of 3cm wheat straw after alkalization treatment, and 15 parts of curing material; the biopolymer is a mixture of xanthan gum and guar gum in a ratio of 2:1 by weight; the curing material is a mixture of polypropylene fiber and polyurethane powder in a ratio of 1:1.5 by weight; the specific preparation process of the anti-freeze-thaw material is to first mix the loess, bentonite powder, biopolymer, and alkaline-treated wheat straw, add water at a ratio of 10%-15% by weight of the mixture, add the curing material, heat and dissolve it, and then move it to the simulated slope surface as a test sample, and compact it according to a compaction degree of 90%.

[0066] Experimental Example 3: The anti-freeze-thaw material formula includes the following raw materials in parts by weight: 100 parts of loess, 20 parts of bentonite powder, 2 parts of biopolymer, 10 parts of 3cm wheat straw after alkalization treatment, and 20 parts of curing material; the biopolymer is a mixture of xanthan gum and guar gum in a ratio of 2:1 by weight; the curing material is a mixture of polypropylene fiber and polyurethane powder in a ratio of 1:1.5 by weight; the specific preparation process of the anti-freeze-thaw material is to first mix the loess, bentonite powder, biopolymer, and alkaline-treated wheat straw, add water at a ratio of 10%-15% by weight of the mixture, add the curing material and heat to dissolve it, and then move it to the simulated slope surface as a test sample, and compact it according to a compaction degree of 90%.

[0067] Comparative Example 1: Other conditions were the same as those in Experimental Example 1, except that the biopolymer only contained xanthan gum.

[0068] Comparative Example 2: Other conditions were the same as those in Experimental Example 1, except that the biopolymer only contained guar gum.

[0069] Comparative Example 3: Other procedures were the same as those in Experimental Example 1, except that the biopolymer was omitted.

[0070] Comparative Example 4: Other aspects are the same as those of Experimental Example 1, except that the curing agent is only polypropylene fiber.

[0071] Comparative Example 5: Other conditions were the same as those in Experimental Example 1, except that the curing agent was only polyurethane powder.

[0072] Comparative Example 6: Other conditions were the same as those in Experimental Example 1, except that the curing agent, crystal polystyrene, and polyurethane powder were mixed in a ratio of 1:1.5.

[0073] Comparative Example 7: Other conditions were the same as those in Experimental Example 1, except that the curing agent polypropylene fiber and polyurethane powder were mixed in a ratio of 1:1.

[0074] Comparative Example 8: Other procedures were the same as those in Experimental Example 1, except that the bentonite powder was omitted.

[0075] Comparative Example 9: Other aspects were the same as those of Experimental Example 1, except that the alkalized wheat straw was omitted.

[0076] Table 1 Properties of test specimens

[0077]

[0078] Experimental results: The selection of polyurethane and polypropylene fiber as curing materials in the waterproof and anti-freeze-thaw materials for the cutting slopes of the Loess Plateau Highway can effectively improve the high temperature resistance of the waterproof and anti-freeze-thaw materials, especially improve the viscosity of the waterproof and anti-freeze-thaw materials under high temperature stress. It can be seen from Experimental Examples 1-2 in Table 1 that the mixed addition of the curing materials polyurethane and polypropylene fiber is better than the single addition of one or two of them. After increasing the proportion of curing materials in Experimental Example 3, the performance of the test piece decreased, and its viscosity and tear strength were significantly lower than those of Experimental Examples 1-2. Through actual measurement ( Figure 5We also found that the combination of biopolymers as modifiers can significantly enhance the waterproof and anti-freeze-thaw properties of waterproof and anti-freeze-thaw materials, as well as their high tear strength and enhanced anti-freeze-thaw ability in winter.

[0079] The curing reaction of polypropylene fiber and polyurethane resin is primarily caused by the coordinated movement of groups on the molecular chain. The polymer and modifier gradually form a gel-like substance. After undergoing the sol-gel process, the resin system gradually generates a cross-linked three-dimensional network structure, resulting in excellent intermolecular stability. Experiments have shown that the xanthan gum and guar gum mixture in Experimental Example 1-2 of this application, in a 2:1 ratio by weight, exhibits a more synergistic and stable curing effect. In performance tests, the mixture exhibits a higher softening point temperature, higher high-temperature viscosity, and higher tear strength and water-residual stability ratios than other comparative examples, indicating its strong resistance to peeling under water damage and its strong ability to stabilize high and steep slopes.

[0080] Bentonite can further enhance the viscosity of loess, while alkalized wheat straw provides anti-friction properties. Adding these two materials to the Loess Plateau highway slope solidification and protection materials further enhances the solidification and stability of the samples. Years of slope protection monitoring by researchers have shown that these materials can effectively enhance the shear strength and erosion resistance of soil, demonstrating their significant potential and promising prospects for application in slope ecological protection.

[0081] Experiment 2: Test results of water retention performance of planting nutrient soil

[0082] Experimental Example 4: Planting nutrient soil was prepared from engineering cleared loess, humus soil, water-retaining agent, organic fertilizer, and chemical fertilizer in a weight ratio of 5:3:0.5:1:1; the water-retaining agent was a mixture of starch grafted acrylate copolymer and bentonite in a weight ratio of 3 parts:0.5; the organic fertilizer was fermented chicken powder granular fertilizer; and the chemical fertilizer was a 20-20-20 nitrogen, phosphorus, and potassium granular fertilizer.

[0083] Comparative Example 10: Other aspects are the same as those of Experimental Example 4, except that the water-retaining agent is only a starch-grafted acrylate copolymer cross-linked product;

[0084] Comparative Example 11: Other aspects are the same as those of Experimental Example 4, except that the water-retaining agent is a mixture of acrylamide-acrylate copolymer cross-linked product and bentonite in a ratio of 3 parts by weight to 0.5;

[0085] Comparative Example 12: Other aspects are the same as those of Experimental Example 4, except that the water-retaining agent starch grafted acrylate copolymer cross-linked product and bentonite are mixed in a ratio of 3 parts by weight to 1 part by weight;

[0086] Comparative Example 13: Other conditions were the same as those in Experimental Example 4, except that the nutrient soil in the planting hole was prepared from engineering surface-cleared loess, humus soil, water-retaining agent, organic fertilizer, and chemical fertilizer in a weight ratio of 5:3:1:1:1.

[0087] Table 2 Water retention performance test of nutrient soil

[0088]

[0089] Experimental results: The effects of different water-retaining agent compositions of the nutrient soil of this application on the soil ventilation and water content on a 1m*1m test plot were tested. Specifically, after 30 days of watering, the soil moisture content (%), soil ventilation (maximum volumetric oxygen content per square meter of substrate, unit m 3 / m 2 ), the results are shown in Table 2. The best water retention was achieved when the nutrient soil in the planting hole was prepared with loess, humus, water-retaining agent, organic fertilizer, and chemical fertilizer in a weight ratio of 5:3:0.5:1:1. Specifically, the water-retaining agent was a starch-grafted acrylate copolymer cross-linked product: bentonite in a 3:0.5 ratio; the organic fertilizer was fermented chicken powder granular fertilizer; and the chemical fertilizer was a 20-20-20 nitrogen, phosphorus, and potassium granular fertilizer. In Experiment 4, the water-retaining performance test value was 67% water content, and the air flow rate was also high. The study found that bentonite, as a binder, can increase the viscosity of the water-retaining agent. The starch-grafted acrylate copolymer cross-linked product mixed with bentonite forms a network with a high cross-linking density, further enhancing its water-holding capacity. Compared with Comparative Example 10, which did not include bentonite, the water-retaining agent exhibited better water retention, although air flow rate decreased. The experiment concluded that the higher the amount of water-retaining agent and bentonite added, the better. When the addition amount was too high, water retention improved, but soil air flow decreased significantly.

[0090] To determine water absorption, accurately weigh 1g of dry absorbent sample at room temperature, place it in a 1L beaker, add 1L of the test liquid, and let it sit. After the composite material is saturated with water and forms a gel, filter it through a 100-mesh sieve to remove free water. Allow the gel to sit on the sieve for 15 minutes, then weigh the absorbent gel. Sample water absorption (g / g) = (mass of absorbent gel - mass of dry sample) / mass of dry sample. Figure 6 As shown in the water absorption rate of the water-retaining composite material samples, the water retention rate of sample 1 (composite material of starch grafted acrylate copolymer cross-linking material: bentonite in a ratio of 3 parts by weight: 0.5) changes the least with the water retention time, that is, as the water retention time increases, the water retention performance of sample 1 becomes better. On the 6th day of the water retention experiment, its water retention rate is still 90%, followed by sample 4 (starch grafted acrylate copolymer cross-linking material: bentonite in a ratio of 3 parts by weight: 1) 81%, sample 2 (starch grafted acrylate copolymer cross-linking material) 72%, and sample 3 (starch grafted acrylate copolymer cross-linking material) 61%. Sample 1 has the best water retention performance, and its water retention rate on the 6th day of the experiment is 2.19 times that of pure water.

[0091] The above is only a preferred embodiment of the present application and does not constitute any form of limitation to the present application. Although the present application has been disclosed as a preferred embodiment as above, it is not intended to limit the present application. Any technician familiar with this profession can use the technical content disclosed above to make some changes or modifications to an equivalent embodiment with equivalent changes without departing from the scope of the technical solution of the present application. However, any simple modifications, equivalent changes and modifications made to the above embodiment based on the technical essence of the present application without departing from the content of the technical solution of the present application are still within the scope of the technical solution of the present application.

Claims

1. An ecological protection system for highway cutting slopes in the Loess Plateau region, wherein the high slopes of the highway cuttings are excavated in stages from top to bottom to form multiple wide platforms (2) on the slope surface, characterized in that: A transverse concrete intercepting ditch (1) is arranged at the top of the slope, and a longitudinal rapid flow trough (4) is arranged along the top of the slope to the bottom of the slope. The concrete intercepting ditch (1) is connected to the rapid flow trough (4). The surface of the slope is sprayed with an anti-freeze-thaw material layer (3). A drainage ditch (11) is excavated on each wide platform (2). The drainage ditch (11) is connected to the rapid flow trough (4). A folding retaining wall (6) is arranged on the inner side of the drainage ditch (11) close to the slope. The inner cavity of the folding retaining wall (6) is provided with a water storage component (7). A water storage retaining wall (8) is arranged on the outer side of the drainage ditch (11) away from the slope. A planting hole (9) is excavated on the outer side of the water storage retaining wall (8). Slope protection plants (10) are planted on the top of the folding retaining wall (6) and the planting hole (9).

2. The Loess Plateau highway cutting slope ecological protection system according to claim 1 is characterized by: The water storage assembly (7) comprises a water supply rod (71) buried inside the folding retaining wall (6); the portion below one-half of the water supply rod (71) is covered with a sand and gravel filling layer (72); and the portion above one-half of the water supply rod (71) is covered with a nutrient soil layer (73).

3. The ecological protection system for highway cutting slopes in the Loess Plateau region according to claim 2 is characterized by: The top of the water supply rod (71) is fixedly connected to a filter screen, the inner cavity of the water supply rod (71) is fixedly connected to a water-absorbing cotton swab (75), and the upper half of the inner cavity of the water supply rod (71) is filled with a water-retaining material (74); the upper part of the water-absorbing cotton swab (75) passes through the outer area of the filter screen, and the lower part is connected to the bottom of the water supply rod (71).

4. The ecological protection system for road cutting slopes in the Loess Plateau region according to claim 3 is characterized by: The bottom of the folding retaining wall (6) is buried below the horizontal plane of the wide platform (2), and the top surface of the folding retaining wall (6) is inclined inwardly toward the slope; the gap between the folding retaining wall and the slope surface is filled with crushed stones; an overflow pipe (12) is buried at the bottom of the folding retaining wall (6), and the end of the overflow pipe (12) away from the folding retaining wall (6) is connected to the drainage ditch (11).

5. The ecological protection system for road cutting slopes in the Loess Plateau region according to claim 4 is characterized by: The water storage retaining wall (8) is an internal hollow retaining wall buried below the horizontal plane of the wide platform (2), which blocks the water flow on the slope and collects it into the drainage ditch. The water storage retaining wall (8) is provided with irrigation holes or pipes on the side facing the slope protection plants (10). The top of the water storage retaining wall (8) is provided with a sealing cover, and the sealing cover is provided with a hole for connecting with a watering truck.

6. The ecological protection system for road cutting slopes in the Loess Plateau region according to claim 5 is characterized by: The rapid flow trough (4) is constructed by mortar-laid concrete, cast-in-place concrete or factory prefabrication. A stone barrier (5) for slowing down the water flow is arranged every 5-10 m in the rapid flow trough. The stone barrier (5) should be 5-7 cm higher than the bottom of the rapid flow trough and be 0.5-1 m long, so as to dissipate the energy of the water flow.

7. The ecological protection system for highway cutting slopes in the Loess Plateau region according to claim 6 is characterized by: A diversion longitudinal slope is set between the foot of the upper slope and the drainage ditch (11) of the wide platform, with a slope rate of 2%-5%. The diversion longitudinal slope is inclined from the foot of the slope to the drainage ditch (11), ensuring that the water collected on the slope quickly enters the drainage ditch.

8. The ecological protection method according to any one of claims 1 to 7, characterized in that: The steps include: (1) It is suitable for the construction of slopes with a slope ratio of 1:0.3-1:0.5, and is constructed by excavating in stages from top to bottom, forming a plurality of wide platforms (2) on the slope surface, with the width of each platform being greater than 2m; (2) A concrete intercepting ditch (1) is excavated horizontally at the top of the slope, and a longitudinal rapids trough (4) is excavated from the top to the bottom of the slope. A drainage ditch (11) is excavated on each wide platform. A foundation is excavated on the inner side of the drainage ditch (11) close to the slope surface, and a row of rectangular folding retaining walls (6) are buried. The folding retaining walls are installed in an inclined manner, with the lower bottom surface buried in the slope surface, and the top surface of the folding retaining wall (6) is installed in an inclined manner toward the slope. The folding retaining wall is preferably a foldable rectangular retaining wall of metal gabions, which is convenient for on-site installation. A water storage retaining wall is excavated outside the drainage ditch (11) and set, and the height of the water storage retaining wall is lower than that of the folding retaining wall. (3) Spraying anti-freeze-thaw materials on the slope surface with a spraying thickness of 1-3 cm; (4) The upper surface of the wide platform is covered with reinforced soil, preferably a mixture of alkalized wheat straw reinforced soil and quicklime, with a thickness of 1-3 cm; (5) artificially sowing local suitable grass species in the nutrient soil layer of the folding retaining wall, preferably one or more of wheatgrass, Achnatherum splendens, tall fescue, ryegrass, bluegrass or Sudan grass; (6) excavating a planting hole (9), wherein the nutrient soil in the planting hole is the same as the nutrient soil in step (5), and is prepared from the engineering surface clearing loess, humus soil, water retaining agent, organic fertilizer and chemical fertilizer. The slope protection plants (10) are selected from local native plants, preferably small trees or shrubs, such as one or more of caragana, apricot, peach or locust. After planting, the planting hole surface is covered with alkalized wheat straw fiber reinforced soil.

9. The method according to claim 8, characterized in that: The antifreeze-thaw material formula includes the following raw materials in parts by weight: 100 parts of loess, 20-30 parts of bentonite powder, 2-3 parts of biopolymer, 10-15 parts of 1-3 cm wheat straw after alkalization treatment, and 10-15 parts of solidification material.

10. Use of any one of claims 1 to 9 in any one of the following aspects: (1) Application in improving the ability of slopes to resist freeze-thaw spalling; (2) Application in improving the protection capability of shallow slope landslide; (3) Application in reducing the risk of secondary water damage; (4) Application in promoting slope ecological restoration; (5) Application in improving the shear strength of slope soil; (6) Application in improving highway safety performance.

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