An ecological substrate for ecological restoration of river bank slope and a preparation method and application thereof

Abstract

The present application relates to the technical field of ecological restoration, in particular to a new ecological substrate for ecological restoration of river bank slope and its preparation method and application. The raw materials of the new ecological substrate include planting soil, basalt fiber, nano-silicon dioxide and cement. The preparation method comprises the following steps: taking the planting soil, crushing, air-drying and then passing through a 2mm sieve; mixing and stirring the sieved planting soil, basalt fiber, nano-silicon dioxide and cement to obtain a solid mixture, then adding water to the solid mixture until the water content is 18.5-19.5%, and stirring uniformly to obtain the new ecological substrate. The new ecological substrate can greatly improve the strength of the soil, improve the toughness of the soil and enhance the anti-cracking property of the soil body, reduce the dependence on cement, and reduce carbon emissions. On the other hand, the substrate has a certain gain effect on plant growth, which can significantly promote the adjustment of soil properties and hydrological environment, and also has a positive effect on carbon sequestration.

Description

Technical Field

[0001] This invention relates to the field of ecological restoration technology, specifically to a novel ecological substrate for riverbank slope ecological restoration, its preparation method, and its application. Background Technology

[0002] Riverbank slopes can become unstable under heavy rainfall, leading to soil erosion and potentially debris flows. These flows are highly destructive, capable of rapidly moving along river channels and causing significant damage to downstream areas. Therefore, effective protective measures are essential for riverbank slopes. Ecological slope protection is a method that protects slopes and riverbanks by introducing vegetation cover and ecological engineering techniques, while simultaneously achieving ecological environmental protection and restoration. However, current riverbank slope protection methods primarily rely on physical reinforcement measures such as masonry, framing, and retaining walls. These methods involve large initial investments and have poor economic returns. Therefore, it is crucial to develop a green ecological substrate that can both meet the needs of soil reinforcement and provide a favorable environment for plant growth. Compared to the vulnerability of plant fibers to rainwater erosion and degradation in slope protection, this invention preferentially uses basalt fiber, which offers greater stability, as a reinforcing material.

[0003] The use of ecological substrates is a crucial part of ecological slope protection design and construction, representing a new model for riverbank slope ecological restoration and a new technology that emphasizes both engineering protection and ecological greening. It is also a vital material basis for plant survival and growth. Different slope protection technologies employ different ecological substrate compositions. Hydroseeding ecological substrate technology involves spraying a layer of ecological substrate similar to natural soil onto the slope, combining slope reinforcement with vegetation restoration, and is currently widely used worldwide. While current ecological substrate solidifying agents, such as cement and lime, are relatively inexpensive, their production and application have brought significant environmental problems. Cement, as a prime example, is not only a major source of global carbon dioxide emissions but also, due to its low degradability and strong alkalinity, causes soil pH imbalance, damaging the original ecological environment and exacerbating the risk of desertification. Existing technologies using cement as a binder result in alkaline soil, which is detrimental to vegetation growth. Furthermore, cement hardens the soil, making it brittle, and the stability of slopes often gradually decreases under long-term natural factors (such as weathering and erosion). Therefore, developing ecological substrates that combine ecological environmental protection and slope protection functions has become a key challenge in the field of slope protection technology.

[0004] Currently, some solutions to the aforementioned problems exist. For example, patent application CN115819036A discloses a type of vegetated concrete and its preparation method, which is made by mixing coarse aggregate, cementitious materials, admixtures, and water in a specific ratio. The porosity of the vegetated concrete can reach approximately 20%–30%, providing plants with a permeable and aerated growing space, allowing plant roots to penetrate the concrete layer and reach the underlying soil, thus enhancing the reinforcement effect of the entire vegetated concrete system. However, the addition of cement significantly increases the alkalinity of the vegetated concrete, which is extremely detrimental to the growth of plants suitable for riverbanks. Furthermore, the use of cement is not only costly but also causes considerable harm to the riverbank environment. The solidified substrate of this invention, using basalt fiber and nano-silica, can replace most of the cement, greatly reducing the impact of cement. Patent application CN117776644A discloses an improved filler for collapsible loess roadbeds, a filler preparation method, and a roadbed construction method. By incorporating basalt fiber and lime into the loess and compacting it with a heavy hammer, the loose loess is solidified, increasing its strength. Simultaneously, the addition of fiber significantly reduces the brittleness of the solidified loess, improving its residual strength and toughness. However, the chemical reaction between the fiber and lime in the soil is weak, resulting in limited strength improvement for the loess roadbed. In the long term, this is detrimental to loess foundation reinforcement and riverbank slope ecological restoration projects requiring long-term treatment. In contrast, the solidified substrate obtained by this invention using nano-silica, basalt fiber, and cement exhibits excellent chemical reaction and a more significant strength improvement. Patent application CN118600965A discloses a method for reinforcing loess using a combination of basalt fiber and guar gum. This method involves adding basalt fiber and guar gum to loess soil in specific proportions, achieving a combined reinforcement effect. This approach combines the solidification advantages of both basalt fiber and guar gum while avoiding the problems of guar gum clogging pores and single fiber creating excessive seepage channels. This significantly improves the overall strength of the solidified soil, substantially reduces its water sensitivity and permeability, and effectively enhances the compressive strength, crack resistance, and water stability of the loess. However, as an ecological substrate, guar gum degrades rapidly and may lose its intended strength-enhancing and vegetation-promoting effects in the short term, which is clearly detrimental to long-term riverbank slope ecological restoration projects. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a novel ecological substrate for riverbank slope ecological restoration, its preparation method, and its application. This invention selects nano-silica and basalt fiber as raw materials for the novel ecological substrate, and incorporates an appropriate amount of cement for improvement. The combination of basalt fiber and nano-silica can replace the large-scale use of cement in traditional substrates, and it features low energy consumption and neutrality during production and use. Even with the addition of a small amount of cement, it does not affect the environmental pH value, improving adhesion while reducing the impact on the ecological environment. Several requirements must be met when selecting soil binders: ① possessing a certain bonding capacity; ② being environmentally friendly, not affecting plant growth, and using natural materials whenever possible; ③ being easy to use; therefore, fiber-reinforced materials can be selected. Basalt fiber is a novel inorganic, environmentally friendly, green, high-performance fiber material. It is renewable, and its preparation process is relatively simple, helping to reduce carbon emissions. It typically has a slender fiber structure, which can form a fibrous network structure inside clay, thereby limiting the development and deformation of cracks. Mixing basalt fibers with soil can effectively increase the tensile strength, compressive strength, and shear strength of the soil, improving its overall strength and stability. Nano-silica, due to its high activity, promotes cement hydration, enhances early compressive and tensile strength, and its excellent filling effect is particularly effective for small and medium-sized pores in the soil. Extensive experimental data demonstrate that this novel ecological substrate can significantly improve soil strength, increase soil toughness and crack resistance, reduce reliance on cement, and lower carbon emissions, thus playing a positive role in carbon sequestration. This not only enables ecological restoration and environmental protection of riverbank slopes but also has significant practical implications for engineering sustainability and social benefits.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A novel ecological substrate for riverbank slope ecological restoration includes a main material and auxiliary materials. The main material includes planting soil, and the auxiliary materials include basalt fiber, nano-silica, and cement. The mass of the basalt fiber is 0.3% to 0.9% of the mass of the main material, the mass of the nano-silica is 1% to 2.5% of the mass of the main material, and the mass of the cement is 3% to 9% of the mass of the main material.

[0008] Preferably, the mass ratio of the planting soil, basalt fiber, nano-silica, and cement is 100:0.9:1.5:5;

[0009] Preferably, the planting soil is clay;

[0010] Preferably, the basalt fibers are in bundle form with a silica content exceeding 47%, a length of 10–20 mm, a monofilament diameter of 7–15 μm, a tensile strength of 3000–4800 MPa, an elastic modulus of 91–110 GPa, and a density of 2.63–2.65 g / cm³. 3 ;

[0011] Preferably, the nano-silica is in powder form with a particle size of less than 100 nm;

[0012] Preferably, the cement is PO 42.5 grade ordinary Portland cement.

[0013] A method for preparing the novel ecological substrate for riverbank slope ecological restoration includes the following steps:

[0014] (1) Take the planting soil, crush it, air dry it, and then pass it through a 2mm sieve for later use;

[0015] (2) Weigh basalt fiber, nano silica and cement according to the ratio, mix them with the planting soil in step (1) to obtain a solid mixture, add water to the solid mixture until the moisture content is 18.5% to 19.5% (preferably 18.87%), and stir evenly to obtain a new type of ecological substrate.

[0016] A method for ecological restoration of riverbank slopes includes the following steps:

[0017] 1. Take the planting soil, crush it, air dry it, and then pass it through a 2mm sieve for later use;

[0018] 2. Weigh basalt fiber, nano silica and cement according to the ratio, mix them with the planting soil in step 1 to obtain a solid mixture, put the solid mixture into the mixing tank of the hydroseeder, add water to the mixing tank until the moisture content is 18.5% to 19.5%, and then mechanically stir for no less than 7 minutes (stirring speed is 4-8 rpm).

[0019] 3. Set the distance between the nozzle and the slope surface to 1.5-1.8m when spraying, and spray the material from the hydroseeding machine in step 2 onto the slope surface under high pressure. The average thickness of the hydroseeding is 8-13cm, and a soil matrix layer is obtained.

[0020] 4. Spread the seeds evenly on the surface of the soil substrate layer at a ratio of 35-45g of plant seeds per square meter. Then put the planting soil from step 1 into the mixing tank of the hydroseeder. Add water to the mixing tank until the moisture content is 18.5%-19.5%, and then mechanically mix for no less than 7 minutes (mixing speed is 4-8 revolutions / min).

[0021] 5. Set the distance between the nozzle and the slope surface to 1.5-1.8m when spraying, and spray the material from the hydroseeder in step 4 onto the substrate layer under high pressure. The average thickness of the hydroseeding layer is 2-3cm, thus obtaining the plant seed layer.

[0022] The preferred plant seed is ryegrass seed.

[0023] Compared with existing technologies, the present invention has the following advantages and beneficial effects:

[0024] 1. This invention maintains a vegetation substrate formulation primarily based on a natural soil system. The nano-silica in this formulation provides trace elements from the soil, helping to improve soil fertility, providing sufficient nutrients and a suitable growth environment for plant growth, promoting rapid root development, and improving the efficiency and effectiveness of vegetation restoration. Through the combined action of plants and the ecological substrate, the slope's resistance to erosion and washout is enhanced. The novel ecological substrate, through its fibers, utilizes the shear load mechanism between its fibers and soil particles to increase the mechanical interlocking force and frictional resistance between the substrates. Simultaneously, its unique physicochemical properties effectively resist water erosion and wave erosion, enhancing soil cohesion and erosion resistance to maintain good stability in complex riverbank environments. Experiments have demonstrated that this novel ecological substrate, used for slope ecological protection, not only promotes healthy plant growth but also exhibits high strength and strong erosion resistance, achieving a synergistic effect greater than the sum of its parts.

[0025] 2. This invention replaces the use of cement in traditional ecological substrates by adding basalt fiber and nano-silica to the vegetation substrate. Under the same curing conditions, using pure cement as a binder requires 9% cement content, while this invention achieves the same strength by combining 0.9% basalt fiber, 1.5% nano-silica, and only 5% cement, reducing cement usage by 4%. Based on existing research, the inventors of this application selected a polymer as the binder, and basalt fiber was chosen to ensure the bond between the ecological substrate and the slope. The synergy between basalt fiber and nano-silica provides sufficient adhesion between the ecological substrate and the slope, offering a stable environment for normal plant growth. Meanwhile, adding 0.9% basalt fiber, 1.5% nano silica and 5% cement to the soil can effectively improve its unconfined compressive strength. At this time, the compressive strength of the substrate is increased by 824.52% compared with the plain soil. This shows that by adding basalt fiber and nano silica to replace part of the cement, not only has the amount of cement been successfully reduced, reducing the energy consumption and environmental pollution caused by cement production, but also the compressive strength of the substrate has been significantly improved.

[0026] 3. This invention focuses on the crack resistance of the substrate, making up for the shortcomings of previous studies on the crack resistance of substrates. The ecological substrate solidified soil with added basalt fiber and nano-silica exhibits stronger crack resistance. Using the optimal ratio of the ecological substrate of this invention, no cracks are generated in the ecological substrate solidified soil; both the crack area and crack length are zero. The results show that the incorporation of basalt fiber, nano-silica, and cement has a significant agglomeration effect on the soil. Cement fills the soil voids and forms a strong bond with soil particles; basalt fiber effectively controls the direction of crack propagation; and nano-silica further enhances the bonding effect. The synergistic effect among these materials causes the substrate to exhibit shear failure and conical interlaced cracks upon failure, significantly improving the crack resistance of the substrate. Although existing literature has used basalt fiber for the drying shrinkage cracking of cohesive soils, this is the first time that basalt fiber, nano-silica, and cement have been combined. This invention provides the optimal ratio of these three components. Riverbank zones are prone to wet-dry cycles, therefore, the development of crack-resistant substrates is very important.

[0027] 4. This invention opens up new avenues for riverbank slope protection. For the first time, a novel ecological substrate composed of clay, basalt fiber, nano-silica, and cement is applied to riverbank slope protection. The basalt fiber used exhibits superior compressive strength compared to similar materials such as glass fiber, carbon fiber, and polypropylene fiber. As a key raw material for this novel ecological substrate, basalt fiber demonstrates superior bonding with nanomaterials, effectively absorbing and dispersing stress to resist the risk of clay damage, thus significantly improving the strength and stability of the soil.

[0028] 5. This invention determines the optimal ratio and preparation method for a novel ecological substrate formulated with basalt fiber, nano-silica, and cement composite materials. Only by using the optimal dosage and preparation method of this invention can the novel ecological substrate formulated with basalt fiber, nano-silica, and cement achieve the best soil reinforcement performance. Furthermore, the preparation process of this invention is simple, easy to operate, and low in cost, meeting practical production needs. Attached Figure Description

[0029] Figure 1 Photographs of the novel ecological substrate samples prepared for this invention;

[0030] Figure 2 shows the peak stress of the novel ecological substrate with different doping amounts in Example 5;

[0031] Figure 3 The germination rate of ryegrass in Example 6;

[0032] Figure 4 This represents the maximum growth height of the ryegrass in Example 6;

[0033] Figure 5 The average growth height of the ryegrass in Example 6;

[0034] Figure 6 The images shown are of ryegrass growth in Example 6. The top image shows the growth of ryegrass at 21 days, and the bottom image shows the growth of ryegrass at 28 days. Detailed Implementation

[0035] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Unless otherwise specified, all materials and reagents used in the following examples are commercially available; and all experimental methods used in the following examples are conventional methods unless otherwise specified.

[0037] The planting soil used in the following examples was clay from Wuhan, with an optimum moisture content of 18.87% and a maximum dry density of 1.75 g / cm³ as determined by compaction tests. 3 The clay was crushed, air-dried, and then filtered through a 2mm sieve to obtain dry clay powder with a particle size of less than 2mm. The cement used was PO 42.5 grade ordinary Portland cement.

[0038] The basalt fibers used are in bundle form with a silica content exceeding 47%, a length of 10–20 mm, a monofilament diameter of 7–15 μm, a tensile strength of 3000–4800 MPa, an elastic modulus of 91–110 GPa, and a density of 2.63–2.65 g / cm³. 3 The nano-silica used is in powder form with a particle size of less than 100 nm.

[0039] Example 1

[0040] A novel ecological substrate suitable for ecological restoration of riverbank slopes is composed of planting soil, basalt fiber, nano-silica, and cement. The mass of basalt fiber is 0.3% of the mass of planting soil, the mass of nano-silica is 1.5% of the mass of planting soil, and the mass of cement is 3% of the mass of planting soil.

[0041] (1) Weigh dry soil powder, basalt fiber, nano silica and cement according to the proportion, mix and stir evenly to obtain a solid mixture, then add water to prepare a sample with a moisture content of 18.87%, and stir evenly to obtain a new type of ecological substrate.

[0042] (2) The substrate obtained in step (1) is placed into a sample mold with a height of 76 mm and a diameter of 38 mm to obtain a cylindrical sample. Specifically, the substrate is added to the mold in five batches and compacted using a hydraulic jack. After each compaction, static pressure is applied and the sample is allowed to stand for 2-3 minutes to ensure that the soil sample is fully compacted. The compacted cylindrical sample is then placed in a standard curing chamber at a temperature of 25°C for 48 hours before demolding to obtain the substrate sample. Its unconfined compressive strength is then measured.

[0043] The test method was as follows: An unconfined compressive strength test was conducted using a WDW-10E microcomputer-controlled electronic universal testing machine manufactured by Jinan Naier Testing Machine Co., Ltd. Before the test, the sample to be tested was placed on the support platform of the testing machine, and the loading end was lowered under the control of the microcomputer. When the loading end was relatively far from the sample, the lowering speed was set to 50 mm / min; when the loading end was observed to be about to contact the sample, the lowering speed was adjusted to 1 mm / min. Throughout the process, the readings on the microcomputer control terminal were monitored. Once the force sensor showed a change of 0.001 kN, the force and deformation readings were reset to zero. Then, the loading speed was set to 1 mm / min, and the unconfined compressive strength test was started on the sample.

[0044] (3) The substrate obtained in step (1) is placed into a ring cutter mold with a height of 20 mm and an inner diameter of 61.8 mm. After compaction, the prepared ecological substrate ring cutter sample is wrapped with plastic film and then placed in a constant temperature and humidity curing chamber with a relative humidity of more than 90% and a temperature of 25°C for 24 hours. The plastic film is removed to obtain the substrate sample. The shear strength and cracking effect of the substrate sample are measured respectively.

[0045] Cracking effect test method: The cracking situation was observed by taking pictures after five dry and wet cycles (one dry and wet cycle, drying for 24 hours, the moisture content of the sample is close to 0; absorbing moisture for 6 hours, the sample is close to water saturation), and the area and length of the crack were calculated by ImageJ software.

[0046] Shear strength testing method: An HC-UDR-300 unsaturated soil triple direct shear apparatus manufactured by Suzhou Huicai Civil Engineering Technology Co., Ltd. was used. Before the test, the sample to be tested was placed on the bearing platform of the testing machine. During the test, the axial loading rate was set to 1 mm / min, the normal stress was set to 100 kPa, 200 kPa, and 300 kPa respectively, and the shear rate was 0.8 mm / min. At the beginning of the test, if the sample failed and a shear stress peak appeared when the shear displacement reached 4 mm, the test was immediately terminated. If no shear stress peak was observed at 4 mm, the test was continued to 6 mm and terminated at that point. After the test, the shear stress value corresponding to the shear deformation of 4 mm was recorded as the shear peak value. After the experiment was completed, the sample was unloaded and removed, and the test data were recorded.

[0047] Example 2

[0048] A novel ecological substrate suitable for ecological restoration of riverbank slopes is composed of planting soil, basalt fiber, nano-silica, and cement. The mass of basalt fiber is 0.9% of the mass of planting soil, the mass of nano-silica is 1.5% of the mass of planting soil, and the mass of cement is 3% of the mass of planting soil.

[0049] The novel ecological substrate was prepared according to the same steps as in Example 1, and its unconfined compressive strength and cracking effect were tested.

[0050] Example 3

[0051] A novel ecological substrate suitable for ecological restoration of riverbank slopes is composed of planting soil, basalt fiber, nano-silica, and cement. The mass of basalt fiber is 0.9% of the mass of planting soil, the mass of nano-silica is 2.5% of the mass of planting soil, and the mass of cement is 3% of the mass of planting soil.

[0052] The novel ecological substrate was prepared according to the same steps as in Example 1, and its unconfined compressive strength and cracking effect were tested.

[0053] Example 4

[0054] A novel ecological substrate suitable for ecological restoration of riverbank slopes is composed of planting soil, basalt fiber, nano-silica, and cement. The mass of basalt fiber is 0.9% of the mass of planting soil, the mass of nano-silica is 1.5% of the mass of planting soil, and the mass of cement is 5% of the mass of planting soil.

[0055] The novel ecological substrate was prepared according to the same steps as in Example 1, and its unconfined compressive strength, shear strength and cracking effect were tested.

[0056] Comparative Example 1

[0057] Take dry soil powder, add water to prepare a sample with a moisture content of 18.87%, and stir evenly to obtain the substrate.

[0058] The unconfined compressive strength, shear strength, and cracking effect of the substrate were tested using the same steps as in Example 1.

[0059] Comparative Example 2

[0060] Weigh out dry soil powder and cement (the mass of cement is 3% of the mass of dry soil powder), mix and stir evenly, then add water to prepare a sample with a moisture content of 18.87%, and stir evenly to obtain the substrate.

[0061] The unconfined compressive strength, shear strength, and cracking effect of the substrate were tested using the same steps as in Example 1.

[0062] Comparative Example 3

[0063] Weigh out dry soil powder and cement (the mass of cement is 5% of the mass of dry soil powder), mix and stir evenly, then add water to prepare a sample with a moisture content of 18.87%, and stir evenly to obtain the substrate.

[0064] The unconfined compressive strength, shear strength, and cracking effect of the substrate were tested using the same steps as in Example 1.

[0065] Comparative Example 4

[0066] Weigh out dry soil powder and cement (the mass of cement is 9% of the mass of dry soil powder), mix and stir evenly, then add water to prepare a sample with a moisture content of 18.87%, and stir evenly to obtain the substrate.

[0067] The unconfined compressive strength, shear strength, and cracking effect of the substrate were tested using the same steps as in Example 1.

[0068] The unconfined compressive strength test results of the substrate samples in Examples 1-4 and Comparative Examples 1-4 are shown in Table 1 below:

[0069] Table 1

[0070]

[0071] The shear strength test results of the substrate samples in Examples 1, 4 and Comparative Examples 1-4 are shown in Table 2 below:

[0072] Table 2

[0073]

[0074] The crack area and crack length of the substrate samples in Examples 1-4 and Comparative Examples 1-4 after five wet-dry cycles are shown in Table 3 below:

[0075] Table 3

[0076]

[0077] The experimental results in Table 1 show that: the unconfined compressive strength of the sample without any added materials in Comparative Example 1 is 226 kPa; the unconfined compressive strength of the sample with only 3% cement added in Comparative Example 2 is 575.93 kPa, an increase of 154.84% compared to Comparative Example 1; the unconfined compressive strength of the sample with only 5% cement added in Comparative Example 3 is 896.54 kPa, an increase of 55.67% compared to Comparative Example 2; and the unconfined compressive strength of the sample with only 9% cement added in Comparative Example 4 is 1719.41 kPa, an increase of 91.78% compared to Comparative Example 3. In Example 1, the novel ecological substrate sample containing 3% cement, 0.3% basalt fiber, and 1.5% nano-silica exhibited an unconfined compressive strength of 1186.18 kPa, representing an increase of 105.96% compared to Comparative Example 2 and 32.31% compared to Comparative Example 3. In Example 4, the novel ecological substrate sample containing 5% cement, 0.9% basalt fiber, and 1.5% nano-silica exhibited an unconfined compressive strength of 2089.41 kPa, representing an increase of 133.05% compared to Comparative Example 3 and 21.52% compared to Comparative Example 4.

[0078] As shown in Table 3, the experimental results in Comparative Example 1, where no materials were added, revealed a crack length of 167.72 cm and a crack area of ​​10.23 cm² after five wet-dry cycles. 2 In Comparative Example 2, the sample containing only 3% cement showed a crack length of 28.88 cm and a crack area of ​​1.89 cm² after five wet-dry cycles. 2 Compared to Comparative Example 1, the crack length was reduced by 480.75% and the crack area by 441.27%; in Comparative Example 3, the crack length of the sample containing only 5% cement after 5 wet-dry cycles was 16.32 cm and the crack area was 1.21 cm². 2 Compared to Comparative Example 2, the crack length was reduced by 76.96% and the crack area by 56.2%; in Comparative Example 4, the crack length of the sample containing only 9% cement was 10.78 cm and the crack area was 0.78 cm² after 5 wet-dry cycles. 2 Compared to Comparative Example 3, the crack length was reduced by 51.39% and the crack area was reduced by 55.13%. In Example 1, the novel ecological substrate sample with 3% cement, 0.3% basalt fiber, and 1.5% nano-silica showed a crack length of 14.02 cm and a crack area of ​​0.9 cm² after 5 wet-dry cycles. 2Compared to Comparative Example 2, the crack length was reduced by 105.99% and the crack area by 110%; compared to Comparative Example 3, the crack length was reduced by 16.41% and the crack area by 34.44%. In Example 2, the novel ecological substrate sample with 3% cement, 0.9% basalt fiber, and 1.5% nano-silica showed a crack length of 8.23 ​​cm and a crack area of ​​0.49 cm² after 5 wet-dry cycles. 2 Compared with Comparative Example 3, the crack length was reduced by 98.3% and the crack area was reduced by 146.94%; compared with Comparative Example 4, the crack length was reduced by 30.98% and the crack area was reduced by 59.18%. In Example 4, the novel ecological substrate sample with a content of 5% cement, 0.9% basalt fiber and 1.5% nano silica did not produce cracks after 5 dry and wet cycles, showing a significant crack resistance effect.

[0079] Example 5

[0080] To determine the properties of the substrate and its optimal proportion, this invention selected 0%, 3%, 5%, and 9% cement as the sole additive for testing; orthogonal experiments were conducted using cement dosages of 3% and 5%, basalt fiber dosages of 0.3%, 0.6%, and 0.9%, and nano-silica dosages of 1%, 1.5%, 2%, and 2.5%; to avoid experimental randomness, this invention conducted 3 sets of parallel experiments, totaling 84 sets of experiments, and performed unconfined compressive strength tests according to the method in Example 1. The results are shown in Table 4 below. The dosage is the percentage of the mass of cement / basalt fiber / nano-silica relative to the mass of dry soil powder.

[0081] Table 4

[0082]

[0083]

[0084] Figure 2 shows the peak stress of solidified soil with different cement dosages as a function of dosage. The figure shows that the unconfined compressive strength varies with different dosages of the ecological substrate. As the cement dosage increases, the peak unconfined compressive strength increases. However, when the ecological substrate dosage is 5% cement + 0.9% basalt fiber + 1.5% nano-silica, the peak strength is 21.52% higher than that of 9% cement. This indicates that a lower cement dosage, when combined with basalt fiber and nano-silica, can achieve a higher peak strength than a higher cement dosage, which is consistent with the research objective of this invention. The experimental results clearly show that adding a certain proportion of basalt fiber and nano-silica to the original cement base not only significantly improves the compressive strength and crack resistance of the soil but also enhances slope stability and reduces surface cracks. Even compared to high-content cement samples, the novel eco-friendly substrate still exhibits superior performance. This is because nano-silica, a silicon material with nanoscale dimensions, possesses a high specific surface area and high activity, capable of filling micropores and cracks in the cement matrix, improving its density and strength. Nano-silica can also chemically react with hydration products such as Ca(OH)2 in cement to form cementitious substances, further enhancing the mechanical properties of the cement matrix. Basalt fibers can form a three-dimensional mesh structure within the soil, effectively increasing the soil's cohesion and thus improving its overall strength. The experimental results of this invention demonstrate that the combination of basalt fibers and nano-silica can partially replace cement. This eco-friendly substrate has potential advantages in engineering applications, effectively reducing cement usage, energy consumption and carbon emissions, improving resource utilization, and to some extent reducing engineering costs.

[0085] Example 6

[0086] This embodiment uses ryegrass as a soil-fixing plant to study the vegetation growth performance of different ecological substrates. Ryegrass has strong adaptability and a certain tolerance to various extreme weather conditions. It can grow in various environments and has a stable soil-fixing effect. It grows quickly and has a well-developed root system, which can form dense vegetation cover in a short period of time, providing effective soil protection and soil-fixing effects.

[0087] In this planting experiment, 2500g of clay soil from Wuhan, Hubei Province, was used to prepare solid mixtures in the following proportions: untreated soil, 3% cement, 5% cement, 9% cement, 3% cement + 0.3% basalt fiber + 1.5% nano-silica, and 5% cement + 0.9% basalt fiber + 1.5% nano-silica. These mixtures were then used to prepare planting substrates with a moisture content of 18.87%, and two parallel samples were prepared. The prepared planting substrates were placed in Hollen pots (36cm long, 19cm wide, and 15.5cm high). 1000 ryegrass seeds were evenly scattered into each pot, watered, and then covered with a 3-4mm layer of soil, gently pressed flat, and placed in a sunny environment at approximately 25℃ to investigate the effects of different amounts of ecological substrate on ryegrass growth.

[0088] To ensure a high germination rate in the early stages of ryegrass growth, water was applied twice daily, morning and evening, with each potted plant receiving a consistent 100mL of tap water. The growth of the ryegrass was observed and recorded daily, including maximum height, minimum height, average height, number of seeds, and germination rate. When calculating the germination rate, one-third of the potted plants were divided into sections, and to avoid experimental errors, measurements were taken multiple times for each section to ensure the accuracy of the plant growth parameters. After germination, the plant growth was measured every 7 days, and the entire experiment lasted 28 days. The growth status of the ryegrass is shown in [link to relevant documentation]. Figure 3-6 ,Depend on Figure 3-6It can be seen that the germination rate of soil treated with ecological substrates varies greatly. For 9% cement, the germination rate is lower than that of plain soil and ryegrass potted plants with other ecological substrates. The reason why the germination rate decreases as the cement content increases is that the addition of cement may change the soil structure and texture, leading to increased soil density and decreased permeability, which in turn affects root development and water absorption. On day 28, the germination rate of plain soil and soil treated with 5% cement + 0.9% basalt fiber + 1.5% nano-silica both reached over 80%, specifically 81.9% and 83.4%, respectively. This indicates that the ecological substrate with 5% cement + 0.9% basalt fiber + 1.5% nano-silica, without the addition of any nutrients, has a comparable germination rate to plain soil, which can meet both the strength requirements of the riverbank slope and the needs of vegetation growth. The growth status of ryegrass was evaluated by its maximum and average height. In plain soil, the maximum height reached 18.4 cm and the average height reached 15 cm on day 28. Ryegrass with 9% cement-based ecological substrate reached a maximum height of 14.7 cm and an average height of 12.2 cm on day 28, representing a 20.11% decrease in maximum height and an 18.67% decrease in average height compared to plain soil. Ryegrass planted in a 3% cement + 0.3% basalt fiber + 1.5% nano-silica ecological substrate reached a maximum height of 19.5 cm and an average height of 16.2 cm on day 28. Ryegrass planted in a 5% cement + 0.9% basalt fiber + 1.5% nano-silica ecological substrate reached a maximum height of 19.1 cm, a 3.8% increase compared to plain soil, and an average height of 16.3 cm, an 8.67% increase compared to plain soil, showing little difference from the plain soil results.

[0089] This experiment demonstrates that an ecological substrate composition of 5% cement + 0.9% basalt fiber + 1.5% nano-silica meets the research objectives of this invention, significantly improving soil vegetation performance. Nano-silica provides trace elements to the soil, contributing to increased fertility. The addition of nano-silica and basalt fiber creates a good water-retention structure, slowing down water evaporation. Leaves and stems in the upper structure can grow better under stable nutrient conditions. The appropriate amount of cement promotes root extension in the lower structure, penetrating deeper into the soil. The roots in the lower structure can more effectively absorb water and nutrients from the soil, thus promoting comprehensive vegetation development. This ecological substrate design maintains a certain strength while creating an ideal growth environment for plants, greatly accelerating the ecological restoration process and providing strong support for the natural regeneration and sustainable development of damaged ecosystems.

Claims

1. An ecological substrate for riverbank slope ecological restoration, characterized in that, The raw materials of the novel ecological substrate include: planting soil, basalt fiber, nano-silica, and cement; The basalt fiber accounts for 0.9% of the planting soil mass, the nano-silica mass accounts for 1.5% of the planting soil mass, and the cement mass accounts for 5% of the planting soil mass. The basalt fibers are bundled monofilaments with a silica content exceeding 47%, a length of 10–20 mm, a monofilament diameter of 7–15 μm, a tensile strength of 3000–4800 MPa, an elastic modulus of 91–110 GPa, and a density of 2.63–2.65 g / cm³. 3 The nano-silica has a particle size of less than 100 nm; the cement is PO 42.5 grade ordinary Portland cement; The method for preparing the novel ecological substrate includes the following steps: (1) Take the planting soil, crush it, air dry it, and then pass it through a 2mm sieve for later use; (2) Weigh basalt fiber, nano silica and cement according to the ratio, mix them with the planting soil in step (1) to obtain a solid mixture, add water to the solid mixture until the moisture content is 18.87%, and mix them evenly to obtain a new type of ecological substrate.

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