Novel ecological base material for ecological restoration of river bank side slope as well as preparation method and application of novel ecological base material

Abstract

The invention relates to the technical field of ecological restoration, in particular to a novel ecological base material for ecological restoration of a river bank side slope and a preparation method and application of the novel ecological base material. The novel ecological base material is prepared from the following raw materials: planting soil, basalt fibers, nano silicon dioxide and cement. The preparation method comprises the following steps: taking the planting soil, crushing, air-drying, and sieving with a 2mm screen; and uniformly mixing and stirring the sieved planting soil, basalt fibers, nano silicon dioxide and cement to obtain a solid mixture, adding water into the solid mixture until the water content is 18.5-19.5%, and uniformly stirring to obtain the novel ecological base material. According to the novel ecological base material, the strength of soil can be greatly improved, the toughness of the soil is improved, the cracking resistance of a soil body is enhanced, dependence on cement is reduced, and carbon emission can be reduced; and on the other hand, the base material has a certain gain effect on plant growth, further has a remarkable promotion effect on adjustment of soil properties and hydrological environment, and also has a positive effect on carbon sequestration.

Description

Technical Field

[0001] The present invention relates to the technical field of ecological restoration, and in particular to a novel ecological substrate for river bank slope ecological restoration, and a preparation method and application thereof. Background Art

[0002] Under the condition of heavy rainfall, the river bank slope will cause the river bank to become unstable, causing soil erosion, and may form mudslides, which are seriously destructive and can flow quickly along the river channel, causing great harm to the downstream areas. Therefore, effective protection measures are needed for the river bank slopes. Ecological slope protection is a method of protecting slopes, banks and other terrains by introducing plant coverage and ecological engineering means, while achieving ecological environmental protection and restoration. However, the current river bank slope protection is often based on physical reinforcement measures such as stone masonry, frame grids, and facing walls. These methods have large one-time investments and poor economic benefits. Therefore, it is particularly important to pursue a green ecological substrate that can not only meet the needs of soil reinforcement performance, but also provide a good plant growth environment. Compared with the defects of plant fibers that are easily eroded by rainwater and decayed and degraded in slope protection, the present invention preferably uses basalt fibers with stronger stability as reinforcing materials.

[0003] The use of ecological substrate is a very important part of the design and construction of ecological slope protection. It is also a new model for the ecological restoration of riverbank slopes, a new technology that emphasizes both riverbank slope engineering protection and ecological greening, and an important material basis for plant survival and growth. Different slope protection technologies have different ecological substrate compositions. Spraying ecological substrate technology is to spray a layer of ecological substrate similar to natural soil on the slope surface, which can combine slope reinforcement with slope vegetation restoration. It has been widely used worldwide. The current ecological substrate curing agents, such as cement, lime and other gray materials, although relatively low in cost, have brought significant environmental problems during their production and application. Cement, as a representative of them, is not only one of the main sources of global carbon dioxide emissions, but also due to its low degradability and strong alkalinity, it leads to an imbalance in soil pH, destroys the original ecological environment, and aggravates the risk of soil desertification. In the existing technology, cement is used as a binder to make the soil alkaline, which is not conducive to vegetation growth. Cement will cause the soil to harden and become brittle. Moreover, the stability of the slope will gradually decrease under the long-term influence of natural factors (such as weathering and erosion). Therefore, the research and development of ecological substrates that have the dual functions of ecological environmental protection and slope protection has become a difficulty and focus in the current field of slope protection technology.

[0004] At present, there are some solutions to the above problems. For example, the patent application with publication number CN115819036A discloses a kind of vegetation concrete and its preparation method, which is prepared by mixing coarse aggregate, cementitious material, admixture and water in proportion. The porosity of vegetation concrete can reach about 20% to 30%, which provides a water-permeable and breathable growth space for plants, allowing the plant roots to penetrate the concrete layer and penetrate into the soil below, thereby enhancing the reinforcement effect of the entire vegetation concrete system. However, the addition of cement greatly increases the alkalinity of vegetation concrete, which is extremely unfavorable for the growth of plants suitable for riverbanks, and the use of cement is not only costly, but also quite harmful to the riverbank environment. The solidified substrate of the present invention can replace most of the cement through basalt fiber and nano-silicon dioxide, greatly reducing the impact of cement. The patent application with publication number CN117776644A discloses an improved collapsible loess roadbed filler, filler preparation method and roadbed construction method. By adding basalt fiber and lime to loess and tamping it with a heavy hammer, not only the loose loess is solidified and the strength is improved, but the addition of fiber can also significantly reduce the brittleness of the loess solidified body and improve its residual strength and toughness. However, the chemical reaction formed by the combination of fiber and lime in the soil is weak, and the strength improvement of the loess roadbed is very limited. In the long run, it is not conducive to the reinforcement of the loess foundation and the ecological restoration project of the river bank slope that requires long-term treatment. The solidified substrate obtained by the present invention through nano-silicon dioxide, basalt fiber and cement has a good chemical reaction and a more obvious strength improvement. The patent application with publication number CN118600965A discloses a method for combining basalt fiber and guar gum to reinforce loess. Basalt fiber and guar gum are added to loess soil in a certain proportion, achieving the combined reinforcement effect of the two. It can not only combine the curing advantages of basalt fiber and guar gum, but also avoid the problem of single guar gum blocking the gap and single fiber producing too many seepage channels, thereby greatly improving the overall strength of the solidified soil, greatly reducing the water sensitivity and permeability of the solidified soil, and effectively improving the compressive strength, crack resistance and water stability of loess. However, as an ecological substrate, guar gum has a high degradation rate and may lose its due strength and vegetation effect in the short term, which is obviously unfavorable for riverbank slope ecological restoration projects that require long-term work. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a new ecological substrate for riverbank slope ecological restoration and its preparation method and application. The present invention selects nano-silicon dioxide and basalt fiber as the raw materials of the new ecological substrate, and adds an appropriate amount of cement for improvement. The combination of basalt fiber and nano-silicon dioxide can replace the large-scale use of cement in the traditional substrate, and has low energy consumption and is neutral in the production and use process. Even after adding a small amount of cement, it will not affect the environmental pH value, improve adhesion and reduce the impact on the ecological environment. In the screening of soil adhesives, several requirements must be met: ① It has a certain bonding ability; ② It is harmless to the environment, does not affect plant growth, and uses natural materials as much as possible; ③ It is easy to use; therefore, fiber-reinforced materials can be selected. Basalt fiber is a new type of inorganic environmentally friendly green high-performance fiber material, which is renewable, and the preparation process is relatively simple, which helps to reduce carbon emissions. It usually has a slender fiber structure and can form a fiber mesh structure inside the clay, thereby limiting the development and deformation of cracks. After mixing basalt fiber with soil, the tensile strength, compressive strength and shear strength of the soil can be effectively increased, and the overall strength and stability of the soil can be improved. Nano-silicon dioxide, due to its high activity, can promote cement hydration, improve early compressive and tensile strength, and its excellent filling effect is especially effective for small and medium pores in the soil. The present invention has obtained data through a large number of experiments to prove that the new ecological substrate can greatly improve the strength of the soil, improve the toughness of the soil and enhance the crack resistance of the soil, reduce dependence on cement, and reduce carbon emissions, thereby having a positive effect on carbon fixation; it can not only achieve ecological restoration and environmental protection of river bank slopes, but also has very important practical significance for the sustainability and social benefits of the project.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme:

[0007] A new ecological substrate for ecological restoration of river bank slopes comprises a main material and auxiliary materials, wherein the main material comprises planting soil, and the auxiliary materials comprise basalt fiber, nano-silicon dioxide 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-silicon dioxide 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-silicon dioxide and cement is 100:0.9:1.5:5;

[0009] Preferably, the planting soil is clay;

[0010] Preferably, the basalt fiber is in bundle shape and has a silicon dioxide content of more than 47%, a length of 10 to 20 mm, a basalt fiber monofilament diameter of 7 to 15 μm, a tensile strength of 3000 to 4800 MPa, an elastic modulus of 91 to 110 GPa, and a density of 2.63 to 2.65 g / cm 3 ;

[0011] Preferably, the nano silicon dioxide is in powder form with a particle size 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 river bank slope ecological restoration comprises the following steps:

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

[0015] (2) Weigh basalt fiber, nano-silicon dioxide, and cement according to the proportion, mix them with the planting soil of step (1) and stir them evenly 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 them evenly to obtain a new ecological substrate.

[0016] A river bank slope ecological restoration method specifically comprises 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-silicon dioxide, and cement according to the proportion, mix and stir with the planting soil in step 1 to obtain a solid mixture, put the solid mixture into the mixing tank of the sprayer, add water to the mixing tank until the water content is 18.5% to 19.5%, and stir mechanically 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, spray the material in the sprayer in step 2 onto the slope surface at high pressure, and spray the material to an average thickness of 8-13cm to obtain a soil matrix layer;

[0020] 4. Sprinkle the seeds evenly on the surface of the soil matrix layer at a ratio of 35-45g of plant seeds per square meter, then put the planting soil in step 1 into the mixing tank of the sprayer, add water to the mixing tank until the moisture content is 18.5%-19.5%, and stir mechanically for no less than 7 minutes (stirring speed is 4-8 rpm);

[0021] 5. Set the distance between the nozzle and the slope surface to 1.5-1.8 m, spray the material in the sprayer in step 4 onto the substrate layer at high pressure, with an average spraying thickness of 2-3 cm to obtain a plant seed layer.

[0022] Preferred plant seeds are ryegrass seeds.

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

[0024] 1. The present invention maintains a vegetation substrate formula based on a natural soil system. The nano-silicon dioxide in the formula provides trace elements in the soil, which helps to improve the fertility of the soil, provide sufficient nutrients and a suitable growth environment for plant growth, help the rapid development of plant roots, and improve the efficiency and effect of vegetation restoration. With the combined effect of plants and ecological substrates, the slope's anti-scouring and anti-erosion capabilities are enhanced. The new ecological substrate can utilize the shear load mechanism between the fiber and the soil particles to enhance the mechanical bite force and friction resistance between the matrix; at the same time, its special physical and chemical properties can effectively resist water scouring and wind and wave erosion, and by enhancing the cohesion and anti-erosion ability of the soil, it can maintain good stability in a complex riverbank environment. Experiments have shown that the new ecological substrate is used for slope ecological protection, not only does it help plants grow well, but it also has high strength and strong anti-scouring ability, achieving the effect of 1+1>2.

[0025] 2. The present invention replaces the use of cement in the traditional ecological substrate by adding basalt fiber + nano-silicon dioxide to the vegetation substrate. Under the same curing conditions, 9% cement is required when pure cement is used as a binder. However, the present invention can achieve the same strength by combining 0.9% basalt fiber, 1.5% nano-silicon dioxide and only 5% cement, reducing the amount of cement by 4%. Based on existing research, the inventor of this application selected polymer as a binder. In order to ensure the connection between the ecological substrate and the slope, basalt fiber was selected. The mutual cooperation of basalt fiber and nano-silicon dioxide makes the ecological substrate and the slope have sufficient bonding force, providing a stable environment for the normal growth of plants on the slope. At the same time, adding 0.9% basalt fiber, 1.5% nano-silicon dioxide and 5% cement into 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-silicon dioxide to replace part of the cement, not only the amount of cement is successfully reduced, the energy consumption and environmental pollution caused by cement production are reduced, but also the compressive strength of the substrate is significantly improved.

[0026] 3. The present invention focuses on the anti-cracking performance of the substrate, which makes up for the shortcomings of the previous research on the anti-cracking performance of the substrate. The ecological substrate solidified soil with the addition of basalt fiber + nano-silicon dioxide has stronger anti-cracking performance. When the optimal ratio of the ecological substrate of the present invention is used, no cracks are generated in the ecological substrate solidified soil, and its crack area and crack length are both 0. The results show that the addition of basalt fiber, nano-silicon dioxide and cement has a significant agglomeration effect on the soil. The cement fills the soil voids and forms a firm bond with the soil particles; the basalt fiber effectively controls the expansion direction of the cracks; and the nano-silicon dioxide further strengthens the bonding effect. The synergistic effect between these materials makes the substrate show the characteristics of shear failure and conical staggered cracks when it is destroyed, which significantly improves the anti-cracking performance of the substrate. Although there are existing literatures that use basalt fiber on the shrinkage cracking of clay soil, it is still the first time to combine basalt fiber, nano-silicon dioxide and cement. The present invention gives the optimal ratio of the combination of the three. The riverbank zone is prone to dry-wet cycles, so it is very important to develop a crack-resistant substrate.

[0027] 4. The present invention opens up new ideas for riverbank slope protection. For the first time, a new ecological substrate composed of clay, basalt fiber, nano-silicon dioxide and cement is applied to riverbank slope protection. The compressive strength of the basalt fiber used is better than that of similar materials such as glass fiber, carbon fiber and polypropylene fiber under similar conditions. As the key raw material of the new ecological substrate, basalt fiber has better bonding with nanomaterials, effectively absorbs and disperses stress, effectively resists the risk of clay damage, and greatly improves the strength and stability of the soil.

[0028] 5. The present invention determines the optimal ratio and preparation method of a new ecological substrate prepared by basalt fiber, nano-silicon dioxide and cement composite material. Only by adopting the optimal dosage and preparation method of the present invention, the new ecological substrate prepared by basalt fiber, nano-silicon dioxide and cement can achieve the best effect of soil reinforcement performance. Moreover, the preparation process of the present invention is simple, easy to operate, low in cost, and meets actual production needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a photo of a sample of a novel ecological substrate prepared by the present invention;

[0030] FIG2 is the stress peak value of the new ecological substrate with different dosages in Example 5;

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

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

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

[0034] Figure 6 These are pictures of ryegrass growth in Example 6. The upper picture shows the growth status of ryegrass at 21 days, and the lower picture shows the growth status of ryegrass at 28 days. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Unless otherwise specified, the materials, reagents, etc. used in the following examples can be obtained from commercial sources; the experimental methods in the following examples are conventional methods unless otherwise specified.

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

[0038] The basalt fiber used is in bundle shape and has a silica content of more than 47%. The length is 10-20 mm. The diameter of the basalt fiber monofilament is 7-15 μm. The tensile strength is 3000-4800 MPa, the elastic modulus is 91-110 GPa, and the density is 2.63-2.65 g / cm 3 The nano silicon dioxide used is in powder form, and the particle size is less than 100nm.

[0039] Example 1

[0040] A new type of ecological substrate suitable for ecological restoration of river bank slopes, composed of planting soil, basalt fiber, nano-silicon dioxide and cement, the mass of basalt fiber is 0.3% of the mass of planting soil, the mass of nano-silicon dioxide 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-silicon dioxide, and cement according to the proportion, mix and stir to obtain a solid mixture, then add water to prepare a sample with a moisture content of 18.87%, and stir to obtain a new ecological substrate.

[0042] (2) The substrate obtained in step (1) is loaded 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 times and compacted using a hydraulic jack. After each compaction, static pressure is performed and wait for 2 to 3 minutes to ensure that the soil sample is fully compacted. The compacted cylindrical sample is placed in a standard curing box at a temperature of 25° C. and cured for 48 hours before demolding to obtain a substrate sample, and its unconfined compressive strength is measured.

[0043] The test method is: use the WDW-10E microcomputer-controlled electronic universal testing machine manufactured by Jinan Naier Testing Machine Co., Ltd. to perform an unconfined compression test. Before the test, place the sample to be tested on the load-bearing platform of the testing machine, and control the descent process of the loading end through the microcomputer. When the loading end is relatively far from the sample, set the descent speed to 50mm / min; when it is observed that the loading end is about to contact the sample, adjust the descent speed to 1mm / min. During the whole process, pay attention to the indicated value of the microcomputer control terminal. Once the force sensor changes by 0.001KN, clear the force and deformation readings. Then, set the loading speed to 1mm / min and start the unconfined compression test on the sample.

[0044] (3) The substrate obtained in step (1) is loaded 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 packaged and wrapped with a plastic film, and then placed in a constant temperature and moisturizing curing box with a relative humidity higher than 90% and a temperature maintained at 25°C for 24 hours. The plastic film is removed to obtain the substrate sample, and the shear strength and cracking effect of the substrate sample are respectively measured.

[0045] The cracking effect test method is as follows: through five dry-wet cycles (one dry-wet cycle, drying for 24 hours, the moisture content of the sample is almost 0; 6 hours of moisture absorption, the sample is almost saturated with water), take pictures to observe the cracking situation, and use Image J software to calculate the area and length of the cracks.

[0046] Shear strength test method: Use the HC-UDR-300 unsaturated soil triple direct shear apparatus manufactured by Suzhou Huicai Soil and Water Engineering Technology Co., Ltd. Before the test, place the sample to be tested on the load-bearing platform of the testing machine. During the test, the axial loading rate was set to 1mm / min, the normal stress was set to 100kpa, 200kpa and 300kpa respectively, and the shear rate was 0.8mm / min. At the beginning of the test, when the shear displacement reaches 4mm, if the specimen is damaged and a shear stress peak appears, the test is terminated immediately. If the shear stress peak is not observed at 4mm, continue the test to 6mm and terminate the test at this time. After the test, record the shear stress value corresponding to the shear deformation of 4mm as the shear peak. After the experiment is completed, unload and remove the specimen, and record the test data.

[0047] Example 2

[0048] A new type of ecological substrate suitable for ecological restoration of river bank slopes, composed of planting soil, basalt fiber, nano-silicon dioxide and cement, the mass of basalt fiber is 0.9% of the mass of planting soil, the mass of nano-silicon dioxide is 1.5% of the mass of planting soil, and the mass of cement is 3% of the mass of planting soil.

[0049] A 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 new type of ecological substrate suitable for ecological restoration of river bank slopes, composed of planting soil, basalt fiber, nano-silicon dioxide and cement, the mass of basalt fiber is 0.9% of the mass of planting soil, the mass of nano-silicon dioxide is 2.5% of the mass of planting soil, and the mass of cement is 3% of the mass of planting soil.

[0052] A 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 new type of ecological substrate suitable for ecological restoration of river bank slopes, composed of planting soil, basalt fiber, nano-silicon dioxide and cement, the mass of basalt fiber is 0.9% of the mass of planting soil, the mass of nano-silicon dioxide is 1.5% of the mass of planting soil, and the mass of cement is 5% of the mass of planting soil.

[0055] A 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 a base material.

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

[0059] Comparative Example 2

[0060] Weigh 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 a base material.

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

[0062] Comparative Example 3

[0063] Weigh 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 a base material.

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

[0065] Comparative Example 4

[0066] Weigh 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 a base material.

[0067] The unconfined compressive strength, shear strength and cracking effect of the substrate were tested according to 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 results of the substrate samples in Examples 1-4 and Comparative Examples 1-4 after five dry-wet cycles are shown in Table 3 below:

[0075] Table 3

[0076]

[0077] It can be seen from the experimental results in Table 1 that the unconfined compressive strength of the sample without any material added in Comparative Example 1 is 226KPa; the unconfined compressive strength of the sample with only 3% cement added in Comparative Example 2 is 575.93KPa, an increase of 154.84% compared with Comparative Example 1; the unconfined compressive strength of the sample with only 5% cement added in Comparative Example 3 is 896.54KPa, an increase of 55.67% compared with Comparative Example 2; the unconfined compressive strength of the sample with only 9% cement added in Comparative Example 4 is 1719.41KPa, an increase of 91.78% compared with Comparative Example 3. In Example 1, the unconfined compressive strength of the new ecological substrate sample with 3% cement, 0.3% basalt fiber and 1.5% nano-silicon dioxide was 1186.18 KPa, which was 105.96% higher than that of Comparative Example 2 and 32.31% higher than that of Comparative Example 3. In Example 4, the unconfined compressive strength of the new ecological substrate sample with 5% cement, 0.9% basalt fiber and 1.5% nano-silicon dioxide was 2089.41 KPa, which was 133.05% higher than that of Comparative Example 3 and 21.52% higher than that of Comparative Example 4.

[0078] From the experimental results in Table 3, it can be seen that the crack length of the sample without any material added in Comparative Example 1 after 5 dry-wet cycles is 167.72 cm and the crack area is 10.23 cm 2 In comparative example 2, only 3% cement was added to the sample, and after 5 dry-wet cycles, the crack length was 28.88cm and the crack area was 1.89cm 2 Compared with the comparative example 1, the crack length was reduced by 480.75% and the crack area was reduced by 441.27%. In the comparative example 3, the sample with only 5% cement was added, and the crack length was 16.32cm and the crack area was 1.21cm after 5 dry-wet cycles. 2 Compared with the comparative example 2, the crack length was reduced by 76.96% and the crack area was reduced by 56.2%. In the comparative example 4, the sample with only 9% cement was added, and the crack length was 10.78cm and the crack area was 0.78cm after 5 dry-wet cycles. 2 Compared with the comparative example 3, the crack length was reduced by 51.39% and the crack area was reduced by 55.13%. In Example 1, the new ecological substrate sample with 3% cement, 0.3% basalt fiber and 1.5% nano-silicon dioxide had a crack length of 14.02 cm and a crack area of ​​0.9 cm after 5 dry-wet cycles. 2Compared with comparative example 2, the crack length was reduced by 105.99% and the crack area was reduced by 110%; compared with comparative example 3, the crack length was reduced by 16.41% and the crack area was reduced by 34.44%. In Example 2, the new ecological substrate sample with 3% cement, 0.9% basalt fiber and 1.5% nano-silicon dioxide had a crack length of 8.23 ​​cm and a crack area of ​​0.49 cm after 5 dry-wet 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 new ecological substrate sample with 5% cement, 0.9% basalt fiber and 1.5% nano-silicon dioxide did not produce cracks after 5 dry-wet cycles, and the anti-cracking effect was significant.

[0079] Example 5

[0080] In order to determine the properties of the substrate and its optimal ratio, the present invention selects to add 0%, 3%, 5%, and 9% cement alone for testing; selects cement dosage of 3%, 5%, basalt fiber dosage of 0.3%, 0.6%, 0.9% and nano-silicon dioxide dosage of 1%, 1.5%, 2%, and 2.5% for orthogonal test; in order to avoid the accidental nature of the experiment, the present invention conducts 3 groups of parallel tests for a total of 84 groups of experiments, and performs unconfined compressive strength tests according to the method in Example 1, and the results are shown in Table 4 below. Wherein, the dosage is the percentage of the mass of cement / basalt fiber / nano-silicon dioxide to the mass of dry soil powder.

[0081] Table 4

[0082]

[0083]

[0084] Figure 2 shows the peak stress of the ecological substrate solidified soil with different dosages. It can be seen from the figure that the unconfined compressive strength of the ecological substrate with different dosages is different. With the increase of cement dosage, the peak value of the unconfined compressive strength becomes larger and larger, but when the ecological substrate dosage is 5% cement + 0.9% basalt fiber + 1.5% nano-silicon dioxide, its peak strength is increased by 21.52% compared with 9% cement, indicating that the peak strength of the cement with lower dosage can achieve a higher effect than that of the high dosage cement when it is matched with basalt fiber and nano-silicon dioxide, which is consistent with the research purpose of the present invention. It is not difficult to see from the experimental results that adding a certain proportion of basalt fiber + nano-silicon dioxide to the original cement not only significantly improves the compressive strength and crack resistance of the soil, but also enhances the stability of the slope and reduces the generation of surface cracks. Even compared with high-content cement samples, the new ecological substrate still shows superior performance. This is because nano-silicon dioxide is a silicon material with nano-scale size, which has a high specific surface area and activity. It can fill the micropores and cracks in the cement matrix and improve the density and firmness of the cement matrix. Nano-silicon dioxide can also react chemically with hydration products such as Ca(OH)2 in cement to form gelling substances, further enhancing the mechanical properties of the cement matrix. Basalt fiber can form a three-dimensional grid structure inside the soil, which can effectively increase the cohesion of the soil, thereby improving the overall strength of the soil. The experimental results of the present invention show that the combination of basalt fiber and nano-silicon dioxide can partially replace cement. The ecological substrate has potential advantages in engineering applications, can effectively reduce the amount of cement used, reduce energy consumption and carbon emissions, improve resource utilization, and reduce engineering costs to a certain extent.

[0085] Example 6

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

[0087] In this planting test, 2500g of clay soil from Wuhan City, Hubei Province was weighed and prepared into a solid mixture according to the ratio of untreated soil, 3% cement, 5% cement, 9% cement, 3% cement + 0.3% basalt fiber + 1.5% nano-silicon dioxide, and 5% cement + 0.9% basalt fiber + 1.5% nano-silicon dioxide, and then prepared into a planting substrate with a moisture content of 18.87%, and two sets of parallel samples were set. The prepared planting substrate was placed in a Hollen pot with a specification of 36cm long, 19cm wide and 15.5cm high, and 1000 ryegrass seeds were evenly sprinkled into the Hollen pot in each group, a layer of water was poured, and then a layer of 3-4mm thin soil was covered on the seeds, gently pressed flat, and placed in a sunny environment with a temperature of about 25℃ for ryegrass planting experiments to explore the effects of different amounts of ecological substrates on ryegrass growth.

[0088] In order to ensure the germination rate of ryegrass in the early growth stage, water was poured once in the morning and evening every day to ensure that each group of potted plants was watered with 100 mL of tap water. The growth of ryegrass was observed and recorded every day, and its maximum height, minimum height, average height, number of seeds, germination rate, etc. were measured. When calculating the germination rate of plants, 1 / 3 of the potted plants were divided into areas. In order to avoid experimental errors, each area was counted multiple times to ensure the accuracy of plant growth parameters. The growth of the plants was measured every 7 days after germination, and the entire test process lasted 28 days. See the growth status of ryegrass for details. Figure 3-6 ,Depend on Figure 3-6It can be seen that for the soil treated with ecological substrates, the germination rate distribution has great fluctuations. For 9% cement, the germination rate is lower than that of plain soil and ryegrass potted plants with other ecological substrates. As the cement content increases, the germination rate is lower because the addition of cement may change the structure and texture of the soil, resulting in increased soil density and decreased permeability, which in turn affects the development of the root system and water absorption. On the 28th day, the germination rates of plain soil and 5% cement + 0.9% basalt fiber + 1.5% nano-silicon dioxide planting reached more than 80%, 81.9% and 83.4% respectively, indicating that the ecological substrate with 5% cement + 0.9% basalt fiber + 1.5% nano-silicon dioxide has a germination rate comparable to that of plain soil without adding any nutrients, which can meet the requirements of river bank slope strength and the needs of vegetation growth. The maximum growth height and average growth height of ryegrass were used to evaluate the growth of plants. The maximum growth height of plain soil reached 18.4 cm on the 28th day, and the average height reached 15 cm. The maximum growth height of ryegrass with 9% cement ecological substrate reached 14.7 cm on the 28th day, and the average height reached 12.2 cm. The maximum growth height was 20.11% lower than that of plain soil, and the average height was 18.67% lower than that of plain soil. The maximum growth height of ryegrass planted in 3% cement + 0.3% basalt fiber + 1.5% nano-silicon dioxide ecological substrate reached 19.5 cm on the 28th day, and the average growth height reached 16.2 cm. The maximum growth height of ryegrass planted in 5% cement + 0.9% basalt fiber + 1.5% nano-silicon dioxide ecological substrate reached 19.1 cm, which was 3.8% higher than that of plain soil, and the average height reached 16.3 cm, which was 8.67% higher than that of plain soil, which was not much different from plain soil.

[0089] The experiment shows that the purpose of the present invention can be met when the ecological substrate dosage is 5% cement + 0.9% basalt fiber + 1.5% nano-silicon dioxide, which has a strong improvement on the vegetation performance of the soil. Nano-silicon dioxide provides trace elements in the soil, which helps to improve the fertility of the soil. The addition of nano-silicon dioxide and basalt fiber forms a good water-retaining structure, slowing down the evaporation of water. The leaves and stems of the upper structure can grow better under stable nutrients, and the addition of an appropriate amount of cement promotes the extension of the roots of the lower structure and penetrates the deep structure of the soil. The roots of the lower structure can more effectively absorb water and nutrients in the soil, thereby promoting the comprehensive development of vegetation. The design of this ecological substrate, while maintaining a certain strength, also creates an ideal growth environment for plants, greatly accelerates the process of ecological restoration, and provides strong support for the natural regeneration and sustainable development of damaged ecosystems.

Claims

1. A new ecological substrate for river bank slope ecological restoration, characterized in that: The raw materials for preparing the novel ecological substrate include: planting soil, basalt fiber, nano-silicon dioxide, and cement; Among them, the mass of basalt fiber is 0.3%~0.9% of the mass of planting soil, the mass of nano-silicon dioxide is 1%~2.5% of the mass of planting soil, and the mass of cement is 3%~9% of the mass of planting soil.

2. The novel ecological substrate according to claim 1, characterized in that: The mass ratio of the planting soil, basalt fiber, nano-silicon dioxide and cement is 100:0.9:1.5:

5.

3. The novel ecological substrate according to claim 1, characterized in that: The basalt fiber is a bundled monofilament with a silicon dioxide content exceeding 47%, a length of 10 to 20 mm, a diameter of 7 to 15 μm, a tensile strength of 3000 to 4800 MPa, an elastic modulus of 91 to 110 GPa, and a density of 2.63 to 2.65 g / cm 3 .

4. The novel ecological substrate according to claim 1, characterized in that: The particle size of the nano silicon dioxide is less than 100 nm.

5. The novel ecological substrate according to claim 1, characterized in that: The cement is PO 42.5 grade ordinary Portland cement.

6. A method for preparing the novel ecological substrate according to any one of claims 1 to 5, comprising 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-silicon dioxide, and cement according to the proportion, mix them with the planting soil in step (1) and stir them evenly to obtain a solid mixture, add water to the solid mixture until the moisture content is 18.5% to 19.5%, and stir them evenly to obtain a new ecological substrate.

7. The preparation method according to claim 6, characterized in that: In step (2), water is added to the solid mixture until the water content reaches 18.87%.

8. A method for ecological restoration of river bank slopes using the novel ecological substrate according to any one of claims 1 to 5, comprising 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-silicon dioxide, and cement according to the proportion, mix and stir with the planting soil in step (1) to obtain a solid mixture, put the solid mixture into the mixing tank of the sprayer, add water to the mixing tank until the water content is 18.5% to 19.5%, and stir mechanically for not less than 7 minutes at a stirring speed of 4 to 8 revolutions per minute; 3. Set the distance between the nozzle and the slope surface to 1.5-1.8 m, spray the material in the sprayer in step 2 onto the slope surface at high pressure, with an average spraying thickness of 8-13 cm, to obtain a soil matrix layer; 4. Sprinkle the seeds evenly on the surface of the soil matrix layer at a ratio of 35-45 grams of plant seeds per square meter, then add the planting soil obtained in step 1 into the mixing tank of the sprayer, add water to the mixing tank until the moisture content is 18.5%-19.5%, and stir mechanically for no less than 7 minutes at a stirring speed of 4-8 revolutions / min; 5. Set the distance between the nozzle and the slope surface to 1.5-1.8 m, spray the material in the sprayer described in step 4 onto the substrate layer at high pressure, with an average spraying thickness of 2-3 cm to obtain a plant seed layer.

9. The river bank slope ecological restoration method according to claim 8, characterized in that: The plant seeds are ryegrass seeds.

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