Ecological sand barrier based on biological induction of calcium carbonate precipitation and construction method thereof

Abstract

The invention discloses an ecological sand barrier based on biological induction of calcium carbonate precipitation and a construction method thereof, and the construction method comprises the following steps: mixing cut plant fibers with sandy soil to obtain a mixture; a bulldozer is used for stacking the mixture into a string-shaped mound, and water is sprayed to the string-shaped mound so that the mound can be formed preliminarily; covering the preliminarily formed chord-shaped mound with a fiber geomembrane, and fixing the fiber geomembrane by using wood nails; eICP slurry or MICP slurry is uniformly sprayed on the outer surface of the fiber geomembrane, and the EICP slurry or the MICP slurry permeates into the string-shaped mound, so that the string-shaped mound is solidified and cemented with the fiber geomembrane to form the ecological sand barrier. Therefore, the purposes of low cost and high benefit of resource utilization and desert control are achieved, and the constructed ecological sand barrier has rigidity and toughness and is high in wind erosion resistance and good in durability.

Description

Technical Field

[0001] The invention relates to the technical field of desertification control, and in particular to an ecological sand barrier based on biologically induced calcium carbonate precipitation and a construction method thereof. Background Art

[0002] Desertification is one of the global ecological and environmental problems, posing a threat to agriculture, ecosystems and human living environments. In order to control desert expansion and restore ecology, many sand fixation technologies have been developed, including clay sand barriers, grass grid sand barriers, chemical sand fixation agents, etc.

[0003] Clay sand barriers and grass grid sand barriers are currently the most common ways to fix sand. Clay sand barriers weaken wind erosion by building clay barriers on the surface of the sand, and form a stable vortex structure inside the sand barrier to accumulate sand. However, this technology relies on a large amount of clay resources, requires long-distance transportation and mechanical handling and accumulation, has high construction costs, low efficiency, is easily eroded, and has a limited service life. Although grass grid sand barriers are low in cost, their durability and wind resistance are limited, and they have a large demand for resources and a short service life.

[0004] In recent years, microbial induced calcium carbonate precipitation (MICP) and enzyme induced calcium carbonate precipitation (EICP) technologies have gradually emerged in desert control due to their environmental protection characteristics and high reinforcement performance. MICP / EICP technology is to induce urea decomposition by microorganisms or enzymes to produce calcium carbonate precipitation, thereby achieving the improvement of soil particle cementation and anti-erosion performance. Studies have shown that MICP / EICP technology can significantly enhance the shear strength and compression strength of soil, but the treated soil may still have a certain degree of brittleness; and if EICP / MICP sand fixation is carried out on the entire area, the cost is high and it is easy to be damaged locally, resulting in poor durability. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies in material handling and construction efficiency in the construction of sand barriers in related technologies, and to achieve the low-cost, high-efficiency goals of resource utilization and desert control. Moreover, the constructed ecological sand barrier has both rigidity and toughness, strong resistance to wind erosion and good durability.

[0006] In order to achieve the above-mentioned object, the present invention proposes in a first aspect a method for constructing an ecological sand barrier based on biologically induced calcium carbonate precipitation, comprising the following steps: Mixing chopped plant fibers with sand to obtain a mixture; Using a bulldozer to pile the mixture into a string-shaped soil pile, and spraying water on the string-shaped soil pile to preliminarily shape the soil pile; Covering the fiber geomembrane on the initially formed string-shaped soil pile, and fixing the fiber geomembrane with wooden nails; The EICP slurry or the MICP slurry is uniformly sprayed on the outer surface of the fiber geomembrane, and the EICP slurry or the MICP slurry penetrates into the string-shaped soil pile, so that the string-shaped soil pile is solidified and bonded with the fiber geomembrane to form an ecological sand barrier.

[0007] According to an embodiment of the present invention, a method for constructing an ecological sand barrier based on biologically induced calcium carbonate precipitation is provided. The method firstly adds plant fiber to sand and mixes it, then piles the sand and the fiber into a string-shaped soil pile with a bulldozer during the advancement process, then sprays a certain amount of water to make the soil pile initially formed, and then lays a fiber geomembrane to cover the string-shaped soil pile, and finally sprays EICP slurry or MICP slurry to reinforce the soil pile to form a fiber-reinforced ecological sand barrier; the calcium carbonate cementing layer formed by EICP / MICP can significantly improve the soil's wind erosion resistance, reduce the wind erosion problem of traditional sand barriers, and the plant fiber can limit the displacement of sand, improve the tensile strength and toughness, and solve the problem of brittle failure of single EICP / MICP technology; that is, calcium carbonate precipitation fills the pores, cements the soil particles to form a stable structure, and the fiber plays a bridging role, further connects the soil particles and calcium carbonate crystals, and improves the toughness of the soil. In addition, the fiber geomembrane further plays a role in wind protection; so that the constructed ecological sand barrier has both rigidity and toughness, strong wind erosion resistance, and good durability. Furthermore, this method uses desert sand and natural fibers to construct ecological sand barriers, reducing dependence on external materials and transportation, improving construction efficiency, reducing costs, and the layout of sand barriers can be flexibly adjusted according to the terrain.

[0008] Optionally, the plant fiber includes at least one of straw fiber, coconut shell fiber and hemp fiber; the length of the chopped plant fiber is 1 cm-15 cm.

[0009] Optionally, the added amount of the plant fiber is 0.2%-0.6% of the mass of the sand.

[0010] Optionally, the plant fibers and the sand are mixed by rotating and stirring.

[0011] Optionally, the string-shaped soil mound is a strip-shaped soil mound, a wave-shaped soil mound or a chessboard-shaped soil mound.

[0012] Optionally, the fiber geomembrane has water-permeable micropores that are permeable to water but impermeable to sand.

[0013] Optionally, the edge of the fiber geomembrane covers at least 10 cm of the bottom of the chord-shaped soil pile, the wooden nails are set at the edge of the fiber geomembrane and arranged at intervals along the length direction of the chord-shaped soil pile, and the distance between two adjacent wooden nails is 50 cm-100 cm.

[0014] Optionally, the EICP slurry is formed by mixing urease and a binder in a volume ratio of 1:1, the concentration of the binder is 0.1mol / L-0.4mol / L, and the urease activity is 5 U / mL-10 U / mL; the MICP slurry is formed by mixing Bacillus pasteurianus bacterial solution and a binder in a volume ratio of 1:1, the concentration of the binder is 0.1mol / L-0.4mol / L, and the activity of the Bacillus pasteurianus bacterial solution is 5 U / mL-10 U / mL.

[0015] Optionally, the application amount of the EICP slurry or the MICP slurry is 1 L-3 L per square meter; the EICP slurry or the MICP slurry is applied by spraying.

[0016] In a second aspect, the present invention provides an ecological sand barrier, which is constructed using the above-mentioned method for constructing an ecological sand barrier based on biologically induced calcium carbonate precipitation. The ecological sand barrier comprises: A string-shaped soil pile, wherein the string-shaped soil pile is mixed with plant fiber and sand and solidified by EICP slurry or MICP slurry; A fiber geomembrane, wherein the fiber geomembrane covers the outer surface of the chord-shaped soil pile and is bonded to the chord-shaped soil pile through the EICP slurry or the MICP slurry; Wooden nails are arranged at the edge of the fiber geomembrane to fix the fiber geomembrane to the sand.

[0017] The ecological sand barrier according to the embodiment of the present invention has both rigidity and toughness, strong resistance to wind erosion and good durability; and can solve the deficiencies in material handling and construction efficiency in constructing sand barriers in related technologies, and achieve the low-cost, high-efficiency goals of resource utilization and desert control.

[0018] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic diagram of the construction process of an ecological sand barrier according to an embodiment of the present invention; Figure 2 is a cross-sectional view of an ecological sand barrier according to an embodiment of the present invention; Figure 3 : are the orientation arrangement and parameters of the ecological sand barrier according to an embodiment of the present invention, wherein (a) strip shape; (b) wave shape; (c) chessboard shape; (d) angle α and amplitude A of the sinusoidal wave strip unit; (e) sand barrier spacing L and sand barrier slope θ; Figure 4 The effects of different fiber lengths, contents and different reinforcement times on the strength of the ecological sand barrier according to the embodiments of the present invention; Figure 5 The effects of different cementing fluid concentrations and different reinforcement times on the wind erosion rate of the ecological sand barrier according to the embodiments of the present invention; Figure 6 is a microscopic structure diagram of an ecological sand barrier according to an embodiment of the present invention; Figure 7 The figure shows the influence of different sand barrier orientations on the wind erosion rate of the ecological sand barrier according to an embodiment of the present invention. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is described below through specific examples. It should be understood that the one or more method steps mentioned in the present invention do not exclude the existence of other method steps before and after the combination step or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to limit the scope of the present invention. The change or adjustment of the relative relationship thereof shall also be regarded as the scope of the present invention without substantially changing the technical content.

[0021] In order to better understand the above technical scheme, the exemplary embodiments of the present invention are described in more detail below. Although exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to enable the scope of the present invention to be fully communicated to those skilled in the art.

[0022] The test materials used in the present invention are all common commercial products and can be purchased in the market.

[0023] The MICP / EICP technology mentioned in the above background technology can significantly enhance the shear strength and compression strength of the soil, but the treated soil may still have a certain degree of brittleness; and if EICP / MICP sand fixation is carried out on the entire area, the cost is high and it is easy to be damaged locally, resulting in poor durability. The present application provides a method for constructing an ecological sand barrier based on biologically induced calcium carbonate precipitation. In this method, Figure 6As shown, when constructing an ecological sand barrier, calcium carbonate precipitation fills the pores and cements the soil particles to form a stable structure. The plant fibers play a bridging role, further connecting the soil particles and calcium carbonate crystals to improve the toughness of the soil. The fiber geomembrane further plays an anti-wind protection role. The calcium carbonate cementing layer formed by the EICP slurry or the MICP slurry significantly improves the wind erosion resistance of the soil in the constructed ecological sand barrier, reduces the wind erosion problem of traditional sand barriers, and uses plant fibers to limit the displacement of sand and soil to improve the tensile strength and toughness of the ecological sand barrier, thereby enhancing the wind erosion resistance and durability of the ecological sand barrier, and making the construction efficient, low-cost and flexible.

[0024] The present invention is described below with reference to specific embodiments. It should be noted that these embodiments are merely illustrative and do not limit the present invention in any way.

[0025] Example 1 Effects of different fiber lengths, contents and different reinforcement times on ecological sand barriers Figure 1 For a schematic diagram of the construction process of the ecological sand barrier proposed in the embodiment of the present invention, please refer to Figure 1 According to a specific embodiment of the present invention, a method for constructing an ecological sand barrier based on biologically induced calcium carbonate precipitation comprises the following steps: S1. Preliminary formation of soil pile The straw fibers are cut to 1-5 cm, 5-10 cm and 10-15 mm, respectively, and the addition ratio of the straw fibers is 0.0%, 0.2%, 0.4% and 0.6% of the mass of the sand, respectively; the straw fibers are evenly added to the sand by means of rotary stirring, and then the sand and the straw fibers are piled into a strip-shaped soil pile by a bulldozer during the propulsion process, followed by spraying a certain amount of water (0.5 L / m²) to make the soil pile initially formed. In this embodiment, the walking route of the bulldozer is strip-shaped. Among them, the rotary stirring method can be to use a double-shaft paddle mixer; two parallel stirring shafts pass through both sides of the stirring tank, and staggered paddles are evenly distributed on the shafts. The two stirring shafts rotate synchronously or in the opposite direction, and the materials are forced to be convectively stirred through the interaction of the paddles, so that the materials can achieve a uniform mixing effect in a short time.

[0026] S2, film laying and fixing Please refer to Figure 2, a water-permeable but sand-impermeable fiber geomembrane roll is laid on top of the initially formed soil pile with a grass-laying machine, and the edge of the membrane covers at least 10 cm from the bottom of the soil pile. The edge of the membrane is fixed with wooden nails of about 20-30 cm, and the wooden nails are spaced 50-100 cm apart along the length of the soil pile. Among them, the fiber geomembrane can be LDPE (low-density polyethylene) as the geomembrane substrate, and the plant fiber is directly pierced into the geomembrane by needle puncture, so that the two are tightly combined to obtain a fiber geomembrane. Specifically, the diameter of the plant fiber is about 0.1-2 mm, the aspect ratio is 50-150, the distribution density of the plant fiber on the surface of the geomembrane is 100-300 roots / square meter, and the depth of penetration into the substrate should be controlled at 50%-80% of the thickness of the substrate. The plant fiber is directly pierced into the LDPE substrate by a needle puncture process. During the needle puncture process, the substrate is softened by heat (the temperature is controlled at 80℃-120℃), so that the fiber is embedded in the substrate and then cooled and solidified to form a physical anchoring structure without the need for additional adhesives.

[0027] S3, reinforcement molding Use spraying equipment to evenly spray the EICP slurry on the surface of the fiber geomembrane. The application amount is controlled at 1 L / m² each time. Spray once a day for 4 consecutive days to build a Figure 3 (a) shows the strip-shaped sand barrier; the spacing L of the strip-shaped sand barrier is 1.5 m, the height h of the strip-shaped sand barrier is 15 cm, and the slope θ is 10°. The EICP slurry used is composed of urease and cementing liquid (urea and calcium chloride), the volume ratio of urease to cementing liquid is 1:1; the concentration of cementing liquid is 0.2 mol / L, and the ratio of urea to calcium chloride in the cementing liquid is 1.5:1; urease is extracted from soybean, and the urease activity is about 5 U / mL.

[0028] The surface strength of the sand slope of the strip sand barrier is tested regularly using a micro-penetrator. Figure 4 As shown in the figure, the more times the reinforcement is applied, the higher the surface strength of the sand is; the addition of fibers can further improve the surface strength of the sand. Therefore, the most cost-effective option is to reinforce the sand three times, that is, spray once a day for three consecutive days, with a fiber content of 0.4%. In addition, the fiber length also affects the reinforcement effect of EICP sand fixation, as shown in the figure. Figure 4 It can be seen that the reinforcement effect of short fibers of 1-5 cm is the best.

[0029] Example 2 Effects of different binder concentrations and different reinforcement times on ecological sand barriers Figure 1 For a schematic diagram of the construction process of the ecological sand barrier proposed in the embodiment of the present invention, please refer to Figure 1 According to a specific embodiment of the present invention, a method for constructing an ecological sand barrier based on biologically induced calcium carbonate precipitation comprises the following steps: S1. Preliminary formation of soil pile The straw fiber is cut to 1-5 cm, and the addition ratio of the straw fiber is 0.4% of the mass of the sand; the straw fiber is evenly added to the sand by means of rotary stirring, and then the sand and the straw fiber are piled into a strip-shaped soil pile by a bulldozer during the propulsion process, and then a certain amount of water (0.5 L / m²) is sprayed to initially form the soil pile. In this embodiment, the walking route of the bulldozer is strip-shaped. Among them, the rotary stirring method can be to use a double-shaft paddle mixer; two parallel stirring shafts pass through both sides of the stirring tank, and staggered blades are evenly distributed on the shafts. The two stirring shafts rotate synchronously or in the opposite direction. Through the interaction of the blades, the material is forced to be convectively stirred, so that the material can achieve a uniform mixing effect in a short time.

[0030] S2, film laying and fixing Please refer to Figure 2 , a water-permeable but sand-impermeable fiber geomembrane roll is laid on top of the initially formed soil pile with a grass-laying machine, and the edge of the membrane covers at least 10 cm from the bottom of the soil pile. The edge of the membrane is fixed with wooden nails of about 20-30 cm, and the wooden nails are spaced 50-100 cm apart along the length of the soil pile. Among them, the fiber geomembrane can be LDPE (low-density polyethylene) as the geomembrane substrate, and the plant fiber is directly pierced into the geomembrane by needle puncture, so that the two are tightly combined to obtain a fiber geomembrane. Specifically, the diameter of the plant fiber is about 0.1-2 mm, the aspect ratio is 50-150, the distribution density of the plant fiber on the surface of the geomembrane is 100-300 roots / square meter, and the depth of penetration into the substrate should be controlled at 50%-80% of the thickness of the substrate. The plant fiber is directly pierced into the LDPE substrate by a needle puncture process. During the needle puncture process, the substrate is softened by heat (the temperature is controlled at 80℃-120℃), so that the fiber is embedded in the substrate and then cooled and solidified to form a physical anchoring structure without the need for additional adhesives.

[0031] S3, reinforcement molding Use spraying equipment to evenly spray the EICP slurry on the surface of the fiber geomembrane. The application amount is controlled at 1 L / m² each time. Spray once a day for 3 consecutive days to build a Figure 3 (a) shows the strip-shaped sand barrier; the spacing L of the strip-shaped sand barrier is 1.5 m, the height h of the strip-shaped sand barrier is 15 cm, and the slope θ is 10°. The EICP slurry used is composed of urease and cementing liquid (urea and calcium chloride), and the volume ratio of urease to cementing liquid is 1:1; the concentrations of cementing liquid are 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, and 0.4 mol / L, respectively, and the ratio of urea to calcium chloride in the cementing liquid is 1.5:1; urease is extracted from soybeans, and the urease activity is about 5 U / mL. At the same time, pure water is used instead of EICP slurry as a control group.

[0032] A wind tunnel test was conducted using a fan to test the wind erosion rate of the strip-shaped sand barrier of this embodiment. The definitions of wind level and corresponding wind speed are shown in Table 1. First, the wind speed was calibrated to the specified value, and then the sample was placed in the fan. The wind erosion test lasted for 30 minutes, and the sample mass was measured and recorded after the test.

[0033] Table 1 Wind levels and corresponding wind speeds The results are as follows Figure 5 As shown in the figure, the higher the concentration of the binder (CS), the more times of reinforcement, the lower the wind erosion rate of the sand barrier, and the better the wind erosion resistance. Therefore, the most cost-effective option is CS concentration of 0.1 mol / L and reinforcement twice.

[0034] Example 3 Effects of different sand barrier orientations on ecological sand barriers Figure 1 For a schematic diagram of the construction process of the ecological sand barrier proposed in the embodiment of the present invention, please refer to Figure 1 According to a specific embodiment of the present invention, a method for constructing an ecological sand barrier based on biologically induced calcium carbonate precipitation comprises the following steps: S1. Preliminary formation of soil pile The straw fiber is cut to 1-5 cm, and the addition ratio of straw fiber is 0.4% of the mass of sand. The straw fiber is evenly added to the sand by means of rotary stirring. Then, the sand and the straw fiber are piled into strip-shaped soil piles, wavy soil piles or chessboard-shaped soil piles by a bulldozer during the pushing process. Then, a certain amount of water (0.5L / m²) is sprayed to make the soil pile initially formed. Among them, the rotary stirring method can be a double-shaft paddle mixer; two parallel stirring shafts pass through both sides of the stirring tank, and staggered paddles are evenly distributed on the shafts. The two stirring shafts rotate synchronously or in the opposite direction. Through the interaction of the paddles, the materials are forced to be mixed by convection, so that the materials can be evenly mixed in a short time.

[0035] S2, film laying and fixing Please refer to Figure 2, a water-permeable but sand-impermeable fiber geomembrane roll is laid on top of the initially formed soil pile with a grass-laying machine, and the edge of the membrane covers at least 10 cm from the bottom of the soil pile. The edge of the membrane is fixed with wooden nails of about 20-30 cm, and the wooden nails are spaced 50-100 cm apart along the length of the soil pile. Among them, the fiber geomembrane can be LDPE (low-density polyethylene) as the geomembrane substrate, and the plant fiber is directly pierced into the geomembrane by needle puncture, so that the two are tightly combined to obtain a fiber geomembrane. Specifically, the diameter of the plant fiber is about 0.1-2 mm, the aspect ratio is 50-150, the distribution density of the plant fiber on the surface of the geomembrane is 100-300 roots / square meter, and the depth of penetration into the substrate should be controlled at 50%-80% of the thickness of the substrate. The plant fiber is directly pierced into the LDPE substrate by a needle puncture process. During the needle puncture process, the substrate is softened by heat (the temperature is controlled at 80℃-120℃), so that the fiber is embedded in the substrate and then cooled and solidified to form a physical anchoring structure without the need for additional adhesives.

[0036] S3, reinforcement molding Use spraying equipment to evenly spray the EICP slurry on the surface of the fiber geomembrane. The application amount is controlled at 1 L / m² each time. Spray once a day for 3 consecutive days to construct the following Figure 3 The strip-shaped sand barrier shown in (a) Figure 3 (b) The wavy sand barrier shown in Figure 3 (c) shows a chessboard-like sand barrier; the slope θ, height h and distance L between each sand barrier are as follows Figure 3 As shown in (e), the spacing L is 1.5 m, the height h is 15 cm, and the slope θ is 30°; the angle α and amplitude A of the sinusoidal wave strip unit are as follows Figure 3 As shown in (d), the angle α is 45° and the amplitude A is 50 cm; the EICP slurry used is composed of urease and binder (urea and calcium chloride), and the volume ratio of urease to binder is 1:1; the concentration of the binder is 0.1 mol / L, and the ratio of urea to calcium chloride in the binder is 1.5:1; the urease is extracted from soybean, and the urease activity is about 5 U / mL.

[0037] The wind erosion rate test was carried out on the sand barrier of this embodiment, and the results are as follows: Figure 7 As shown in the figure, the wavy sand barrier reduces the wind erosion rate by about 30% compared with the strip-shaped one, and the chessboard-shaped one can reduce it by another 20%.

[0038] In summary, according to the embodiments of the present invention, the calcium carbonate cementing layer formed by EICP / EICP significantly improves the soil's resistance to wind erosion, the fibers limit the displacement of sand and soil, improve the tensile strength and toughness, and the fiber geomembrane further plays an anti-wind protection role, so that the wind erosion resistance and durability of the constructed ecological sand barrier are enhanced; in addition, the ecological sand barrier is constructed using desert in-situ sand and plant fibers to reduce dependence on external materials and transportation, improve construction efficiency, reduce costs, and the layout of the sand barrier can be flexibly adjusted according to the terrain.

[0039] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms should not be understood as necessarily referring to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0040] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for constructing an ecological sand barrier based on biologically induced calcium carbonate precipitation, characterized in that: The following steps are involved: Mixing chopped plant fibers with sand to obtain a mixture; Using a bulldozer to pile the mixture into a string-shaped soil pile, and spraying water on the string-shaped soil pile to preliminarily shape the soil pile; Covering the fiber geomembrane on the initially formed string-shaped soil pile, and fixing the fiber geomembrane with wooden nails; The EICP slurry or the MICP slurry is uniformly sprayed on the outer surface of the fiber geomembrane, and the EICP slurry or the MICP slurry penetrates into the string-shaped soil pile, so that the string-shaped soil pile is solidified and bonded with the fiber geomembrane to form an ecological sand barrier.

2. The method for constructing an ecological sand barrier based on biologically induced calcium carbonate precipitation according to claim 1, characterized in that: The plant fiber comprises at least one of straw fiber, coconut shell fiber and hemp fiber; the length of the chopped plant fiber is 1 cm-15 cm.

3. The method for constructing an ecological sand barrier based on biologically induced calcium carbonate precipitation according to claim 1, characterized in that: The added amount of the plant fiber is 0.2%-0.6% of the mass of the sand.

4. The method for constructing an ecological sand barrier based on biologically induced calcium carbonate precipitation according to any one of claims 1 to 3, characterized in that: The plant fiber and the sand are mixed in a rotating stirring manner.

5. The method for constructing an ecological sand barrier based on biologically induced calcium carbonate precipitation according to claim 1, characterized in that: The string-shaped soil mound is a strip-shaped soil mound, a wave-shaped soil mound or a chessboard-shaped soil mound.

6. The method for constructing an ecological sand barrier based on biologically induced calcium carbonate precipitation according to claim 1, characterized in that: The fiber geomembrane has water-permeable micropores which are permeable to water but impermeable to sand and soil.

7. The method for constructing an ecological sand barrier based on biologically induced calcium carbonate precipitation according to claim 1 or 6, characterized in that: The edge of the fiber geomembrane covers at least 10 cm of the bottom of the chord-shaped soil pile. The wooden nails are set at the edge of the fiber geomembrane and arranged at intervals along the length direction of the chord-shaped soil pile. The distance between two adjacent wooden nails is 50 cm-100 cm.

8. The method for constructing an ecological sand barrier based on biologically induced calcium carbonate precipitation according to claim 1, characterized in that: The EICP slurry is formed by mixing urease and a binder in a volume ratio of 1:1, the concentration of the binder is 0.1mol / L-0.4mol / L, and the urease activity is 5 U / mL-10 U / mL; the MICP slurry is formed by mixing Bacillus pasteurianus bacterial solution and a binder in a volume ratio of 1:1, the concentration of the binder is 0.1mol / L-0.4mol / L, and the activity of the Bacillus pasteurianus bacterial solution is 5 U / mL-10 U / mL.

9. The method for constructing an ecological sand barrier based on biologically induced calcium carbonate precipitation according to claim 1 or 8, characterized in that: The application amount of the EICP slurry or the MICP slurry is 1 L-3 L per square meter; the EICP slurry or the MICP slurry is applied by spraying.

10. An ecological sand barrier, characterized in that: The ecological sand barrier is constructed by using the construction method of any one of claims 1 to 9 based on biologically induced calcium carbonate precipitation, wherein the ecological sand barrier comprises: A string-shaped soil pile, wherein the string-shaped soil pile is mixed with plant fiber and sand and solidified by EICP slurry or MICP slurry; A fiber geomembrane, wherein the fiber geomembrane covers the outer surface of the chord-shaped soil pile and is bonded to the chord-shaped soil pile through the EICP slurry or the MICP slurry; Wooden nails are arranged at the edge of the fiber geomembrane to fix the fiber geomembrane to the sand.

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