An ecological sand barrier based on biologically induced calcium carbonate precipitation and its construction method

Abstract

The present invention discloses an ecological sand barrier based on biologically induced calcium carbonate precipitation and a construction method thereof. The construction method comprises: mixing chopped plant fibers with sand to obtain a mixture; using a bulldozer to pile the mixture into a string-shaped mound, and spraying water on the string-shaped mound to initially shape the mound; covering the initially formed string-shaped mound with a fiber geomembrane and securing the fiber geomembrane with wooden nails; and uniformly spraying an EICP slurry or a MICP slurry on the outer surface of the fiber geomembrane. The EICP slurry or the MICP slurry penetrates into the string-shaped mound, solidifying the string-shaped mound and bonding it with the fiber geomembrane to form an ecological sand barrier. This method achieves the low-cost, high-efficiency goals of resource utilization and desert control. Furthermore, the constructed ecological sand barrier has both rigidity and toughness, strong wind erosion resistance, and excellent durability.

Description

Technical Field

[0001] The present 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 a global ecological and environmental issue, threatening agriculture, ecosystems, and human habitats. To control desert expansion and restore ecosystems, a variety of sand fixation technologies have been developed, including clay sand barriers, grass grid sand barriers, and chemical sand fixation agents.

[0003] Clay sand barriers and straw grid sand barriers are currently the most common sand fixation methods. Clay sand barriers reduce wind erosion by constructing clay ridges on the sand surface and forming a stable vortex structure within the barrier to accumulate sand. However, this technology relies on large quantities of clay resources, requiring long-distance transportation and mechanical handling for accumulation. This leads to high construction costs, low efficiency, and susceptibility to erosion, resulting in a limited service life. While straw grid sand barriers are less expensive, their durability and wind resistance are limited, and they require a high resource requirement 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 desertification control due to their environmentally friendly nature and high reinforcement performance. MICP / EICP uses microorganisms or enzymes to induce the decomposition of urea, producing calcium carbonate precipitation, which cements soil particles and improves their erosion resistance. Research has shown that MICP / EICP can significantly enhance the shear and compressive strength of soil, but the treated soil may still have some brittleness. Furthermore, applying EICP / MICP to a full area of ​​sand fixation is costly and prone to localized damage, resulting in poor durability. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of related technologies in constructing sand barriers in material handling and construction efficiency, and to achieve the low-cost and 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] To achieve the above objectives, the present invention provides, in a first aspect, a method for constructing an ecological sand barrier based on biologically induced calcium carbonate precipitation, comprising the following steps:

[0007] Mixing chopped plant fibers with sand to obtain a mixture;

[0008] piling the mixture into a string-shaped soil pile using a bulldozer, and spraying water on the string-shaped soil pile to preliminarily shape the soil pile;

[0009] Covering the fiber geomembrane on the initially formed string-shaped soil pile and fixing the fiber geomembrane with wooden nails;

[0010] EICP slurry or MICP slurry is evenly 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.

[0011] According to an embodiment of the present invention, a method for constructing an ecological sand barrier based on biologically induced calcium carbonate precipitation is described. The method first adds plant fibers to sand and mixes them. Then, a bulldozer is used to pile the sand and fibers into a string-shaped soil pile during the propulsion process. A certain amount of water is then sprayed to initially form the soil pile. A fiber geomembrane is then laid to cover the string-shaped soil pile. Finally, an EICP slurry or MICP slurry is sprayed to reinforce the soil pile to form a fiber-reinforced ecological sand barrier. The calcium carbonate cementation layer formed by EICP / MICP can significantly improve the soil's resistance to wind erosion and reduce the wind erosion problem of traditional sand barriers. The plant fibers can limit the displacement of sand, improve tensile strength and toughness, and solve the problem of brittle failure of single EICP / MICP technology. In other words, calcium carbonate precipitation fills pores and cements soil particles to form a stable structure. The fibers act as a bridge, further connecting soil particles and calcium carbonate crystals, thereby improving soil toughness. In addition, the fiber geomembrane further plays a role in wind protection. As a result, 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 allowing the layout of sand barriers to be flexibly adjusted according to the terrain.

[0012] 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.

[0013] Optionally, the added amount of the plant fiber is 0.2%-0.6% of the mass of the sand.

[0014] Optionally, the plant fibers and the sand are mixed by rotating and stirring.

[0015] Optionally, the string-shaped soil mound is a strip-shaped soil mound, a wave-shaped soil mound or a chessboard-shaped soil mound.

[0016] Optionally, the fiber geomembrane has water-permeable micropores that are permeable to water but not to sand.

[0017] Optionally, the edge of the fiber geomembrane covers at least 10 cm of the bottom of the string-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 string-shaped soil pile, and the distance between two adjacent wooden nails is 50 cm-100 cm.

[0018] 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 liquid 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 liquid is 5 U / mL-10 U / mL.

[0019] Optionally, the application amount of the EICP slurry or the MICP slurry is 1 L to 3 L per square meter; the EICP slurry or the MICP slurry is applied by spraying.

[0020] In a second aspect, the present invention provides an ecological sand barrier constructed using the above-mentioned method for constructing an ecological sand barrier based on biologically induced calcium carbonate precipitation. The ecological sand barrier comprises:

[0021] 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;

[0022] a fiber geomembrane, the fiber geomembrane covering the outer surface of the chord-shaped soil pile and being bonded to the chord-shaped soil pile by the EICP slurry or the MICP slurry;

[0023] Wooden nails are arranged at the edge of the fiber geomembrane to fix the fiber geomembrane to the sand.

[0024] The ecological sand barrier according to the embodiment of the present invention has both rigidity and toughness, strong wind erosion resistance 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 and high-efficiency goals of resource utilization and desert control.

[0025] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 2. It is a schematic diagram of the construction process of the ecological sand barrier according to an embodiment of the present invention;

[0027] Figure 2 is a cross-sectional view of an ecological sand barrier according to an embodiment of the present invention;

[0028] Figure 3 : The orientation and parameters of the ecological sand barrier according to an embodiment of the present invention include: (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;

[0029] 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;

[0030] 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 an embodiment of the present invention;

[0031] Figure 6 is a microscopic structural diagram of an ecological sand barrier according to an embodiment of the present invention;

[0032] Figure 7 This is the impact of different sand barrier orientations on the wind erosion rate of ecological sand barriers according to an embodiment of the present invention. DETAILED DESCRIPTION

[0033] 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 presence 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 define the scope of the present invention. Changes or adjustments in their relative relationships, without substantially changing the technical content, should also be regarded as the scope of the present invention.

[0034] In order to better understand the above technical solutions, 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 to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0035] The test materials used in the present invention are all common commercial products and can be purchased in the market.

[0036] 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 local damage is easy, resulting in poor durability. This application provides a method for constructing an ecological sand barrier based on biologically induced calcium carbonate precipitation. In this method, Figure 6 As shown, when constructing an ecological sand barrier, calcium carbonate precipitation fills the pores and cements the soil particles to form a stable structure. Plant fibers play a bridging role, further connecting the soil particles and calcium carbonate crystals, thereby improving the toughness of the soil. The fiber geomembrane further plays a role in wind protection. Thus, the calcium carbonate cementing layer formed by the EICP slurry or 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 utilizes plant fibers to limit the displacement of sand and soil, thereby improving 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.

[0037] The present invention is described below with reference to specific examples. It should be noted that these examples are merely illustrative and do not limit the present invention in any way.

[0038] Example 1 Effects of different fiber lengths, contents, and reinforcement times on ecological sand barriers

[0039] 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 includes the following steps:

[0040] S1. Initial formation of soil mound

[0041] The straw fibers are cut into lengths of 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 mound by a bulldozer during the propulsion process, followed by spraying a certain amount of water (0.5 L / m²) to initially form the mound. In this embodiment, the bulldozer's travel path is strip-shaped. 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 blades are evenly distributed on the shafts. The two stirring shafts rotate synchronously or in opposite directions. Through the interaction of the blades, the material is forced to undergo convection stirring, so that the material is evenly mixed in a short time.

[0042] S2, film laying and fixing

[0043] Please refer to Figure 2 A roll of a water-permeable, sand-impermeable fiber geomembrane is laid over the pre-formed soil pile using a grass-laying machine. The membrane edge covers the bottom of the pile by at least 10 cm. Wooden pegs approximately 20-30 cm long are used to secure the membrane edge, spaced 50-100 cm apart along the length of the pile. The fiber geomembrane can be made of LDPE (low-density polyethylene) as the base material. Plant fibers are directly inserted into the geomembrane through a needle-punch process, creating a tight bond between the two. Specifically, the plant fibers have a diameter of approximately 0.1-2 mm and an aspect ratio of 50-150. The density of the plant fibers on the geomembrane surface is 100-300 fibers per square meter, and the penetration depth should be controlled to 50%-80% of the base material thickness. The plant fibers are inserted directly into the LDPE base material through the needle-punch process. During the needle-punch process, the base material softens due to heat (controlled at 80°C-120°C). The fibers are embedded in the base material and then solidify upon cooling, forming a physical anchoring structure without the need for additional adhesive.

[0044] S3, reinforcement molding

[0045] Use spraying equipment to evenly spray EICP slurry on the surface of 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 a strip-shaped sand barrier with a spacing of 1.5 m, a height of 15 cm, and a slope of 10°. The EICP slurry used consisted of urease and a binder (urea and calcium chloride) in a 1:1 volume ratio. The binder concentration was 0.2 mol / L, and the ratio of urea to calcium chloride was 1.5:1. The urease was extracted from soybeans, with a urease activity of approximately 5 U / mL.

[0046] The surface strength of the sand slope of the strip sand barrier is tested regularly using a micro penetrometer. 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, which is three reinforcement times, 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.

[0047] Example 2 Effects of different binder concentrations and different reinforcement times on ecological sand barriers

[0048] 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 1According to a specific embodiment of the present invention, a method for constructing an ecological sand barrier based on biologically induced calcium carbonate precipitation includes the following steps:

[0049] S1. Initial formation of soil mound

[0050] The straw fibers are cut into 1-5 cm thick, and the addition ratio of the straw fibers is 0.4% of the mass of the sand. The straw fibers are evenly added to the sand by means of rotary stirring. Then, a bulldozer is used to pile the sand and the straw fibers into a strip-shaped mound during the propulsion process. Then, a certain amount of water (0.5 L / m²) is sprayed to initially form the mound. In this embodiment, the bulldozer's travel path 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 opposite directions. Through the interaction of the blades, the material is forced to undergo convection stirring, so that the material is evenly mixed in a short time.

[0051] S2, film laying and fixing

[0052] Please refer to Figure 2 A roll of a water-permeable, sand-impermeable fiber geomembrane is laid over the pre-formed soil pile using a grass-laying machine, with the membrane edge covering at least 10 cm from the bottom of the pile. Wooden pegs approximately 20-30 cm long are used to secure the membrane edge, spaced 50-100 cm apart along the length of the pile. The fiber geomembrane can be made of LDPE (low-density polyethylene) as the base material. Plant fibers are directly inserted into the geomembrane through a needle-punch process, creating a tight bond between the two. Specifically, the plant fibers have a diameter of approximately 0.1-2 mm and an aspect ratio of 50-150. The density of the plant fibers on the geomembrane surface is 100-300 fibers per square meter, and the penetration depth should be controlled to 50%-80% of the base material thickness. The plant fibers are inserted directly into the LDPE base material through the needle-punch process. During the needle-punch process, the base material softens due to heat (controlled at 80°C-120°C). The fibers are embedded in the base material and then solidify after cooling, forming a physical anchoring structure without the need for additional adhesive.

[0053] S3, reinforcement molding

[0054] Use spraying equipment to evenly spray EICP slurry on the surface of 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 a strip-shaped sand barrier with a spacing of 1.5 m, a height of 15 cm, and a slope of 10°. The EICP slurry used consisted of urease and a binder (urea and calcium chloride) at a volume ratio of 1:1. The binder concentrations were 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 was 1.5:1. Urease was extracted from soybeans, with a urease activity of approximately 5 U / mL. Pure water was used instead of the EICP slurry as a control.

[0055] A wind tunnel test using a fan was conducted to test the wind erosion rate of the strip-shaped sand barrier of this embodiment. The definitions of wind levels and corresponding wind speeds are shown in Table 1. The wind speed was first calibrated to the specified value, and then the sample was placed in the fan. The wind erosion test lasted for 30 minutes, after which the sample mass was measured and recorded.

[0056] Table 1 Wind levels and corresponding wind speeds

[0057]

[0058] The results are as follows Figure 5 As shown in the figure, the higher the CS concentration, the more reinforcement times, the lower the wind erosion rate of the sand barrier, and the better the wind erosion resistance. Therefore, the most cost-effective option is a CS concentration of 0.1 mol / L and two reinforcement times.

[0059] Example 3 Effects of different sand barrier orientations on ecological sand barriers

[0060] 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 includes the following steps:

[0061] S1. Initial formation of soil mound

[0062] The straw fibers are cut to 1-5 cm in thickness, with the addition ratio of straw fibers to the sand being 0.4% by mass. The straw fibers are evenly added to the sand using a rotary stirring method. A bulldozer then pushes the sand and straw fibers into strip-shaped, wavy, or chessboard-shaped mounds. A certain amount of water (0.5 L / m²) is then sprayed to initially shape the mounds. The rotary stirring method can be a twin-shaft paddle mixer. Two parallel stirring shafts extend through the sides of the mixing tank, with staggered blades evenly distributed on the shafts. The two stirring shafts rotate synchronously or counter-rotatingly, and the interaction of the blades creates forced convection stirring on the material, achieving uniform mixing in a short period of time.

[0063] S2, film laying and fixing

[0064] Please refer to Figure 2 A roll of a water-permeable, sand-impermeable fiber geomembrane is laid over the pre-formed soil pile using a grass-laying machine, with the membrane edge covering at least 10 cm from the bottom of the pile. Wooden pegs approximately 20-30 cm long are used to secure the membrane edge, spaced 50-100 cm apart along the length of the pile. The fiber geomembrane can be made of LDPE (low-density polyethylene) as the base material. Plant fibers are directly inserted into the geomembrane through a needle-punch process, creating a tight bond between the two. Specifically, the plant fibers have a diameter of approximately 0.1-2 mm and an aspect ratio of 50-150. The density of the plant fibers on the geomembrane surface is 100-300 fibers per square meter, and the penetration depth should be controlled to 50%-80% of the base material thickness. The plant fibers are inserted directly into the LDPE base material through the needle-punch process. During the needle-punch process, the base material softens due to heat (controlled at 80°C-120°C). The fibers are embedded in the base material and then solidify after cooling, forming a physical anchoring structure without the need for additional adhesive.

[0065] S3, reinforcement molding

[0066] Use spraying equipment to evenly spray EICP slurry on the surface of fiber geomembrane. The application amount is controlled at 1 L / m² each time. Spray once a day for 3 consecutive days to build the following Figure 3 (a) The strip-shaped sand barrier, Figure 3 (b) The wavy sand barrier shown in Figure 3 (c) The chessboard-like sand barriers shown; 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 consists 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.

[0067] The wind erosion rate test of the sand barrier in this embodiment was carried out, and the results were 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 checkerboard-shaped one can reduce it by another 20%.

[0068] 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, 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, which reduces dependence on external materials and transportation, improves construction efficiency, reduces costs, and can flexibly adjust the layout of the sand barrier according to the terrain.

[0069] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" mean 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 expressions 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 can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification.

[0070] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify 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; piling the mixture into a string-shaped soil pile using a bulldozer, 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; Evenly spraying EICP slurry or MICP slurry on the outer surface of the fiber geomembrane, wherein the EICP slurry or the MICP slurry penetrates into the string-shaped soil pile, so that the string-shaped soil pile solidifies and bonds with the fiber geomembrane to form an ecological sand barrier; The fiber geomembrane is produced in the following manner: plant fibers with a diameter of 0.1-2 mm and an aspect ratio of 50-150 are directly inserted into an LDPE substrate through a needle punching process, and the depth of the insertion into the substrate is 50%-80% of the thickness of the substrate. During the needle punching process, the substrate is softened by heat, and the plant fibers are embedded in the substrate and then cooled and solidified to form permeable micropores that are permeable to water but not to sand.

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 fibers include at least one of straw fibers, coconut shell fibers, and hemp fibers; and the length of the chopped plant fibers is 1 cm to 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 fibers 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 edge of the fiber geomembrane covers at least 10 cm of the bottom of the string-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 string-shaped soil pile. The distance between two adjacent wooden nails is 50 cm-100 cm.

7. 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 liquid 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 liquid is 5 U / mL-10 U / mL.

8. The method for constructing an ecological sand barrier based on biologically induced calcium carbonate precipitation according to claim 1 or 7, characterized in that: The application amount of the EICP slurry or the MICP slurry is 1 L to 3 L per square meter; the EICP slurry or the MICP slurry is applied by spraying.

9. An ecological sand barrier, characterized in that: The ecological sand barrier is constructed using the method for constructing an ecological sand barrier based on biologically induced calcium carbonate precipitation according to any one of claims 1 to 8, 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, the fiber geomembrane covering the outer surface of the chord-shaped soil pile and being bonded to the chord-shaped soil pile by 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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