Bamboo grid

Abstract

The invention discloses a bamboo grid, and belongs to the technical field of desertification control engineering. The bamboo checks are square bamboo checks formed by connecting two L-shaped or four linear bamboo sand barriers end to end; the side length of each bamboo grid is 500-2000mm; the bamboo sand barrier is of a warp and weft interwoven net-shaped structure composed of weaving lines and bamboo sheets. The length of each bamboo sheet ranges from 200 mm to 600 mm; the length-to-thickness ratio of the bamboo sheets is (100: 1)-(500: 1); a gap is formed between every two adjacent bamboo sheets, and the width of each gap is 0.2-2.2 times that of each bamboo sheet. The bamboo sheets are prepared by sectioning and processing bamboo tubes in the radial direction or the chordwise direction. According to the method, the three elements of the size of the bamboo grid unit, the gap width of the bamboo sheets and the embedding depth are synergistically optimized, a three-dimensional sand stabilization network with the gradient wind resistance effect is constructed, and a long-acting sand stabilization system with high environmental adaptability is formed.

Description

Technical Field

[0001] The present invention relates to the technical field of desertification control engineering, and particularly to a bamboo grid. Background Art

[0002] Sand barriers are one of the key technologies for desertification control, and the selection of materials and optimization of their performance directly affect the sand fixation effect and the efficiency of ecological restoration. The straw checkerboard (also known as "straw checkerboard sand barrier") is an ecological engineering method for wind prevention and sand fixation and desertification control, mainly applied to the deserts or the edges of sandy lands in arid and semi-arid regions. Usually, plant straws such as wheat straw, rice straw, and reed are used, which are tied into a grid shape and semi-buried in the sandy land. The straw checkerboard is generally 1m×1m or 2m×2m, forming a network structure, which can effectively fix mobile sand dunes, prevent sand grains from moving with the wind; reduce the evaporation of surface water, improve the local microclimate; create conditions for the subsequent growth of plants, promote ecological restoration, and has the advantages of easy availability of materials, low cost, and natural degradability. It is widely used in the governance projects along the Lanzhou-Xinjiang Railway, both sides of the Taklimakan Desert Highway, and in the Mu Us Sandy Land and Kubuqi Desert, and has been popularized in regions such as Africa (such as the Sahara Desert), the Middle East (such as the United Arab Emirates), and Central Asia (such as Kazakhstan). It is an important invention in China's desert control project and has been promoted by the United Nations Environment Programme as a global desert control model. The straw checkerboard has the following disadvantages:

[0003] (1) Limited durability and requires regular maintenance;

[0004] The materials of the straw checkerboard (such as wheat straw, rice straw, etc.) will naturally rot and generally can only last for 3 to 5 years, after which it needs to be re-laid. In areas with strong wind and sand, some straw checkerboards may be overturned by strong winds or buried by sand, resulting in a decline in the protection effect.

[0005] (2) Dependent on manual labor, high cost for large-scale promotion;

[0006] The laying of the straw checkerboard mainly relies on manual labor, which has a high labor intensity and low efficiency in the desert environment.

[0007] Although the single laying cost is relatively low, long-term maintenance (such as replanting, replacement) will increase the overall cost.

[0008] (3) Limited by materials, insufficient supply in some areas;

[0009] The straw checkerboard requires a large amount of plant straws such as wheat straw and reed, but in some severely desertified areas, such materials may be in short supply and need to be transported from other places, increasing the cost. If chemical materials (such as plastic grids) are used for substitution, it may bring environmental pollution problems.

[0010] (4) The effect of a single measure is limited and needs to be combined with other methods;

[0011] The straw checkerboard mainly plays a role in short-term sand fixation. Without subsequent vegetation restoration (such as planting drought-tolerant plants), the sandy land may still flow again. In extremely arid areas, it is difficult to stabilize the sand dunes for a long time relying solely on the straw checkerboard, and irrigation, sand barriers + plant composite measures, etc. are required.

[0012] (5) Ecological impact;

[0013] If the straw used contains pesticide residues (such as rice straw in some farmlands), it may affect the sandy land microorganisms and small animals. Summary of the Invention

[0014] In view of this, the present invention provides a bamboo checkerboard, and the main purpose is to provide a new sand control material and new structure with high strength, good toughness, and can be prepared on a large scale by mechanization.

[0015] The present invention provides a bamboo checkerboard, which is formed by connecting the ends of 2 L-shaped or 4 straight-shaped bamboo sand barriers end to end to form a square-shaped bamboo checkerboard; the side length of the bamboo checkerboard is 500 - 1000 mm;

[0016] The bamboo sand barrier is a net-like structure formed by the warp and weft interweaving of a braided line and bamboo slices, and the bamboo slices are arranged parallel along the longitudinal direction; the braided line is arranged along the direction perpendicular to the extension direction of the bamboo slices, and the braided line is arranged at least one on the bamboo slices;

[0017] The length of the bamboo slice is 200 - 600 mm;

[0018] The ratio of the length to the thickness of the bamboo slice is (100:1) - (500:1);

[0019] There is a gap between adjacent bamboo slices, and the width of the gap is 0.2 - 2.2 times the width of the bamboo slice.

[0020] According to the foregoing bamboo checkerboard, the buried length of the bamboo slices in the bamboo checkerboard is 40 - 50% of the length of the bamboo slice.

[0021] According to the foregoing bamboo checkerboard, the bamboo slice is prepared by cutting the bamboo tube along the radial direction; the cross-section of the bamboo slice is a fan-shaped ring; the side surface of the bamboo slice is an outer arc surface, an inner arc surface, and a side plane between the outer arc surface and the inner arc surface; the outer arc surface and / or the inner arc surface face the extension direction of the braided line;

[0022] In the cross-section of the bamboo slice, the distance between the two farthest endpoints of the outer arc surface is the thickness b, and the distance between the endpoint where the side plane is connected to the outer arc surface and the endpoint where the side plane is connected to the inner arc surface is the width w;

[0023] The ratio of the width to the thickness of the bamboo slice is (5:1) - (25:1).

[0024] Further, the thickness of the bamboo slice is 0.8 - 4.0 mm.

[0025] Furthermore, the outer arc surfaces and / or inner arc surfaces of all the bamboo strips in the bamboo sand barrier face in the same direction.

[0026] Furthermore, the outer arc surfaces and / or inner arc surfaces of adjacent bamboo strips in the bamboo sand barrier face in opposite directions.

[0027] According to the aforementioned bamboo grid, the bamboo strips are prepared by cutting a bamboo tube along the chord direction;

[0028] The side surfaces of the bamboo strips are outer cut surfaces, inner cut surfaces, and side planes between the outer cut surface and the inner cut surface; the outer arc surface and / or inner arc surface face the extending direction of the braided line;

[0029] In the cross-section of the bamboo strip, the vertical distance between the outer cut surface and the inner cut surface is the thickness b, and the distance between the two end points of the outer cut surface is the width w;

[0030] The width-to-thickness ratio of the bamboo strip is (5:1) - (25:1).

[0031] According to the aforementioned bamboo grid, the braided line is one of a hemp rope and a cotton rope. When there are two braided lines, the gap width between the laterally adjacent braided lines is 10 - 30 cm.

[0032] According to the aforementioned bamboo grid, the surface of the bamboo strip is coated with an anti-ultraviolet coating;

[0033] The anti-ultraviolet coating contains titanium dioxide, benzotriazole ultraviolet light absorber, and silica sol, and the coating thickness is 50 - 100 nm.

[0034] According to the aforementioned bamboo grid, the length of the bamboo strip is 300 - 500 mm.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) By synergistically optimizing the three elements of the bamboo grid unit size, the gap width of the bamboo strips, and the embedding depth, the present invention constructs a three-dimensional sand fixation network with a gradient wind resistance effect, forming a long-term sand fixation system with strong environmental adaptability.

[0037] (2) By precisely controlling the range of geometric parameters of the bamboo strips, the bamboo strips can obtain the optimal elastic deformation ability while maintaining the bending strength of natural bamboo. On the one hand, under the action of strong wind, the bamboo strips are more likely to bend rather than break, which can disperse the wind pressure, extend the service life, and maintain the integrity of the sand fixation structure for a long time. On the other hand, the elastic bamboo strips will generate slight vibrations in the wind, which may further weaken the near-surface wind speed through turbulent disturbances and reduce the sand particle entrainment. In addition, when the bamboo strips are implanted into the sand layer in a specific arrangement, the unique fan-shaped ring cross-section morphology and elastic mechanical properties work together to effectively block the sand particle flow and form a lasting sand fixation network, which is suitable for the application of sand fixation materials in desertification control projects.

[0038] (3) The bamboo sand barrier prepared from the fan-shaped ring bamboo strips has good wind prevention and sand fixation effects. Compared with the rectangular bamboo strips, the inclined windward surface of the fan-shaped ring bamboo strips guides the airflow to deflect gently, causing the sand particles to slide along the surface and reducing the accumulation. Brief Description of the Drawings

[0039] Figure 1 is the on-site structure diagram of the bamboo grid sand barrier;

[0040] Figure 2 is the schematic structural diagram of the bamboo tube cut radially;

[0041] Figure 3 is the three-dimensional structural schematic diagram of the bamboo strip prepared by radial cutting;

[0042] Figure 4 is the transverse cross-sectional view of the bamboo strip prepared by radial cutting;

[0043] Figure 5 is the three-dimensional structural schematic diagram of a kind of bamboo sand barrier;

[0044] Figure 6 is the three-dimensional structural schematic diagram of another kind of bamboo sand barrier;

[0045] Figure 7 is the schematic structural diagram of the bamboo tube cut tangentially;

[0046] Figure 8 is the three-dimensional structural schematic diagram of the bamboo strip prepared by tangential cutting.

[0047] Description of the Reference Numerals:

[0048] 100, bamboo strip; 101, outer arc surface; 102, inner arc surface; 103, side plane; 104, outer cutting plane; 105, inner cutting plane;

[0049] 200, knitting thread. Detailed Embodiments

[0050] To make the technical problems, technical solutions, and advantages to be solved by the present invention clearer, the following will describe the technical solutions of the present invention clearly and completely in conjunction with the drawings Figures 1 to 8 and specific embodiments.

[0051] The present invention provides a bamboo grid, Figure 1 which is a site structure diagram of a bamboo grid sand barrier.

[0052] The bamboo grid is formed by connecting the ends of 2 L-shaped or 4 straight-shaped bamboo sand barriers to form a square-shaped bamboo grid; the side length of the bamboo grid is 500 - 1000 mm;

[0053] The bamboo sand barrier is a net-like structure formed by the interweaving of warp and weft of a braided line 200 and bamboo strips 100. The bamboo strips 100 are arranged parallel in the longitudinal direction; the braided line 200 is arranged along the direction perpendicular to the extension direction of the bamboo strips 100, and at least one braided line 200 is provided on the bamboo strips 100;

[0054] The distance from one end to the other end in the extension direction of the bamboo strip 100 is the length;

[0055] The length of the bamboo strip 100 is 200 - 600 mm; preferably, the length of the bamboo strip is 300 - 500 mm;

[0056] The ratio of the length to the thickness of the bamboo strip is (100:1) - (500:1);

[0057] There is a gap between adjacent bamboo strips 100, and the width of the gap is 0.2 - 2.2 times the width of the bamboo strip.

[0058] Furthermore, the buried length of the bamboo strip 100 in the bamboo grid is 40 - 50% of the length of the bamboo strip 100, and the buried length is the length buried in the sand layer.

[0059] Furthermore, the braided line 200 is one of a hemp rope and a cotton rope. When there are two braided lines 200, the width of the gap between the horizontally adjacent braided lines 200 is 10 - 30 cm

[0060] The bamboo strip 100 is prepared by cutting a bamboo tube along the radial or chordal direction. The outer arc surface and / or the inner arc surface of all the bamboo strips in the bamboo sand barrier face the same direction; or, the outer arc surface and / or the inner arc surface of the adjacent bamboo strips in the bamboo sand barrier face the opposite direction.

[0061] The first structure of the bamboo strip 100: The bamboo strip 100 is prepared by cutting a bamboo tube along the radial direction, as Figures 2 to 4As shown in the figure; the cross-section of the bamboo strip 100 is a sector ring; the side surface of the bamboo strip 100 is an outer arc surface 101, an inner arc surface 102, and a side plane 103 between the outer arc surface 101 and the inner arc surface 102; in the cross-section of the bamboo strip 100, the distance between the two farthest endpoints of the arc of the outer arc surface 101 is the thickness b, and the distance between the endpoint where the side plane 103 is connected to the outer arc surface 101 and the endpoint where the side plane 103 is connected to the inner arc surface 102 is the width w. The width-to-thickness ratio of the bamboo strip is (5:1) to (25:1). The thickness of the bamboo strip 100 is 0.8 to 4.0 mm.

[0062] The outer arc surface 101 and / or the inner arc surface 102 face the extending direction of the braided wire 200. Specifically, it can be divided into the following two situations:

[0063] The outer arc surfaces 101 and / or the inner arc surfaces 102 of all the bamboo strips 100 in the bamboo sand barrier face the same direction; the outer arc surfaces 101 and / or the inner arc surfaces 102 of adjacent bamboo strips 100 in the bamboo sand barrier face the opposite direction.

[0064] The following takes the sand barrier grid formed by the bamboo strip 100 of the present invention as Example 1 and the sand barrier grid formed by straw as Comparative Example 1 for description;

[0065] Among them, the elastic modulus and bending strength are tested in accordance with "Test Methods for Physical and Mechanical Properties of Bamboo (GB / T 15780~1995)", and the maximum bending moment and bending stress are tested by the uniaxial cantilever beam bending stress test method.

[0066] Example 1: Use the bamboo strip 100 to form a sand barrier grid. Among them, the bamboo strip 100 is dried to a moisture content of 8 to 30%, and two braided wires 200 are arranged on the bamboo strip 100; the braided wire 200 uses a cotton rope with a diameter of 2 mm, and the bamboo strip 100 is woven into a bamboo sand barrier curtain. The outer arc surface 101 and / or the inner arc surface 102 face the extending direction of the braided wire 200, and the outer arc surfaces 101 and / or the inner arc surfaces 102 of all the bamboo strips 100 face the same direction; the length of the bamboo strip 100 is 500 mm, the width w is 10 ± 2 mm, the thickness b is 2 mm, the distance between adjacent two bamboo strips 100 is 5 ± 2 mm, the size of the sand barrier grid is 1000 mm × 1000 mm, the length of the bamboo strip 100 inserted into the sand layer is 250 ± 30 mm, and the length of the bamboo strip 100 exposed above the sand layer is 250 ± 30 mm.

[0067] Comparative Example 1:

[0068] Use straw to form sand barrier squares. Among them, the diameter of the straw is 5±2mm, and it is cut into straw segments with a length of 500mm. Use cotton ropes with a diameter of 2mm to weave the straw into straw curtains. The gap width between the straws is 5±2mm, and it is inserted into the ground. The specifications of the straw squares are 1000×1000mm.

[0069] The basic mechanical properties of bamboo strips 100 and straw are shown in Table 1:

[0070] Table 1

[0071]

[0072] It can be seen from the data that: the initial interception efficiency of the straw sand barrier squares in Comparative Example 1 is 65-70%, but severe bending causes the gaps to close, and it completely fails after the structure breaks. The ventilation rate of the bamboo squares made of bamboo strips in Example 1 is reduced to 26.7%, the turbulence is enhanced by 15-20%, and the interception efficiency reaches 90-100%. The bamboo strips in Example 1 have higher stiffness and anti-deformation ability, can effectively resist the impact of wind and sand and the pressure of the sand layer, and avoid structural damage. The depth of the bamboo inserted into the sand layer (25±3 cm) is equal to the exposed part, forming a symmetrical support system with stronger anti-overturning ability; the straw is soft in texture and is prone to tilt or displacement after insertion. Through the high mechanical properties, precise structural design and environmental adaptability of the bamboo strips, the problems of easy deformation, ventilation rate failure and poor durability of the straw sand barrier are solved, and an efficient, stable and sustainable sand fixation effect is achieved. The high mechanical properties and safety factor of the bamboo sand barrier can significantly extend the service life and reduce the maintenance frequency; the straw sand barrier needs to be rebuilt frequently due to rapid failure, and the comprehensive cost is higher. In addition, bamboo is a renewable resource, and the processing process is low-carbon and environmentally friendly, which highly coincides with the ecological goal of desertification control.

[0073] The sand blocking effects of bamboo strips 100 and straw are shown in Table 2:

[0074] Table 2

[0075]

[0076] It can be seen from the data that: the interception efficiency of the straw squares fails, and the structural stability of 90-100% is low. It is suitable for short-term emergency scenarios and long-term projects in low wind speed areas (<8m / s) and strong wind and sand areas (>10m / s). Compared with straw, the bamboo strips 100 have good sand blocking effects.

[0077] Next, prove the technical effects of the geometric parameters of the bamboo strips 100 through experimental results:

[0078] Keep the aspect ratio of the bamboo strips 100 unchanged (the aspect ratio was controlled at 8 in the experiment), and study the change of the length-to-thickness ratio. Six examples and one comparative example were adopted in the experiment. The length of the bamboo strips 100 remained unchanged during the experiment, all being 600 mm, and the outer arc surface 101 and / or the inner arc surface 102 of all the bamboo strips 100 faced the same direction. The specific parameters (thickness, width, and length) are set in Table 3. At a wind speed of 20 m / s and a spacing of the bamboo strips 100 of 40% of the bamboo strip width, a wind tunnel test was used to study the performance of the bamboo strips 100 applied to the sand barrier. The length of the bamboo strips 100 inserted into the sand layer was 300 ± 30 mm, and the length of the bamboo strips 100 exposed above the sand layer was 300 ± 30 mm. The performance such as the bending stress, deflection, and sand blocking efficiency is shown in Table 3;

[0079] Material parameters: Elastic modulus E = 12.5 GPa, tensile strength σ b = 128 MPa;

[0080] Environmental parameters: Wind speed v = 20 m / s, air density ρ = 1.225 kg / m³;

[0081] Calculation formulas:

[0082] Ventilation rate: η = [s / (s + b)]²;

[0083] where s is the gap width between adjacent bamboo strips, and b is the width of the bamboo strip;

[0084] Wind load: F = 0.5ρv²C d ·(L·b);

[0085] where C d is the drag coefficient; L is the length of the bamboo strip exposed above the sand layer, that is, the distance from the sand layer surface to the top, taking half of the bamboo strip length, which is 300 mm;

[0086] Bending stress: σ = 6FL / (bw²);

[0087] Deflection: δ = 4FL³ / (Ebw³);

[0088] Safety factor: n = σ b / σ;

[0089] Sand blocking efficiency: E 阻 = η(1 - η)(1 - δ / 300).

[0090] Table 3

[0091]

[0092] It can be seen from the data that: In Example 3, the safety meets the standard, but the sand-blocking efficiency is significantly lower than that of thicker examples, and the cost and performance requirements need to be weighed. The safety factor of Example 2 is 23.2, the sand-blocking efficiency is 0.070, and the structure is critically safe, which is suitable for low-risk environments. Examples 4-6 (with a thickness of 1.8-2.2 mm and a length-to-thickness ratio of 270-330) have the best comprehensive performance: the safety factor far exceeds the safety threshold (>10); the sand-blocking efficiency is close to the theoretical peak; material efficiency: the thickness is moderate to avoid redundancy. The bamboo strip sand barrier has high wind resistance, high sand-blocking efficiency and reasonable cost within the range of (length-to-thickness ratio of 270-330), and is suitable for desertification control projects. The thickness of Comparative Example 2 is too small, resulting in excessive bending stress, low safety factor, deflection exceeding 300 mm, and the sand-blocking efficiency cannot be calculated according to the formula, and the structure fails. While the thickness of Example 7 is too large, the safety factor is too high, far exceeding the requirement ("excessive"), and the material redundancy significantly increases the cost, which is uneconomical in engineering. The failure of Comparative Example 2 and the excess of Example 7 warn that the design parameters need to be strictly controlled and dynamically optimized in combination with the actual wind and sand conditions.

[0093] Study the influence of the simultaneous change of the length-to-thickness ratio and the width-to-thickness ratio of the bamboo strip 100 on the performance of the bamboo strip 100 applied to the sand barrier. During the experiment, 5 examples and 2 comparative examples were used. The width of the bamboo strip 100 remained unchanged during the experiment, and the width was 20 mm. The outer arc surface 101 and / or the inner arc surface 102 of all the bamboo strips 100 faced the same direction. The specific parameters (thickness, width and length) are set in Table 4. When the wind speed is 20 m / s, the spacing of the bamboo strips 100 is 40% of the bamboo strip width, the length of the bamboo strip 100 inserted into the sand layer is 1 / 2 of the length of the bamboo strip 100, and the length of the bamboo strip 100 exposed above the sand layer is 1 / 2 of the length of the bamboo strip 100. The wind tunnel test was used to study the performance of the bamboo strip 100 applied to the sand barrier, and its performance (bending stress, deflection, safety factor, sand-blocking efficiency) is also shown in Table 4:

[0094] Table 4

[0095]

[0096] It can be seen from the data that: The width-to-thickness ratio and the length-to-thickness ratio jointly determine the wind resistance performance of the bamboo strip: as the width-to-thickness ratio decreases (thickness increases) and the length-to-thickness ratio decreases (thickness increases or length decreases), the bending stress decreases significantly.

[0097] Examples 8 - 9 (width - thickness ratio 20 - 25, thickness 0.8 - 1.0 mm): Safety factor 23.2 (critical safety), applicable to low - risk environments; Example 12 (width - thickness ratio 5, thickness 4.0 mm): Safety factor 256.0, sand - blocking efficiency 0.086, but with a relatively high material cost. Examples 10 - 11 (width - thickness ratio 10 - 12.5, thickness 1.6 - 2.0 mm, length - thickness ratio 300 - 375) have the best comprehensive performance: Safety far exceeds the safety threshold (>10); Sand - blocking efficiency: 0.083 - 0.085, close to the theoretical peak; Material efficiency: Moderate thickness, avoiding redundancy. The excess of Comparative Example 3 and the failure of Comparative Example 4 warn that the collaborative design of the width - thickness ratio and the length - thickness ratio needs to be strictly controlled, and dynamically optimized in combination with the actual wind - sand conditions.

[0098] The bamboo - strip sand barrier reaches the best balance among safety (safety factor > 40), sand - blocking efficiency (0.083 - 0.085) and material economy within the range of width - thickness ratio (10:1)-(12.5:1), with high wind - resistance, high sand - blocking efficiency and reasonable cost, and is applicable to desertification control projects.

[0099] By precisely controlling the geometric parameter range of the bamboo strip 100, the present invention enables the bamboo strip 100 to obtain the optimal elastic deformation ability while maintaining the bending strength of natural bamboo. On the one hand, under strong wind action, the bamboo strip 100 is more likely to bend rather than break, which can disperse the wind pressure, extend the service life, and maintain the integrity of the sand - fixation structure for a long time; on the other hand, the elastic bamboo strip 100 will generate tiny vibrations in the wind, which may further weaken the near - surface wind speed through turbulent perturbation and reduce the sand particle entrainment. In addition, when the bamboo strip 100 is implanted into the sand layer in a specific arrangement pattern, the unique fan - shaped ring cross - section morphology and elastic mechanical properties act synergistically to effectively block the sand particle flow and form a persistent sand - fixation network, which is applicable to the application of sand - fixation materials in desertification control projects.

[0100] The bamboo strip 100 from the outer ring to the inner ring is successively the bamboo green layer, the bamboo flesh layer and the bamboo yellow layer; the density of the bamboo flesh layer is distributed in a gradient from near the bamboo green layer to near the bamboo yellow layer, with the density near the bamboo green layer being 0.85 - 1.0 g / cm³ and the density near the bamboo yellow layer being 0.45 - 0.65 g / cm³. This density - gradient characteristic enables the high - density outer - ring area of the bamboo strip 100 to bear the compressive stress preferentially under loading, and the low - density inner - ring area absorbs energy through elastic deformation, forming a synergistic anti - impact mechanism similar to a "rigid - flexible composite layer", which can increase the anti - bending fatigue life by about 50% compared with homogeneous materials.

[0101] Example 13:

[0102] The width of the fan-shaped ring bamboo strip 100 is 12 mm, the thickness is 2 mm, the gap width between adjacent bamboo strips 100 is 6 mm, the outer arc surface 101 and / or the inner arc surface 102 of the adjacent bamboo strips 100 facing the extending direction of the braided wire 200 are in opposite directions, the outer arc surface 101 faces outward, and the inner arc surface 102 faces each other to form a "flare shape", as Figure 6 shown. Specifically, the width at the entrance is 6 mm, and the width at the exit is 5.83 mm. All the bamboo strips 100 are perpendicular to the ground. The length of the bamboo strip 100 inserted into the sand layer is 1 / 2 of the length of the bamboo strip 100, and the length of the bamboo strip 100 exposed above the sand layer is 1 / 2 of the length of the bamboo strip 100. The thickness direction is lateral, and the side plane 103 is the windward side. A wind tunnel test is adopted, and the ambient wind speed is 10 m / s.

[0103] Comparative Example 5:

[0104] The width of the rectangular bamboo piece is 12 mm, the thickness is 2 mm, and the edges are right angles; the gap width between adjacent rectangular bamboo pieces is 6 mm. The width direction surface of the rectangular bamboo piece is the windward side. The length of the bamboo strip 100 inserted into the sand layer is 1 / 2 of the length of the bamboo strip 100, and the length of the bamboo strip 100 exposed above the sand layer is 1 / 2 of the length of the bamboo strip 100. A wind tunnel test is adopted, and the ambient wind speed is 10 m / s.

[0105] The performances of the fan-shaped ring bamboo strips and the rectangular bamboo pieces are shown in Table 5:

[0106] Table 5

[0107]

[0108] It can be seen from the data that the fan-shaped ring bamboo strip sand barrier in Example 13 achieves significant technical advantages through the following innovative designs: forming a "flare shape" gap layout on the windward side, optimizing the air flow distribution, reducing the flow velocity and turbulence intensity; reducing rebound and enhancing deposition to form a dynamic equilibrium sand fixation system; having high structural durability, adapting to the long-term sandstorm environment, and reducing the maintenance cost. Compared with the rectangular bamboo piece, this design has achieved breakthroughs in sand fixation efficiency, environmental adaptability, and economy, providing a more efficient and sustainable solution for desertification control.

[0109] The second structure of the bamboo strip 100: The bamboo strip 100 is prepared by cutting the bamboo tube along the chord direction, as Figure 7 and Figure 8As shown in the figure; the cross-section of the bamboo veneer 100 is an isosceles trapezoid; the side surface of the bamboo veneer 100 is an outer cut surface 104, an inner cut surface 105, and a side plane 103 between the outer cut surface 104 and the inner cut surface 105; the outer arc surface 101 and / or the inner arc surface 102 face the extending direction of the braided wire 200; in the cross-section of the bamboo veneer 100, the vertical distance between the outer cut surface 104 and the inner cut surface 105 is the thickness b, and the distance between the two end points of the outer cut surface 104 is the width w; the width-thickness ratio of the bamboo veneer is (5:1) to (25:1). The mechanical properties of the bamboo veneer 100 obtained by chordal cutting are shown in Table 6 (the bamboo veneer 100 prepared by gradually chordally cutting from the outer layer to the inner layer corresponds to P1 to P8):

[0110] Table 6

[0111]

[0112] It can be seen from the data that the bamboo veneer 100 prepared by chordal cutting along the bamboo tube has a unique mechanical property gradient distribution characteristic in its wall thickness direction (from the bamboo green layer to the bamboo yellow layer), which is specifically manifested as follows: along the radial section of the bamboo, the vascular bundle density and the fiber volume fraction show a decreasing trend from the bamboo green layer to the bamboo yellow layer, resulting in a continuous gradient attenuation distribution of mechanical property indexes such as the tensile strength and elastic modulus of the material from the outer layer (bamboo green layer) to the inner layer (bamboo yellow layer). When in use, the bamboo veneer 100 close to the outer layer can be used.

[0113] Next, the technical effects of the geometric parameters of the bamboo grid are proved by experimental results:

[0114] First, a wind tunnel test is used to study the influence of the side length of the bamboo grid on sand blocking. The outer arc surface 101 and / or the inner arc surface 102 of all the bamboo veneers 100 face the same direction; the width w is 10 ± 2 mm, and the thickness b is 2 mm. The length of the bamboo veneer 100 is controlled to be 300 mm, the depth of the bamboo veneer 100 buried in the sand layer is controlled to be 50% of the length, the gap width between the bamboo veneers 100 is 10 mm, the sand particle size is between 63 and 500 μm, which is a normal distribution, and the wind speed is 15 m / s. The side length of the bamboo grid varies in the range of 300 mm to 2500 mm, and the wind resistance, ventilation rate, sand blocking and other properties of the bamboo grid are studied. The properties are shown in Table 7.

[0115] Table 7

[0116]

[0117] It can be seen from the data that when the side length of the bamboo grid increases from 300 mm to 2500 mm, the wind resistance decreases significantly with the increase of the side length, and the deflection increases synchronously; the safety factor increases linearly, indicating that the large-size structure has better structural stability; the wear depth decreases with the increase of the side length, which is related to the decrease of the impact times per unit area; the ventilation rate increases positively, indicating that a larger grid allows more air flow through; the effect of wind speed reduction decreases, which is directly related to the increase of the ventilation rate; the turbulent sedimentation efficiency decreases, reflecting the weakening of the turbulent disturbance of the large grid; the total interception rate decreases sharply with the increase of the side length, and the small-size grid has an obvious interception advantage; the dominant effect of direct interception is stronger than that of turbulent sedimentation, but both weaken with the expansion of the grid, and the reduction rate of the sand mass flux decreases synchronously; the ecological benefit improves with the increase of the size, indicating that the large grid is more conducive to the balance of the ecosystem; the burial time is significantly extended, indicating that the large-grid structure is more durable; the impact force of a single sand grain increases, but the order of magnitude of the total impact times decreases. The medium size (500-1000mm) achieves a balance between the sand blocking efficiency (75-65%) and the ecological benefit (medium - excellent).

[0118] Second, a wind tunnel test was conducted to study the influence of the change in the gap width of the bamboo strips 100 in the bamboo grid. The outer arc surface 101 and / or the inner arc surface 102 of all the bamboo strips 100 faced the same direction; the width w was 10 ± 2 mm, the thickness b was 2 mm, the length of the bamboo strips 100 was controlled to be 300 mm, the depth of the bamboo strips 100 buried in the sand layer was 50% of the length, the size of the bamboo grid was 1000 mm, the sand particle size was between 63 and 500 μm, which was a normal distribution, and the wind speed was 15 m / s. The gap width of the bamboo strips 100 varied within the range from 2 mm to 22 mm, and the wind resistance, ventilation rate, sand blocking and other performances of the bamboo grid were studied. The performances are shown in Table 8.

[0119] Table 8

[0120]

[0121] It can be seen from the data that the wind resistance decreases linearly with the increase of the gap width, and the ventilation rate increases significantly. This is because a larger gap width allows more air flow through, reducing the structural resistance, but weakening the wind speed attenuation ability. The reduction of the sand mass flux decreases from 75% to 45%, indicating that a small gap width (≤8 mm) has a better sand blocking ability. The effect of wind speed reduction decreases from 55% to 25%, which is negatively correlated with the increase of the gap width. The impact force of a single sand grain increases with the increase of the gap width, but the annual impact times per unit area decrease, resulting in a decrease in the wear depth overall.

[0122] The bamboo grid can achieve a functional gradient design from "high-strength protection" to "eco-friendly" by adjusting the gap width. A gap width of 2 - 8 mm is suitable for rapid sand fixation in areas rich in sand sources. A gap width of 12 - 16 mm is suitable for comprehensive protection in ecological restoration areas. A gap width of 20 - 22 mm is recommended for vegetation conservation in stabilized sandy lands. Dynamic optimization needs to be carried out in combination with wind speed, sand source intensity and ecological goals.

[0123] Third, a wind tunnel test was used to study the influence of the burial depth change of the bamboo strips 100 in the bamboo grid. The outer arc surface 101 and / or the inner arc surface 102 of all the bamboo strips 100 faced the same direction; the width w was controlled to be 10 ± 2 mm, the thickness b was 2 mm, the length of the bamboo strip 100 was 300 mm, the gap width of the bamboo strip 100 was 10 mm, the side length of the bamboo grid was 1000 mm, the sand particle size was between 63 - 500 μm, showing a normal distribution, and the wind speed was 15 m / s. The burial depth varied from 10% to 70% of the length, and the wind resistance, ventilation rate, sand retention and other properties of the bamboo grid were studied. The properties are shown in Table 9.

[0124] Table 9

[0125]

[0126] It can be seen from the data that: the burial depth is positively correlated with the wind resistance. When the depth increases from 10% to 70%, the wind resistance increases from 0.015 N to 0.120 N, indicating that the wind resistance of the structure is significantly enhanced. The deflection decreases from 15 mm to 1.2 mm, and the safety factor increases from 15 to 140, showing that the increase in burial depth greatly improves the anti-deformation ability of the structure. The wind speed reduction effect linearly increases from 15% to 60%. The reduction rate of the sand mass flux increases from 30% to 80%, showing that the wind protection effect is the best when the burial depth is 70%. The sand burial time is shortened from 15 months to 2 months, reflecting the positive correlation between the structure interception efficiency and the sand grain deposition speed. In summary, the burial depth of 40% - 50% is the optimal economic interval, with a total interception rate of 35% and maintaining the best ecological benefits; the wear depth is 0.8 - 1.2 mm / year, and the maintenance period is reasonable.

[0127] Fourth, a wind tunnel test was used to study the influence of the length change of the bamboo strips 100 in the bamboo grid. The outer arc surface 101 and / or the inner arc surface 102 of all the bamboo strips 100 faced the same direction; the width w was controlled to be 10 ± 2 mm, the thickness b was 2 mm, the length of the bamboo strip 100 was 300 mm, the gap width of the bamboo strip 100 was controlled to be 10 mm, the side length of the bamboo grid was 1000 mm, the burial depth was 50% of the length, the sand particle size was between 63 - 500 μm, showing a normal distribution, and the wind speed was 15 m / s. The burial depth varied from 10% to 70% of the length, and the wind resistance, ventilation rate, sand retention and other properties of the bamboo grid were studied. The properties are shown in Table 10.

[0128] Table 10

[0129]

[0130] It can be seen from the data that the wind resistance increases exponentially with the increase of length. When the length increases from 200 mm to 800 mm, the wind resistance rises from 0.040 N to 0.350 N (+775%). For long thin sheets (≥600 mm), due to the increase in the windward area, the wind load increases significantly, but the wind resistance ability weakens (the safety factor drops from 220 to 12, -94.5%). The deflection rises sharply with the increase of length: only 0.5 mm at 200 mm and up to 40 mm at 800 mm (+7900%), indicating that the long thin sheets have insufficient flexural rigidity and are prone to large deformation failure. The total interception rate reaches a peak of 45% at 400 mm (direct interception 25% + turbulent settlement 20%), and the interception efficiency decreases after the length continues to increase (only 22% at 800 mm). The impact force of a single sand grain increases from 0.007 N (200 mm) to 0.018 N (800 mm) (+157%), and the annual impact times per unit area increase from 3.0×10¹ 0 times / m² to 1.1×10¹¹ times / m² (+267%), resulting in the wear depth increasing from 0.6 mm / year to 2.7 mm / year (+350%). The sand burial time shortens from 12 months (200 mm) to 1.5 months (800 mm), reflecting that the long thin sheets accelerate sand deposition but require more frequent maintenance. The optimal interception range: a length of 400 - 500 mm, with a total interception rate of 35% - 45%, which matches with the ventilation rate of 50% - 45% to form an efficient wind-sand separation area. The wind speed reduction effect linearly increases from 18% (200 mm) to 65% (800 mm), but the sand flux reduction rate reaches 70% at 400 mm and then decreases (55% at 800 mm), indicating that although the long thin sheets reduce the wind speed, the sand grain escape intensifies.

[0131] In order to improve the ultraviolet resistance of the bamboo thin sheet 100, the surface of the bamboo thin sheet 100 is coated with an ultraviolet-resistant coating; the ultraviolet-resistant coating contains titanium dioxide, benzotriazole ultraviolet light absorber and silica sol, and the coating thickness is 50 - 100 nm.

[0132] The present invention provides a preparation method of a bamboo sand barrier, comprising the following steps:

[0133] S1. Cut the original bamboo into bamboo tubes with a length of 150 - 500 cm, and cut the bamboo tubes into a number of fan-shaped bamboo strips with equal arc lengths along the radial direction;

[0134] S2. Radially dissect the fan-shaped bamboo strips and feed them into the first group of bamboo dissecting machines. The first group consists of 1 dissecting machine, which radially dissects the arc-shaped bamboo slices into 2 bamboo slices of the same width. Feed the two bamboo slices into the second group of bamboo dissecting machines. The second group consists of 2 dissecting machines, which dissect the two bamboo slices into 4 bamboo slices of the same width. Feed the 4 bamboo slices into the third group of bamboo dissecting machines at the same time. The third group consists of 4 dissecting machines, which dissect the 4 bamboo slices into 8 bamboo slices at the same time. Feed the 8 bamboo slices into the fourth group of bamboo dissecting machines. The fourth group of dissecting machines consists of 8 dissecting machines, which dissect the 8 bamboo slices into 16 slices, and so on, until the bamboo slices are dissected into bamboo strips with a width-to-thickness ratio of (5:1) to (25:1) in a fan-shaped structure.

[0135] S3. Dry the bamboo strips until the moisture content is 8 - 30%.

[0136] S4. Arrange the bamboo strips in parallel, and use a curtain-weaving machine to form a mesh structure with warp and weft interlacing of the weaving thread and the bamboo strips, and weave the bamboo strips into one body by the insertion method or the knotting method.

[0137] Before S4 and after S3, the following steps are also included:

[0138] S5. Compound benzotriazole ultraviolet light absorber, titanium dioxide, silica-alumina sol and matrix resin in a ratio of 3:0.8:5.0:100 to form a uniform ultraviolet-resistant coating. The solid content of the silica-alumina sol is 20 - 30%, the pH value is 8 - 10, the titanium dioxide is rutile type, the particle size is 20 - 50 nm, and the matrix resin is acrylic resin or polyurethane resin.

[0139] The specific preparation process of the ultraviolet-resistant coating is as follows:

[0140] S51. Add titanium dioxide into the silica-alumina sol and ultrasonically disperse for 45 minutes.

[0141] S52. Add the benzotriazole ultraviolet light absorber into the matrix resin and stir until completely dissolved.

[0142] S53. Slowly add the titanium dioxide-silica-alumina sol dispersion obtained in S51 into the resin mixture in S52 and carry out high-speed shear stirring for 1.5 hours.

[0143] S54. Let it stand and cure for 24 hours, and filter to obtain the ultraviolet-resistant coating.

[0144] S6. Immerse the bamboo strips into the ultraviolet-resistant coating, and control the impregnation amount to be 3 - 5‰ to obtain bamboo strips coated with the ultraviolet-resistant coating.

[0145] Finally, it should be noted that the above-described embodiments are only specific embodiments of the present invention, used to illustrate the technical solutions of the present invention, rather than limiting it. The protection scope of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that any person skilled in the technical field can still modify the technical solutions described in the foregoing embodiments, or can easily think of changes, or perform equivalent replacements on some of the technical features; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered by the protection scope of the present invention.

Claims

1. A bamboo grid, characterized in that: The bamboo square is formed by connecting two L-shaped or four straight bamboo sand barriers end to end to form a square bamboo square in the shape of a square; the side length of the bamboo square is 500-1000 mm; The bamboo sand barrier is a mesh structure formed by weaving wires and bamboo sheets interlaced in warp and weft, and the bamboo sheets are arranged in parallel along the longitudinal direction; the weaving wires are perpendicular to the extending direction of the bamboo sheets, and at least one weaving wire is arranged on the bamboo sheets; The length of bamboo sheets is 200~600mm; The length-to-thickness ratio of bamboo sheets is (100:1)~(500:1); There are gaps between adjacent bamboo sheets, and the width of the gaps is 0.2 to 2.2 times the width of the bamboo sheets.

2. The bamboo grid according to claim 1, characterized in that: The buried length of the bamboo slices in the bamboo grid is 40-50% of the length of the bamboo slices.

3. The bamboo grid according to claim 1, characterized in that: The bamboo sheet is prepared by radially sectioning a bamboo tube; the cross section of the bamboo sheet is a fan ring; the side surface of the bamboo sheet is an outer curved surface, an inner curved surface, and a side plane between the outer curved surface and the inner curved surface; the outer curved surface and / or the inner curved surface face the extension direction of the braided wire; In the cross section of the bamboo sheet, the distance between the two farthest endpoints of the arc of the outer arc surface is the thickness b, and the distance between the endpoint where the side plane meets the outer arc surface and the endpoint where the side plane meets the inner arc surface is the width w; The width-to-thickness ratio of bamboo sheets is (5:1)~(25:1).

4. The bamboo grid according to claim 3, characterized in that: The thickness of the bamboo sheet is 0.8~4.0mm.

5. The bamboo grid according to claim 3, characterized in that: The outer curved surfaces and / or inner curved surfaces of all the bamboo sheets in the bamboo sand barrier are oriented in the same direction.

6. The bamboo grid according to claim 3, characterized in that: The outer curved surfaces and / or inner curved surfaces of adjacent bamboo sheets in the bamboo sand barrier face oppositely.

7. The bamboo grid according to claim 1, characterized in that: The bamboo slices are prepared by cutting the bamboo tube along the chord direction; The side surfaces of the bamboo sheet are the outer section surface, the inner section surface and the side plane between the outer section surface and the inner section surface; the outer curved surface and / or the inner curved surface face the extension direction of the braided wire; In the cross section of the bamboo sheet, the vertical distance between the outer section and the inner section is the thickness b, and the distance between the two end points of the outer section is the width w; The width-to-thickness ratio of bamboo sheets is (5:1)~(25:1).

8. The bamboo grid according to claim 1, characterized in that: The braided wire is one of hemp rope and cotton rope. When there are two braided wires, the width of the gap between the adjacent braided wires in the horizontal direction is 10~30cm.

9. The bamboo grid according to claim 1, characterized in that: The surface of the bamboo sheets is coated with a UV-protective coating; The anti-ultraviolet coating contains titanium dioxide, benzotriazole ultraviolet absorber and silica-alumina sol, and the coating thickness is 50~100nm.

10. The bamboo grid according to claim 1, characterized in that: The length of the bamboo sheet is 300~500mm.

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