Bamboo sheet and bamboo sand barrier

Abstract

The utility model discloses a bamboo sheet and a bamboo sand barrier, and belongs to the technical field of desertification control engineering. The utility model provides a bamboo sheet. The cross section of the bamboo sheet is in a sector ring shape. The width-to-thickness ratio of the bamboo sheets is (5: 1)-(25: 1); the length of each bamboo sheet ranges from 200 mm to 600 mm; and the length-to-thickness ratio of the bamboo sheets is (100: 1)-(500: 1). The utility model further provides the bamboo sand barrier which is of a warp and weft interwoven net structure and composed of the weaving lines and the bamboo sheets. The utility model further provides a preparation method of the bamboo sand barrier. According to the utility model, the structural characteristics of bamboos are utilized to manufacture the fan-ring-shaped bamboo sheets, and the bamboo sheets have elasticity, can effectively block the flow of sand grains and form a lasting sand stabilization network, and are applicable to sand stabilization materials in desertification control projects.

Description

TECHNICAL FIELD

[0001] The utility model relates to desertification prevention engineering technical field, especially a kind of bamboo sheet and bamboo sand barrier. BACKGROUND

[0002] Sand barrier is one of the key technologies of desertification prevention, and its material selection and performance optimization directly affect sand-fixing effect and ecological restoration efficiency.

[0003] The sand barrier materials commonly used in existing wind prevention and sand fixation projects mainly include biobased degradable materials. The raw materials of this type of sand barrier include natural plant materials such as crop straw (such as rice straw, wheat straw, cotton stalks, sunflower straw) and shrub branches (such as sand willow, tamarisk). This type of sand barrier has the following advantages: environmental friendliness: the material is biodegradable, which meets the requirements of ecological restoration; ground wind field regulation ability: the ground wind speed attenuation rate can reach 50-70%. However, the raw materials of this type of sand barrier have the following disadvantages: poor aging resistance (service life ≤ 2 years), low mechanical strength (bending strength ≤ 3 MPa), and low industrial production adaptability. In addition, sand barrier materials also include synthetic polymer materials, such as polyolefin plastics (such as PE, PP) or polylactic acid (PLA) as the main material. The advantages of this type of sand barrier are: structural stability: wind erosion resistance ≥ 5 years, tensile strength ≥ 20 MPa. However, synthetic polymer materials also have limitations: the natural degradation period of traditional plastic-based materials is more than 50 years, which poses a risk of microplastic pollution; the cost of PLA material is 200-300% higher than that of traditional plastic.

[0004] In addition, in traditional wind prevention and sand fixation projects, the sand barrier structure usually uses a rod body with a circular cross section as a basic unit, and forms a wind-blocking barrier through arrayed arrangement. However, this type of design has significant defects in aerodynamic characteristics: when air flows through a circular single rod, the laminar boundary layer easily flows smoothly along the surface of the rod, forming a symmetrical flow separation point, which leads to insufficient turbulence vortex intensity in the rear wake area. Under this mechanism, the wind field energy is limited, and the sand particle transport kinetic energy is not fully dissipated, resulting in low overall wind protection efficiency of the sand barrier group. To make up for the insufficient protection efficiency of single sand barrier, the existing technology usually adopts a dense arrangement strategy, which significantly increases the project cost. In addition, high-density sand barriers can form a continuous rigid interface, which can even exacerbate local wind erosion risk, especially in the gap area between sand barriers, which may cause secondary sand raising due to the narrow tube effect. UTILITY MODEL CONTENTS

[0005] Therefore, the utility model provides a bamboo sheet and a bamboo sand barrier, which have high strength, good toughness and can be mass-produced mechanically.

[0006] In the first aspect, the utility model provides a bamboo sheet, which is prepared by cutting a bamboo cylinder along the radial direction;

[0007] The cross section of the bamboo sheet is a fan ring shape; the side surface of the bamboo sheet is an outer arc surface, an inner arc surface, and a side plane between the outer arc surface and the inner arc surface;

[0008] In the cross section of the bamboo sheet, the distance between the two most distant end points of the circular arc of the outer arc surface is the thickness b, and the distance between the end point where the side plane meets the outer arc surface and the end point where the side plane meets the inner arc surface is the width w.

[0009] The width-thickness ratio of the bamboo sheet is (5:1) to (25:1).

[0010] The distance from one end to the other end of the extension direction of the bamboo sheet is the length.

[0011] The length of the bamboo sheet is 200 to 600 mm.

[0012] The length-thickness ratio of the bamboo sheet is (100:1) to (500:1).

[0013] According to the bamboo sheet described above, the thickness of the bamboo sheet is 0.8 to 4.0 mm.

[0014] Preferably, the length-thickness ratio of the bamboo sheet is (270:1) to (330:1).

[0015] According to the bamboo sheet described above, the surface of the bamboo sheet is coated with an ultraviolet-proof coating layer; the thickness of the coating layer is 50 to 100 nm.

[0016] In a second aspect, the utility model provides a bamboo sand barrier, the bamboo sand barrier comprises a weaving line and the bamboo sheet of the first aspect and is composed of a net-like structure which is interwoven in warp and weft, and the bamboo sheet is arranged in parallel along the longitudinal direction; the weaving line is arranged perpendicularly to the extension direction of the bamboo sheet, and the weaving line is arranged on the bamboo sheet in at least one row.

[0017] The outer arc surface and / or the inner arc surface faces the extension direction of the weaving line.

[0018] There is a gap between the adjacent bamboo sheets, and the width of the gap is 0.2 to 2.2 times the width w of the bamboo sheet.

[0019] According to the bamboo sand barrier described above, the outer arc surfaces and / or the inner arc surfaces of all the bamboo sheets face the same direction.

[0020] According to the bamboo sand barrier described above, the outer arc surfaces and / or the inner arc surfaces of the adjacent bamboo sheets face opposite directions.

[0021] According to the bamboo sand barrier described above, the weaving line is one of a hemp rope and a cotton rope, and when the weaving line is two rows, the width of the gap between the transversely adjacent weaving lines is 10 to 30 cm.

[0022] Compared with the prior art, the utility model has the following beneficial effects:

[0023] (1) The utility model discloses a bamboo sheet, which is prepared by precisely controlling the geometric parameter range of the bamboo sheet, so that the bamboo sheet has optimal elastic deformation capacity while maintaining the bending strength of natural bamboo. On the one hand, the bamboo sheet is more likely to bend than break under strong wind, which can disperse wind pressure and prolong the service life, thereby maintaining the integrity of the sand-fixing structure for a long time. On the other hand, the elastic bamboo sheet will produce slight vibration in the wind, which can further weaken the near-surface wind speed through turbulent disturbance and reduce the sand particle initiation. In addition, when the bamboo sheet is implanted into the sand layer in a specific arrangement, the unique fan ring cross-sectional morphology and elastic mechanical properties can effectively block the flow of sand particles and form a durable sand-fixing network, which is suitable for the application of sand-fixing materials in desertification control projects.

[0024] (2) The bamboo sand barrier prepared from the fan ring-shaped bamboo sheet has good windproof and sand-fixing effects. Compared with the bamboo sheet with a rectangular structure, the inclined windward surface of the fan ring-shaped bamboo sheet guides the airflow to deflect smoothly, so that the sand particles slide along the surface and reduce accumulation. The rebound angle of the sand particles colliding with the fan ring-shaped bamboo sheet is smaller.

[0025] (3) When the outer arc surface and / or the inner arc surface of the adjacent bamboo sheets face opposite directions, a horn mouth of the fan ring-shaped bamboo sheet is formed, the maximum gap velocity of the bamboo sand barrier is only 8.4 m / s, the horn mouth inhibits airflow acceleration, and the downstream wind speed is stable; the coarse sand is naturally deposited, and the maintenance cost is low. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a schematic diagram of the three-dimensional structure of the bamboo sheet of the utility model;

[0027] Figure 2 It is a transverse sectional view of the bamboo sheet of the utility model;

[0028] Figure 3 It is a schematic diagram of the three-dimensional structure of a bamboo sand barrier of the utility model;

[0029] Figure 4 It is a schematic diagram of the three-dimensional structure of another bamboo sand barrier of the utility model.

[0030] Explanation of reference signs:

[0031] 100, bamboo sheet; 101, outer arc surface; 102, inner arc surface; 103, side plane;

[0032] 200, braided wire. DETAILED DESCRIPTION

[0033] To make the technical problems, technical solutions and advantages of the utility model clearer, the technical solutions of the utility model will be described clearly and completely in combination with the drawings and specific embodiments. Figures 1 to 4 and specific embodiments.

[0034] A first aspect of the present invention provides a bamboo sheet, prepared by radially slicing a bamboo tube; as shown in the example... Figure 1 and Figure 2 As shown, the cross-section of the bamboo sheet is fan-shaped; the side surface of the bamboo sheet 100 consists of 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 sheet 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 of the side plane 103 that connects with the outer arc surface 101 and the endpoint of the side plane 103 that connects with the inner arc surface 102 is the width w; the width-to-thickness ratio of the bamboo sheet 100 is (5:1) to (25:1); the distance from one end to the other in the extension direction of the bamboo sheet 100 is the length; the length of the bamboo sheet 100 is 200 to 600 mm; and the length-to-thickness ratio of the bamboo sheet is (100:1) to (500:1). To ensure the strength of the bamboo sheet 100 while avoiding waste of bamboo, the width-to-thickness ratio and length-to-thickness ratio of the bamboo sheet 100 are preferred conditions.

[0035] The following provides an example 1 of the present invention: a sand barrier grid formed by bamboo sheet 100, and a comparative example 1: a sand barrier grid formed by straw.

[0036] Among them, the modulus of elasticity and bending strength were tested in accordance with the "Test Methods for Physical and Mechanical Properties of Bamboo (GB / T 15780-1995)", and the maximum bending moment and bending stress were tested using the uniaxial cantilever beam bending stress test method.

[0037] Example 1: A sand barrier grid is formed using bamboo sheets 100. The bamboo sheets 100 are dried to a moisture content of 8-30%. Two weaving lines 200 are set on the bamboo sheets 100. The weaving lines 200 are cotton ropes with a diameter of 2mm. The bamboo sheets 100 are woven into a bamboo sand barrier curtain. The outer arc surface 101 and / or the inner arc surface 102 face the extension direction of the weaving lines 200. The outer arc surface 101 and / or the inner arc surface 102 of all bamboo sheets 100 face the same direction. The length of the bamboo sheet 100 is 500mm, the width w is 10±2mm, the thickness b is 2mm, the distance between two adjacent bamboo sheets 100 is 5±2mm, the size of the sand barrier grid is 100cm×100cm, the length of the bamboo sheet 100 inserted into the sand layer is 25±3cm, and the length of the bamboo sheet 100 exposed in the sand layer is 25±3cm.

[0038] Comparative Example 1:

[0039] The straw is used to form a sand barrier square, wherein the diameter of the straw is 5±2 mm, the straw is cut into a length of 50 cm, the straw is woven into a straw curtain by using a cotton rope with a diameter of 2 mm, the gap width between the straws is 5±2 mm, and the straw curtain is inserted into the ground. The size of the straw square is 100*100 cm.

[0040] The basic mechanical properties of the bamboo sheet and the straw are shown in Table 1:

[0041] Table 1

[0042]

[0043] The initial interception efficiency of the straw square of the comparative example 1 is 65~70%, but the gap is closed due to serious bending, and the structure is completely disabled after being broken. The wind permeability of the bamboo square made of the bamboo sheet of the example 1 is reduced to 26.7%, the turbulence is increased by 15~20%, and the interception efficiency reaches 90~100%. The bamboo sheet of the example 1 has higher rigidity and anti-deformation ability, can effectively resist the impact of wind sand and sand layer pressure, and avoid structural damage. The insertion depth of the bamboo into the sand layer (25±3 cm) is equal to the length of the exposed part, forming a symmetrical support system, and the anti-overturning ability is stronger; the straw is soft in material and is easy to tilt or displace after being inserted. Through the high mechanical properties, precise structure design and environmental adaptability of the bamboo sheet, the problems of easy deformation, wind permeability failure and poor durability of the straw sand barrier are solved, and the efficient, stable and sustainable sand fixation effect is realized. The high mechanical properties and safety factor of the bamboo sand barrier can significantly prolong the service life and reduce the maintenance frequency; the straw sand barrier needs to be frequently rebuilt due to rapid failure, and the comprehensive cost is higher. In addition, the bamboo is a renewable resource, and the processing process is low-carbon and environmentally friendly, which is highly consistent with the ecological goal of desertification control.

[0044] The sand blocking effect of the bamboo sheet and the straw is shown in Table 2:

[0045] Table 2

[0046]

[0047] The interception efficiency of the straw square is disabled, the structure stability is low, and the interception efficiency is 90~100%. The applicable scene is short-term emergency, low wind speed area (<8 m / s) long-term engineering, and strong wind sand area (>10 m / s). Compared with the straw, the bamboo sheet has good sand blocking effect.

[0048] Next, the technical effect of the geometric parameters of the bamboo sheet 100 is proved by experimental results:

[0049] The width-to-thickness ratio of the bamboo sheet 100 is controlled to be constant (in the experiment, the width-to-thickness ratio is controlled to be 8), and the length-to-thickness ratio is changed. Six examples and one comparative example are used in the experiment. The length of the bamboo sheet 100 is constant, which is 600 mm. The outer arc surface 101 and / or the inner arc surface 102 of all the bamboo sheets 100 are consistent. The specific parameters (thickness, width, and length) are set as shown in Table 3. The performance of the bamboo sheet 100 applied to the sand barrier is studied by using a wind tunnel test at a wind speed of 20 m / s, and the spacing of the bamboo sheet 100 is 40% of the width of the bamboo sheet. The length of the bamboo sheet 100 inserted into the sand layer is 300±30 mm, and the length of the bamboo sheet 100 exposed to the sand layer is 300±30 mm. The bending stress, deflection, and sand blocking efficiency of the bamboo sheet 100 are shown in Table 3.

[0050] Material parameters: elastic modulus E = 12.5 GPa, tensile strength σ b = 128 MPa;

[0051] Environmental parameters: wind speed v = 20 m / s, air density p = 1.225 kg / m³;

[0052] Calculation formula:

[0053] Transmittance: η = [s / (s+b)]²;

[0054] Wherein, s is the gap width between adjacent bamboo sheets, and b is the width of the bamboo sheet.

[0055] Wind load: F = 0.5 p v²C d ·(L·b);

[0056] Wherein, C d is the drag coefficient; L is the length of the bamboo sheet exposed to the sand layer, i.e., the distance from the surface of the sand layer to the top end, which is half of the length of the bamboo sheet, which is 300 mm.

[0057] Bending stress: σ = 6FL / (bw²);

[0058] Deflection: δ = 4FL³ / (Ebw³);

[0059] Safety factor: n = σ b / σ;

[0060] Sand blocking efficiency: E 阻 = η(1-η)(1-δ / 300).

[0061] Table 3

[0062]

[0063] Example 3 meets the safety requirement, but the sand blocking efficiency is significantly lower than the thicker examples, and the cost and performance requirements need to be balanced. Example 2 has a safety factor of 23.2 and a sand blocking efficiency of 0.070, and the structure is critically safe, suitable for low-risk environments. Examples 4-6 (thickness 1.8-2.2 mm, length-thickness ratio 270-330) have the best overall performance: safety factor far exceeds the safety threshold (>10); sand blocking efficiency close to the theoretical peak; material efficiency: moderate thickness, avoiding redundancy. Bamboo sheet sand barriers in the range of (length-thickness ratio 270-330) have high wind resistance, high sand blocking efficiency, and reasonable cost, 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 sand blocking efficiency cannot be calculated according to the formula, the structure fails. The thickness of Example 7 is too large, the safety factor is too high, far exceeding the requirements ("excess"), and the material redundancy significantly increases the cost, which is not economical in engineering. The failure of Comparative Example 2 and the excess of Example 7 warn that design parameters need to be strictly controlled, and dynamic optimization should be combined with actual wind and sand conditions.

[0064] The effect of the length-thickness ratio and the width-thickness ratio of the bamboo sheet 100 on the performance of the bamboo sheet 100 applied to the sand barrier was studied. In the experiment, five examples and two comparative examples were used. The width of the bamboo sheet 100 was constant, and the width was 20 mm. The outer arc surface 101 and / or the inner arc surface 102 of all bamboo sheets 100 were oriented in the same direction. The specific parameters (thickness, width, and length) were set as shown in Table 4. The wind speed was 20 m / s, the spacing of the bamboo sheet 100 was 40% of the width of the bamboo sheet 100, the length of the bamboo sheet 100 inserted into the sand layer was 1 / 2 of the length of the bamboo sheet 100, and the length of the bamboo sheet 100 exposed to the sand layer was 1 / 2 of the length of the bamboo sheet 100. The performance of the bamboo sheet 100 applied to the sand barrier was studied using a wind tunnel test, and the performance (bending stress, deflection, safety factor, sand blocking efficiency) was also shown in Table 4:

[0065] Table 4

[0066]

[0067] The width-thickness ratio and the length-thickness ratio together determine the wind resistance of the bamboo sheet: as the width-thickness ratio decreases (thickness increases) and the length-thickness ratio decreases (thickness increases or length decreases), the bending stress decreases significantly.

[0068] Example 8-9 (width-thickness ratio 20~25, thickness 0.8~1.0 mm): safety factor 23.2 (critical safety), suitable for low-risk environment; Example 12 (width-thickness ratio 5, thickness 4.0 mm): safety factor 256.0, sand-blocking efficiency 0.086, but higher material cost. Examples 10-11 (width-thickness ratio 10~12.5, thickness 1.6~2.0 mm, length-thickness ratio 300~375): best overall performance: safety far beyond the safety threshold (>10); sand-blocking efficiency: 0.083~0.085, close to the theoretical peak value; material efficiency: moderate thickness, avoiding redundancy. The excess of Comparative Example 3 and the failure of Comparative Example 4 warn that the width-thickness ratio and the length-thickness ratio need to be strictly controlled in the collaborative design, and dynamically optimized in combination with the actual wind and sand conditions.

[0069] The bamboo sheet sand barrier reaches the best balance among safety (safety factor >40), sand-blocking efficiency (0.083~0.085), and material economy in the width-thickness ratio (10:1)~(12.5:1) range, has high wind resistance, high-efficiency sand-blocking efficiency, and reasonable cost, and is suitable for desertification control engineering.

[0070] The present application precisely controls the geometric parameter range of the bamboo sheet 100, so that the bamboo sheet 100 maintains the natural bamboo bending strength while obtaining the optimal elastic deformation capacity. On the one hand, under the action of strong wind, the bamboo sheet 100 is more likely to bend than to break, can disperse wind pressure, prolong service life, and long-term maintain the integrity of the sand-fixing structure; on the other hand, the elastic bamboo sheet 100 will produce slight vibration in the wind, which can further weaken the near-surface wind speed through turbulent disturbance and reduce the sand particle starting. In addition, when the bamboo sheet 100 is implanted in the sand layer in a specific arrangement manner, the unique fan ring cross-sectional morphology and elastic mechanical properties synergistically act to effectively block the flow of sand particles, form a persistent sand-fixing network, and are suitable for sand-fixing material applications in desertification control engineering.

[0071] The bamboo sheet 100 has, from the outer ring to the inner ring, a bamboo green layer, a bamboo flesh layer, and a bamboo yellow layer; the density of the bamboo flesh layer gradually changes from the bamboo green layer to the bamboo yellow layer, and the density near the bamboo green layer is 0.85~1.0 g / cm³, and the density near the bamboo yellow layer is 0.45~0.65 g / cm³. The density gradient feature makes the bamboo sheet preferentially bear the compressive stress in the high-density area of the outer ring when loaded, and the low-density area in the inner ring absorbs energy through elastic deformation, forming a synergistic impact resistance mechanism similar to a "rigid-soft composite layer", which can increase the bending fatigue life by about 50% compared with homogeneous materials.

[0072] In order to improve the ultraviolet resistance of the bamboo sheet, the surface of the bamboo sheet is coated with a layer of ultraviolet-resistant coating; the ultraviolet-resistant coating comprises titanium dioxide, a benzotriazole ultraviolet light absorber, and a silicon-aluminum sol, and the coating thickness is 50~100 nm.

[0073] A second aspect of the present invention provides a bamboo sand barrier, comprising a weft-woven mesh structure composed of woven threads 200 and bamboo sheets 100 as described in the first aspect, wherein the bamboo sheets 100 are arranged in parallel along the longitudinal direction; the woven threads 200 extend perpendicularly to the extension direction of the bamboo sheets 100, and at least one woven thread 200 is provided on the bamboo sheets 100; the outer arc surface 101 and / or the inner arc surface 102 face the extension direction of the woven threads 200; there is a gap between adjacent bamboo sheets 100, the gap width being 0.2 to 2.2 times the width w of the bamboo sheet 100.

[0074] Furthermore, the braided thread is either hemp rope or cotton rope, and the gap between adjacent braided threads is 10~30cm, which can form a stable connection structure for the bamboo sand barrier.

[0075] The following is an example 2, which describes a sand barrier grid formed by a fan-shaped bamboo sheet 100, and a comparative example 2, which describes a sand barrier grid formed by a rectangular bamboo sheet.

[0076] Example 13:

[0077] The fan-shaped bamboo sheet 100 has a width of 12mm and a thickness of 2mm. The gap between adjacent bamboo sheets 100 is 6mm. The outer arc surface 101 and / or the inner arc surface 102 face the extension direction of the braided thread 200. The outer arc surface 101 and / or the inner arc surface 102 of all bamboo sheets 100 face the same direction. Figure 3 As shown. All bamboo sheets 100 are perpendicular to the ground, with the thickness direction being laterally oriented, and the side plane 103 is the windward side. A wind tunnel test was conducted with an ambient wind speed of 10 m / s.

[0078] Comparative Example 5:

[0079] The rectangular bamboo strips are 12mm wide and 2mm thick, with right angles at the edges; the gap between adjacent rectangular bamboo strips is 6mm. The width direction of the rectangular bamboo strips is the windward side. A wind tunnel test was conducted with an ambient wind speed of 10 m / s.

[0080] The properties of fan-shaped and rectangular bamboo strips are shown in Table 5:

[0081] Table 5

[0082]

[0083] The side plane of the fan ring-shaped bamboo sheet deflects the airflow gently, forming low turbulence; the right-angle edge of the rectangular bamboo sheet causes airflow to separate violently, forming strong turbulence and recirculation zone, which is prone to cause local erosion. The inclined surface of the fan ring-shaped bamboo sheet causes the rebound speed of sand particles after collision to be <1 m / s, and the saltation distance to be reduced by 30%, and the sand particles slide along the surface to avoid accumulation on the windward side; the right-angle edge of the rectangular bamboo sheet directly intercepts sand particles, and the rebound wind speed reaches 3-5 m / s, and the sand particles are prone to form a "sand dam" on the windward side, changing the wind permeability and causing local wind erosion. The fan ring-shaped bamboo sheet sand barrier of Example 13 solves the problems of rapid increase of turbulence, rebound accumulation of sand particles and structural failure caused by the right-angle edge of the rectangular bamboo sheet through aerodynamic shape optimization. The design is significantly superior to the traditional rectangular sand barrier in terms of sand fixation efficiency, environmental adaptability and maintenance cost, and provides an efficient and low-cost engineering solution for desertification control.

[0084] Example 14:

[0085] The width of the fan ring-shaped bamboo sheet 100 is 12 mm, the thickness is 2 mm, the gap width between adjacent bamboo sheets 100 is 6 mm, and the outer arc surface 101 and / or the inner arc surface 102 of the adjacent bamboo sheet 100 extending towards the extension direction of the weaving line 200 faces the opposite outer arc surface 101 and / or the inner arc surface 102, and the outer arc surface 101 faces outward and the inner arc surface 102 forms a "bell mouth" shape, as shown in Figure 4 Specifically, the width at the inlet is 6 mm, and the width at the outlet is 5.83 mm. All bamboo sheets 100 are perpendicular to the ground, the thickness direction is lateral, and the side plane 103 is the windward surface. A wind tunnel test is used, and the environmental wind speed is 10 m / s.

[0086] Comparative Example 6:

[0087] The width of the rectangular bamboo sheet is 12 mm, the thickness is 2 mm, and the edge is a right angle; the gap width between adjacent rectangular bamboo sheets is 6 mm. The width direction surface of the rectangular bamboo sheet is the windward surface. A wind tunnel test is used, and the environmental wind speed is 10 m / s.

[0088] The performance of the fan ring-shaped bamboo sheet and the rectangular bamboo sheet is shown in Table 6:

[0089] Table 6

[0090]

[0091] The maximum gap flow velocity of the bell mouth of the fan ring-shaped bamboo sheet is only 8.4 m / s (16% lower than the straight channel), and the bell mouth suppresses airflow acceleration, and the downstream wind speed is stable; coarse sand naturally deposits, and the maintenance cost is low.

[0092] The influence of gap width variation of bamboo sheet 100 is studied by wind tunnel test, all the outer arc surface 101 and / or inner arc surface 102 of the bamboo sheet 100 are consistent; the width w is 10±2mm, the thickness b is 2mm, the length of the bamboo sheet 100 is controlled to be 300mm, the depth of the bamboo sheet 100 buried in the sand layer is 50% of the length, the sand particle size is between 63-500μm, which is a normal distribution, and the wind speed is 15m / s. The gap width of the bamboo sheet 100 varies from 2mm to 22mm, the wind resistance, wind permeability, sand resistance and other performances are studied, and the performances are shown in Table 7.

[0093] Table 7

[0094]

[0095] From the data, it can be seen that the wind resistance decreases linearly with the increase of gap width, and the wind permeability is significantly improved, because the larger gap width allows more airflow to pass through, reduces the structural resistance, but weakens the wind speed attenuation ability. The sand mass flux decreases from 75% to 45%, which shows that small gap width (≤8mm) has better sand resistance ability. The wind speed reduction effect decreases from 55% to 25%, which is negatively correlated with the expansion of the gap width. The impact force of single sand particle increases with the increase of gap width, but the impact times per unit area per year decreases, which comprehensively leads to the decrease of wear depth.

[0096] The bamboo square grid can realize the functional gradient design from "high strength protection" to "ecological friendly type" by adjusting the gap width. The gap width of 2-8mm is suitable for rapid sand fixation in sand source rich area, the gap width of 12-16mm is suitable for comprehensive protection in ecological restoration area, and the gap width of 20-22mm is recommended for vegetation conservation in stable sand land. It needs to be dynamically optimized in combination with wind speed, sand source intensity and ecological target.

[0097] The utility model discloses a preparation method of bamboo sand barrier, comprising the following steps:

[0098] S1, the length of the original bamboo is cut to 150-500cm bamboo cylinder, and the bamboo cylinder is divided into a plurality of fan ring bamboo strips with equal arc length along the radial direction;

[0099] S2, the fan ring bamboo strip is radially split and sent to a first set of bamboo splitting machines, the first set of splitting machines is composed of one bamboo splitting machine, the arc-shaped bamboo piece is radially or chordally split into two pieces of the same width; the two pieces of bamboo are sent to a second set of bamboo splitting machines, the second set of splitting machines is composed of two bamboo splitting machines, the two pieces of bamboo are split into four pieces of the same width; the four pieces of bamboo are simultaneously sent to a third set of bamboo splitting machines, the third set of splitting machines is composed of four bamboo splitting machines, the four pieces of bamboo are simultaneously split into eight pieces of bamboo; the eight pieces of bamboo are sent to a fourth set of bamboo splitting machines, the fourth set of splitting machines is composed of eight bamboo splitting machines, the eight pieces of bamboo are split into sixteen pieces, and the like, until the bamboo pieces are split into bamboo sheet 100 in a fan ring structure with a width-thickness ratio of (5:1)~(25:1);

[0100] S3, the bamboo sheet 100 is dried to a moisture content of 8~30%.

[0101] S4, the bamboo sheet 100 is arranged in parallel, a weaving machine is used to weave the weaving line 200 and the bamboo sheet 100 into a mesh structure, and the bamboo sheet 100 is woven into an integrated body by insertion or knotting.

[0102] In addition, when an ultraviolet-proof coating is added to the surface of the bamboo sheet 100, the following steps are further included after S3 and before S4:

[0103] S5, a benzotriazole ultraviolet light absorber, titanium dioxide, silicon-aluminum sol and a base resin are compounded in a ratio of 3:0.8:5.0:100 to form a uniform ultraviolet-proof coating, the silicon-aluminum sol has a solid content of 20~30% and a pH value of 8~10, the titanium dioxide is rutile type with a particle size of 20~50 nm, and the base resin is an acrylic resin or a polyurethane resin;

[0104] S6, the bamboo sheet is immersed in the ultraviolet-proof coating, and the immersion amount is controlled to be 3~5‰, to obtain the bamboo sheet 100 coated with the ultraviolet-proof coating.

[0105] The specific preparation process of the ultraviolet-proof coating is as follows:

[0106] S51, the titanium dioxide is added to the silicon-aluminum sol and ultrasonically dispersed for 45 minutes;

[0107] S52, the benzotriazole ultraviolet light absorber is added to the base resin and stirred until completely dissolved;

[0108] S53, the titanium dioxide-silicon-aluminum sol dispersion liquid obtained in S51 is slowly added to the resin mixture in S52, and high-speed shearing stirring is performed for 1.5 hours;

[0109] S54, standing and curing for 24 hours, and then filtering to obtain the ultraviolet-proof coating.

[0110] Finally, it should be noted that the above-described embodiments, only for the specific embodiments of the present application, in order to illustrate the technical solutions of the present application, rather than limit it, the scope of protection of the present application is not limited to this, although the foregoing detailed description of the present application, the ordinary skill in the art should be understood: any skilled in the art in the technical field disclosed by the present application, the technical range, it still can be modified or easily thought of changes to the technical solutions recorded in the foregoing examples, or part of the technical features of the equivalent replacement; and these modifications, changes or replacement, and do not make the corresponding technical solutions of the essence of the present application embodiments technical solutions out of the spirit and scope, all should be covered in the scope of protection of the present application.

Claims

1. A bamboo sheet (100) characterized in that, The bamboo tube is radially cut to obtain the bamboo sheet; The cross section of the bamboo sheet (100) is a fan ring; the side surface of the bamboo sheet (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 sheet (100), the distance between the two farthest endpoints of the circular arc of the outer arc surface (101) is the thickness b, and the distance between the endpoint of the side plane (103) connected with the outer arc surface (101) and the endpoint of the side plane (103) connected with the inner arc surface (102) is the width w; The width-thickness ratio of the bamboo sheet (100) is (5:1) to (25:1); The length of the bamboo sheet (100) is the distance from one end to the other end in the extension direction; The length of the bamboo sheet (100) is 200 to 600 mm; The length-thickness ratio of the bamboo sheet is (100:1) to (500:1).

2. The bamboo sheet (100) according to claim 1, characterized in that, The thickness of the bamboo sheet (100) is 0.8 to 4.0 mm.

3. The bamboo sheet (100) according to claim 1, characterized in that, The length-thickness ratio of the bamboo sheet is (270:1) to (330:1).

4. The bamboo sheet (100) according to claim 1, characterized in that, The surface of the bamboo sheet (100) is coated with an ultraviolet-proof coating layer, and the thickness of the coating layer is 50 to 100 nm.

5. A bamboo fence, characterized in that, The bamboo sand barrier comprises woven threads (200) and the bamboo sheet (100) according to any one of claims 1 to 4, and the bamboo sheet (100) is arranged in a longitudinal parallel manner; the woven threads (200) are arranged in a direction perpendicular to the extension direction of the bamboo sheet (100), and the woven threads (200) are arranged on the bamboo sheet (100) in at least one row; The outer arc surface (101) and / or the inner arc surface (102) are arranged in the extension direction of the woven threads (200); The adjacent bamboo sheets (100) have gaps therebetween, and the width of the gaps is 0.2 to 2.2 times the width w of the bamboo sheet (100).

6. The bamboo fence according to claim 5, wherein, The outer arc surfaces (101) and / or the inner arc surfaces (102) of all the bamboo sheets (100) are arranged in the same direction.

7. The bamboo fence according to claim 5, wherein, The outer arc surfaces (101) and / or the inner arc surfaces (102) of the adjacent bamboo sheets (100) are arranged in opposite directions.

8. The bamboo fence according to claim 5, wherein, The woven threads (200) are one of a hemp rope and a cotton rope, and when the woven threads (200) are arranged in two rows, the width of the gap between the transversely adjacent woven threads (200) is 10 to 30 cm.

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