A method of manufacturing a geomembrane

Abstract

The application discloses a single-track extrusion welding process of geomembrane, comprising the following steps: carrying out flattening treatment and drying treatment on a bottom surface of a reservoir; cutting the geomembrane into a suitable size and laying the geomembrane on the bottom surface of the reservoir, so that a lap joint area is kept in a flat state; sequentially staggered lap joining TPO geomembrane, geomembrane and HDPE geomembrane, and welding through a single-track extrusion welding machine, so that a joint between the geomembrane blocks is in a T shape; testing the geomembrane, marking and repairing a defect position found until retesting is qualified; wherein the geomembrane comprises a base material layer and an ultraviolet resistant layer coated on an upper surface of the base material layer, and a thickness ratio of the base material layer to the ultraviolet resistant layer is 1: (0.1-0.5). The geomembrane is convenient to construct, has excellent deformation adaptability of an elastic material and weldability of a plastic material, and can avoid leakage damage of a connection part of a reservoir bottom when used for reservoir permeation control.

Description

Technical Field

[0001] This application relates to a single-track extrusion welding process for geomembranes, belonging to the field of geomembrane construction technology. Background Technology

[0002] Seepage prevention construction in reservoir areas is a crucial step in water conservancy, environmental protection, and construction engineering. Its purpose is to prevent water, chemicals, or pollutants from seeping into the soil, thereby protecting groundwater resources and the surrounding environment. In this field, geomembrane construction technology has become an important and indispensable engineering practice due to its outstanding seepage prevention effect, long-term stability, and economic efficiency.

[0003] High-density polyethylene (HDPE) geomembranes have advantages such as good durability, large width, fast construction speed, and low project cost. However, engineering practice has found that HDPE geomembranes with a thickness of 1.0 mm or more have excessive hardness, which reduces their ability to adapt to foundation deformation. Due to the large differential displacement at the anchoring points with the structure, they are prone to tensile failure, which can lead to concentrated leakage in reservoirs. Summary of the Invention

[0004] To address the aforementioned issues, a single-track extrusion welding process for geomembranes is provided, which is convenient to construct. The geomembrane used combines the excellent deformation adaptability of elastic materials with the weldability of plastic materials, thus preventing leakage and damage at the bottom connection points when used for reservoir seepage control.

[0005] The present invention adopts the following technical solution:

[0006] A monorail extrusion welding process for geomembranes includes:

[0007] (1) The surface of the bottom of the silo is leveled to ensure that there are no impurities within a vertical depth of 20-25mm, and then the surface of the bottom of the silo is dried to ensure that the moisture content of the bottom of the silo does not exceed 15%;

[0008] (2) Based on the condition of the reservoir bottom, cut the geomembrane to a suitable size, then lay the stretched geomembrane on the surface of the reservoir bottom, and keep the overlapping area flat.

[0009] (3) TPO geomembrane, geomembrane and HDPE geomembrane are overlapped in sequence with staggered joints and welded by a single rail extrusion welding machine so that the intersection of the membrane blocks is T-shaped;

[0010] (4) Test the TPO geomembrane, geomembrane and HDPE geomembrane welded together in step (3), and mark and repair the defective parts until the retest is qualified;

[0011] The geomembrane includes a substrate layer and an anti-ultraviolet layer coated on the upper surface of the substrate layer, wherein the thickness ratio of the substrate layer to the anti-ultraviolet layer is 1:(0.1-0.5).

[0012] Optionally, in step (3), the welding temperature is 350-420℃ and the welding speed is 2-3m / min.

[0013] Optionally, in step (3), the overlap width is 10-12cm.

[0014] Optionally, the thickness ratio of the TPO geomembrane, the geomembrane and the HDPE geomembrane is (1-1.8):1:(1-1.5).

[0015] Optionally, the geomembrane is prepared by the following method:

[0016] a. By weight, 15-20 parts of polyetheretherketone, 10-16 parts of polycarbonate, 8-13 parts of modified polyester fiber, 6-11 parts of boron nitride, 30-45 parts of high-density polyethylene, 25-32 parts of low-density polyethylene, 20-27 parts of linear low-density polyethylene, 15-25 parts of polyethylene and 12-18 parts of ethylene-octene copolymer are placed into a twin-screw extruder. The main extruder speed is 50-60 rpm. After extrusion through the die at 170-180℃, the material is calendered to obtain the substrate layer.

[0017] b. Disperse nano-SiO2 in a mixed solution of distilled water and anhydrous ethanol, then add 3-7% silane coupling agent and stir until homogeneous to obtain an aqueous solution of nano-SiO2. Dissolve polyvinyl alcohol in distilled water to obtain an aqueous solution of polyvinyl alcohol. Mix the aqueous solution of polyvinyl alcohol and the aqueous solution of nano-SiO2 and place them in a water bath and stir for 20-40 minutes. Then place them in an ultrasonic water bath and ultrasonically disperse for 20-40 minutes. After filtration, the anti-ultraviolet coating layer is obtained.

[0018] c. Apply the UV-resistant coating to the upper surface of the substrate layer, and after drying, form a UV-resistant layer to obtain a geomembrane.

[0019] Optionally, in step b, the weight ratio of nano-SiO2 to polyvinyl alcohol is (0.5-1.2):10.

[0020] Optionally, in step c, the coating amount of the UV-resistant layer on the upper surface of the substrate layer is 180-250 g / m². 2 .

[0021] Optionally, in step a, the method for preparing the modified polyester fiber includes the following steps:

[0022] S1. Soak polyester fibers in anhydrous ethanol overnight, remove and dry them to obtain pretreated polyester fibers;

[0023] S2. Add dopamine hydrochloride to Tris buffer and stir until homogeneous to prepare a dopamine solution with a concentration of 1-3 g / L. Then, soak the pretreated polyester fiber in the dopamine solution overnight, take it out, wash it with water, and dry it to obtain the preliminarily modified polyester fiber.

[0024] S3. Mix silane coupling agent and ethanol at a volume ratio of 1:(400-600) at 40-60℃ for 1-3 hours, then add FeCl3 and disperse evenly. Then add the preliminarily modified polyester fiber and soak for 1-3 hours. After washing and drying, the modified polyester fiber is obtained.

[0025] Optionally, the silane coupling agent is selected from at least one of KH550, KH560, and KH570.

[0026] Optionally, in step S3, the weight of the silane coupling agent is 8-12% of the initially modified polyester fiber.

[0027] In this application, "TPO" refers to 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0028] The beneficial effects of this application include, but are not limited to:

[0029] 1. The monorail extrusion welding process for the geomembrane of this application, through leveling and drying the surface of the reservoir bottom, ensures that there are no uneven or sharp objects in the construction area, avoiding damage to the geomembrane and maintaining stable performance of the geomembrane during use; based on the soil type, thickness, particle distribution, and groundwater level of the reservoir bottom, appropriate geomembrane materials are selected during construction to ensure that they can cope with geological conditions; the overlapping method between membrane blocks of this application can effectively disperse stress, prevent damage caused by stress concentration, and improve the stability and durability of the engineering structure; by inspecting and protecting the welded geomembrane, the integrity and impermeability of the geomembrane are ensured, which helps to extend the service life of the geomembrane.

[0030] 2. The monorail extrusion welding process for geomembranes in this application, which uses a monorail extrusion welding machine, has a higher degree of automation and thus helps to improve construction efficiency. By setting an anti-ultraviolet layer, it can not only block ultraviolet rays from directly irradiating the substrate layer, reducing its aging and degradation rate, but also improve the mechanical properties of the geomembrane. Adjusting the welding temperature, welding time, and overlap width between adjacent membrane blocks according to the type and thickness of the geomembrane ensures welding quality.

[0031] 3. The monorail extrusion welding process of the geomembrane in this application, through the selection of suitable raw materials, proportions, and processes, enables the geomembrane to possess excellent seepage prevention effect, mechanical strength, and durability, making it suitable for various complex geological and climatic conditions. Specifically, the chemical reaction between the silane coupling agent and the hydroxyl groups on the surface of nano-SiO2 reduces the number of hydroxyl groups on the nano-SiO2 surface, thereby lowering its surface tension and preventing agglomeration. The addition of polyvinyl alcohol (PVA) allows for effective connection with the organic phase in the substrate layer at the interface, enhancing the bonding strength between the substrate layer and the UV-resistant layer. Furthermore, the oleophilic portion of nano-SiO2 can penetrate deep into the interior of PVA, better dispersing the nano-SiO2 within the PVA through entanglement with the polymer chains, fully utilizing its UV-resistant properties. Simultaneously, it increases the crystallinity of PVA and makes the molecular chain arrangement more regular. When the UV-resistant coating is applied to the substrate layer, the path for gas to permeate the substrate layer is lengthened, increasing the difficulty for gas to pass through the geomembrane, further enhancing the geomembrane's seepage prevention performance and providing a reliable seepage barrier for the reservoir bottom, thus protecting groundwater resources and the environment.

[0032] 4. The monorail extrusion welding process for the geomembrane of this application involves synergistic modification of polyester fibers using silane coupling agents and dopamine. On one hand, the hydroxyl groups of the silane coupling agent can react with the hydroxyl and amino groups of polydopamine, and on the other hand, the active groups of the silane coupling agent can react with the active groups of polydopamine and Fe... 3+ The formation of complexes allows for the coating of more silane coupling agents on the fiber surface. The hydroxyl groups exposed on the fiber surface can chemically bond with the matrix, and the amino-terminal carbon chains can entangle with the matrix. On the other hand, the adhesion of more silane coupling agents can increase the surface roughness of the fiber, which is beneficial to increase the interaction sites between the fiber and the matrix and enhance their interlocking degree, without affecting the internal structure of the fiber. Therefore, it further improves the interfacial bonding strength between the fiber and the matrix, enabling the fiber to effectively transfer loads and the interface with the matrix to withstand greater loads. Even when debonding occurs, the matrix still adheres to the fiber surface, thereby improving the mechanical properties of the geomembrane. Detailed Implementation

[0033] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0034] Unless otherwise specified in the examples, the procedures shall be performed under standard conditions or conditions recommended by the manufacturer. Raw materials or instruments whose manufacturers are not specified are all commercially available products.

[0035] Example 1

[0036] A monorail extrusion welding process for geomembranes includes:

[0037] (1) The surface of the bottom of the silo is leveled to ensure that there are no impurities within a vertical depth of 20 mm, and then the surface of the bottom of the silo is dried to ensure that the moisture content of the bottom of the silo is 10%;

[0038] (2) Based on the condition of the reservoir bottom, cut the geomembrane to a suitable size, then lay the stretched geomembrane on the surface of the reservoir bottom, and keep the overlapping area flat.

[0039] (3) TPO geomembrane, geomembrane and HDPE geomembrane are overlapped in sequence with staggered joints, with an overlap width of 10cm, and welded by a single rail extrusion welding machine at a welding temperature of 350℃ and a welding speed of 2m / min, so that the intersection point formed between the membrane blocks is T-shaped.

[0040] (4) Test the TPO geomembrane, geomembrane and HDPE geomembrane welded together in step (3), and mark and repair the defective parts until the retest is qualified;

[0041] The geomembrane includes a substrate layer and an anti-ultraviolet layer coated on the upper surface of the substrate layer, wherein the thickness ratio of the substrate layer to the anti-ultraviolet layer is 1:0.1.

[0042] The thickness ratio of the TPO geomembrane, the geomembrane, and the HDPE geomembrane is 1:1:1;

[0043] The geomembrane is prepared by the following method:

[0044] a. By weight, 15 parts of polyetheretherketone, 10 parts of polycarbonate, 8 parts of modified polyester fiber, 6 parts of boron nitride, 30 parts of high-density polyethylene, 25 parts of low-density polyethylene, 20 parts of linear low-density polyethylene, 15 parts of polyethylene and 12 parts of ethylene-octene copolymer are placed into a twin-screw extruder. The main extruder speed is 50 rpm. After extrusion through the die at 170°C, the extruder is calendered to obtain the substrate layer.

[0045] b. Disperse nano-SiO2 in a mixed solution of distilled water and anhydrous ethanol (volume ratio of 9:1), then add 3% silane coupling agent KH550 and stir until homogeneous to obtain an aqueous solution of nano-SiO2. Dissolve polyvinyl alcohol in distilled water to obtain an aqueous solution of polyvinyl alcohol. Mix the aqueous solution of polyvinyl alcohol and the aqueous solution of nano-SiO2 and place them in a water bath and stir for 20 minutes. Then place them in an ultrasonic water bath and ultrasonically disperse for 40 minutes. The weight ratio of nano-SiO2 to polyvinyl alcohol is 0.5:10. After filtration, the anti-ultraviolet coating layer is obtained.

[0046] c. Apply the UV-resistant coating to the upper surface of the substrate layer. The coating amount of the UV-resistant coating on the upper surface of the substrate layer is 180 g / m². 2 After drying, an ultraviolet-resistant layer is formed, thus producing a geomembrane;

[0047] In step a, the method for preparing modified polyester fibers includes the following steps:

[0048] S1. Soak polyester fibers in anhydrous ethanol overnight, remove and dry them to obtain pretreated polyester fibers;

[0049] S2. Add dopamine hydrochloride to Tris buffer and stir until homogeneous to prepare a dopamine solution with a concentration of 1 g / L. Then, soak the pretreated polyester fiber in the dopamine solution overnight, take it out, wash it with water, and dry it to obtain the preliminarily modified polyester fiber.

[0050] S3. Mix silane coupling agent KH550 (volume ratio 1:400) with 95% ethanol at 40°C for 1 hour, then add FeCl3 and disperse evenly. Then add the pre-modified polyester fiber and soak for 1 hour. The weight of silane coupling agent KH550 is 8% of the pre-modified polyester fiber. After washing and drying, the modified polyester fiber is obtained.

[0051] Example 2

[0052] A monorail extrusion welding process for geomembranes includes:

[0053] (1) The surface of the bottom of the silo is leveled to ensure that there are no impurities within a vertical depth of 22mm, and then the surface of the bottom of the silo is dried to ensure that the moisture content of the bottom of the silo is 13%;

[0054] (2) Based on the condition of the reservoir bottom, cut the geomembrane to a suitable size, then lay the stretched geomembrane on the surface of the reservoir bottom, and keep the overlapping area flat.

[0055] (3) TPO geomembrane, geomembrane and HDPE geomembrane are overlapped in sequence with staggered joints, with an overlap width of 11cm, and welded by a single rail extrusion welding machine at a welding temperature of 380℃ and a welding speed of 2.5m / min, so that the intersection point formed between the membrane blocks is T-shaped.

[0056] (4) Test the TPO geomembrane, geomembrane and HDPE geomembrane welded together in step (3), and mark and repair the defective parts until the retest is qualified;

[0057] The geomembrane includes a substrate layer and an anti-ultraviolet layer coated on the upper surface of the substrate layer, wherein the thickness ratio of the substrate layer to the anti-ultraviolet layer is 1:0.3.

[0058] The thickness ratio of the TPO geomembrane, the geomembrane, and the HDPE geomembrane is 1.5:1:1.2;

[0059] The geomembrane is prepared by the following method:

[0060] a. By weight, 18 parts of polyetheretherketone, 13 parts of polycarbonate, 10 parts of modified polyester fiber, 8 parts of boron nitride, 40 parts of high-density polyethylene, 28 parts of low-density polyethylene, 24 parts of linear low-density polyethylene, 20 parts of polyethylene and 15 parts of ethylene-octene copolymer are placed into a twin-screw extruder with the main extruder speed at 55 rpm. After extrusion through the die at 175°C, the extruder is calendered to obtain the substrate layer.

[0061] b. Disperse nano-SiO2 in a mixed solution of distilled water and anhydrous ethanol (volume ratio of 9:1), then add 5% silane coupling agent KH560 and stir until homogeneous to obtain an aqueous solution of nano-SiO2. Dissolve polyvinyl alcohol in distilled water to obtain an aqueous solution of polyvinyl alcohol. Mix the aqueous solution of polyvinyl alcohol and the aqueous solution of nano-SiO2 and place them in a water bath and stir for 30 minutes. Then place them in an ultrasonic water bath and ultrasonically disperse for 30 minutes. The weight ratio of nano-SiO2 to polyvinyl alcohol is 0.8:10. After filtration, the anti-ultraviolet coating layer is obtained.

[0062] c. Apply the UV-resistant coating to the upper surface of the substrate layer, with a coating amount of 200 g / m². 2 After drying, an ultraviolet-resistant layer is formed, thus producing a geomembrane;

[0063] In step a, the method for preparing modified polyester fibers includes the following steps:

[0064] S1. Soak polyester fibers in anhydrous ethanol overnight, remove and dry them to obtain pretreated polyester fibers;

[0065] S2. Add dopamine hydrochloride to Tris buffer and stir until homogeneous to prepare a dopamine solution with a concentration of 2 g / L. Then, soak the pretreated polyester fiber in the dopamine solution overnight, take it out, wash it with water, and dry it to obtain the preliminarily modified polyester fiber.

[0066] S3. Mix silane coupling agent KH560 (volume ratio 1:500) with 95% ethanol at 50°C for 2 hours. Then add FeCl3 and disperse evenly. Add the pre-modified polyester fiber and soak for 2 hours. The weight of silane coupling agent KH560 is 10% of the pre-modified polyester fiber. After washing and drying, the modified polyester fiber is obtained.

[0067] Example 3

[0068] A monorail extrusion welding process for geomembranes includes:

[0069] (1) The surface of the bottom of the silo is leveled to ensure that there are no impurities within a vertical depth of 25mm, and then the surface of the bottom of the silo is dried to ensure that the moisture content of the bottom of the silo is 15%;

[0070] (2) Based on the condition of the reservoir bottom, cut the geomembrane to a suitable size, then lay the stretched geomembrane on the surface of the reservoir bottom, and keep the overlapping area flat.

[0071] (3) TPO geomembrane, geomembrane and HDPE geomembrane are overlapped in sequence with staggered joints, with an overlap width of 12cm, and welded by a single rail extrusion welding machine at a welding temperature of 420℃ and a welding speed of 3m / min, so that the intersection point formed between the membrane blocks is T-shaped.

[0072] (4) Test the TPO geomembrane, geomembrane and HDPE geomembrane welded together in step (3), and mark and repair the defective parts until the retest is qualified;

[0073] The geomembrane includes a substrate layer and an anti-ultraviolet layer coated on the upper surface of the substrate layer, wherein the thickness ratio of the substrate layer to the anti-ultraviolet layer is 1:0.5.

[0074] The thickness ratio of the TPO geomembrane, the geomembrane, and the HDPE geomembrane is 1.8:1:1.5;

[0075] The geomembrane is prepared by the following method:

[0076] a. By weight, 20 parts of polyetheretherketone, 16 parts of polycarbonate, 13 parts of modified polyester fiber, 11 parts of boron nitride, 45 parts of high-density polyethylene, 32 parts of low-density polyethylene, 27 parts of linear low-density polyethylene, 25 parts of polyethylene and 18 parts of ethylene-octene copolymer are placed into a twin-screw extruder with the main extruder speed at 60 rpm. After extrusion through the die at 180°C, the extruder is calendered to obtain the substrate layer.

[0077] b. Disperse nano-SiO2 in a mixed solution of distilled water and anhydrous ethanol (volume ratio of 9:1), then add 7% silane coupling agent KH570 and stir until homogeneous to obtain an aqueous solution of nano-SiO2. Dissolve polyvinyl alcohol in distilled water to obtain an aqueous solution of polyvinyl alcohol. Mix the aqueous solution of polyvinyl alcohol and the aqueous solution of nano-SiO2 and place them in a water bath and stir for 40 minutes. Then place them in an ultrasonic water bath and ultrasonically disperse for 20 minutes. The weight ratio of nano-SiO2 to polyvinyl alcohol is 1.2:10. After filtration, the anti-ultraviolet coating layer is obtained.

[0078] c. Apply the UV-resistant coating to the upper surface of the substrate layer, with a coating amount of 250 g / m². 2After drying, an ultraviolet-resistant layer is formed, thus producing a geomembrane;

[0079] In step a, the method for preparing modified polyester fibers includes the following steps:

[0080] S1. Soak polyester fibers in anhydrous ethanol overnight, remove and dry them to obtain pretreated polyester fibers;

[0081] S2. Add dopamine hydrochloride to Tris buffer and stir until homogeneous to prepare a dopamine solution with a concentration of 3 g / L. Then, soak the pretreated polyester fiber in the dopamine solution overnight, take it out, wash it with water, and dry it to obtain the preliminarily modified polyester fiber.

[0082] S3. Mix silane coupling agent KH570 (volume ratio 1:600) with 95% ethanol at 60°C for 3 hours. Then add FeCl3 and disperse evenly. Add the pre-modified polyester fiber and soak for 3 hours. The weight of silane coupling agent KH570 is 12% of the pre-modified polyester fiber. After washing and drying, the modified polyester fiber is obtained.

[0083] Example 4

[0084] The difference from Example 2 is that the thickness ratio of the substrate layer to the UV-resistant layer is 1:0.01.

[0085] Example 5

[0086] The difference from Example 2 is that the thickness ratio of TPO geomembrane, geomembrane and HDPE geomembrane is 2.5:1:2.

[0087] Example 6

[0088] The difference from Example 2 is that the modified polyester fiber is replaced with polyester fiber, and the preparation method of the modified polyester fiber is not disclosed.

[0089] Example 7

[0090] The difference from Example 2 is that the method for preparing modified polyester fibers includes the following steps:

[0091] S1. Soak polyester fibers in anhydrous ethanol overnight, remove and dry them to obtain pretreated polyester fibers;

[0092] S2. Mix silane coupling agent KH560 (volume ratio 1:500) with 95% ethanol at 50°C for 2 hours. Then, add the pretreated polyester fiber and soak for 2 hours. The weight of silane coupling agent KH560 is 10% of the pretreated polyester fiber. After washing and drying, the modified polyester fiber is obtained.

[0093] Example 8

[0094] The difference from Example 2 is that the weight ratio of nano-SiO2 to polyvinyl alcohol is 3:10.

[0095] Comparative Example 1

[0096] The difference from Example 2 is that the upper surface of the substrate layer is not coated with an anti-ultraviolet layer, and the preparation method of the geomembrane does not include steps b and c.

[0097] Comparative Example 2

[0098] The difference from Example 2 is that the geomembrane was prepared by the following method:

[0099] By weight, 5 parts carbon black, 2 parts antioxidant 619, 18 parts polyetheretherketone, 13 parts polycarbonate, 10 parts modified polyester fiber, 8 parts boron nitride, 40 parts high-density polyethylene, 28 parts low-density polyethylene, 24 parts linear low-density polyethylene, 20 parts polyethylene and 15 parts ethylene-octene copolymer are placed into a twin-screw extruder. The main extruder speed is 55 rpm. After extrusion through the die at 175°C, the extruder is calendered to obtain a geomembrane.

[0100] The performance of the geomembranes in Examples 1-8 and Comparative Examples 1-2 was tested. The tensile breaking strength and elongation at break of different samples were tested according to CJ / T234-20066.6. The UV resistance of different samples was tested according to CJ / T234-20066.14. The retention of OIT under normal pressure after 1600h UV irradiation was also tested. The seepage prevention performance of different samples was tested according to CJ / T234-20066.16. Welded samples with a size of 25mm×150mm were cut, and tear and shear tests were performed on the welded parts using an Examo300F tensile testing machine. The peel strength and shear strength were taken as the average value of the two joints. The results are shown in Table 1.

[0101] Table 1

[0102]

[0103] As shown in Table 1, the single-track extrusion welding process of the geomembrane in this application is convenient to construct. The geomembrane used has both the excellent deformation adaptability of elastic materials and the weldability of plastic materials, which can provide a reliable seepage barrier for the bottom of the reservoir, thereby protecting groundwater resources and the environment.

[0104] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for preparing a geomembrane, characterized in that, The geomembrane is prepared by the following method: a. By weight, 15-20 parts of polyetheretherketone, 10-16 parts of polycarbonate, 8-13 parts of modified polyester fiber, 6-11 parts of boron nitride, 30-45 parts of high-density polyethylene, 25-32 parts of low-density polyethylene, 20-27 parts of linear low-density polyethylene, 15-25 parts of polyethylene and 12-18 parts of ethylene-octene copolymer are placed into a twin-screw extruder. The main extruder speed is 50-60 rpm. After extrusion through the die at 170-180℃, the material is calendered to obtain the substrate layer. b. Disperse nano-SiO2 in a mixed solution of distilled water and anhydrous ethanol, then add 3-7% silane coupling agent and stir until homogeneous to obtain an aqueous solution of nano-SiO2. Dissolve polyvinyl alcohol in distilled water to obtain an aqueous solution of polyvinyl alcohol. Mix the aqueous solution of polyvinyl alcohol and the aqueous solution of nano-SiO2 and place them in a water bath and stir for 20-40 minutes. Then place them in an ultrasonic water bath and ultrasonically disperse for 20-40 minutes. After filtration, the anti-ultraviolet coating layer is obtained. c. Apply the UV-resistant coating to the upper surface of the substrate layer, and after drying, form a UV-resistant layer to obtain a geomembrane. In step b, the weight ratio of nano-SiO2 to polyvinyl alcohol is (0.5-1.2):10; In step a, the method for preparing modified polyester fibers includes the following steps: S1. Soak polyester fibers in anhydrous ethanol overnight, remove and dry them to obtain pretreated polyester fibers; S2. Add dopamine hydrochloride to Tris buffer and stir until homogeneous to prepare a dopamine solution with a concentration of 1-3 g / L. Then, soak the pretreated polyester fiber in the dopamine solution overnight, take it out, wash it with water, and dry it to obtain the preliminarily modified polyester fiber. S3. Mix silane coupling agent and ethanol at a volume ratio of 1:(400-600) at 40-60℃ for 1-3 hours, then add FeCl3 and disperse evenly. Then add the preliminarily modified polyester fiber and soak for 1-3 hours. After washing and drying, the modified polyester fiber is obtained.

2. The preparation method according to claim 1, characterized in that, The silane coupling agent is selected from at least one of KH550, KH560, and KH570.

3. The preparation method according to claim 1, characterized in that, In step S3, the weight of the silane coupling agent is 8-12% of the initially modified polyester fiber.

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