A method for strengthening and repairing old HDPE cage pipes

Abstract

The present invention provides a method for strengthening and repairing old HDPE cage tubes, which comprises the following steps: (1) cleaning the surface of the old HDPE cage tube, coating epoxy structural adhesive after cleaning, then wrapping with a three-dimensional woven fabric coil, and then putting on an opening and closing mold; (2) pouring a cement-based material into the opening and closing mold, curing, demolding, and curing. When strengthening and repairing the old HDPE cage tube, the present invention adopts bionic technology, imitating the structural characteristics of bamboo. First, a three-dimensional woven fabric coil with high strength and high tensile strain rate is wrapped on the outer surface of the HDPE cage tube to be repaired, and then a cement-based material is poured through the mold to convert the original single-structured PE cylinder into a composite structure cylinder with a gradient structure, so that the old HDPE cage tube whose performance has decayed due to aging or damage can be repaired, avoiding fish escape. After repair, the overall performance of the cage can exceed that of the original HDPE cage, effectively realizing the recycling of marine aquaculture facilities such as fish farming.

Description

Technical Field

[0001] The present invention relates to the technical field of marine aquaculture, and particularly relates to a method for strengthening and repairing old HDPE cage tubes. Background Art

[0002] An HDPE cage is an aquaculture cage made of high-density polyethylene (HDPE) material, which is a common aquaculture equipment with advantages such as simple structure and low cost. This kind of cage uses relatively large-sized (φ500 - 1000mm) HDPE tubes as floats and relatively small-sized rigid plastic tubes (50 - 200mm) as skeletons. The cage is usually circular, and the diameter of the circle is generally from more than ten meters to dozens of meters. Although this kind of cage is widely used in the coastal areas of our country, it has problems such as easy deformation and easy aging. Especially in the case of strong winds and big waves, the cage is often damaged, resulting in losses of the cultured fish.

[0003] The average service life of an HDPE cage is 5 - 8 years. Among them, the early elimination due to the decrease in structural strength caused by ultraviolet degradation and seawater erosion accounts for 40% - 50% of the total annual elimination, and the damage caused by extreme weather accounts for about 30% - 40%. In the sea areas where typhoons occur frequently, the annual elimination rate of HDPE reaches 25% - 30%, and about 60% or more of them are directly related to the fracture of the floating pipe or the deformation of the frame caused by the impact of wind and waves.

[0004] The disadvantages of HDPE cages are mainly determined by the properties of the HDPE material. During the use of HDPE cages, they are prone to embrittlement and cracking due to ultraviolet radiation and seawater corrosion. Also, because the plastic structure of the float has low flexural stiffness, it is prone to plastic deformation under the action of typhoons and surges. When diseases such as aging or deformation occur in HDPE cages, there will be holes in the water body surrounded by the netting, and the fish will escape from the holes, which will bring economic losses to the farmers.

[0005] The existing methods for repairing and strengthening HDPE cages include:

[0006] (1) Simple repair: If the damage to the HDPE cage is small, it can be repaired by a simple patch method. First, the remaining water in the cage needs to be drained completely. Then, for the cracked or torn part in the float, use a blade to cut off the rough edges. Next, prepare a fiberglass patch of appropriate size to ensure that it covers an area 1 to 2 inches around the damaged area. After putting on rubber gloves, mix the epoxy resin and hardener evenly and apply it to the damaged area and the patch around it to ensure that the resin fully covers and adheres firmly.

[0007] (2)Re-welding: If the damage to the HDPE cage is relatively severe, it may be necessary to cut the damaged part and then re-weld it or use electrofusion pipe fittings for connection. This method is applicable to cases where the damaged area of the pipeline is small. After cutting off the damaged part through socket electrofusion pipe fittings, it is connected to the electrofusion sleeve.

[0008] (3)Replacing with a new section: When the damaged area of the HDPE cage is large, it is necessary to cut off the damaged pipe section and replace it with a new HDPE pipe. The interfaces can be joined by hot welding, flange connection or electrofusion connection. The last welding joint must use an electrofusion block or flange connection to ensure sealing and stability.

[0009] (4)Temporary emergency repair: In some emergency situations, if temporary emergency repair is required, instead of sawing off the HDPE pipe, a quick repair method can be adopted, such as using special repair tapes or repair sleeves for temporary plugging to maintain the basic function of the cage until permanent repair can be carried out.

[0010] It can be seen that for cages whose performance has deteriorated due to aging or failed due to deformation damage, the existing welding repair methods cannot fully restore their service performance, and it is even less likely to exceed the performance of the original product.

[0011] In addition, there are also ways such as replacing cage components and adding floats. Although these methods can solve the problem of cage damage to a certain extent, they are costly and complex to operate, and the improvement of cage function and lifespan is not significant. Due to the lack of economical and effective repair means, a large number of discarded cages are piling up, bringing certain environmental pressure. Therefore, it is of great significance to develop a simple, effective and low-cost method for repairing and strengthening HDPE cages. Summary of the Invention

[0012] In view of this, the present invention proposes a method for strengthening and repairing old HDPE cage tubes. When strengthening and repairing old HDPE cage tubes, the present invention adopts bionic technology, imitating the structural characteristics of bamboo. First, a three-dimensional woven fabric coil with high strength and high tensile strain rate is wrapped around the outer surface of the HDPE cage tube to be repaired, and then a cement-based material is poured through a mold to convert the originally single-structured HDPE cage tube into a composite structure cylinder with a gradient structure, so that the old HDPE cage tube whose performance has deteriorated due to aging or damage can be repaired, and the overall performance of the repaired cage can exceed the performance of the original HDPE cage, effectively realizing the recycling of marine aquaculture facilities.

[0013] The technical solution of the present invention is realized as follows:

[0014] A method for strengthening and repairing old HDPE cage tubes, comprising the following steps:

[0015] (1)Clean the surface of the old HDPE cage tube, apply epoxy structural adhesive after cleaning, then wrap it with a three-dimensional woven fabric coil, and then put on an opening and closing mold; the three-dimensional woven fabric coil is a three-dimensional woven fabric coil with a mixed structure made of fibers through a three-dimensional warp knitting process;

[0016] (2)Pour a cement-based material into the opening and closing mold, cure, demold, and maintain it.

[0017] Further, the thickness of the three-dimensional woven fabric coil is 4-8 mm.

[0018] Further, the fibers include one or more of aramid, polyvinyl alcohol fiber, polypropylene fiber, basalt fiber, and glass fiber.

[0019] Further, hexagonal or polygonal large holes are woven on the upper and lower surfaces of the three-dimensional woven fabric coil. The equivalent diameter of the large holes is 5 mm - 15 mm, and a large number of thin filaments perpendicular to the upper and lower surfaces pass through. The filling rate of basalt fiber in space is 1% - 3%.

[0020] Further, hook surfaces and loop surfaces of Velcro are respectively provided on both end faces of the three-dimensional woven fabric coil. When wrapping the three-dimensional woven fabric coil, the joints of the three-dimensional fabric coil are bonded through the hook surfaces and loop surfaces of Velcro, so as to quickly form a three-dimensional fiber network around the old HDPE cage tube.

[0021] Further, the opening and closing mold matches the size of the old HDPE cage tube and is composed of a symmetrical semi-circular mold I and semi-circular mold II.

[0022] Further, several needle-shaped thickness control cards are respectively arranged inside the semi-circular mold I and semi-circular mold II, and several needle-shaped sealing cards are respectively arranged at the ends of the semi-circular mold I and semi-circular mold II. The semi-circular mold I is provided with a pouring hole and an exhaust hole.

[0023] Further, the cement-based material is a sulfoaluminate cement-based material or portland cement.

[0024] Further, the sulfoaluminate cement-based material includes the following components: 700 - 800 kg / m of sulfoaluminate cement-based material 3 、120 - 180 kg / m of mineral powder 3 、100 - 150 kg / m of silica fume 3 、190 - 250 kg / m of quartz sand powder 3 、800 - 900 kg / m of ground quartz sand 3 、7 - 12 kg / m of expansive agent 3 、15 - 25 kg / m of polyethylene fiber 3, 15 - 22 kg / m of polycarboxylate water - reducing agent 3 , 150 - 230 kg / m of water 3 .

[0025] Furthermore, the Portland cement includes the following components: 720 - 800 kg / m of Portland cement 3 , 200 - 280 kg / m of fly ash 3 , 100 - 180 kg / m of silica fume 3 , 150 - 230 kg / m of slag powder 3 , 700 - 760 kg / m of ground quartz sand 3 , 10 - 20 kg / m of expansive agent 3 , 15 - 25 kg / m of polyethylene fiber 3 , 20 - 30 kg / m of polycarboxylate water - reducing agent 3 , 200 - 260 kg / m of water 3 .

[0026] Furthermore, pour the cement - based material into the opening and closing mold, vibrate it densely, let it stand for curing, demold it, and cure it, then it is okay.

[0027] Furthermore, after pouring the cement - based material, promote the densification of the cement - based material through vibration, then place it in an indoor environment at 20°C - 30°C for static curing. After curing, demold it after 12 - 24 h, then cover it with a plastic film and continue curing for 20 - 28 h. Remove the film and wrap it with geotextile, and keep it moist and continue curing for one week.

[0028] Furthermore, the vibration is carried out by means of knocking or vibrating with a vibrator, etc.

[0029] Furthermore, the cage tube of the present invention also refers to a cage buoy.

[0030] Furthermore, when the three - dimensional woven fabric roll wraps the buoy, do not apply too much force to flatten the three - dimensional configuration.

[0031] Furthermore, to avoid the magic - tape seam from hindering the flow of the cement paste, the seam of the first - layer three - dimensional fabric can be placed at the bottom of the buoy, the seam of the second - layer three - dimensional fabric can be placed at the top of the buoy, and the seam of the third layer is placed at the bottom again, and so on.

[0032] Furthermore, for a cage with a larger size, the circular - ring buoy can be divided into several segments, and the opening and closing mold can be fixed at several segments simultaneously.

[0033] Furthermore, when pouring, slowly pour the prepared cement - based material into the pouring hole, and equip with a funnel if necessary; to ensure the densification of the slurry, a small vibrator can also be equipped on the outer shell of the mold.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] (1) Composite structure innovation: Imitating the structure of bamboo, a three-dimensional woven fabric coil with high strength and high toughness is used to wrap the relatively weak HDPE cage tube, forming a gradient composite structure with a flexible interior and a rigid exterior. This structure uses the tough outer shell to resist strong wave impacts, and transfers the impact energy to the interior through the gradient composite structure, and is effectively dissipated through the flexibility of the three-dimensional woven fabric coil, flexible interface, and HDPE cage tube.

[0036] (2) Material system innovation: There are special requirements for the cement-based material used to reinforce and renew the HDPE cage tube. Simply having high strength is not sufficient (such as high-strength mortar), and having both high strength and a certain degree of toughness may not meet the requirements either (such as UHPC: ultra-high performance concrete) because the deformation caused by the impact of sea waves will quickly cause brittle fracture or cracking of the cement-based material. Instead, a material with high strength, high toughness, and a high ultimate tensile rate must be used. The cement-based material reinforced with continuous fine fibers (i.e., the sulfoaluminate cement-based material or silicate cement-based material of the present invention) just meets these conditions. And through the bonding of a double-layer or multi-layer three-dimensional fabric and an epoxy structural adhesive or the fitting of Velcro, it is closely attached to the surface of the HDPE cage tube, building a three-dimensional fiber grid, enabling the orientation and positioning of the fibers to be pre-cured in advance, providing excellent conditions for the subsequent injection of the cement-based material; and by adding components such as mineral powder, silica fume, and quartz sand powder that resist seawater erosion, anti-permeation, and anti-shrinkage in the cement-based material, it can further resist seawater erosion and ultraviolet radiation, further improving the durability, and its service life is even longer than that of the original HDPE cage.

[0037] (3) A mold that fits the HDPE cage tube: The mold is customized according to the size, arc, circumference of the recycled HDPE cage tube and the designed thickness of the protective shell. There are needle-shaped sealing cards at the ends of the mold to prevent slurry leakage during pouring; several needle-shaped thickness control cards are arranged inside the annular mold to ensure that the cement-based material has the same thickness throughout the circumference, ensuring the dimensional accuracy and apparent quality of the protective layer formed after pouring. In addition, the mold itself can be made of recycled plastic or other lightweight and inexpensive materials. This mold is the key tool for the efficient recycling of waste HDPE floats.

[0038] (4) The reinforcement and repair method of the present invention enables a large number of waste plastic cage floats and plastic parts and other materials to be reused, fully reflecting their low-carbon and environmental protection values. In addition, using the commonly used Velcro on clothes for the repair and reinforcement of cage floats is convenient, low-cost, and cost-effective, which is conducive to large-scale promotion and utilization. Brief Description of the Drawings

[0039] Figure 1 It is a schematic structural diagram of an old HDPE cage tube.

[0040] Figure 2 It is a schematic structural diagram of a three-dimensional woven fabric coil.

[0041] Figure 3 It is a schematic structural diagram of the combination of an old HDPE cage tube and a three-dimensional woven fabric coil.

[0042] Figure 4 It is a schematic diagram of the wrapping and winding method of a three-dimensional fabric on an old HDPE cage tube.

[0043] Figure 5 It is a schematic diagram of a three-dimensional woven fabric coil and an opening and closing mold wrapping an HDPE cage tube.

[0044] Figure 6 It is a schematic diagram of the use of an opening and closing mold.

[0045] Figure 7 It is a schematic diagram of the use of a sealing card and a thickness control card.

[0046] Figure 8 It is a schematic diagram of the Velcro bonding at the joint.

[0047] In the figure, 1 - HDPE cage tube, 2 - three-dimensional woven fabric coil, 3 - opening and closing mold, 301 - semi-circular mold I, 302 - semi-circular mold II, 303 - thickness control card, 304 - sealing card, 305 - exhaust hole, 306 - pouring hole, 4 - funnel, 5 - hook surface of Velcro, 6 - loop surface of Velcro. Detailed implementation method

[0048] To better understand the technical content of the present invention, specific embodiments are provided below to further illustrate the present invention.

[0049] Unless otherwise specified, the experimental methods used in the embodiments of the present invention are all conventional methods.

[0050] Unless otherwise specified, the materials, reagents, etc. used in the embodiments of the present invention can all be obtained from commercial channels.

[0051] The epoxy structural adhesive of the present invention is manufactured by Beijing Dinggu Weiye Engineering Materials Co., Ltd., the product name is modified epoxy resin interface adhesive, and the product material is epoxy resin.

[0052] Example 1

[0053] The opening and closing mold 3 of this embodiment is dimensionally matched with the old HDPE cage tube 1 and is composed of a symmetric semi-circular mold I 301 and a semi-circular mold II 302; several needle-shaped thickness control cards 303 are respectively arranged inside the semi-circular mold I 301 and the semi-circular mold II 302, and several needle-shaped sealing cards 304 are respectively arranged at the ends of the semi-circular mold I 301 and the semi-circular mold II 302. The semi-circular mold I 301 is provided with a pouring hole 306 and a vent hole 305.

[0054] This embodiment uses a sulfoaluminate cement-based material, and the mix ratio and performance are shown in the following table:

[0055] Table 1 Mix ratio of sulfoaluminate cement-based material (unit: kg / m 3 )

[0056]

[0057] The preparation method of this sulfoaluminate cement-based material is as follows: Dissolve the polycarboxylate water reducer in water to obtain a mixed water solution for standby; then place various powder materials such as sulfoaluminate cement, mineral powder, silica fume, quartz sand powder, ground quartz sand, expansive agent, and polyethylene fiber in a stirring pot, and dry mix slowly for 2 minutes, and then add the mixed water solution while stirring to obtain a mixture. When the fluidity of the mixture increases to the point where it can flow freely, stir at a high speed for 3 minutes to obtain a high-fluidity sulfoaluminate cement-based material for standby.

[0058] The three-dimensional woven fabric coil 2 of this embodiment is a three-dimensional woven fabric coil 2 with a mixed structure made of basalt fiber through a three-dimensional warp knitting process. Its thickness is 5 mm, and hexagonal or polygonal large holes are woven on the upper and lower surfaces of the three-dimensional woven fabric coil 2. The equivalent diameter of the large holes is 5 mm to 15 mm, and a large number of thin filaments perpendicular to the upper and lower surfaces pass through. The filling rate of basalt fiber in space is 2%.

[0059] The method for strengthening and repairing the old HDPE cage tube 1 of this embodiment includes the following steps:

[0060] (1) Clean the surface of the old HDPE cage tube 1, remove the dirt and attachments on the surface, ensure that the surface of the buoy is clean and flat. After cleaning, apply epoxy structural adhesive on the surface of the old HDPE cage tube 1. Before the epoxy structural adhesive cures, wrap it with a three-dimensional woven fabric coil 2, and bond the joints of the three-dimensional fabric coil through the hook surface 5 and the loop surface 6 of the magic tape connected to the three-dimensional woven fabric coil 2, so as to quickly form a three-dimensional fiber network around the old HDPE cage tube 1. Wrap another layer of three-dimensional woven fabric coil 2 on the outer surface of the wrapped three-dimensional fabric, and then put on an opening and closing mold 3 composed of a symmetrical semi-circular mold Ⅰ 301 and a semi-circular mold Ⅱ 302 that matches the size of the HDPE cage tube 1. The opening and closing mold 3 can wrap the old HDPE tube from the outside. The inner space of the opening and closing mold 3 just accommodates the three-dimensional woven fabric coil 2. After the opening and closing mold 3 is closed, the needle-shaped thickness control card 303 just contacts the surface of the HDPE cage tube 1, which is used to control the thickness of the sulfoaluminate cement-based material and keep the opening and closing mold 3 and the HDPE cage tube 1 always on the same concentric circle. At the end of the opening and closing mold 3, there are relatively dense needle-shaped sealing cards 304 for sealing the cement slurry within the opening and closing mold 3. The semi-circular mold Ⅰ 301 is provided with a pouring hole 306 and a vent hole 305 to facilitate the dense molding of the sulfoaluminate cement-based material;

[0061] (2) Pour the sulfoaluminate cement-based material into the pouring hole 306 of the opening and closing mold 3 through a funnel 4, then vibrate it with a vibrator to promote the densification of the cement-based material, and then place it in an indoor environment of 20°C - 30°C for static curing. After 12 hours, it can be demolded and covered with a plastic film for continued curing for 24 hours. Then remove the film, wrap it with geotextile instead, and keep it moist for continued curing for one week.

[0062] Example 2

[0063] The opening and closing mold 3 of this example matches the size of the old HDPE cage tube 1 and is composed of a symmetrical semi-circular mold Ⅰ 301 and a semi-circular mold Ⅱ 302; several needle-shaped thickness control cards 303 are respectively arranged inside the semi-circular mold Ⅰ 301 and the semi-circular mold Ⅱ 302, and several needle-shaped sealing cards 304 are respectively arranged at the ends of the semi-circular mold Ⅰ 301 and the semi-circular mold Ⅱ 302. The semi-circular mold Ⅰ 301 is provided with a pouring hole 306 and a vent hole 305.

[0064] This example uses a Portland cement-based material, and the mix ratio and performance are shown in the following table:

[0065] Table 2 Mix ratio of Portland cement-based material (unit: kg / m 3 )

[0066]

[0067] The preparation method of the portland cement-based material is as follows: Dissolve the polycarboxylate water reducer in water to obtain a mixed aqueous solution for standby; then place various powders such as portland cement, fly ash, silica fume, slag powder, ground quartz sand, expansive agent, and polyethylene fiber in a stirring pot, and dry mix slowly for 2 minutes, and then add the mixed aqueous solution while stirring to obtain a mixture. When the fluidity of the mixture increases to the point where it can flow freely, stir at a high speed for 3 minutes to obtain a high-fluidity sulfoaluminate cement-based material for standby.

[0068] The three-dimensional braided fabric roll 2 in this embodiment is a three-dimensional braided fabric roll 2 with a mixed structure made of polyvinyl alcohol fibers through a three-dimensional warp knitting process. Its thickness is 5 mm. Hexagonal or polygonal large holes are woven on the upper and lower surfaces of the three-dimensional braided fabric roll 2. The equivalent diameter of the large holes is 5 mm to 15 mm. A large number of thin filaments perpendicular to the upper and lower surfaces pass through. The filling rate of the polyvinyl alcohol fibers in space is 3%.

[0069] The method for strengthening and repairing the old HDPE cage tube 1 in this embodiment includes the following steps:

[0070] (2) Clean the surface of the old HDPE cage tube 1 to remove dirt and attachments on the surface, ensure that the surface of the buoy is clean and flat. After cleaning, apply epoxy structural adhesive on the surface of the old HDPE cage tube 1. Before the epoxy structural adhesive cures, wrap the three-dimensional braided fabric roll 2, and bond the joints of the three-dimensional fabric roll through the hook surface 5 and the loop surface 6 of the magic tape connected to the three-dimensional braided fabric roll 2, so as to quickly form a three-dimensional fiber network surrounding the old HDPE cage tube 1. Wrap another layer of three-dimensional braided fabric roll 2 on the outer surface of the already wrapped three-dimensional fabric, and then put on an opening and closing mold 3 composed of a symmetric semi-circular mold Ⅰ 301 and a semi-circular mold Ⅱ 302 that matches the size of the HDPE cage tube 1. The opening and closing mold 3 can wrap the old HDPE tube from the outside. The inner space of the opening and closing mold 3 just accommodates the three-dimensional braided fabric roll 2. After the opening and closing mold 3 is closed, the needle-shaped thickness control card 303 just contacts the surface of the HDPE cage tube 1, which is used to control the thickness of the portland cement-based material and keep the opening and closing mold 3 and the HDPE cage tube 1 always on the same concentric circle; At the end of the opening and closing mold 3, there is a relatively dense needle-shaped sealing card 304 for sealing the cement slurry inside the opening and closing mold 3. The semi-circular mold Ⅰ 301 is provided with a pouring hole 306 and a vent hole 305 to facilitate the dense molding of the portland cement-based material;

[0071] (2)Pour the silicate cement-based material into the pouring hole 306 of the opening and closing mold 3, then vibrate it by knocking to promote the compaction of the cement-based material, and then place it in an indoor environment of 20°C to 30°C for static curing. After 12 hours, it can be demolded and covered with a plastic film for continued curing for 24 hours. Then, remove the film, wrap it with geotextile, and keep it moist for continued curing for one week, and that's it.

[0072] It is found through testing that the compressive strength of the HDPE pipe barrel for aquaculture cages is 20 MPa, and its flexural modulus is 1 GPa. The elastic modulus of the old HDPE cage pipe barrels strengthened and repaired by the methods of the above-mentioned Embodiment 1 and Embodiment 2 of the present invention is above 35 GPa. It shows that the method of the present invention can effectively reinforce and repair the old HDPE cage pipe barrels, improve the performance of the old HDPE cage pipe barrels, enhance the ability to resist deformation, significantly improve the ability to withstand wind and waves, and effectively realize the recycling of marine aquaculture facilities.

[0073] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for strengthening and repairing old HDPE cage pipes, characterized in that, The steps include the following: (1) Clean the surface of the old HDPE cage tube, apply epoxy structural adhesive after cleaning, then wrap it with a three-dimensional braided fabric roll, and then put on an opening and closing mold; the three-dimensional braided fabric roll is a three-dimensional braided fabric roll with a mixed structure made of fibers through a three-dimensional warp knitting process; hexagonal large holes are woven on the upper and lower surfaces of the three-dimensional braided fabric roll, the equivalent diameter of the large holes is 5 mm to 15 mm, a large number of filaments perpendicular to the upper and lower surfaces pass through, and the filling rate of basalt fibers in space is 1% to 3%; the opening and closing mold matches the size of the old HDPE cage tube and is composed of a symmetric semi-circular mold I and a semi-circular mold II; several needle-shaped thickness control cards are respectively arranged inside the semi-circular mold I and the semi-circular mold II, and several needle-shaped sealing cards are respectively arranged at the ends of the semi-circular mold I and the semi-circular mold II, and a pouring hole and an exhaust hole are opened on the semi-circular mold I; (2) Pour a cement-based material into the opening and closing mold, cure, demold, and maintain it, then it is ready.

2. The method for strengthening and repairing old HDPE cage pipes according to claim 1, characterized in that, The thickness of the three-dimensional braided fabric roll is 4 to 8 mm; the fibers include one or more of aramid, polyvinyl alcohol fiber, polypropylene fiber, basalt fiber, and glass fiber.

3. The method for strengthening and repairing old HDPE cage pipes according to claim 1, characterized in that, Magic hook surfaces and magic loop surfaces are respectively arranged on the two end faces of the three-dimensional braided fabric roll. When wrapping the three-dimensional braided fabric roll, the joints of the three-dimensional fabric roll are bonded through the magic hook surfaces and the magic loop surfaces, so as to quickly form a three-dimensional fiber network around the old HDPE cage tube.

4. The method for strengthening and repairing old HDPE cage pipes according to claim 1, characterized in that, The cement-based material is a sulfoaluminate cement-based material or a silicate cement-based material.

5. The method for strengthening and repairing old HDPE cage pipes according to claim 4, characterized in that, The sulfoaluminate cement-based material comprises the following components: 700-800 kg / m of sulfoaluminate cement-based material 3 , 120-180 kg / m of mineral powder 3 , 100-150 kg / m of silica fume 3 , 190-250 kg / m of quartz sand powder 3 , 800-900 kg / m of ground quartz sand 3 , 7-12 kg / m of expansion agent 3 , 15-25 kg / m of polyethylene fiber 3 , 15-22 kg / m of polycarboxylate water reducer 3 , 150-230 kg / m of water 3 .

6. The method for strengthening and repairing old HDPE cage pipes according to claim 4, characterized in that, The silicate cement-based material comprises the following components: 720-800 kg / m of silicate cement 3 , 200-280 kg / m of fly ash 3 , 100-180 kg / m of silica fume 3 , 150-230 kg / m of ground granulated blast-furnace slag 3 , 700-760 kg / m of ground quartz sand 3 , 10-20 kg / m of expansion agent 3 , 15-25 kg / m of polyethylene fiber 3 , 20-30 kg / m of polycarboxylate superplasticizer 3 , 200-260 kg / m of water 3 .

7. The method for strengthening and repairing old HDPE cage pipes according to claim 1, characterized in that, After pouring the cement-based material, vibration is used to promote the densification of the cement-based material, and then it is placed in an indoor environment of 20°C to 30°C for static curing. After curing, it is demolded after 12 to 24 hours, then covered with a plastic film and continued to be maintained for 20 to 28 hours. The film is removed, and it is wrapped with geotextile instead and kept moist for continued maintenance for one week.

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