Composite temperature control drainage geotextile

Abstract

The invention discloses a composite temperature-control drainage geotextile, and relates to the technical field of geosynthetic materials. The geotextile comprises a drainage layer which is of a three-dimensional water guide structure formed by biaxial warp knitting of special-shaped section wicking fiber bundles and polypropylene reinforced fiber bundles and used for efficient drainage; the reinforcing layer is of a grid structure which is formed by hot melting and bonding ultra-high molecular weight polyethylene fibers and has high tensile strength, and provides mechanical support; the heating layer is composed of carbon fiber heating wires which are arranged in parallel in a snakelike mode and electrically connected in series, and the heating layer is embedded in a quilting seam channel between the drainage layer and the reinforcing layer and can achieve active heating of soil; the temperature control module comprises a temperature sensor in the enhancement layer and a temperature control device connected with the heating layer in series, and the heating power can be dynamically adjusted according to a preset temperature threshold value. By means of the multi-layer composite structure and the intelligent temperature control system, effective integration of drainage, enhancement and active anti-freezing functions is achieved, and the engineering application performance of the geotechnical cloth in the cold environment is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of geosynthetics, and particularly relates to a composite temperature-controlled drainage geotextile integrating drainage, mechanical reinforcement, and active heating regulation functions. Background Art

[0002] In cold regions and seasonally frozen soil regions, the freeze-thaw cycle of soil is a key factor causing geotechnical structure diseases. When the ambient temperature drops below the freezing point, the pore water in the soil freezes, and the volume expands to generate frost heaving force, resulting in problems such as pavement heaving, cracking, uneven settlement of the foundation, slope instability, and damage to hydraulic structures.

[0003] As an important geosynthetic material, geotextiles are widely used in geotechnical engineering, mainly playing roles such as isolation, filtration, drainage, reinforcement, and protection; traditional drainage geotextiles can drain some of the liquid water in the soil, but cannot drain the water in the frozen soil at low temperatures; although the reinforced geotextiles can improve the tensile strength and bearing capacity of the soil, they cannot actively cope with the threat of frost damage.

[0004] In recent years, there have been some attempts to combine heating elements with geotechnical materials, such as using resistance wire meshes, carbon fiber heating cables, or electric heating films. However, these existing technical solutions often have one or more of the following deficiencies: 1. Insufficient heating efficiency and uniformity: Simple arrangement of heating elements may lead to local overheating or insufficient heating, making it difficult to accurately control the soil temperature; 2. Poor durability and reliability: The heating elements are easily damaged in a complex soil environment and construction stress, the insulation performance deteriorates, and even short circuits may occur; 3. Single function or low integration degree: Existing heating geotechnical materials may lack efficient drainage functions or sufficient mechanical reinforcement effects, making it difficult to meet the multiple requirements of complex projects; 4. Low degree of intelligence: Most heating systems lack real-time temperature monitoring and intelligent power adjustment capabilities, resulting in energy waste or poor anti-freezing effects; 5. Complicated construction and maintenance: The integration of the heating system and the geotextile, power connection, sensor arrangement, etc. may be relatively cumbersome, and the later maintenance cost is high.

[0005] Therefore, the market urgently needs a new type of geotechnical material with reasonable structural design, comprehensive functions, reliable performance, intelligent control, and convenient construction to effectively solve the frost damage problems in cold region projects. Summary of the Invention

[0006] The main objective of the present invention is to overcome the above-mentioned defects of the prior art and provide a composite temperature-controlled drainage geotextile. This geotextile aims to achieve the synergistic effect of three major functions, namely efficient drainage, excellent mechanical reinforcement, and precise active temperature control, through its unique multi-layer composite structure and intelligent control system. It is applicable to engineering projects such as road subgrades, railway beds, water conservancy projects, airport pavement foundations, landfill covers, and various slopes in cold regions. By actively heating, it prevents soil freezing, reduces the frost heaving source through efficient drainage, and maintains the stability of the engineering body through structural reinforcement.

[0007] To achieve the above objective, the present invention provides a composite temperature-controlled drainage geotextile, comprising: (a) A drainage layer 100, formed by a three-dimensional water-conducting structure with capillary water-conducting channels through a double-axial warp knitting process using profiled cross-section capillary fiber bundles 110 and polypropylene reinforcing fiber bundles 120; this structure utilizes the capillary action and pore network of the fibers to achieve the rapid collection and discharge of excess water in the soil. (b) A reinforcement layer 200, provided on one side of the drainage layer 100, formed by a grid structure through a hot melt bonding process using ultra-high molecular weight polyethylene fibers. This reinforcement layer has excellent tensile strength and provides the main mechanical support and reinforcement effect for the geotextile. (c) A heating layer 300, including a plurality of parallel and serpentine-arranged carbon fiber heating wires 310, which are electrically connected in series and firmly embedded in a preset quilting channel 400 between the drainage layer 100 and the reinforcement layer 200; the width of the quilting channel 400 is designed to be 1.2 to 1.5 times the diameter of the carbon fiber heating wire 310 to ensure good fixation of the carbon fiber heating wire and appropriate heat dissipation space. (d) A temperature control module, electrically connected to the power supply circuit of the heating layer 300, for real-time monitoring of the temperature of the geotextile itself or the adjacent soil and intelligent control of the heating power of the heating layer 300 according to the monitoring results; the temperature control module at least includes: at least two, preferably multiple to form an array to improve the monitoring coverage and accuracy, temperature sensors 701 located at specific positions inside or on the surface of the reinforcement layer 200 at a predetermined interval for real-time acquisition of temperature data; and a temperature control device 702, connected to the heating layer 300 and configured to dynamically adjust the output power of the heating layer 300 according to a preset soil freezing temperature threshold.

[0008] In a preferred embodiment, the cross-section of the special-section wicking fiber bundle 110 of the drainage layer 100 is designed to have a single fiber cross-section with at least three capillary protrusions 111 extending in the radial direction of the fiber. These protrusions form grooves on the fiber surface, and adjacent capillary protrusions 111 form longitudinal drainage channels 112 with a width of 3-5 μm. This microstructure greatly increases the specific surface area of the fiber and utilizes the capillary phenomenon to enhance the adsorption of liquid water and the conduction capacity along the axial direction of the fiber.

[0009] In a more specific embodiment, the diameter of the monofilament in the shaped cross-section wicking fiber bundle 110 is controlled within the range of 10-15 μm, and each bundle of shaped cross-section wicking fiber bundles can contain 400-600 such fiber monofilaments. In the fabric structure of the drainage layer 100, the fiber bundle density in the warp direction can be set to 50-70 strands / cm, and the fiber bundle density in the weft direction can be set to 40-60 strands / cm. The specification of the polypropylene reinforced fiber bundle 120 is selected to be 4400D, and its weaving ratio with the shaped cross-section wicking fiber bundle 110 in the drainage layer fabric can be 2:1 to 4:1, so as to ensure sufficient drainage channels while giving the drainage layer a certain initial strength and structural stability; when the drainage layer is manufactured by the biaxial warp knitting process, the swing angle of the guide needle is preferably controlled between 35°-45°, which helps to form a stable and porous three-dimensional network structure.

[0010] In a preferred embodiment, when the ultra-high molecular weight polyethylene fibers of the reinforcing layer 200 are hot-melt bonded, the temperature is controlled at 180-200° C., the pressure is controlled at about 0.5 MPa, and the hot pressing time is 30-60 seconds. This process parameter range helps the ultra-high molecular weight polyethylene fiber surfaces to fully melt and bond to each other to form firm nodes, while avoiding excessive thermal degradation of the material.

[0011] In a preferred embodiment, the quilted channel 400 between the drainage layer 100 and the reinforcement layer 200 can be first formed by a lockstitch quilting process. The spacing between adjacent quilted channels 400 is 5-15 cm to ensure uniformity and coverage of heating while optimizing material usage. The carbon fiber heating wire 310 is inserted into the quilted channel 400 according to a preset curved path. Its electrode transition section 510, that is, the connection part between the end of the carbon fiber heating wire and the external power supply wire, is firmly fixed to the edge of the reinforcement layer 200 or the predetermined wiring area through a double-sided conductive tape 600 with good conductivity and adhesion to ensure the reliability of electrical connection.

[0012] In a preferred embodiment, the carbon fiber heating wire 310 adopts a multi-layer composite structure to improve its electrical performance, mechanical strength and environmental tolerance, and includes, from inside to outside: Carbon fiber core 311: As the main heating body, it is composed of at least 3000 high-strength and high-modulus carbon fiber filaments of specifications such as 6K, 12K, or 24K, which are tightly integrated into a bundle shape, and has a low resistivity to ensure efficient electro-thermal conversion; Inner insulation layer 312: Tightly coated on the outer surface of the carbon fiber core 311, and materials with high temperature resistance and high insulation strength are selected, such as polyimide (PI) film, fluorinated ethylene propylene (FEP), or ceramized silicone rubber. Its thickness is 0.1 - 0.3 mm, and the breakdown voltage requirement is not less than 3 kV / mm to ensure electrical insulation safety under the working voltage; Electromagnetic shielding layer 313: Covered on the outer surface of the inner insulation layer 312, used to shield the electromagnetic field generated when the carbon fiber heating wire works, and reduce potential interference to the surrounding environment and electronic devices. It is made of materials with good conductivity, such as a high-density woven silver-plated aramid fiber layer, copper foil tape, or non-woven fabric coated with graphene / conductive polymer, and its surface resistivity requirement is not greater than 1×10² Ω / sq; And outer protective layer 314: As the outermost layer, coated on the outer surface of the electromagnetic shielding layer 313, providing mechanical protection, abrasion resistance, chemical corrosion resistance, weather resistance (anti-ultraviolet, resistance to high and low temperature cycles), and a certain degree of flexibility. Materials such as fluororubber with a Shore hardness of 60 - 80A, modified polyurethane (TPU) elastomer, or wear-resistant nylon can be selected. Its thickness is 0.5 - 1.0 mm, and it is required to have excellent flexural resistance.

[0013] In a preferred embodiment, in order to improve the reliability and maintainability of the system, the heating layer 300 adopts a segmented power supply design, in which the carbon fiber heating wires 310 constituting the heating layer 300 are organized into several independent heating units, and the length of each unit is 5 - 20 m. Each of the independent heating units is connected to two spaced power supply wires through a special connector or welding method. The power supply wires are electrically connected to the energy storage structure. The working voltage of each independent heating unit is designed as a safe low voltage, not greater than 48V DC, to reduce the risk of electric shock. Through precise calculation and manufacturing control, it is ensured that the total resistance difference between the independent heating units is not greater than 5%, so as to ensure the uniformity of the heating power over the entire geotextile area.

[0014] In a preferred embodiment, the temperature control device 702 is further configured to: set the soil freezing temperature threshold as a parameter that can be flexibly adjusted according to specific engineering geological conditions, climatic environment, and anti-freezing objectives, and based on this threshold and the real-time temperature data obtained from the temperature sensor 701, execute a control algorithm or other advanced control strategies to dynamically adjust the average heating power applied to the heating layer 300. This intelligent adjustment method can minimize temperature fluctuations, accurately maintain the target temperature, and significantly improve energy utilization efficiency. The temperature sensor 701 is tightly fixed and effectively thermally conducted with the fibers or matrix of the reinforcement layer 200 through a flexible graphene conductive adhesive with good thermal conductivity and adhesiveness.

[0015] In a preferred embodiment, to ensure the integrity and long-term stability of each structural layer of the composite geotextile, the drainage layer 100, the reinforcement layer 200, and the heating layer 300 embedded between the two are integrally fixed by a lockstitch quilting along a preset stitching path through a suture 500 to form a composite structure.

[0016] In the above embodiment of stitching and fixing, to protect the carbon fiber heating wire 310 from damage and ensure electrical safety, the design of the stitching path is crucial. It should be ensured that the stitching line (stitches) avoids the area directly penetrated by the carbon fiber heating wire 310, and the edge of the stitches is not less than 3 mm away from the edge of the carbon fiber heating wire 310 to isolate the puncture of the sewing needle and the friction of the suture, preventing damage to the insulation layer or core of the carbon fiber heating wire, and thus avoiding potential short-circuit or leakage risks.

[0017] Compared with the prior art, a composite temperature-controlled drainage geotextile provided by the present invention has the following remarkable beneficial effects: 1. Highly integrated functions and synergistic effect: The present invention integrates three functions of efficient drainage, strong reinforcement, and intelligent active temperature control into an integrated composite material. The drainage layer quickly removes moisture, reducing the amount of frost heave water at the source; the reinforcement layer provides excellent mechanical support to maintain the stability of the soil structure; the heating layer actively prevents soil freezing through precise temperature control. The three work together to comprehensively solve multiple challenges faced by projects in cold regions; 2. Excellent drainage performance: A three-dimensional water-conducting structure jointly constructed by specially designed profiled cross-section wicking fiber bundles and polypropylene reinforcing fiber bundles is adopted. By utilizing the enhanced capillary effect and optimized pore network, efficient and rapid collection and drainage of excess water in the soil are achieved; 3. Excellent mechanical reinforcement effect: The reinforcement layer is made of ultra-high molecular weight polyethylene fibers with high strength and high modulus, significantly improving the overall tensile strength, tear strength, puncture resistance, and wear resistance of the geotextile, and can effectively restrain soil deformation and improve bearing capacity; 4. Precise and energy-saving intelligent temperature control: The carbon fiber heating wire has excellent electrothermal conversion efficiency, fast response characteristics, and good flexibility. Combined with optimized layout methods such as serpentine, segmented power supply design, and intelligent temperature control module, precise dynamic adjustment of heating power is achieved, ensuring uniform heating and stable temperature near the antifreeze threshold, avoiding the phenomena of "overheating" or "underheating", significantly reducing energy consumption, and enabling remote unattended monitoring; 5. Structural stability and durability: The multi-layer protection structure of the carbon fiber heating wire itself endows it with excellent weather resistance, chemical corrosion resistance, and anti-mechanical damage ability. It ensures the long-term service life and performance stability of the product in complex engineering environments; 6. Wide engineering applicability: The present invention can be widely applied to various geotechnical engineering in cold regions and seasonally frozen soil regions, such as roads, railways, airports, water conservancy, municipal, environmental protection and other fields, effectively preventing frost damage, ensuring project safety and extending project life. Description of the Drawings

[0018] Figure 1 It is a schematic structural layer cross-sectional view of a composite temperature-controlled drainage geotextile of the present invention; Figure 2 It is a schematic diagram of the biaxial warp-knitted three-dimensional water-conducting structure of the drainage layer of the present invention; Figure 3 It is a schematic cross-sectional view of the cross-section of the profiled core absorption fiber of the present invention; Figure 4 It is a schematic multi-layer structure cross-sectional view of the carbon fiber heating wire of the present invention; Figure 5 It is a schematic connection diagram of the heating layer and the temperature control module of the present invention; Figure 6 It is a schematic diagram of the carbon fiber heating wire and the interlayer quilting channel of the present invention; Figure 7 It is a schematic structural cross-sectional view of the composite temperature-controlled drainage geotextile laid in the highway subgrade in cold regions in Embodiment 2 of the present invention.

[0019] Reference Signs: 100 - Drainage layer; 110 - Profiled core absorption fiber bundle; 111 - Capillary protrusion; 112 - Longitudinal drainage channel; 120 - Polypropylene reinforcing fiber bundle; 200 - Reinforcement layer; 300 - Heating layer; 310 - Carbon fiber heating wire; 311 - Carbon fiber core; 312 - Inner insulation layer; 313 - Electromagnetic shielding layer; 314 - Outer protective layer; 400 - Quilting channel; 410 - Quilting thread; 500 - Suture; 510 - Electrode transition section; 600 - Double-sided conductive tape; 701 - Temperature sensor; 702 - Temperature control device; 801 - Roadbed; 802 - Gravel layer; 803 - First composite temperature-controlled drainage geotextile layer; 804 - Filling layer; 805 - Cement stabilized macadam base course; 806 - Second composite temperature-controlled drainage geotextile layer; 807 - Road surface layer; 808 - Drainage ditch; 809 - Battery pack; 810 - Controller; 811 - Photovoltaic module; 812 - Fan assembly. Detailed implementation manners

[0020] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0021] Embodiment 1: Refer to Figures 1 to 6 This embodiment provides a preparation method for a composite temperature-controlled drainage geotextile.

[0022] I. Structural composition of the composite temperature-controlled drainage geotextile: As Figure 1 shown, the typical structure of the composite temperature-controlled drainage geotextile in this embodiment sequentially includes a drainage layer 100, a heating layer 300, and a reinforcing layer 200 from top to bottom.

[0023] Drainage layer 100: Refer to Figure 2 This layer is formed by knitting a profiled cross-section wicking fiber bundle 110 and a polypropylene reinforcing fiber bundle 120 through a bi-axial warp knitting process to form a three-dimensional water-conducting structure with good pore connectivity; Refer to Figure 3 The single filament diameter of the profiled cross-section wicking fiber bundle 110 is controlled at 12 μm. Each single filament has 4 leaf-shaped capillary protrusions 111 evenly distributed in the radial direction on its cross-section. These protrusions significantly increase the fiber surface area, and a longitudinal drainage channel 112 with a width of about 4 μm is naturally formed between adjacent capillary protrusions 111. This structure greatly enhances the capillary water absorption capacity of the fiber and the water conduction efficiency along the fiber axis. Each bundle of profiled cross-section wicking fiber bundles 110 contains about 500 such fiber filaments; The profiled cross-section wicking fiber bundle 110 is used as the skeleton material and is mixed and knitted with a 4400D specification polypropylene reinforcing fiber bundle 120 at a quantity ratio of 2:1. During the warp knitting process, the warp density of the drainage layer 100 is set at 60 roots / cm, and the weft density is 50 roots / cm. The swing angle of the guide yarn needle of the bi-axial warp knitting machine is controlled at 40°.

[0024] Reinforcement layer 200: This layer is mainly composed of ultra-high molecular weight polyethylene fibers. During manufacturing, the ultra-high molecular weight polyethylene fibers are evenly laid into a fiber mat through an air-laid equipment, and then hot-pressed for 45 seconds at a temperature of 190°C and a pressure of 0.5 MPa by a hot press plate. The ultra-high molecular weight polyethylene fibers partially melt and bond to each other under these conditions, and form the reinforcement layer 200 with a stable grid structure after cooling.

[0025] Heating layer 300: Refer to Figure 5 , the main body of the heating layer 300 is a number of parallel and regularly serpentine carbon fiber heating wires 310. These carbon fiber heating wires 310 are precisely threaded through the quilting channels 400 formed by a lockstitch quilting process. The width of the quilting channels 400 is designed to be 1.3 times the outer diameter of the used carbon fiber heating wires 310. The center distance between adjacent parallel quilting channels 400 is 10 cm; Refer to Figure 4 , in this embodiment, the multi-layer structure of the carbon fiber heating wire 310 from the inside to the outside is as follows: Carbon fiber core 311: Using a 12K specification polyacrylonitrile-based carbon fiber bundle, that is, containing 12,000 carbon fiber filaments with a diameter of 6 μm; Inner insulation layer 312: A layer of polyimide (PI) film with a thickness of 0.2 mm, its temperature resistance grade reaches 220°C, and the breakdown voltage is as high as 4 kV / mm; Electromagnetic shielding layer 313: A layer of tightly woven silver-plated aramid fiber mesh with a weaving density of 95%, and the measured surface resistivity value is 8×10¹ Ω / sq; Outer protection layer 314: A layer of fluororubber (FKM) sheath with a thickness of 0.8 mm, its Shore A hardness is 70, and it has excellent wear resistance, oil resistance, chemical corrosion resistance and weather resistance. In terms of the electrical connection of the heating layer 300, each section of the carbon fiber heating wire 310 is connected in series to form one or more heating circuits in this embodiment. The electrode transition sections 510 at both ends have been pre-connected and led out reliably with the internal carbon fiber core, and are firmly pasted and fixed to the designated area at the edge of the reinforcement layer 200 through a double-sided conductive tape 600 with a peel strength of 6 N / cm, facilitating subsequent connection with the temperature control module. The heating layer 300 of this embodiment adopts a segmented design, organizing the carbon fiber heating wire 310 into independently controllable heating units, with each 10-meter length constituting an independent heating unit, the designed working voltage is 48V DC, and the total resistance difference between each unit is ensured to be controlled within 3%.

[0026] Temperature control module: Refer to Figure 5, the temperature control module is connected to the power supply circuit of the heating layer 300 to achieve intelligent monitoring and adjustment of the heating process. This module mainly includes: Temperature sensor array: In this embodiment, the temperature sensor 701 is tightly fixed to the fiber matrix of the reinforcing layer 200 through flexible graphene conductive adhesive to ensure rapid and accurate heat sensing; Temperature control device 702: The core is a control board based on a microcontroller, which is used to collect the resistance signal of the temperature sensor 701 and convert it into a temperature value. According to these real-time temperature data and the soil freezing temperature threshold preset by the user, through a preset control algorithm, the required heating power is further calculated. Then, by dynamically adjusting the average voltage applied to the heating layer 300, fine control of the heating power is achieved.

[0027] II. Preparation method steps of the composite temperature-controlled drainage geotextile: S1: Prepare the drainage layer 100: Select the profiled cross-section wick fiber bundle 110 and polypropylene reinforcing fiber bundle 120 according to the above specifications, and weave them on a biaxial warp knitting machine at a ratio of 2:1, a warp density of 60 roots / cm, a weft density of 50 roots / cm, and a guide needle swing angle of 40° to obtain the drainage layer fabric.

[0028] S2: Prepare the reinforcing layer 200: After the ultra-high molecular weight polyethylene fibers are air-laid, they are hot-pressed at 190°C and 0.5 MPa for 45 seconds to form a grid-shaped reinforcing layer.

[0029] S3: Form the quilting channel 400 and lay the heating layer 300: The quilting channel 400 is formed between the drainage layer 100 and the reinforcing layer 200 by using a lockstitch quilting process. Then, the prepared carbon fiber heating wire 310 is threaded through the channel and connected in series according to the design, and its electrode transition section 510 is fixed at a predetermined position on the reinforcing layer 200 with double-sided conductive tape 600.

[0030] S4: Interlayer composite and overall fixation: The drainage layer 100 with the heating layer 300 and the prepared reinforcing layer 200 are accurately stacked in alignment. Then, an industrial multi-needle sewing machine is used, and the sewing thread 500, specifically a high-strength polyester sewing thread in this embodiment, is used to stitch and fix the three-layer structure as a whole by lockstitch. When sewing, the stitch path strictly avoids the body of the carbon fiber heating wire 310 to ensure that the minimum distance between the stitch edge and the carbon fiber heating wire edge is not less than 3 mm.

[0031] S5: Integrate the temperature control module: The temperature sensor 701 is set at a predetermined position on the reinforcing layer 200 and fixed with graphene conductive adhesive. And complete the electrical connection and waterproof sealing treatment of its electrode transition section with the heating layer 300 and the sensor lead wire.

[0032] S6: Quality inspection: Conduct a comprehensive inspection on the finished product for appearance, dimensions, drainage performance (GB / T 17633), heating performance (heating curve, surface temperature uniformity), mechanical properties (tensile strength in GB / T 15788), and electrical safety performance (insulation resistance, withstand voltage).

[0033] Example 2: Refer to Figure 7 , this example aims to elaborate in detail the application of a composite temperature-controlled drainage geotextile described in the present invention in the roadbed of highways in cold regions, which can prevent frost damage, improve the hydrothermal conditions, and enhance the overall performance of the roadbed in a complex roadbed structure.

[0034] The construction method of laying the composite temperature-controlled drainage geotextile provided by the present invention in the roadbed of highways in cold regions includes the following steps: S1: Treatment of the roadbed 801, construction of the gravel layer 802, and preliminary monitoring layout Treatment of the roadbed 801: Use a heavy roller to compact the original soil or replaced soil of the roadbed in layers, and the thickness of the loose paving for each layer of compaction is determined according to the results of soil tests. Operate according to the compaction process specified in the "Technical Specification for Highway Subgrade Construction" (JTG / T 3610) to ensure that the dry density after compaction of each layer reaches the specified compaction degree of the design requirements. After compaction is completed, finely level the top surface of the roadbed, and the allowable deviations of its flatness and elevation meet the specification requirements, providing a qualified supporting foundation for the laying of the gravel layer 802.

[0035] Laying the gravel layer 802: Uniformly lay the gravel layer 802 on the top surface of the qualified roadbed. The gravel material is selected as natural gravel or crushed stone with good gradation, hard texture, and high compressive strength. Its maximum particle size is controlled within 40 mm, and the minimum particle size is not less than 15 mm to ensure good porosity and water permeability within the layer. The thickness of the gravel layer 802 after compaction is controlled between 60 cm and 80 cm.

[0036] S2: Laying and system construction of the first composite temperature-controlled drainage geotextile layer 803 Laying the geotextile: On the upper surface of the compacted and leveled gravel layer 802, fully lay the first composite temperature-controlled drainage geotextile described in the present invention. During laying, ensure that the drainage layer 100 of the geotextile faces upward and the reinforcement layer 200 faces downward. The geotextile should be smooth, without wrinkles or air pockets, and in full contact with the gravel layer 802.

[0037] Slope extension and lap: The first composite temperature-controlled drainage geotextile layer 803 should be continuously laid and extended to the outer edge of the slope surface on both sides of the road, with an extension length of not less than 60 cm, so as to divert the collected water away from the main structure of the roadbed and discharge it through evaporation or into the slope drainage system. The lap width between adjacent geotextiles is not less than 30 cm.

[0038] Temperature control system connection: The electrode transition section of the heating layer 300 of the first composite temperature control drainage geotextile layer 803 and the power input line of the temperature control module are safely connected to the preset energy storage structure on the road side through a waterproof connector and a special armored cable. As a preferred technical solution, the energy storage structure includes a battery pack 809, which is connected to a controller 810 through a line, and the controller is connected to a power generation component, which is a photovoltaic component 811 and a fan component 812.

[0039] S3: Construction and monitoring layout of filler layer 804 On the first composite temperature-control drainage geotextile layer 803, a filler layer 804 is evenly laid. The filler is coarse sand with a diameter of 2.0 mm to 4.0 mm. The thickness of the filler layer 804 after compaction is controlled to be 30 cm to 50 cm.

[0040] S4: Cement stabilized gravel base 805 construction and monitoring layout On the filler layer 804, a cement stabilized crushed stone base layer 805 is laid. The material gradation, cement dosage and construction process shall all comply with the requirements of the "Technical Specifications for Highway Pavement Base Construction" (JTG / T F20). The thickness of the base layer after compaction is controlled to be 30cm to 50cm.

[0041] S5: Laying and system construction of the second composite temperature-controlled drainage geotextile layer 806 Geotextile laying: Lay the second composite temperature-control drainage geotextile layer 806 on the top surface of the cement-stabilized gravel base 805. The laying method, drainage layer orientation, slope extension requirements and overlap treatment are the same as the laying of the first composite temperature-control drainage geotextile layer 803 in S2.

[0042] Functional positioning: In addition to having the same drainage, reinforcement and active temperature control functions as the first composite temperature-control drainage geotextile layer 803, the second composite temperature-control drainage geotextile layer 806 has a more direct function of preventing surface water from seeping into the base layer and eroding the base layer, and can effectively prevent the "mud-turning" phenomenon caused by the upwelling of water after the base layer melts in the spring, while providing a certain thermal insulation effect on the cement-stabilized gravel base layer.

[0043] Temperature control system connection: Similarly, the heating system and temperature control module of the second composite temperature control drainage geotextile layer 806 are connected to the energy storage structure. The temperature control systems of the two geotextile layers can be controlled independently or in a linkage manner.

[0044] S6: Construction of pavement layer 807 On the second composite temperature-controlled drainage geotextile layer 806, an asphalt concrete pavement layer 807 is laid. The total thickness of the pavement layer 807 is controlled within 10 cm to 20 cm and usually includes a bottom layer, a middle layer, and a top layer. The road surface should be provided with a 2%-3% cross slope from the road center line to both side slopes to facilitate the rapid drainage of road surface water.

[0045] S7: Auxiliary drainage facilities On both sides of the laying range of the gravel layer 802, drainage ditches 808 are longitudinally excavated along the road. The size and slope of the drainage ditches are determined according to the designed drainage volume. The drainage ditches 808 are used to collect and drain the water discharged from the composite temperature-controlled drainage geotextiles extending from the gravel layer 802 and the side slopes, ensuring that the main structure of the roadbed is in a relatively dry state.

[0046] S8: Operation and effect monitoring Intelligent temperature control strategy: The start-stop and heating power of the two-layer heating system are intelligently regulated through the temperature control module integrated in the geotextile. In winter, the first composite temperature-controlled drainage geotextile layer 803 is preferentially started to conduct basic heat preservation for the deep roadbed. When the temperature drops suddenly or the upper structure faces the risk of freezing, the heating power of the second composite temperature-controlled drainage geotextile layer 806 is started or increased.

Claims

1. A composite temperature-controlled drainage geotextile, characterized in that, include: (a) a drainage layer (100), wherein the drainage layer is formed by biaxial warp knitting a wicking fiber bundle (110) with a special cross-section and a polypropylene reinforcement fiber bundle (120) to form a three-dimensional water-conducting structure with capillary water-conducting channels; (b) a reinforcing layer (200), the reinforcing layer being arranged on one side of the drainage layer (100) and being formed into a grid structure having high tensile strength by a hot-melt bonding process using ultra-high molecular weight polyethylene fibers; (c) a heating layer (300), the heating layer comprising a plurality of carbon fiber heating wires (310) arranged in parallel and in a serpentine shape, the carbon fiber heating wires (310) being electrically connected in series and embedded in a quilted channel (400) between the drainage layer (100) and the reinforcement layer (200), the width of the quilted channel (400) being 1.2 to 1.5 times the diameter of the carbon fiber heating wires (310); (d) a temperature control module, the temperature control module being electrically connected to a power supply circuit of the heating layer (300) and being used to monitor the temperature and control the heating power of the heating layer (300), the temperature control module comprising: at least two temperature sensors (701) laid on the reinforcement layer (200) at predetermined intervals, and a temperature control device (702), the temperature control device (702) being electrically connected to a power supply circuit of the heating layer (300) and being configured to dynamically adjust the power of the heating layer (300) according to a preset soil freezing temperature threshold.

2. The composite temperature-controlled drainage geotextile according to claim 1, characterized in that: The monofilament cross section of the shaped cross-section wicking fiber bundle (110) has at least three radially extending capillary protrusions (111), and longitudinal drainage channels (112) with a width of 3-5 μm are formed between adjacent capillary protrusions (111).

3. A composite temperature-controlled drainage geotextile according to claim 2, characterized in that: The diameter of the single filament in the profiled cross-section wicking fiber bundle (110) is 10-15 μm, and each bundle contains 400-600 fibers; the warp density of the drainage layer (100) is 50-70 fibers / cm, and the weft density is 40-60 fibers / cm; the specification of the polypropylene reinforced fiber bundle (120) is 4400D, and the weaving ratio of the polypropylene reinforced fiber bundle (120) to the profiled cross-section wicking fiber bundle (110) is 2:1 to 4:1, and the swing angle of the guide needle during the biaxial warp knitting process is 35°-45°.

4. A composite temperature-controlled drainage geotextile according to claim 1, characterized in that: The quilted channel (400) is formed by a lockstitch quilting process, and the spacing between adjacent quilted channels (400) is 5-20 cm; the carbon fiber heating wire (310) is passed through the quilted channel (400) according to a preset curved path, and its electrode transition section (510) is fixed by a double-sided conductive tape (600) with a peel strength of not less than 5 N / cm.

5. A composite temperature-controlled drainage geotextile according to claim 1, characterized in that: The carbon fiber heating wire (310) comprises: A carbon fiber core (311) is formed by a bundle of at least 3,000 carbon fiber monofilaments; An inner insulating layer (312), coated on the outer surface of the carbon fiber core (311), is made of a polyimide film or ceramic silicone rubber with a temperature resistance level of not less than 200°C, has a thickness of 0.1-0.3 mm, and a breakdown voltage of not less than 3 kV / mm; The electromagnetic shielding layer (313) covers the outer surface of the inner insulation layer (312) and is composed of a silver-plated aramid braided layer or graphene-modified non-woven fabric with a surface resistivity not greater than 1×10²Ω / sq, and its braiding density is not less than 90%; The outer protective layer (314) covers the outer surface of the electromagnetic shielding layer (313) and is made of fluororubber or modified polyurethane elastomer, with a thickness of 0.5-1.0mm and a flexural resistance of not less than 500,000 times.

6. A composite temperature-controlled drainage geotextile according to claim 1, characterized in that: The heating layer (300) adopts a segmented power supply design, where the carbon fiber heating wire (310) constituting the heating layer (300) is organized into several independent heating units, and the length of each independent heating unit is 5-20m and is connected to two spaced power supply wires; the working voltage of each independent heating unit is not greater than 48V DC, and the total resistance difference between independent heating units is not greater than 5%.

7. The composite temperature-controlled drainage geotextile according to claim 1, wherein: The temperature control device (702) is further configured to: set the soil freezing temperature threshold as a parameter that can be adjusted according to actual working conditions and anti-freezing objectives, and dynamically adjust the heating power of the heating layer (300) based on this threshold and the real-time monitoring of the temperature sensor (701).

8. A composite temperature-controlled drainage geotextile according to claim 1, characterized in that: The temperature sensor (701) is fixed to the reinforcing layer (200) through flexible graphene conductive adhesive, and the peel strength of the flexible graphene conductive adhesive is not less than 8N / cm.

9. A composite temperature-controlled drainage geotextile according to claim 1, characterized in that: The drainage layer (100), the reinforcing layer (200), and the heating layer (300) embedded between the two are fixed by a lockstitch along a preset stitching path with a suture (500) to form an integral composite structure.

10. A composite temperature-controlled drainage geotextile according to claim 9, characterized in that: The stitching path avoids the area directly penetrated by the carbon fiber heating wire (310), ensuring that the stitch is not less than 3mm away from the edge of the carbon fiber heating wire (310).

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