A drainage structure under a pavement

Abstract

The utility model discloses a kind of drainage structures under pavement, comprising: drainage groove extending along longitudinal direction, located below pavement, cross section is V-shaped structure, the groove bottom of the drainage groove is equipped with longitudinal slope's flow guide ditch and transverse slope's salt collection area, the salt collection area is spaced apart and arranged several sedimentation tanks in longitudinal direction, the fixed salt collection box's magnetic suction socket of the groove inner wall of the drainage groove is equipped with corresponding the sedimentation tank position;Composite salt separation layer is set between the drainage groove and the pavement, the composite salt separation layer includes HDPE film from below to above, bentonite blanket, geotextile, the laying width of the HDPE film and bentonite blanket is 1.2-1.8 times of the width of the drainage groove top groove, and the geotextile is fully covered below the pavement.This multilayer composite design prevents the erosion of pavement by salt and alkali in all directions, greatly reduces the probability of occurrence of reverse alkali phenomenon, and maintains the beauty and function of pavement.

Description

Technical Field

[0001] This utility model relates to the field of drainage technology under paved surfaces, and in particular to a drainage structure under paved surfaces. Background Technology

[0002] In the design of paving surfaces for various landscapes and buildings, ensuring good drainage performance and effectively preventing efflorescence are crucial. Currently, common drainage structures under paving surfaces have many problems that need improvement. Traditional drainage channels are mostly simple straight channel designs, which are significantly inefficient in terms of drainage. When encountering heavy rainfall or other water sources, due to the guiding structure, water tends to accumulate in local areas, making it difficult to drain quickly and smoothly.

[0003] During the hydration process, building materials such as cement release large amounts of alkaline components such as free calcium and calcium hydroxide. These components are easily dissolved in water and carried to the surface of the pavement. They then react chemically with carbon dioxide in the air to form white crystalline substances such as calcium carbonate, a phenomenon known as efflorescence. Current technologies for addressing this problem mostly employ single waterproofing or isolation measures, with unsatisfactory results. Furthermore, traditional drainage structures are almost entirely lacking in salt collection and treatment capabilities. Over time, the accumulation of salt in the soil causes serious damage to plant growth and the pavement structure itself. Utility Model Content

[0004] The purpose of this utility model is to provide a drainage structure under the pavement to solve one or more technical problems existing in the prior art, and at least provide a beneficial option or create conditions.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows:

[0006] This utility model provides a drainage structure under the pavement, including:

[0007] The drainage ditch extends longitudinally and is located below the paved surface. It has a V-shaped cross-section. The bottom of the drainage ditch is provided with a longitudinally sloping guide channel and a transversely sloping salt collection area. The salt collection area is provided with several sedimentation tanks at intervals in the longitudinal direction. The sedimentation tanks are filled with calcium ion adsorbent. The inner wall of the drainage ditch is provided with magnetic insertion ports for fixing salt collection boxes corresponding to the positions of the sedimentation tanks.

[0008] A composite salt barrier layer is disposed between the drainage ditch and the paving surface. The composite salt barrier layer includes, from bottom to top, an HDPE membrane, a bentonite blanket, and a geotextile. The laying width of the HDPE membrane and the bentonite blanket is 1.2-1.8 times the width of the top opening of the drainage ditch. The geotextile completely covers the bottom of the paving surface.

[0009] This technical solution employs a V-shaped drainage channel design, combined with a longitudinally sloping guide ditch at the bottom, significantly improving drainage efficiency. The unique shape of the V-shaped channel allows water to naturally converge towards the bottom under gravity and flow rapidly longitudinally along the guide ditch. Compared to traditional straight-channel drainage structures, it offers faster drainage, effectively preventing water accumulation on pavement due to poor drainage, extending the service life of the pavement, and reducing erosion and damage to the pavement materials caused by water accumulation.

[0010] Furthermore, a horizontally sloping salt collection area is set at the bottom of the drainage ditch, and several sedimentation tanks are distributed longitudinally at intervals. The tanks are filled with calcium ion adsorbent, which can effectively adsorb and precipitate salts in the water flow. The composite salt barrier layer comprehensively prevents the erosion of the pavement by salt and alkali, greatly reduces the probability of efflorescence, and maintains the aesthetics and functionality of the pavement.

[0011] As an extension of the above solution: a magnetic interface is provided on one side of the salt collection box, and the salt collection box is fixed on the sedimentation tank by magnetic attraction between the magnetic interface and the magnetic plug.

[0012] In this extended solution, when the salt collection box needs to be installed, the magnetic interface on one side of the salt collection box is aligned with the magnetic socket on the drainage trough. The magnetic attraction between the neodymium iron boron permanent magnet and the ferromagnetic metal sheet ensures a tight fit, thus fixing the salt collection box to the sedimentation tank. During drainage, water containing salt flows into the sedimentation tank. The filter element inside the salt collection box filters and adsorbs the salt, while the magnetic attraction generates a fixing force that resists the impact of the water flow on the salt collection box, ensuring its stable position. When maintenance is required, the magnetic force is overcome by external force to remove the salt collection box from the magnetic socket. After replacing the filter element or cleaning the salt collection box, it can be re-fixed using the magnetic attraction. This embodiment of the salt collection box offers convenient and efficient installation, easy maintenance and replacement, and a stable and reliable fixation.

[0013] As an extension of the above scheme: the salt collection box is equipped with three filter layers, including a cation exchange resin layer, an anion exchange fiber layer, and a pH indicator silica gel layer.

[0014] During operation, water containing salt enters the salt collection box and first flows through the cation exchange resin layer. The H⁺ in the resin reacts with cations such as Ca²⁺ and Mg²⁺ in the water, adsorbing the metal cations onto the resin surface. Next, the water flows into the anion exchange fiber layer, where the OH⁻ in the fibers combines with anions such as Cl⁻ and SO₄²⁻, further removing anions from the water. Finally, it passes through the pH indicator silica gel layer. If the water's pH is normal, the silica gel layer remains green. If the first two filter layers become saturated and ineffective, resulting in salt residue or water pollution, the silica gel layer will change color to issue a warning. When maintenance personnel observe a color change, they can determine that the filter needs replacement to ensure the continued effectiveness of the desalination function.

[0015] As an extension of the above solution: a water guide strip is provided on the outer side of the drainage ditch, and a transverse opening is provided on the top of the drainage ditch. The water guide strip extends from the edge of the composite salt barrier layer to the transverse opening. Of the water blocked by the composite salt barrier layer, a small amount of water seeping from the edge will be captured by the water guide strip and flow towards the transverse opening, merging with the main flow in the drainage ditch before being discharged along the guide channel.

[0016] As an extension of the above solution, the transverse groove is equipped with hydrophobic filter cotton. The hydrophobic filter cotton is a three-dimensional mesh structure made of polyester fiber (PET) or polypropylene (PP), with a fiber diameter of 10-20μm to ensure pore connectivity. An annular groove with a width of 5-8mm and a depth of 3mm is pre-set on the inner side of the transverse groove. The edge of the hydrophobic filter cotton is embedded in the groove, and the gap is sealed with butyl waterproof tape. The filter cotton adheres tightly to the inner wall of the groove without wrinkles, ensuring that all water flow must be filtered by the filter cotton before entering the drainage tank. When water in the water guide belt flows towards the transverse groove, it first contacts the hydrophobic filter cotton. The three-dimensional mesh structure of the hydrophobic filter cotton, through mechanical interception, traps impurities with a particle size ≥5μm in the water, preventing them from entering the drainage tank.

[0017] As an extension of the above solution: the water guide strip is filled with graded crushed stone. The water guide strip is filled with graded crushed stone with a particle size range of 2-5mm, which can ensure rapid water penetration and filter soil particles to avoid clogging.

[0018] As an extension of the above solution: the composite salt barrier layer has a guide hole at the top slot of the drainage trough, the guide hole is connected to a guide short pipe through a heat-sealed pressure ring, and the guide short pipe extends into the drainage trough.

[0019] In this extended design, water accumulated above the composite salt barrier layer converges under gravity through the guide holes and enters the guide pipe. The combination of the guide holes and the guide pipe directs the water above the composite salt barrier layer into the drainage trough, preventing water from spreading on the surface of the salt barrier layer and forming localized water accumulation.

[0020] As an extension of the above solution: a filter screen is installed at the top inlet of the guide pipe, and graded crushed stone covers the inlet. When the accumulated water above the composite salt barrier layer flows into the guide pipe, it first comes into contact with the graded crushed stone around the inlet. The water undergoes preliminary filtration through the pores between the graded crushed stone; larger impurities are blocked above the crushed stone layer, while smaller water particles continue to permeate downwards. After being filtered by the graded crushed stone, the water reaches the filter screen, which further intercepts any remaining fine impurities in the water, ensuring that the water entering the guide pipe is clean and preventing impurities from accumulating and clogging the pipe. At the same time, the buffering effect of the graded crushed stone allows the water to pass smoothly through the filter screen into the guide pipe, ensuring efficient drainage.

[0021] As an extension of the above solution, a capillary blocking strip is provided on the outer side of the drainage channel. This capillary blocking strip includes a lower hydrophobic zone and an upper hydrophilic zone. The lower hydrophobic zone is a silane emulsion coating, and the upper hydrophilic zone is a sodium polyacrylate superabsorbent resin layer. The silane emulsion coating of the lower hydrophobic zone significantly reduces the surface energy of the soil pores, disrupting the upward force of capillary water and creating a barrier at the hydrophobic zone. This reduces the upward height of capillary water by more than 80% compared to traditional unblocked structures, thus reducing the possibility of salt and alkali migrating to the pavement surface with moisture from the source.

[0022] As an extension of the above solution: the upper hydrophilic band is embedded with water-conducting fiber bundles. One end of each fiber bundle is embedded in a sodium polyacrylate superabsorbent resin layer, and the other end extends into the drainage channel. After the sodium polyacrylate superabsorbent resin layer absorbs water, the water forms a gel state inside the resin. The water-conducting fiber bundles utilize the surface tension generated by the capillary pores between the fibers to adsorb free water from the resin gel into the fiber bundles. Through continuous capillary action, the water is transported axially along the fiber bundles, flowing from the end embedded in the resin layer to the end extending into the drainage channel, and finally dripping into the guide channel of the drainage channel, where it is discharged with the water flow. During this process, the fiber bundles continuously reduce the load on the resin layer, ensuring that the resin maintains a high water absorption capacity, while preventing the accumulation and crystallization of salt and alkali ions caused by long-term water retention in the resin layer. Compared to resins without fiber bundle structures, the service life is extended by 1-2 times, avoiding the risk of capillary water breakthrough due to saturation failure. Attached Figure Description

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0024] Figure 1 This is a schematic diagram of the drainage structure in the embodiment;

[0025] Figure 2 This is a top view of the drainage trough in an embodiment;

[0026] In the attached diagram: 10: Pavement surface, 100: Drainage trough, 110: Diversion ditch, 120: Salt collection area, 130: Sedimentation tank, 140: Salt collection box, 141: Magnetic interface, 150: Water guide strip, 160: Horizontal groove, 170: Capillary blocking strip, 171: Lower hydrophobic strip, 172: Upper hydrophilic strip, 180: Water guiding and limiting bundle, 200: Composite salt barrier layer, 210: HDPE membrane, 220: Bentonite blanket, 230: Geotextile, 240: Diversion hole, 250: Diversion short pipe, 251: Filter screen. Detailed Implementation

[0027] This section will describe in detail the specific embodiments of the present utility model. The preferred embodiments of the present utility model are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present utility model, but they should not be construed as limiting the scope of protection of the present utility model.

[0028] In the description of this utility model, it should be understood that the directional descriptions, such as up, down, front, back, left, right, etc., indicate the directional or positional relationship based on the directional or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0029] In the description of this utility model, if there are words such as "several", they mean one or more, "multiple" means two or more, "greater than", "less than", "exceeding" etc. are understood to exclude the number itself, and "above", "below", "within" etc. are understood to include the number itself.

[0030] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0031] Reference Figures 1 to 2 The following are several embodiments of a drainage structure under a paved surface according to the present invention.

[0032] In some embodiments, such as Figures 1 to 2 As shown, this utility model provides a drainage structure under the pavement, comprising:

[0033] A longitudinally extending drainage ditch 100 is located below the paved surface 10 and has a V-shaped cross-section. The bottom of the drainage ditch 100 is provided with a longitudinally sloping guide channel 110 and a transversely sloping salt collection area 120. The salt collection area 120 is provided with several sedimentation tanks 130 at intervals in the longitudinal direction. The sedimentation tanks 130 are filled with calcium ion adsorbent. The inner wall of the drainage ditch 100 is provided with magnetic insertion ports for fixing salt collection boxes 140 corresponding to the positions of the sedimentation tanks 130.

[0034] A composite salt barrier layer 200 is disposed between the drainage ditch 100 and the paving surface 10. The composite salt barrier layer 200, from bottom to top, includes an HDPE membrane 210, a bentonite blanket 220, and a geotextile 230. The laying width of the HDPE membrane 210 and the bentonite blanket 220 is 1.2-1.8 times the width of the top opening of the drainage ditch 100. The geotextile 230 completely covers the area below the paving surface 10. For example, if the width of the top opening of the drainage ditch is 1 meter, the laying width of the HDPE membrane and the bentonite blanket should be between 1.2 and 1.8 meters to ensure sufficient coverage of areas around the drainage ditch that may experience salt and alkali infiltration. The geotextile must completely cover the area below the paving surface, and its edge should extend at least 20-30 cm beyond the edge of the paving surface to ensure comprehensive protection of the entire paving surface.

[0035] The drainage trough extends longitudinally and has a V-shaped cross-section. This V-shaped structure guides water flow to the bottom of the trough quickly, improving drainage efficiency. The guide channel at the bottom of the trough has a longitudinal slope, generally recommended to be between 1% and 3%. This slope ensures that water flows continuously and stably towards the drainage outlet under gravity. The salt collection area has a transverse slope, typically around 1%, which directs saline water towards the sedimentation tank. Sedimentation tanks are spaced longitudinally, with the spacing adjusted according to the actual drainage area and expected salt content, generally between 5 and 10 meters. The calcium ion adsorbent filling the sedimentation tanks can be made of materials with good ion exchange properties, such as zeolite. Its filling height should reach approximately 2 / 3 of the sedimentation tank depth to ensure sufficient adsorption. Magnetic connectors are used to fix the salt collection boxes. These connectors should have sufficient magnetic strength to withstand the force of water flow impact, ensuring the salt collection boxes are firmly fixed. For example, magnetic materials with a magnetic attraction force of at least 50N can be used to make the connectors.

[0036] The composite salt barrier layer consists of an HDPE membrane, bentonite blankets, and geotextile. The HDPE membrane is typically 0.5-1.5 mm thick and has extremely low permeability, effectively preventing underground salt and alkali substances from rising with moisture. The bentonite blankets contain sodium-based bentonite, which rapidly expands upon contact with water to form a dense, waterproof layer, further enhancing the salt barrier effect. The geotextile, with a specification of 200-500 g / m², possesses excellent filtration and reinforcement properties, preventing fine particles from clogging drainage channels while simultaneously stabilizing the entire composite salt barrier layer structure. This multi-layered composite design comprehensively prevents salt and alkali erosion of the pavement surface, significantly reducing the probability of efflorescence and maintaining the aesthetics and functionality of the pavement.

[0037] In this embodiment, the drainage channel adopts a V-shaped structure design, combined with a guide channel with a longitudinal slope at the bottom of the channel, which can significantly improve drainage efficiency. The unique shape of the V-shaped channel allows water to naturally converge towards the bottom of the channel under the action of gravity and flow rapidly longitudinally along the guide channel. Compared with the traditional straight channel drainage structure, its drainage speed is faster, which can effectively avoid the problem of water accumulation on the pavement due to poor drainage, extend the service life of the pavement, and reduce the erosion and damage to the pavement materials caused by water accumulation.

[0038] The drainage ditch features a horizontally sloping salt collection area at its bottom, with several sedimentation tanks spaced longitudinally. These tanks are filled with calcium ion adsorbent, effectively adsorbing and precipitating salts from the water flow. Furthermore, a salt collection box, secured by a magnetic connector, contains a three-layer filter: a cation exchange resin layer, an anion exchange fiber layer, and a pH-indicating silica gel layer, further exchanging, filtering, and monitoring salts. This embodiment effectively reduces salt accumulation in the soil, minimizing the potential damage to drainage structures and paving surfaces caused by salt.

[0039] In some embodiments, such as Figures 1 to 2 As shown, a magnetic interface 141 is provided on one side of the salt collection box 140. The salt collection box 140 is fixed on the sedimentation tank 130 by magnetic attraction between the magnetic interface 141 and the magnetic insertion port.

[0040] In this embodiment, the magnetic interface on one side of the salt collection box uses a neodymium iron boron permanent magnet as the core magnetic element, and its surface is electroplated with nickel to improve corrosion resistance and service life. A ferromagnetic metal sheet is correspondingly installed at the magnetic insertion port on the inner wall of the drainage trough. The metal sheet is fixed to the inner wall of the drainage trough by welding or bolts to ensure a secure installation. A positioning boss with a height of 2-3mm is provided on the edge of the magnetic insertion port to accurately position the salt collection box and prevent installation misalignment. Those skilled in the art will understand that, due to the long-term presence of moisture in the drainage trough, strict anti-corrosion treatment can be applied to the permanent magnet of the magnetic interface and the metal sheet of the magnetic insertion port. In addition to the electroplating of nickel on the surface of the permanent magnet, the metal sheet of the magnetic insertion port can be coated with an epoxy resin coating to prevent rusting and affecting the magnetic attraction effect. Simultaneously, a rubber sealing ring should be installed on the outside of the magnetic interface of the salt collection box. When magnetically fixed, the sealing ring is compressed to prevent moisture from seeping into the magnetic element and causing damage.

[0041] When installing the salt collection box, align the magnetic connector on one side of the salt collection box with the magnetic socket on the drainage trough. The magnetic attraction between the neodymium iron boron permanent magnet and the ferromagnetic metal sheet ensures a tight fit, fixing the salt collection box in place on the sedimentation tank. During drainage, salty water flows into the sedimentation tank. The filter element inside the salt collection box filters and adsorbs the salt, while the magnetic attraction resists the impact of the water flow, ensuring its stability. For maintenance, simply overcome the magnetic force to remove the salt collection box from the magnetic socket, replace the filter element or clean the box, and then re-secure it using the magnetic connection. This embodiment of the salt collection box offers convenient and efficient installation, easy maintenance and replacement, and a secure and reliable fixation.

[0042] In some embodiments, the salt collection box is provided with three filter layers, which include a cation exchange resin layer, an anion exchange fiber layer, and a pH indicator silica gel layer.

[0043] The cation exchange resin layer uses 001×7 strong acid styrene-based cation exchange resin with a particle size range of 0.315-1.25 mm and an exchange capacity ≥4.5 mmol / g. The thickness of this resin layer is 1 / 3 of the height of the salt collection box, typically 8-12 cm, and the packing density is controlled at 0.7-0.8 g / cm³ to ensure sufficient contact between the water and the resin during water flow, achieving efficient exchange and adsorption of cations such as Ca²⁺ and Mg²⁺ in the water.

[0044] The anion exchange fiber layer is made of polyvinylpyridine-based anion exchange fiber with a diameter of 20-50 μm, a specific surface area ≥100 m² / g, and an exchange capacity ≥2.0 mmol / g. The layer is laid to a thickness of 5-8 cm, using a loose filling method to retain 15%-20% porosity, ensuring smooth water flow while effectively capturing anions such as Cl⁻ and SO₄²⁻.

[0045] The pH-indicating silica gel layer is made of bromocresol green indicator loaded on a silica gel carrier, with particle diameters of 2-5 mm and thicknesses of 3-5 cm. It turns yellow when in contact with water with a pH < 6, green when the pH is between 6 and 8, and blue when the pH is > 8. The color change provides a direct indication of the water's acidity or alkalinity and indirectly reflects the saturation level of the first two filter layers. Saturation of the filter layers may lead to abnormal pH levels in the water.

[0046] During operation, water containing salt enters the salt collection box and first flows through the cation exchange resin layer. The H⁺ in the resin reacts with cations such as Ca²⁺ and Mg²⁺ in the water, adsorbing the metal cations onto the resin surface. Next, the water flows into the anion exchange fiber layer, where the OH⁻ in the fibers combines with anions such as Cl⁻ and SO₄²⁻, further removing anions from the water. Finally, it passes through the pH indicator silica gel layer. If the water's pH is normal, the silica gel layer remains green. If the first two filter layers become saturated and ineffective, resulting in salt residue or water pollution, the silica gel layer will change color to issue a warning. When maintenance personnel observe a color change, they can determine that the filter needs replacement to ensure the continued effectiveness of the desalination function.

[0047] In some embodiments, such as Figure 1 As shown, a water guide strip 150 is provided on the outer side of the drainage ditch 100, and a transverse opening 160 is provided on the top of the drainage ditch 100. The water guide strip 150 extends from the edge of the composite salt barrier layer 200 to the transverse opening 160. In some preferred embodiments, the water guide strip is filled with graded crushed stone. The water guide strip is filled with graded crushed stone with a particle size range of 2-5mm, which can ensure rapid water penetration and filter soil particles to avoid clogging. The water guide strip is symmetrically arranged along the outer side of the drainage ditch, and the number of sides is determined according to the drainage requirements. It extends outward from the edge of the composite salt barrier layer, and the extension length is 1 / 2 of the width of the drainage ditch opening (i.e., 0.1-0.4 times the width of the opening). When laid, a slope of 0.5%-1% is formed, and the slope direction is consistent with the slope direction of the drainage ditch guide channel to ensure that water flows to the transverse opening.

[0048] The transverse sluices are installed every 1-2 meters along the longitudinal direction of the drainage channel, with the spacing increased to 0.5-1 meter in areas with significant terrain undulations, ensuring that water within the water-conducting strip can promptly flow into the drainage channel. A small amount of water seeping from the edges of the composite salt-barrier layer is captured by the graded gravel in the water-conducting strip and flows towards the transverse sluices, merging with the main flow in the drainage channel before being discharged along the diversion channel. During this process, the graded gravel in the water-conducting strip filters out soil particles from the water.

[0049] In some preferred embodiments, the transverse groove is provided with hydrophobic filter cotton. The hydrophobic filter cotton is a three-dimensional mesh structure made of polyester fiber (PET) or polypropylene (PP), with a fiber diameter of 10-20μm to ensure pore connectivity. An annular groove with a width of 5-8mm and a depth of 3mm is pre-set on the inner side of the transverse groove. The edge of the hydrophobic filter cotton is embedded in the groove, and the gap is sealed with butyl waterproof tape. The filter cotton fits tightly against the inner wall of the groove without wrinkles, ensuring that all water flow must be filtered by the filter cotton before entering the drainage tank. When water in the water guide belt flows towards the transverse groove, it first contacts the hydrophobic filter cotton. The three-dimensional mesh structure of the filter cotton, through mechanical interception, traps impurities with a particle size ≥5μm in the water, preventing them from entering the drainage tank.

[0050] In some embodiments, such as Figure 1 As shown, the composite salt barrier layer 200 has a guide hole 240 at the top slot position corresponding to the drainage trough 100. The guide hole 240 is connected to the guide short pipe 250 through a heat-sealed pressure ring. The guide short pipe 250 extends into the drainage trough 100.

[0051] In this embodiment, water accumulated above the composite salt barrier layer converges under gravity through the guide holes and enters the guide pipe. Due to the heat-sealing between the pressure ring, the HDPE membrane, and the guide pipe, water cannot penetrate from the edge of the guide holes to below the HDPE membrane, preventing salt ions from migrating with the water; instead, it flows along the inner cavity of the guide pipe. The guide pipe directs the water flow to the guide channel of the drainage trough, and the water is discharged longitudinally along the guide channel. The combination of the guide holes and the guide pipe can directionally guide the water above the composite salt barrier layer into the drainage trough, preventing water from spreading on the surface of the salt barrier layer and forming local water accumulation. Compared with a non-directional guide structure, the drainage efficiency above the composite salt barrier layer can be greatly improved, reducing the soaking time of water on the pavement base layer, reducing the risk of sanding and hollowing of the pavement surface, and protecting the structural integrity of the composite salt barrier layer.

[0052] In some embodiments, such as Figure 1 As shown, a filter screen 251 is installed at the top inlet of the guide pipe 250, and graded crushed stone covers the inlet. The filter screen is fixed to the top inlet of the guide pipe by stainless steel clamps, the diameter of which matches the outer diameter of the guide pipe. When the water above the composite salt barrier layer flows into the guide pipe, it first comes into contact with the graded crushed stone around the inlet. The water undergoes preliminary filtration through the pores between the graded crushed stone; larger impurities are blocked above the crushed stone layer, while smaller water particles continue to permeate downwards. After being filtered by the graded crushed stone, the water reaches the filter screen, which further intercepts the remaining fine impurities in the water, ensuring that the water entering the guide pipe is clean and preventing impurities from accumulating and clogging the pipe. At the same time, the buffering effect of the graded crushed stone allows the water to pass smoothly through the filter screen into the pipe, ensuring efficient drainage.

[0053] In some embodiments, such as Figure 1 As shown, a capillary blocking band 170 is provided on the outer side of the drainage channel 100. The capillary blocking band includes a lower hydrophobic band 171 and an upper hydrophilic band 172. The lower hydrophobic band 171 is a silane emulsion coating, and the upper hydrophilic band 172 is a sodium polyacrylate superabsorbent resin layer.

[0054] In this embodiment, the capillary blocking strip is continuously laid along the outside of the drainage channel, with the lower hydrophobic strip occupying 2 / 3 of the total depth and the upper hydrophilic strip occupying 1 / 3 of the total depth. The lower hydrophobic strip uses isobutyltriethoxysilane emulsion with a solid content of 30%-40%, a pH value of 6-8, and a viscosity (25℃) of 5-15 mPa·s. The upper hydrophilic strip uses granular sodium polyacrylate superabsorbent resin with a particle size of 0.1-1 mm, a water absorption ratio (deionized water) ≥300 g / g, and a gel strength ≥1000 Pa after water absorption to prevent deformation and loss under pressure. The pH value is 6-8, neutral to avoid affecting soil properties. Under the action of surface tension, capillary water in the soil moves upward along the pores. When it comes into contact with the lower hydrophobic strip, the silane emulsion coating makes the surface of the soil particles strongly hydrophobic, disrupting the continuous phase of capillary water. The water flow cannot form an effective upward force, and most of the capillary water is blocked below the hydrophobic strip. For a small amount of capillary water that breaks through the hydrophobic zone, it will be quickly absorbed by the sodium polyacrylate superabsorbent resin above. The sodium carboxylate groups in the resin molecular chain combine with water molecules to form hydrogen bonds, converting the water into a gel state and locking it inside the resin. The expanded resin will fill the pores of the surrounding soil, further preventing subsequent water penetration.

[0055] This embodiment significantly reduces the surface energy of soil pores through the silane emulsion coating of the lower hydrophobic zone, disrupting the upward force of capillary water and creating a barrier at the hydrophobic zone. This reduces the capillary water rise height by more than 80% compared to traditional unblocked structures, thereby reducing the possibility of salt and alkali migrating to the pavement surface with water from the source.

[0056] In some embodiments, such as Figure 1 As shown, the upper hydrophilic band 172 embeds a water-conducting fiber bundle 180. One end of the water-conducting fiber bundle 180 is embedded in a sodium polyacrylate superabsorbent resin layer, and the other end extends into the drainage channel 100. The water-conducting fiber bundle is made of modified polyester fiber bundle with a hydrophilic surface treatment. Each bundle consists of 50-100 fibers with a diameter of 20-50 μm, a bundle diameter of 0.5-1 mm, and a length equal to the sum of the thickness of the hydrophilic band and the thickness of the drainage channel wall plus 5-10 cm, ensuring that one end is embedded in the sodium polyacrylate superabsorbent resin layer and the other end enters the drainage channel. After the sodium polyacrylate superabsorbent resin layer absorbs water, the water forms a gel state inside the resin. The water-conducting fiber bundle utilizes the surface tension generated by the capillary pores between the fibers to adsorb the free water in the resin gel into the fiber bundle. Through continuous capillary action, the water is transported along the axial direction of the fiber bundle, flowing from the end embedded in the resin layer to the end extending into the drainage channel, and finally dripping into the guide channel of the drainage channel and being discharged with the water flow in the channel. During this process, the fiber bundles continuously reduce the load on the resin layer, ensuring that the resin maintains a high water absorption capacity while preventing the accumulation and crystallization of salt and alkali ions caused by long-term water retention in the resin layer. This extends the service life of resins without fiber bundle structures by 1-2 times and avoids the risk of capillary water breakthrough due to saturation failure.

[0057] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A drainage structure under a pavement surface, characterized in that, include: A longitudinally extending drainage ditch (100) is located below the paved surface (10) and has a V-shaped cross-section. The bottom of the drainage ditch (100) is provided with a longitudinally sloping guide channel (110) and a transversely sloping salt collection area (120). The salt collection area (120) is provided with several sedimentation tanks (130) spaced apart in the longitudinal direction. The sedimentation tanks (130) are filled with calcium ion adsorbent. The inner wall of the drainage ditch (100) is provided with a magnetic insertion port for fixing the salt collection box (140) corresponding to the position of the sedimentation tank (130). A composite salt barrier layer (200) is disposed between the drainage ditch (100) and the paving surface (10). The composite salt barrier layer (200) includes, from bottom to top, an HDPE membrane (210), a bentonite blanket (220), and a geotextile (230). The laying width of the HDPE membrane (210) and the bentonite blanket (220) is 1.2-1.8 times the width of the top opening of the drainage ditch (100). The geotextile (230) completely covers the bottom of the paving surface (10).

2. The drainage structure under the pavement according to claim 1, characterized in that: The salt collection box (140) is provided with a magnetic interface (141) on one side. The salt collection box (140) is fixed on the sedimentation tank (130) by magnetic attraction between the magnetic interface (141) and the magnetic plug.

3. The drainage structure under the pavement according to claim 2, characterized in that: The salt collection box (140) is equipped with a three-layer filter element, which includes a cation exchange resin layer, an anion exchange fiber layer, and a pH indicator silica gel layer.

4. The drainage structure under the pavement according to claim 1, characterized in that: The drainage trough (100) is provided with a water guide (150) on the outside and a transverse groove (160) on the top of the drainage trough (100). The water guide (150) extends from the edge of the composite salt barrier layer (200) to the transverse groove (160).

5. A drainage structure under a pavement as described in claim 4, characterized in that: The transverse groove (160) is provided with hydrophobic filter cotton.

6. The drainage structure under the pavement according to claim 4, characterized in that: The water guide strip (150) is filled with graded crushed stone.

7. The drainage structure under the pavement according to claim 1, characterized in that: The composite salt barrier layer (200) has a guide hole (240) at the top slot position corresponding to the drainage trough (100). The guide hole (240) is connected to a guide tube (250) through a heat-sealed pressure ring. The guide tube (250) extends into the drainage trough (100).

8. A drainage structure under a pavement according to claim 7, characterized in that: A filter screen (251) is provided at the top inlet of the guide tube (250), and graded crushed stone is covered around the inlet.

9. A drainage structure under a pavement surface according to claim 1, characterized in that: The outer side of the drainage channel (100) is provided with a capillary blocking band (170), which includes a lower hydrophobic band (171) and an upper hydrophilic band (172). The lower hydrophobic band (171) is a silane emulsion coating, and the upper hydrophilic band (172) is a sodium polyacrylate superabsorbent resin layer.

10. A drainage structure under a pavement according to claim 9, characterized in that: The upper hydrophilic band (172) is embedded with a water-conducting fiber bundle (180), one end of which is embedded in a layer of sodium polyacrylate superabsorbent resin, and the other end extends into the drainage groove (100).

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