High-speed rail salt-resistant water-blocking roadbed adopting coarse particle filler and construction method of high-speed rail salt-resistant water-blocking roadbed

Abstract

The invention relates to a high-speed rail salt-resistant water-blocking roadbed adopting coarse particle filler and a construction method thereof.The roadbed comprises a roadbed body, a cation exchange layer, a common A / B group filler layer, a rubble layer and a concrete cover layer which are sequentially stacked, a plurality of breathing holes are formed in the concrete cover layer, and each breathing hole communicates with the rubble layer; according to the invention, the cation exchange layer is arranged between the roadbed body and the common A / B group filler layer, so that cations of water in the high-speed railway roadbed in the cold region can be separated by using the cation exchange layer and then discharged from the breathing holes along with water vapor, thereby solving the salt expansion phenomenon of the roadbed and prolonging the service life of the roadbed.

Description

Technical Field

[0001] The present invention relates to the technical field of high - speed railway subgrades, and particularly relates to a high - speed railway anti - salt and water - blocking subgrade using coarse - grained fillers and a construction method thereof. Background Art

[0002] The subgrade is the foundation of the track or road surface, and is a geotechnical structure formed by excavation or filling. The main function of the subgrade is to provide necessary conditions for the laying of the track or road surface and the operation of trains or vehicles, and to bear the static and dynamic loads of the track and rolling stock or the road surface and traffic loads, and at the same time transmit and disperse the loads deep into the foundation. In the longitudinal section, the subgrade must ensure the elevation required by the line; in the plane, the subgrade is connected with bridges and tunnels to form a complete and through line. In civil engineering, the subgrade occupies an important position in terms of construction quantity, floor area and investment.

[0003] In the prior art, there are mainly two forms for high - speed railway subgrades in cold regions: one is to respectively arrange new - type nano - heat rods on both sides of the original subgrade to provide a new means for the anti - frost heaving design and frost heaving treatment of high - speed railway subgrades in seasonal frozen soil areas, and this technology does not change the original subgrade structure form; the other is to open holes in the original subgrade bed to increase the porosity of the subgrade and use the Poisson effect of the holes to relieve the frost heaving deformation of the subgrade. The defect of this technology is that it causes damage to the original subgrade structure and has an adverse impact on the long - term subgrade strength and durability. The above two technologies both have a certain degree of mitigation effect and design suggestions on the frost heaving diseases of high - speed railway subgrades in cold regions, but they do not solve problems such as the salt expansion phenomenon of high - speed railway subgrades in cold regions, resulting in subgrade deformation. Summary of the Invention

[0004] The present invention provides a high - speed railway anti - salt and water - blocking subgrade using coarse - grained fillers and a construction method thereof to solve the technical problems such as the deformation of the high - speed railway subgrade caused by the salt expansion phenomenon of the high - speed railway subgrade in cold regions.

[0005] The technical solution of the present invention to solve the above - mentioned technical problems is as follows:

[0006] A high - speed railway anti - salt and water - blocking subgrade using coarse - grained fillers includes a subgrade body, a cation exchange layer, a common A / B group filler layer, a gravel layer and a concrete cover layer which are stacked in sequence. A plurality of breathing holes are opened on the concrete cover layer, and each breathing hole communicates with the gravel layer.

[0007] The beneficial effect of the present invention is that by arranging a cation exchange layer between the subgrade body and the common A / B group filler layer, the cations of the water in the high - speed railway subgrade in cold regions can be separated by the cation exchange layer and discharged with the water vapor from the breathing holes, thereby solving the salt expansion phenomenon of the subgrade and improving the life of the subgrade.

[0008] On the basis of the above technical solutions, the present invention can also be improved as follows.

[0009] Further, the material of the cation exchange layer is cation exchange resin.

[0010] Further, a first composite waterproof geotextile is laid between the roadbed body and the cation exchange layer, a waterproof geomembrane is laid between the ordinary A / B group filler layer and the gravel layer, and a second composite waterproof geotextile is laid between the gravel layer and the concrete cover layer.

[0011] Further, the first composite waterproof geotextile, the waterproof geomembrane and the second composite waterproof geotextile are all composed of a plastic film as an anti-seepage base material and a non-woven fabric; wherein, the plastic film is polyethylene or polyvinyl chloride or HDPE film or LDPE film or EVA film; the non-woven fabric is polyester synthetic fiber or polypropylene synthetic fiber.

[0012] Further, the thickness ranges of the first composite waterproof geotextile, the waterproof geomembrane and the second composite waterproof geotextile are all 0.004m - 0.006m.

[0013] Further, the ordinary A / B group filler layer is A group high-quality railway roadbed filler and / or B group good railway roadbed filler.

[0014] Further, the roadbed body is a rammed plain soil layer.

[0015] Further, the filling thickness range of the gravel layer is 0.3m - 0.5m, and the gravel particle size range of the gravel layer is 8cm - 10cm.

[0016] Further, the thickness range of the concrete cover layer is 3cm - 8cm.

[0017] In order to solve the above technical problems, the present invention also provides a construction method for a high-speed railway anti-salt and water-blocking roadbed using coarse-grained fillers, and its specific technical content is as follows:

[0018] A construction method for a high-speed railway anti-salt and water-blocking roadbed using coarse-grained fillers, comprising the following steps:

[0019] S1. Construct the roadbed body by the replacement method;

[0020] S2. Fill the cation exchange layer on the roadbed body and compact the cation exchange layer firmly by the rolling and ramming method;

[0021] S3. Lay the ordinary A / B group filler layer on the cation exchange layer and compact the ordinary A / B group filler layer firmly by the rolling and ramming method;

[0022] S4. Lay a gravel layer on the ordinary A / B group filler layer and compact the gravel layer by rolling;

[0023] S5. Pour the concrete cover layer on the gravel layer and drill a plurality of breathing holes in the concrete cover layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of moisture migration in a high-speed railway anti-salt and water-blocking subgrade using coarse-grained fillers in summer in an embodiment of the present invention;

[0025] Figure 2 It is a schematic diagram of moisture migration in a high-speed railway anti-salt and water-blocking subgrade using coarse-grained fillers in winter in the present invention;

[0026] Figure 3 It is a schematic diagram of the structure of the ordinary A / B group filler layer, gravel layer and concrete cover layer in an embodiment of the present invention;

[0027] Figure 4 It is a schematic diagram of the structure of the subgrade of the prior art in an embodiment of the present invention;

[0028] Figure 5 It is a schematic diagram of the "pot lid effect" occurring in the subgrade of the prior art in summer and winter in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The principles and features of the present invention will be described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0030] As Figure 1 and Figure 2 shown, this embodiment provides a high-speed railway anti-salt and water-blocking subgrade using coarse-grained fillers, which sequentially includes a subgrade body, a cation exchange layer, an ordinary A / B group filler layer, a gravel layer, and a concrete cover layer from bottom to top. A plurality of breathing holes are opened in the concrete cover layer, and each breathing hole communicates with the gravel layer. The subgrade body is a compacted plain soil layer. In summer, it can make the summer steam water drain out of the subgrade along the breathing holes, reduce the water content in the upper layer of the subgrade, and thus weaken the frost heaving deformation of the subgrade. At the same time, the cation exchange layer isolates the sodium ions (Na+) in the water vapor and allows the Na+ to drain out of the subgrade along with the water vapor. When the subgrade is waterlogged in winter, the cation exchange layer isolates the sodium ions (Na+) in the accumulated water of the subgrade and allows the isolated sodium ions to flow out of the breathing holes through the accumulated water.

[0031] By arranging a cation exchange layer between the subgrade body and the ordinary A / B group filler layer in the present invention, it is possible to separate the cations of the moisture in the subgrade of the high-speed railway in cold regions by using the cation exchange layer and then discharge them from the breathing holes along with the water vapor, thereby solving the salt expansion phenomenon of the subgrade and improving the service life of the subgrade.

[0032] In some embodiments, the material of the cation exchange layer is cation exchange resin. Cation exchange resin is a high molecular compound with acidic exchange groups, usually sulfonic acid type or carboxylic acid type. When the resin contacts a solution containing cations, the active groups on the resin will dissociate to produce exchangeable cations (such as hydrogen ions H+). Cations in the solution (such as Na+, Ca 2 +, Mg2+, etc.) will diffuse to the resin surface due to concentration difference and electrostatic attraction, and exchange reactions will occur with the exchangeable cations on the resin. Therefore, using cation exchange resin can effectively isolate the cations in the moisture of the subgrade, thus avoiding the salt expansion phenomenon brought by salts to the subgrade and preventing the subgrade from expanding and deforming.

[0033] In some embodiments, a first composite waterproof geotextile is laid between the subgrade body and the cation exchange layer, a waterproof geomembrane is laid between the ordinary A / B group filler layer and the gravel layer, and a second composite waterproof geotextile is laid between the gravel layer and the concrete cover layer. The first composite waterproof geotextile, the waterproof geomembrane and the second composite waterproof geotextile are all composed of a plastic film as the anti-seepage base material and non-woven fabric; among them, the plastic film is polyethylene or polyvinyl chloride or HDPE film or LDPE film or EVA film; the non-woven fabric is polyester synthetic fiber or polypropylene synthetic fiber. Among them, the thickness of the first composite waterproof geotextile, the waterproof geomembrane and the second composite waterproof geotextile is preferably 0.004m or 0.005m or 0.006m. HDPE film is also known as high density polyethylene film, LDPE film (Low Density Polyethylene) is a low density polyethylene film blown after polymerizing ethylene through a polymerization process, and EVA film (Polyethylene vinyl acetate) is a film of ethylene-vinyl acetate copolymer.

[0034] The composite waterproof geotextile has the following advantages:

[0035] Improve waterproof effect and extend service life: By combining the advantages of different materials, the composite waterproof material can significantly improve the waterproof effect and extend the service life of the waterproof system. For example, some materials have good weather resistance but perform poorly in specific environments, while another material performs well in these environments. By using them in combination, a more comprehensive and reliable waterproof system can be created.

[0036] Adapt to extreme climate conditions: The composite waterproof material usually has excellent flexibility and tensile strength, and can maintain excellent waterproof performance under extreme climate conditions. For example, the waterproof material with a polymer substrate can still maintain excellent waterproof performance under extreme climate.

[0037] Environmental friendliness and breathability: The composite waterproof material incorporates nanotechnology and microporous technology, not only having good waterproof performance, but also possessing breathability and environmental friendliness. This avoids the problem of internal water vapor accumulation caused by long-term enclosure of traditional waterproof materials and reduces environmental pollution.

[0038] In some embodiments, the ordinary A / B group filler layer is A group high-quality railway subgrade filler and / or B group good railway subgrade filler. The A group high-quality railway subgrade filler includes various hard stones, such as hard block stones, as well as boulder soil, pebble soil, crushed stone soil, etc. with good gradation and fine-grained soil content less than 15%. These fillers are often used in key parts of railway subgrades due to their excellent physical properties and bearing capacity; the B group good railway subgrade filler includes soft block stones that are not easily weathered, as well as boulder soil, pebble soil, etc. with poor gradation but fine-grained soil content between 15% and 30%. These fillers are slightly inferior to the A group fillers in terms of physical properties and bearing capacity, but still can meet the bearing requirements of railway subgrades.

[0039] As Figure 3 shown, in some embodiments, the filling thickness of the crushed stone layer is preferably 0.3m or 0.4m or 0.5m, and the particle size range of the crushed stones in the crushed stone layer is 8cm - 10cm. The thickness of the concrete cover layer is preferably 3cm or 5cm or 8cm.

[0040] As Figure 4 and Figure 5 shown, according to on-site monitoring, the subgrade of high-speed railway in cold regions has a cumulative increasing trend during the long-term frost heave deformation process. Considering it as salt expansion effect, the deformation of the subgrade of high-speed railway in cold regions occurs under the combined action of frost heave and salt expansion. Based on the consideration of waterproof infiltration and overall stability, the existing subgrade structure adopts a ballastless track pavement structure, and its surface layer is integrally concreted and in a sealed state. In summer when the temperature is relatively high, the moisture in the lower layer of the subgrade evaporates and migrates upward. Due to the absence of exhaust holes, water vapor accumulates on the surface layer of the subgrade, causing the water content of the surface layer of the subgrade to increase, which is the so-called "lid effect". In the seasonally frozen soil area, the frost heave of the high-speed railway subgrade mainly occurs in the middle and upper layers (more than 1.5m) of the subgrade, and the frost heave amount in the crushed stone layer (more than 0.5m) can reach 30% of the total frost heave amount. This phenomenon indicates that the surface layer of the subgrade has a relatively high water content. And the high-speed railway adopts a ballastless track structure form with good integrity and sealing, and the possibility of external rainwater infiltration is relatively small. Therefore, the surface water mainly comes from the evaporation and migration of the moisture in the lower subgrade in summer, cools and converges on the surface layer of the subgrade, resulting in a relatively high frost heave amount in winter.

[0041] Meanwhile, according to the measured results, the subgrade has residual deformation during the freeze-thaw process and also shows an annual cumulative increasing trend. Therefore, for the construction of high-speed railways in seasonally frozen soil areas with high salt content, preventing salt heave and frost heave should be of equal importance. On the basis of the original "two-layer geotextile and one-layer geomembrane (a composite geomembrane used for anti-seepage, with a geotextile on the outer layer and a PVC plastic film for anti-seepage on the inner layer)" structure, a cation exchange resin layer and "breathing holes" in the upper cover plate of the subgrade are added. The frost heave of the subgrade with coarse-grained fillers in cold regions is mainly due to the upward migration and convergence of moisture below the subgrade in the cold season, mainly occurring in the upper and middle layers (more than 1.5 m) of the subgrade. The soluble salts (mostly sulfates, sulfites, and nitrites, etc.) in the subgrade and the formation migrate into the subgrade through moisture, and finally, as the moisture on the upper part of the subgrade evaporates, the soluble salts crystallize and precipitate, resulting in salt heave. According to the freeze-thaw and thaw-settlement laws of non-salt subgrades in Northeast China, the annual frost heave amount and thaw-settlement amount are basically in balance. However, after thaw-settlement of the subgrade of high-speed railways in cold regions, a part of it is still difficult to recover, showing residual deformation, and the annual cumulative increase in frost heave amount. Through the structural design of the cation exchange resin, the migration of SO3 -2 、SO4 -2 and other ions from the foundation soil and the coarse-grained fillers of the subgrade into the subgrade can be blocked. Moreover, the solubility of chloride salts is more than 10 times higher than that of sulfates and sulfites, thus greatly reducing the occurrence of salt heave diseases of high-speed railways in saline soil sections in the cold regions of the northwest. Therefore, by arranging "breathing holes" longitudinally along the subgrade, the summer steam water can be discharged from the subgrade through the breathing holes, reducing the water content in the upper layer of the subgrade, and thus weakening the frost heave deformation of the subgrade.

[0042] In some other embodiments, the present embodiment also provides a construction method for a high-speed railway anti-salt and water-blocking subgrade using coarse-grained fillers.

[0043] Construction preparation:

[0044] Subgrade body fillers: Coarse-grained fillers that meet the design requirements, such as crushed stones, sand and gravel, etc.

[0045] Cation exchange layer materials: Materials with good cation exchange performance, such as cation exchange resin layers.

[0046] Ordinary Group A / B fillers: It is required that the coefficient of uniformity (Cu) is between 55 - 60 and the coefficient of curvature (Cc) is between 0.2 - 0.8.

[0047] Composite waterproof geomembrane: The composite waterproof geomembrane has three layers, with geomembranes on the upper and lower layers and a waterproof membrane in the middle, and the total thickness is not less than 2 mm.

[0048] Block crushed stones: Stones that should be hard, durable, and not easily weathered, such as granite, limestone, etc. The particle size of the block crushed stones should meet the design requirements, generally 20 - 40 cm.

[0049] Concrete: Concrete with a strength grade meeting the design requirements.

[0050] It includes the following steps:

[0051] S1. Build the roadbed body by the replacement method; the specific construction method is as follows:

[0052] S101. Measure and set out the lines, and determine the roadbed side lines and elevation.

[0053] S102. Clear the site and remove the surface debris and soft soil layer.

[0054] S103. Build the roadbed body by the replacement method.

[0055] S2. Fill the cation exchange layer on the roadbed body and firm the cation exchange layer by the rolling and ramming method; the specific construction method is as follows:

[0056] S201. Lay the first composite waterproof geotextile on the top surface of the roadbed body to prevent the cation exchange layer material from mixing with the roadbed body filler.

[0057] S202. Lay the cation exchange layer material in multiple layers, with the thickness of each layer controlled within 20 cm, and the requirements for both sides of the roadbed boundary are 100 cm each.

[0058] S203. Use the static pressure of the roller to avoid damaging the structure of the cation exchange layer material.

[0059] S3. Lay the ordinary Group A / B filler layer on the cation exchange layer and firm the ordinary Group A / B filler layer by the rolling and ramming method; the specific construction method is as follows:

[0060] S301. Fill the roadbed body Group A / B filler in layers on the cation exchange layer, with the thickness of each layer controlled within 30 cm.

[0061] S302. Use the roller to compact in layers, with the water content controlled at 5% and the compaction degree controlled at 95%.

[0062] S4. Lay the gravel layer on the ordinary Group A / B filler layer and firm the gravel layer by the rolling and ramming method; the specific construction method is as follows:

[0063] S401. Lay the waterproof geomembrane on the ordinary Group A / B filler layer.

[0064] S402. Use manual or mechanical methods to lay the crushed stones on the waterproof geomembrane according to the design requirements.

[0065] S403. The crushed stones should be placed stably, with the large surface facing down and the small surface facing up.

[0066] S404. There should be a 2 - 3 cm gap between the crushed stones.

[0067] S405. Use a roller to compact the crushed stone layer.

[0068] S406. When compacting, it should be light first and then heavy, slow first and then fast.

[0069] S407. The number of compaction passes should be determined according to the thickness and compaction degree requirements of the block crushed stone layer.

[0070] S5. Pour the concrete cover layer on the crushed stone layer, and drill a plurality of breathing holes on the concrete cover layer. The specific construction method is as follows:

[0071] S501. Lay the first composite waterproof geotextile on the crushed stone layer;

[0072] S501. Install the formwork on the top surface of the first composite waterproof geotextile layer. The formwork should be firm and stable.

[0073] S502. Pour the concrete and vibrate it thoroughly with an insertion vibrator.

[0074] S503. After the concrete begins to set, carry out surface finishing and polishing.

[0075] S504. After the concrete finally sets, carry out maintenance in a timely manner.

[0076] S505. Drill holes on the concrete cover layer according to the design requirements. The hole diameter and spacing are determined according to the design requirements.

[0077] S506. Clean the sundries in the holes to ensure the smoothness of the breathing holes.

[0078] 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 concept and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A high-speed railway anti-salt and water-blocking subgrade using coarse-grained fillers, characterized in that, The invention comprises a roadbed body, a cation exchange layer, a common A / B group filler layer, a crushed stone layer and a concrete cover layer which are stacked in sequence. The concrete cover layer is provided with a plurality of breathing holes, and each of the breathing holes is connected to the crushed stone layer.

2. The high-speed railway anti-salt water-blocking subgrade using coarse-grained fillers according to claim 1, characterized in that The material of the cation exchange layer is cation exchange resin.

3. The high-speed railway anti-salt water-blocking subgrade using coarse-grained fillers according to claim 1, characterized in that, A first composite waterproof fabric is laid between the roadbed and the cation exchange layer, a waterproof geomembrane is laid between the common A / B group filler layer and the gravel layer, and a second composite waterproof fabric is laid between the gravel layer and the concrete cover layer.

4. The high-speed railway salt-proof and water-blocking subgrade using coarse-grained fillers according to claim 3, characterized in that, The first composite waterproof fabric, the waterproof geomembrane and the second composite waterproof fabric are all composited with a plastic film as an anti-seepage substrate and a non-woven fabric; wherein the plastic film is polyethylene or polyvinyl chloride or HDPE film or LDPE film or EVA film; and the non-woven fabric is polyester synthetic fiber or polypropylene synthetic fiber.

5. The high-speed railway anti-salt water-blocking subgrade using coarse-grained fillers according to claim 3, characterized in that, The thickness of the first composite waterproof fabric, the waterproof geomembrane and the second composite waterproof fabric are all in the range of 0.004m to 0.006m.

6. The high-speed railway anti-salt water-blocking subgrade using coarse-grained fillers according to claim 1, characterized in that The common A / B group filler layer is A group high-quality railway roadbed filler and / or B group good railway roadbed filler.

7. The high-speed railway salt-proof and water-blocking subgrade using coarse-grained fillers according to claim 1, characterized in that, The roadbed body is a rammed soil layer.

8. The high-speed railway anti-salt water-blocking subgrade using coarse-grained fillers according to claim 1, characterized in that, The filling thickness of the crushed stone layer ranges from 0.3m to 0.5m, and the crushed stone particle size of the crushed stone layer ranges from 8cm to 10cm.

9. The high-speed railway anti-salt water-blocking subgrade using coarse-grained fillers according to claim 1, characterized in that, The thickness of the concrete cover layer ranges from 3 cm to 8 cm.

10. A construction method of a high-speed railway anti-salt water-blocking subgrade using coarse-grained fillers as described in any one of claims 1 to 9, characterized in that, The steps include: S1. Use the replacement method to build the roadbed; S2, constructing a cation exchange layer on the roadbed, and firmly securing the cation exchange layer by rolling and compacting; S3, laying a common A / B group filler layer on the cation exchange layer, and firmly pressing the common A / B group filler layer by rolling and compacting; S4, laying a crushed stone layer on the ordinary A / B group filling layer, and firming the crushed stone layer by rolling and compacting; S5, pouring the concrete cover layer on the gravel layer, and drilling a plurality of breathing holes on the concrete cover layer.

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