Composite drainage anti-frost heaving heat preservation roadbed in seasonal frozen area
By installing moisture-absorbing geotextile and impermeable geotextile drainage and insulation components in the roadbed of the seasonally frozen area, combined with slope structure and blind drain, the problems of frost heave and frost heave of the roadbed in the frozen soil area are solved, achieving efficient drainage and insulation, and improving the stability and service life of the roadbed.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SOUTHWEST PETROLEUM UNIV
- Filing Date
- 2025-05-27
- Publication Date
- 2026-05-12
AI Technical Summary
Roadbeds in seasonally frozen soil regions are prone to frost heave and frost heave, resulting in a short service life. Existing technologies have room for improvement in terms of drainage efficiency, heat preservation durability, and structural stability.
The system employs a top-down arrangement of a road surface layer, upper drainage and insulation components, cement-stabilized crushed stone layer, filler layer, gravel layer, and bottom reverse filter drainage components. It utilizes moisture-absorbing geotextiles and impermeable geotextiles combined with slope structures and blind drains to achieve efficient drainage and insulation, preventing frost heave and frost heave.
It achieves efficient drainage and excellent thermal insulation, prevents frost heave and frost heave, improves the stability and service life of the roadbed structure, and reduces maintenance costs.
Smart Images
Figure CN224227582U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of roadbed engineering technology, and in particular to a roadbed insulation and antifreeze structure for use in seasonally frozen soil areas. Background Technology
[0002] Seasonally frozen soil regions are widespread in my country. Roadbeds in these areas are subject to constant freeze-thaw cycles, making them prone to frost heave, frost heave, and other damage, severely impacting road capacity and lifespan, and resulting in high maintenance costs. The core cause of roadbed frost heave lies in the presence of sufficient moisture in the roadbed soil and the freezing of this moisture due to sustained low temperatures.
[0003] Therefore, effectively draining moisture from the roadbed, preventing external water replenishment, and combining this with insulation measures are key to solving roadbed frost damage in seasonally frozen soil regions. While existing technologies address these issues, there is still room for improvement in drainage efficiency, insulation durability, and structural stability. Summary of the Invention
[0004] The present invention aims to provide a composite drainage, frost heave prevention and heat insulation roadbed for seasonally frozen areas, in order to solve the problem that existing roadbeds in seasonally frozen soil areas are prone to frost heave and frost heave, resulting in a short service life.
[0005] To achieve the above objectives, this utility model provides the following technical solution:
[0006] A composite drainage, frost-resistant, heat-insulating roadbed for seasonally frozen areas includes, from top to bottom, a road surface layer, an upper drainage and heat-insulating component, a cement-stabilized crushed stone layer, a filler layer, a gravel layer, and a bottom reverse filter drainage component.
[0007] The upper drainage and insulation component includes an insulation layer, on the upper surface of the insulation layer is covered with a first impermeable geotextile, and on the upper surface of the first impermeable geotextile is covered with a first moisture-absorbing geotextile; the moisture-absorbing geotextile can drain the water in saturated soil and unsaturated soil to both sides of the roadbed through capillary action, and continuously drain the roadbed water through the siphon effect generated by the difference in humidity inside and outside.
[0008] The bottom reverse filtration drainage assembly includes a reverse filter layer located below the gravel layer. The bottom of the reverse filter layer has a slope structure sloping to both sides. A second impermeable geotextile is laid on this slope structure, and a second moisture-absorbing geotextile is laid above the reverse filter layer and between it and the gravel layer. The second impermeable geotextile effectively prevents soil loss from the reverse filter layer, and the bottom drainage layer with a 3% slope effectively drains water from the reverse filter layer into the blind ditch, reducing the moisture content of the roadbed.
[0009] Preferably, the insulation layer is an XPS insulation board; the first and second moisture-absorbing geotextiles are both woven from polypropylene strips and capillary water-conducting fiber bundles and extend to the outer edge of the roadbed slope shoulder. Beneficial effects
[0010] Compared with the prior art, the present invention has the following beneficial effects:
[0011] 1. High-efficiency drainage and seepage prevention: By setting specific functional moisture-absorbing geotextiles and seepage-proof geotextiles in the upper drainage and insulation components and the bottom reverse filter drainage components, combined with the slope structure and blind drain, it can actively guide pavement seepage water, capillary water inside the subgrade and possible groundwater away from the main subgrade structure, significantly reducing the subgrade moisture content.
[0012] 2. Excellent thermal insulation: The insulation layer effectively reduces heat loss from the roadbed soil, slows down the development of freezing depth, and inhibits the conditions for frost heave from the source.
[0013] 3. Comprehensive measures to prevent frost heave and prevent frost heave: By combining insulation and drainage, frost heave caused by low winter temperatures is prevented, and frost heave caused by saturated water content during the spring thaw is avoided.
[0014] 4. Stable and durable structure: The filter layer ensures the long-term effectiveness of the drainage system and prevents blockage caused by the loss of fine particles; the selection of materials and parameter design of each structural layer helps to improve the overall bearing capacity and stability of the roadbed, extend the service life of the road, and reduce maintenance costs. Attached Figure Description
[0015] Figure 1 This is a schematic diagram of the overall structure of one embodiment of the present utility model;
[0016] Figure 2 This is a partially enlarged schematic diagram of the upper drainage and heat insulation component in an embodiment of this utility model;
[0017] Figure 3 This is a partially enlarged schematic diagram of the bottom reverse filter drainage component in an embodiment of this utility model;
[0018] Figure 4 This is a partially enlarged schematic diagram of the filter layer in an embodiment of this utility model.
[0019] Explanation of markings in the diagram:
[0020] 1-Road surface layer; 2-Insulation layer; 3-Cement-stabilized crushed stone layer; 4-Filling layer; 5-Gravel layer; 6-Drainage ditch; 7-Slope structure;
[0021] A1 - First absorbent geotextile; A2 - First impermeable geotextile; A3 - Covering layer;
[0022] B1 - Second absorbent geotextile; B2 - First permeable geotextile;
[0023] C - Filter layer; C1 - Fine particle layer; C2 - Medium particle layer; C3 - Coarse particle layer; C4 - First permeable geotextile; C5 - Blind drain. Detailed Implementation
[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0025] Reference Figures 1 to 4 This utility model provides a composite drainage, frost-resistant, and heat-insulating roadbed for seasonally frozen areas.
[0026] The roadbed structure consists of the following components from top to bottom: pavement layer (1), upper drainage and insulation components, cement-stabilized crushed stone layer (3), filler layer (4), gravel layer (5), and bottom reverse filter drainage components.
[0027] The pavement layer 1 can be made of conventional pavement materials such as asphalt concrete or cement concrete. Its surface is preferably set with a drainage slope of 2% on both sides to facilitate the rapid drainage of rainwater from the road surface.
[0028] The upper drainage and insulation component is located below the road surface layer (1) and above the cement-stabilized crushed stone layer (3). The component includes an insulation layer (2). The insulation layer (2) is preferably made of XPS (extruded polystyrene foam) insulation board, and its thickness can be selected according to local frost depth, climate conditions and other factors, and can be set to 10cm to 20cm. In this embodiment, it is 15cm.
[0029] The upper surface of the insulation layer (2) is covered with a first impermeable geotextile (A2) to prevent further seepage of pavement water and protect the insulation material. The upper surface of the first impermeable geotextile (A2) is covered with a first moisture-absorbing geotextile (A1), which is preferably made of polypropylene strips and capillary water-conducting fiber bundles and has good capillary water absorption and water conductivity. The first moisture-absorbing geotextile (A1) can actively guide the water that seeps in through pavement joints or micro-cracks and the small amount of capillary water that may exist in the upper part of the subgrade to the two sides of the subgrade through its capillary action and the siphon effect formed by the humidity difference between the inside and outside of the subgrade. The first moisture-absorbing geotextile (A1) extends to the outer edge of the subgrade slope shoulder on both sides of the subgrade, with an extension length of not less than 60cm. Above the first moisture-absorbing geotextile (A1) and below the pavement layer (1), a soil cover layer (A3) can be set to protect the geotextile and serve as the underlying layer of the pavement layer.
[0030] The cement-stabilized crushed stone layer (3) is located below the upper drainage and insulation components. As one of the structural bearing layers of the roadbed, its 7-day unconfined compressive strength is preferably above 5MPa.
[0031] The filler layer (4) is located below the cement-stabilized crushed stone layer (3). It can be crushed stone soil or well-graded gravel soil with a fine particle content (particles with a particle size less than 0.075 mm) of 15%-30%, and compacted in layers.
[0032] The gravel layer (5) is located below the filler layer (4), and its main function is to serve as a waterproof layer and a stress diffusion layer. The gravel layer (5) is preferably composed of gravel with a particle size of no more than 30 cm, and the content of fine particles should be strictly controlled, for example, below 15%, to prevent capillary water from rising. A second layer of permeable geotextile can be laid between the gravel layer (5) and the upper filler layer (4) to prevent fine particles from the filler layer from entering the pores of the gravel layer and to maintain the drainage of the gravel layer.
[0033] The bottom reverse filter drainage component is located below the gravel layer (5) and is the main drainage and reverse filter structure at the bottom of the roadbed. The core of this component is the reverse filter layer (C). Before laying the reverse filter layer (C), the bottom of the roadbed trench needs to be treated, leveled and compacted (compaction degree not less than 95%), and constructed into a bottom slope structure (7) sloping towards both sides of the roadbed, with a slope preferably of 2%-5% (e.g., 3%). A second impermeable geotextile is fully laid on the bottom slope structure (7) to form an impermeable bottom surface, preventing groundwater from seeping up and guiding the water collected by the reverse filter layer to both sides.
[0034] The filter layer (C) is laid on top of the second impermeable geotextile, and its structure, from top to bottom, consists of a fine-particle layer (C1), a medium-particle layer (C2), and a coarse-particle layer (C3). Preferably, the fine-particle layer (C1) can be made of medium or coarse sand, the medium-particle layer (C2) can be made of gravelly sand, and the coarse-particle layer (C3) can be made of crushed stone or pebbles. The outer periphery of the filter layer (C) (except for the top surface, because the top surface is in contact with the second moisture-absorbing geotextile B1) is wrapped by the first permeable geotextile C4 (or B2) to prevent the filter layer particles from being lost into the surrounding soil and to maintain the integrity of its structure. On the top surface of the filter layer (C), above the fine-particle layer (C1) and below the gravel layer (5), the second moisture-absorbing geotextile (B1) is laid. The material and function of this moisture-absorbing geotextile are similar to those of the first moisture-absorbing geotextile (A1), and it is used to guide the capillary water that may accumulate in the gravel layer and the upper part of the filter layer to both sides of the roadbed. The second absorbent geotextile (B1) also extends beyond both sides of the roadbed, with an extension length of not less than 60cm.
[0035] Blind drains (C5) are installed at the bottom of both sides of the roadbed structure, connecting to the bottom edge of the coarse-grained layer (C3) of the filter layer (C). The blind drains (C5) can be constructed by wrapping permeable pipes with geotextile and filling with gravel, and are used to collect and drain water from the filter layer.
[0036] Slope protection measures such as planting vegetation can be taken on both sides of the roadbed to prevent soil erosion. At a certain distance from the toe of the roadbed slope, a surface drainage ditch (6) is set up to collect and drain surface runoff and water drained from the roadbed.
[0037] Construction method overview:
[0038] S1: Roadbed excavation and trench treatment: Excavate the roadbed according to the design elevation, level and compact the bottom of the trench, construct a bottom slope structure (7) that conforms to the design slope (e.g., 3%), and lay a second impermeable geotextile on it. Excavate blind drains (C5) at predetermined positions on both sides of the trench.
[0039] S2: Construction of the bottom reverse filter drainage assembly: Lay the coarse-grained layer (C3), medium-grained layer (C2), and fine-grained layer (C1) of the reverse filter layer (C) sequentially on the second impermeable geotextile, compacting each layer to ensure it meets the reverse filtration requirements. Wrap the sides and bottom of the reverse filter layer (C) with the first permeable geotextile C4 / B2 (if the second impermeable geotextile has not been laid first). Lay the blind drain (C5). Lay the second absorbent geotextile (B1) on top of the reverse filter layer (C), extending it to the outside of the roadbed.
[0040] S3: Construction of the main structure layer of the subgrade: Gravel layer (5), second permeable geotextile (if provided), filler layer (4), and cement-stabilized crushed stone layer (3) are laid sequentially on the second absorbent geotextile (B1), and compacted in layers according to the specifications.
[0041] S4: Construction of the upper drainage and insulation components: After the cement-stabilized crushed stone layer (3) reaches the design strength, lay the XPS insulation board of the insulation layer (2) to ensure that the joints between the boards are tight. Lay the first impermeable geotextile (A2) and the first moisture-absorbing geotextile (A1) on the insulation board in sequence, so that the moisture-absorbing geotextile extends to the outside of the subgrade. Lay the topsoil layer (A3) and compact it.
[0042] S5: Road surface and ancillary works construction: Lay the road surface layer (1). Protect the roadbed slope and construct ground drainage ditches on both sides (6).
[0043] Those skilled in the art should understand that the embodiments of this utility model are not limited to the specific structures described above. Any technical solutions obtained through equivalent substitution or transformation fall within the protection scope of this utility model. For example, the type of insulation material, the specific model of the geotextile, and the precise thickness of each structural layer can all be adjusted according to actual engineering needs and material development.
Claims
1. A composite drainage, frost-resistant, and heat-insulating roadbed for seasonally frozen areas, characterized in that, It includes, from top to bottom, a road surface layer (1), an upper drainage and insulation component, a cement-stabilized crushed stone layer (3), a filler layer (4), a gravel layer (5), and a bottom reverse filter drainage component; The upper drainage and insulation component includes an insulation layer (2), and a first impermeable geotextile (A2) is laid on the upper surface of the insulation layer (2), and a first moisture-absorbing geotextile (A1) is laid on the upper surface of the first impermeable geotextile (A2). The bottom reverse filter drainage assembly includes a reverse filter layer (C), which is located below the gravel layer (5). The bottom of the reverse filter layer (C) forms a slope structure (7) that slopes to both sides. A second impermeable geotextile is laid on the slope structure (7). A second moisture-absorbing geotextile (B1) is laid above the reverse filter layer (C) and between it and the gravel layer (5).
2. The roadbed according to claim 1, characterized in that: The insulation layer (2) is an XPS insulation board.
3. The composite drainage, frost heave prevention, and heat insulation roadbed for seasonally frozen areas according to claim 1, characterized in that: Both the first and second moisture-absorbing geotextiles (A1) are woven from polypropylene strips and capillary water-conducting fiber bundles and extend to the outer edge of the roadbed slope shoulder.
4. The roadbed according to claim 1, characterized in that: The filter layer (C) comprises a fine particle layer (C1), a medium particle layer (C2), and a coarse particle layer (C3) laid from top to bottom.
5. The roadbed according to claim 4, characterized in that: The outer periphery of the filter layer (C) is covered with a first permeable geotextile (C4), and blind drains (C5) are connected to the bottom of both sides of the filter layer (C).
6. The roadbed according to claim 1, characterized in that: The slope of the slope structure (7) is 2%-5%.
7. The roadbed according to claim 1, characterized in that: The surface of the pavement layer (1) is formed as a drainage slope that slopes to both sides; drainage ditches (6) are provided on both sides of the roadbed structure.
8. The roadbed according to claim 1, characterized in that: A second permeable geotextile is laid between the gravel layer (5) and the filler layer (4).
9. The roadbed according to claim 1, characterized in that: The upper drainage and insulation component also includes a soil cover layer (A3) covering the first moisture-absorbing geotextile (A1), and the road surface layer (1) is laid on the soil cover layer (A3).