Low fill subgrade construction

Abstract

The utility model provides a kind of low fill subgrade structure, comprising: subgrade reinforcing layer, subgrade reinforcing layer is sequentially provided with surface layer directly bearing traffic load from top to bottom, the vertical force of driving load transferred by surface layer is supported by base layer and is used for water isolation, drainage, frost heaving prevention cushion, cushion is paved on the top of original soil subgrade using original pavement milling material, cushion and base layer, base layer and surface layer are respectively bonded connection.The utility model structure is simple and reasonable, and has high integrity, improves the mechanical properties of low fill subgrade, effectively solves the problems such as insufficient bearing capacity of subgrade in section where subgrade filling height is insufficient, improves the stability and durability of low fill subgrade structure as a whole;Cushion is paved using original pavement milling material, improves the water resistance of low fill subgrade, and improves the utilization rate of building materials, reduces building energy consumption, reduces the discharge of construction waste, and protects the environment.

Description

Technical Field

[0001] This utility model relates to the field of roadbed construction engineering technology, and more specifically, to a low-fill roadbed structure. Background Technology

[0002] Under specific geological conditions, when the embankment height cannot meet the conventional design requirements, such as in soft soil foundations or collapsible loess, if the embankment height is insufficient, the original soil may have insufficient bearing capacity due to insufficient compaction, loose soil, or excessive water content. The mechanical properties of the original soil may not meet the requirements for the strength and stability of the roadbed. In such cases, low-fill technology needs to be used for treatment.

[0003] Low-fill treatment is a specialized technical measure adopted in highway engineering for specific geological conditions. Low-fill refers to the roadbed fill height being less than the total thickness of the pavement and subgrade, or less than the total thickness of the subgrade (usually 0.8m or 1.2m). Some also define low-fill roadbed as a road embankment with a height of less than 1.6 meters.

[0004] However, existing low-fill roadbeds often suffer from insufficient fill height and significant defects in the original soil, and are also susceptible to the influence of groundwater or surface water. As a result, they typically have disadvantages such as substandard mechanical properties and prominent hydrological risks, which reduce the stability of the roadbed. Utility Model Content

[0005] Therefore, the purpose of this utility model is to design a low-fill roadbed structure, a roadbed structure with a special structure designed for low-fill roadbeds, to improve the mechanical properties of low-fill roadbeds, solve the problem of insufficient foundation bearing capacity in road sections with insufficient fill height, and improve the overall stability and durability of low-fill roadbed structures; the use of milled material from the original road surface to pave the subbase effectively improves the water-proofing performance of low-fill roadbeds, increases the utilization rate of building materials, and reduces building energy consumption.

[0006] This utility model provides a low-fill roadbed structure, comprising: a roadbed reinforcement layer, wherein the roadbed reinforcement layer is provided from top to bottom with a surface layer that directly bears traffic load, a base layer that bears the vertical force of the traffic load transmitted by the surface layer, and a cushion layer for water isolation, drainage, and frost heave prevention. The cushion layer is made of milled material from the original road surface and laid on top of the original soil base. The cushion layer is bonded to the base layer and the base layer is bonded to the surface layer.

[0007] The original road surface milling material is the asphalt-aggregate mixture scraped off from the original damaged asphalt sand pavement using a milling machine. It is used as a subbase material for backfilling the original road surface. Directly utilizing waste road surface material for backfilling reduces the extraction of new materials, optimizes construction waste disposal, saves costs, reduces construction waste emissions, reduces pollution, and protects the environment.

[0008] Interlayer bonding effectively prevents interlayer slippage, ensuring uniform load transfer from the surface layer to the base layer and then to the subbase, thus improving the overall structural integrity. Good adhesion reduces moisture penetration and interlayer delamination, improving durability and extending the road's service life.

[0009] This structure is not only easy to construct and inexpensive, but also achieves a win-win situation for both economic and environmental benefits through material recycling and optimized design.

[0010] Furthermore, a slope protection layer is provided on the side of the roadbed reinforcement layer. The slope protection layer consists of a skeleton slope protection layer and a finishing layer from the inside out. The finishing layer covers part of the surface area of ​​the skeleton slope protection layer. The skeleton slope protection layer is paved with precast concrete blocks, and the finishing layer is a cement concrete layer of equal thickness.

[0011] This structure combines the stability of a framework slope protection layer with the protective properties of a finishing layer. The precast concrete block-paved framework slope protection layer effectively disperses the pressure of water flow on the slope, has strong erosion resistance, a stable structure, and prevents soil erosion, making it particularly suitable for soil slopes or sections prone to erosion. The finishing layer covers part of the framework, sealing the slope surface and preventing surface peeling or crumbling due to weathering and rainwater erosion, thus improving durability. Meanwhile, cement concrete itself has the characteristics of high strength, good stability, and long service life. Both precast block paving and cement finishing are mature construction techniques, convenient and efficient to construct, and require relatively little maintenance. It effectively improves the overall stability and durability of the roadbed slope.

[0012] Preferably, the finishing layer can also use materials such as mortar, lime and slag, with a mix ratio including cement, lime and slag, or cement, sand and slag, or sand and lime.

[0013] Preferably, the slope ratio of the slope protection layer is 1:0.5-1:1.

[0014] Furthermore, the surface layer is provided with anchor rods, the top of which is covered by the cement concrete layer, and the bottom of which extends from the surface layer and is embedded in the interior of the skeleton slope protection layer.

[0015] The top of the anchor rod is covered by a layer of cement concrete, which can effectively disperse stress and prevent the anchor rod head from rusting; the bottom extends deep into the interior of the retaining wall layer, which provides strong anchoring force and ensures that the entire protective layer is not easy to slip or fall off. It is especially suitable for slope projects that need to withstand large soil pressure or water erosion.

[0016] In addition, the cement concrete plaster layer itself has the characteristics of erosion resistance and seepage prevention. When used in conjunction with anchor bolts, it can better protect the slope from weathering and erosion and extend its service life.

[0017] By firmly connecting the surface layer and the retaining wall layer with anchor bolts, an integral load-bearing structure is formed, which significantly improves the stability and durability of slope protection.

[0018] Furthermore, a vegetation layer is provided on the area of ​​the slope protection layer not covered by the finishing layer, and the vegetation layer adopts any one or a combination of two of the following: a flat turf structure and a potted plant arrangement structure.

[0019] Vegetation helps rainwater infiltrate into the ground, replenishing soil moisture, reducing surface runoff, mitigating erosion at its source, effectively preventing soil erosion, and achieving a perfect combination of engineering protection and ecological restoration.

[0020] Laying turf is simple and inexpensive, making it suitable for large-scale, rapid greening; potted plants, on the other hand, are easy to replace or adjust locally, offering flexible construction and strong adaptability, especially suitable for complex terrain or areas requiring landscaping. Combining the two is even more adaptable to different slope conditions.

[0021] The precast concrete block skeleton slope protection layer provides a solid foundation, the finishing layer enhances the overall integrity, and the vegetation layer further protects the slope from erosion, extending the service life of the protective structure.

[0022] Furthermore, a subbase layer is provided between the bottom of the base layer and the subbase layer, and the subbase layer is paved with asphalt mixture or cement concrete.

[0023] Specifically, the main functions of the subbase layer include: It bears the vehicle load transferred from the surface layer and distributes it to the underlying subgrade, reducing stress concentration on the subgrade and thus improving the overall load-bearing capacity.

[0024] The auxiliary base course distributes the load, reduces stress and deformation on the subgrade, prevents uneven settlement, and enhances the stability of the pavement structure.

[0025] Improve the hydrological and temperature conditions of the roadbed, such as through drainage or water-proofing functions, to reduce the risk of seasonal frost heave, frost heave and other diseases, and ensure that the road surface remains stable in the long term.

[0026] As a secondary load-bearing layer, the subbase can effectively disperse the load stress transmitted by the base course, reduce roadbed deformation, and enhance the overall structural stability of the roadbed.

[0027] The construction technology for subbases paved with asphalt mixtures or cement concrete is mature and can adapt to different geological conditions and climatic environments, providing a stable working surface for subsequent construction. The subbase can optimize the interlayer modulus ratio, and its resilient modulus is between that of the base course and the subbase, which can balance the stiffness of adjacent layers and avoid stress concentration.

[0028] When the base course is not thick enough or the roadbed conditions are poor, a lower strength but more economical material can be used to lay the subbase course, which can reduce engineering costs and extend the service life of the road surface.

[0029] Furthermore, a bonding layer is provided between the bottom of the surface layer and the base layer. The bonding layer is paved with asphalt macadam (AM) mixture with high porosity to form a skeleton interlocking structure.

[0030] The bonding layer is designed as a skeleton structure formed by high-porosity AM mixture, which effectively disperses wheel load stress transmitted from the surface layer, avoids stress concentration in the base layer, thereby reducing the peak compressive stress of the base layer, reducing fatigue damage, and extending the service life of the road. The skeleton interlocking structure has a large internal friction angle and relies on the interlocking force and internal friction resistance between coarse aggregates to resist deformation, thus exhibiting high high-temperature stability and effectively resisting rutting, shoving, and other defects. Through the high-porosity skeleton interlocking structure, uniform stress transmission and interlayer synergistic stress are achieved, enhancing the synergy between the surface layer and the base layer. Furthermore, through stress dispersion and crack isolation mechanisms, the reflective impact of base layer cracking on the surface layer is reduced, significantly improving the overall pavement performance and service life.

[0031] The elastic modulus of the bonding layer (usually 500-1000MPa) is between that of the base layer and the surface layer, which can achieve a reasonable match between the interlayer moduli, making the load transfer smoother, reducing interlayer shear stress, and preventing the generation of reflective cracks.

[0032] In addition, the high porosity facilitates interlayer drainage and prevents water damage; meanwhile, its thickness is generally controlled at 4-8 cm, which can meet functional requirements without excessively increasing costs.

[0033] Preferably, the coarse aggregate content of the asphalt macadam AM mixture is 60%-70%, and the asphalt content is about 2.5%-3.5%.

[0034] Furthermore, the low-fill roadbed structure also includes: retaining structures, which are arranged on both sides of the surface layer, and the retaining structures are any one or a combination of reinforced concrete retaining walls, pile-slab retaining walls, and masonry retaining walls.

[0035] Reinforced concrete retaining walls enhance tensile strength with steel bars, making them suitable for applications requiring high bending resistance. They effectively distribute earth pressure and prevent wall cracking.

[0036] Pile-slab retaining walls combine deep support from pile foundations with partial soil retention from the slab panels. They are particularly suitable for soft soil foundations or projects requiring deformation control, offering flexible construction and minimal impact on the surrounding environment.

[0037] Stone masonry retaining walls utilize local stone resources, are easy to construct, and are economical.

[0038] Combined applications include: Reinforced concrete + stone masonry retaining wall: It balances strength and economy and is suitable for medium-load road sections.

[0039] Pile-slab type + reinforced concrete: used in complex geological conditions, such as scenarios where soft soil and high loads coexist.

[0040] Furthermore, the retaining structure is provided with multiple drainage outlets arranged at equal intervals along the road running route.

[0041] Multiple drainage outlets arranged at equal intervals can efficiently and evenly remove water accumulated behind the wall, effectively reducing soil moisture content, enhancing the stability of the retaining wall, and preventing wall damage caused by increased water pressure. A systematic drainage network ensures comprehensive drainage coverage, avoiding localized water accumulation. The equal-interval arrangement results in a more balanced distribution of drainage load, preventing localized stress concentration caused by uneven drainage. Furthermore, by adjusting the outlet spacing appropriately (such as reducing the spacing in rainy areas), it can adapt to different rainfall intensities, ensuring effective drainage under various climatic conditions.

[0042] Furthermore, the cross-section of the roadbed reinforcement layer slopes downwards from the centerline of the road to both sides.

[0043] This inclined cross-sectional structure allows water to flow naturally along the reinforced layer to both sides of the road, eventually draining out of the roadbed through the drainage system. This effectively guides and removes moisture from within the roadbed, preventing its accumulation. Especially in rainy areas or areas with high groundwater levels, this prevents roadbed softening, deformation, or damage caused by water accumulation, enhancing the overall stability of the roadbed and maintaining its strength and durability.

[0044] Furthermore, the elevation of the subbase is flush with the ground line after clearing.

[0045] The subbase elevation is flush with the cleared ground line, eliminating the need for additional subbase thickness adjustments. Utilizing the smooth surface after clearing ensures close contact between the subbase and the foundation, preventing stress concentration due to elevation differences and improving overall load-bearing uniformity. The flush design facilitates natural drainage of surface water, preventing water seepage from affecting the subgrade strength. It also reduces earthwork volume, saves material and labor costs, and improves construction convenience, making it particularly suitable for soft soil treatment or embankment sections.

[0046] This invention achieves a balance between the stability, durability, and ecological benefits of a roadbed through the coordinated operation of a multi-layered structure. The precast concrete block-paved framework slope protection layer provides strong resistance to erosion and deformation, while the cement concrete finishing layer covering a portion of it further enhances the overall integrity and protective effect of the slope. This combination is particularly suitable for slope engineering projects that need to withstand significant earth pressure or water erosion. The vegetation layer (plain turf or potted plants) on the framework slope protection surface not covered by the finishing layer not only beautifies the environment but, more importantly, its root system effectively consolidates the soil, preventing soil erosion and achieving a combination of engineering protection and ecological restoration. The asphalt mixture or cement concrete subbase at the bottom of the base course, as a secondary load-bearing layer, effectively disperses load stress, reduces roadbed deformation, and its resilience modulus, between that of the base course and the subbase, balances the stiffness of adjacent layers, avoiding stress concentration. A bonding layer of high-porosity asphalt macadam (AM) mixture is used between the surface layer and the base layer, forming a skeletal interlocking structure. This effectively disperses the wheel load stress transmitted from the surface layer, preventing stress concentration in localized areas of the base layer. Simultaneously, its high porosity facilitates interlayer drainage, preventing water damage. Reinforced concrete retaining walls, pile-slab retaining walls, or masonry retaining walls on both sides of the surface layer can be flexibly selected or combined according to specific engineering needs. These retaining structures effectively resist lateral earth pressure, prevent roadbed slope slippage, and ensure roadbed stability. Through the rational combination and coordinated operation of each structural layer, comprehensive and reliable protection is provided for the low-fill roadbed.

[0047] Compared with the prior art, the beneficial effects of this utility model of low-fill roadbed structure are as follows: This utility model designs a special roadbed structure for low-fill roadbeds. The structure is simple and reasonable, with strong integrity, which improves the mechanical properties of low-fill roadbeds and effectively solves the problem of insufficient foundation bearing capacity in road sections with insufficient fill height. It also improves the overall stability and durability of the low-fill roadbed structure. The use of milled material from the original road surface to pave the subbase effectively improves the water-proofing performance of the low-fill roadbed, increases the utilization rate of building materials, reduces building energy consumption, reduces the emission of construction waste, and protects the environment. Attached Figure Description

[0048] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a schematic diagram of the overall elevation structure of the low-fill roadbed structure according to an embodiment of the present utility model; Figure 2 This is a cross-sectional structural diagram of the roadbed reinforcement layer according to an embodiment of the present invention.

[0049] The markings in the attached figure are as follows: 1. Subgrade reinforcement layer; 2. Slope protection layer; 3. Original soil base; 4. Subbase layer; 5. Subbase layer; 6. Base layer; 7. Connecting layer; 8. Surface layer; 9. Ground line after clearing; 10. Center line of the route. Detailed Implementation

[0050] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, embodiments and features of the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0051] In the description of this utility model, it should be noted that the terms "inner" and "outer", etc., indicate the orientation or positional relationship based on the orientation 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, be constructed or operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0052] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0053] The embodiments of this utility model will be described in detail below with reference to the accompanying drawings: This utility model embodiment provides a low-fill roadbed structure, such as Figure 1The structure includes: a roadbed reinforcement layer 1, which consists of, from top to bottom, a surface layer 8 that directly bears traffic loads, a base layer 6 that bears the vertical force of the traffic load transmitted by the surface layer 8, and a subbase layer 4 for waterproofing, drainage, and frost heave prevention. The subbase layer 4 is constructed by milling the original road surface material and laying it on top of the original soil base 3. The subbase layer 4 is bonded to the base layer 6, and the base layer 6 is bonded to the surface layer 8. This interlayer bonding effectively prevents interlayer slippage, ensuring uniform load transfer from the surface layer 8 to the base layer 6 and then to the subbase layer 4, thus improving the overall structural integrity. Good bonding performance reduces moisture penetration and interlayer delamination, improving durability and extending the road's service life. A subbase layer 55 (e.g., ...) is provided between the bottom of the base layer 6 and the subbase layer 4. Figure 2As shown, the subbase 55 is paved with asphalt mixture or cement concrete. The subbase 55 bears the vehicle load transmitted from the surface layer 8 and distributes it to the underlying subgrade, reducing concentrated stress on the subgrade and thus improving overall load-bearing capacity. The auxiliary base layer 6 shares the load, reducing stress and deformation on the subgrade, preventing uneven settlement, and enhancing the stability of the pavement structure. It improves the hydrological and temperature conditions of the subgrade, for example, through drainage or waterproofing functions, reducing the risk of seasonal frost heave, frost heave, and other diseases, ensuring the pavement remains stable in the long term. As a secondary load-bearing layer, the subbase 55 effectively disperses the load stress transmitted by the base layer 6, reducing subgrade deformation and enhancing the overall structural stability of the subgrade. The construction technology of the asphalt mixture or cement concrete paved subbase 55 is mature and can adapt to different geological conditions and climatic environments, providing a stable working surface for subsequent construction. The subbase 55 can optimize the interlayer modulus ratio; its resilient modulus is between that of the base layer 6 and the subbase layer 4, balancing the stiffness of adjacent layers and avoiding stress concentration. A bonding layer 7 is installed between the bottom of the surface layer 8 and the base layer 6. The bonding layer 7 is paved with high-porosity asphalt-aggregate (AM) mixture, forming a skeleton-interlocking structure. The coarse aggregate content of the AM mixture is approximately 70%, and the asphalt content is approximately 3.5%. The bonding layer 7, with its high-porosity AM mixture skeleton structure, effectively disperses the wheel load stress transmitted by the surface layer 8, preventing stress concentration in the base layer 6, thereby reducing the peak compressive stress of the base layer 6, reducing fatigue damage, and extending the service life of the road. The skeleton-interlocking structure has a large internal friction angle and relies on the interlocking force and internal friction resistance between the coarse aggregates to resist deformation, thus exhibiting high high-temperature stability and effectively resisting rutting, shoving, and other defects. Through the high-porosity skeleton-interlocking structure, uniform stress transmission and interlayer synergistic stress are achieved, enhancing the synergistic effect between the surface layer 8 and the base layer 6. Furthermore, through stress dispersion and crack isolation mechanisms, the reflective impact of cracking in the base layer 6 on the surface layer 8 is reduced, significantly improving the overall pavement performance and service life. The elastic modulus of the bonding layer 7 (typically 500-1000 MPa) is between that of the base layer 6 and the surface layer 8, achieving a reasonable match between the interlayer moduli. This results in smoother load transfer, reduced interlayer shear stress, and prevention of reflective cracking. Furthermore, the higher porosity facilitates interlayer drainage, preventing water damage. Simultaneously, its thickness is generally controlled at 4-8 cm, meeting functional requirements without excessively increasing costs. A slope protection layer 2 is provided on the side of the roadbed reinforcement layer 1. The slope protection layer 2 consists of a framework slope protection layer and a finishing layer 8, arranged sequentially from the inside out. The finishing layer 8 covers a portion of the framework slope protection layer. The framework slope protection layer is paved with precast concrete blocks, and the finishing layer 8 is a layer of cement concrete of uniform thickness. This structure combines the stability of the framework slope protection with the protective properties of the finishing layer 8. The precast concrete block-paved framework slope protection layer effectively disperses the pressure of water flow on the slope, has strong erosion resistance, a stable structure, and prevents soil erosion, making it particularly suitable for soil slopes or sections prone to erosion. The finishing layer 8 covers part of the framework, sealing the slope surface and preventing surface peeling or crumbling of the roadbed slope due to weathering and rainwater erosion, thus improving durability. Simultaneously, cement concrete itself has the characteristics of high strength, good stability, and long service life. Both precast block paving and cement finishing are mature construction techniques, convenient and efficient, with relatively low maintenance workload in the later stages. It effectively improves the overall stability and durability of roadbed slopes. The slope protection layer 2 has a slope ratio of 1:0.5. Anchor bolts are installed inside the finishing layer 8. The top of the anchor bolts is covered by a cement concrete layer, and the bottom of the anchor bolts extends from the finishing layer 8 and embeds into the interior of the retaining wall layer. The cement concrete covering of the top of the anchor bolts effectively disperses stress and prevents corrosion of the anchor bolt head; the bottom extending into the retaining wall layer provides strong anchoring force, ensuring that the entire protective layer is not prone to slippage or detachment, making it particularly suitable for slope projects that need to withstand large soil pressure or water erosion. The cement concrete finishing layer 8 itself has erosion-resistant and seepage-proof properties. Working in conjunction with the anchor bolts, it better protects the slope from weathering and erosion, extending its service life. The anchor bolts firmly connect the finishing layer 8 to the retaining wall layer, forming an integrated load-bearing structure, significantly improving the stability and durability of the slope protection. The areas of the slope protection layer not covered by the finishing layer 8 are covered with a vegetation layer, which can be any one or a combination of two of the following: a flat turf structure, a potted plant arrangement structure, or a combination of both. The vegetation layer helps rainwater infiltrate the ground, replenishing soil moisture, reducing surface runoff, mitigating erosion at its source, and effectively preventing soil erosion, achieving a perfect combination of engineering protection and ecological restoration. Flat turf is simple to construct, low in cost, and suitable for large-scale rapid greening; potted plant arrangements are easy to replace or adjust locally, flexible in construction, and highly adaptable, especially suitable for complex terrain or areas requiring landscaping. The combination of the two is more adaptable to different slope conditions. The precast concrete block framework slope protection layer provides a solid foundation, the finishing layer 8 enhances the overall integrity, and the vegetation layer further protects the slope from erosion, extending the service life of the protective structure.

[0054] The retaining structures are located on both sides of surface layer 8, and are constructed using reinforced concrete retaining walls. These reinforced concrete retaining walls, enhanced with steel bars to improve tensile strength, are suitable for applications requiring high bending resistance, effectively dispersing soil pressure and preventing wall cracking. Multiple drainage outlets are evenly spaced along the road's route. These evenly spaced outlets efficiently and uniformly drain water behind the wall, effectively reducing soil moisture content, enhancing the stability of the retaining wall, and preventing wall damage due to increased water pressure. A systematic drainage network ensures comprehensive drainage coverage, preventing localized water accumulation. The evenly spaced arrangement results in a more balanced distribution of drainage load, preventing localized stress concentration caused by uneven drainage. By adjusting the outlet spacing appropriately (e.g., reducing the spacing in rainy areas), the system can adapt to different rainfall intensities, ensuring effective drainage under various climatic conditions.

[0055] The elevation of subgrade 4 is flush with the ground line 9 after clearing. Since the elevation of subgrade 4 is flush with the ground line 9 after clearing, there is no need to adjust the thickness of subgrade 4. The smooth ground after clearing is utilized directly, ensuring close contact between subgrade 4 and the foundation, avoiding stress concentration caused by elevation differences, and improving the overall load-bearing uniformity. The flush design with the ground facilitates natural drainage of surface water, preventing water seepage from affecting the subgrade strength. It also reduces earthwork volume, saves material and labor costs, and improves construction convenience, making it particularly suitable for soft soil treatment or embankment sections.

[0056] The cross-section of the roadbed reinforcement layer 1 slopes downwards from the road centerline 10 on both sides. This sloping cross-section allows water to flow naturally along the reinforcement layer to both sides of the road, ultimately draining out of the roadbed area through the drainage system. This effectively guides and drains moisture from within the roadbed, preventing water accumulation. Especially in areas with heavy rainfall or high groundwater levels, this prevents roadbed softening, deformation, or damage caused by water accumulation, enhancing the overall stability of the roadbed and maintaining its strength and durability.

[0057] In practical applications, the construction process for paving the subgrade reinforcement layer in this embodiment includes the following steps: (a) Before laying the subbase 4, thoroughly clean the surface of the base layer 6 of loose soil, dust, oil, or particles. For mortar and concrete residue adhering to the base layer 6, remove it with a shovel, chisel, or wire brush, then sweep it clean with a broom.

[0058] Moisten the base layer 6 with water, ensuring that the surface is moist but without any visible water. Then apply a layer of neat cement slurry (with a water-cement ratio controlled between 0.4 and 0.5) to enhance the adhesion between the base layer 6 and the subbase 4.

[0059] Immediately after applying the neat cement slurry, lay the subbase layer (4 concrete or other materials). Use leveling markers (such as leveling blocks or a horizontal line) as a reference to ensure uniform thickness during laying.

[0060] Important Notes: Because neat cement slurry is a commonly used bonding medium, its water-cement ratio needs to be strictly controlled. Too thin or too dry a ratio will affect the bonding effect. Therefore, the subbase layer (4) should be laid as soon as possible after applying the neat cement slurry to prevent the slurry from drying out. It is generally required to complete the laying before the cement initially sets.

[0061] If the base layer 6 is made of a dry or highly absorbent material (such as lightweight aggregate), it needs to be moistened in advance to prevent the base layer 6 from absorbing moisture too quickly, which could lead to the failure of the bonding layer.

[0062] Before bonding, the strength and flatness of the substrate (6) must be checked. If the substrate (6) is sandy or lacks strength, it should be repaired or reinforced first.

[0063] In low-temperature environments (such as winter construction), antifreeze measures must be taken to prevent the bonding layer from freezing and affecting its strength.

[0064] (ii) The bonding between the base course 6 and the surface course 8 is mainly achieved by setting a bonding layer 7, which is composed of asphalt-aggregate mixture and firmly connects the base course 6 and the surface course 8. Depending on the size and weight of the surface course 8 and the conditions of the base course 6, the following bonding methods are used: 1. Cold-mixed material connection method: A layer of cold-mixed material is first sprayed onto the surface of the base layer 6, and then the surface layer 8 is laid on top. The two layers are tightly connected by their own weight and ground vibration. This connection method is low-cost and easy to construct.

[0065] 2. Hot-mix asphalt bonding method: Heated asphalt is used as an adhesive. A layer of hot-mix asphalt is poured on the base layer 6, and then the surface layer 8 is laid directly on top of it. This method provides a good and strong bond, effectively preventing interlayer delamination.

[0066] 3. Asphalt dust bonding method: Sprinkle a layer of fine sand on the surface of the base layer 6, and then use asphalt spraying to bond it together, before laying the surface layer 8. This method is low-cost and relatively simple to construct.

[0067] 4. Cut-layer connection method: Cut a certain groove into the surface of the base layer 6, and then lay the surface layer 8 in it. This method has a better connection effect, especially suitable for situations where the load-bearing capacity of the base layer 6 is insufficient.

[0068] The low-fill roadbed structure in this embodiment is simple and reasonable, with strong integrity, which improves the mechanical properties of the low-fill roadbed, solves the problem of insufficient foundation bearing capacity in road sections with insufficient fill height, and improves the overall stability and durability of the low-fill roadbed structure. The use of milled material from the original road surface to pave the subbase improves the water-proofing performance of the low-fill roadbed, increases the utilization rate of building materials, reduces building energy consumption, reduces the emission of construction waste, and protects the environment.

[0069] The technical solution of this utility model has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the protection scope of this utility model is obviously not limited to these specific embodiments. Without departing from the principle of this utility model, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of this utility model.

[0070] The above description is merely a preferred embodiment of this utility model and is not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A low-fill roadbed structure, characterized in that, include: The roadbed reinforcement layer consists of, from top to bottom, a surface layer that directly bears traffic load, a base layer that bears the vertical force of the traffic load transmitted by the surface layer, and a cushion layer for water isolation, drainage, and frost heave prevention. The cushion layer is made of milled material from the original road surface and laid on top of the original soil base. The cushion layer is bonded to the base layer, and the base layer is bonded to the surface layer.

2. The low-fill roadbed structure according to claim 1, characterized in that, The side of the roadbed reinforcement layer is provided with a slope protection layer. The slope protection layer is provided with a skeleton slope protection layer and a finishing layer from the inside to the outside. The finishing layer covers part of the surface area of ​​the skeleton slope protection layer. The skeleton slope protection layer is paved with precast concrete blocks, and the finishing layer is a cement concrete layer of equal thickness.

3. The low-fill roadbed structure according to claim 2, characterized in that, Anchor bolts are installed inside the plastering layer. The top of the anchor bolts is covered by the cement concrete layer, and the bottom of the anchor bolts extends from the plastering layer and is embedded inside the skeleton slope protection layer.

4. The low-fill roadbed structure according to claim 2, characterized in that, The area of ​​the slope protection layer not covered by the surface layer is provided with a vegetation layer, which adopts any one or a combination of two of the following: a flat turf structure and a potted plant arrangement structure.

5. The low-fill roadbed structure according to claim 1, characterized in that, A subbase is provided between the bottom of the base layer and the subbase layer, and the subbase is paved with asphalt mixture or cement concrete.

6. The low-fill roadbed structure according to claim 1, characterized in that, A connecting layer is provided between the bottom of the surface layer and the base layer. The connecting layer is paved with asphalt-aggregate mixture with high porosity to form a skeleton interlocking structure.

7. The low-fill roadbed structure according to claim 1, characterized in that, The low-fill roadbed structure also includes: retaining structures, which are located on both sides of the surface layer, and the retaining structures are any one or a combination of reinforced concrete retaining walls, pile-slab retaining walls, and masonry retaining walls.

8. The low-fill roadbed structure according to claim 7, characterized in that, The retaining structure has multiple drainage outlets arranged at equal intervals along the road's route.

9. The low-fill roadbed structure according to claim 1, characterized in that, The cross-section of the roadbed reinforcement layer slopes downwards from the centerline of the road to both sides.

10. The low-fill roadbed structure according to claim 1, characterized in that, The elevation of the subgrade is flush with the ground line after clearing.

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