A rigid-flexible combined pavement base structure suitable for desert highways

Abstract

The utility model discloses a kind of rigid-flexible combination pavement base structure suitable for desert highway belongs to desert highway structure technical field, including replacement layer, base layer, pavement layer from bottom to top sequentially laid;Base layer includes bottom base layer, lower base layer, buffer layer and upper base layer from bottom to top sequentially laid;Bottom base layer, lower base layer are semi-rigid base layer, and upper base layer is high molecular polymer stabilized aeolian sand macadam upper base layer, which is flexible base layer;Buffer layer uses polypropylene fiber grid or permeable nonwoven fabric material.A layer of high molecular polymer stabilized aeolian sand macadam upper base layer is increased between semi-rigid base layer and pavement layer, and high molecular polymer stabilized aeolian sand macadam upper base layer is flexible base layer, with strength and toughness, to avoid that single semi-rigid base layer leads to pavement crack.

Description

Technical Field

[0001] This utility model belongs to the field of desert highway structure technology, specifically relating to a rigid-flexible road base structure suitable for desert highways. Background Technology

[0002] The statements in this section are merely background information related to this utility model and do not necessarily constitute prior art.

[0003] Traditional road construction methods using materials such as limestone, soil, and gravel are scarce in desert regions, requiring long-distance transportation and resulting in high construction costs. To address this issue, existing technology discloses a roadbed and pavement reinforcement structure suitable for desert areas. This structure includes, from bottom to top, a roadbed, a subbase, a cement-fly ash stabilized aeolian sand aggregate base course, a reinforcement layer, a lower sealing layer, and a pavement layer. This solution uses materials such as cement, aggregates, aeolian sand, and fly ash to prepare the subbase and cement-fly ash stabilized aeolian sand aggregate base course, replacing natural gravel with aeolian sand, which is energy-saving, environmentally friendly, and reduces road construction costs.

[0004] The base structure in the above scheme is a semi-rigid base. The semi-rigid base provides excellent performance for the road load-bearing structure through its own strength and stiffness. However, a single semi-rigid base will crack when subjected to cyclic high and low temperature differences under the complex and changeable climate conditions in desert areas, which will lead to road surface cracking and affect the normal use and maintenance of the road. Utility Model Content

[0005] In view of this, the purpose of this utility model is to provide a rigid-flexible road base structure suitable for desert highways, which can solve the technical problem that the single semi-rigid base road surface in the existing technology is prone to cracking.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This embodiment discloses a rigid-flexible pavement base structure suitable for desert highways, comprising a replacement layer, a base layer, and a pavement layer laid sequentially from bottom to top; The base layer consists of the subbase, lower base layer, buffer layer and upper base layer, which are laid sequentially from bottom to top; The subbase and lower base are semi-rigid bases, while the upper base is a polymer-stabilized aeolian sand and gravel upper base, which is a flexible base. The buffer layer is made of polypropylene fiber mesh or permeable nonwoven fabric.

[0007] Preferably, the replacement layer is a natural sand and gravel replacement layer, and a composite geomembrane is laid between the replacement layer and the subbase.

[0008] Preferably, the subbase is a cement-fly ash-stabilized aeolian sand subbase with a density range of 1.5000 to 2.0000 g / cm³.

[0009] Preferably, the lower base layer is a cement-stabilized aeolian sand and gravel lower base layer with a density range of 2.0000 to 2.3000 g / cm³.

[0010] Preferably, the density range of the upper layer is 2.1000 to 2.4000 g / cm³.

[0011] Preferably, the pavement layer includes a lower layer above the top surface of the upper base course and an upper layer above the top surface of the lower layer; the lower layer is a coarse-grained asphalt concrete lower layer and the upper layer is a medium-grained asphalt concrete upper layer.

[0012] Preferably, the thickness of the base layer is 18-30cm, the thickness of the lower base layer is 10-20cm, the thickness of the upper base layer is 15-36cm, and the thickness of the buffer layer is 1-5mm.

[0013] Preferably, in highways with light traffic levels, the thickness of the subbase is 18–20 cm; the thickness of the lower base is 10–15 cm; and the thickness of the upper base is 15–25 cm.

[0014] Preferably, in highways with moderate traffic levels, the thickness of the subbase is 18–25 cm; the thickness of the lower base course is 12–18 cm; and the thickness of the upper base course is 18–30 cm.

[0015] Preferably, in highways with heavy traffic, the thickness of the subbase is 20–30 cm; the thickness of the lower base course is 14–20 cm; and the thickness of the upper base course is 20–36 cm.

[0016] Compared with the prior art, the advantages and positive effects of this utility model are: This invention adds a polymer-stabilized aeolian sand and gravel upper base layer between the semi-rigid base layer and the pavement layer. The polymer-stabilized aeolian sand and gravel upper base layer is a flexible base layer with strength and toughness, avoiding the cracking of the pavement caused by using a single semi-rigid base layer. At the same time, it can also disperse stress, reduce the impact of the upper load on the base layer, improve the road life and reduce road defects. By laying a buffer layer between the lower base layer and the upper base layer, it can alleviate reflective cracking caused by the difference in stiffness between the layers. Attached Figure Description

[0017] The accompanying drawings, which form part of this specification, are used to provide a further understanding of this utility model. The illustrative embodiments of this utility model and their descriptions are used to explain this utility model and do not constitute an improper limitation of this utility model.

[0018] Figure 1 This is an overall cross-sectional view of a rigid-flexible base course pavement structure suitable for desert highways according to an embodiment of this utility model; Figure 2 This is a schematic diagram of the base layer of an embodiment of this utility model; In the picture: 1. Replacement layer; 2. Composite geomembrane; 3. Subbase; 4. Lower base; 5. Buffer layer; 6. Upper base; 7. Lower layer; 8. Upper layer. Detailed Implementation

[0019] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0020] The present invention will now be described in detail with reference to the accompanying drawings. This embodiment discloses a rigid-flexible road base structure suitable for desert highways, such as... Figure 1 , Figure 2 As shown, it includes a replacement layer 1, a base layer, and a pavement layer laid sequentially from bottom to top; wherein the base layer includes a subbase layer 3, a lower base layer 4, a buffer layer 5, and an upper base layer 6 laid sequentially from bottom to top.

[0021] In this embodiment, the subbase 3 and lower base 4 are both semi-rigid bases, and the upper base 6 is a polymer-stabilized aeolian sand and gravel upper base, which is a flexible base. The polymer-stabilized aeolian sand and gravel upper base has strength and toughness, avoiding road surface cracking caused by using a single semi-rigid base. It can also disperse stress, reduce the impact of the superload on the base, improve road life, and reduce road defects. Laying a flexible base on top of the semi-rigid base can overcome the disadvantage of single semi-rigid bases cracking under the complex and variable climate conditions of desert areas when subjected to cyclic high and low temperature differences, leading to road surface cracking.

[0022] In this embodiment, a buffer layer 5 is laid between the lower base layer 4 and the upper base layer 6. The function of the buffer layer 5 is to mitigate reflective cracking caused by the difference in stiffness between the layers. It is easy to understand that the lower base layer 4 is a semi-rigid base layer, and the upper base layer 6 is a flexible base layer. Although the flexible base layer can overcome the disadvantage of cracking due to cyclic high and low temperature differences, when the semi-rigid base layer cracks, it is still possible for the cracks to be reflected upwards to the flexible base layer, causing the flexible base layer to crack. Laying the buffer layer 5 can effectively mitigate this situation.

[0023] In this embodiment, the buffer layer 5 is made of polypropylene fiber mesh or permeable nonwoven fabric. During buffer layer construction, the surface of the underlying base layer 4 must be thoroughly cleaned to ensure it is free of loose particles, mud, dust, or oil. The width of the buffer layer 5 should not be less than the width of the underlying base layer 4. The material should be dry, wrinkle-free, and undamaged, and should be cut and adjusted according to the site dimensions before laying. The buffer layer should be laid according to the principles of "direction, tautness, and firmness." The polypropylene fiber mesh or permeable nonwoven fabric should be laid flat on the underlying base layer surface along the route using manual or mechanical traction, maintaining tension and strictly prohibiting folds, curling edges, or wrinkles. The transverse overlap width of the polypropylene fiber mesh or permeable nonwoven fabric should be no less than 15 cm, and the longitudinal overlap width no less than 20 cm. The overlaps should be fixed with U-shaped nails or adhesive dots to prevent displacement. After the buffer layer is laid, use a steel wheel static roller with a capacity of 8 tons or more to perform 1 to 2 passes of initial compaction to enhance the adhesion. Only after the requirements are met can the paving operation of the polymer-stabilized aeolian sand and gravel upper base course begin.

[0024] like Figure 1 As shown, a composite geomembrane 2 is laid between the replacement layer 1 and the subbase layer 3. The composite geomembrane 2 is a waterproof material made of geotextile and geomembrane, used for seepage prevention. In this embodiment, the composite geomembrane 2 uses two layers of geotextile and one layer of geomembrane. In this embodiment, the replacement layer 1 is a natural sand and gravel replacement layer, which is carried out in layers, and the sand and gravel are uniformly graded.

[0025] like Figure 1 , Figure 2 As shown, the subbase 3 is laid on top of the replacement layer 1. The subbase 3 is a cement-fly ash stabilized aeolian sand subbase, formed by mixing cement, fly ash, aeolian sand, and water. It is a semi-rigid base layer that supports the superstructure through its own rigidity and strength. In this embodiment, cement accounts for 3% to 5% of the composition of the subbase 3, the ratio of fly ash to cement is 1:3 to 1:5, and the remainder is aeolian sand. In this embodiment, the density range of the subbase 3 is 1.5000 to 2.0000 g / cm³.

[0026] like Figure 1 , Figure 2 As shown, the lower base layer 4 is laid on top of the subbase layer 3. The lower base layer 4 is a cement-stabilized aeolian sand and gravel lower base layer, formed by mixing cement, fly ash, aeolian sand, gravel (or pebbles), and water. It is also a semi-rigid base layer, supporting the upper structure through its own rigidity and strength. In this embodiment, the components of the lower base layer 4 are: cement (4%–6%), fly ash (12%–18%), gravel (22%–30%), and aeolian sand (46%–62%).

[0027] In this embodiment, the mix proportion of the lower layer 4 is determined through stepwise filling and response surface methodology (BBD) design optimization. Graded crushed stone is used, with the following particle size distribution: 30%–40% for 20–25 mm crushed stone, 15%–25% for 10–20 mm crushed stone, and 35%–50% for 0–10 mm crushed stone. In the lower layer 4, aeolian sand completely replaces the 0–10 mm crushed stone. The density of the lower layer 4 ranges from 2.0000 to 2.3000 g / cm³.

[0028] It should be noted that after the cement-fly ash stabilized aeolian sand base course and the cement-stabilized aeolian sand and gravel subbase course are laid, they need to be covered with polyethylene film for water curing. Only after the strength of the cement-fly ash stabilized aeolian sand and gravel subbase courses has been tested by core drilling and found to meet the design requirements can the next process be carried out.

[0029] In this embodiment, the upper base layer 6 is laid on the top surface of the buffer layer 5. The upper base layer 6 is a polymer-stabilized aeolian sand and gravel upper base layer, which is formed by mixing polymer, gravel, and aeolian sand. It is a flexible base layer. Compared with traditional semi-rigid base layers such as cement / lime stabilized gravel materials, it has strong and tough characteristics, can disperse stress, reduce the impact of load on the base layer, and improve the service life of the road.

[0030] As a new type of road base polymer, the high molecular polymer is uniformly dispersed on the surface of stable materials such as soil and rock with water as the conductive medium. After effective compaction and water evaporation, an organic adhesive film is formed on the surface of the solid particles of soil and rock inside the road structure layer, which firmly binds them into a whole and forms a flexible structural layer.

[0031] In this embodiment, by weight percentage, the upper base layer 6 comprises 60%–70% crushed stone and 30%–40% aeolian sand; based on the mass of the substrate, 0.4%–1% of a polymer is added. In the upper base layer 6, aeolian sand completely replaces the 0–5 mm crushed stone. The weight ratio of graded crushed stone to aeolian sand is as follows: 14%–24% for 20–25 mm crushed stone, 14%–24% for 10–20 mm crushed stone, 35%–40% for 5–10 mm crushed stone, and 30%–40% for 0–5 mm crushed stone. In the upper base layer 6, aeolian sand completely replaces the 0–5 mm crushed stone. The density range of the upper base layer 6 is 2.1000–2.4000 g / cm³.

[0032] In this embodiment, the particle size range of the aeolian sand is 0.075mm to 0.25mm; the polymer used is polyethyl methacrylate; the crushing value of the graded crushed stone is not greater than 35%, and the content of needle-like and flaky particles is not more than 20%.

[0033] In some embodiments, the upper base layer 6 also contains 1% to 2% basalt fiber, which acts as a "reinforcement" to enhance the tensile, shear and crack resistance of the upper base layer 6.

[0034] like Figure 1 As shown, a road surface layer is laid on the top surface of the upper base layer 6. The road surface layer includes a lower layer 7 located on the top surface of the upper base layer 6 and an upper layer 8 located on the top surface of the lower layer 7. The road surface layer has a 1.5% slope from the middle to both sides to avoid water accumulation on the road. In this embodiment, the lower layer 7 is a coarse-grained asphalt concrete lower layer, and the upper layer 8 is a medium-grained asphalt concrete upper layer.

[0035] In this embodiment, the thickness of the replacement layer 1 is 120cm, and the thickness of the entire base layer (subbase, lower base layer, upper base layer) ranges from 43 to 86cm. Among them, the thickness of the subbase layer 3 ranges from 18 to 30cm, the thickness of the lower base layer 4 ranges from 10 to 20cm, and the thickness of the upper base layer 6 ranges from 15 to 36cm. It should be noted that the thickness of the buffer layer 5 (not included in the base layer) ranges from 1 to 5mm.

[0036] It should be noted that the thickness range of the entire base course, and even the thickness range of the subbase, lower base course, and upper base course, are related to the traffic level of the highway, which is divided into three levels: light, moderate, and heavy.

[0037] In light traffic grade highways, the thickness of the subbase 3 ranges from 18 to 20 cm; the thickness of the lower base 4 ranges from 10 to 15 cm; and the thickness of the upper base 6 ranges from 15 to 25 cm.

[0038] In highways with moderate traffic levels, the thickness of the subbase 3 ranges from 18 to 25 cm; the thickness of the lower base 4 ranges from 12 to 18 cm; and the thickness of the upper base 6 ranges from 18 to 30 cm.

[0039] In highways with heavy traffic, the thickness of the subbase 3 ranges from 20 to 30 cm; the thickness of the lower base 4 ranges from 14 to 20 cm; and the thickness of the upper base 6 ranges from 20 to 36 cm.

[0040] In a specific heavy traffic highway, the thickness of the subbase 3 is 30cm, the thickness of the lower base 4 is 18cm, the thickness of the upper base 6 is 20cm, the thickness of the coarse-grained asphalt concrete lower layer 7 is 7cm, and the thickness of the medium-grained asphalt concrete upper layer 8 is 5cm.

[0041] Although the specific embodiments of the present utility model have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present utility model. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solution of the present utility model are still within the scope of protection of the present utility model.

Claims

1. A rigid-flexible road base structure suitable for desert highways, characterized in that, It includes the replacement layer, base course, and pavement layer laid sequentially from bottom to top; The base layer consists of the subbase, lower base layer, buffer layer and upper base layer, which are laid sequentially from bottom to top; The subbase and lower base are semi-rigid bases, while the upper base is a polymer-stabilized aeolian sand and gravel upper base, which is a flexible base. The buffer layer is made of polypropylene fiber mesh or permeable nonwoven fabric.

2. The rigid-flexible road base structure suitable for desert highways as described in claim 1, characterized in that, The replacement layer is a natural sand and gravel replacement layer, and a composite geomembrane is laid between the replacement layer and the subbase.

3. The rigid-flexible road base structure suitable for desert highways as described in claim 1, characterized in that, The subbase is a cement-fly ash stabilized aeolian sand subbase with a density ranging from 1.5000 to 2.0000 g / cm³.

4. A rigid-flexible road base structure suitable for desert highways as described in claim 1, characterized in that, The underlying base layer is a cement-stabilized aeolian sand and gravel underlying base layer with a density range of 2.0000-2.3000 g / cm³.

5. A rigid-flexible road base structure suitable for desert highways as described in claim 1, characterized in that, The density range of the upper base layer is 2.1000-2.4000 g / cm³.

6. A rigid-flexible road base structure suitable for desert highways as described in claim 1, characterized in that, The pavement layer includes a lower layer above the top surface of the upper base layer and an upper layer above the top surface of the lower layer; the lower layer is a coarse-grained asphalt concrete lower layer and the upper layer is a medium-grained asphalt concrete upper layer.

7. A rigid-flexible road base structure suitable for desert highways as described in claim 1, characterized in that, The thickness of the base layer ranges from 18 to 30 cm, the thickness of the lower base layer ranges from 10 to 20 cm, the thickness of the upper base layer ranges from 15 to 36 cm, and the thickness of the buffer layer ranges from 1 to 5 mm.

8. A rigid-flexible road base structure suitable for desert highways as described in claim 1, characterized in that, In light traffic grade highways, the thickness of the subbase is 18–20 cm; the thickness of the lower base course is 10–15 cm; and the thickness of the upper base course is 15–25 cm.

9. A rigid-flexible road base structure suitable for desert highways as described in claim 1, characterized in that, In highways with moderate traffic levels, the thickness of the subbase layer ranges from 18 to 25 cm; the thickness of the lower base layer ranges from 12 to 18 cm; and the thickness of the upper base layer ranges from 18 to 30 cm.

10. A rigid-flexible road base structure suitable for desert highways as described in claim 1, characterized in that, In highways with heavy traffic, the thickness of the subbase layer ranges from 20 to 30 cm; the thickness of the lower base layer ranges from 14 to 20 cm; and the thickness of the upper base layer ranges from 20 to 36 cm.

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