Semi-rigid base asphalt pavement structure

Abstract

The utility model discloses a semi-rigid base asphalt pavement structure, which comprises an asphalt layer, a base layer and a cushion layer, a functional layer is arranged between the base layer and the asphalt layer, the functional layer comprises a plurality of geogrids laid on the base layer and geotechnical cloth arranged above the geogrids, the geogrids are in lap joint and are fixed through U-shaped metal sheets, and the cushion layer is arranged on the base layer. According to the utility model, not only can the soil particle loss be prevented, the drainage is convenient, the water can smoothly pass through, and the influence on the flatness and the service life of the road surface caused by shrinkage cracks generated by volume shrinkage of the base material due to water evaporation be avoided, but also the strength and the stability of the soil body can be enhanced, and the service life of the road surface is prolonged. And pavement diseases are avoided.

Description

Technical Field

[0001] This utility model relates to the field of road engineering technology, and in particular to a semi-rigid base asphalt pavement structure. Background Technology

[0002] Semi-rigid base courses hold an irreplaceable necessity and core importance in road construction. With the surge in traffic volume and the increasing proportion of heavy-duty vehicles, traditional flexible base courses struggle to withstand high-frequency loads. In contrast, semi-rigid base courses, with their high-strength slab structure formed by stable aggregates using inorganic binders such as cement and lime, effectively distribute vehicle loads. Their 7-day compressive strength reaches 3–5 MPa, and their compressive resilient modulus reaches 1500–3000 MPa, significantly reducing subgrade deformation and meeting the stringent load-bearing capacity requirements of high-grade highways. Furthermore, their materials can largely absorb industrial solid waste such as fly ash and steel slag, aligning with my country's development direction of green infrastructure and resource recycling. The construction technology is mature, and the cost is 20%–30% lower than that of flexible base courses, making them an economical choice for large-scale road construction.

[0003] In terms of importance, semi-rigid base courses, as a key load-bearing layer in pavement structure, combine the mechanical properties of rigid and semi-rigid materials. They can form a continuous slab to uniformly transfer loads and can also accommodate minor subsurface deformations to a certain extent, extending pavement service life (design life 15-20 years). In complex environments such as soft soil foundations and high groundwater levels, their excellent water stability and erosion resistance can effectively curb pumping, frost heave, and other defects, ensuring long-term road performance. Furthermore, under the "strong base, thin surface" design concept, semi-rigid base courses, through optimized thickness and material ratios, reduce surface layer costs while improving overall structural durability, meeting the goal of life-cycle cost control.

[0004] As the main base structure for over 70% of my country's high-grade highways, semi-rigid base courses continue to support transportation infrastructure construction due to their technical and economic advantages and optimizable performance. In the future, with the integration of low-carbon materials and intelligent construction technologies, they will further develop towards greening, crack resistance, and refinement, ensuring road service performance while contributing to the achievement of "dual-carbon" goals.

[0005] Chinese patent application number "2013202659461" discloses a semi-rigid pavement structure using a bonded graded crushed stone mixture. This semi-rigid pavement structure includes an asphalt layer and a semi-rigid base course, with a graded crushed stone layer laid between the asphalt layer and the semi-rigid base course. The aggregate of the graded crushed stone layer is bonded limestone graded crushed stone, and the binder is asphalt. This technical solution improves the stiffness of the graded crushed stone to a certain extent, thereby reducing road surface deflection while maintaining its original performance. However, it still has the following problems: its high modulus characteristics make it less resistant to deformation, and it is prone to fatigue cracking under repeated heavy loads. Repairing base course damage often requires full-thickness excavation and reconstruction, resulting in high maintenance costs. Furthermore, traditional semi-rigid materials have low porosity and insufficient drainage capacity, and long-term water accumulation may cause base course softening. Utility Model Content

[0006] The purpose of this invention is to provide a semi-rigid base asphalt pavement structure that not only prevents soil particle loss and facilitates drainage, allowing water to pass through smoothly, but also avoids shrinkage cracks caused by the volume shrinkage of the base material due to water evaporation, thus affecting the pavement smoothness and service life. Furthermore, it can enhance the soil strength and stability, preventing pavement defects, thereby solving the problems in the prior art.

[0007] To achieve the above objectives, this utility model employs the following technical solution:

[0008] A semi-rigid base asphalt pavement structure includes an asphalt layer, a base course beneath the asphalt layer, and a subbase beneath the base course. A functional layer is provided between the base course and the asphalt layer. The functional layer includes a plurality of geogrids laid on the base course and geotextiles placed on top of the geogrids. The geogrids overlap and are fixed by U-shaped metal strips. An anchoring device is provided between the geogrids and the base course to anchor the geogrids to the base course.

[0009] Furthermore, the anchoring device includes an anchor column vertically disposed in the base layer, a fastening end disposed on the upper part of the anchor column, and an anchoring end disposed on the lower part of the anchor column. The end of the anchoring end is a pointed structure, and several anchor claws are symmetrically distributed on the side wall of the anchoring end along the axial direction of the anchor column. Each anchor claw has a limiting baffle on one side perpendicular to the side wall of the anchor column to prevent the anchor column from moving in the vertical direction.

[0010] Furthermore, an adjustment device is provided between the anchor claw and the anchor post. The adjustment device includes a sleeve that is threadedly connected to the anchor post. An elastic element is abutted above the sleeve. The elastic element is sleeved on the anchor post. A retaining ring is provided on the anchor post corresponding to the upper end of the elastic element. The retaining ring abuts against the upper end of the elastic element.

[0011] Furthermore, the height of the geogrid does not exceed the height of the base material, and the geotextile is laid on the upper surface of the base.

[0012] The beneficial effects of this utility model are as follows: This utility model enhances the characteristics of the base structure by laying geotextile and geogrid between the asphalt layer and the base layer of the road structure. Among them, the water entering the base layer can be discharged laterally along the geotextile through the planar drainage performance of the geotextile, avoiding the shrinkage cracks caused by the volume shrinkage of the base material due to water evaporation, which would reflect onto the asphalt layer and affect the smoothness and service life of the road. Moreover, the geogrid enhances the strength and stability of the semi-rigid base layer, preventing fatigue cracking of the semi-rigid base layer under repeated heavy loads, thus avoiding road damage. Attached Figure Description

[0013] Figure 1 A partial cross-sectional view of a semi-rigid base asphalt pavement structure provided for this utility model;

[0014] Figure 2 for Figure 1 Enlarged structural diagram of section A;

[0015] Figure 3 An assembly structure diagram of the anchoring device and U-shaped metal sheet provided by this utility model;

[0016] Figure 4 The overall structural diagram of the anchor column provided by this utility model;

[0017] Figure 5 An assembly structure diagram of the anchor claw provided by this utility model.

[0018] The diagram shows the following labels: 100, asphalt layer; 200, base course; 300, subbase; 400, functional layer; 410, geogrid; 420, geotextile; 500, anchoring device; 510, anchor post; 511, retaining ring; 520, fastening end; 521, fastening groove; 530, anchoring end; 600, U-shaped metal sheet; 700, anchor claw; 710, limiting baffle; 800, sleeve; 900, elastic element. Detailed Implementation

[0019] To make the above-mentioned objectives, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.

[0020] In the description of this utility model, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "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, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0021] The following is an example:

[0022] A semi-rigid base course 200 asphalt pavement structure includes an asphalt layer 100, a base course 200 disposed below the asphalt layer 100, and a subbase 300 disposed below the base course 200. A functional layer 400 is provided between the base course 200 and the asphalt layer 100. The functional layer 400 includes several geogrids 410 laid on the base course 200 and geotextiles 420 disposed above the geogrids 410. The geogrids 410 overlap and are fixed by U-shaped metal sheets 600. An anchoring devices 500 are provided between the geogrids 410 and the base course 200 to anchor the geogrids 410 to the base course 200. Specifically, the height of the geogrids 410 does not exceed the height of the base course 200 material, and the geotextiles 420 are laid on the base course 200. On the upper surface, the U-shaped metal sheet 600 is fixedly connected to the end of the anchoring device 500 by bolt fasteners. Among them, the geotextile 420 is a needle-punched nonwoven geotextile 420, mainly made of polyester fiber as raw material, which is made by carding into a net and needle-punching reinforcement. The fibers are randomly distributed and the pore structure is irregular, which has good permeability, filtration and adsorption. The geogrid is made of glass fiber as reinforcement material and coated with alkali-resistant and wear-resistant resin coating. The grid structure of the glass fiber geogrid 410 is relatively regular, generally square or rectangular. Glass fiber has the characteristics of high strength and high modulus, which effectively improves the constraint ability of the soil. Its pore size is relatively small, which can better combine with the base layer 200 granular material, and can effectively prevent the generation and development of pavement cracks.

[0023] Semi-rigid base course 200 has the problem of shrinkage cracking, and the problem of drying shrinkage cracks is particularly prominent in asphalt pavement. Drying shrinkage cracks are caused by the volume shrinkage of base course 200 material due to water evaporation. These cracks will reflect upward to the asphalt surface layer, forming reflective cracks, which affect the smoothness and service life of the pavement. In addition, under repeated vehicle loads, semi-rigid base course 200 is prone to fatigue failure, which leads to a decrease in the strength of base course 200 and thus causes pavement distress.

[0024] In the subgrade structure of this technical solution, water entering the base course 200 can be discharged laterally along the geotextile 420 through the planar drainage performance of the geotextile 420. This avoids the shrinkage cracks caused by the volume shrinkage of the base course 200 material due to water evaporation, which would then be reflected onto the asphalt layer 100, affecting the pavement smoothness and service life. Furthermore, the geogrid enhances the strength and stability of the semi-rigid base course 200, preventing fatigue cracking of the semi-rigid base course 200 under repeated heavy loads, thus preventing pavement distress.

[0025] As a further technical solution in this embodiment, the anchoring device 500 includes an anchor column 510 vertically disposed in the base layer 200, a fastening end 520 disposed on the upper part of the anchor column 510, and an anchoring end 530 disposed on the lower part of the anchor column 510. The end of the anchoring end 530 is a pointed structure. Four anchor claws 700 are symmetrically distributed on the side wall of the anchoring end 530 along the axial direction of the anchor column 510. Each anchor claw 700 is provided with a limiting baffle 710 on one side perpendicular to the side wall of the anchor column 510 to prevent the anchor column 510 from moving in the vertical direction. In addition, a fastening groove 521 suitable for accommodating the U-shaped metal piece 600 is vertically opened on the end face of the fastening end 520. The U-shaped metal piece 600 is fixed to the anchor column 510 by bolts and fasteners passing through the fastening end 520 and the U-shaped metal piece 600 in sequence. Thus, the geogrid 410 is fixed to the base layer 200 by the anchoring device 500.

[0026] As a further technical solution in this embodiment, an adjustment device is provided between the anchor claw 700 and the anchor post 510. The adjustment device includes a sleeve 800 threadedly connected to the anchor post 510. An elastic element 900 is abutted above the sleeve 800. The elastic element 900 is sleeved on the anchor post 510. A retaining ring 511 is provided on the anchor post 510 corresponding to the upper end of the elastic element 900. The retaining ring 511 abuts against the upper end of the elastic element 900. The elastic element 900 is a compression spring. Each anchor claw 700 is welded to the sleeve 800, which can prevent the anchoring device 500 from moving laterally in the horizontal direction.

[0027] In construction environments with different specifications, the position and height of the 800mm spiral adjusting sleeve can be used to adapt to the filling height of the 200mm aggregate in the base layer.

[0028] When laying the functional layer 400, first lay the geogrid 410. Unfold the geogrid 410 on the leveled base layer 200 to make it flat and wrinkle-free. Lay it according to the design requirements in terms of direction and spacing. Connect the geogrid 410 by overlapping. Two geogrids 410 are clamped together by U-shaped metal strips 600. The overlap length between geogrids 410 is not less than 20cm. Fix the geogrid 410 to the base layer 200 by anchoring devices 500. The fixing interval is not more than 60cm to ensure the stability of the geogrid 410. Then lay the geotextile 420. Lay the geotextile 420 on the fixed geogrid 410. Again, ensure it is flat and avoid twisting. The splicing of the geotextile 420 is done by overlapping, and the overlap width is not less than 10cm.

[0029] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. It will be apparent to those skilled in the art that this utility model is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or basic characteristics of this utility model. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of this utility model is defined by the appended claims rather than the foregoing description. Therefore, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this utility model, and no reference numerals in the claims should be construed as limiting the scope of the claims.

[0030] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A semi-rigid base course asphalt pavement structure comprising an asphalt layer, a base layer disposed below the asphalt layer, and a mat layer disposed below the base layer, characterized in that: A functional layer is provided between the base layer and the asphalt layer. The functional layer includes several geogrids laid on the base layer and geotextiles placed on top of the geogrids. The geogrids overlap and are fixed by U-shaped metal sheets. An anchoring device is provided between the geogrids and the base layer to anchor the geogrids to the base layer.

2. A semi-rigid base course asphalt pavement structure according to claim 1, characterized in that: The anchoring device includes an anchor column vertically installed in the base layer, a fastening end installed on the upper part of the anchor column, and an anchoring end installed on the lower part of the anchor column. The end of the anchoring end has a pointed structure, and several anchor claws are symmetrically distributed on the side wall of the anchoring end along the axis of the anchor column. Each anchor claw has a limiting baffle on one side perpendicular to the side wall of the anchor column to prevent the anchor column from moving in the vertical direction.

3. A semi-rigid base course asphalt pavement structure according to claim 2, characterised in that: An adjustment device is provided between the anchor claw and the anchor post. The adjustment device includes a sleeve that is threadedly connected to the anchor post. An elastic element is abutted on the upper part of the sleeve. The elastic element is sleeved on the anchor post. A retaining ring is provided on the anchor post corresponding to the upper end of the elastic element. The retaining ring abuts against the upper end of the elastic element.

4. The semi-rigid base course asphalt pavement structure according to claim 1, characterized in that: The height of the geogrid does not exceed the height of the base material, and the geotextile is laid on the upper surface of the base.

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