Roadbed structure

Abstract

The utility model belongs to the technical field of roadbed structures, and particularly discloses a roadbed structure which comprises an asphalt concrete surface layer. The anti-melt sinking supporting layer is laid on the lower side of the asphalt concrete surface layer; the gravel cushion layer is laid on the lower side of the anti-collapse supporting layer; the sand gravel layer is laid on the lower side of the sand gravel cushion layer, and blind ditches are formed in the sand gravel layer; the salinized soil layer is laid on the lower side of the sand gravel layer and located on the upper side of the roadbed bearing layer; the anti-collapse supporting layer is formed by welding hooked steel bars and geogrids, provides vertical and inclined support for the pavement, and can support the pavement during salt swelling and collapse; the gravel cushion layer can provide bearing capacity and freezing resistance; the partition layer and the anti-collapse supporting layer are arranged, so that the safety of the roadbed structure is effectively ensured, and the service life of the road is prolonged; the roadbed has the advantages of being good in solution subsidence resistance and salinized soil erosion prevention effect, high in applicability to salinized soil under the extreme temperature difference condition and good in roadbed stability, and the problem that an existing roadbed cannot resist solution subsidence and prevent salinized soil erosion is solved.

Description

Technical Field

[0001] The utility model belongs to the technical field of subgrade structures, and particularly relates to a subgrade structure. Background Art

[0002] The highway department stipulates that for subgrades in saline soil areas, saline soil is land where the content of easily soluble salts is greater than 0.3% in the surface soil layer with a depth of 1 meter. In road engineering, saline soil can be classified into chloride saline soil, chlorite saline soil, sulfite saline soil, sulfate saline soil, and carbonate saline soil according to the salt content; it can also be classified into slightly saline soil, moderately saline soil, strongly saline soil, and overly saline soil, etc. Subgrades in saline soil areas are classified as special foundations in geotechnical engineering.

[0003] In the foundation environment, when a saline soil subgrade is under extreme temperature difference conditions, the mechanical properties of the saline soil are more easily affected by the salts in the groundwater. Therefore, compared with general saline soil, the saline soil subgrade has stronger collapsibility, salt expansion, and corrosiveness; the existing construction of saline soil subgrades generally sets a sand cushion layer and a settlement prevention support layer at the base layer. Such a construction method has a good improvement effect on general saline soil subgrades, but for saline soil subgrades under extreme temperature difference conditions, it often cannot effectively inhibit the erosion of salt ions in water, thus affecting the safety of the subgrade structure and reducing the service life of the road; for example, in the utility model with the patent publication number: CN217758146U, a frost-resistant saline soil subgrade structure is disclosed. This subgrade structure sequentially lays a modified layer, a sand cushion layer, a settlement prevention support layer, and an asphalt concrete surface layer on the original saline soil subgrade, so as to support the road surface during salt expansion and settlement and increase the service life of the road surface; however, when this frost-resistant saline soil subgrade structure is in use, there are the following problems: 1. The saline soil subgrade structure is not very applicable to saline soil subgrades under extreme temperature difference conditions, which will lead to poor support during the frost heave and settlement process and affect the stability of the subgrade; 2. The water stability of the saline soil subgrade is poor, and it cannot effectively reduce the occurrence of subgrade diseases in the saline soft soil environment; 3. The materials selected for the saline soil subgrade structure are of high grade, resulting in high construction and maintenance costs of the road surface, etc.

[0004] Based on this, the utility model proposes a new type of subgrade structure to solve the problems existing in the above-mentioned prior art. Summary of the Invention

[0005] Aiming at the defects existing in the above-mentioned prior art, the purpose of the present utility model is to provide a subgrade structure. Through the arrangement of a saline soil layer, a gravel layer, a sand cushion layer, an anti-subsidence support layer and an asphalt concrete surface layer, this subgrade structure can effectively drain the groundwater under the subgrade along the blind ditch into the side ditch outside the subgrade; the arrangement of the cemented gravel mixture layer and the geotextile membrane layer as a separating layer completely and effectively prevents capillary water from carrying salt ions to erode the subgrade structure, which is beneficial to improving the water stability of the road subgrade structure. At the same time, it effectively reduces the occurrence of subgrade diseases in the saline soft soil environment; the arrangement of the sand cushion layer can prevent the harm caused by the frost heave and salt expansion of the saline soil; the anti-subsidence support layer composed of a geogrid layer can support the road surface when the saline soil undergoes salt expansion and subsidence, improving the service life of the road surface, and having a good effect on reducing the maintenance cost and maintenance cost of the road surface. It has the characteristics of good anti-subsidence and anti-saline soil erosion effects, strong applicability to saline soil under extreme temperature difference conditions, and good subgrade stability.

[0006] In order to achieve the above purpose, the technical solutions adopted by the present utility model are as follows:

[0007] A subgrade structure, in a trapezoidal structure, the subgrade structure includes an asphalt concrete surface layer; an anti-subsidence support layer, laid on the lower side of the asphalt concrete surface layer; a sand cushion layer, laid on the lower side of the anti-subsidence support layer; a gravel layer, laid on the lower side of the sand cushion layer, and a blind ditch is also provided in the gravel layer; a saline soil layer, laid on the lower side of the gravel layer and on the upper side of the subgrade bearing layer;

[0008] Based on the above technical features: This subgrade structure adopts a method of combining drainage, separation and support to drain the groundwater under the subgrade along the blind ditch into the side ditch outside the subgrade; the anti-subsidence support layer is provided with a cemented gravel mixture layer and a geotextile membrane layer as a separating layer, which effectively prevents capillary water from carrying salt ions to erode the subgrade structure, is beneficial to improving the water stability of the road subgrade structure, and at the same time effectively reduces the occurrence of subgrade diseases in the saline soft soil environment; a sand cushion layer is provided in the subgrade to prevent the harm caused by the frost heave and salt expansion of the saline soil; the anti-subsidence support layer composed of a geogrid layer in the subgrade can support the road surface when the saline soil undergoes salt expansion and subsidence, improving the service life of the road surface.

[0009] As a preferred scheme of the subgrade structure described in the present utility model, the asphalt concrete surface layer includes a fine-grained dense-graded asphalt concrete layer, laid at the bottom of the asphalt concrete surface layer; a medium-grained dense-graded asphalt concrete layer, laid above the fine-grained dense-graded asphalt concrete layer; a coarse-grained dense-graded asphalt concrete layer, laid above the medium-grained dense-graded asphalt concrete layer;

[0010] Based on the above technical features: The paving is carried out in a bottom-up paving method, and each layer is compacted after paving to form a complete road surface structure, so as to ensure the friction coefficient of the road surface through the setting of the coarse-grained dense-graded asphalt concrete layer.

[0011] As a preferred solution of a subgrade structure described in the present invention, the particle size of the fine-grained dense-graded asphalt concrete layer < the particle size of the medium-grained dense-graded asphalt concrete layer < the particle size of the coarse-grained dense-graded asphalt concrete layer;

[0012] Based on the above technical features: Through the setting method of the fine-grained dense-graded asphalt concrete layer, medium-grained dense-graded asphalt concrete layer and coarse-grained dense-graded asphalt concrete layer from bottom to top, it not only ensures the water absorption and permeability of the subgrade surface layer, avoids cracking of the subgrade and road surface at high temperatures, but also ensures the water resistance of the subgrade surface layer and avoids water seepage from damaging the subgrade.

[0013] As a preferred solution of a subgrade structure described in the present invention, the anti-settlement support layer includes a cementitious gravel mixture layer laid at the bottom of the anti-settlement support layer; a geomembrane layer laid above the cementitious gravel mixture layer; a geotextile layer laid above the geomembrane layer; a geogrid layer laid above the geotextile layer;

[0014] Based on the above technical features: Taking the cementitious gravel mixture layer as the base layer can effectively ensure the strength of the anti-settlement support layer. The geomembrane layer can effectively prevent back-seepage. The geotextile layer as an isolation layer can prevent salts and moisture from invading the upper subgrade. The geogrid layer can ensure the lateral and longitudinal subgrade support and prevent the overall sliding and collapse of the road surface.

[0015] As a preferred solution of a subgrade structure described in the present invention, the geogrid layer includes a number of geogrids, and hook-shaped steel bars are arranged obliquely downward at the connection nodes of the geogrids;

[0016] Based on the above technical features: The geogrids can ensure the lateral and longitudinal subgrade support, and the semicircular hook-shaped steel bars arranged obliquely downward can prevent the overall sliding and collapse of the road surface.

[0017] As a preferred solution of a subgrade structure described in the present invention, a wrapping layer is also provided on the inclined surfaces on both sides of the subgrade structure; the wrapping layer is covered on the inclined surfaces on both sides of the subgrade structure with 1:1.5% lime-improved soil according to a slope;

[0018] Based on the above technical features: The subgrade wrapping layer can not only play a slope protection role, but also prevent surface water or moist water vapor in the atmosphere from invading the subgrade structure layer, thereby ensuring the water stability of the subgrade structure layer.

[0019] As a preferred solution of a subgrade structure according to the present utility model, a drainage side ditch is further provided at the toe of the slope of the subgrade structure, and the drainage side ditch is adapted to the blind ditch;

[0020] Based on the above technical features: the drainage side ditch is used for drainage, and the retaining strip is used for retaining water to prevent water from flowing randomly.

[0021] The beneficial effects of the present utility model are as follows: The present utility model discloses a subgrade structure. Compared with the prior art, the improvements of the present utility model are as follows:

[0022] 1. The subgrade structure adopts a method combining derivation, separation, and support to drain the groundwater under the subgrade along the blind ditch into the side ditch outside the subgrade;

[0023] 2. A cementitious gravel mixture layer and a geotextile membrane layer isolation layer are provided in the subgrade, which effectively prevent capillary water from carrying salt ions to erode the subgrade structure, is beneficial to improving the water stability of the road subgrade structure, and at the same time effectively reduces the occurrence of subgrade diseases in the saline soft soil environment;

[0024] 3. A sand and gravel cushion layer is provided in the subgrade to prevent the hazards caused by frost heave and salt expansion of saline soil;

[0025] 4. The anti-subsidence support layer composed of a geogrid layer in the subgrade can support the road surface when the saline soil undergoes salt expansion and subsidence, improve the service life of the road surface, and has good effects in reducing the maintenance cost and maintenance cost of the road surface. It has the advantages of good anti-subsidence and anti-saline soil erosion effects, strong applicability to saline soil under extreme temperature difference conditions, and good subgrade stability. Description of the Drawings

[0026] Figure 1 It is a cross-sectional view of the subgrade structure of the present utility model;

[0027] Figure 2 It is a structural schematic diagram of the gravel layer of the present utility model;

[0028] Figure 3 It is a structural schematic diagram of the anti-subsidence support layer of the present utility model;

[0029] Figure 4 It is a structural schematic diagram of the asphalt concrete surface layer of the present utility model.

[0030] Wherein: 1. Asphalt concrete surface layer; 11. Fine-grained dense-graded asphalt concrete layer; 12. Medium-grained dense-graded asphalt concrete layer; 13. Coarse-grained dense-graded asphalt concrete layer; 2. Anti-subsidence support layer; 21. Cementitious gravel mixture layer; 22. Geomembrane layer; 23. Geotextile layer; 24. Geogrid layer; 241. Geogrid; 242. Hooked steel bar; 3. Sand and gravel cushion layer; 31. Gravel filter layer; 32. Artificially graded sand and gravel cushion layer; 4. Gravel layer; 5. Blind drain; 6. Saline soil layer; 7. Subgrade bearing layer; 8. Edge wrapping layer; 9. Drainage side ditch; 10. Retaining strip. Detailed implementation manners

[0031] In order to enable ordinary technicians in the field to better understand the technical solution of the present utility model, the technical solution of the present utility model will be further described below in conjunction with the accompanying drawings and embodiments.

[0032] Embodiment 1: Refer to the attached Figures 1-4 As shown, the present utility model provides a technical solution:

[0033] A subgrade structure, the subgrade structure is a trapezoidal structure, including

[0034] An asphalt concrete surface layer 1, the asphalt concrete surface layer 1 is used to form a complete road surface structure, and the laying thickness is 50 - 70 cm;

[0035] An anti-subsidence support layer 2, the anti-subsidence support layer is laid on the lower side of the asphalt concrete surface layer 1 and is used to resist the salt expansion and subsidence of the subgrade;

[0036] A sand and gravel cushion layer 3, the sand and gravel cushion layer 3 is laid on the lower side of the anti-subsidence support layer 2, and is laid by adopting the construction plan of "laying sand and stone in layers and compacting in thin layers", and mainly plays a supporting role;

[0037] A gravel layer 4, the gravel layer 4 is laid on the lower side of the sand and gravel cushion layer 3, and a blind drain 5 is also provided in the gravel layer 4 for discharging groundwater;

[0038] A saline soil layer 6, the saline soil layer 6 is arranged on the lower side of the gravel layer 4 and the upper side of the subgrade bearing layer 7, and is used to prevent the occurrence of subgrade diseases in the saline soft soil environment;

[0039] Specifically, during use, this roadbed structure adopts a method that combines export, separation, and support to drain the groundwater under the roadbed along the blind ditch into the side ditch outside the roadbed. The anti-settlement support layer is provided with a cementitious gravel mixture layer and a geotextile layer as a separation layer, which effectively prevents capillary water from carrying salt ions to erode the roadbed structure, is beneficial to improving the water stability of the roadbed structure of the road, and at the same time effectively reduces the occurrence of roadbed diseases in the saline soft soil environment. The roadbed is provided with a sand cushion layer that can prevent the damage caused by the frost heave and salt expansion of saline soil. The anti-settlement support layer composed of a geogrid layer in the saline soil layer of the roadbed can support the road surface when the saline soil undergoes salt expansion and settlement, and improve the service life of the road surface.

[0040] As a preferred implementation, as Figure 1 shown, edge layers 8 are also provided on the inclined surfaces on both sides of the roadbed structure. The edge layer 8 is covered on the roadbed slope with 8% lime-improved soil at a slope of 1:1.5, and the covering thickness of the edge layer 8 is 15 - 25 cm;

[0041] Specifically, during use, the roadbed edge layer 8 can not only play a role in slope protection, but also prevent surface water or moist water vapor in the atmosphere from invading the roadbed structure layer, thereby ensuring the water stability of the roadbed structure layer.

[0042] As a preferred implementation, as Figure 1 shown, the blind ditch 5 is arranged along the road direction, and a drainage layer and an anti-filter layer are provided in the blind ditch 5. The blind ditch 5 is filled with a permeable material, and seepage grooves are arranged horizontally along the cross-section of the roadbed. The anti-filter layer is arranged on the lower side of the blind ditch, and the drainage layer is on the upper layer of the blind ditch. The filling material of the anti-filter layer is anti-filter geotextile, and the filling material of the drainage layer is coarse-grained materials such as crushed stones and gravels;

[0043] Specifically, during use, the groundwater is drained out of the roadbed structure through a combination of flow and seepage.

[0044] As a preferred implementation, as Figure 1 shown, for use in conjunction with the blind ditch 5, a drainage side ditch 9 is also provided at a distance of 2 m outside the roadbed toe, which is used in conjunction with the blind ditch 5 to divert surface precipitation and underground drainage outside the roadbed range to ensure that the roadbed is in a dry or medium-wet state. And to ensure the drainage efficiency, the slope of the drainage side ditch 9 is designed to be 1:1.5, and a soil heap retaining strip 10 is provided on the side different from the roadbed structure;

[0045] Specifically, during use, the drainage side ditch 9 is used for drainage, and the retaining strip 10 is used to block water to prevent water from flowing randomly.

[0046] Example 2: As Figure 1 and Figure 2As shown, the paving thickness of the asphalt concrete surface layer 1 is 50 - 70 cm, including

[0047] a fine-grained dense-graded asphalt concrete layer 11, which is laid at the bottom of the asphalt concrete surface layer 1, and the aggregate particle size is 11 - 13 mm;

[0048] a medium-grained dense-graded asphalt concrete layer 12, which is laid above the fine-grained dense-graded asphalt concrete layer 11, and the aggregate particle size is 18 - 24 mm;

[0049] a coarse-grained dense-graded asphalt concrete layer 13, which is laid above the medium-grained dense-graded asphalt concrete layer 12, and the aggregate particle size is 27 - 32 mm;

[0050] Specifically, during paving, it is paved in a bottom-up manner, and each layer is paved and compacted layer by layer to form a complete road surface structure. By setting the coarse-grained dense-graded asphalt concrete layer 13, the friction coefficient of the road surface is ensured; through the setting method of the fine-grained dense-graded asphalt concrete layer 11, medium-grained dense-graded asphalt concrete layer 12, and coarse-grained dense-graded asphalt concrete layer 13 from bottom to top, both the water absorption and permeability of the subgrade surface layer are ensured, avoiding cracking of the subgrade and road surface at high temperatures, and the water resistance of the subgrade surface layer is also ensured, avoiding water seepage from damaging the subgrade.

[0051] Example 3: As Figure 1 and Figure 3 shown, the anti-settlement support layer 2 is used to resist salt expansion and settlement, including

[0052] a cementitious gravel mixture layer 21, which is formed by mixing gravel, cementitious material and water, and is laid at the bottom of the anti-settlement support layer 2, and the thickness of the cementitious gravel mixture layer 21 is 10 - 15 cm. During construction, a vibrating roller is required for compaction;

[0053] a geomembrane layer 22, which is laid above the cementitious gravel mixture layer 21;

[0054] a geotextile layer 23, which is laid above the geomembrane layer 22 and serves as an isolation layer to prevent salts and moisture from invading the upper subgrade;

[0055] a geogrid layer 24, which is laid above the geotextile layer 23 to ensure the lateral and longitudinal subgrade support and prevent the overall sliding and collapse of the road surface;

[0056] Specifically, during use, with the gelled gravel mixture layer 21 as the base layer, the strength of the anti-settlement support layer 2 can be effectively ensured. Through the geomembrane layer 22, anti-seepage can be effectively prevented. Through the geotextile layer 23 as an isolation layer, salt and moisture can be prevented from invading the upper roadbed. Through the geogrid layer 24, the roadbed support in the horizontal and vertical directions can be ensured, preventing the overall slippage and collapse of the road surface.

[0057] As a preferred embodiment, as Figure 3 shown, the geogrid layer 24 includes a number of geogrids 241, and semi-circular hook bars 242 that are welded to the connection nodes of the geogrids 241 and are obliquely inserted downward at 45°;

[0058] Specifically, during use, through the geogrid 5041, the roadbed support in the horizontal and vertical directions can be ensured. The semi-circular hook bars 242 being obliquely inserted downward at 45° can prevent the overall slippage and collapse of the road surface.

[0059] Example 4: As Figure 1 and Figure 4 shown, the laying thickness of the sand and gravel cushion layer 3 is 20 - 40 cm, including

[0060] a gravel filter layer 31, which is laid at the bottom of the sand and gravel cushion layer 3 and is formed by compacting fine gravel aggregates;

[0061] an artificially graded sand and gravel cushion layer 32, which is laid on the upper side of the gravel filter layer 31; including medium sand (particle size 0.25 - 0.5 mm) with a volume ratio of 20 - 25%, crushed stone (particle size 3 - 9 mm) with a volume ratio of 25 - 35% and having a particle size of 5 - 20 mm, and pebbles (particle size 2 - 4 mm) with a volume ratio of 45 - 55% and having a particle size of 20 - 40 mm. During laying, the construction plan of "laying sand and stone in layers and compacting in thin layers" is adopted for laying;

[0062] Specifically, during use, the gravel filter layer 31 is used to play a filtering role, and the artificially graded sand and gravel cushion layer 32 is used to enhance the stability of the roadbed structure, avoiding roadbed deformation during use.

[0063] When the roadbed structure of the present utility model is in use:

[0064] 1. The roadbed structure adopts a method of combining drainage, isolation, and support, guiding the groundwater under the roadbed into the side ditch outside the roadbed along the blind ditch for drainage;

[0065] 2. The gelled gravel mixture layer and the geomembrane layer isolation layer are provided in the roadbed, effectively preventing capillary water from carrying salt ions to erode the roadbed structure, being beneficial to improving the water stability of the roadbed structure, and at the same time effectively reducing the occurrence of roadbed diseases in the saline soft soil environment;

[0066] 3. A sand-gravel cushion layer is provided in the subgrade, which can prevent the hazards caused by the frost heave and salt expansion of saline soil;

[0067] 4. The anti-subsidence support layer composed of a geogrid layer in the subgrade can support the road surface when the saline soil undergoes salt expansion and subsidence, improve the service life of the road surface, and has a good effect in reducing the maintenance cost and upkeep cost of the road surface. It has the advantages of good anti-subsidence and anti-saline soil erosion effects, strong applicability to saline soil under extreme temperature difference conditions, and good subgrade stability.

[0068] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A roadbed structure, in a trapezoidal structure, characterized in that: The roadbed structure includes Asphalt concrete surface (1); An anti-dissolution support layer (2) is laid on the lower side of the asphalt concrete surface layer (1); A gravel cushion layer (3) is laid on the lower side of the anti-dissolution support layer (2); A gravel layer (4) is laid on the lower side of the gravel cushion layer (3), and a blind ditch (5) is also opened in the gravel layer (4); The saline soil layer (6) is laid on the lower side of the sand and gravel layer (4) and is located on the upper side of the roadbed bearing layer (7).

2. A roadbed structure according to claim 1, characterized in that: The asphalt concrete surface layer (1) comprises A fine-grained densely mixed asphalt concrete layer (11) is laid on the bottom of the asphalt concrete surface layer (1); A medium-grained densely distributed asphalt concrete layer (12) is laid on top of the fine-grained densely distributed asphalt concrete layer (11); The coarse-grained densely distributed asphalt concrete layer (13) is laid on top of the medium-grained densely distributed asphalt concrete layer (12).

3. A roadbed structure according to claim 2, characterized in that: The particle size of the fine-grained densely distributed asphalt concrete layer (11) is less than the particle size of the medium-grained densely distributed asphalt concrete layer (12) and less than the particle size of the coarse-grained densely distributed asphalt concrete layer (13).

4. A roadbed structure according to claim 1, characterized in that: The anti-dissolution support layer (2) comprises A cemented sand-gravel mixture layer (21) is laid on the bottom of the anti-dissolution support layer (2); A geomembrane layer (22) is laid on top of the cementitious sand-gravel mixture layer (21); A geotextile layer (23) is laid on top of the geomembrane layer (22); The geogrid layer (24) is laid on top of the geotextile layer (23).

5. A roadbed structure according to claim 4, characterized in that: The geogrid layer (24) comprises a plurality of geogrids (241), and hooked steel bars (242) inserted obliquely downward are arranged at the connection nodes of the geogrids (241).

6. A roadbed structure according to claim 1, characterized in that: Edge wrapping layers (8) are also provided on the inclined surfaces on both sides of the roadbed structure.

7. A roadbed structure according to claim 1, characterized in that: A drainage ditch (9) is also provided at the slope foot of the roadbed structure, and the drainage ditch (9) is compatible with the blind ditch (5).

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