Graded broken stone and foam light soil roadbed partition structure and construction method

Abstract

The invention discloses a gap graded broken stone and foam light soil roadbed partition structure and a construction method, and belongs to the technical field of roadbed engineering, the gap graded broken stone and foam light soil roadbed partition structure comprises a partition layer arranged between a roadbed base and a roadbed, and an inverted filter layer is arranged between the partition layer and the roadbed; the partition layer comprises a foam light soil structure layer on the lower portion and a partition gravel layer on the upper portion, and water storage tanks are built on the two sides of the junction of the foam light soil structure layer and the partition gravel layer; the width of the partition layer is larger than that of the roadbed, and the width of the inverted filter is equal to that of the top of the partition gravel layer. The foam light soil structure layer and the partition gravel layer are jointly used as the partition layer, so that water and salt can be prevented from moving upwards to the roadbed, and water in the roadbed can be prevented from infiltrating into a roadbed base; the water storage tank is arranged at the junction of the foam light soil structure layer and the partition gravel layer, water is collected, and in the non-rainfall period, the water in the water storage tank can be discharged under the transpiration effect.

Description

Technical Field

[0001] The invention belongs to the technical field of roadbed engineering, and in particular relates to a roadbed partition structure of discontinuously graded crushed stone and foamed lightweight soil and a construction method. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] In the arid northwest region, saline soil is widely distributed, which poses a huge challenge to highway construction in the arid northwest region. For highway projects, the main diseases caused by saline soil are: (1) salt expansion causes the roadbed and pavement to swell and crack, and the shoulders and slopes to loosen and erode; (2) after being flooded, the strength and stability of the roadbed are sharply reduced, and dissolution and deformation occur; (3) the salt expansion, corrosion, dissolution, frost heave and mudslide of the roadbed are aggravated; (4) it has an erosive effect on materials such as cement, asphalt, and steel.

[0004] In the prior art, geomembranes are usually laid for separation during roadbed construction. Geomembranes are impermeable and can block salt, but they also lead to long-term accumulation of water and salt underneath, which can form gas accumulation and create a weak interlayer. In addition, when laying geomembranes, there is also the concern that the geomembrane may be damaged, or that the quality of on-site construction workers may affect the quality of the construction personnel, resulting in poor separation effect and affecting its long-term separation effect. Summary of the invention

[0005] In view of the above problems, the present invention provides a partition structure of a graded gravel and foamed lightweight soil roadbed and a construction method. By using the foamed lightweight soil structure layer and the partition gravel layer together as the partition layer, it is not only possible to isolate the water and salt from migrating upward to the roadbed due to the combined action of capillary water and salt migration, but also possible to prevent the moisture inside the roadbed soil and under the action of surface runoff from infiltrating into the roadbed base, thereby preventing the moisture from infiltrating into the saline soil and causing salt melting, salt swelling and other diseases; water storage tanks are arranged at both ends of the junction of the foamed lightweight soil structure layer and the partition gravel layer to collect the moisture; and since the width of the partition gravel layer is greater than the width of the roadbed, there is only a filter layer above the water storage tank, and during non-rainfall periods, the moisture in the water storage tank can be discharged under the action of transpiration.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, a discontinuous graded crushed stone and foam lightweight soil roadbed partition structure is provided, which is arranged between a roadbed base and a roadbed, wherein the roadbed base is formed by clearing the original ground surface, comprises a partition layer arranged between the roadbed base and the roadbed, and an anti-filter layer is arranged between the partition layer and the roadbed;

[0008] The isolation layer includes a lower foam light soil structure layer and an upper isolation gravel layer, and water storage tanks are built on both sides of the junction of the foam light soil structure layer and the isolation gravel layer;

[0009] The width of the barrier layer is greater than the width of the roadbed, and the width of the filter layer is equal to the width of the top of the barrier gravel layer.

[0010] Preferably, an iron support skeleton net is arranged above the water storage tank and is located at the bottom of the partition gravel layer, and the water storage tank is built on the top of the foam lightweight soil structure layer.

[0011] Preferably, the top of the foamed lightweight soil structure layer should be set with a horizontal slope of 2%-5%, and the internal porosity of the foamed lightweight soil should be in the range of 44% to 54%.

[0012] Preferably, the partition gravel layer uses discontinuous graded gravel to increase the gaps in the partition gravel layer, prevent water and salt in the foam lightweight soil structure layer from penetrating upward into the roadbed, and when it is not raining, allow the water in the water storage tank to be discharged upward from the partition layer under transpiration.

[0013] Preferably, drainage ditches are arranged on both sides of the roadbed, and the drainage ditches are arranged before the original ground at the location of the roadbed base is processed.

[0014] In a second aspect, a construction method of the above-mentioned discontinuous graded crushed stone and foam lightweight soil roadbed partition structure is provided, and the specific steps include:

[0015] S1. Build drainage ditches on both sides of the original ground to be treated;

[0016] S2. Processing the original ground where the roadbed base is located;

[0017] S3. Anti-corrosion of roadbed base;

[0018] S4. Measure and lay out on the roadbed base;

[0019] S5. Lay a barrier layer and a filter layer on the roadbed base;

[0020] In S5, it is necessary to first lay a foamed lightweight soil structure layer on top of the roadbed, and set a 2%-5% cross slope on the top of the foamed lightweight soil structure layer; and build water storage tanks at both ends of the top of the foamed lightweight soil structure layer, and then lay a partition gravel layer, and set a filter layer on the top of the partition gravel layer;

[0021] S6. Carry out roadbed filling;

[0022] S7. Carry out road shoulder protection;

[0023] S8. Improve the drainage system.

[0024] Preferably, in S2, the salt crust soil, vegetation and saline soil on the surface of the roadbed base need to be removed. After the removal, the roadbed base should be made into a transverse slope and backfilled and compacted.

[0025] Preferably, when filling the roadbed in S6, it is necessary to load, level and compact the materials in layers until the roadbed is completed. The filler is spread and roughly leveled by a bulldozer, and then finely leveled by a grader. The filler is then measured to determine the virtual paving thickness and ensure the filling thickness.

[0026] Preferably, in S7, a mud-bonded gravel reinforcement method is used to reinforce the road shoulder so that the road shoulder can remain stable under rain erosion.

[0027] Compared with the prior art, the present invention has the following advantages and positive effects:

[0028] (1) Before clearing the surface, the present invention should first set up a drainage system around the roadbed to prevent rainwater from invading the roadbed base and causing salt dissolution; by treating the original ground, removing the surface saline-alkali soil, leveling and drying it, and then rolling it; and applying insulating materials on the rolled ground to prepare for the later anti-erosion of the roadbed.

[0029] (2) The present invention uses a foamed lightweight soil structure layer and a partition gravel layer as a partition layer, which can not only isolate the water and salt from migrating upward to the roadbed due to the combined action of capillary water and salt migration, but also prevent the water inside the roadbed soil and the surface runoff from infiltrating into the roadbed base, thereby preventing the water from infiltrating into the saline soil and causing salt melting, salt swelling and other diseases; water storage tanks are built at both ends of the junction of the foamed lightweight soil structure layer and the partition gravel layer to collect the water; and because the width of the partition gravel layer is greater than the width of the roadbed, there is only a filter layer above the water storage tank. During non-rainfall periods, the water in the water storage tank can be discharged under the action of transpiration.

[0030] (3) The present invention provides a filter layer between the partition layer and the roadbed to filter the water that permeates downward from the roadbed, thereby preventing the gaps in the partition gravel layer from being blocked and preventing the water in the water storage tank from being unable to be discharged through transpiration.

[0031] (4) The present invention uses a foam lightweight soil structure layer and a partition gravel layer, so there is no need to lay a composite geomembrane as a partition layer, thereby avoiding the use of a composite geomembrane that will cause long-term water and salt accumulation, gas accumulation, and weak interlayers. There is no need to worry about the damage of the geomembrane, or the poor partition effect caused by the poor quality of the construction workers leading to the unsealed laying.

[0032] (5) The foamed lightweight soil used in the present invention has excellent water stability, shrinkage performance, and resistance to freeze-thaw cycles, thereby providing a longer-term salt erosion resistance function for the road structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0034] Figure 1 is a schematic diagram of a partition structure of Embodiment 1 or Embodiment 2 of the present invention;

[0035] Figure 2 is a schematic diagram of a water storage tank according to Embodiment 1 or Embodiment 2 of the present invention;

[0036] Figure 3 is an overall construction flow chart of Embodiment 2 of the present invention;

[0037] In the figure:

[0038] 1. Roadbed base; 2. Partition layer; 21. Foam lightweight soil structure layer; 22. Partition gravel layer; 23. Water storage tank; 3. Filter layer; 4. Roadbed; 5. Drainage ditch. DETAILED DESCRIPTION

[0039] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0040] The present invention is described in detail below in conjunction with the accompanying drawings.

[0041] Example 1

[0042] This embodiment discloses a roadbed partition structure of broken-graded crushed stone and foamed lightweight soil, such as Figure 1 As shown, it includes a barrier layer 2 arranged between the roadbed base 1 and the roadbed 4. The barrier layer 2 is laid at the bottom of the roadbed 4, and its main purpose is to prevent the salt and part of the water in the roadbed base 1 from invading the roadbed 4 upward. An anti-filtration layer 3 is arranged between the barrier layer 2 and the roadbed 4, and its main purpose is to prevent the water inside the soil of the roadbed 4 from seeping downward, bringing the soil into the barrier layer 2 and blocking the barrier layer 2. Drainage ditches 5 are arranged on both sides of the roadbed 4, and are arranged before the original ground treatment at the location of the roadbed base to prevent rainwater from invading the roadbed base and causing salt dissolution during the surface clearing process. It can be understood that when the roadbed 4 and the road surface above it are completed and put into use, the drainage ditch 5 serves as a drainage system, and the rainwater on the road surface on the top of the roadbed will eventually be collected in the drainage ditch 5.

[0043] like Figure 1As shown, the barrier layer 2 is divided into two parts, the lower barrier layer is a foam lightweight soil structure layer 21, which is made of foam lightweight soil, and the upper barrier layer is a barrier gravel layer 22, which is made of discontinuous graded gravel. Figure 1 As shown, a water storage tank 23 is built between the foam lightweight soil structure layer 21 and the partition gravel layer 22, and the water storage tank 23 is arranged on both sides of the junction of the foam lightweight soil structure layer 21 and the partition gravel layer 22. Specifically, the water storage tank 23 is arranged on the top of the foam lightweight soil structure layer 21. It should be noted that the top of the foam lightweight soil structure layer 21 should be set with a horizontal slope of 2%-5%, so that the water on the top of the foam lightweight soil structure layer 21 flows into the water storage tanks on both sides.

[0044] like Figure 2 As shown, a semicircular iron support skeleton net is also arranged above the water tank 23. The iron support skeleton net is arranged at the bottom of the partition gravel layer 22. Its function is to prevent the larger-sized gravel in the discontinuous graded gravel from entering the water tank and ensure sufficient water storage space. It is understandable that the water tank 23 can be made of cast-in-place concrete. First, the template of the water tank 23 is supported, and the two ends of the iron support skeleton net are arranged in the template of the water tank 23, and finally cast together. In some embodiments, it can also be constructed by factory prefabrication and on-site assembly.

[0045] When water seeps down from the soil of the upper roadbed 4 and the surface runoff, it will first pass through the filter layer 3 and enter the partition gravel layer 22. When it reaches the top of the foam lightweight soil structure layer 21, due to the transverse slope of the top of the foam lightweight soil structure layer 21, the water is collected and stored in the water storage tanks 23 on both sides.

[0046] It can be seen that in this embodiment, the role of the isolation layer 2 is not only to isolate the soil below the roadbed base 1, and prevent the water and salt from migrating upward due to the combined action of capillary water and salt migration, but also to prevent the water inside the soil of the upper roadbed 4 and the surface runoff from infiltrating into the roadbed base, preventing the water from infiltrating into the saline soil and causing salt melting, salt swelling and other diseases, and having the function of collecting water.

[0047] like Figure 1 As shown, the width of the barrier layer 2 is greater than the width of the roadbed 4, and the width of the filter layer 3 is equal to the width of the barrier layer 2. To be precise, the width of the filter layer 3 is equal to the top width of the barrier gravel layer 22. During rainfall, most of the rainwater on the road surface at the top of the roadbed will be discharged into the drainage ditch 5, and a small amount of rainwater will pass through the filter layers 3 on both sides of the roadbed 4, penetrate into the barrier gravel layer 22, and be collected by the water storage tank 23. Here, the function of the filter layer 3 is also to prevent rainwater from infiltrating into the barrier gravel layer 22 with soil, and to prevent the barrier gravel layer 22 from being blocked.

[0048] In this embodiment, even if a very small amount of moisture and salt migrates upward to the top of the foam lightweight soil structure layer 21, since the top of the foam lightweight soil structure layer 21 is the partition gravel layer 22, the gap is larger than the graded gravel, making it difficult for the salt to continue to migrate upward and cannot further penetrate into the roadbed. It will stop at the junction of the foam lightweight soil structure layer 21 and the partition gravel layer 22, thereby preventing the salinization of the road surface.

[0049] In this embodiment, the partition gravel layer 22 can not only be isolated from the foam lightweight soil structure layer 21, but also the water and salt migrate upward due to the combined action of capillary water and salt migration. Since the northwest region has little rainfall, sufficient sunshine, high temperature and is very dry; in the vertical direction, there is only the filter layer 3 above the partition gravel layer 22 on the top of the water storage tank 23, without the obstruction of the roadbed 4. When it is not raining, the water collected in the water storage tank 23 does not need to be discharged specifically. Under the conditions of light, high temperature and dryness, it will eventually be emitted from the gaps in the partition gravel layer 22 upwards and from the part other than the overlap between the partition gravel layer 22 and the roadbed 4 under the action of transpiration.

[0050] In addition, the partition crushed stone layer 22 uses discontinuous graded crushed stone, which is more convenient to obtain, simpler to prepare, more cost-effective, and has large internal voids than graded crushed stone. By setting the partition crushed stone layer 22 and the foam lightweight soil structure layer 21, it is no longer necessary to control the salt content of the water quality required for the roadbed backfill material, because the salt and water in the roadbed base 1 cannot penetrate into the roadbed 4.

[0051] In this embodiment, the thickness of the partition gravel layer 22 is 30cm, of which the maximum particle size is 50mm, which can be divided into 10-20mm and 30-50mm, and the content of soil less than 0.5mm is not more than 5%. The filter layer adopts geotextile with permeability function, and its physical and mechanical properties should meet the corresponding requirements. It can also adopt medium and coarse sand, and the mud content should not be more than 3%, and the thickness is 10-15cm. The mesh size of the iron support skeleton net is 3cm.

[0052] In this embodiment, the foam lightweight soil structural layer 21 adopts foam lightweight soil, and the thickness of the foam lightweight soil structural layer is 0.5m. In order to achieve the purpose of the foam lightweight soil not only playing a partition effect but also having a lightweight characteristic, and also reducing the cost, the porosity range of the foam lightweight soil needs to be controlled within 44% to 54%; when preparing the foam lightweight soil, the foam lightweight soil mix ratio is 60 to 150g of aeolian sand, 60 to 150g of oil sludge pyrolysis residue, foam to slurry volume ratio of 0.8:1 to 1.0:1, foaming agent dilution multiple of 35 to 50, water-solid ratio of 0.3 to 0.33, and stirring time of 90s to 120s.

[0053] The location of the barrier layer should be noted: the roadbed should not be affected by the salt and moisture in the lower part to ensure its strength and stability, and at the same time, the project cost and construction difficulty should not be increased too much. On Class II and lower highways, the top surface of the barrier layer should be controlled at 0.8-1.5m below the edge of the shoulder, and at the same time, it must meet the freezing depth requirements and be more than 20cm higher than the long-term surface water level or the ground. In the reconstructed section where the roadbed replacement and barrier measures are comprehensively handled, the top surface of the barrier layer should be located at the lower edge of the replacement or the lower part of its interlayer. In the excavated section, the barrier layer should be at least 30cm below the mature layer of the newly paved road surface, or more than 20cm above the ditch water level.

[0054] In this embodiment, the roadbed base 1 needs to be formed through the steps of clearing, filling, compaction, etc. Specifically, before clearing, it is necessary to build drainage ditches 5 on both sides of the ground to be cleared to drain the water from the ground to be cleared and its two sides, so as to prevent the occurrence of saline soil diseases in the cleared part during the ground clearing process, and also to prevent the occurrence of salt dissolution when rainwater invades the roadbed 4 during the later construction of the roadbed.

[0055] After that, the surface clearing operation is carried out to remove the salt crust soil, vegetation and saline soil on the surface of the roadbed base 1. The removal thickness should be controlled in accordance with relevant specifications. For special sections, the removal depth can be changed to prevent the roadbed base 1 from being eroded by saline soil again. The cleared roadbed base 1 should be made into a horizontal slope, and backfilled and compacted in accordance with the requirements of the current specifications and standards. It needs to be dried and leveled before compaction. The compaction degree of the roadbed base 1 should not be less than 90%. A small vibrating roller can be used to statically press the cleaned site 2-3 times to avoid damage to the soil structure. If there are pits, holes, holes, etc. on the original ground, after removing the sediment, qualified fillers should be backfilled and compacted in layers, and the compaction degree should meet the requirements. If there are springs or outcropping groundwater, effective drainage measures should be taken according to the design requirements before the embankment can be filled. When the foundation is cultivated land, loose soil, rice fields, lakes and ponds, soft soil, high liquid limit soil, etc., it should be treated according to the design requirements, and effective treatment measures should also be taken for the locally soft and elastic parts. When the groundwater level is high, it should be treated according to the design requirements.

[0056] The surface of the roadbed base 1 that has been cleaned and compacted is coated with insulating materials. In this embodiment, paint and other related insulating materials are used for spraying to prevent corrosion and prepare for the later anti-erosion of the roadbed 4. Only then can the construction steps such as laying out the lines, laying the partition layer, the filter layer, and the roadbed be carried out.

[0057] Before filling the roadbed 4, that is, before transporting materials, the filling material in the excavation area needs to be tested and can only be used after passing the test; when filling the roadbed 4, the filling material is roughly spread and leveled by a bulldozer, and then finely leveled by a grader, and then the filling material is measured to determine the virtual spreading thickness and ensure the filling thickness.

[0058] Specifically, the unloading density is calculated based on the loose paving thickness of each layer of 30 cm. The width of the embankment fill on each side should be 50 cm greater than the design width of the fill layer (e.g. Figure 1 As shown, the overall width of the roadbed 4 must be smaller than the width of the partition gravel layer 22), and the compacted width must not be less than the designed width to ensure that the roadbed edge has sufficient compaction after the roadbed slope is trimmed. Unloading is carried out from far to near. After one layer of material is unloaded, unloading stops and the paving and leveling stage begins.

[0059] After a layer of filler is loaded, the loader is used to initially spread the loose layer thickness of 30cm, and the filler is rolled back and forth after the initial leveling to complete the initial compaction. Then the grader is used to level it. After each layer is initially leveled, a certain road humps are formed to facilitate drainage. Manual leveling is used for corners that cannot be reached by machinery.

[0060] A large-tonnage vibratory roller is used to roll the leveled fill surface. Static compaction is used for the initial compaction, and then it is changed to vibration compaction. The number of compaction passes is determined by experiments. Frog-type rammers are used to handle corners that cannot be reached by machinery or where the compaction machinery cannot meet the requirements.

[0061] The height control of the roadbed needs to consider factors such as hydrogeology, the height of capillary water action, the degree of salinization of the soil itself, and the depth of salt expansion. Among these factors, the depth of salt expansion must be given priority consideration. This depth has a critical value, namely the critical depth, which is the depth at which the sulfate-containing soil is in a relatively stable state. According to the principle of salt expansion, the critical depth of salt expansion is controlled to be about 150-160cm below the top surface of the road surface. In addition to the critical depth, the salt content of the filler must also be controlled. In this embodiment, the maximum particle size of the material used for roadbed filling is 20mm, and the content of particles with a particle size below 0.5mm shall not exceed 5%, and saline soil shall not exist.

[0062] After the roadbed 4 is filled, the surface layer and shoulder structures can be constructed; due to the corrosiveness of the saline soil itself, the shoulder and the slope will become loose, and may also be eroded by rainwater, which to a certain extent accelerates the damage rate of the shoulder. Once the shoulder is damaged, it will have an adverse effect on the structural stability of the roadbed, so effective protective measures should be taken for the shoulder and the slope. In this embodiment, in combination with the actual situation, the mud-bonded gravel reinforcement method is selected to reinforce the roadbed. The thickness of the shoulder after reinforcement is 20 cm, and the compaction degree reaches 97%, so that the shoulder can remain stable under rainwater erosion.

[0063] Finally, the drainage system is improved; water has a great impact on saline soil roadbed. In order to avoid water accumulation in the roadbed and its vicinity, the road arch cross slope is used to drain water out of the roadbed, and the drainage ditch 5 is connected to the culvert to form a complete drainage system to ensure smooth water flow.

[0064] Example 2

[0065] This embodiment discloses a construction method of a discontinuity graded crushed stone and foamed lightweight soil roadbed partition structure, which uses a discontinuity graded crushed stone and foamed lightweight soil roadbed partition structure disclosed in Example 1. Figure 3 As shown, the specific steps include:

[0066] S1. Build drainage ditches on both sides of the original ground to be treated;

[0067] Drainage ditches are built on both sides of the original ground to be treated to drain water from the ground to be cleaned and its two sides, so as to prevent saline soil diseases from occurring in the cleaned part during the ground cleaning process.

[0068] S2. Processing the original ground where the roadbed base is located;

[0069] During the treatment, the ground surface should be cleared first, and the salt crust, vegetation and saline soil on the surface of the roadbed base should be removed. The removal thickness should be controlled in accordance with relevant specifications. For special sections, the removal depth can be changed to prevent the roadbed base from being eroded by saline soil again. The roadbed base formed after the removal work is completed should be made into a horizontal slope, and backfilled and compacted in accordance with the requirements of the current specifications and standards. The compaction degree of the roadbed base should not be less than 90%.

[0070] S3. Anti-corrosion of roadbed base;

[0071] The ground that has been cleared and compacted is coated with insulating materials and anti-corrosion work is carried out.

[0072] S4. Measure and lay out on the roadbed base;

[0073] After the above work is completed, the center pile of the roadbed will be restored in time, the center line of the entire line will be connected, the filling side line piles will be determined, and lime will be sprinkled on the center line of the line, the filling side line and the loose laying height will be marked to control the fill thickness.

[0074] S5. Lay a barrier layer and a filter layer on the roadbed base;

[0075] When laying the partition layer, the foam lightweight soil structure layer is laid first, and a 2%-5% horizontal slope is set on the top of the foam lightweight soil structure layer. Water storage tanks are built at both ends of the top of the foam lightweight soil structure layer, and then the partition gravel layer is laid, and a filter layer is set on the top of the partition gravel layer.

[0076] S6. Carry out roadbed filling;

[0077] When filling the roadbed, it is necessary to load, level and compact the materials in layers until the roadbed is completed.

[0078] S7. Carry out road shoulder protection;

[0079] The roadbed was reinforced by using mud-bonded gravel. The thickness of the shoulder after reinforcement was 20cm and the compaction degree reached 97%.

[0080] S8. Improve the drainage system;

[0081] The cross slope of the road crown is used to drain water from the roadbed to the drainage ditch 5, and the drainage ditch 5 is connected to the culvert to form a complete drainage system to ensure smooth water flow.

[0082] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A roadbed partition structure of broken graded crushed stone and foamed lightweight soil, arranged between the roadbed base and the roadbed, the roadbed base is formed by clearing the original ground, characterized in that: It includes a barrier layer arranged between the roadbed base and the roadbed, and an anti-filter layer arranged between the barrier layer and the roadbed; The isolation layer includes a lower foam light soil structure layer and an upper isolation gravel layer, and water storage tanks are built on both sides of the junction of the foam light soil structure layer and the isolation gravel layer; The width of the barrier layer is greater than the width of the roadbed, and the width of the filter layer is equal to the width of the top of the barrier gravel layer.

2. A discontinuous graded crushed stone and foamed lightweight soil roadbed partition structure as claimed in claim 1, characterized in that: An iron support skeleton net is arranged above the water storage tank and is located at the bottom of the partition gravel layer. The water storage tank is built on the top of the foam lightweight soil structure layer.

3. The discontinuous graded crushed stone and foam lightweight soil roadbed partition structure as claimed in claim 1, characterized in that: The top of the foamed lightweight soil structural layer is set with a horizontal slope of 2%-5%, and the internal porosity of the foamed lightweight soil needs to meet the range of 44%-55%.

4. The discontinuous graded crushed stone and foamed lightweight soil roadbed partition structure as claimed in claim 1, characterized in that: The partition gravel layer uses discontinuous graded gravel to increase the gap between the partition gravel layer, prevent water and salt from the foam lightweight soil structure layer from penetrating upward into the roadbed, and when it is not raining, the water in the water storage tank can be discharged upward from the partition layer under the action of transpiration.

5. The discontinuous graded crushed stone and foam lightweight soil roadbed partition structure as claimed in claim 1, characterized in that: Drainage ditches are arranged on both sides of the roadbed, and the drainage ditches are arranged before the original ground at the location of the roadbed base is processed.

6. The construction method of a discontinuous graded crushed stone and foamed lightweight soil roadbed partition structure as claimed in any one of claims 1 to 5, characterized in that: The specific steps include: S1. Build drainage ditches on both sides of the original ground to be treated; S2. Processing the original ground where the roadbed base is located; S3. Anti-corrosion of roadbed base; S4. Measure and lay out on the roadbed base; S5. Lay a barrier layer and a filter layer on the roadbed base; In S5, it is necessary to first lay a foamed lightweight soil structure layer on top of the roadbed, and set a 2%-5% cross slope on the top of the foamed lightweight soil structure layer; and build water storage tanks at both ends of the top of the foamed lightweight soil structure layer, and then lay a partition gravel layer, and set a filter layer on the top of the partition gravel layer; S6. Carry out roadbed filling; S7. Carry out road shoulder protection; S8. Improve the drainage system.

7. The construction method of the discontinuous graded crushed stone and foamed lightweight soil roadbed partition structure as claimed in claim 6, characterized in that: In S2, the salt crust, vegetation and saline soil on the surface of the roadbed base need to be removed. After the removal, the roadbed base should be made into a transverse slope and backfilled and compacted.

8. The construction method of the discontinuous graded crushed stone and foamed lightweight soil roadbed partition structure as claimed in claim 6, characterized in that: When filling the roadbed in S6, it is necessary to load, level and compact the materials in layers until the roadbed is completed. The filler is spread and roughly leveled by a bulldozer, and then finely leveled by a grader. Then the filler is measured to determine the virtual paving thickness and ensure the filling thickness.

9. The construction method of the discontinuous graded crushed stone and foamed lightweight soil roadbed partition structure as claimed in claim 5, characterized in that: In S7, the road shoulder is reinforced by using a mud-bonded gravel reinforcement method, so that the road shoulder can remain stable under rain erosion.

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