Self-salt-reducing salinized soil roadbed structure and construction method

Abstract

The invention belongs to the technical field of roadbed structures, and particularly relates to a self-salt-reducing salinized soil roadbed structure and a building method, the self-salt-reducing salinized soil roadbed structure comprises a roadbed, an embankment, a lower roadbed, an upper roadbed, a pavement structure layer and a pavement which are sequentially arranged from bottom to top, and alkali removal ditches which are arranged on the roadbed and are respectively positioned on two sides of the embankment, each of the embankment and the lower roadbed comprises a plurality of salinized soil layers and a plurality of first salt discharge layers, the plurality of salinized soil layers and the plurality of first salt discharge layers are arranged in an interbedding manner, and the plurality of first salt discharge layers extend to the two sides of the embankment and the lower roadbed to be connected with each other and are connected with the inner wall of the alkali removal ditch; the multiple first salt discharge layers extend to the outer sides of the embankment and the lower roadbed to form salt discharge channels communicated with the alkali removal ditches; through mutual filling of the salinized soil and the salt discharging layer, the stability of the embankment is improved, sedimentation is reduced, self-purification of the roadbed is achieved, salt-containing filler can be converted on site, cost is saved, and the method adapts to rapid construction.

Description

Technical Field

[0001] The invention belongs to the technical field of roadbed structures, and in particular relates to a self-salting saline soil roadbed structure and a construction method. Background Art

[0002] Saline soil is widely distributed in the northwest provinces of my country. At the same time, it is affected by seasonal frozen soil activities, and the freezing depth is about 0.5m-1.0m. The soil within the freezing depth range of saline soil roadbed in seasonal frozen soil areas is accompanied by a variety of physical and chemical processes during the alternation of cold and warm seasons. After the warm season ends and the cold season begins, the surface begins to freeze, and the frozen surface develops downward. Water migrates from bottom to top toward the frozen surface. The water drives soluble salts such as sodium chloride and sodium sulfate to migrate from the base or embankment to the lower roadbed, upper roadbed, subbase or base, eroding the roadbed or pavement structure layer. At the same time, after the water and salt migrate to the vicinity of the freezing surface, as the freezing surface continues to develop downward, the soluble salt solution expands in volume after freezing, which will cause frost heave and salt heave diseases of the roadbed. After entering the warm season, the surface begins to melt, the ground temperature gradually rises, the solubility of the salt solution continues to increase, the precipitated salt crystals begin to melt, and the roadbed fill may suffer from dissolution and subsidence diseases. With the alternating changes in temperature, the roadbed undergoes repeated salt expansion, frost expansion, and dissolution, and the soil repeatedly swells and loosens, causing slope instability or deformation and damage to the roadbed and road surface. In order to alleviate and prevent the frost expansion, salt expansion, and dissolution of saline soil roadbeds in seasonally frozen areas, an effective way is to control the water and salt migration and salt phase change in the soil.

[0003] In the existing technology, saline soil roadbed faces two major problems: 1. To prevent and control salt swelling and dissolution of saline soil roadbed, two barrier methods, impermeable and permeable, are commonly used. The permeable barrier layer is paved with gravel, aeolian sand and other permeable fillers, and the thickness must be greater than or equal to the capillary water rise height of salt. Among them, the strong capillary water rise height of gravel and sand is 40-110cm, which is suitable for sections where fillers are easy to obtain; aeolian sand is 80-90cm, and it is paved at least 90cm thick as a barrier layer, which has problems such as difficult compaction control and large amount of fillers; silty and clay soils are 200-400cm, and when used as fillers, they will be salinized due to salt migration, resulting in the failure of the barrier function. The impermeable barrier layer uses waterproof geotextiles, etc. When a gravel horizontal drainage layer is set, it is easy to be punctured by granular materials during construction and operation, and there are capillary barrier problems; when no gravel horizontal drainage layer is set, it is easy to be swollen or broken by the surrounding soil, and there are also capillary barrier problems. In addition, the barrier layer blocks the upward movement of salt, causing the accumulation of soluble salts in the lower part, causing serious damage from salt expansion in the cold season.

[0004] 2. In addition, the soil layers in the northwest are mostly strong and medium saline soils. There is a shortage of benign fillers when building roads. The current replacement method is mostly used, which uses a large amount of soil and discards a large amount of soil. Using local materials can reduce costs and facilitate green road construction, but direct road construction on saline soil needs to solve problems such as seasonal frozen soil, salinization and secondary salinization. These diseases are mostly caused by surface water infiltration and underground capillary water migration. Traditional water isolation and drainage technologies have capillary barrier problems. When filling the roadbed on-site with saline soil, the key is to control the salt content of the earth roadbed below the limit to ensure the stability of the filling layer and slope and avoid deformation and damage.

[0005] In view of the difficulties existing in the above-mentioned background technology, technical experts in this field have innovatively developed a saline soil roadbed structure with self-salinity reduction function and a corresponding construction method in the design and construction of highways in many saline soil areas in the northwest. Summary of the invention

[0006] The present invention aims to provide a self-salting saline soil roadbed structure and construction method, which are used to solve the capillary barrier problem of seasonal frozen soil roadbed water isolation and drainage technology in saline soil areas, and to solve the problem of resource utilization of a large amount of saline soil waste.

[0007] To achieve the above object, the present invention is implemented according to the following technical solutions: A self-salting saline soil roadbed structure comprises a roadbed, an embankment, a lower roadbed, an upper roadbed, a pavement structure layer and a pavement arranged in sequence from bottom to top, and a de-alkali ditch arranged on the roadbed and respectively located on both sides of the embankment, the embankment and the lower roadbed both comprise multiple layers of saline soil layers and multiple layers of first salt-draining layers, the multiple layers of saline soil layers and the multiple layers of first salt-draining layers are alternately arranged, the multiple layers of the first salt-draining layers extend to both sides of the embankment and the lower roadbed, are connected to each other and to the inner wall of the de-alkali ditch, and the multiple layers of the first salt-draining layers extend to the outside of the embankment and the lower roadbed to form a salt-draining channel connected to the de-alkali ditch.

[0008] Furthermore, both ends of the first row of salt layers located above extend to the outside of both ends of the adjacent first row of salt layers below and are connected, and both ends of the first row of salt layers at the bottom extend to the inside of the two de-alkali trenches and are connected to their inner walls.

[0009] Furthermore, a waterproof membrane is provided on the upper side of the topmost first row of salt layer, and a second row of salt layer is provided between the waterproof membrane and the upper roadbed.

[0010] Furthermore, the first row of salt layers includes two second paving layers arranged at intervals, and a first paving layer overlapped at both ends of the upper sides of the two second paving layers, and the second paving layer is overlapped with the first paving layer with a width of 0.1-0.2 m at a distance of 0.5 m from the slope.

[0011] Furthermore, the first paving layer and the second paving layer are both made of reinforced wicking geotextiles, and the vertical layer spacing between the multiple layers of the first row of salt layers is 0.6m.

[0012] Furthermore, a salt storage device is embedded in the upper side of the saline soil layer, and one group of the salt storage device is arranged every 20m in the length direction of the saline soil layer contained in the lower roadbed, and one group of the salt storage device is arranged every 5m in the length direction of the saline soil layer contained in the embankment. One group of the salt storage devices is provided with two spaced apart in the width direction of the saline soil layer, and both of the two salt storage devices are 0.3-0.4m away from the slope, and the two salt storage devices are connected to the lower side of the first row of salt layers, and the salt storage devices use salt storage bags.

[0013] Furthermore, the saline soil layer contained in the lower roadbed is weakly saline soil, and the saline soil layer contained in the embankment is moderately saline soil.

[0014] Furthermore, the upper roadbed is filled with 5% limestone or natural gravel.

[0015] A method for constructing a self-salting saline soil roadbed structure, the method comprising the following steps: A. Roadbed treatment, the specific steps are as follows: S1. Use an excavator to clear the roadbed, ensuring that the treatment depth is not less than 0.3m, and the treatment width includes the width of the alkali removal ditch; S2. Use rollers and graders to compact and level the roadbed to ensure that the flatness of the base meets the specifications.

[0016] B. Construction of embankment and lower roadbed, the specific steps are as follows: S1. Construction of embankment: The pole method is used to measure and ensure that the loose thickness of each layer of saline soil using medium saline soil does not exceed 0.3m; After each layer of saline soil layer using medium saline soil is filled, a small groove inclined along the route direction is reserved on its upper surface. The depth of the small groove is 1-2 cm. The upper side of the small groove is flush with the upper surface of the saline soil layer. The length and width of the small groove are adapted to the size of the salt storage device. The salt storage device is embedded in the reserved small groove, and the upper port of the salt storage device is flush with the upper surface of the saline soil layer using medium saline soil; A first row of salt layers is laid on the upper side of each layer of saline soil using medium saline soil, and the sides of the first row of salt layers located at the bottom extend to the inside of the two de-alkali trenches and are connected to the inner walls thereof; When laying the first row of salt layer, first lay a second paving layer on both ends of the saline soil layer, and then lay a first paving layer in the middle of the upper side of the two, with an overlap width of 0.1-0.2m; Repeat the above steps; Both ends of the first row of salt layer in the upper layer are overlapped on the first row of salt layer in the lower layer to form a continuous salt discharge channel, thus completing the construction of embankment 3.

[0017] S2. Construction of lower roadbed: The pole method is used to measure and ensure that the loose thickness of each layer of saline soil using weak saline soil does not exceed 0.3m; After each layer of saline soil layer made of weak saline soil is filled, a small groove inclined along the route direction is reserved on its upper surface. The depth of the small groove is 1-2 cm. The upper side of the small groove is flush with the upper surface of the saline soil layer made of weak saline soil. The length and width of the small groove are adapted to the size of the salt storage device. The salt storage device is embedded in the reserved small groove, and the upper port of the salt storage device is flush with the upper surface of the saline soil layer using weakly saline soil; A second row salt layer is laid on the uppermost saline soil layer of weakly saline soil, and then a waterproof membrane is laid on the upper surface of the second row salt layer. Subsequently, a second row salt layer is laid on the upper surface of the waterproof membrane. The waterproof membrane is a continuous and uninterrupted single sheet, and both sides extend to the lower second row salt layer and overlap it; When laying the first row of salt layer, first lay a second paving layer on both ends of the saline soil layer, and then lay a first paving layer in the middle of the upper side of the two, with an overlap width of 0.1-0.2m; Both ends of the upper second-row salt layer are overlapped on the next second-row salt layer, and both ends of the lower second-row salt layer are overlapped on the next first-row salt layer, thus completing the construction of the lower roadbed.

[0018] C. Construction of roadbed, pavement structure layer and pavement. The specific steps are as follows: S1. After the lower roadbed is laid, 5% lime soil, cement soil or natural gravel is used to fill the upper roadbed; S2. After the construction of the upper roadbed is completed, it shall be maintained according to the prescribed maintenance period; S3. After the maintenance period, the pavement structure layer and pavement are paved and maintained in accordance with the specifications.

[0019] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention fills the saline soil layer and the first row of salt layers in the form of interlayers, and utilizes the high permeability, high strength, high matrix suction, lateral constraint, and tensile membrane effect of the salt layer to improve the overall structural stability of the embankment, reduce uneven bulging and settlement, and at the same time, each first row of salt layers has the effect of diffusion stress. The additional stress at the bottom of the embankment of the first row of salt layers and the interlayer of saline soil is less than the additional stress of the traditional single fill layer. The interlayer structure has a small settlement after construction, and the matrix suction of the first row of salt layers to water is much greater than that of saline clay, which can effectively absorb the soluble salt solution inside the roadbed. The salt solution can be effectively introduced into the de-alkali ditch through the drive of the evaporation section, thereby achieving the effect of self-purification of the roadbed. In terms of the method and cost of treating saline soil roadbed diseases, it has a technical breakthrough, and solves the potential harm of saline soil to the entire roadbed from the root. Compared with the roadbed filled with a traditional single fill layer, this scheme has structural advantages, is easy to construct, and is quick to pave, which is compatible with the current fast process construction technology.

[0020] 2. The multi-layer first row of salt layers plays a certain reinforcement role and improves the slope stability of the roadbed.

[0021] 3. Bury salt storage bottles or salt storage bags under the first row of salt layers in each layer to prevent the migration of a large amount of salt in the roadbed due to strong evaporation when it is sunny after heavy rain or snow, resulting in crystallized salt in the salt core wire. The one-way penetration function of the salt storage bottle or salt storage bag achieves the purpose of permanent storage.

[0022] 4. The self-salting roadbed gradually absorbs the soluble salt in the earth roadbed into the alkali drainage ditch at the foot of the roadbed through the core wire of the reinforced core-absorbing geotextile, so that the salt-containing filler that is not suitable or cannot be directly used for road construction becomes non-salting soil after 2-3 freeze-thaw and dry-wet cycles, thereby achieving self-salting of the saline earth roadbed, realizing on-site resource utilization of a huge amount of abandoned salt-containing filler, avoiding long-distance transportation and replacement of benign filler, and greatly saving construction costs.

[0023] 5. The present invention aims at salt swelling, frost swelling, dissolution and other diseases induced by water-salt migration, salt phase change and other processes in saline soil roadbed. Through the combination of structure and construction method, the soluble salt in the upper roadbed can be effectively discharged laterally from the roadbed and processed. The materials of the components involved are all common geotechnical materials with low cost, few construction steps and simple later maintenance. The construction of the entire facility is carried out simultaneously with the roadbed construction, and the long-term healthy operation effect of the highway after construction is remarkable. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a cross-sectional schematic diagram of the self-salting saline soil roadbed structure of the present invention; Figure 2 For the present invention Figure 1 Schematic diagram of the structure at A in the middle.

[0025] In the figure: 1. roadbed; 2. de-alkali ditch; 3. embankment; 4. lower roadbed; 5. upper roadbed; 6. pavement structure layer; 7. pavement; 8. saline soil layer; 9. first row of salt layer; 10. second row of salt layer; 11. waterproof membrane; 12. salt storage device; 13. first paving layer; 14. second paving layer. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0027] like Figure 1-2 As shown, a self-salting saline soil roadbed structure includes a roadbed 1, an embankment 3, a lower roadbed 4, an upper roadbed 5, a pavement structure layer 6 and a pavement 7 which are arranged in sequence from bottom to top.

[0028] Alkali removal trenches 2 are provided on both sides of the embankment 3 on the roadbed 1.

[0029] The structural heights of the embankment 3 and the lower roadbed 4 are similar, both of which include multiple layers of saline soil layers 8 and multiple layers of first-row salt layers 9 arranged alternately, that is, the saline soil layers 8 and the first-row salt layers 9 appear repeatedly at intervals, a layer of saline soil layer 8, a layer of first-row salt layer 9, another layer of saline soil layer 8 and a layer of first-row salt layer 9, and this is repeated many times.

[0030] Among them, the saline soil layer 8 contained in the lower roadbed 4 is weakly saline soil, and the saline soil layer 8 contained in the embankment 3 is medium-saline soil. In this way, on the one hand, the roadbed is stabilized, because the weakly saline soil is less affected by salt, and the problem of medium-saline soil being used for the lower roadbed 4 weakening the soil when it encounters water can be avoided; on the other hand, the support of the road surface 7 by salt expansion is reduced, and the migration of water and salt is regulated to maintain the stability of water and salt in the roadbed. In addition, it is convenient for construction, and local soil can be used to reduce costs. The construction operation of weakly saline soil is easier to control, and its advantages are prominent in remote areas.

[0031] The side of each first row salt layer 9 extends downward and covers the saline soil layer 8 below it, and finally overlaps the side of the first row salt layer 9 of the next layer; until the first row salt layer 9 of the lowest layer covers the saline soil layer 8 below it and overlaps the inner wall of the de-alkali ditch 2, a lateral salt discharge channel can be formed by overlapping the multiple first row salt layers 9 to the de-alkali ditch 2; the salt discharge channel can introduce salt into the de-alkali ditch 2. In the specific construction, the vertical layer spacing between the multiple first row salt layers 9 is at least 0.6m.

[0032] The upper side of the saline soil layer 8 is embedded with salt storage devices 12 in groups. Each salt storage device 12 is 0.3-0.4m away from the slope, and two salt storage devices 12 are connected to the lower side of the first row of salt layers 9. The salt storage devices 12 use salt storage bags; the salt storage bags are made of polyester fiber and PVA water-absorbing material, and the upper end of the salt storage bag and the lower side of the first row of salt layers 9 are sewn together with the polyester fiber by means of reinforcement materials.

[0033] The specific arrangement of the salt storage device 12 in the length direction of the roadbed is as follows: a group of salt storage devices 12 is arranged every 20 meters in the saline soil layer 8 contained in the lower roadbed 4; a group of salt storage devices 12 is arranged every 5 meters in the saline soil layer 8 contained in the embankment 3.

[0034] A waterproof membrane 11 is provided on the upper side of the first row of salt layer 9 at the top, and a second row of salt layer 10 is provided between the waterproof membrane 11 and the upper roadbed 5; the second row of salt layer 10 and the waterproof membrane 11 both extend laterally downward and cover the first row of salt layer 9 therebelow.

[0035] The first salt layer 9 is composed of a second paving layer 14 and a first paving layer 13 overlapping the second paving layer 14 .

[0036] Specifically: the second paving layer 14 is set at 0.5m away from the slope, and a 0.1-0.2m wide overlap area is set with the first paving layer 13; the overlap of the first paving layer 13 and the second paving layer 14 can effectively prevent rainwater from being sucked back into the roadbed during heavy rain. The first paving layer 13 and the second paving layer 14 are both made of reinforced core-absorbing geotextiles. The upper roadbed 5 is filled with 5% limestone or natural gravel.

[0037] The above construction method for the self-salting saline soil roadbed structure comprises the following steps: A. Roadbed 1 treatment, the specific steps are as follows: S1. Use an excavator to clear the roadbed 1, ensuring that the treatment depth is not less than 0.3m, and the treatment width includes the width of the de-alkali ditch 2; S2. Use a roller and a grader to compact and level the roadbed 1 to ensure that the flatness of the base meets the requirements of the specifications.

[0038] B. Construction of the embankment 3 and the lower roadbed 4, the specific steps are as follows: S1. Construction of Embankment 3: The pole method is used to measure and ensure that the loose thickness of each layer of saline soil layer 8 using medium saline soil does not exceed 0.3m; After each layer of saline soil 8 made of medium saline soil is filled, a small groove inclined along the route direction is reserved on its upper surface, the small groove is 1-2 cm deep, the upper side of the small groove is flush with the upper surface of the saline soil layer 8, and the length and width of the small groove are adapted to the size of the salt storage device 12; The salt storage device 12 is embedded in the reserved small groove, and the upper port of the salt storage device 12 is flush with the upper surface of the saline soil layer 8 using medium saline soil; A first row of salt layers 9 is laid on the upper side of each layer of saline soil 8 using medium saline soil, and the sides of the first row of salt layers 9 located at the bottom extend to the inside of the two de-alkali trenches 2 and are connected to the inner walls thereof; When laying the first row of salt layer 9, first lay a second paving layer 14 on both ends of the saline soil layer 8, and then lay a first paving layer 13 in the middle of the upper side of the two, with an overlap width of 0.1-0.2m; Repeat the above steps; Both ends of the first row of salt layer 9 of the upper layer are overlapped on the first row of salt layer 9 of the lower layer to form a continuous salt discharge channel, thereby completing the construction of the embankment 3.

[0039] S2, construction of lower roadbed 4: The pole method is used to measure and ensure that the loose thickness of each layer of saline soil layer 8 using weak saline soil does not exceed 0.3m; After each layer of saline soil layer 8 made of weak saline soil is filled, a small groove inclined along the route direction is reserved on its upper surface, the small groove is 1-2 cm deep, the upper side of the small groove is flush with the upper surface of the saline soil layer 8 made of weak saline soil, and the length and width of the small groove are adapted to the size of the salt storage device 12; The salt storage device 12 is embedded in the reserved small groove, and the upper port of the salt storage device 12 is flush with the upper surface of the saline soil layer 8 using weakly saline soil; A second row salt layer 10 is laid on the uppermost saline soil layer 8 of weakly saline soil, and then a waterproof membrane 11 is laid on the upper surface of the second row salt layer 10. Subsequently, a second row salt layer 10 is laid on the upper surface of the waterproof membrane 11. The waterproof membrane 10 is a continuous and uninterrupted single sheet, and both sides of the waterproof membrane 10 extend to and overlap the lower second row salt layer 10. When laying the first row of salt layer 9, first lay a second paving layer 14 on both ends of the saline soil layer 8, and then lay a first paving layer 13 in the middle of the upper side of the two, with an overlap width of 0.1-0.2m; Both ends of the upper second-row salt layer 10 are overlapped on the next second-row salt layer 10 , and both ends of the lower second-row salt layer 10 are overlapped on the next first-row salt layer 9 , completing the construction of the lower roadbed 4 .

[0040] C. Construction of the upper roadbed 5, the pavement structure layer 6 and the pavement 7, the specific steps are as follows: S1. After the lower roadbed 4 is laid, 5% lime soil, cement soil or natural gravel is used to fill the upper roadbed 5; S2. After the construction of the upper roadbed 5 is completed, it shall be maintained according to the prescribed maintenance period; S3. After the maintenance period, pavement structure layer 6 and pavement 7 are paved and maintained in accordance with the specifications.

Claims

1. A self-salting saline soil roadbed structure, comprising a roadbed (1), an embankment (3), a lower roadbed (4), an upper roadbed (5), a pavement structure layer (6) and a pavement (7) arranged in sequence from bottom to top, and a de-alkali ditch (2) arranged on the roadbed (1) and located on both sides of the embankment (3), characterized in that: The embankment (3) and the lower roadbed (4) both include multiple layers of saline soil layers (8) and multiple layers of first salt-discharging layers (9), the multiple layers of saline soil layers (8) and the multiple layers of first salt-discharging layers (9) are arranged in an alternating manner, the multiple layers of the first salt-discharging layers (9) extend to both sides of the embankment (3) and the lower roadbed (4) and are connected to each other and to the inner wall of the de-alkali ditch (2), and the multiple layers of the first salt-discharging layers (9) extend to the outer sides of the embankment (3) and the lower roadbed (4) to form a salt-discharging channel connected to the de-alkali ditch (2).

2. The self-salting saline soil roadbed structure according to claim 1 is characterized in that: The two ends of the first row of salt layers (9) located at the top extend to the outside of the two ends of the first row of salt layers (9) located at the bottom and are connected, and the two ends of the first row of salt layers (9) located at the bottom extend to the inside of the two de-alkali trenches (2) and are connected to the inner walls thereof.

3. The self-salting saline soil roadbed structure according to claim 1 is characterized in that: A waterproof membrane (11) is provided on the upper side of the uppermost first-row salt layer (9), and a second-row salt layer (10) is provided between the waterproof membrane (11) and the upper roadbed (5).

4. The self-salting saline soil roadbed structure according to claim 3 is characterized in that: The first row of salt layers (9) comprises two second paving layers (14) arranged at intervals, and a first paving layer (13) overlapped at both ends of the upper sides of the two second paving layers (14), wherein the second paving layer (14) overlaps the first paving layer (13) by 0.1-0.2 m at a distance of 0.5 m from the slope.

5. The self-salting saline soil roadbed structure according to claim 4 is characterized in that: The first paving layer (13) and the second paving layer (14) are both made of reinforced core-absorbing geotextiles, and the vertical interlayer spacing between the multiple layers of the first salt layer (13) is 0.6 m.

6. The self-salting saline soil roadbed structure according to claim 1 is characterized in that: A salt storage device (12) is embedded on the upper side of the saline soil layer (8). A group of the salt storage devices (12) is arranged every 20 m in the length direction of the saline soil layer (8) contained in the lower roadbed (4). A group of the salt storage devices (12) is arranged every 5 m in the length direction of the saline soil layer (8) contained in the embankment (3). A group of the salt storage devices (12) is provided with two spaced apart arrangements in the width direction of the saline soil layer (8). Both of the two salt storage devices (12) are 0.3-0.4 m away from the slope. The two salt storage devices (12) are connected to the lower side of the first row of salt layers (9). The salt storage devices (12) use salt storage bags.

7. The self-salting saline soil roadbed structure according to claim 7 is characterized in that: The saline soil layer (8) contained in the lower roadbed (4) is weakly saline soil, and the saline soil layer (8) contained in the embankment (3) is moderately saline soil.

8. The self-salting saline soil roadbed structure according to claim 1 is characterized in that: The upper roadbed (5) is filled with 5% limestone or natural gravel.

9. A method for constructing a self-salting saline soil roadbed structure according to claims 1 to 8, characterized in that: The method comprises the following steps: A. Roadbed (1) Treatment. The specific steps are as follows: S1. Use an excavator to clear the roadbed (1), ensuring that the treatment depth is not less than 0.3 m and the treatment width includes the width of the de-alkali ditch (2); S2. Use a roller and a grader to compact and level the roadbed (1) to ensure that the flatness of the base meets the requirements of the specification; B. Construction of the embankment (3) and the lower roadbed (4), the specific steps are as follows: S1. Construction of embankment (3): The pole method is used to measure and ensure that the loose thickness of each layer of saline soil (8) using medium saline soil does not exceed 0.3m; After each layer of saline soil (8) made of medium saline soil is filled, a small groove inclined along the route direction is reserved on its upper surface, the small groove is 1-2 cm deep, the upper side of the small groove is flush with the upper surface of the saline soil layer (8), and the length and width of the small groove are adapted to the size of the salt storage device (12); The salt storage device (12) is embedded in the reserved small groove, and the upper port of the salt storage device (12) is flush with the upper surface of the saline soil layer (8) using medium saline soil; A first row of salt layers (9) is laid on the upper side of each layer of saline soil (8) made of medium-saline soil, and the sides of the first row of salt layers (9) located at the bottom extend to the inside of the two de-alkali trenches (2) and are connected to the inner walls thereof; When laying the first row of salt layers (9), first lay a second paving layer (14) on both ends of the saline soil layer (8), and then lay a first paving layer (13) in the middle of the upper sides of the two layers, with an overlap width of 0.1-0.2m; Repeat the above steps; Both ends of the first row of salt layer (9) of the upper layer are overlapped on the first row of salt layer (9) of the lower layer to form a continuous salt discharge channel, thereby completing the construction of the embankment (3); S2. Construction of lower roadbed (4): The pole method is used to measure and ensure that the loose thickness of each layer of saline soil (8) using weak saline soil does not exceed 0.3m; After each layer of saline soil layer (8) made of weak saline soil is filled, a small groove inclined along the route direction is reserved on its upper surface, the small groove is 1-2 cm deep, the upper side of the small groove is flush with the upper surface of the saline soil layer (8) made of weak saline soil, and the length and width of the small groove are adapted to the size of the salt storage device (12); The salt storage device (12) is embedded in the reserved small groove, and the upper port of the salt storage device (12) is flush with the upper surface of the saline soil layer (8) made of weakly saline soil; A second row salt layer (10) is laid on the entire uppermost saline soil layer (8) made of weakly saline soil, and then a waterproof membrane (11) is laid on the upper surface of the second row salt layer (10). Subsequently, a second row salt layer (10) is laid on the upper surface of the waterproof membrane (11), wherein the waterproof membrane (10) is a continuous and uninterrupted single sheet, and both sides of the waterproof membrane (10) extend to and overlap the lower second row salt layer (10); When laying the first row of salt layers (9), first lay a second paving layer (14) on both ends of the saline soil layer (8), and then lay a first paving layer (13) in the middle of the upper sides of the two layers, with an overlap width of 0.1-0.2m; Both ends of the upper second-row salt layer (10) are overlapped on the next second-row salt layer (10), and both ends of the lower second-row salt layer (10) are overlapped on the next first-row salt layer (9), thereby completing the construction of the lower roadbed (4); C. Construction of the upper roadbed (5), the road surface structure layer (6) and the road surface (7), the specific steps are as follows: S1. After the lower roadbed (4) is paved, 5% lime soil, cement soil or natural gravel is used to fill the upper roadbed (5); S2. After the construction of the upper roadbed (5) is completed, it shall be maintained according to the prescribed maintenance period; S3. After the maintenance period expires, the pavement structure layer (6) and the pavement (7) are paved and maintained in accordance with the specifications.

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