CN114855519A - Saline soil roadbed laying method and roadbed structure - Google Patents

Abstract

The invention relates to a method for laying saline soil subgrade and a subgrade structure, and relates to the field of subgrade construction in saline soil areas. Lay a barrier layer; backfill the base layer on the barrier layer. The invention can solve the problem of gas accumulation in the soil under the barrier layer, and improve the safety of the saline soil roadbed.

Description

A kind of saline soil roadbed laying method and roadbed structure

technical field

The invention relates to the field of roadbed construction in saline soil areas, in particular to a method for laying saline soil roadbeds and a roadbed structure.

Background technique

Under the influence of the external environment, the water and salt in the saline soil will migrate, which will cause different degrees of diseases, such as salt heave, frost heave and pulping, which will cause the subgrade to crack, bulge and swell, thereby reducing the subgrade. Stability and strength. If the salt at the bottom of the subgrade can be effectively prevented from migrating with the groundwater or capillary water, the damage and influence caused by the migration of water and salt in the saline soil can be effectively solved. It is a commonly used treatment method for saline soil roadbed to prevent the rise of salinity by setting a barrier layer. According to the material of the barrier layer, the barrier layer can be divided into sandstone material barrier layer and geotechnical material barrier layer.

Among them, the barrier layer filled with sand and gravel materials is called sand and stone material barrier layer, but there are strict requirements for the selection and construction of sand and gravel materials; the barrier layer composed of geotextile materials is called geotechnical material barrier layer , Generally set between the embankment and the road bed or between the sub-base and the upper base. Although the geomembrane partition layer has the characteristics of good water resistance, salt isolation, easy construction and reduction of the height of the roadbed, it is impermeable due to its impermeability. It is conducive to the escape of water vapor in the roadbed, and gas accumulation will be formed under it, resulting in a weak interlayer.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for laying a saline soil roadbed and a roadbed structure, which can solve the problem of gas accumulation in the soil under the barrier layer and improve the safety of the saline soil roadbed.

For achieving the above object, the present invention provides the following scheme:

A method for laying saline soil roadbed, comprising:

The embankment is obtained by layering compaction and filling from the foundation;

laying a barrier layer longitudinally along the route on said embankment;

The base layer is backfilled on the barrier layer.

Optionally, the longitudinally laying a barrier layer along the route on the embankment specifically includes:

Lay the geomembrane of the barrier layer along the entire section of the road on the embankment;

A protective layer of the barrier layer is laid on the geomembrane.

Optionally, after laying the protective layer of the insulating layer on the geomembrane, it also includes:

Coarse-grained soil is laid on the protective layer and rolled; the thickness of the coarse-grained soil and the protective layer is less than or equal to 400mm.

A saline soil subgrade structure, the saline soil subgrade structure using the above-mentioned saline soil subgrade laying method, the saline soil subgrade structure comprising: a pavement layer, a base layer, a partition layer and an embankment;

The blocking layer is arranged between the base layer and the road embankment; the base layer is arranged between the road surface layer and the blocking layer.

Optionally, the loose thickness of the embankment is less than or equal to 300mm.

Optionally, the slope of the cross slope of the road arch of the partition layer ranges from 2% to 5%.

Optionally, the blocking layer includes a geomembrane and a protective layer laid on the geomembrane; the geomembrane is laid on the road embankment.

Optionally, the slope of the road surface layer ranges from 1:1.5 to 1:2.

Optionally, the geomembrane comprises an upper layer, an intermediate layer and a lower layer laid in sequence; the upper layer structure is a glass fiber mesh or a loosely treated glass fiber mesh; the intermediate layer is a polyethylene waterproof and breathable membrane with a pore diameter of 0.1-10 μm; The lower layer is a loosely disposed glass fiber mesh.

According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

The present invention starts from the foundation, carries out layered filling, compaction and filling to obtain road embankment; lays a barrier layer on the road embankment longitudinally along the route; and backfills the base layer on the barrier layer. By laying a barrier layer on the embankment, the problem of gas accumulation in the soil under the barrier layer can be solved and the safety of the saline soil subgrade can be improved.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings required in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some of the present invention. In the embodiments, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative labor.

Fig. 1 is the flow chart of the method for laying saline soil roadbed provided by the present invention;

Figure 2 is a schematic structural diagram of the saline soil roadbed provided by the present invention.

Symbol Description:

4- distance between geomembrane and foundation, 5- pavement layer, 6- base layer, 7- cross slope of road arch of partition layer, 8- embankment, 12- geomembrane, 14- slope of side slope, 15- protection layer.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The purpose of the present invention is to provide a method for laying a saline soil roadbed and a roadbed structure, which can solve the problem of gas accumulation in the soil under the barrier layer and improve the safety of the saline soil roadbed.

In order to make the above objects, features and advantages of the present invention more clearly understood, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

As shown in Figure 1, a method for laying saline soil roadbed provided by the present invention comprises:

Step 101: Starting from the foundation, perform layered filling, compaction and filling to obtain an embankment.

For Embankment 8 construction:

1. The borrow pit along the side of the line should be well drained according to the design requirements, and meet the environmental protection requirements.

2. Embankment 8 should be filled and compacted in layers, and the thickness of loose paving should not exceed 300mm. When rolling, it should be controlled according to the optimum moisture content ±1%, and the moisture content of coarse-grained soil should not exceed the optimum moisture content -2% to +3%. The compaction thickness of coarse-grained soil shall not exceed 300mm, the compaction thickness of aeolian sand shall not exceed 400mm, and construction shall not be carried out in rainy days.

3. For the construction of the embankment 8, it should be continuously constructed from the base treatment, and should be continuously filled to the top of the protective layer 15 of the partition layer.

4. In the viscous saline soil area with high groundwater level, construction should be carried out in summer; in the sandy saline soil area, construction should be carried out in spring and early summer; in the strong saline soil area, construction should be carried out in spring when the surface salt content is low.

5. The embankment 8 filler should strengthen the control of the salt content of the filler during the construction process, and a set of salt content tests should be done every 10,000m ³ , and should be tested at any time when the material source changes. Fillers whose test results do not meet the technical requirements of the corresponding horizon are strictly prohibited from use, and should be cleaned up immediately.

Step 102: Lay a barrier layer on the embankment along the longitudinal direction of the route; wherein, the step of laying the barrier layer on the embankment along the longitudinal direction of the route specifically includes: laying the barrier layer on the embankment along the entire section of the route. membrane; laying the protective layer of the barrier layer on the geomembrane. After laying the protective layer of the isolation layer on the geomembrane, the method further includes: laying coarse-grained soil on the protective layer and rolling it; the sum of the thicknesses of the coarse-grained soil and the protective layer is less than or Equal to 400mm.

For barrier construction:

1. Geomembrane 12 should be laid along the entire longitudinal section of the route. After spreading, it should be close to the lower bearing layer without wrinkles. When there is damage, the damaged area should be repaired with a membrane material with twice the damaged area.

2. The longitudinal lap of geomembrane 12 should press the inner width against the outer width, the lap width should not be less than 200mm, the outermost lap width should be greater than 300mm, and the horizontal lap width should be greater than 500mm.

3. After the geomembrane 12 is laid, it should be covered with the protective layer 15 in time to avoid prolonged exposure to the sun.

4. The protective layer 15 set by the geomembrane 12 and the geomembrane 12 shall not contain angular stones, and the maximum particle size of the particles within 80mm of the geomembrane 12 shall not be greater than 50mm, and shall be manually picked up if necessary. remove.

5. The filling of the protective layer 15 on the geomembrane 12 should be paved with light bulldozers or manually, and the material transporter should be unloaded or transported manually.

6. The geomembrane 12 laid in the fine-grained soil should be provided with a protective layer 15 with a thickness of not less than 0.3m. The thickness of the geomembrane 12 laid in the coarse-grained soil can be 0.1m. Medium-coarse sand or gravel can be used, the maximum particle size should not be greater than 50mm, and the content of particles with a particle size smaller than 0.075mm should not be greater than 10%.

7. After the protective layer 15 is flattened, roll it 2-3 times first, then lay a layer of coarse-grained soil, and roll it together with the upper protective layer 15. The sum of the thicknesses of the two should not exceed 400mm.

Step 103: Backfill the base layer on the insulating layer.

In the construction of expressways and first-class highways, the compaction degree of the top surface of embankment 8 to protective layer 15 should be ≥96%; other highways should be ≥95%. In the construction of expressways and first-class highways, the compaction degree of the partition layer (geomembrane 12 and protective layer 15) should be ≥96%; other highways should be ≥94%. In the construction of expressways and first-class highways, the compaction degree of the partition layer (geomembrane 12 and protective layer 15) to the top of the pavement layer 5 should be ≥94%; other highways should be ≥93%.

As shown in FIG. 2, the present invention provides a saline soil subgrade structure, the saline soil subgrade structure is applied with the above-mentioned saline soil subgrade laying method, and the saline soil subgrade structure includes: a pavement layer 5, The base layer 6, the barrier layer and the road embankment 8; the barrier layer is arranged between the base layer 6 and the road embankment 8; the base layer 6 is arranged between the road surface layer 5 and the barrier layer. The pavement layer 5, the base layer 6 and the embankment 8 are distributed from top to bottom, in which the geomembrane 12 and the protective layer 15 are laid between the base layer 6 and the embankment 8, and the slope of the slope needs to be determined according to the soil quality and the degree of salinization 14.

As an optional embodiment, the loose thickness of the road embankment 8 is less than or equal to 300 mm.

As an optional implementation manner, the slope range of the road arch cross slope 7 of the partition layer is 2%-5%. The slope of the road arch cross slope 7 of the partition layer should not be less than 2%, and the maximum cross slope should not exceed 5%. Slope percentage=elevation increment/horizontal increment (tangent value)*100%, usually expressed as a percentage in engineering.

As an optional embodiment, the blocking layer includes a geomembrane 12 and a protective layer 15 laid on the geomembrane 12 ; the geomembrane 12 is laid on the embankment 8 . The partition layer is set below the base layer 6, higher than 0.5m above the original ground, and not less than the local maximum freezing depth. The geomembrane 12 of the present invention is a water-proof and breathable membrane. The distance between the geomembrane and the foundation is 4 ≥ 0.5m.

As an optional implementation manner, the slope 14 of the road surface layer 5 ranges from 1:1.5 to 1:2. The slope of the slope is also a tangent value, and the unit of elevation is set to 1, that is, slope = slope elevation\horizontal increment, usually expressed as 1:**, for example, 1:1.5 is converted into an angle unit of about 33°

As an optional embodiment, the geomembrane 12 includes an upper layer, an intermediate layer and a lower layer laid in sequence; the upper layer structure is a glass fiber mesh or a loosely treated glass fiber mesh; the intermediate layer is a pore diameter of 0.1-10 μm. Polyethylene waterproof and breathable membrane; the lower layer is a loosely disposed glass fiber mesh. The geomembrane 12 of the present invention is a composite membrane, which can achieve water resistance and ventilation.

The invention solves the disease in the subgrade construction in the saline soil area under the condition that the quality of the sand and gravel material is difficult to control or the groundwater level is high, and improves the economy and safety of the subgrade construction of the saline soil. The water-permeable membrane is used to form the barrier layer. The principle is that the gas in the soil pores, usually in the state of water vapor with a certain humidity, the water particles are very small. According to the principle of capillary motion, it can smoothly penetrate into the capillary to another side, so that the phenomenon of ventilation occurs. When the pores are liquid water, the particles become larger, and due to the surface tension of the water, the water molecules cannot smoothly penetrate to the other side, that is, the penetration of water is prevented, and the breathable membrane has a waterproof function. In specific applications, the material of the waterproof and breathable membrane is selected according to the requirements of aging resistance, corrosion resistance and freezing resistance. It can facilitate the escape of gas in the lower part of the partition layer while the water and salt in the partition soil migrate and rise. It has the characteristics of good water isolation, salt isolation, and simple construction. The lack of trouble and the disadvantage that the traditional geomembrane partition layer is not conducive to the escape of gas in the foundation, so as to better achieve the purpose of treating saline soil foundation diseases.

The barrier layer of the present invention adopts a water-proof and breathable geomembrane. The water-proof and breathable geomembrane is laid according to the width of the roadbed treatment. It should be laid flat and close to the foundation. Geomembrane wraps the area to be treated. The invention can effectively prevent the foundation salt swelling, corrosion and other diseases caused by the migration of water and salt in the saline soil, avoid the accumulation of gas in the soil under the partition layer, and has convenient construction and low construction cost.

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the various embodiments can be referred to each other.

The principles and implementations of the present invention are described herein using specific examples. The descriptions of the above embodiments are only used to help understand the method and the core idea of the present invention; meanwhile, for those skilled in the art, according to the present invention There will be changes in the specific implementation and application scope. In conclusion, the contents of this specification should not be construed as limiting the present invention.

Claims (9)

1. a saline soil roadbed laying method, is characterized in that, comprising: The embankment is obtained by layering compaction and filling from the foundation; laying a barrier layer longitudinally along the route on said embankment; The base layer is backfilled on the barrier layer. 2 . The method for laying saline soil roadbed according to claim 1 , wherein the longitudinally laying a barrier layer along the route on the embankment comprises: 2 . Lay the geomembrane of the barrier layer along the entire section of the road on the embankment; A protective layer of the barrier layer is laid on the geomembrane. 3. The method for laying saline soil roadbed according to claim 2, characterized in that, after laying the protective layer of the barrier layer on the geomembrane, the method further comprises: Coarse-grained soil is laid on the protective layer and rolled; the thickness of the coarse-grained soil and the protective layer is less than or equal to 400mm. 4. A saline soil subgrade structure, wherein the saline soil subgrade structure is applied with the saline soil subgrade laying method according to any one of claims 1-3, and the saline soil subgrade structure comprises: a road surface Layers, base layers, barrier layers and embankments; The blocking layer is arranged between the base layer and the road embankment; the base layer is arranged between the road surface layer and the blocking layer. 5 . The saline soil subgrade structure according to claim 4 , wherein the loose thickness of the embankment is less than or equal to 300 mm. 6 . 6 . The saline soil subgrade structure according to claim 4 , wherein the cross slope of the road arch of the partition layer ranges from 2% to 5%. 7 . 7 . The saline soil roadbed structure according to claim 4 , wherein the blocking layer comprises a geomembrane and a protective layer laid on the geomembrane; the geomembrane is laid on the embankment. 8 . 8 . The saline soil subgrade structure according to claim 4 , wherein the slope of the road surface layer ranges from 1:1.5 to 1:2. 9 . 9 . The saline soil roadbed structure according to claim 7 , wherein the geomembrane comprises an upper layer, a middle layer and a lower layer laid in sequence; the upper layer structure is a glass fiber mesh or a loosely treated glass fiber mesh; the middle The layer is a polyethylene waterproof and breathable membrane with a hole diameter of 0.1-10 μm; the lower layer is a loosely disposed glass fiber mesh.

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