CN212357849U - Soil texture improvement roadbed structure of expansive soil in seasonally frozen soil area - Google Patents

Abstract

A soil property improvement roadbed structure of expansive soil in a seasonally frozen soil area sequentially comprises a first improvement enhancement layer, a construction waste filling layer, a second improvement enhancement layer and a construction waste filtering layer from top to bottom, wherein the first improvement enhancement layer and the second improvement enhancement layer have the same components, and the preparation method comprises the following steps: uniformly mixing the steel slag powder and the expansive soil in a mass ratio of 1:4 to form a primary improved expansive soil mixture, crushing the construction waste until the particle size is not more than 10mm, and mixing the construction waste and the primary improved expansive soil mixture in a mass ratio of 2-3:1-2 to form an improved expansive soil filling material; the construction waste filtering layer and the construction waste filling layer are both composed of construction waste with different grain size grading. The utility model discloses utilize building rubbish and slag powder to the native improvement of inflation, not only effectively reduced the water sensitivity of inflation soil, effectively improved the intensity and the freeze-thaw resistance performance of road bed moreover, simultaneously, also make discarded objects such as building rubbish, slag effectively utilize.

Description

Soil texture improvement roadbed structure of expansive soil in seasonally frozen soil area

Technical Field

The utility model relates to road construction field's roadbed structure, specific soil property improvement roadbed structure of soil swelling in seasonally frozen soil area that says so.

Background

The seasonally frozen soil refers to a soil layer frozen in winter and melted in spring. The seasonal frozen soil in China has a wide distribution range, occupies about 53.5 percent of the area of the national soil, and most of the seasonal frozen soil belongs to arid and semiarid water resource shortage areas. The soil layer is affected by temperature, the soil body becomes looser due to the early freeze-thaw deformation, the expansive soil roadbed after freeze-thaw is damaged after being eroded by rainfall, the expansive soil roadbed is easier to erode due to the repeated freeze-thaw action, and the loose soil channel is landslide and eroded under the actions of rainfall and water immersion, so that the engineering quality safety is seriously threatened. The roadbed often has the defects of frost heaving, thawing sinking, strength reduction and the like, and the structural damage and evolution of roadbed fillers are root causes, thereby causing serious economic loss to the infrastructure.

Because the expansive soil contains a large amount of montmorillonite and illite, the water in the soil body is difficult to discharge in the engineering construction process, and the engineering undergoes a repeated freezing and thawing period after completion to generate large frost heaving deformation, thereby seriously threatening the quality and safety of the engineering. The soil layer replacement method adopted by the expansive soil in engineering has the replacement cost of tens of millions per kilometer for widely distributed areas due to the lack of the replacement soil source.

The industrial steel slag and the slag are main waste slag generated in the production of steel products, wherein the discharge amount of the steel slag accounts for a large proportion and approximately accounts for 15-20% of the yield of the steel, and the chemical components of steel slag powder mainly comprise CaO and SiO₂、Fe₂O₃、MgO、MnO₂、Al₂O₃、P₂O₅And the like. The slag is also called slag, is a melt floating on the surface of liquid substances such as metals and the like generated in the pyrometallurgical process, mainly comprises oxides, often contains sulfides and carries a small amount of metals, has huge yield and has low utilization rate of steel slag in China.

With the rapid development of urbanization and construction industry in China, the production quantity of construction waste is over hundred million tons, the total quantity of the construction waste produced in 2013 in China reaches about 10 million tons, the number is increased year by year, and the utilization rate of converting the construction waste into renewable resources is only 5%.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a frozen soil area inflation soil property improvement roadbed structure seasonally, this roadbed structure utilize slag, building rubbish and collapsible loess to improve inflation soil geological conditions, are assisted with special roadbed structure and ventilation drainage structure simultaneously to make precipitation and seasonally freeze the influence and the destruction of road bed and fall to minimumly.

The utility model discloses a realize that the technical scheme that above-mentioned technical purpose adopted does: the utility model provides an inflation soil property improvement roadbed structure in seasonally frozen soil area, this improvement roadbed structure is multilayer composite construction, and has the road bed soil layer of borduring in multilayer composite construction's outside cladding, multilayer composite construction top-down is first improvement enhancement layer, building rubbish filling layer, second improvement enhancement layer and building rubbish reversed filter in proper order, the composition of first improvement enhancement layer and second improvement enhancement layer is the same, and the preparation method is: uniformly mixing the steel slag powder and the expansive soil in a mass ratio of 1:4 to form a primary improved expansive soil mixture, crushing the construction waste until the particle size is not more than 10mm, and mixing the construction waste and the primary improved expansive soil mixture in a mass ratio of 2-3:1-2 to form an improved expansive soil filling material;

the building garbage forming the building garbage filling layer has the particle size not exceeding 100 mm;

the building garbage inverted filter layer is formed by paving broken building garbage serving as a material and is divided into an upper layer, a middle layer and a lower layer from top to bottom, wherein the thickness of the upper layer is 0.5m, and the upper layer is formed by paving large-particle building garbage with the particle size of 35-55 mm; the thickness of the middle layer is 0.3m, and the middle layer is formed by laying medium-particle building garbage with the particle size of 20-40 mm; the thickness of the lower layer is 0.2m, and the lower layer is formed by laying fine-particle building garbage with the particle size not more than 10 mm.

As an optimization scheme of the improved roadbed structure, the section of the improved roadbed structure is in an isosceles trapezoid shape with a narrow top and a wide bottom, L-shaped clamping platforms extending along a roadbed are arranged on two sides of the building rubbish reverse filtering layer and the second improved enhancement layer, the L-shaped clamping platforms are matched with roadbed edge-covering soil layers on the side surfaces to form a containing cavity with a right-angled triangle section, and collapsible loess is filled in the containing cavity;

and vertically drilling a plurality of deep holes downwards on the bottom wall of each cavity along the extending direction of the roadbed until the deep holes reach 0.8-1.5m into an expanded ground surface below the construction waste reverse filter layer, then injecting cement mortar into each deep hole, and forming a seepage anchor column after the cement mortar is solidified, wherein the cement mortar is formed by mixing collapsible loess, coarse sand, cement and water according to the mass ratio of 4:3:1:2, and the uneven coefficient Cu = d60/d10 of the coarse sand is more than or equal to 3.36.

As another optimization scheme of the improved roadbed structure, a plurality of ventilation and drainage mechanisms are distributed in the building rubbish filling layer along the extending direction of the roadbed, each group of ventilation and drainage mechanisms comprises a plurality of groups of ventilation pipe assemblies buried in the building rubbish filling layer along the extending direction of the roadbed, each group of ventilation pipe assembly comprises two inclined pipes and a ventilation main pipe which is positioned at the outer side of the improved roadbed structure and consistent with the extending direction of the roadbed, the two inclined pipes are distributed at two sides in the building rubbish filling layer, adjacent ends of the two inclined pipes are connected into a whole through pipe joints, the free ends of the two inclined pipes respectively extend out of the side edge of the building rubbish filling layer and then are communicated with the atmosphere, a plurality of joints connected with the free ends of the inclined pipes are arranged on the ventilation main pipe, and when ventilation in the inclined pipes is needed, the ventilation main pipe is communicated with the inclined pipes through the joints, a blast pipe connected with a blower is arranged in the middle of the ventilation main pipe; and the upper parts of the two inclined pipes are densely distributed with water permeable holes. The opening of the inclined pipe is in a state of being communicated with the atmosphere, and is used for discharging water in a roadbed, reducing the temperature difference inside and outside the roadbed, reducing uneven settlement, communicating with a connector on a ventilation main pipe when sundries in the pipe need to be cleaned, and further cleaning the sundries by blowing air through an air blower.

As another optimization scheme of the improved roadbed structure, the burying height of the two inclined pipes in the building rubbish filling layer gradually rises from the free end to one end of the pipe joint, and an included angle of 5 degrees is formed between the two inclined pipes and the horizontal plane.

As another optimization scheme of the improved roadbed structure, the distance between two adjacent inclined pipes along the extending direction of the roadbed is 1m, and the ventilation main pipe in each group of ventilation pipe assemblies is connected with 10-20 inclined pipes.

As another optimization scheme of the improved roadbed structure, geotextile is laid between two adjacent layers of the first improved enhancement layer, the construction waste filling layer, the second improved enhancement layer and the construction waste inverted filter layer.

As another optimization scheme of the improved roadbed structure, the thickness of the first improved reinforced layer is 0.8-2.0m, the thickness of the construction waste filling layer is 1.0m, and the thickness of the second improved reinforced layer is 0.8-2.0 m.

The utility model discloses used building rubbish adopts broken abandonment masonry and abandonment concrete.

The utility model discloses the mechanism that utilizes building rubbish, slag and collapsible loess to reform transform inflation dirt road bed lies in:

after the construction waste is mixed with the expansive soil, the water sensitivity of the expansive soil is reduced; the permeability of the expansive soil is increased;

the steel slag contains a large amount of C₂S、C₃S and other active substances which have water hardness gelling property and generate hydration products after hydration, and the steel slag powder is used as a gelling material to be mixed with expansive soil to improve the material, so that the water sensitivity of the expansive soil can be reduced to the maximum extent. The steel slag powder has the characteristics of low temperature resistance and good volume stability, has good freeze-thaw resistance, and can improve the freeze-thaw resistance of seasonal frozen soil by being doped into expansive soil;

collapsible loess has the characteristics of uniform soil quality, loose structure and pore development, and has high strength and low compressibility when not soaked by water. The expansive soil is characterized by being cohesive soil which has the characteristics that the volume is expanded violently after soaking in water and the volume is contracted obviously after dehydration. The expansive soil contains more clay minerals such as montmorillonite and illite, so that the expansive soil has strong hydrophilicity. The utility model discloses utilize collapsible loess, coarse sand and cement and water to mix slip casting formation and stretch into the seepage flow anchor post in the inflation soil, when receiving the rainwash like this, utilize the skeleton effect of coarse sand to produce the seepage flow passageway in the seepage flow anchor post, effectively continuously fill the loess and permeate to the inflation soil in, improve the bad characteristic of inflation soil to solve the crack problem that causes the roadbed after the inflation.

Compared with the prior art, the utility model discloses following beneficial effect has:

1) the utility model utilizes the construction waste and the steel slag powder to improve the expansive soil, thereby not only effectively reducing the water sensitivity of the expansive soil, but also effectively improving the strength and the freeze-thaw resistance of the roadbed, and simultaneously, effectively utilizing the wastes such as the construction waste, the steel slag and the like;

the general construction waste contains a large amount of waste concrete and waste masonry materials, the waste masonry and the concrete have higher hardness and durability, the broken waste bricks and concrete are doped into the expansive soil, the permeability of the expansive soil can be increased, the construction waste and the industrial steel slag are used for treating and improving the expansive soil roadbed, the land occupation and the environmental pollution of the construction waste and the industrial waste stacking are reduced, the road roadbed construction materials are saved, the important significance is realized on promoting the resource utilization of the construction waste and the industrial waste and reducing the engineering disasters of the expansive soil, and considerable social and economic benefits can be brought;

2) the utility model discloses the top level adopts the improvement soil of steel slag powder, building rubbish and expansive soil mixture formation to pave, later reuse level good building rubbish paves the second floor, the third layer reuses the improvement soil pavement the same with the top level, the bottom level adopts the building rubbish of special particle size level to form the inverted filter, this kind of four-layer roadbed structure, not only intensity is high, more importantly, can greatly reduce the water absorption performance of roadbed itself, make the water that permeates into the roadbed get rid of the roadbed as soon as possible, the damage of freeze thawing effect to the roadbed is reduced;

3) the utility model discloses a set up the seepage flow anchor post in the road bed, these seepage flow anchor posts go deep into the inflation soil layer below the road bed, the composition of seepage flow anchor post is that collapsible loess, coarse sand, cement condense and form, wherein cement and coarse sand provide the intensity to support, loess above the seepage flow anchor post slowly permeates the inflation soil along with the rainwater in, improve the inflation soil, fill the crack that the inflation caused, and coarse sand is as the skeleton of seepage flow anchor post and form the seepage flow passageway that supplies loess to erode the flow in the seepage flow anchor post, like this the loess that sets up in the road bed both sides will be sent into constantly to the inflation soil layer and improve;

4) the utility model discloses a building rubbish filling layer, providing great intensity, with the first improvement enhancement layer and the second improvement enhancement layer adjacent from top to bottom, because steel slag powder and swelling soil are filled among them, and the building rubbish particle diameter is also less, therefore its inner gap is far less than building rubbish filling layer, thereby just form twice "water proof wall" at both junctions, the rainwater can be discharged to both sides along the gap of building rubbish filling layer after passing first improvement enhancement layer; in order to further reduce inside deposit water, prevent the destruction of freeze thawing to the road bed structure, the utility model discloses still buried ventilation drainage mechanism in advance in the building rubbish filling layer, ventilation drainage mechanism's main part is the pipeline of a plurality of connections, makes inside and external atmosphere intercommunication of road bed through these pipelines, makes the more quick discharge of water in it, simultaneously, also can utilize the air-blower regularly to carry out the debris clearance to its inside, the maintenance operation of being convenient for.

Drawings

Fig. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is a schematic top view of the vent drain mechanism;

reference numerals: 1. the construction method comprises the following steps of a first improved reinforcing layer, 2 a construction waste filling layer, 3 a second improved reinforcing layer, 4 a construction waste reverse filtering layer, 5 a seepage anchoring column, 6 a roadbed edge-covering soil layer, 7 an L-shaped clamping table, 8 geotextile, 9 a ventilation and drainage mechanism, 901, an inclined pipe, 902 a pipe joint, 903 a ventilation main pipe, 904 a blast pipe, 905 and a water permeable hole.

Detailed Description

The following is to be combined with the specific embodiment to explain the technical scheme of the utility model in further detail, the parts that do not explain in the following embodiments of the utility model all belong to prior art, for example, the method of laying and the road bed method of borduring etc. of each layer that constitutes the roadbed structure.

Example 1

As shown in fig. 1, an expansive soil and soil modified roadbed structure in a seasonally frozen soil area is a multilayer composite structure, a roadbed edge-covering soil layer 6 is coated outside the multilayer composite structure, the multilayer composite structure sequentially comprises a first modified enhancement layer 1, a construction waste filling layer 2, a second modified enhancement layer 3 and a construction waste reverse filter layer 4 from top to bottom, the first modified enhancement layer 1 and the second modified enhancement layer 3 have the same components, and the preparation method comprises the following steps: uniformly mixing the steel slag powder and the expansive soil in a mass ratio of 1:4 to form a primary improved expansive soil mixture, crushing the construction waste until the particle size is not more than 10mm, and mixing the construction waste and the primary improved expansive soil mixture in a mass ratio of 2-3:1-2 to form an improved expansive soil filling material;

the construction waste forming the construction waste filling layer 2 has a particle size not exceeding 100 mm;

the construction waste inverted filter layer 4 is formed by paving broken construction waste serving as a material and is divided into an upper layer, a middle layer and a lower layer from top to bottom, wherein the thickness of the upper layer is 0.5m, and the upper layer is formed by paving large-particle construction waste with the particle size of 35-55 mm; the thickness of the middle layer is 0.3m, and the middle layer is formed by laying medium-particle building garbage with the particle size of 20-40 mm; the thickness of the lower layer is 0.2m, and the lower layer is formed by laying fine-particle building garbage with the particle size not more than 10 mm.

The basic embodiments of the present invention are described above, and further improvements, optimizations and limitations can be made on the above basis, so as to obtain the following embodiments:

example 2

This embodiment is an improved scheme based on embodiment 1, and the main structure thereof is the same as embodiment 1, and the improvement point is that: as shown in fig. 1, the cross section of the improved roadbed structure is an isosceles trapezoid with a narrow upper part and a wide lower part, L-shaped clamping platforms 7 extending along the roadbed are arranged on both sides of the construction waste inverted filter layer 4 and the second improved enhancement layer 3, the L-shaped clamping platforms 7 are matched with roadbed edge-covering soil layers 6 on the side surfaces to form a containing cavity with a right-angled triangle cross section, and collapsible loess is filled in the containing cavity;

and (2) vertically and downwards drilling a plurality of deep holes on the bottom wall of each containing cavity along the extending direction of the roadbed until the deep holes reach 0.8-1.5m into the expanded ground below the construction waste reverse filter layer 4, then injecting cement mortar into each deep hole, and forming a seepage anchor column 5 after the cement mortar is solidified, wherein the cement mortar is formed by mixing collapsible loess, coarse sand, cement and water in a mass ratio of 4:3:1:2, and the uneven coefficient Cu = d60/d10 of the coarse sand is more than or equal to 3.36.

Example 3

The present embodiment is an improved scheme based on embodiment 2, and the main structure of the present embodiment is the same as that of embodiment 2, and the improvement point is that: as shown in fig. 1 and 2, a plurality of ventilation and drainage mechanisms 9 are distributed in the construction waste filling layer 2 along the extending direction of the roadbed, each group of ventilation and drainage mechanisms 9 comprises a plurality of groups of ventilation pipe assemblies embedded in the construction waste filling layer 2 along the extending direction of the roadbed, each group of ventilation pipe assembly comprises two inclined pipes 901 and a ventilation main pipe 903 which is positioned outside the improved roadbed structure and is consistent with the extending direction of the roadbed, the two inclined pipes 901 are distributed at two sides in the construction waste filling layer 2, adjacent ends of the two inclined pipes are connected into a whole through pipe joints 902, the free ends of the two inclined pipes 901 respectively extend out of the side edge of the construction waste filling layer 2 and then are communicated with the atmosphere, the ventilation main pipe 903 is provided with a plurality of joints connected with the free ends of the inclined pipes 901, when ventilation in the inclined pipes 901 is needed, the ventilation main pipe 903 is communicated with the inclined pipes 901 through the joints, a blast pipe 904 connected with a blower is arranged in the middle of the ventilation main pipe 903; the upper half parts of the two inclined pipes 901 are densely distributed with water permeable holes 905.

In this embodiment, the opening of the inclined pipe 901 is in a state of being communicated with the atmosphere for discharging water in the roadbed, reducing the temperature difference between the inside and the outside of the roadbed, thereby reducing uneven settlement, and when the sundries in the pipe need to be cleaned, the pipe joint is communicated with the air blower, and air is blown in to clean the sundries.

Of course, this embodiment may also be modified based on embodiment 1, and the modification point is the same as that of embodiment 2.

Example 4

This embodiment is an improved scheme based on embodiment 3, and the main structure thereof is the same as embodiment 3, and the improvement point is that: as shown in fig. 1, the two inclined pipes 901 are gradually raised from the free ends to the end of the pipe joint 902 at the burying height in the construction waste filling layer 2, and form an angle of 5 ° with the horizontal plane.

Of course, this embodiment can also be improved on the basis of embodiment 3, and the improvement contents are consistent.

The upper half part of the inclined pipe 901 in this embodiment means that the inclined pipe 901 is divided into two halves in the diameter direction, permeable holes 905 are densely distributed on the surface of one half, and when embedding, one side on which the permeable holes 905 are distributed is arranged on the upper side, and the other side is arranged on the lower side; the inclined pipe 901, the ventilation main pipe 903 and the blast pipe 904 are all made of PVC pipes, the diameter of the inclined pipe 901 is 5cm, and the diameters of the ventilation main pipe 903 and the blast pipe 904 are 10 cm.

Example 5

This embodiment is another modified scheme based on embodiment 4, and the main structure thereof is the same as embodiment 4, and the improvement point is that: as shown in FIG. 2, the distance between two adjacent inclined tubes 901 is 1m along the extension direction of the road base, and the vent main pipe 903 in each vent pipe assembly is connected with 10-20 inclined tubes 901.

Of course, this embodiment can also be improved on the basis of embodiment 3, and the improvement contents are consistent.

Example 6

The present embodiment is another modified scheme based on embodiment 1, and the main structure of the present embodiment is the same as that of embodiment 1, and the improvement point is that: as shown in fig. 1, geotextile 8 is laid between two adjacent layers of the first improved reinforcing layer 1, the construction waste filling layer 2, the second improved reinforcing layer 3 and the construction waste inverted filter layer 4.

Example 7

The present embodiment is another modified scheme based on embodiment 1, and the main structure of the present embodiment is the same as that of embodiment 1, and the improvement point is that: as shown in fig. 1, the thickness of the first improved reinforcing layer 1 is 0.8-2.0m, the thickness of the construction waste filling layer 2 is 1.0m, and the thickness of the second improved reinforcing layer 3 is 0.8-2.0 m.

Claims (7)

1. The utility model provides a soil property improvement roadbed structure of seasonally frozen soil area inflation, this improvement roadbed structure be multilayer composite construction, and has the road bed soil layer (6) of borduring in multilayer composite construction's outside cladding, multilayer composite construction top-down is first improvement enhancement layer (1), building rubbish filling layer (2), second improvement enhancement layer (3) and building rubbish reversed filter (4) in proper order, its characterized in that: the first improved enhancement layer (1) and the second improved enhancement layer (3) have the same components, and the preparation method comprises the following steps: uniformly mixing the steel slag powder and the expansive soil in a mass ratio of 1:4 to form a primary improved expansive soil mixture, crushing the construction waste until the particle size is not more than 10mm, and mixing the construction waste and the primary improved expansive soil mixture in a mass ratio of 2-3:1-2 to form an improved expansive soil filling material;

the construction waste forming the construction waste filling layer (2) has the particle size not exceeding 100 mm;

the construction waste inverted filter layer (4) is formed by paving broken construction waste serving as a material and is divided into an upper layer, a middle layer and a lower layer from top to bottom, wherein the thickness of the upper layer is 0.5m, and the upper layer is formed by paving large-particle construction waste with the particle size of 35-55 mm; the thickness of the middle layer is 0.3m, and the middle layer is formed by laying medium-particle building garbage with the particle size of 20-40 mm; the thickness of the lower layer is 0.2m, and the lower layer is formed by laying fine-particle building garbage with the particle size not more than 10 mm.

2. The improved roadbed structure of the expansive soil in the seasonally frozen soil region, according to claim 1, is characterized in that: the section of the improved roadbed structure is an isosceles trapezoid with a narrow upper part and a wide lower part, L-shaped clamping platforms (7) extending along a roadbed are arranged on two sides of the building rubbish reverse filtering layer (4) and the second improved enhancement layer (3), the L-shaped clamping platforms (7) are matched with roadbed edge-covering soil layers (6) on the side surfaces to form a containing cavity with a right-angled triangle section, and collapsible loess is filled in the containing cavity;

and (2) vertically and downwards drilling a plurality of deep holes on the bottom wall of each containing cavity along the extending direction of the roadbed until the deep holes reach 0.8-1.5m into an expansion ground surface below the construction waste reverse filter layer (4), then injecting cement mortar into each deep hole, and forming a seepage anchor column (5) after the cement mortar is solidified, wherein the cement mortar is formed by mixing collapsible loess, coarse sand, cement and water according to the mass ratio of 4:3:1:2, and the uneven coefficient Cu = d60/d10 of the coarse sand is more than or equal to 3.36.

3. The expansive soil texture improved roadbed structure in the seasonally frozen soil area, according to claim 1 or 2, is characterized in that: a plurality of ventilation and drainage mechanisms (9) are distributed in the building waste filling layer (2) along the extending direction of the roadbed, each ventilation and drainage mechanism (9) comprises a plurality of groups of ventilation pipe assemblies which are embedded in the building waste filling layer (2) along the extending direction of the roadbed, each group of ventilation pipe assembly comprises two inclined pipes (901) and a ventilation main pipe (903) which is positioned at the outer side of the improved roadbed structure and is consistent with the extending direction of the roadbed, the two inclined pipes (901) are distributed at two sides in the building waste filling layer (2), the adjacent ends are connected into a whole through pipe joints (902), the free ends of the two inclined pipes (901) respectively extend out of the side edge of the building waste filling layer (2) and are communicated with the atmosphere, the ventilation main pipe (903) is provided with a plurality of joints which are connected with the free ends of the inclined pipes (901), when the inclined pipes (901) are required to be ventilated, the ventilation main pipe (903) is communicated with a plurality of inclined pipes (901) through the joints, and a blast pipe (904) connected with a blower is arranged in the middle of the ventilation main pipe (903); the upper parts of the two inclined pipes (901) are densely distributed with water permeable holes (905).

4. The improved roadbed structure of the expansive soil in the seasonally frozen soil region, according to claim 3, is characterized in that: the embedding height of the two inclined pipes (901) in the building garbage filling layer (2) gradually rises from the free ends to one end of the pipe joint (902), and an included angle of 5 degrees is formed between the two inclined pipes and the horizontal plane.

5. The expansive soil texture improved roadbed structure in the seasonally frozen soil area, according to the claim 4, is characterized in that: and the distance between two adjacent inclined pipes (901) is 1m along the extension direction of the roadbed, and the ventilation main pipe (903) in each group of ventilation pipe assemblies is connected with 10-20 inclined pipes (901).

6. The improved roadbed structure of the expansive soil in the seasonally frozen soil region, according to claim 1, is characterized in that: and geotextile (8) is laid between the adjacent two layers in the first improved enhancement layer (1), the construction waste filling layer (2), the second improved enhancement layer (3) and the construction waste reverse filtering layer (4).

7. The improved roadbed structure of the expansive soil in the seasonally frozen soil region, according to claim 1, is characterized in that: the thickness of the first improved reinforcing layer (1) is 0.8-2.0m, the thickness of the construction waste filling layer (2) is 1.0m, and the thickness of the second improved reinforcing layer (3) is 0.8-2.0 m.

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