Expansive soil core-filled roadbed structure

Abstract

The utility model relates to a subgrade structure with an expansive soil filling core. The subgrade structure sequentially comprises a foundation, a broken stone hardcore, a non-woven geotextile inverted filter layer and the expansive soil filling core. The slope surfaces on the two sides of the expansive soil filling core are each sequentially provided with an edge sealing clay layer, a side slope anti-seepage geomembrane and a concrete slope protection building block from inside to outside; an asphalt concrete waterproof layer and a capping clay layer are sequentially arranged at the top of the expansive soil filling core from top to bottom; the top of the expansive soil filling core is provided with a first layer of anti-expansion geocell; a second layer of anti-expansion geocell is arranged below the first layer of anti-expansion geocell in parallel; a permeable hose penetrating into the expansive soil filling core is arranged on the concrete slope protection building block. According to the utility model, the influence on roadbed stability and driving safety caused by embankment slope instability and roadbed surface arching due to water absorption expansion of the expansive soil filling core of the embankment in the plum rain climate region can be avoided, and the long-term stability of the expansive soil filling core embankment in the plum rain climate region is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of railway roadbed engineering, and in particular relates to an expansive soil core-filled embankment structure. Background Art

[0002] Expansive soil is a special soil rich in highly hydrophilic clay minerals and is widely distributed in my country. Expansive soil has the characteristics of swelling, softening, disintegrating, shrinking and cracking when exposed to water. Expansive soil slopes are prone to surface collapse, slope collapse, and slope erosion, affecting the stability of the roadbed. Expansive soil roadbed surfaces are prone to uneven settlement and other diseases, affecting driving safety. However, since there is often a lack of high-quality fillers for roadbed filling in expansive soil areas, if all expansive soil is replaced with non-expansive soil, or if the expansive soil is chemically modified by cement, lime, slag mixtures, etc., it will greatly increase the project cost.

[0003] Continuous rainfall infiltration during the plum rain season is a key factor affecting the performance of expansive soil embankments in plum rain climate zones. In order to effectively utilize the spoil generated by excavation of expansive soil road cuts, when filling the embankment, the expansive soil can be filled in the middle of the embankment, and the outside can be filled with non-permeable fillers such as clay to reduce the permeability of the embankment surface to avoid the core-filled expansive soil absorbing water and swelling, affecting the stability of the roadbed and driving safety.

[0004] At present, relevant literature has proposed a variety of expansive soil core-filled embankment structures. The design of most expansive soil core-filled embankment structures focuses on waterproofing and drainage structures, that is, by setting up drainage systems and waterproof layers to control the water content inside the embankment. However, in actual engineering applications, especially under long-term rainfall conditions in the plum rain climate zone, waterproofing and drainage structures are often insufficient to cope with complex climatic conditions and changeable groundwater environments. It is inevitable that rainwater or groundwater will infiltrate the expansive soil core, and the expansive soil will swell and soften after the water content increases, causing the edge soil to become unstable and collapse, and the roadbed surface to bulge or sink, affecting driving safety. Utility Model Content

[0005] The utility model aims to provide an expansive soil core-filled roadbed structure which can prevent the roadbed slope from becoming unstable and the roadbed surface from arching due to the water swelling of the expansive soil core-filled roadbed in rainy climate zones, which affects the roadbed stability and driving safety.

[0006] The utility model adopts the following technical solutions:

[0007] An expansive soil core-filled roadbed structure comprises a crushed stone cushion layer arranged on a foundation, a non-woven geotextile filter layer arranged on the crushed stone cushion layer, and an expansive soil core-filled layer arranged on the non-woven geotextile filter layer.

[0008] Among them, the slope surfaces on both sides of the expansive soil core are provided with edge-sealing clay layers, slope anti-seepage geomembranes and concrete slope protection blocks in sequence from the inside to the outside; the top of the expansive soil core is provided with an asphalt concrete waterproof layer and a capping clay layer in sequence from top to bottom; the concrete slope protection blocks are supported on the slope foot wall, and the slope foot wall is set on the foundation; the slope foot wall is provided with a slope foot wall drainage hole that penetrates to the gravel cushion layer.

[0009] Among them, a first layer of anti-expansion geocells of the sealing clay layer horizontally penetrating the slopes on both sides is arranged between the top of the expansive soil core and the capping clay layer; a second layer of anti-expansion geocells is arranged parallel to the first layer of anti-expansion geocells; and a permeable hose penetrating into the interior of the expansive soil core is arranged on the concrete slope protection block.

[0010] Among them, a plurality of reinforced geocells are arranged in parallel below the second layer of anti-expansion geocells, and the reinforced geocells are symmetrically arranged on the sealing clay layers of the slopes on both sides and extend into the expansive soil core.

[0011] Wherein, a slope foot wall drainage hole anti-filtration layer is arranged between the slope foot wall drainage hole and the gravel cushion layer.

[0012] Wherein, a drainage ditch is arranged on the outer side of the slope foot wall.

[0013] Wherein, the foundation is provided with a slope inclined from the center of the roadbed to the foot of the slope.

[0014] Wherein, the asphalt concrete waterproof layer forms a triangular road arch.

[0015] Wherein, the first layer of anti-swelling geocell and the second layer of anti-swelling geocell are filled with asphalt mixture.

[0016] Wherein, the reinforced geocell is filled with clay or expansive soil.

[0017] The beneficial effects of the utility model are as follows: the expansive soil core-filled embankment structure of the utility model has a perfect water-proofing, drainage, edge soil reinforcement and roadbed surface anti-expansion structure. The non-woven geotextile anti-filtration layer and the crushed stone cushion layer at its bottom can prevent the migration of moisture to the core-filled expansive soil caused by the rise of the groundwater level or the capillary water action. The edge-sealing clay layer, the capping clay layer, the slope anti-seepage geomembrane and the asphalt concrete waterproof layer can prevent rainfall and slope runoff from infiltrating into the core-filled expansive soil. The anti-expansion geocell can prevent rainfall from infiltrating into the core-filled expansive soil while preventing the expansive soil from absorbing water and expanding and transferring it to the roadbed surface to cause track deformation, thereby ensuring driving safety. The reinforced geocell can prevent the edge-filled clay layer from becoming unstable under the action of the expansive force of the expansive soil.

[0018] The expansive soil core-filled embankment of the utility model has perfect water-isolating and drainage structures, which can prevent external water from infiltrating into the core-filled expansive soil, thereby ensuring the stability of the core-filled expansive soil; the perfect reinforcement and anti-expansion system can ensure the stability of the edge soil and the controllable deformation of the roadbed surface when water infiltrates, thereby ensuring the long-term stable performance of the expansive soil embankment.

[0019] The utility model is conducive to the popularization and application of expansive soil core-filled embankments, fully utilizes the excavated expansive soil, and avoids the adverse effects on the environment caused by soil excavation or chemical improvement of the expansive soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a cross-sectional structural schematic diagram of the utility model.

[0021] Among them, 1 core filling expansive soil, 2 edge sealing clay layer, capping clay layer, 4, crushed stone cushion layer, 5 slope foot wall, 6 non-woven geotextile filter layer, 7 slope anti-seepage geomembrane, 8 concrete slope protection blocks, 9 asphalt concrete waterproof layer, 10 the first layer of anti-expansion geocell, 11 the second layer of anti-expansion geocell, 12 permeable hose, 13 reinforced geocell, 14 drainage ditch, 15 slope foot wall drainage hole, 16 slope foot wall drainage hole filter layer, 17 foundation. DETAILED DESCRIPTION

[0022] The present invention is described in detail and specifically below in conjunction with the accompanying drawings and specific embodiments.

[0023] An expansive soil core-filled roadbed structure comprises a crushed stone cushion layer 4 arranged on a foundation 17 , a non-woven geotextile filter layer 6 arranged on the crushed stone cushion layer 4 , and an expansive soil core-filled 1 arranged on the non-woven geotextile filter layer 6 .

[0024] The core-filled expansive soil 1 is the main part of the expansive soil core-filled embankment, which is wrapped by the clay layer in the center of the embankment. The core-filled expansive soil should be filled with weak expansive soil with a small free expansion rate and expansion force as the filler, which can reduce the risk of deformation and cracking of the embankment. The filling height of the expansive soil shall not exceed 8m, and the slope shall not exceed 1:1.5. The expansive soil shall be filled in layers, and the compaction thickness of each layer shall not exceed 20cm to ensure a good layered compaction effect. During the filling process, the moisture content of the expansive soil should be strictly controlled and kept near the optimal moisture content to ensure the maximum density and stability of the expansive soil.

[0025] The crushed stone cushion layer 4 is located above the foundation, and the foundation is compacted and set with a 2% slope tilted outward. The crushed stone cushion layer uses crushed stones with tough texture, good drainage performance and poor water absorption, and the thinnest filling thickness should not be less than 30cm.

[0026] The non-woven geotextile filter layer 6 is located above the gravel cushion layer 4. The non-woven geotextile filter layer can be made of polyester non-woven geotextile. The polyester material has good filtration performance and can effectively block fine soil while maintaining good water permeability. In addition, the polyester material has excellent durability and anti-aging performance, and is stable under ultraviolet radiation, chemical corrosion and high temperature environments. The tensile strength and puncture resistance of polyester non-woven geotextile are also high, and it can withstand the mechanical stress during the construction process.

[0027] The slopes on both sides of the expansive soil core 1 are provided with edge-sealing clay layers 2, slope anti-seepage geomembranes 7 and concrete slope protection blocks 8 in sequence from inside to outside. The top of the expansive soil core 1 is provided with asphalt concrete waterproof layers 9 and capping clay layers 3 in sequence from top to bottom.

[0028] The edge-sealing clay layer 2 is wrapped around both sides of the core-fill expansive soil 1; the capping clay layer 3 is located on the top of the core-fill expansive soil 1. The edge-sealing clay layer and the capping clay layer should be made of clay with high fine particle content and low water permeability. Its low permeability can effectively prevent water from entering the core-fill expansive soil and reduce the expansion of the expansive soil. Through proper compaction and treatment, low-permeability clay can form a stable edge-sealing layer and provide a long-term stable waterproof barrier. The thickness of the edge-sealing clay layer shall not be less than 1m, and the thickness of the capping clay layer shall not be less than 0.6m.

[0029] The slope anti-seepage geomembrane 7 covers the slope surface of the sealing clay layer 2 on both sides of the embankment and extends to the shoulders on both sides. The slope anti-seepage geomembrane uses a high-density polyethylene (HDPE) anti-seepage membrane. The permeability coefficient of the HDPE anti-seepage membrane is extremely low, and it can provide a reliable anti-seepage effect. The HDPE anti-seepage membrane can adapt to the deformation of expansive soil and is not easily torn. It is particularly suitable for the anti-seepage project of the expansive soil-filled embankment on the slope surface, and can provide sufficient stability and durability in the application. In addition, the HDPE anti-seepage membrane has a strong resistance to erosion of microorganisms and roots, effectively preventing plant roots from penetrating, and ensuring the integrity and durability of the anti-seepage membrane. In terms of environmental protection, the HDPE anti-seepage membrane is non-toxic and harmless, has no negative impact on groundwater and the surrounding ecological environment, and meets the requirements of sustainable development.

[0030] Concrete slope protection blocks 8 are laid on the slope anti-seepage geomembrane 7. Concrete prefabricated blocks with strength grade C30 or above are generally selected. The thickness of the concrete slope protection blocks should be between 10cm and 15cm.

[0031] The asphalt concrete waterproof layer 9 is set on the top of the embankment, with a triangular road arch and a center height of 20 cm (higher than the height of the shoulder point). Before laying the asphalt concrete waterproof layer, the surface of the embankment should be cleaned to ensure that there is no loose material. The construction should adopt hot mixing and hot paving technology to ensure the uniformity and density of the asphalt concrete. When compacting in layers, the thickness of each layer should not exceed 5 cm, and the compaction should meet the design requirements. The joints of the asphalt concrete waterproof layer should be strictly treated with hot-melt joint materials to prevent moisture from penetrating through the joints.

[0032] The concrete slope protection blocks 8 are supported on the slope foot wall 5 ; the slope foot wall 5 is built on the foundation 17 and is provided with a slope foot wall drainage hole 15 connected to the gravel cushion layer 4 .

[0033] The foot wall 5 is arranged at the foot of the slope on both sides of the embankment. The concrete material used for the foot wall can make it have high strength and durability, and can effectively support the concrete slope protection blocks 8. The on-site casting method is adopted for construction. The bottom width of the foot wall is 50cm, the depth of the foundation is 0.8m, and the height above the ground is 0.5m.

[0034] The foot wall is provided with drainage holes 15 at intervals of 5 m in the vertical direction, with a hole diameter of 3 cm, and is horizontally connected to the foot wall 5, with the same height and slope as the foundation; a drainage hole filter layer 16 is provided behind the foot wall. The filter layer is made of geotextile, which has good filtering performance and high water permeability, can effectively intercept fine-grained soil, and allows water to pass through, and is simple to construct, has strong adaptability, good corrosion resistance, and long service life.

[0035] A first layer of anti-expansion geocell 10 of the sealing clay layer 2 horizontally penetrating the slopes on both sides is arranged between the top of the expansive soil core 1 and the capping clay layer 3; a second layer of anti-expansion geocell 11 is arranged parallel to and below the first layer of anti-expansion geocell 10 .

[0036] The first layer of anti-expansion geocell 10 is arranged at the junction of the expansive soil and the clay soil on the upper side of the embankment and is laid horizontally; the second layer of anti-expansion geocell 11 is arranged 0.5m below the first layer of anti-expansion geocell 10 and is laid horizontally. The first layer of anti-expansion geocell 10 and the second layer of anti-expansion geocell 11 are both filled with asphalt mixture.

[0037] The anti-swelling geocell should be made of high-density polyethylene (HDPE). The anti-swelling geocell is filled with asphalt mixture, which has good water-proof properties and can prevent moisture from entering the expansive soil and reduce the expansion phenomenon. At the same time, asphalt mixture has high strength and rigidity. Filling it in the geocell can significantly improve its ability to resist the expansion force of the expansive soil and reduce the deformation of the roadbed surface caused by the deformation of the expansive soil. Asphalt mixture also has good durability and anti-aging properties, and can maintain its physical and mechanical properties for a long time under various climatic conditions.

[0038] A plurality of reinforced geocells 13 are arranged in parallel below the second anti-expansion geocell 11 . The reinforced geocells 13 are symmetrically arranged on the sealing clay layers 2 on both sides of the slope and extend into the expansive soil core 1 .

[0039] The reinforced geocell 13 is located below the second anti-expansion geocell 11, and is arranged vertically at intervals of about 1m, starting from the edge of the sealing clay layer 2 and penetrating 1m of the core filling expansive soil, and laid horizontally. The reinforced geocell 13 is filled with clay soil or expansive soil in the room according to the location of the soil layer.

[0040] The reinforced geocell 13 is also made of high-density polyethylene (HDPE), and is filled with clay or expansive soil. The geocell limits the lateral displacement of expansive soil or clay, increases the shear strength of the soil, and enhances the stability of the embankment slope. In addition, compared with filling asphalt mixture, filling expansive soil or clay is less expensive, which helps to reduce the overall cost of the project, especially in large-scale projects, the economic benefits are more significant. The spacing between the reinforced geocells is 1m.

[0041] The permeable hose 12 is arranged between two reinforced geocells 13, the water outlet height is the same as the reinforced geocell 13, and extends 3 cm out of the concrete slope protection block, penetrates 2 m into the core-filled expansive soil 1, and is inclined outward at a slope of 4%; a permeable hose 12 is arranged every 5 m in the longitudinal direction.

[0042] The diameter of the permeable hose is between 100 and 150 mm, and high-density polyethylene (HDPE) is generally used. HDPE material has good flexibility and can adapt to the deformation of expansive soil when the humidity changes, avoiding hose rupture or failure. The permeable hose has a 4% slope with the horizontal plane, which is convenient for the drainage of water in the embankment. The layout spacing of the permeable hose is determined according to the permeability of the soil and the drainage requirements, and the spacing is between 1 and 2 meters. The layout density should ensure that it can effectively cover the entire embankment area and provide good drainage effect. Wrap geotextile around the permeable hose to prevent fine soil from clogging the hose and ensure long-term drainage effect.

[0043] The drainage ditch 14 is arranged 2m outside the slope foot wall 5 on both sides of the embankment. The base between the drainage ditch 14 and the slope foot wall 5 is compacted and set with a 2% outward slope.

[0044] The drainage ditch is 300mm wide at the bottom, 600mm wide at the top and 400mm deep, and is made of reinforced concrete. Reinforced concrete drainage ditches require less maintenance and are not easily damaged, reducing long-term maintenance costs.

Claims

1. An expansive soil core-filled roadbed structure, characterized in that: It comprises a crushed stone cushion layer (4) arranged on a foundation (17), a non-woven geotextile filter layer (6) arranged on the crushed stone cushion layer (4), and an expanded soil core (1) arranged on the non-woven geotextile filter layer (6); The slope surfaces on both sides of the expansive soil core (1) are provided with edge-sealing clay layers (2), slope anti-seepage geomembranes (7) and concrete slope protection blocks (8) in sequence from the inside to the outside; the top of the expansive soil core (1) is provided with an asphalt concrete waterproof layer (9) and a capping clay layer (3) in sequence from top to bottom; the concrete slope protection blocks (8) are supported on a slope foot wall (5), and the slope foot wall (5) is provided on a foundation (17); the slope foot wall (5) is provided with a slope foot wall drainage hole (15) penetrating to the gravel cushion layer (4); A first layer of anti-expansion geocells (10) of the sealing clay layers (2) horizontally penetrating the slope surfaces on both sides is arranged between the top of the expansive soil core (1) and the capping clay layer (3); a second layer of anti-expansion geocells (11) is arranged in parallel below the first layer of anti-expansion geocells (10); and a water-permeable hose (12) penetrating into the interior of the expansive soil core (1) is arranged on the concrete slope protection block (8).

2. The expansive soil core-filled roadbed structure according to claim 1, characterized in that: A plurality of reinforced geocells (13) are arranged in parallel below the second layer of anti-expansion geocells (11); the reinforced geocells (13) are symmetrically arranged on the edge-sealing clay layers (2) on the slopes on both sides and extend into the expansive soil core (1).

3. The expansive soil core-filled roadbed structure according to claim 1, characterized in that: A slope foot wall drainage hole anti-filter layer (16) is provided between the slope foot wall drainage hole (15) and the crushed stone cushion layer (4).

4. The expansive soil core-filled roadbed structure according to claim 1, characterized in that: A drainage ditch (14) is arranged on the outer side of the slope foot wall (5).

5. The expansive soil core-filled roadbed structure according to claim 1, characterized in that: The foundation (17) is provided with a slope inclined from the center of the roadbed to the foot of the slope.

6. The expansive soil core-filled roadbed structure according to claim 1, characterized in that: The asphalt concrete waterproof layer (9) forms a triangular road arch.

7. The expansive soil core-filled roadbed structure according to claim 1, characterized in that: The first layer of anti-swelling geocells (10) and the second layer of anti-swelling geocells (11) are filled with asphalt mixture.

8. The expansive soil core-filled roadbed structure according to claim 2, characterized in that: The reinforced geocell (13) is filled with clay or expansive soil.

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