Nanometer bionic hydrophobic partition coarse-particle salinized soil roadbed structure and construction method
By employing a nano-bionic hydrophobic barrier layer structure in saline soil subgrade, the limitations of saline soil subgrade structures in terms of water infiltration and salt migration are solved, achieving high-efficiency stability and durability of saline soil subgrade structures and reducing construction costs.
Patent Information
- Application Number
- CN202511482199.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-16
- Publication Date
- 2025-12-16
AI Technical Summary
Existing saline soil subgrade structures have limitations in blocking water infiltration, preventing water and salt migration, resisting salt corrosion, and maintaining stability. They are also costly to construct and have unsatisfactory results.
The structure employs a nano-bionic hydrophobic barrier layer group, including a first, second, and third barrier layer, which are respectively set between the embankment body and the foundation, between the bottom layer and the surface layer of the subgrade, and on the slope. The barrier layer is formed using nanomaterials such as octadecylamine, sodium methylsilicate, polypropylene fiber, propyltrimethoxysilane, and water. Combined with the drainage ditch design, it blocks the migration of water and salt.
It effectively blocks rainwater infiltration and salt loss, reduces the risk of subsidence and salt swelling, saves on filler transportation costs, reduces environmental pollution, and improves the durability and stability of the roadbed structure.
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Figure CN121138086A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of roadbed structure, in particular to a nano-bionic hydrophobic coarse-grained saline soil roadbed structure and a construction method thereof. BACKGROUND
[0002] In China, silt, silty clay and sandy soil with soluble salt content exceeding 0.3% are defined as saline soil. There are about 1 million km of saline soil in China, nearly 70% of which is distributed in arid regions such as Shaanxi, Gansu, Ningxia, Inner Mongolia, Qinghai and Xinjiang, and the rest is distributed in lake basin and coastal areas in North China Plain. Existing research shows that the soluble salt in saline soil undergoes phase change due to the effects of temperature change, rainfall and evaporation, causing salt heaving and subsidence deformation, which easily causes cracking, uneven settlement and other problems of highway, railway and other structures, seriously affecting the safety and overall traffic capacity of the road. 2
[0003] Existing solutions mainly focus on ground reinforcement, salt reduction and water blocking, but the existing solutions generally have the problems of limited application scenarios, incomplete problem solving, high construction cost and unsatisfactory effect. Therefore, there is an urgent need for a coarse-grained saline soil roadbed structure that can effectively block water infiltration, prevent water and salt migration, resist salt corrosion, has good durability and can maintain its stability for a long time. SUMMARY
[0004] The present application provides a nano-bionic hydrophobic coarse-grained saline soil roadbed structure and a construction method thereof, which aims to improve the durability and stability of the coarse-grained saline soil roadbed structure and reduce the cost of the coarse-grained saline soil roadbed structure.
[0005] In order to achieve the above-mentioned purpose, the present application provides a nano-bionic hydrophobic coarse-grained saline soil roadbed structure, comprising:
[0006] A roadbed body has a slope on both sides along the width direction of the roadbed body, the roadbed body comprises a road embankment body and a base bed bottom layer, and the base bed bottom layer is arranged above the road embankment body;
[0007] A blocking layer group comprises a first blocking layer, a second blocking layer and a third blocking layer, the first blocking layer is arranged between the road embankment body and the foundation, the second blocking layer is arranged on the side of the base bed bottom layer away from the road embankment body, and the third blocking layer is arranged on the slope, the third blocking layer is connected with the first blocking layer and the second blocking layer respectively, so that the blocking layer group surrounds the outer circumferential side of the roadbed body, and the road embankment body and the base bed bottom layer can be filled with coarse-grained saline soil;
[0008] A base bed surface layer is arranged on the side of the second blocking layer away from the base bed bottom layer.
[0009] In an embodiment, the set of partitions comprises a crushed stone cushion disposed between the first partition and the foundation.
[0010] In an embodiment, the set of partitions comprises a geogrid and a medium-coarse sand cushion stacked in sequence, the geogrid is disposed between the medium-coarse sand cushion and the subbase bottom layer, and the medium-coarse sand cushion is disposed between the geogrid and the second partition.
[0011] In an embodiment, the first partition and the second partition are both made of roadbed filler, octadecyl primary amine, sodium methyl silicate, polypropylene fiber, propyl trimethoxysilane and water, the permeability coefficient of the first partition and the second partition is less than 1x10 -9 , the static contact angle of the first partition and the second partition is greater than 150°, and the durability of the first partition and the second partition is greater than 50 years.
[0012] In an embodiment, the third partition is made of nano-silicon dioxide, sodium methyl silicate, propyl trimethoxysilane and water.
[0013] In an embodiment, the roadbed structure further comprises a drainage ditch disposed on opposite sides of the roadbed body along the width direction of the roadbed body, the drainage ditch extends along the extension direction of the roadbed body, and the first partition is connected to the drainage ditch.
[0014] The second aspect of the present application provides a construction method of a nano-bionic hydrophobic partition coarse-grained saline soil roadbed, which is applied to the roadbed structure as described in any one of the preceding embodiments, and the construction method comprises:
[0015] Leveling the foundation and compacting the foundation;
[0016] Laying a first partition above the foundation along the extension direction of the roadbed;
[0017] Laying a roadbed body above the first partition along the extension direction of the roadbed, the roadbed body comprises a roadbed body and a subbase bottom layer, and the subbase bottom layer is disposed above the roadbed body;
[0018] Laying a second partition above the subbase bottom layer along the extension direction of the roadbed;
[0019] Laying a subbase surface layer above the second partition along the extension direction of the roadbed;
[0020] Spray a third partition layer on the side slopes of the embankment body on opposite sides of the embankment body along the width direction of the embankment body, so as to connect the third partition layer with the first partition layer and the second partition layer respectively, so that the embankment body and the subgrade bottom layer can be filled with coarse-grained saline soil.
[0021] In an embodiment, before the step of laying the first partition layer above the foundation along the extension direction of the embankment, the construction method comprises:
[0022] Laying a gravel cushion layer on the foundation along the extension direction of the embankment.
[0023] In an embodiment, before the step of laying the second partition layer above the subgrade bottom layer along the extension direction of the embankment, the construction method comprises:
[0024] Laying a geogrid on the subgrade bottom layer along the extension direction of the embankment.
[0025] Laying a medium-coarse sand cushion layer on the geogrid along the extension direction of the embankment.
[0026] In an embodiment, the construction method further comprises:
[0027] Excavating a drainage ditch on opposite sides of the embankment body along the width direction of the embankment body, and connecting the first partition layer with the drainage ditch.
[0028] The above scheme of the present application has the following advantages:
[0029] In the embodiments of the present application, the first partition layer is arranged between the embankment body and the foundation, the second partition layer is arranged between the subgrade bottom layer and the subgrade surface layer, and the third partition layer is arranged on the side slope and connected with the first partition layer and the second partition layer, so as to isolate the embankment body and the subgrade bottom layer from the external environment. On the one hand, the embankment body and the subgrade bottom layer of the present application can be filled with coarse-grained saline soil in addition to conventional fillers, so that in the process of constructing the embankment structure in a saline soil area, the conventional fillers can be obtained on site, a large amount of transportation cost of the conventional fillers is saved, and there is no need to increase the amount of discarded soil, which is environmentally friendly and pollution-free, and is conducive to reducing the cost of the embankment structure. On the other hand, the path of rainwater penetrating from the side slope of the embankment body into the interior of the embankment body is blocked, the loss of salt in the coarse-grained saline soil is effectively avoided, the possibility of water and soil loss and side slope cracking is reduced, rainwater is prevented from penetrating into the subgrade bottom layer, the embankment body and other lower structures, the dissolution and loss of salt are effectively avoided, the possibility of subsidence of the coarse-grained saline soil embankment structure is reduced, and the tendency of harmful salt in the saline soil foundation migrating to the embankment body is blocked, so that the salt in the embankment body is effectively prevented from accumulating, the harmful salt in the foundation is prevented from eroding the embankment body, and the possibility of salt expansion of the embankment body is reduced.
[0030] Other advantages of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS
[0031] Figure 1 A schematic view of a cross-sectional structure of a roadbed structure in an embodiment of the present application;
[0032] Figure 2 A schematic view of a structure of a gravel cushion layer and a first partition layer in an embodiment of the present application;
[0033] Figure 3 A schematic view of a structure of a geogrid, a medium-coarse sand cushion layer and a second partition layer in an embodiment of the present application;
[0034] Figure 4 A schematic view of a flow of a roadbed construction method in an embodiment of the present application.
[0035] BRIEF DESCRIPTION OF DRAWINGS
[0036] 1, roadbed body; 11, base bed bottom layer; 12, embankment body; 2, first partition layer; 3, second partition layer; 4, third partition layer; 5, base bed surface layer; 6, gravel cushion layer; 7, geogrid; 8, medium-coarse sand cushion layer; 9, drainage ditch; 200, foundation. DETAILED DESCRIPTION
[0037] In order to make the technical problems solved by the present application, the technical solutions and advantages clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are some, but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application. In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as there is no conflict.
[0038] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.
[0039] In the description of the present application, it should be noted that unless otherwise expressly specified and limited, the terms "mounting", "connection", "connecting" should be understood broadly, for example, it can be a locking connection, or a detachable connection, or an integral connection; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or a communication within two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.
[0040] The saline soil roadbed refers to the road base built in the saline soil area, which has special physical and chemical properties. For example, the saline soil railway roadbed is easy to be affected by diseases such as dissolution, salt expansion, and frost heaving, mainly due to the volume change of sulfate salt crystals, the collapse of chloride salt when meeting water, and the gradual destruction of the roadbed structure caused by the upward movement of capillary water and gaseous water carrying salt, which further endangers the safety of driving. In the related art, the solutions mainly focus on three aspects of foundation reinforcement, salt reduction and water blocking:
[0041] 1. Compaction pile method, cylindrical steel pile pipe is punched into the original foundation by impact or vibration method, and pile hole is formed after pulling out. Then the backfilling and tamping of soil, lime soil, lime soil, cement soil and other materials are carried out, so as to form a pile body with increased diameter together with the original foundation to form a composite foundation. The feature is that the original foundation is extruded into a hole without taking soil; when the backfilling material is tamped, the material is further expanded. The composite foundation formed by the compaction pile method can reduce the risk of diseases such as dissolution, salt expansion and frost heaving to a certain extent. However, it is only suitable for crystalline salt content, non-saturated low plasticity saline soil, and cannot block the migration of water and salt from the lower part of the roadbed to the upper part of the roadbed, nor can it block the downward infiltration of water in the upper part of the roadbed, and salt expansion and dissolution may still occur, forming roadbed diseases.
[0042] 2. Dynamic compaction method, the compaction of saline soil within a certain depth of the ground surface is carried out to a dense state by using the compaction energy and shock wave generated by the free fall of a weight of more than 100KN, so as to reduce the voids of the saline soil structure and achieve the purpose of reinforcing the foundation. However, it is only suitable for crystalline salt content, non-saturated low plasticity saline soil, and cannot block the migration of water and salt from the lower part of the roadbed to the upper part of the roadbed, nor can it block the downward infiltration of water in the upper part of the roadbed, and salt expansion and dissolution may still occur, forming roadbed diseases.
[0043] 3. Replacement method, the saline soil within a certain depth is replaced with other coarse particle fillers, so as to achieve the purpose of increasing the stability of the roadbed. However, replacement will generate a large amount of waste soil, and a large amount of high-quality fillers are needed, which greatly increases the cost of fillers and transportation, and the treatment of waste soil will increase the risk of water and soil loss.
[0044] 4. Pre-dissolution by soaking, the saline soil is soaked in water in advance to reduce the salt content. But the pre-dissolution by soaking needs a large amount of water resources, and the saline soil area is mostly water shortage area, and the salt in the lower part of the roadbed can still migrate upward after construction, and salt expansion will still occur when it reaches a certain amount.
[0045] 5. Isolation method, a certain thickness of isolation layer is set at a certain level of roadbed to prevent the upward movement of capillary water and the entry of water and salt into the upper part of the roadbed. The isolation method is currently mainly used for the treatment of saline soil roadbed, and the commonly used isolation layer is a geotextile isolation layer. The geotextile isolation layer is mostly selected as a geomembrane. Since the geomembrane has low strength and is easy to break, and the organic material is easy to age, the current geotextile isolation method can only play a role in the case of protection of the plane layer. The slope and slope protection engineering interfere with each other, the application is difficult, and the durability of the geotextile is insufficient. After the material ages, salt migration problems will still occur.
[0046] 6. Increase the height of the roadbed to reduce the water and salt entering the upper part of the roadbed. However, if the height of the roadbed is not enough, the effect is not good; if it is increased too much, the longitudinal surface will also be adjusted, and the investment will be greatly increased.
[0047] 7. Chemical desalination, chemical treatment is carried out on the saline soil in the upper layer of the roadbed to change the soluble salt components and properties of the saline soil so as to no longer produce salt expansion or reduce salt expansion. However, chemical desalination needs to consume a large amount of chemical desalination raw materials, increases the cost, and the roadbed after desalination still cannot block the upward migration of water salt in the lower stratum.
[0048] Therefore, in view of Figure 1 , the embodiment of the present application provides a kind of nano biomimetic hydrophobic isolation coarse particle saline soil roadbed structure, including roadbed body 1, isolation layer group and base bed surface layer 5.
[0049] The opposite sides of roadbed body 1 along the width direction of itself are provided with slope, to facilitate drainage. Please refer to Figure 1 , the roadbed body 1 includes embankment body 12 and base bed bottom layer 11, and the base bed bottom layer 11 is arranged above the embankment body 12.
[0050] It should be noted that the partition layer group, as a partition structure, can separate the structures or materials on the opposite sides of the partition layer group and cut off the connection or reaction between the structures or materials on the opposite sides. The partition layer group includes a first partition layer 2, a second partition layer 3, and a third partition layer 4. The first partition layer 2 is arranged between the embankment body 12 and the foundation 200 to separate the embankment body 12 and the foundation 200 and cut off the reaction between the embankment body 12 and the foundation 200. The second partition layer 3 is arranged on the side of the subgrade bottom layer 11 away from the embankment body 12 to block the path of rainwater penetrating from above into the subgrade bottom layer 11 and the lower structure such as the embankment body 12. The third partition layer 4 is arranged on the slope, and the third partition layer 4 is connected with the first partition layer 2 and the second partition layer 3 respectively to block the path of rainwater penetrating from the slope of the subgrade body 1 into the inside of the subgrade body 1. The partition layer group is arranged in a manner that the partition layer group surrounds the outer peripheral side of the subgrade body 1 to wrap the subgrade bottom layer 11 and the embankment body 12, so that the subgrade bottom layer 11 and the embankment body 12 can be filled with coarse-grained saline soil.
[0051] It should be noted that the fill of the embankment body 12 generally includes A group soil, B group soil and C group soil, and the fill of the subgrade bottom layer 11 generally includes A group soil and B group soil. The A group soil is high-quality fill, mainly including hard block stone and boulder soil, gravel soil, round gravel soil, angular gravel soil, gravel sand, coarse sand and medium sand with less than 15% fine-grained soil. Such soil has good physical and mechanical properties and stability, and is suitable for key parts and high-demand areas of railway subgrade. The B group soil is good aggregate, including soft block stone which is not easy to weather and various types of soil with poor gradation, but the content of fine-grained soil needs to be between 15% and 30%. In addition, it also includes fine sand, clay sand, sandy clay and the like. The performance of the B group soil is slightly inferior to that of the A group, but it can still meet the filling requirements of most railway subgrades. The C group soil is general fill, mainly including soft block stone which is easy to weather and various types of soil with more than 30% fine-grained soil. In addition, it also includes silt, silt soil and the like. The performance of the C group soil is relatively poor, and it is generally suitable for railway subgrade parts with low filling requirements. Because the salt in saline soil is easy to dissolve in water, rainwater is easy to take away the salt in saline soil after the saline soil is soaked with water, so that the salt in saline soil changes phase under the action of temperature change, rainfall and evaporation, which easily causes salt expansion and subsidence deformation, and easily causes cracking, uneven settlement and other problems of highway, railway and other structures, seriously affecting the safety and overall traffic capacity of the road. Therefore, in actual engineering and specifications, the fill of the subgrade body 1 is not allowed to use coarse-grained saline soil. The subgrade structure of the present application uses the group of partition layers to wrap the embankment body 12 and the subgrade bottom layer 11, so that the embankment body 12 and the subgrade bottom layer 11 are isolated from the foundation 200 and rainwater in the outside world, that is, the embankment body 12 and the subgrade bottom layer 11 are in a relatively independent sealed space under the partition of the group of partition layers, cutting off the connection and reaction of the fill of the embankment body 12 and the subgrade bottom layer 11 with the outside world, so that the embankment body 12 and the subgrade bottom layer 11 of the present application can maintain their bearing capacity even if they are filled with coarse-grained saline soil, and can also avoid subsidence, salt expansion and other diseases of the subgrade structure.
[0052] The subgrade surface layer 5 is arranged on the side of the second partition layer 3 away from the subgrade bottom layer 11, and can form a certain protection for the second partition layer 3.
[0053] In the embodiments of the present application, the first partition layer 2 is arranged between the embankment body 12 and the foundation 200, the second partition layer 3 is arranged between the subgrade bottom layer 11 and the subgrade surface layer 5, and the third partition layer 4 is arranged on the slope and connected with the first partition layer 2 and the second partition layer 3, so as to isolate the embankment body 12 and the subgrade bottom layer 11 from the external environment. On the one hand, the embankment body 12 and the subgrade bottom layer 11 of the present application can be filled with coarse-grained saline soil in addition to the conventional filler, so that the conventional filler can be transported on site in the process of constructing the roadbed structure in the saline soil area, the transportation cost of the conventional filler is greatly saved, and the soil is not discarded, which is environmentally friendly and pollution-free, and is conducive to reducing the cost of the roadbed structure. On the other hand, the path of rainwater penetrating from the slope of the roadbed body 1 into the inside of the roadbed body 1 is blocked, the salt in the coarse-grained saline soil is effectively prevented from flowing away, the possibility of water and soil loss and slope cracking is reduced, the rainwater is prevented from penetrating into the lower structure such as the subgrade bottom layer 11 and the embankment body 12, the dissolution and loss of salt are effectively avoided, the possibility of subsidence of the coarse-grained saline soil roadbed structure is reduced, the harmful salt in the saline soil foundation 200 is prevented from migrating to the embankment body 12, the salt is effectively prevented from gathering in the embankment body 12, the harmful salt in the foundation 200 is prevented from eroding the embankment body 12, and the possibility of salt expansion of the embankment body 12 is reduced.
[0054] In an embodiment, please refer to Figure 2 The partition layer group includes the gravel cushion layer 6, which is arranged between the first partition layer 2 and the foundation 200, that is, the gravel cushion layer 6 is located at the bottom layer of the roadbed structure. On the one hand, the bearing capacity of the gravel cushion layer 6 is strong, which can provide sufficient support force for the roadbed body 1. On the other hand, the gravel cushion layer 6 separates the first partition layer 2 and the foundation 200 to protect the first partition layer 2, and can reduce the capillary water rise height, even eliminate the capillary water rise, and can also remove the water and salt gathered at the bottom of the first partition layer 2 to the opposite sides of the roadbed body 1 along the width direction of the roadbed body 1, so as to reduce the possibility of the harmful salt in the foundation 200 gathering below the embankment body 12.
[0055] In an embodiment, please refer to Figure 3 The partition layer group includes the geogrid 7 and the medium-coarse sand cushion layer 8 stacked in sequence. The geogrid 7 is arranged between the medium-coarse sand cushion layer 8 and the subgrade bottom layer 11 to improve the combination ability between the medium-coarse sand cushion layer 8 and the subgrade bottom layer 11. The medium-coarse sand cushion layer 8 is arranged between the geogrid 7 and the second partition layer 3 to improve the bearing capacity of the roadbed body 1.
[0056] For example, please refer to Figure 3The second partition layer 3 is provided with a medium-coarse sand cushion layer 8 on both sides along the thickness direction of the second partition layer 3. The medium-coarse sand cushion layer 8 located above the second partition layer 3 can guide the water accumulated on the upper part of the second partition layer 3 to the side slopes on both sides to achieve rapid drainage.
[0057] In an embodiment, the materials of the first partition layer 2 and the second partition layer 3 each include sub-base filler, octadecyl primary amine, sodium methyl silicate, polypropylene fiber, propyl trimethoxysilane and water. The permeability coefficients of the first partition layer 2 and the second partition layer 3 are each less than 1 x 10 -9 to present strong hydrophobicity. The static contact angles of the first partition layer 2 and the second partition layer 3 are each greater than 150°. It should be noted that the contact angle refers to the included angle between the tangent of the gas-liquid interface and the solid-liquid interface at the intersection of the three phases of gas, liquid and solid. The size of the contact angle can reflect the interaction strength between the liquid and the solid, and then understand the diffusion, penetration and other behaviors of the liquid on the solid surface. The measurement of the contact angle is usually used to evaluate the wettability of the material. When the contact angle is greater than 90°, the solid surface is hydrophobic, the liquid is not easy to wet the solid, and is easy to move on the surface. The durability of the first partition layer 2 and the second partition layer 3 is greater than 50 years through centrifuge test. For example, the sub-base filler can be a C group filler, and the octadecyl primary amine, the sodium methyl silicate, the polypropylene fiber, the propyl trimethoxysilane and the water are added to the C group filler to form the first partition layer 2 and the second partition layer 3 after mixing. The above-mentioned materials are environmentally friendly and non-polluting, and have good mechanical and durability performance after forming, which is beneficial to guarantee the long-term service and operation safety of the saline soil subgrade.
[0058] In an embodiment, the material of the third partition layer 4 includes nano-silicon dioxide, sodium methyl silicate, propyl trimethoxysilane and water. For example, the hydrophobic modified composite solution is obtained by stirring and mixing the nano-silicon dioxide, the sodium methyl silicate, the propyl trimethoxysilane and the water, and the third partition layer 4 is formed by spraying the hydrophobic modified composite solution on the side slope. The above-mentioned materials are environmentally friendly and non-polluting, and have good mechanical and durability performance after forming, which is beneficial to guarantee the long-term service and operation safety of the saline soil subgrade.
[0059] In an embodiment, please refer to Figure 1The roadbed structure further comprises a drainage ditch 9 arranged on opposite sides of the roadbed body 1 along the width direction of the roadbed body 1, the drainage ditch 9 extending along the extension direction of the roadbed body 1, and the first partition layer 2 is connected with the drainage ditch 9, so that, during rainfall, rainwater can flow along the third partition layer 4 arranged on the slope to the first partition layer 2 and then to the drainage ditch 9 to be quickly drained, which is beneficial to reduce the accumulation of rainwater near the roadbed structure and then the possibility of the rainwater penetrating into the foundation 200 near the roadbed structure, so as to improve the bearing capacity of the saline soil foundation 200.
[0060] Please refer to Figure 4 The second aspect of the embodiment of the present application provides a nano-bionic hydrophobic partition coarse-grained saline soil roadbed construction method, comprising:
[0061] Step S1, leveling the foundation 200 and compacting the foundation 200.
[0062] Exemplarily, temporary drainage should be prepared before the filling construction of the roadbed structure, and the drainage should be introduced and discharged to the ditch outside the roadbed construction range. The field should be cleaned of sundries, weeds, and humus soil, and the field should be leveled. After leveling, the original ground is rolled by a vibrating roller with a rolling capacity not less than 22T according to the requirements of the design document. The rolling quality of the original ground foundation 200 should meet the compaction quality requirements of the corresponding parts.
[0063] Step S2, laying the first partition layer 2 above the foundation 200 along the extension direction of the roadbed.
[0064] Exemplarily, the filler of the first partition layer 2 can be prepared by using A group soil material, B group soil material, or C group soil material. In the process of selecting the filler, the quality should be strictly controlled to ensure that it meets the design requirements. The maximum particle size of the filler should be not greater than 60mm, the content of the particle size less than 0.5mm should be not less than 50%, and the water content should be controlled within ±2% of the optimal water content. The mixing is performed in a premixed manner. 1%~3%octadecyl primary amine, 0.5%~1.5%methyl sodium silicate, 0.5%~1.5%polypropylene fiber (diameter 20µm ~40µm, length 10mm~30mm), 0.5%~1.5%propyl trimethoxysilane, and 10%~30% water are mixed and stirred with C group ordinary filler. During the mixing process, it should be ensured that the various materials are uniformly mixed, and the addition ratio of the filler is automatically controlled to meet the design requirements. The mixing uniformity can be improved by increasing the stirring time and optimizing the stirring equipment, so as to form the first partition layer 2.
[0065] Step S3, laying the roadbed body 1 above the first partition layer 2 along the extension direction of the roadbed, the roadbed body 1 comprising a road embankment body 12 and a bed bottom layer 11, and the bed bottom layer 11 being arranged above the road embankment body 12.
[0066] Exemplarily, the embankment body 12 is provided with a transverse drainage slope of 4% from the center to both sides. If the embankment body 12 is located on a railway platform, a drainage transverse slope of not less than 2% is provided. The embankment body 12 can be selected from A group soil, B group soil or C group soil, or coarse-grained saline soil. The maximum particle size of the filler is not greater than 2 / 3 of the paving thickness, and is not greater than 300 mm. The embankment should be filled in layers and compacted to the specified compaction standard. The base bed bottom layer 11 is provided with a transverse drainage slope of 4% from the center to both sides. If the base bed bottom layer 11 is located on a railway platform, a drainage transverse slope of not less than 2% is provided. The base bed bottom layer 11 can be selected from A group soil or B group soil in gravel, broken stone and sand (except for fine sand), or coarse-grained saline soil. The particle size limit of the filler is ≤200 mm. When the freezing depth is greater than the thickness of the base bed bottom layer 11, the particle size of the A group soil or B group soil in the range of influence of the freezing depth should be less than 0.075 mm, and the content of particles should be not greater than 10%. The base bed bottom layer 11 should be filled in layers and filled to 30 cm below the top surface elevation of the base bed bottom layer 11, and compacted to the specified compaction standard.
[0067] Step S4, a second partition layer 3 is laid above the base bed bottom layer 11 in the extension direction of the roadbed.
[0068] Exemplarily, the filler of the second partition layer 3 can be prepared from A group soil, B group soil or C group soil. In the process of selecting the filler, the quality should be strictly controlled to ensure that it meets the design requirements. The maximum particle size of the filler should be not greater than 60 mm, the content of particles less than 0.5 mm should be not less than 50%, and the water content should be controlled within ±2% of the optimum water content. Mixing is performed in a premixed manner, and 1%~3% octadecyl primary amine, 0.5%~1.5% sodium methyl silicate, 0.5%~1.5% polypropylene fiber (diameter 20µm ~40µm, length 10mm~30mm), 0.5%~1.5% propyl trimethoxysilane, and about 10%~30% water are mixed and stirred with C group ordinary soil. In the mixing process, it should be ensured that the various materials are uniformly mixed, and the addition ratio of the filler is automatically controlled to meet the design requirements. The mixing uniformity can be improved by increasing the stirring time and optimizing the stirring equipment, so as to form the second partition layer 3.
[0069] Step S5, a base bed surface layer 5 is laid above the second partition layer 3 in the extension direction of the roadbed.
[0070] Exemplarily, the filler of the base bed surface layer 5 can be A group soil in gravel and broken stone. The maximum particle size of the filler is ≤100 mm. The filler should have good water permeability, and the permeability coefficient should be greater than 1×10 -5m / s. It should be noted that the base surface layer 5 cannot be saline soil. The maximum particle size of the filler is not greater than 60 mm. The base surface layer 5 should be compacted in layers, and the maximum compacted thickness of each layer should not be greater than 30 cm. The minimum thickness of each layer of the fill should not be less than 10 cm. The roadbed surface of the base surface layer 5 is a triangular camber, and a herringbone drainage slope of not less than 2% is provided from the center to both sides.
[0071] Step S6, spraying the third partition layer 4 on the slopes on both sides of the roadbed body 1 along the width direction of the roadbed body 1, so as to connect the third partition layer 4 with the first partition layer 2 and the second partition layer 3 respectively, so that the roadbed body 12 and the base bottom layer 11 can be filled with coarse-grained saline soil.
[0072] Illustratively, the slopes of the roadbed body 1 are first treated by brushing and slope protection engineering is constructed. After the slope protection engineering is completed, the exposed surface soil of the slope surface is arranged and compacted. After the slope surface is arranged, a hydrophobic modified composite solution is obtained by stirring and mixing 2%-6% nanometer silicon dioxide, 2%-5% methyl sodium silicate, 2%-5% propyl trimethoxysilane and water, and then uniformly sprayed on the roadbed slope. The spraying amount is 1 kg / m 2 ~3 kg / m 2 After natural drying, the third partition layer 4 is formed.
[0073] In the embodiments of the present application, the first partition layer 2, the second partition layer 3 and the third partition layer 4 jointly isolate the roadbed body 1 from the external environment. On the one hand, the roadbed body 12 and the base bottom layer 11 of the present application can use coarse-grained saline soil in addition to conventional fillers for filling, so that in the process of constructing the roadbed structure in the saline soil area, the materials can be taken in situ, saving a large amount of transportation cost of conventional fillers, and without the need to increase the amount of discarded soil, which is environmentally friendly and pollution-free, and is conducive to reducing the cost of the roadbed structure. On the other hand, the path of rainwater penetrating from the slope of the roadbed body 1 into the inside of the roadbed body 1 is blocked, effectively avoiding the loss of salt in the coarse-grained saline soil, reducing the possibility of soil erosion and slope cracking, and preventing rainwater from penetrating into the lower structure such as the base bottom layer 11 and the roadbed body 12, effectively avoiding the dissolution and loss of salt, which is conducive to reducing the possibility of dissolution of the coarse-grained saline soil roadbed structure. The tendency of harmful salt in the saline soil foundation 200 to migrate to the roadbed body 12 is effectively avoided, the salt in the roadbed body 12 is effectively avoided from gathering, the harmful salt of the foundation 200 erodes the roadbed body 12, and the possibility of salt expansion of the roadbed body 12 is reduced.
[0074] In one embodiment, before the first partition layer 2 is laid on the top of the foundation 200 in the extension direction of the roadbed in step S2, the construction method comprises:
[0075] The crushed stone cushion 6 is laid on the foundation 200 along the extension direction of the embankment, on the one hand, the bearing capacity of the crushed stone cushion 6 is strong, which can provide sufficient support force for the embankment body 12; on the other hand, the crushed stone cushion 6 separates the first partition layer 2 and the foundation 200 to protect the first partition layer 2, and the crushed stone cushion 6 can reduce the capillary water rising height, even eliminate the capillary water rising, and can remove the water and salt gathered at the bottom of the first partition layer 2 to the opposite sides of the embankment body 1 along the width direction of the embankment body 1, so as to reduce the possibility of harmful salt in the foundation 200 gathering under the embankment body 12.
[0076] Exemplarily, the crushed stone cushion 6 is laid on the foundation 200 first, and the compacted thickness of the crushed stone cushion 6 is not greater than 0.3 m. After the filling of the first partition layer 2 is transported to the construction site, the bulldozer is used for filling paving, and the loose paving thickness is controlled to be 25 cm. The filling of the first partition layer 2 should be completed within 24 hours after the crushed stone cushion 6 is laid to ensure the good combination between the structure layers. During the filling process of the first partition layer 2, the bulldozer is used for initial leveling, and then the land leveler is used for fine leveling, so as to ensure that the flatness and thickness of each layer are uniform. After fine leveling, the engineering and technical personnel and the survey personnel jointly measure the loose paving top surface elevation at each cross section according to the center line and the left and right boundary lines by using the level, and determine the actual loose paving thickness. Then, the 22T vibrating roller is used for rolling, and the rolling speed of the roller is preferably controlled to be 2 km / h, and is not greater than 3 km / h, so as to ensure the compaction effect and uniformity. The rolling sequence should be according to the operation procedure of first rolling on both sides and then on the middle, first static pressure, then weak vibration, and then strong vibration. First static pressure for 1 time, weak vibration for 3 times, strong vibration for 3 times, and finally static pressure for 1 time to collect light. At the junction of each section, the mutual overlapping compaction should be performed, the longitudinal overlapping length should be not less than 2.0 m, the compaction overlapping along the extension direction of the embankment structure between rows should be not less than 40 cm, and the compaction degree should be not less than 0.92. The compaction thickness of the first partition layer 2 is not less than 20 cm.
[0077] In an embodiment, before the second partition layer 3 is laid on the foundation bed bottom layer 11 along the extension direction of the embankment in step S4, the construction method comprises:
[0078] The geogrid 7 is laid on the foundation bed bottom layer 11 along the extension direction of the embankment to improve the combination ability between the medium-coarse sand cushion 8 and the foundation bed bottom layer 11.
[0079] The medium-coarse sand cushion 8 is laid on the geogrid 7 along the extension direction of the embankment to improve the bearing capacity of the embankment body 1.
[0080] Exemplarily, the geogrid 7 is laid on the base layer 11 first, and then the medium-coarse sand cushion 8 is laid, and the thickness of the medium-coarse sand cushion 8 ranges from 0.05m to 0.1m. After the filler of the second partition layer 3 is transported to the site, the filler is spread by a bulldozer, and the loose thickness is controlled within 25cm. The filling should be completed within 24 hours after the medium-coarse sand cushion 8 is laid to ensure the good combination between the structure layers. First, the bulldozer is used for initial leveling, and then the grader is used for fine leveling to ensure the uniformity of the thickness and the flatness of each layer. After fine leveling, the actual loose thickness is determined by the engineering technicians and surveyors together at each cross section according to the center line and the left and right boundary lines of the design by using the level to measure the loose top surface elevation. Then, the rolling is performed by using a vibrating roller with a rolling speed of not less than 2km / h and not more than 3km / h to ensure the compaction effect and uniformity. The rolling sequence should be performed according to the operation procedure of first static pressure, then weak vibration, and finally strong vibration. The rolling is performed by first static pressure for 1 time, weak vibration for 3 times, strong vibration for 3 times, and finally static pressure for 1 time. At the joint of each section, the compaction should be overlapped, the longitudinal overlapping length should be not less than 2.0m, the compaction overlapping along the longitudinal direction of the road should be not less than 40cm, and the compaction degree should be not less than 0.95. The thickness of the second partition layer 3 is 20cm, and the compaction is completed at one time. Then, a layer of medium-coarse sand cushion 8 is continuously laid on the second partition layer 3, and the thickness of the medium-coarse sand cushion 8 ranges from 0.05m to 0.1m.
[0081] In an embodiment, the construction method further comprises:
[0082] The drainage ditch 9 is excavated on the opposite sides of the road base 1 along the width direction of the road base 1, and the first partition layer 2 is connected with the drainage ditch 9, so that during rainfall, the rainwater can flow along the third partition layer 4 arranged on the slope to the first partition layer 2, and then flow into the drainage ditch 9 to quickly drain the rainwater, which is beneficial to reduce the accumulation of rainwater near the road base structure, and then to reduce the possibility of the rainwater penetrating into the foundation 200 near the road base structure, so as to improve the bearing capacity of the saline soil foundation 200.
[0083] The above describes the preferred embodiments of the present application. It should be noted that those skilled in the art can make some improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.
Claims
1. A nano-bionic hydrophobic barrier structure for coarse-grained saline soil subgrade, characterized in that, include: The roadbed has slopes on both sides along its width direction. The roadbed includes an embankment body and a subgrade layer, with the subgrade layer located above the embankment body. The partition layer group includes a first partition layer, a second partition layer, and a third partition layer. The first partition layer is disposed between the embankment body and the foundation. The second partition layer is disposed on the side of the subgrade layer away from the embankment body. The third partition layer is covered on the slope. The third partition layer is connected to the first partition layer and the second partition layer respectively, so that the partition layer group surrounds the outer periphery of the roadbed body, so that both the embankment body and the subgrade layer can be filled with coarse-grained saline soil. The base bed surface layer is disposed on the side of the second partition layer opposite to the base bed bottom layer.
2. The nano-biomimetic hydrophobic barrier coarse-grained saline soil subgrade structure according to claim 1, characterized in that, The partition layer group includes a crushed stone cushion layer, which is disposed between the first partition layer and the foundation.
3. The nano-biomimetic hydrophobic barrier coarse-grained saline soil subgrade structure according to claim 1, characterized in that, The partition layer group includes geogrid and medium-coarse sand cushion layer stacked in sequence. The geogrid is disposed between the medium-coarse sand cushion layer and the bottom layer of the subgrade, and the medium-coarse sand cushion layer is disposed between the geogrid and the second partition layer.
4. The nano-biomimetic hydrophobic barrier coarse-grained saline soil subgrade structure according to claim 1, characterized in that, Both the first and second partition layers are made of roadbed filler, octadecylamine, sodium methylsilicate, polypropylene fiber, propyltrimethoxysilane, and water. The permeability coefficients of both the first and second partition layers are less than 1 × 10⁻⁶. -9 The static contact angles of both the first and second partition layers are greater than 150°, and the durability of both the first and second partition layers is greater than 50 years.
5. The nano-biomimetic hydrophobic barrier coarse-grained saline soil subgrade structure according to claim 1, characterized in that, The material of the third partition layer includes nano-silica, sodium methylsilicate, propyltrimethoxysilane, and water.
6. The nano-biomimetic hydrophobic barrier coarse-grained saline soil subgrade structure according to claim 1, characterized in that, The roadbed structure also includes drainage ditches, which are disposed on opposite sides of the roadbed body along its width direction and extend along the extension direction of the roadbed body. The first partition layer is connected to the drainage ditch.
7. A method for constructing a nano-bionic hydrophobic barrier coarse-grained saline soil subgrade, characterized in that, The construction method, applied to the roadbed structure as described in any one of claims 1 to 6, comprises: Level the foundation and compact it; A first partition layer is laid on top of the foundation along the extension direction of the roadbed; A roadbed body is laid above the first partition layer along the extension direction of the roadbed. The roadbed body includes an embankment body and a subgrade layer, with the subgrade layer located above the embankment body. A second partition layer is laid above the subgrade layer along the extension direction of the roadbed; A subgrade surface layer is laid above the second partition layer along the extension direction of the roadbed; A third isolation layer is sprayed on the slopes on both sides of the roadbed along its width direction to connect the third isolation layer with the first isolation layer and the second isolation layer respectively, so that both the embankment body and the subgrade bottom layer can be filled with coarse-grained saline soil.
8. The construction method for nano-bionic hydrophobic barrier coarse-grained saline soil subgrade according to claim 7, characterized in that, Before laying the first isolation layer above the foundation along the extension direction of the roadbed, the construction method includes: A crushed stone cushion layer is laid on the foundation along the extension direction of the roadbed.
9. The construction method for nano-bionic hydrophobic barrier coarse-grained saline soil subgrade according to claim 7, characterized in that, Before laying the second partition layer above the subgrade layer along the extension direction of the roadbed, the construction method includes: Geogrids are laid on the subgrade layer along the extension direction of the roadbed; A medium-coarse sand cushion layer is laid on the geogrid along the extension direction of the roadbed.
10. The construction method for nano-bionic hydrophobic barrier coarse-grained saline soil subgrade according to claim 7, characterized in that, The construction method also includes: Drainage ditches are excavated on opposite sides of the road body along its width, and the first partition layer is connected to the drainage ditches.