Roadbed structure for comprehensively utilizing bulk salinized soil and construction method thereof

Abstract

The invention discloses a roadbed structure capable of comprehensively utilizing bulk salinized soil and a construction method of the roadbed structure, solves the problem that a salinized soil roadbed structure in the prior art is complex and inconvenient to construct, and has the beneficial effects that material sources are convenient to obtain, and construction is convenient. Comprising a modified salinized soil filling roadbed, the section of the modified salinized soil filling roadbed is in a trapezoid shape with the narrow upper portion and the wide lower portion, a partition layer is laid in the modified salinized soil filling roadbed and is made of salinized soil base foam light soil, and the height between the partition layer and the top of the modified salinized soil filling roadbed is smaller than the height between the partition layer and the bottom of the modified salinized soil filling roadbed. The modified salinized soil filler roadbed is prepared from salinized soil, limestone powder and gypsum, and the salinized soil based foam light soil is prepared from salinized soil, cement, a foaming agent and water.

Description

Technical Field

[0001] The invention relates to the field of roadbed structures, in particular to a roadbed structure for comprehensive utilization of bulk saline soil and a construction method thereof. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Saline soil is a special soil with a salt content greater than 0.5%, which has special engineering characteristics such as salt swelling, dissolution and corrosion. Common saline soils can be mainly divided into sulfate saline soil, chloride saline soil and carbonate saline soil according to the types of soluble salts they contain. Saline soil is not only widely distributed, but also has a series of special physical, chemical and engineering properties. These properties make the roadbed engineering construction and long-term performance assurance in saline soil areas face many challenges. Among them, the expansion of saline soil is particularly prominent. When saline soil absorbs water, the distance between soil particles will change due to the effect of salt, resulting in significant volume expansion. This expansion phenomenon often causes uneven deformation and even cracking of the roadbed. This deformation not only seriously affects the flatness of the road surface, brings many inconveniences to driving, but also poses a potential threat to driving safety. In the long run, highway projects in saline soil areas often face more serious maintenance and repair problems.

[0004] In recent years, the number and scale of highway projects in saline soil areas have continued to increase. However, due to the special properties of saline soil, these highway projects face many technical difficulties during construction and use. How to choose suitable roadbed modification materials and how to design a reasonable roadbed barrier structure are issues that need to be solved urgently. These issues are not only related to the construction quality and service life of highway projects, but also to the development of local economy and society.

[0005] Chinese patent application CN201710013851.3, entitled "A saline soil roadbed filler and a method for improving the roadbed", was published on May 24, 2017. It uses soluble calcium salts, urea and microbial agents to make the saline soil roadbed filler have higher compressive strength.

[0006] Chinese patent application CN202010079233.0, entitled "A device and construction method for saline soil roadbed in seasonally frozen soil areas", was published on May 5, 2020. The roadbed is equipped with earth roadbed, heat stabilization measures, isolation measures, etc., which can maintain the long-term stability of water, heat and salt in the roadbed.

[0007] The inventors found that the soluble calcium salts, urea and microbial agents used in the above-mentioned roadbed structure in the process of modifying saline soil are not stable enough in the actual construction process, resulting in the inability to ensure the stability of the saline soil roadbed; other heat stabilization measures, isolation measures, etc. make the roadbed structure complicated and inconvenient for construction; geomembranes are also used for isolation in the prior art. Although the geomembrane isolation layer has good water and salt isolation and simple construction characteristics, under the action of complex soil and water potential, water and salt are easily accumulated under the membrane, which can easily soften the soil layer under the membrane, causing new salt swelling and uneven deformation and other diseases.

[0008] In addition, the structural strength of the saline soil roadbed modified with soluble calcium salts, urea and microbial agents is not effectively guaranteed and is not suitable for roadbeds with heavy loads. Summary of the invention

[0009] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a roadbed structure for comprehensive utilization of bulk saline soil, rationally utilize a large amount of saline soil along the highway, and ensure the long-term and short-term service performance of the roadbed.

[0010] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0011] A roadbed structure for comprehensive utilization of bulk saline soil, including a modified saline soil filling roadbed, the cross-section of the modified saline soil filling roadbed is a trapezoid that is narrow at the top and wide at the bottom, a partition layer is laid in the modified saline soil filling roadbed, the partition layer adopts saline soil-based foamed lightweight soil, the height between the partition layer and the top of the modified saline soil filling roadbed is less than the height between the partition layer and the bottom of the modified saline soil filling roadbed, the modified saline soil filling roadbed consists of saline soil, limestone powder and gypsum, and the saline soil-based foamed lightweight soil consists of saline soil, cement, foaming agent and water.

[0012] In the roadbed structure for comprehensive utilization of bulk saline soil as described above, the thickness of the barrier layer is 0.25-0.4 m, and the barrier layer and the top plane of the modified saline soil filling roadbed are arranged parallel to each other.

[0013] In the roadbed structure for comprehensive utilization of bulk saline soil as described above, the height between the barrier layer and the top of the modified saline soil filling roadbed is 0.8-1.2 m.

[0014] In the roadbed structure for comprehensive utilization of bulk saline soil as described above, the length of the barrier layer is less than or equal to the length of the modified saline soil filling roadbed where it is located, and the width of the barrier layer is less than or equal to the width of the transverse section of the modified saline soil filling roadbed where it is located.

[0015] As described above, in a roadbed structure for comprehensive utilization of bulk saline soil, the compositions of saline soil, limestone powder and gypsum in the modified saline soil filling roadbed are 60%-75%, 15%-26% and 10%-18%, respectively, which effectively controls the pH value and salt content of the saline soil and improves the soil structure.

[0016] As described above, a roadbed structure for comprehensive utilization of bulk saline soil, wherein the components of saline soil, cement, foaming agent and water in the saline soil-based foamed lightweight soil are 30%-40%, 26%-35%, 6%-10% and 25%-35%, forming a saline soil-based foamed lightweight soil with a certain compressive strength, thereby ensuring the structural strength of the modified saline soil filling roadbed.

[0017] As described above, a roadbed structure for comprehensive utilization of bulk saline soil, in another scheme, in order to enhance the strength of the modified saline soil filling roadbed, a geocell is laid in the modified saline soil filling roadbed, and the geocell is filled with the saline soil-based foam lightweight soil. The geocell has a reinforcement effect, further improving the roadbed stiffness and strength, and the geocell is filled with saline soil-based foam lightweight soil to ensure the strength of the geocell, and is bonded to the saline soil-based foam lightweight soil on the upper and lower sides of the geocell.

[0018] In the roadbed structure for comprehensive utilization of bulk saline soil as described above, the geocells are arranged in multiple layers along the height direction of the modified saline soil filling roadbed, wherein one layer of geocells is arranged on the upper side of the partition layer, and at least one layer of geocells is arranged on the lower side of the partition layer.

[0019] As described above, in a roadbed structure for comprehensive utilization of bulk saline soil, a roadbed is arranged on the inner side of the modified saline soil filling roadbed, the bottom of the roadbed is flush with the top of the barrier layer, the top of the roadbed is flush with the top of the modified saline soil filling roadbed, and ordinary fillers are filled in the roadbed.

[0020] In a second aspect, the present invention also provides a construction method for a roadbed structure for comprehensive utilization of bulk saline soil, comprising the following contents:

[0021] The saline soil is modified by limestone powder and gypsum to obtain the material used for the modified saline soil filling roadbed;

[0022] From bottom to top, the modified saline soil filler roadbed is constructed in layers, and compacted after the layered construction;

[0023] When the modified saline soil filler roadbed is constructed to the set height, the barrier layer is laid. During the construction of the barrier layer, the saline soil, cement, foaming agent and water are mixed to form saline soil base foam lightweight soil;

[0024] After the construction of the barrier layer is completed, the modified saline soil filler roadbed is constructed on the top of the barrier layer.

[0025] The beneficial effects of the present invention are as follows:

[0026] 1) The present invention adopts a modified saline soil filling roadbed and a saline soil base foam lightweight soil to set a partition layer, and the two are combined to make comprehensive use of bulk saline soil, with double protection, to form a new type of saline soil roadbed structure, and to ensure the long-term operation of the saline soil roadbed; the components of the modified saline soil filling roadbed are saline soil, limestone powder and gypsum, and the components of the saline soil base foam lightweight soil are saline soil, cement, foaming agent and water. The raw materials used are all easily available materials, which is conducive to the rapid acquisition of materials and convenient construction.

[0027] 2) The components of the saline soil-based foamed lightweight soil in the present invention are saline soil, cement, foaming agent and water. Salt water migrates with the migration of water. Cement is used in the saline soil-based foamed lightweight soil, which has strong water absorption and water retention properties, resulting in the moisture content in the upper part of the barrier layer being less than the initial moisture content, having a good barrier effect on moisture, and effectively preventing the salt below the barrier layer from invading the roadbed structure, thereby ensuring the barrier effect; because there is water in the components, moisture is a good thermal conductive medium, and the pore structure of the foamed lightweight soil during the molding process can limit the penetration and conduction of moisture, thereby reducing the presence of moisture and reducing the thermal conductivity. The thermal conductivity of the foamed lightweight soil decreases with the increase of porosity. The higher the porosity, the more uniform and unconnected the pore structure is, and the lower the thermal conductivity is, so that the saline soil-based foamed lightweight soil has good thermal insulation properties, thereby improving the durability of the roadbed in cold and arid areas.

[0028] 3) The thickness of the partition layer in the present invention is set appropriately, neither too thick nor too thin, and while ensuring the thermal insulation performance of the partition layer, it is convenient for construction and controls costs.

[0029] 4) In the present invention, geocells are laid in the modified saline soil filler roadbed. The geocells have a reinforcement effect, which further improves the stiffness and strength of the roadbed. The geocells are filled with saline soil-based foamed lightweight soil to ensure the strength of the geocells and are bonded together with the saline soil-based foamed lightweight soil on the upper and lower sides of the geocells. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0031] Figure 1 It is a schematic diagram of a roadbed structure for comprehensive utilization of bulk saline soil in the first embodiment of the present invention.

[0032] Figure 2It is a schematic diagram of a roadbed structure for comprehensive utilization of bulk saline soil in the second embodiment of the present invention.

[0033] Figure 3 It is a schematic diagram of a roadbed structure for comprehensive utilization of bulk saline soil in the second embodiment of the present invention.

[0034] In the figure: the distances or sizes between parts are exaggerated to show the positions of various parts, and the schematic diagram is for reference only.

[0035] Among them: 1. Modified saline soil filling roadbed, 2. Roadbed, 3. Isolation layer, 4. Geocell, 5. Oblique isolation layer. DETAILED DESCRIPTION

[0036] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0037] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless otherwise explicitly stated in the present invention, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "include" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof;

[0038] As introduced in the background technology, the existing saline soil roadbed structure is complex and inconvenient to construct, and the material source is easy to obtain and convenient to construct. In order to solve the above technical problems, the present invention proposes a roadbed structure for comprehensive utilization of bulk saline soil.

[0039] Embodiment 1

[0040] In a typical embodiment of the present invention, reference is made to Figure 1 As shown, a roadbed structure for comprehensive utilization of bulk saline soil includes a modified saline soil filling roadbed 1. The cross-section of the modified saline soil filling roadbed 1 is a trapezoid that is narrow at the top and wide at the bottom, specifically an isosceles trapezoid, with the top arranged horizontally. A barrier layer 3 is laid in the modified saline soil filling roadbed. The barrier layer 3 adopts saline soil-based foamed lightweight soil. The height between the barrier layer 3 and the top of the modified saline soil filling roadbed 1 is less than the height between the barrier layer and the bottom of the modified saline soil filling roadbed. The components of the modified saline soil filling roadbed are saline soil, limestone powder and gypsum, and the components of the saline soil-based foamed lightweight soil are saline soil, cement, foaming agent and water.

[0041] It is easy to understand that the longitudinal cross-section of the partition layer can be rectangular, and the partition layer 3 is arranged horizontally. Of course, in other examples, the partition layer can also be arranged inclined.

[0042] In this embodiment, the thickness of the barrier layer is 0.25-0.4m, preferably 0.3m. The barrier layer and the top plane of the modified saline soil filling roadbed are arranged parallel to each other. The height between the barrier layer and the top of the modified saline soil filling roadbed is 0.8-1.2m to ensure the thickness of the roadbed.

[0043] It is easy to understand that in order to effectively ensure the barrier effect and prevent the salt below from invading the roadbed structure, the length of the barrier layer is less than or equal to the length of the modified saline soil filling roadbed where it is located, and the width of the barrier layer is less than or equal to the width of the transverse section of the modified saline soil filling roadbed where it is located. Because the modified saline soil filling roadbed is trapezoidal, the two ends of the top of the barrier layer are located on the slope of the modified saline soil filling roadbed.

[0044] Specifically, the components of saline soil, limestone powder and gypsum in the modified saline soil filling roadbed are 60%-75%, 15%-26% and 10%-18%, among which the main component of lime powder is calcium carbonate, and the main component of gypsum is calcium sulfate. The saline soil is alkaline, and the alkalinity of the saline soil is neutralized by acidic lime powder and gypsum, which effectively controls the pH value of the saline soil. In addition, sulfate ions SO4 in the saline soil 2- With calcium ions Ca in lime powder and gypsum 2+ The plate-like composite crystal salt dihydrate calcium sulfate crystals generated by the reaction can effectively reduce the free sulfate content in saline soil, reduce salt expansion deformation, effectively reduce the salt content of saline soil, and improve soil structure.

[0045] In this embodiment, the components of saline soil, cement, foaming agent and water in the saline soil-based foamed lightweight soil are 30%-40%, 26%-35%, 6%-10% and 25%-35%, forming a saline soil-based foamed lightweight soil with a certain compressive strength to ensure the structural strength of the isolation layer; the saline soil-based foamed lightweight soil contains cement, and the cement particle size is smaller than the soil particles. The small particles can fill the pores of the saline soil, so that the soil particles in the saline soil-based foamed lightweight soil are more evenly distributed; the salt water migrates with the migration of water, and the saline soil-based foamed lightweight soil contains cement, which has strong water absorption and water retention, so As a result, the moisture content in the upper part of the barrier layer is also lower than the initial moisture content, which has a good barrier effect on moisture and effectively prevents the salt below the barrier layer from invading the roadbed structure; because there is water in the composition, moisture is a good thermal conductive medium, and the pore structure of the foam lightweight soil during the molding process can limit the penetration and conduction of moisture, thereby reducing the presence of moisture and reducing the thermal conductivity. The thermal conductivity of the foam lightweight soil decreases with the increase of porosity. The higher the porosity, the more uniform the pore structure and the lower the thermal conductivity, which makes the saline soil-based foam lightweight soil have good thermal insulation performance and improves the durability of the roadbed in cold and arid areas;

[0046] Specifically, the foaming agent can be selected from existing spherical EPS polystyrene foam.

[0047] It is easy to understand that a roadbed is set inside the modified saline soil filling roadbed, the bottom of the roadbed is flush with the top of the barrier layer, the top of the roadbed is flush with the top of the modified saline soil filling roadbed, and the roadbed is filled with ordinary filler, which can be backfill soil.

[0048] The roadbed structure provided by the present invention adopts a modified saline soil filling roadbed and a saline soil base foam lightweight soil to set a partition layer, and the two are combined to carry out comprehensive utilization of bulk saline soil, double protection, create a new type of saline soil roadbed structure, and ensure the long-term operation of the saline soil roadbed; the components of the modified saline soil filling roadbed are saline soil, limestone powder and gypsum, and the components of the saline soil base foam lightweight soil are saline soil, cement, foaming agent and water. The raw materials used are all easily available materials, which is conducive to the rapid acquisition of materials and convenient construction.

[0049] Embodiment 2

[0050] The difference between this embodiment and the first embodiment is that:

[0051] In order to enhance the strength of the modified saline soil filling roadbed, a geocell is laid in the modified saline soil filling roadbed. Figure 2As shown, the geocell 4 is filled with saline soil-based foam lightweight soil, and the geocell 4 has a reinforcement effect, which further improves the stiffness and strength of the roadbed. The geocell 4 is filled with saline soil-based foam lightweight soil to ensure the strength of the geocell and bonded with the saline soil-based foam lightweight soil on the upper and lower sides of the geocell. This enhances the strength of the entire modified saline soil filling roadbed, and can be used in roadbeds with larger bearing loads.

[0052] Along the height direction of the modified saline soil filling roadbed, multiple layers of geocells are arranged, wherein one layer of geocells is arranged on the upper side of the partition layer, and at least one layer of geocells is arranged on the lower side of the partition layer. For example, two layers of geocells can be arranged on the lower side of the partition layer. During the layered construction of the modified saline soil filling roadbed, the geocells are laid.

[0053] It is easy to understand that the length of the geocell is the same as the length of the modified saline soil filling roadbed, and the width can be less than or equal to the width of the modified saline soil filling roadbed where it is located.

[0054] Embodiment 3

[0055] The difference between this embodiment and the first or second embodiment is that:

[0056] refer to Figure 3 As shown, an oblique barrier layer 5 is also laid on the inner side of the modified saline soil filling roadbed, and the modified saline soil filling roadbed is separated from the roadbed 2 by the oblique barrier layer 5 to prevent salt from invading the roadbed. The oblique barrier layer 5 is arranged along the inner side of the modified saline soil filling roadbed. The oblique barrier layer is made of the same material as the barrier layer in Example 1, and the thickness can be the same or different. The oblique barrier layer can be constructed in layers along with the layered construction of the modified saline soil filling roadbed, and the oblique barrier layer 5 can be bonded to the horizontal barrier layer.

[0057] Embodiment 4

[0058] This embodiment provides a construction method for a roadbed structure for comprehensive utilization of bulk saline soil, including the following contents:

[0059] The saline soil is modified by limestone powder and gypsum to obtain the material used for the modified saline soil filling roadbed;

[0060] From bottom to top, the modified saline soil filler roadbed is constructed in layers, and compacted after the layered construction;

[0061] When the modified saline soil filler roadbed is constructed to the set height, the barrier layer is laid. During the construction of the barrier layer, the saline soil, cement, foaming agent and water are mixed to form saline soil base foam lightweight soil;

[0062] After the construction of the barrier layer is completed, the modified saline soil filling roadbed is continued to be constructed on the top of the barrier layer until the modified saline soil filling roadbed reaches the top.

[0063] In this way, by using modified saline soil filling roadbed and saline soil base foam lightweight soil as a barrier layer, these two engineering measures can not only reasonably utilize the saline soil distributed in large quantities along the highway, but also ensure the long-term service performance of the roadbed.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A roadbed structure for comprehensive utilization of bulk saline soil, characterized in that: It includes a modified saline soil filling roadbed. The cross-section of the modified saline soil filling roadbed is a trapezoid that is narrow at the top and wide at the bottom. A partition layer is laid in the modified saline soil filling roadbed. The partition layer adopts saline soil-based foam lightweight soil. The height between the partition layer and the top of the modified saline soil filling roadbed is smaller than the height between the partition layer and the bottom of the modified saline soil filling roadbed. The components of the modified saline soil filling roadbed are saline soil, limestone powder and gypsum, and the components of the saline soil-based foam lightweight soil are saline soil, cement, foaming agent and water.

2. A roadbed structure for comprehensive utilization of bulk saline soil according to claim 1, characterized in that: The thickness of the barrier layer is 0.25-0.4 m, and the barrier layer and the top plane of the modified saline soil filling roadbed are arranged parallel to each other.

3. The roadbed structure for comprehensive utilization of bulk saline soil according to claim 1, characterized in that: The height between the isolation layer and the top of the modified saline soil filling roadbed is 0.8-1.2m.

4. The roadbed structure for comprehensive utilization of bulk saline soil according to claim 1, characterized in that: The length of the isolation layer is less than or equal to the length of the modified saline soil filling roadbed where it is located, and the width of the isolation layer is less than or equal to the width of the modified saline soil filling roadbed where it is located at the transverse section.

5. The roadbed structure for comprehensive utilization of bulk saline soil according to claim 1, characterized in that: The components of the saline soil, limestone powder and gypsum in the modified saline soil filling roadbed are 60%-75%, 15%-26% and 10%-18%.

6. The roadbed structure for comprehensive utilization of bulk saline soil according to claim 1, characterized in that: The components of saline soil, cement, foaming agent and water in the saline soil-based foamed lightweight soil are 40-50%, 16-25%, 6%-10% and 25%-35%.

7. The roadbed structure for comprehensive utilization of bulk saline soil according to claim 1, characterized in that: The modified saline soil filling roadbed is paved with geocells, which are filled with the saline soil-based foamed lightweight soil.

8. The roadbed structure for comprehensive utilization of bulk saline soil according to claim 7, characterized in that: Along the height direction of the modified saline soil filling roadbed, the geocells are arranged in multiple layers, wherein one layer of geocells is arranged on the upper side of the isolation layer, and at least one layer of geocells is arranged on the lower side of the isolation layer.

9. The roadbed structure for comprehensive utilization of bulk saline soil according to claim 1, characterized in that: A roadbed is arranged inside the modified saline soil filling roadbed, the bottom of the roadbed is flush with the top of the barrier layer, and the top of the roadbed is flush with the top of the modified saline soil filling roadbed.

10. A construction method for a roadbed structure for comprehensive utilization of bulk saline soil, characterized in that: It includes the following: The saline soil is modified by limestone powder and gypsum to obtain the material used for the modified saline soil filling roadbed; From bottom to top, the modified saline soil filler roadbed is constructed in layers, and compacted after the layered construction; When the modified saline soil filler roadbed is constructed to the set height, the barrier layer is laid. During the construction of the barrier layer, the saline soil, cement, foaming agent and water are mixed to form saline soil base foam lightweight soil; After the construction of the barrier layer is completed, the modified saline soil filler roadbed is constructed on the top of the barrier layer.

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