Preparation method, product and application of a suction phase change composite material for repairing urban ground subsidence

Abstract

The application relates to a preparation method, product and application of a suction phase change composite material for repairing urban ground subsidence, and belongs to the technical field of material preparation. The method comprises the following steps: S1, porous carbon is mixed into a Na2CO3 solution, ultrasonic treatment and centrifugal treatment are carried out, and a composite material in which Na2CO3 is dispersed in the pore structure of the porous carbon is obtained; S2, the composite material is added into a dialysis bag, sealed, transferred into a CaCl2 solution, taken out after the solution in the dialysis bag completely immerses the composite material, and cleaned with deionized water; S3, the cleaned composite material is dried, transferred into a tube furnace, calcined under the protection of argon, and cooled, so that a composite material in which quicklime is dispersed in the pore structure of the porous carbon is obtained. The method solves the problem that, in a traditional preparation method, a large amount of quicklime is formed on the surface of the porous carbon, the composite material is isolated by the reaction product in the process of water suction, and the function of repairing and improving the bearing capacity of the road surface is lost, so that the service life of the repaired road surface is prolonged.

Description

Technical Field

[0001] This invention belongs to the field of materials preparation technology, specifically relating to a method for preparing, a product of, and an application of a traction-absorption phase change composite material for repairing urban ground subsidence. Background Technology

[0002] Road collapses have become a dangerous problem hindering traffic safety in recent years. The root cause is underground cavities and the infiltration and erosion of water within these cavities. Because road collapses are characterized by their hidden nature, suddenness, and the potential to affect multiple individuals, they seriously threaten the safe operation of urban roads. Therefore, preventing and controlling road collapses in urban areas is of paramount importance.

[0003] When cavities beneath a road contain a large amount of water, the water seeps into and erodes the surrounding soil, reducing the soil's structural strength. As the erosion continues, the effective stress on the soil overlying the cavity weakens, causing it to gradually peel away under gravity. This leads to the expansion of the cavity's area and size, and a gradual decrease in the roadbed's ultimate bearing capacity. When the road load reaches a certain level, the roadbed's soil structure reaches its limit, resulting in a road collapse. Therefore, water seepage and erosion are significant contributing factors to the expansion of soil cavities and even road collapses. How to address the hidden dangers of cavities and water bodies beneath roads in a green and environmentally friendly manner is a crucial research topic for preventing urban road collapses. Currently, most road repair methods involve either excavation or filling, which can further disrupt the road structure. Alternatively, absorbent materials can be used to temporarily absorb water from cavities, but the water remains underground and can still cause road collapse due to subsequent surface disturbances or changes in groundwater levels. This invention proposes a composite material repair method that avoids road excavation disturbance and can remove water through traction, adsorption, and phase change transformation. This method removes water from underground cavities and solidifies and fills the cavities, thereby preventing road subsidence and collapse. Summary of the Invention

[0004] In order to solve the existing problems, this invention provides a method for preparing a traction phase change composite material for repairing urban ground subsidence, as well as the product and its application, to address the problem of ground subsidence.

[0005] A method for preparing a traction phase change composite material for repairing urban ground subsidence includes the following steps: S1. Mixing porous carbon into a Na2CO3 solution, ultrasonically treating for a period of time, and centrifuging to obtain a composite material in which Na2CO3 is dispersed in the porous carbon pore structure, wherein the porous carbon and Na2CO3 have a certain molar ratio. S2. Add the composite material into a dialysis bag and seal it. After sealing, transfer it to a CaCl2 solution. After the solution in the dialysis bag completely submerges the composite material, remove the composite material and wash it with deionized water. S3. After drying the cleaned composite material, it is transferred to a tube furnace and calcined under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon structure is obtained.

[0006] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the porous carbon has a specific surface area of ​​1100~1800 cm². 2 / g, pore volume 0.5~1.0cm³ 3 / g, the molar ratio of porous carbon to Na2CO3 is 1:1 to 4:1.

[0007] In addition to the aspects described above and any possible implementation, a further implementation is provided in which the time period is 20 minutes and the cleaning includes at least three cycles.

[0008] In addition to the aspects described above and any possible implementations, a further implementation is provided in which the molecular cutoff of the dialysis bag is 30~100kDa and the concentration of the CaCl2 solution is 2~6mol / L.

[0009] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the calcination is carried out at a temperature greater than or equal to 850°C and for a calcination time of at least 3 hours.

[0010] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the molar ratio of the porous carbon to Na₂CO₃ is 1:1, the molecular cutoff of the dialysis bag is 50 kDa, and the specific surface area of ​​the porous carbon is 1236 cm⁻¹. 2 / g, pore volume 0.57cm³ 3 / g.

[0011] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the molar ratio of the porous carbon to Na₂CO₃ is 1:1, the molecular cutoff of the dialysis bag is 50 kDa, and the specific surface area of ​​the porous carbon is 1560 cm⁻¹. 2 / g, pore volume is 0.83cm³ 3 / g.

[0012] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the molar ratio of porous carbon to Na2CO3 is 1:1, the molecular cutoff of the dialysis bag is 50 kDa, and the specific surface area of ​​the porous carbon is 1785 cm². 2 / g, pore volume is 0.98cm³ 3 / g.

[0013] The present invention also provides a traction phase change composite material for repairing urban ground subsidence. The composite material is obtained by the preparation method described above, and the composite material has the properties of traction phase change and quicklime existing only in the porous carbon pore structure.

[0014] This invention also provides an application of composite materials in the repair of urban ground subsidence.

[0015] Beneficial effects of the present invention The preparation method of this invention ensures that carbonates and calcium salts react only within the pore structure of porous carbon, not on its surface. This ensures that quicklime does not form on the surface of the porous carbon, but only within its pore structure. This solves the problem of traditional methods where the large amount of quicklime formed on the surface of porous carbon leads to the composite material being easily isolated by reaction products during the traction and water absorption process, thus losing its ability to repair and improve the road surface bearing capacity. Simultaneously, the composite material prepared by this method allows the same amount of quicklime to be evenly dispersed in a larger space, resulting in a larger traction and water absorption range and more uniform heat dissipation during phase change, leading to more effective water drainage. Furthermore, when the prepared composite material is placed in water-bearing, loose, or cavitary underground soil, it can attract and absorb water. During the reaction between water and the composite material, the water phase changes to gas and evaporates, disappearing from the soil. This further enhances the strength of the composite material and strengthens its adhesion to the soil, significantly improving the overall stability of the underground soil, reducing the probability of ground subsidence, and extending its service life. Attached Figure Description

[0016] Figure 1 This is a flowchart of the preparation method of the present invention. Detailed Implementation

[0017] To better understand the technical solution of this invention, the content of this invention includes, but is not limited to, the specific embodiments described below. Similar technologies and methods should be considered within the scope of protection of this invention. To make the technical problem to be solved, the technical solution, and the advantages of this invention clearer, a detailed description will be provided below in conjunction with the accompanying drawings and specific embodiments.

[0018] It should be understood that the embodiments described in this invention are merely some embodiments of this invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0019] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0020] like Figure 1 As shown, the present invention provides a method for preparing a composite material for repairing urban ground subsidence, comprising: S1. mixing porous carbon into a Na2CO3 solution, ultrasonically treating for a period of time, and centrifuging to obtain a composite material in which Na2CO3 is dispersed in the porous carbon pore structure, wherein the porous carbon and Na2CO3 have a certain molar ratio; S2. Add the composite material into a dialysis bag and seal it. After sealing, transfer it to a CaCl2 solution. After the solution in the dialysis bag completely submerges the composite material, remove the composite material and wash it with deionized water. S3. After drying the cleaned composite material, it was transferred to a tube furnace and calcined under argon protection. After cooling, a composite material with quicklime dispersed in a porous carbon structure was obtained. Specifically, the process of this invention is as follows: Steps: (1) Add porous carbon to a solution containing Na2CO3 and sonicate for 20 min. The specific surface area of ​​the porous carbon is 1100~1800 cm³. 2 / g, pore volume 0.5~1.0cm³ 3 / g, the molar ratio of porous carbon to Na2CO3 is 1:1~4:1; This range ensures that porous carbon can fully absorb Na2CO3 while still maintaining high strength.

[0021] The product obtained in step (1) was centrifuged to obtain a composite material in which Na2CO3 was dispersed in a porous carbon pore structure. Centrifugation ensures the removal of Na2CO3 solution that is not adsorbed within the porous carbon pores, resulting in a composite material containing only Na2CO3 within the porous carbon pore structure.

[0022] The composite material obtained in step (2) is added into a dialysis bag with a molecular cutoff of 30~100kDa, sealed, and then transferred to a CaCl2 solution with a concentration of 2~6mol / L. If the molecular cutoff of the dialysis bag is too small or the concentration of the CaCl2 solution is too high, it cannot be guaranteed that the CaCl2 solution will fully enter the dialysis bag and react with the Na2CO3 in the porous carbon pores. If the molecular cutoff of the dialysis bag is too large or the concentration of the CaCl2 solution is too low, a large amount of CaCl2 solution will enter instantaneously and come into contact with the porous carbon pores. This will cause the solvent water in the CaCl2 solution to leach the Na2CO3 in the porous carbon pore structure, resulting in a composite material with quicklime CaO dispersed on the surface of the porous carbon after high-temperature calcination, rather than a composite material with quicklime dispersed only in its pore structure.

[0023] (4) After the solution in the dialysis bag has completely submerged the composite material, remove the composite material and rinse it three times with deionized water; (5) After drying the composite material obtained in step (3), transfer it to a tube furnace and calcine it for 3 hours under the protection of argon. After cooling, a composite material with a porous carbon pore structure filled with quicklime is obtained. The calcination temperature is ≥850℃. The calcination temperature needs to be ≥850℃ to ensure that calcium carbonate decomposes to form quicklime.

[0024] As an embodiment of the present invention, the present invention also provides a composite material for repairing ground subsidence. The composite material is obtained using the aforementioned preparation method. The composite material possesses the properties of a traction-absorption phase change and quicklime existing only in the porous carbon pore structure. The abundant and uniform pore structure provided by the activated carbon enables traction water absorption and allows the same amount of quicklime to be uniformly dispersed in a larger space, resulting in more uniform heat dissipation and more effective water discharge during the traction-absorption phase change process. The structural characteristic of this composite material, where quicklime is only filled in the porous carbon pore structure, solves the problem that composite materials prepared by traditional methods, due to the large amount of quicklime forming on the porous carbon surface, are easily isolated by reaction products during the traction-absorption process, thus losing their function of repairing and improving the road surface bearing capacity.

[0025] As an embodiment of the present invention, this invention also provides an application of composite materials in the repair of urban ground subsidence. The composite material is placed into water-bearing, loose, or cavitary soil to complete the repair. The composite material particles prepared by this invention, when placed into water-bearing, loose, or cavitary soil, can attract and absorb groundwater, further causing a liquid-gas phase transition. The gaseous water is then discharged through the soil pores, simultaneously filling cavities and consolidating with the overlying soil to improve the roadbed strength and ultimate bearing capacity. Furthermore, the composite material's structure, which only contains quicklime in a porous carbonaceous structure, significantly increases the dispersion area of ​​the quicklime, thereby controlling the reaction rate between quicklime and water during the cavity repair process. This prevents damage to the roadbed due to the instantaneous generation of large amounts of heat, ultimately resulting in rapid, uniform, and stable drainage of water.

[0026] The present invention will be further illustrated below with examples and comparative examples.

[0027] Example 1 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 1:1, and the specific surface area of ​​the porous carbon is 1236 cm³. 2 / g, pore volume 0.57cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 50 kDa, seal it, and transfer it to 10 L of CaCl2 solution with a concentration of 3 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0028] Example 2 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 2:1, and the specific surface area of ​​the porous carbon is 1236 cm³. 2 / g, pore volume 0.57cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 50 kDa, seal it, and transfer it to 10 L of CaCl2 solution with a concentration of 3 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0029] Example 3 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 3:1, and the specific surface area of ​​the porous carbon is 1236 cm³.2 / g, pore volume 0.57cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 50 kDa, seal it, and transfer it to 10 L of CaCl2 solution with a concentration of 3 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0030] Example 4 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 4:1, and the specific surface area of ​​the porous carbon is 1236 cm³. 2 / g, pore volume 0.57cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 50 kDa, seal it, and transfer it to 10 L of CaCl2 solution with a concentration of 3 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0031] Example 5 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 1:1, and the specific surface area of ​​the porous carbon is 1560 cm³. 2 / g, pore volume is 0.83cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 50 kDa, seal it, and transfer it to 10 L of CaCl2 solution with a concentration of 3 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0032] Example 6 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 1:1, and the specific surface area of ​​the porous carbon is 1785 cm³. 2 / g, pore volume is 0.98cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 50 kDa, seal it, and transfer it to 10 L of CaCl2 solution with a concentration of 3 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0033] Example 7 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 1:1, and the specific surface area of ​​the porous carbon is 1236 cm³. 2 / g, pore volume 0.57cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 50 kDa, seal it, and transfer it to 10 L of CaCl2 solution with a concentration of 3 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), it is transferred to a tube furnace and calcined at 1300℃ for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0034] Example 8 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 1:1, and the specific surface area of ​​the porous carbon is 1236 cm³. 2 / g, pore volume 0.57cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 50 kDa, seal it, and then transfer it into 15 L of CaCl2 solution with a concentration of 2 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0035] Example 9 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 1:1, and the specific surface area of ​​the porous carbon is 1236 cm³. 2 / g, pore volume 0.57cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 50 kDa, seal it, and transfer it to 5 L of CaCl2 solution with a concentration of 6 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0036] Example 10 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 1:1, and the specific surface area of ​​the porous carbon is 1236 cm³. 2 / g, pore volume 0.57cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 30 kDa, seal it, and transfer it to 10 L of CaCl2 solution with a concentration of 3 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0037] Example 11 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 1:1, and the specific surface area of ​​the porous carbon is 1236 cm³. 2 / g, pore volume 0.57cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 100 kDa, seal it, and transfer it to 10 L of CaCl2 solution with a concentration of 3 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0038] Comparative Example 1 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Mix 10L of 2mol / L Na2CO3 solution and 10L of 3mol / L CaCl2 solution and let stand for 20min; (2) The product obtained in step (1) is centrifuged and washed three times with deionized water; (3) The material obtained in step (2) is mixed with porous carbon at a molar ratio of 1:1 and placed in a container filled with deionized water and sonicated for 20 min. (4) After drying the mixture obtained in step (3), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material of porous carbon and quicklime is obtained. (5) Place the composite material obtained in step (4) into the water-bearing underground loose or cavitary soil to complete the repair.

[0039] Comparative Example 2 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 1:1, and the specific surface area of ​​the porous carbon is 1236 cm³. 2 / g, pore volume 0.57cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into 10L of CaCl2 solution with a concentration of 3mol / L and let it stand for 20min; (4) The product obtained in step (3) is centrifuged and washed three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. The above process does not use standard bags for sealing. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0040] Comparative Example 3 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 4.5:1, and the specific surface area of ​​porous carbon is 1236 cm³. 2 / g, pore volume 0.57cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 50 kDa, seal it, and transfer it to 10 L of CaCl2 solution with a concentration of 3 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0041] Comparative Example 4 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 6:1, and the specific surface area of ​​the porous carbon is 1236 cm³. 2 / g, pore volume 0.57cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 50 kDa, seal it, and transfer it to 10 L of CaCl2 solution with a concentration of 3 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0042] Comparative Example 5 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 1:2, and the specific surface area of ​​the porous carbon is 1236 cm³. 2 / g, pore volume 0.57cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 50 kDa, seal it, and transfer it to 10 L of CaCl2 solution with a concentration of 3 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0043] Comparative Example 6 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 1:4, and the specific surface area of ​​the porous carbon is 1236 cm³. 2 / g, pore volume 0.57cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 50 kDa, seal it, and transfer it to 10 L of CaCl2 solution with a concentration of 3 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0044] Comparative Example 7 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 1:1, and the specific surface area of ​​the porous carbon is 727 cm³. 2 / g, pore volume is 0.22cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 50 kDa, seal it, and transfer it to 10 L of CaCl2 solution with a concentration of 3 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0045] Comparative Example 8 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 1:1, and the specific surface area of ​​the porous carbon is 913 cm³. 2 / g, pore volume is 0.38cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 50 kDa, seal it, and transfer it to 10 L of CaCl2 solution with a concentration of 3 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0046] Comparative Example 9 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 1:1, and the specific surface area of ​​the porous carbon is 1236 cm³. 2 / g, pore volume 0.57cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 50 kDa, seal it, and transfer it to 10 L of CaCl2 solution with a concentration of 3 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 650°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0047] Comparative Example 10 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 1:1, and the specific surface area of ​​the porous carbon is 1236 cm³. 2 / g, pore volume 0.57cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 50 kDa, seal it, and transfer it to 10 L of CaCl2 solution with a concentration of 3 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 550°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0048] Comparative Example 11 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 1:1, and the specific surface area of ​​the porous carbon is 1236 cm³. 2 / g, pore volume 0.57cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 50 kDa, seal it, and transfer it to 10 L of CaCl2 solution with a concentration of 7 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0049] Comparative Example 12 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 1:1, and the specific surface area of ​​the porous carbon is 1236 cm³. 2 / g, pore volume 0.57cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 50 kDa, seal it, and transfer it to 10 L of CaCl2 solution with a concentration of 9 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0050] Comparative Example 13 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 1:1, and the specific surface area of ​​the porous carbon is 1236 cm³. 2 / g, pore volume 0.57cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 50 kDa, seal it, and transfer it to 60 L of 0.5 mol / L CaCl2 solution; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0051] Comparative Example 14 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 1:1, and the specific surface area of ​​the porous carbon is 1236 cm³. 2 / g, pore volume 0.57cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 50 kDa, seal it, and transfer it to 30 L of CaCl2 solution with a concentration of 1 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0052] Comparative Example 15 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 1:1, and the specific surface area of ​​the porous carbon is 1236 cm³. 2 / g, pore volume 0.57cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 10 kDa, seal it, and transfer it to 10 L of CaCl2 solution with a concentration of 3 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair; Comparative Example 16 A method for preparing, producing, and applying a traction phase change composite material for repairing urban ground subsidence includes the following steps: (1) Add an appropriate amount of porous carbon to 10 L of 2 mol / L Na2CO3 solution and sonicate for 20 min. The molar ratio of porous carbon to Na2CO3 is 1:1, and the specific surface area of ​​the porous carbon is 1236 cm³. 2 / g, pore volume 0.57cm³ 3 / g; (2) A composite material with Na2CO3 dispersed in a porous carbon structure was obtained by centrifugation; (3) Add the composite material obtained in step (2) into a dialysis bag with a molecular cutoff of 120 kDa, seal it, and transfer it to 10 L of CaCl2 solution with a concentration of 3 mol / L; (4) After the solution in step (3) has completely submerged the composite material in the dialysis bag, remove the composite material and wash it three times with deionized water; (5) After drying the composite material obtained in step (4), transfer it to a tube furnace and calcine it at 950°C for 3 hours under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon pore structure is obtained. (6) Place the composite material obtained in step (5) into the water-bearing underground loose or cavitary soil to complete the repair.

[0053] Table 1 below compares the unconfined compressive strength of the subgrade, the resilient modulus of the subgrade after collapse repair, and the improvement rate of the ultimate bearing capacity of the subgrade after collapse repair of the composite materials prepared in each embodiment and comparative example after ground repair.

[0054] Table 1 Comparison of unconfined compressive strength, resilient modulus of subgrade after collapse repair, and improvement rate of ultimate bearing capacity of subgrade after collapse repair for various composite material subgrades (all data in the table are rounded to two decimal places, and integers in the table are assumed to have a decimal part of 0, so they are omitted). By utilizing the adsorption properties of porous carbon and the flow control effect of dialysis bags, and by limiting the molecular rejection amount of the dialysis bag, the solution concentration, and the characteristics of the porous carbon, a composite material in which quicklime is dispersed only in the pore structure of the porous carbon was prepared. As can be seen from the table, the composite material prepared by the method of this invention has significantly higher strength. When placed in water-bearing, loose, or cavitary underground soil, the composite materials prepared in Examples 1-11 can increase the resilient modulus and ultimate bearing capacity of the repaired subgrade by as much as 57.20%~58.90% and 76.90%~89.90%, respectively, which is significantly higher than the 0.30%~5.30% and 2.00%~4.60% of Comparative Examples 1-16, indicating that the material prepared by this invention has excellent repair capabilities.

[0055] The foregoing description illustrates and describes several preferred embodiments of the present invention. However, as previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A method for preparing, a product of, and an application of a traction-absorption phase change composite material for repairing urban ground subsidence, characterized in that, The process includes the following steps: S1. Mixing porous carbon into a Na2CO3 solution, ultrasonically treating for a period of time, and centrifuging to obtain a composite material in which Na2CO3 is dispersed in the porous carbon pore structure, wherein the porous carbon and Na2CO3 have a certain molar ratio; S2. Add the composite material into a dialysis bag and seal it. After sealing, transfer it to a CaCl2 solution. After the solution in the dialysis bag completely submerges the composite material, remove the composite material and wash it with deionized water. S3. After drying the cleaned composite material, it is transferred to a tube furnace and calcined under the protection of argon. After cooling, a composite material with quicklime dispersed in a porous carbon structure is obtained.

2. The method according to claim 1, characterized in that, The specific surface area of ​​the porous carbon is 1100~1800 cm². 2 / g, pore volume 0.5~1.0cm³ 3 / g, the molar ratio of porous carbon to Na2CO3 is 1:1 to 4:

1.

3. The method according to claim 1, characterized in that, The time period is 20 minutes, and the cleaning includes at least three times.

4. The method according to claim 1, characterized in that, The dialysis bag has a molecular cutoff of 30-100 kDa, and the CaCl2 solution has a concentration of 2-6 mol / L.

5. The method according to claim 1, characterized in that, The calcination temperature is greater than or equal to 850℃, and the calcination time is at least 3 hours.

6. The method according to claim 2, characterized in that, The molar ratio of porous carbon to Na₂CO₃ is 1:1, the molecular cutoff of the dialysis bag is 50 kDa, and the specific surface area of ​​the porous carbon is 1236 cm⁻¹. 2 / g, pore volume 0.57cm³ 3 / g.

7. The method according to claim 2, characterized in that, The molar ratio of porous carbon to Na₂CO₃ is 1:1, the molecular cutoff of the dialysis bag is 50 kDa, and the specific surface area of ​​the porous carbon is 1560 cm⁻¹. 2 / g, pore volume is 0.83cm³ 3 / g.

8. The method according to claim 2, characterized in that, The molar ratio of porous carbon to Na₂CO₃ is 1:1, the molecular cutoff of the dialysis bag is 50 kDa, and the specific surface area of ​​the porous carbon is 1785 cm⁻¹. 2 / g, pore volume is 0.98cm³ 3 / g.

9. A traction phase change composite material for repairing urban ground subsidence, characterized in that, The composite material is obtained by the preparation method according to any one of claims 1-8, and the composite material has the properties of pull-in phase transformation and quicklime existing only in the porous carbon pore structure.

10. The application of the composite material of claim 9 in the repair of urban ground subsidence.

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