A shield slag solidification method based on material particle skeleton finding

Abstract

The present invention relates to the technical field of shield slag recycling, and in particular to a shield slag solidification method based on material particle skeleton profiling, comprising the following steps: S1, collecting shield slag from a shield tunnel construction site, removing impurities in the shield slag, and obtaining screened slag; S2, drying the screened slag to obtain dry slag; S3, obtaining material particles with a loose porous structure; S4, mixing the dry slag with the material particles, and obtaining transition slag after uniform mixing; S5, mixing the transition slag with cement, lime and water, and obtaining solidified soil after uniform mixing; by adding material particles of different particle sizes to optimize and improve the particle composition of the slag itself, and combining the solidification effect of cement and other curing agents, under the condition of forming the basic strength of the solidified soil, the strength is improved and good stability is formed by particle skeleton profiling, and finally the solidified soil can be used for roadbed filling of all highway grades such as expressways.

Description

Technical Field

[0001] The invention relates to the technical field of shield slag recycling, and in particular to a shield slag solidification method based on material particle skeleton profiling. Background Art

[0002] Shield construction is widely used in underground projects such as tunnels and subways, and the treatment of the large amount of slag generated has become an important issue. Traditionally, these slags are mostly treated as waste, such as landfills and piles, which not only increases the environmental burden, but also wastes resources.

[0003] In order to solve the problem of shield slag treatment, in recent years, researchers have begun to explore the possibility of converting shield slag into engineering materials. However, due to the complex nature of shield slag and its poor characteristics, the traditional method of using a single curing agent such as cement or a composite curing agent such as cement and lime from the perspective of an improver increases the cost of solidifying soil, making it difficult for solidified soil to be applied from the laboratory to engineering due to cost issues; on the other hand, the effect after solidification is not ideal, and the water stability and long-term durability cannot withstand the test, so the solidified soil has to be used in low-requirement application scenarios such as site leveling and river pond backfilling. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a shield slag solidification method based on material particle skeleton finding, which optimizes and improves the particle composition of the slag itself by adding material particles of different particle sizes, and combines the solidification effect of curing agents such as cement. Under the condition of forming the basic strength of the solidified soil, the particle skeleton finding (through objects of different particle sizes, step by step filling each other (called finding) to achieve a dense skeleton structure) is used to improve the strength and form good stability. Finally, the solidified soil can be used for roadbed filling of all highway grades such as expressways.

[0005] A shield slag solidification method based on material particle skeleton profiling of the present invention comprises the following steps:

[0006] S1, collecting shield slag from the shield tunnel construction site, and removing impurities in the shield slag by screening to obtain screened slag;

[0007] Shield slag may contain various non-soil materials, such as metal fragments, plastics, wood, etc. These impurities will not only interfere with the subsequent processing process, but also affect the quality and performance of the final product. Screening can effectively remove the above impurities and ensure the quality and performance of the final product.

[0008] By pre-screening and removing unnecessary components, unnecessary resource consumption in the subsequent processing process can be reduced, such as reducing the time and energy required for drying, which indirectly reduces the cost of the entire processing process;

[0009] S2, drying the screened slag to obtain dry slag;

[0010] When the shield machine is digging underground, it often encounters groundwater or wet strata, resulting in high moisture content in the collected soil. The soil with high moisture content has poor fluidity and is difficult to mix evenly with other materials. Drying treatment can control the moisture content of the soil within a relatively ideal range. The dried soil has better fluidity and uniformity, which helps to form a tighter particle skeleton structure in the subsequent mixing process, thereby enhancing the mechanical properties of the solidified soil.

[0011] Among them, the drying process can be carried out by natural drying, hot air drying, microwave drying, drum drying, vacuum drying, etc.

[0012] S3, obtaining material particles with a loose porous structure; the material particles include coarse materials and fine materials;

[0013] Among them, the coarse material provides spatial skeleton support, which can effectively support the weight of the structure and provide the overall stability of the material; the fine material and slag gradually fill the gaps between the skeletons to form a dense structure. By controlling the ratio of slag, coarse material and fine material, the void ratio of the particles is minimized, achieving dual optimization of the internal skeleton support and dense filling of the material, and improving the strength and stability of the material;

[0014] In the present invention, the coarse material needs to have sufficient porosity (e.g., 50-60%) to ensure the embedding space of the fine material and the slag, and the specific surface area is controlled within a certain range (e.g., 10-30m 2 / g) to avoid excessive dispersion between particles and affect the supporting force. Fine materials are embedded in the pores of large particles. Through the close contact and interlocking force between particles, local bite effect is formed, which greatly enhances the mechanical properties of the solidified soil. The slag particles are used as the finest filling material to further optimize the connection between particles and construct a composite mechanical structure.

[0015] At the same time, material particles with loose porous structure are selected. The loose porous structure allows the slag to be embedded to form a firm "imitation rivet" structure, which further ensures the strength and stability of the solidified soil.

[0016] S4, mixing the dry slag and the material particles in proportion, and mixing them evenly to obtain transition slag;

[0017] Reasonable mixing enables material particles of different particle sizes and dry slag to effectively fill the gaps between each other, optimizes the overall particle grading, and further improves density and strength;

[0018] S5, mixing the transition slag with cement, lime and water in proportion, and mixing them evenly to obtain solidified soil;

[0019] Cement and lime are the main curing agents. When water is added, a series of hydration reactions will be initiated. The hydration products generated by these reactions not only enhance the bonding force between the slag particles, but also chemically bond with the surface of the material particles, further strengthening the entire system.

[0020] The above steps significantly improve the effect of shield slag treatment and the performance of the final product. Specifically, the removal of impurities by screening ensures the purity of the subsequent treatment process and improves the quality and performance of the final solidified soil. At the same time, the pre-removal of unnecessary components reduces the resource consumption in drying and other treatment processes and reduces the overall process cost. The drying treatment improves the fluidity and uniformity of the slag, further saving energy and time. The selection of loose porous structured material particles and mixing them with dry slag to form an "imitation rivet" structure greatly enhances the compressive strength, cohesion and stability of the solidified soil, laying a solid foundation for the realization of high-strength and high-stability engineering materials. Finally, cement and lime are added as curing agents and fully mixed to initiate the hydration reaction. The generated hydration products not only strengthen the bonding force between the slag particles, but also chemically bond with the surface of the material particles, thereby further strengthening the entire system and improving the overall performance of the solidified soil.

[0021] As a preferred embodiment of the present invention, the material particles are slag;

[0022] The surface of slag has a rich loose porous structure, which allows shield slag particles to be embedded in it to form a strong "rivet-like" structure. This structure greatly enhances the mechanical interlocking effect of the solidified soil and improves the compressive strength and stability; the porous characteristics of slag provide a larger surface area, which is conducive to cement, lime and other curing agents to more fully contact and chemically react with the slag, which not only accelerates the reaction process, but also ensures the thoroughness and uniformity of the reaction, thereby improving the overall mechanical properties of the solidified soil; using slag is a way of recycling waste, reducing the emission of industrial waste, and is in line with the concept of sustainable development. At the same time, compared with other possible material particles, slag has a lower cost, which helps to reduce overall processing costs.

[0023] As a preferred embodiment of the present invention, in step S4, the coarse material forms a spatial skeleton structure for the fine material and the dry slag to fill, and the fine material and the dry slag are gradually filled into the gaps of the skeleton structure to form an overall internal dense structure;

[0024] In step S4, a spatial skeleton structure is constructed by coarse materials, and fine materials and dry slag are gradually filled into the gaps of the skeleton structure to form an overall internal dense structure, thereby significantly improving the structural strength of the solidified soil, optimizing the density, reducing the internal porosity, preventing moisture and air penetration, and ensuring the uniform distribution of the various components, avoiding the problem of local over-density or sparseness, improving the stability and uniformity of the solidified soil, enhancing the erosion resistance and durability, making it more suitable for engineering applications exposed to harsh environments for a long time, and increasing the surface area, which is beneficial to the chemical reaction between curing agents such as cement and lime and slag, promoting the curing process and accelerating the hardening speed.

[0025] As a preferred embodiment of the present invention, the particle size of the fine material is 0.075-2 mm, and the particle size of the coarse material is 2-4 mm;

[0026] By utilizing the particle skeleton between material particles of different particle sizes and slag, slag with a particle size of 2-4mm is used as the skeleton material to provide physical support for the entire mixture, preventing excessive compaction or excessive fluidity caused by excessive fine particles, and maintaining appropriate structural stability. Slag and slag with a particle size of 0.075-2mm are gradually filled into the gaps of slag with a particle size of 2-4mm, forming an overall dense internal structure of the solidified soil, further ensuring the strength and stability of the solidified soil.

[0027] As a preferred embodiment of the present invention, the ratio of 0.075-2 mm slag: 2-4 mm slag: dry slag is 5-15: 10-30: 50-90;

[0028] The above ratio can ensure the best physical and chemical compatibility between the components, thus significantly improving the overall performance of the solidified soil. Specifically, the smaller particle size of 0.075-2mm slag can fill the gaps between the larger particle size of 2-4mm slag to form a tight and orderly spatial skeleton structure, while the larger proportion of dry slag is gradually filled into this skeleton, making the entire structure more compact, reducing the internal porosity, and enhancing the structural strength and stability. In addition, such a ratio helps to promote the chemical reaction between cement, lime and other curing agents and slag, accelerate the curing process and increase the hardening speed, while optimizing the physical properties of the solidified soil such as density, strength and permeability, making it more suitable for different engineering needs and usage scenarios. Finally, by reasonably adjusting the proportion of each component, the characteristics of the solidified soil can be customized according to the specific construction conditions to achieve the best engineering application effect.

[0029] As a preferred embodiment of the present invention, the ratio of 0.075-2mm slag: 2-4mm slag: dry slag is 10:20:70; according to the particle size of each level of slag and the particle size of the slag, according to this ratio, different particle sizes can be filled with each other to achieve a dense skeleton structure.

[0030] As a preferred embodiment of the present invention, the moisture content of the dried slag is 15%;

[0031] A moisture content of 15% provides ideal hydration conditions for curing agents such as cement and lime, allowing these curing agents to fully contact and react chemically with soil particles. The right amount of water starts and maintains the hydration reaction, while excess water will not dilute the curing agent or cause unnecessary premature reaction.

[0032] As a preferred embodiment of the present invention, the addition ratio of cement, lime and water in step S5 is 1-5%, 0.5-2% and 1-5% of the weight of the mixture of cement, lime, water and transition slag, respectively; in the present invention, cement, lime and water are used as admixtures, combined with the formed dense skeleton structure, and the overall stress strength is improved through chemical reaction. Preferably, the addition ratio of cement, lime and water is 2%, 1% and 3% of the weight of the mixture of cement, lime, water and transition slag, respectively. The engineering cost is reduced while ensuring the strength. The amount of water can be adjusted according to the dryness and wetness of the soil and the optimal moisture content, depending on the difference to ensure the application effect.

[0033] 1-5% cement and 0.5-2% lime provide sufficient active ingredients to react chemically with the mineral components in the slag to produce hydration products such as calcium hydroxide and calcium silicate, which fill and cement the gaps between the slag particles to form a strong solid structure;

[0034] 1-5% water provides sufficient moisture to start and maintain the hydration reaction, while avoiding the negative impact of excessive moisture on the curing effect. The right amount of moisture helps to improve density, reduce the risk of shrinkage cracks, and ensure the quality of the final product.

[0035] As a preferred solution of the present invention, the addition ratios of cement, lime and water are 2%, 1% and 3% of the weight of the mixture of cement, lime, water and transition slag respectively.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) By using the particle skeleton between material particles and slag of different particle sizes to find the shape, the coarse material with large particle size forms the spatial skeleton structure of the mixture of material particles and slag, and the fine material with small particle size and slag are gradually filled into the gaps of the skeleton structure, forming a dense structure inside the solidified soil as a whole. The material particles are selected from slag with a loose and porous surface. The loose and porous surface allows the slag to be embedded to form a firm "imitation rivet" structure, which further ensures the strength and stability of the solidified soil.

[0038] (2) By scientifically and rationally adopting a combination of material particle skeleton shaping and cement consolidation, under the condition that cement consolidation forms the basic strength, the particle skeleton shaping is used to improve the strength and form good stability;

[0039] (3) Turning waste into treasure, effectively utilizing shield slag, reducing land occupation and environmental pollution, and improving the performance and stability of solidified soil so that it can be used as roadbed filler for all highway grades such as expressways;

[0040] (4) This method can reduce the addition ratio of cement and lime by about 2% by replacing part of the cement and lime with material particles, thereby reducing the cost of each cubic meter of solidified soil by 8 yuan, thus alleviating the economic pressure for solidified soil to be applied from the laboratory to engineering;

[0041] (5) The preparation method of this method is simple and clear, easy to operate, suitable for large-scale promotion and application, and provides a new solution for urban infrastructure construction and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic flow diagram of a shield slag solidification method based on material particle skeleton profiling of the present invention. DETAILED DESCRIPTION

[0043] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0044] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0045] Secondly, the term "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0046] Embodiment 1:

[0047] This embodiment provides a shield slag solidification method based on material particle skeleton finding, comprising the following steps:

[0048] S1, collecting shield slag from the shield tunnel construction site, and removing impurities in the shield slag by screening to obtain screened slag;

[0049] S2, drying the screened soil to obtain dry soil with a moisture content of 15%;

[0050] S3, obtaining material particles with a loose porous structure, wherein the material particles are slag;

[0051] S4, mixing the dry slag and the material particles in proportion, mixing for 20 seconds, and obtaining transition slag after mixing evenly; wherein, the ratio of 0.075-2mm slag (fine material): 2-4mm slag (coarse material): dry slag is 5:20:75;

[0052] S5. Mix the transition slag with cement, lime and water in proportion for 40 seconds to obtain solidified soil after uniform mixing; the added proportions of cement, lime and water are 2.3%, 0.8% and 2% of the weight of the mixture of cement, lime, water and transition slag respectively.

[0053] Embodiment 2:

[0054] This embodiment provides a shield slag solidification method based on material particle skeleton finding, comprising the following steps:

[0055] S1, collecting shield slag from the shield tunnel construction site, and removing impurities in the shield slag by screening to obtain screened slag;

[0056] S2, drying the screened soil to obtain dry soil with a moisture content of 15%;

[0057] S3, obtaining material particles with a loose porous structure, wherein the material particles are slag;

[0058] S4, mixing the dry slag and the material particles in proportion, mixing for 20 seconds, and obtaining transition slag after mixing evenly; wherein the ratio of 0.075-2mm slag: 2-4mm slag: dry slag is 10:20:70;

[0059] S5. Mix the transition slag with cement, lime and water in proportion for 40 seconds to obtain solidified soil after uniform mixing; the added proportions of cement, lime and water are 2%, 1% and 3% of the weight of the mixture of cement, lime, water and transition slag respectively.

[0060] Embodiment 3:

[0061] This embodiment provides a shield slag solidification method based on material particle skeleton finding, comprising the following steps:

[0062] S1, collecting shield slag from the shield tunnel construction site, and removing impurities in the shield slag by screening to obtain screened slag;

[0063] S2, drying the screened soil to obtain dry soil with a moisture content of 15%;

[0064] S3, obtaining material particles with a loose porous structure, wherein the material particles are slag;

[0065] S4, mixing the dry slag and the material particles in proportion, mixing for 20 seconds, and obtaining transition slag after mixing evenly; wherein the ratio of 0.075-2mm slag: 2-4mm slag: dry slag is 9:23:68;

[0066] S5. Mix the transition slag with cement, lime and water in proportion for 40 seconds to obtain solidified soil after uniform mixing; the added proportions of cement, lime and water are 2.4%, 1.2% and 3.2% of the weight of the mixture of cement, lime, water and transition slag respectively.

[0067] The solidified soil obtained in Examples 1-3 was tested and the following data were obtained:

[0068] Example 1 Example 2 Example 3 CBR(%) 120 121 116

[0069] The solidified soil prepared in Examples 1-3 not only has excellent mechanical properties, but also exhibits good water stability and durability, fully meeting the various performance requirements of solidified soil for highway roadbed projects, and providing reliable guarantees for practical applications.

[0070] Comparative Example 1:

[0071] S1, collecting shield slag from the shield tunnel construction site, and removing impurities in the shield slag by screening to obtain screened slag;

[0072] S2, drying the screened soil to obtain dry soil with a moisture content of 15%;

[0073] S3. Mix the dry slag with cement and water in proportion for 40 seconds to obtain solidified soil after uniform mixing; the addition ratio of cement and water is 2% and 2% of the weight of the mixture of cement, water and dry slag respectively.

[0074] Comparative Example 2:

[0075] The difference from Comparative Example 1 is that the addition ratios of cement and water are 4% and 2.3% of the weight of the mixture of cement, water and dry slag, respectively.

[0076] Comparative Example 3:

[0077] S1, collecting shield slag from the shield tunnel construction site, and removing impurities in the shield slag by screening to obtain screened slag;

[0078] S2, drying the screened soil to obtain dry soil with a moisture content of 15%;

[0079] S3. Mix the dry slag with lime and water in proportion for 40 seconds to obtain solidified soil after mixing evenly; the added proportions of lime and water are 5% and 3% of the weight of the mixture of lime, water and dry slag respectively.

[0080] Comparative Example 4:

[0081] The difference from Comparative Example 4 is that the added proportions of lime and water are 6% and 3.3% of the weight of the mixture of lime, water and dry slag respectively.

[0082] Comparative Example 5:

[0083] S1, collecting shield slag from the shield tunnel construction site, and removing impurities in the shield slag by screening to obtain screened slag;

[0084] S2, drying the screened soil to obtain dry soil with a moisture content of 15%;

[0085] S3. Mix the dry slag with cement, lime and water in proportion for 40 seconds to obtain solidified soil after uniform mixing; the added proportions of cement, lime and water are 2%, 1% and 3.4% of the weight of the mixture of cement, lime, water and dry slag respectively.

[0086] The solidified soil obtained in Examples 1-5 was tested and the following data were obtained:

[0087] CBR(%) Comparative Example 1 62.7 Comparative Example 2 112.6 Comparative Example 3 56.6 Comparative Example 4 64.5 Comparative Example 5 85.5

[0088] The CBR values ​​of the solidified soils prepared in the above-mentioned embodiments and comparative examples are analyzed. Comparative Examples 1 and 2 are made of dry slag, cement and water. When the amount of cement added is increased to 4%, although the CBR value reaches 112.6, the engineering cost is increased due to the high cost of cement.

[0089] Comparative Examples 3 and 4 were made of dry slag, lime and water. Even if the lime addition amount reached 6%, the CBR value could not reach the minimum requirement of 80;

[0090] Comparative Example 5 is made of dry slag, lime, cement and water. Compared with the example, it lacks the material particles of the present invention. Although the CBR value reaches 85.5, it is far less than the solidified soil produced by the present invention. The present invention scientifically and reasonably adopts a combination of material particle skeleton and cement consolidation. Under the condition that cement consolidation forms basic strength, the particle skeleton is used to improve strength and form good stability.

[0091] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A shield slag solidification method based on material particle skeleton profiling, characterized in that: The following steps are involved: S1, collecting shield slag from the shield tunnel construction site, and removing impurities in the shield slag by screening to obtain screened slag; S2, drying the screened slag to obtain dry slag; S3, obtaining material particles with a loose porous structure; the material particles include coarse materials and fine materials; S4, mixing the dry slag and the material particles in proportion, and mixing them evenly to obtain transition slag; S5, mixing the transition slag with cement, lime and water in proportion, and obtaining solidified soil after mixing evenly.

2. The shield slag solidification method based on material particle skeleton finding according to claim 1 is characterized in that: The material particles are slag.

3. The shield slag solidification method based on material particle skeleton finding according to claim 1 is characterized in that: In the step S4, the coarse material forms a spatial skeleton structure for the fine material and the dry slag to fill, and the fine material and the dry slag are gradually filled into the gaps of the skeleton structure to form an overall internal dense structure.

4. The shield slag solidification method based on material particle skeleton finding according to claim 2 is characterized in that: The particle size of the fine material is 0.075-2 mm, and the particle size of the coarse material is 2-4 mm.

5. The shield slag solidification method based on material particle skeleton finding according to claim 4 is characterized in that: The ratio of 0.075-2mm slag: 2-4mm slag: dry slag is 5-15: 10-30: 50-90.

6. The shield slag solidification method based on material particle skeleton finding according to claim 5 is characterized in that: The ratio of 0.075-2mm slag: 2-4mm slag: dry slag is 10:20:

70.

7. The shield slag solidification method based on material particle skeleton finding according to claim 1 is characterized in that: The moisture content of the dried slag is 15%.

8. The shield slag solidification method based on material particle skeleton finding according to claim 1 is characterized in that: In step S5, the addition ratios of cement, lime and water are 1-5%, 0.5-2% and 1-5% of the weight of the mixture of cement, lime, water and transition slag, respectively.

9. The shield slag solidification method based on material particle skeleton finding according to claim 8, characterized in that: The addition ratios of cement, lime and water are 2%, 1% and 3% of the weight of the mixture of cement, lime, water and transition slag respectively.

Images