A fluidized solidified soil based on shield muck and synergistic multi-source solid waste and a preparation method thereof

Abstract

The application discloses a kind of based on shield slag cooperates multi-source solid waste of flow state solidified soil and preparation method thereof, the flow state solidified soil is composed of gradient activation shield slag, activated multi-source solid waste cementing material, activated shield wastewater, composite activator, functional admixture and layered double hydroxide.The application is classified after shield slag, and fine mud component is handled by "mechanical-chemical-thermal" three-level activation treatment, then with coarse skeleton component, fine filling component is mixed to form gradient activation shield slag;Activated multi-source solid waste cementing material is compounded after being differentially activated by lithium slag powder, electrolytic manganese slag powder, nickel slag powder, alkali residue, desulfurization gypsum and nano silica;Activated shield wastewater is treated by magnetization device after precipitation filtration.The application realizes the resource utilization of shield slag and various industrial solid wastes, and the obtained flow state solidified soil has good fluidity, water retention and mechanical strength, and can be widely applied to backfill and reinforcement engineering.

Description

Technical Field

[0001] This invention belongs to the field of civil engineering materials and solid waste resource utilization technology, specifically involving a fluidized solidified soil based on shield tunneling slag and multi-source solid waste and its preparation method, which is applicable to engineering fields such as backfilling of fertilizer trenches, backfilling of foundation pits, backfilling of pipeline trenches, mine filling and roadbed reinforcement. Background Technology

[0002] With the rapid development of urban rail transit and underground space development in my country, the amount of tunnel boring machine (TBM) excavated soil generated by shield tunneling has been increasing year by year. As engineering waste, most TBM excavated soil is currently disposed of through open-air dumping or landfilling, which not only occupies a large amount of land resources, but also the residual foaming agents, polymers, and other modifying materials in the excavated soil may leach into the groundwater and pollute groundwater and surface water. At the same time, my country also generates a large amount of industrial solid waste every year, and the comprehensive utilization rate of this solid waste is generally low, resulting in enormous storage pressure.

[0003] Fluidized solidified soil, as a novel backfill material, can be constructed through pumping or casting. It is suitable for narrow spaces where traditional compaction processes are difficult to implement and has demonstrated unique functional advantages in projects such as pipe gallery trenches, deep foundation pits of buildings, and mining goaf areas. However, existing fluidized solidified soil technologies still have the following shortcomings: the grading and treatment of tunnel boring machine (TBM) slag is mostly limited to physical screening, failing to fully explore its cementing potential; there is a lack of targeted treatment measures for the negative impacts of residual foaming agents, polymers, and other additives in TBM slag, which may interfere with the hydration reaction of the cementing system and reduce the strength of the solidified soil, but existing technologies lack effective means to eliminate this; the activation treatment methods for solid waste are relatively simple, mainly relying on physical grinding, without fully considering the differences in mineral phase characteristics of different solid waste components. Summary of the Invention

[0004] To address the shortcomings of the existing technology, this invention provides a fluidized solidified soil based on shield tunneling slag and multi-source solid waste, and its preparation method.

[0005] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a fluidized solidified soil based on shield tunneling slag and multi-source solid waste, comprising the following components by mass parts: 1200-1700 parts of cascade-activated shield tunneling slag, 350-650 parts of activated multi-source solid waste cementitious material, 250-380 parts of activated shield tunneling wastewater, 80-160 parts of composite activator, 2-8 parts of polycarboxylate superplasticizer, 0.5-2 parts of hydroxypropyl methylcellulose ether, 0.5-2 parts of starch ether, 0.5-2 parts of air-entraining agent, 1-3 parts of defoamer, 2-8 parts of calcium formate, 0.5-2 parts of sodium aluminate, and 3-10 parts of layered bimetallic hydroxide.

[0006] As a preferred technical solution of the present invention, the activated multi-source solid waste cementing material is composed of siliceous aluminous cementing components, calcium-iron cementing components, and gypsum-silica composite micro powder in a mass ratio of (5-6):(2-3):1.

[0007] As a preferred embodiment of the present invention, the siliceous alumina cementitious component is obtained by mixing lithium slag powder and electrolytic manganese slag powder at a mass ratio of 1:(0.5-0.8) and then undergoing mechanical-alkali composite activation treatment. Lithium slag is the waste residue after lithium extraction from spodumene or lepidolite, mainly composed of SiO2 and Al2O3, possessing high pozzolanic activity and forming the main body of the siliceous alumina cementitious system. Electrolytic manganese slag is the residue from hydrometallurgical manganese production, rich in SiO2 and SO3, and its sulfate components can activate mineral phase hydration under alkaline activation conditions. The combination of lithium slag and electrolytic manganese slag provides a cementitious framework and sulfate activation, synergistically promoting the cementation reaction.

[0008] As a preferred embodiment of the present invention, the calcium-iron cementitious component is obtained by mixing nickel slag powder and alkali slag at a mass ratio of (1.5-2.5):1 and then undergoing thermal-alkali coupling activation treatment. Nickel slag is a by-product of pyrometallurgical nickel-iron alloy production, mainly containing iron, silicon, and magnesium components, which can generate hydrated calcium silicate gel under alkali activation conditions; alkali slag is the waste residue from the ammonia-soda process for producing soda ash, with the main components being CaCO3, Ca(OH)2, and CaCl2, and a pH>12. Its strong alkalinity provides an alkaline activation environment, and the CaCl2 in the alkali slag helps to accelerate early hydration.

[0009] As a preferred embodiment of the present invention, the gypsum-silica composite micro powder is obtained by mixing desulfurized gypsum and nano-silica at a mass ratio of (1.5-2.5):1 and then subjecting them to synergistic ball milling. The desulfurized gypsum provides SO4. 2- The sulfate-induced effect allows nano-silica fume to generate CSH gel through ultrafine filling and volcanic ash reaction; the synergistic ball milling of the two can solve the problem of nano-silica fume agglomeration, forming a synergistic mechanism of chemical activation and physical compaction.

[0010] As a preferred embodiment of the present invention, the cascade activated shield tunneling excavation soil is prepared by the following method: (1) First, dewater the shield tunneling slag to a moisture content of ≤15%, and then pass the dewatered shield tunneling slag through a 4-mesh sieve, a 40-mesh sieve and a 200-mesh sieve for grading and screening. Particles with a diameter of 0.425mm ≤ 4.75mm are recorded as coarse skeleton components, particles with a diameter of 0.075mm ≤ 0.425mm are recorded as fine filler components, and particles with a diameter of <0.075mm are recorded as fine mud components. (2) Place the fine mud component in a planetary ball mill and ball mill it for 30-120 min at a ball-to-material ratio of (3-8):1 and a speed of 200-600 r / min for mechanical activation; mix the mechanically activated fine mud component with a NaOH solution of 2-6 mol / L at a solid-liquid ratio of 1:(0.3-0.8) and stir at 60-95℃ for 1-4 h for chemical depolymerization activation; calcine the chemically depolymerized and activated fine mud component at 700-900℃ for 0.5-2 h to obtain activated fine mud; (3) Mix the coarse skeleton component, fine filling component and activated fine mud in a mass ratio of (500-800): (400-650): (150-350) to obtain the stepped activated shield tunnel slag.

[0011] As a preferred embodiment of the present invention, the activated shield tunneling wastewater is prepared by the following method: shield tunneling construction wastewater is introduced into a sedimentation tank for natural sedimentation; the supernatant is then subjected to sand filtration to adjust the pH to 7.5-9.5, controlling the suspended solids content to ≤100mg / L; then the treated wastewater is passed through a magnetization device with a magnetic induction intensity of 1000-3000Gs at a flow rate of 1.0-2.0m / s for 10-20 minutes. Magnetization treatment can reduce the size of water molecule clusters, improve the solubility and permeability of water, and promote the hydration reaction of cementitious materials.

[0012] As a preferred embodiment of the present invention, the composite activator is composed of water glass with a modulus of 2.0-3.2, NaOH, and diethanol monoisopropanolamine in a mass ratio of (12-20):(4-10):(0.5-1.0). Water glass provides silicate oligomers and an alkaline environment, while NaOH provides a strongly alkaline environment to promote mineral phase depolymerization. Diethanol monoisopropanolamine promotes mineral phase dissolution and improves slurry fluidity through complexation. Diethanol monoisopropanolamine can simultaneously enhance early and late strength, forming a synergistic effect with calcium formate on "early strength-full-age" performance.

[0013] As a preferred technical solution of the present invention, the layered bimetallic hydroxide is Mg-Al-LDHs or Ca-Al-LDHs. Through interlayer anion exchange and surface adsorption, the residual anionic surfactant in the shield tunnel slag is solidified in its layered structure, reducing its free concentration and passivating its interference with the gelation reaction; the defoamer can further synergistically eliminate residual foam in the system.

[0014] Secondly, the present invention provides a method for preparing the above-mentioned fluidized solidified soil based on shield tunneling slag and multi-source solid waste, comprising the following steps: (1) Dissolve water glass, NaOH, and diethanol monoisopropanolamine in part of the activated shield tunnel wastewater and stir until completely dissolved to obtain a composite activator solution; (2) Add polycarboxylate superplasticizer, hydroxypropyl methylcellulose ether, starch ether, air-entraining agent, defoamer, calcium formate, and sodium aluminate to the remaining activated shield tunnel wastewater and stir until uniformly dispersed to form a functional admixture solution; (3) Dry mix the cascade activated shield tunnel slag and activated multi-source solid waste cementitious material, then add composite activator solution and layered bimetallic hydroxide for wet mixing, and then add functional admixture solution for mixing to obtain a uniform fluid slurry, which is the fluid solidified soil based on shield tunnel slag and multi-source solid waste.

[0015] As a preferred technical solution of the present invention, in step (3), the first stage dry mixing speed is 40-60 r / min and the time is 2-5 min, the second stage wet mixing speed is 80-120 r / min and the time is 2-4 min, and the third stage mixing speed is 50-70 r / min and the time is 3-6 min.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention employs a three-stage activation process—mechanical, chemical, and thermal—to transform fine mud components into active cementitious components, ensuring the fine mud's activity meets the GB / T 2847 standard for pozzolanic materials and improving the overall utilization rate of tunnel boring machine (TBM) slag. Lithium slag provides active Si / Al, electrolytic manganese slag provides natural sulfate activation, nickel slag provides Fe / Si framework support, and alkaline slag provides a strongly alkaline activation environment. Desulfurized gypsum further supplements sulfate activation, and nano-silica fume fills micropores and participates in the pozzolanic reaction. These six solid wastes form a multi-element synergistic cementitious system of "silicon-aluminum donor-sulfate activation-alkaline activation-framework filling-nano-reinforcement." Desulfurized gypsum and nano-silica fume are synergistically ball-milled to form composite micropowder. Desulfurized gypsum provides the sulfate activation effect, while nano-silica fume generates CSH gel through ultrafine filling and pozzolanic reaction. This creates a synergistic mechanism of chemical activation and physical compaction, simultaneously addressing the issue of nano-silica fume agglomeration. By introducing layered bimetallic hydroxides (LDHs), residual anionic surfactants (such as anionic components in foaming agents) in the shield tunnel slag can be solidified into its layered structure through interlayer anion exchange, reducing their free concentration and passivating their interference with the gelation reaction. Simultaneously, the surface physical adsorption of LDHs can help fix some nonionic residues. The chemical solidification effect of LDHs complements the physical defoaming effect of defoamers in functional additives, jointly weakening the negative impact of residual additives in the shield tunnel slag on the gelation system. Shield tunnel wastewater is magnetized and then used as mixing water to alter the water molecule cluster structure, increase water molecule activity, enhance the wetting and reactivity of solid waste particles, and achieve zero wastewater discharge. A three-stage variable-speed mixing process is adopted to balance mixing uniformity, reaction saturation, and slurry stability, avoiding segregation and bleeding. Attached Figure Description

[0017] Figure 1This is a comparison chart of the initial flowability of various embodiments and comparative examples of the present invention.

[0018] Figure 2 This is a comparison chart of the 30-minute flowability retention rates of various embodiments and comparative examples of the present invention.

[0019] Figure 3 This is a comparison chart of the water exudation rates of various embodiments and comparative examples of the present invention.

[0020] Figure 4 The graphs show the growth curves of unconfined compressive strength in various embodiments and comparative examples of the present invention.

[0021] Figure 5 This is a comparison chart of the 28-day shrinkage rates of various embodiments and comparative examples of the present invention.

[0022] Figure 6 This is a comparison diagram of the density difference between the upper and lower parts of each embodiment and comparative example of the present invention at 28 days. Detailed Implementation

[0023] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, embodiments, and comparative examples.

[0024] It should be noted that the raw materials used in the embodiments and comparative examples of this invention can be obtained commercially. The lithium slag powder used is lithium slag powder produced by lithium mica extraction from Jiangxi Jiuling Lithium Industry Co., Ltd., with a specific surface area ≥400m². 2 / kg; the electrolytic manganese slag powder is produced by Hunan Jinxiang Manganese Industry Co., Ltd., using electrolytic manganese slag powder as a byproduct of electrolytic manganese metal production, with a specific surface area ≥350m². 2 / kg; The nickel slag powder is produced by Fujian Qingtuo Nickel Industry Co., Ltd., and is a by-product of nickel-iron alloy smelting. Specific surface area ≥350m² 2 / kg; the alkali residue is a by-product of soda ash production using the ammonia-soda process at Qingdao Alkali Industry Co., Ltd., with a pH ≥ 12; the desulfurization gypsum is desulfurization gypsum powder produced by Suzhou Zhongdian Desulfurization Gypsum Supply Co., Ltd.; the nano silica fume is commercially available industrial-grade nano silica fume with a specific surface area ≥ 18000 m². 2 / kg, SiO2 content ≥99.9%; water glass is commercially available liquid sodium silicate, modulus 2.0-3.2; diethanolmonoisopropanolamine is commercially available industrial grade product, purity ≥99%; polycarboxylate superplasticizer is SP-409 powder polycarboxylate superplasticizer produced by Liaoning Kelong Fine Chemical Co., Ltd., water reduction rate ≥25%; hydroxypropyl methylcellulose ether is commercially available product, viscosity 100,000 mPa·s; starch ether is commercially available carboxymethyl starch ether; air entraining agent is GYQ®-I from Jiangsu Subote New Material Co., Ltd.; defoamer is SBT®-PXP(IV) from Jiangsu Subote New Material Co., Ltd.; calcium formate and sodium aluminate are commercially available industrial grade products; layered bimetallic hydroxides (LDHs) are Mg-Al-LDHs prepared by co-precipitation method. Example

[0025] The tunnel boring machine excavation soil used in this embodiment is the excavation soil generated during the tunnel boring machine construction of a subway section. After dehydration treatment, the moisture content is ≤15%.

[0026] Preparation of cascade activated shield tunneling excavated soil: Dewatered shield tunneling excavated soil was sequentially sieved through a 4-mesh sieve, a 40-mesh sieve, and a 200-mesh sieve to classify and collect coarse skeleton components (0.425mm≤particle size<4.75mm), fine filler components (0.075mm≤particle size<0.425mm), and fine mud components (particle size<0.075mm). The fine mud component was placed in a planetary ball mill and mechanically activated for 60 minutes at a ball-to-material ratio of 5:1 and a rotation speed of 400 r / min. The mechanically activated fine mud component was then mixed with a 4 mol / L NaOH solution at a solid-liquid ratio of 1:0.5 and chemically depolymerized and activated by stirring at 80℃ for 2 hours. The chemically depolymerized and activated fine mud component was then calcined at 800℃ for 1 hour to obtain activated fine mud. By weight, 620 parts of coarse skeleton component, 520 parts of fine filler component, and 360 parts of activated fine mud were mixed evenly to obtain 1500 parts of tiered activated shield tunnel slag.

[0027] Preparation of activated multi-source solid waste cementitious materials: Lithium slag powder and electrolytic manganese slag powder were mixed at a mass ratio of 1:0.6 and ground to a specific surface area ≥400m². 2 / kg, then add 3% NaOH (by weight of total powder) and perform dry grinding and alkali etching for 20 min to obtain a silica-alumina cementitious component; mix nickel slag powder and alkali slag at a mass ratio of 2:1, calcine at 800℃ for 2 h, and grind until the specific surface area is ≥350m². 2 / kg, then surface wet activation was performed with an alkaline solution containing 10wt% NaOH, with a solid-liquid ratio of 1:0.3, and the reaction was stirred for 45 min. After solid-liquid separation and drying, the calcium-iron cementitious component was obtained. Desulfurized gypsum and nano-silica fume were mixed at a mass ratio of 2:1 and put into a ball mill for co-milling for 30 min until the specific surface area of ​​the mixed powder was ≥700m².2 / kg, to obtain gypsum silica fume composite micro powder; according to the weight parts, 385 parts of silica-alumina cementitious component, 175 parts of calcium-iron cementitious component and 70 parts of gypsum silica fume composite micro powder are mixed evenly to obtain 630 parts of activated multi-source solid waste cementitious material.

[0028] Preparation of activated shield tunneling wastewater: The wastewater from shield tunneling construction is introduced into a sedimentation tank for natural sedimentation. The supernatant is then treated by sand filtration, and the pH is adjusted to 8.0, with the suspended solids content controlled to ≤100mg / L. The treated wastewater is then passed through a magnetization device with a magnetic induction intensity of 2000Gs at a flow rate of 1.5m / s for 15min.

[0029] Preparation of composite activator solution: Dissolve 64 parts of water glass with a modulus of 2.6, 30 parts of NaOH, and 3 parts of diethanol monoisopropanolamine in 180 parts of activated shield tunnel wastewater, and stir until completely dissolved to obtain composite activator solution.

[0030] Preparation of functional admixture solution: Add 5 parts of polycarboxylate superplasticizer, 1.2 parts of hydroxypropyl methylcellulose ether, 1.2 parts of starch ether, 1.2 parts of air-entraining agent, 2 parts of defoamer, 5 parts of calcium formate, and 1.2 parts of sodium aluminate to 140 parts of activated shield tunnel wastewater, and stir until uniformly dispersed to form functional admixture solution.

[0031] Preparation of fluidized solidified soil: 1500 parts of stepped activated shield tunnel slag and 630 parts of activated multi-source solid waste cementitious material were dry-mixed at 50 r / min for 3 min. Then, a composite activator solution and 6 parts of layered bimetallic hydroxide were added and wet-mixed at 100 r / min for 3 min. Finally, a functional admixture solution was added and mixed at 60 r / min for 4.5 min to obtain a uniform fluidized slurry. Example

[0032] The tunnel boring machine excavation soil used in this embodiment is the same as that in Embodiment 1.

[0033] Preparation of cascade activated shield tunnel slag: The operation is the same as in Example 1, except that the fine mud component is calcined at 750℃.

[0034] Preparation of activated multi-source solid waste cementitious materials: The mass ratio of lithium slag powder to electrolytic manganese slag powder is 1:0.5, the mass ratio of nickel slag powder to alkaline slag is 1.8:1, and the mass ratio of desulfurized gypsum to nano-silica fume is 1.8:1. The activation process parameters are the same as in Example 1.

[0035] Preparation of activated shield tunnel wastewater, composite activator solution, functional admixture solution and preparation of fluidized solidified soil: The operation is the same as in Example 1. Example

[0036] The tunnel boring machine excavation soil used in this embodiment is the same as that in Embodiment 1.

[0037] Preparation of cascade activated shield tunnel slag: The operation is the same as in Example 1, except that the fine mud component is calcined at 850℃.

[0038] Preparation of activated multi-source solid waste cementitious materials: The mass ratio of lithium slag powder to electrolytic manganese slag powder was 1:0.7, the mass ratio of nickel slag powder to alkaline slag was 2.2:1, and the mass ratio of desulfurized gypsum to nano-silica fume was 2.2:1. The activation process parameters were the same as in Example 1.

[0039] Preparation of activated shield tunnel wastewater, composite activator solution, functional admixture solution and preparation of fluidized solidified soil: The operation is the same as in Example 1.

[0040] Comparative Example 1 The difference between this comparative example and Example 1 is that the fine clay component was not subjected to three-stage activation treatment and was directly mixed with the coarse skeleton component and fine filler component. The other raw material ratios and preparation processes are the same as in Example 1.

[0041] Comparative Example 2 The difference between this comparative example and Example 1 is that the tunnel boring machine wastewater was not treated with magnetization activation, but was directly used as mixing water after only sedimentation and filtration. The other raw material ratios and preparation processes are the same as in Example 1.

[0042] Comparative Example 3 The difference between this comparative example and Example 1 is that layered bimetallic hydroxides (LDHs) were not added. Other raw material ratios and preparation processes are the same as in Example 1.

[0043] Comparative Example 4 The difference between this comparative example and Example 1 is that the composite activator does not contain diethanol monoisopropanolamine, and the composite activator solution is made by dissolving 64 parts of water glass with a modulus of 2.6 and 30 parts of NaOH in 180 parts of activated shield tunneling wastewater, stirring until completely dissolved before use. Other raw material ratios and preparation processes are the same as in Example 1.

[0044] Comparative Example 5 The difference between this comparative example and Example 1 is that diethanol monoisopropanolamine in the composite activator is replaced with Na2CO3, and the composite activator solution is made by dissolving 64 parts of water glass with a modulus of 2.6, 30 parts of NaOH, and 3 parts of Na2CO3 in 180 parts of activated shield tunneling wastewater and stirring until completely dissolved before use. Other raw material ratios and preparation processes are the same as in Example 1.

[0045] Comparative Example 6 The difference between this comparative example and Example 1 is that the solid waste components in the activated multi-source solid waste cementitious material were not subjected to differentiated activation treatment. Specifically, lithium slag powder, electrolytic manganese slag powder, nickel slag powder, and alkaline slag were respectively crushed and ground to a specific surface area ≥350m². 2 / kg, desulfurized gypsum powder is ground to ≥300 mesh, nano silica fume is not treated, and then 241 parts lithium slag powder, 144 parts electrolytic manganese slag powder, 117 parts nickel slag powder, 58 parts alkali slag, 47 parts desulfurized gypsum and 23 parts nano silica fume are directly mixed without mechanical-alkali composite activation, thermal-alkali coupling activation and synergistic ball milling treatment. Other raw material ratios and preparation processes are the same as in Example 1.

[0046] Comparative Example 7 The difference between this comparative example and Example 1 is as follows: The silica-alumina cementitious component uses conventional slag powder and fly ash instead of lithium slag powder and electrolytic manganese slag powder, mixed at a mass ratio of 1:0.6, and subjected to the same mechanical-alkali composite activation treatment. The calcium-iron cementitious component uses steel slag powder and red mud instead of nickel slag powder and alkaline slag, mixed at a mass ratio of 2:1, and subjected to the same thermal-alkali coupling activation treatment. The proportions and total number of the three components of the cementitious material are the same as in Example 1. Other raw material ratios and preparation processes are the same as in Example 1.

[0047] Comparative Example 8 The difference between this comparative example and Example 1 is that the fine mud component in the tiered activated shield tunneling muck is only mechanically activated. Specifically, the fine mud component is placed in a planetary ball mill and milled for 60 minutes at a ball-to-material ratio of 5:1 and a speed of 400 r / min. No chemical depolymerization or thermal activation is performed; instead, it is directly mixed evenly with the coarse skeleton component and the fine filler component to obtain the tiered activated shield tunneling muck. Other raw material ratios and preparation processes are the same as in Example 1.

[0048] Experimental Example 1: Flowability Test The fluidity of the solidified soil slurry in each embodiment and comparative example was tested.

[0049] Test method: Referring to GB / T 2419-2005 "Determination of Flowability of Cement Mortar", a truncated cone mold test was used. Three parallel specimens were prepared for each mix design. The initial flowability and the flowability after standing for 30 minutes were tested respectively, and the arithmetic mean was taken. The results are shown in Table 1. Figure 1 and 2 .

[0050] Table 1. Flowability (mm) of each embodiment and comparative example

[0051] From Table 1 and Figure 1 and Figure 2It can be seen that the initial flowability of Examples 1-3 is between 177 and 193 mm, and the 30-minute flowability retention rate is ≥86.4%, which meets the flowability requirements for pumping construction of fluidized solidified soil (usually requiring an initial flowability ≥160 mm and a 30-minute retention rate ≥80%), indicating that the fluidized solidified soil prepared by this invention has good fluidity and long-term stability. The initial flowability of Comparative Example 6 is only 168 mm, and the 30-minute flowability retention rate is only 79.8%, both of which are the lowest among all samples, and the retention rate is lower than the lower limit of the engineering requirement of 80%. This indicates that the solid waste particles without differentiated activation treatment have irregular morphology and strong water absorption, making them more prone to sedimentation and agglomeration in the slurry, resulting in a significant decrease in flowability and the most serious loss over time. The 30-minute flowability retention rates of Comparative Examples 4 and 5 are 81.8% and 82.1%, respectively, both lower than those of the examples, indicating that the composite activator without diethanolamine has a weak auxiliary effect on particle dispersion, resulting in decreased slurry stability. The initial flowability of Comparative Example 8 was 178 mm, and the flowability retention rate after 30 minutes was 82.0%, both lower than Comparative Example 7 and the other examples. This indicates that the fine mud activated only by mechanical means has low activity and limited improvement in particle surface characteristics. Its effect on improving the flowability and retention of the slurry is not as good as that of traditional solid waste after differentiated activation, and even less so than that of the solid waste combination of the present invention after differentiated activation. The initial flowability of Comparative Example 3 was 189 mm, the highest among all samples, but the flowability retention rate after 30 minutes was lower than that of Examples 1 and 3. This indicates that although the initial flowability of the slurry was improved without the addition of LDHs, the negative impact of residual surfactants on the stability of the slurry gradually became apparent over time.

[0052] Experiment Example 2: Exudation Rate Test The bleeding rate of the fluidized solidified soil slurry in each embodiment and comparative example was tested.

[0053] Test method: Take 90 mL of fresh slurry and place it in a 100 mL graduated cylinder. Seal and let it stand for 2 hours. Measure the volume of the supernatant. Calculate the bleeding rate using the formula: (Supernatant volume / Total slurry volume) × 100%. Prepare 3 parallel specimens for each batch and take the arithmetic mean. The results are shown in Table 2 and [Table data missing]. Figure 3 .

[0054] Table 2. Water seepage rate (%) of each embodiment and comparative example

[0055] From Table 2 and Figure 3It can be seen that the bleeding rate of Examples 1-3 is ≤2.1%, significantly lower than that of Comparative Example 1 (5.6%), Comparative Example 6 (5.0%), and Comparative Example 8 (4.2%). This indicates that the fine mud is transformed into active micropowder after three-stage activation, which fully fills the pores of the particles. At the same time, the surface activity of the differentially activated solid waste particles is enhanced, effectively binding free water and reducing bleeding. The bleeding rate of Comparative Example 6 is 5.0%, indicating that the surface activity of the solid waste fine powder without differential activation is low and the water absorption capacity is poor, so it cannot effectively bind the mixing water. The bleeding rate of Comparative Example 8 is 4.2%, significantly higher than that of the examples, indicating that the fine mud without chemical depolymerization and thermal activation still exists in an inert state and cannot exert the filling and water retention effect of the active micropowder. The bleeding rates of Comparative Examples 4 and 5 are slightly higher than those of the examples, indicating that the composite activator without diethanol monoisopropanolamine has a weaker effect on maintaining the uniformity and stability of the slurry. The bleeding rate of Comparative Example 3 was 2.4%, slightly higher than that of Example 1, indicating that LDHs reduced the interference of residual surfactants on slurry stability by curing them, which is beneficial to reducing bleeding.

[0056] Experimental Example 3: Unconfined Compressive Strength Test Unconfined compressive strength tests were conducted on the fluidized solidified soils of each embodiment and comparative example.

[0057] Test method: Following the "Standard for Geotechnical Testing Methods" (GB / T 50123-2019), specimens were prepared with a size of φ50mm×50mm. Three parallel specimens were prepared for each mix design. Strength was tested after curing for 3 days, 7 days, and 28 days, and the arithmetic mean was taken. The results are shown in Table 3. Figure 4 .

[0058] Table 3 Unconfined compressive strength (MPa) of each embodiment and comparative example

[0059] From Table 3 and Figure 4It can be seen that the 28-day unconfined compressive strength of Examples 1-3 is ≥2.58 MPa, which meets the strength requirements of solidified soil for projects such as backfilling of trenches and roadbed reinforcement (usually requiring 28-day strength ≥2.0 MPa), and the 3-day strength is ≥0.68 MPa, which meets the early bearing requirements (usually requiring 3-day strength ≥0.5 MPa). This indicates that the fluidized solidified soil prepared by this invention has both good early and late strength. The 28-day strength of Comparative Example 1 is only 1.58 MPa, which is 58% of that of Example 1, indicating that the fine mud cannot play a cementing role without activation treatment, which seriously affects the strength of the solidified soil. The 28-day strength of Comparative Example 6 is 1.72 MPa, which is 63% of that of Example 1, indicating that the solid waste without differential activation has extremely low activity and cannot effectively participate in the cementation reaction, indicating that differential activation is the key means to release the cementation potential of solid waste. The 28-day strength of Comparative Example 8 was 1.85 MPa, which was 68% of that of Example 1. This indicates that mechanical activation alone is insufficient in releasing the activity of the fine mud, and that chemical depolymerization activation and thermal activation play a crucial role in fully releasing the gelling activity of the fine mud. The 28-day strengths of Comparative Examples 4 and 5 were 2.02 MPa and 2.10 MPa, respectively, which were 75% and 77% of those of Example 1. This indicates that diethanolamine monoisopropanolamine is the key component of the composite activator in improving strength. The addition of Na2CO3 to Comparative Example 5 only increased the strength by about 4%, which is a limited increase, indicating that carbonates cannot achieve an activation effect comparable to that of organic amines. The 28-day strength of Comparative Example 7 was 2.25 MPa, which was 83% of that of Example 1. This indicates that the combination of lithium slag, electrolytic manganese slag, nickel slag, and alkaline slag selected in this invention is superior to the combination of traditional slag, fly ash, steel slag, and red mud under the same activation conditions. Among them, lithium slag provides active silicon-aluminum components, electrolytic manganese slag provides natural sulfate activation, nickel slag provides skeletal support, and alkaline slag provides an alkaline activation environment. The four components complement each other and form a more complete synergistic mechanism of cementation reaction than the traditional combination.

[0060] Experiment Example 4: Drying Shrinkage Test Drying shrinkage tests were conducted on the fluidized solidified soils of each embodiment and comparative example.

[0061] Test method: Refer to the "Test Method for Drying Shrinkage of Cement Mortar". Specimen size is 40mm×40mm×160mm. The 28-day drying shrinkage rate is tested. Three parallel specimens are prepared for each mix design, and the arithmetic mean is taken. The results are shown in Table 4. Figure 5 .

[0062] Table 4. 28-day shrinkage rate (%) of each embodiment and comparative example

[0063] From Table 4 and Figure 5It can be seen that the 28-day shrinkage rate of Examples 1-3 is ≤0.042%, significantly lower than that of Comparative Example 1 (0.071%), Comparative Example 6 (0.064%), and Comparative Example 8 (0.058%), indicating that the gelling products formed after fine mud activation fill the pores, reduce capillary shrinkage stress, and effectively inhibit drying shrinkage. The 28-day shrinkage rate of Comparative Example 6 is 0.064%, significantly higher than that of the examples, indicating that the surface of unactivated solid waste particles lacks reactivity, the amount of hydration products generated is small, the porosity is large, and the shrinkage stress is concentrated. The 28-day shrinkage rate of Comparative Example 8 is 0.058%, significantly higher than that of the examples, indicating that the fine mud that has only undergone mechanical activation cannot fully participate in the gelling reaction, the pores are not fully filled, resulting in increased shrinkage. The shrinkage rates of Comparative Examples 4 and 5 were 0.052% and 0.049%, respectively, both higher than those of the embodiments. This indicates that the amount of hydration products generated is reduced in the activator system without diethanol monoisopropanolamine, resulting in insufficient microstructural densification and increased shrinkage. The shrinkage rate of Comparative Example 7 was 0.044%, slightly higher than that of the embodiments, but still significantly lower than that of Comparative Examples 1, 6, and 8. This indicates that the traditional solid waste combination still possesses a certain degree of volume stability after activation, but its overall effect is weaker than that of the hexa-element solid waste combination of the present invention.

[0064] Experimental Example 5: Density Difference Test of Solidified Soil The density difference test was performed on the fluidized solidified soil of each embodiment and comparative example to evaluate its anti-settlement performance.

[0065] Test method: After curing the solidified soil for 28 days, it was cut into two equal parts, and the wet density of each part was measured. The percentage difference in density between the upper and lower parts was calculated as follows: Density difference = (Upper section density - Lower section density) / Average density × 100%, reflecting the degree of settlement stratification. Three parallel specimens were prepared for each mix, and the arithmetic mean was taken. The results are shown in Table 5. Figure 6 .

[0066] Table 5. Density difference (%) between the upper and lower limits of each embodiment and comparative example at 28 days.

[0067] From Table 5 and Figure 6It can be seen that the density difference between the upper and lower parts of Examples 1-3 is ≤2.5%, significantly lower than that of Comparative Examples 6, 1, and 8, indicating that activated fine mud and differentially activated solid waste particles can form a uniform and stable suspension system in the slurry, effectively inhibiting particle sedimentation and stratification. Comparative Example 6 has the largest density difference, indicating that the surface of undifferentiated solid waste particles lacks gelling reactivity and cannot form a stable network structure in the slurry, resulting in severe particle sedimentation and a significant difference in density between the upper and lower parts of the solidified body. The density difference between the upper and lower parts of Comparative Example 8 is 4.1%, indicating that the fine mud, which is only mechanically activated, still tends to agglomerate and settle in the slurry, failing to form a uniform and stable suspension system. The density differences between the upper and lower parts of Comparative Examples 4 and 5 are 3.5% and 3.2%, respectively, both higher than those of the examples, indicating that the composite activator without diethanol monoisopropanolamine has a weaker effect on maintaining the suspension stability of the slurry. The density difference between the upper and lower parts of Comparative Example 7 was 2.8%, which was slightly higher than that of the other examples, indicating that the traditional solid waste combination still has a certain anti-settling performance after activation, but its overall uniformity is weaker than that of the six-element solid waste combination of the present invention.

[0068] The above results show that the fluidized solidified soil based on shield tunneling slag and multi-source solid waste provided by the present invention has excellent comprehensive performance in terms of fluidity, water retention, mechanical strength, volume stability and uniformity.

[0069] Although specific technical solutions of the present invention have been described in detail through embodiments, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the direction of the present invention or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A fluidized solidified soil based on the synergistic effect of shield tunneling excavation soil and multi-source solid waste, characterized in that... It includes the following components by weight: 1200-1700 parts of cascade activated shield tunnel slag, 350-650 parts of activated multi-source solid waste cementitious material, 250-380 parts of activated shield tunnel wastewater, 80-160 parts of composite activator, 2-8 parts of polycarboxylate superplasticizer, 0.5-2 parts of hydroxypropyl methylcellulose ether, 0.5-2 parts of starch ether, 0.5-2 parts of air-entraining agent, 1-3 parts of defoamer, 2-8 parts of calcium formate, 0.5-2 parts of sodium aluminate, and 3-10 parts of layered bimetallic hydroxide; The activated multi-source solid waste cementitious material is composed of aluminosilicate cementitious components, calcium-iron cementitious components, and gypsum-silica composite micro powder in a mass ratio of (5-6):(2-3):

1. The aluminosilicate cementitious components are obtained by mechanical-alkali composite activation treatment after mixing lithium slag powder and electrolytic manganese slag powder in a mass ratio of 1:(0.5-0.8). The calcium-iron cementitious components are obtained by thermal-alkali coupling activation treatment after mixing nickel slag powder and alkali slag in a mass ratio of (1.5-2.5):

1. The gypsum-silica composite micro powder is obtained by synergistic ball milling after mixing desulfurized gypsum and nano-silica in a mass ratio of (1.5-2.5):

1.

2. The fluidized solidified soil based on the synergistic effect of shield tunneling slag and multi-source solid waste as described in claim 1, characterized in that, The preparation method of the cascade activated shield tunnel excavation soil is as follows: (1) First, dewater the shield tunneling slag to a moisture content of ≤15%, and then pass the dewatered shield tunneling slag through a 4-mesh sieve, a 40-mesh sieve and a 200-mesh sieve for grading and screening. Particles with a diameter of 0.425mm ≤ 4.75mm are recorded as coarse skeleton components, particles with a diameter of 0.075mm ≤ 0.425mm are recorded as fine filler components, and particles with a diameter of <0.075mm are recorded as fine mud components. (2) Place the fine mud component in a planetary ball mill and ball mill it for 30-120 min at a ball-to-material ratio of (3-8):1 and a speed of 200-600 r / min for mechanical activation; mix the mechanically activated fine mud component with a NaOH solution of 2-6 mol / L at a solid-liquid ratio of 1:(0.3-0.8) and stir at 60-95℃ for 1-4 h for chemical depolymerization activation; calcine the chemically depolymerized and activated fine mud component at 700-900℃ for 0.5-2 h to obtain activated fine mud; (3) Mix the coarse skeleton component, fine filling component and activated fine mud in a mass ratio of (500-800):(400-650):(150-350) to obtain the stepped activated shield tunnel slag.

3. The fluidized solidified soil based on the synergistic effect of shield tunneling slag and multi-source solid waste as described in claim 1, characterized in that, The mechanical-alkali composite activation treatment of the silica-alumina cementitious component specifically involves mixing lithium slag powder and electrolytic manganese slag powder and then grinding them to a specific surface area ≥ 400 m². 2 / kg, then add 2-5% NaOH (by weight of total powder) and perform dry grinding and alkali etching for 10-30 minutes.

4. The fluidized solidified soil based on the synergistic effect of shield tunneling slag and multi-source solid waste as described in claim 1, characterized in that, The specific process for the thermal-alkali coupled activation treatment of the calcium-iron cementitious component is as follows: nickel slag powder and alkali slag are mixed and calcined at 700-900℃ for 1.5-2.5 hours, and then ground to a specific surface area ≥350m². 2 / kg, then surface wet activation with alkaline solution containing 10wt% NaOH, solid-liquid ratio 1:0.3, stirring reaction for 30-60min, after solid-liquid separation and drying for later use.

5. The fluidized solidified soil based on the synergistic effect of shield tunneling slag and multi-source solid waste as described in claim 1, characterized in that, The synergistic ball milling treatment of the gypsum-silica composite micro powder specifically involves mixing desulfurized gypsum and nano-silica, then grinding them in a ball mill for 20-40 minutes. The resulting powder has a specific surface area ≥700 m². 2 / kg.

6. The fluidized solidified soil based on the synergistic effect of shield tunneling excavation and multi-source solid waste as described in claim 1, characterized in that: The composite activator is composed of water glass with a modulus of 2.0-3.2, NaOH, and diethanol monoisopropanolamine in a mass ratio of (12-20):(4-10):(0.5-1.0).

7. The fluidized solidified soil based on shield tunneling excavation and multi-source solid waste as described in claim 1, characterized in that: The activated shield tunneling wastewater is obtained by introducing shield tunneling construction wastewater into a sedimentation tank for natural sedimentation, taking the supernatant for sand filtration, adjusting the pH to 7.5-9.5, and controlling the suspended solids content to ≤100mg / L; then the treated wastewater is passed through a magnetization device with a magnetic induction intensity of 1000-3000Gs at a flow rate of 1.0-2.0m / s for 10-20min.

8. The fluidized solidified soil based on the synergistic effect of shield tunneling slag and multi-source solid waste as described in claim 1, characterized in that, The layered bimetallic hydroxide is Mg-Al-LDHs or Ca-Al-LDHs.

9. A method for preparing fluidized solidified soil based on shield tunneling slag and multi-source solid waste as described in any one of claims 1-8, characterized in that, Includes the following steps: (1) Dissolve water glass, NaOH, and diethanol monoisopropanolamine in part of the activated shield tunnel wastewater and stir until completely dissolved to obtain a composite activator solution; (2) Add polycarboxylate superplasticizer, hydroxypropyl methylcellulose ether, starch ether, air-entraining agent, defoamer, calcium formate, and sodium aluminate to the remaining activated shield tunnel wastewater and stir until uniformly dispersed to form a functional admixture solution; (3) Dry mix the cascade activated shield tunnel slag and activated multi-source solid waste cementitious material, then add composite activator solution and layered bimetallic hydroxide for wet mixing, and then add functional admixture solution for mixing to obtain a uniform fluid slurry, which is the fluid solidified soil based on shield tunnel slag and multi-source solid waste.

10. The preparation method according to claim 9, characterized in that: In step (3), the first stage of dry mixing is 40-60 r / min and the time is 2-5 min, the second stage of wet mixing is 80-120 r / min and the time is 2-4 min, and the third stage of mixing is 50-70 r / min and 3-6 min.

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