Multi-source solid waste-based foamed fluidized solidified soil preparation and quality control method

Abstract

The present application belongs to the technical field of geotechnical engineering and solid waste resource utilization, and particularly relates to a method for preparing and quality controlling multi-source solid waste-based foamed fluidized solidified soil. The present application uses engineering waste mud and engineering waste slag to prepare a mud base with a fixed water content, and uses industrial solid waste and biomass solid waste to prepare a multi-source solid waste-based composite solidifying agent to partially replace cement. After the mud base and the multi-source solid waste-based composite solidifying agent are mixed according to the water-cement ratio and the cement-soil ratio, the fluidized solidified soil is obtained, and then bubbles prepared by a pre-foaming method are introduced to obtain foamed fluidized solidified soil. The present application integrates the fluidity of the slurry and the strength of the hardened body into the same parameter system, changes the traditional design mode which relies on empirical trial, and introduces a strength prediction model and an inversion formula, thereby improving the efficiency of the mix proportion design and the reproducibility of the results.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering and solid waste resource utilization technology, specifically relating to a method for preparing and quality controlling multi-source solid waste-based foamed fluidized solidified soil. Background Technology

[0002] Fluidized solidified soil is a slurry-like filling material made by mixing soil, solidifying agent, and water in a designed ratio. It is widely used in backfilling projects such as foundation pits, pipeline trenches, and roadbed abutments. The soil can be selected from construction waste, silt, etc. Currently, the solidifying agent for conventional fluidized solidified soil is mainly ordinary silicate cement. This results in high cement consumption, high material costs, and high resource consumption and carbon emissions during cement production, which is incompatible with the development requirements of green and low-carbon transformation in engineering construction. my country generates a huge amount of industrial solid waste and biomass solid waste, with high accumulation and limited comprehensive utilization. Long-term accumulation not only occupies land resources but also poses a pollution risk to the surrounding environment through leachate infiltration and dust diffusion. Utilizing industrial solid waste and biomass solid waste to prepare composite solidifying agents, partially replacing cement in fluidized solidified soil, is an effective technical path to reduce cement consumption, dispose of solid waste, and achieve waste-to-waste treatment.

[0003] The practical application of solid waste-based composite solidifiers in fluidized solidified soil still faces several challenges. The moisture content of engineering waste slurry fluctuates drastically due to construction conditions. Direct solidification of slurry with high moisture content leads to excessive dilution of the solidifier, resulting in incomplete hydration, slow strength development, and significant dispersion. On-site adjustment of slurry moisture content relies heavily on experience, lacking a method to uniformly control slurry in different initial states to the target benchmark, making it difficult to stabilize the solidification effect. Solid waste-based solidifiers have diverse components and significant activity differences, and their strength variation with water-cement ratio differs significantly from that of pure cement systems. Using the trial mixing experience of pure cement systems to determine the mix proportion results in low design efficiency and poor reproducibility. Introducing air bubbles into fluidized solidified soil is a feasible means to reduce filling density and achieve lightweighting; however, the active substances in the solid waste components may interfere with the stability of the air bubbles, leading to increased defoaming, deviation of wet density from the design value, and a lack of synergy between the foaming process and the solid waste-based solidifier system. Summary of the Invention

[0004] To address the problems of high cement consumption, low solid waste utilization, and lack of systematic methods for mix design and foaming processes in existing fluidized bed solidified soil, this invention provides a method for preparing and controlling the quality of multi-source solid waste-based foamed fluidized bed solidified soil. This invention utilizes engineering waste mud and engineering waste slag to prepare a mud base material with a fixed moisture content. A multi-source solid waste-based composite solidifying agent is prepared using industrial solid waste and biomass solid waste to partially replace cement. The dosage relationship between the mud base material with the fixed moisture content and the multi-source solid waste-based composite solidifying agent is determined by the dual parameters of water-cement ratio and lime-soil ratio to obtain fluidized bed solidified soil. Then, air bubbles prepared by a pre-foaming method are introduced to obtain foamed fluidized bed solidified soil. Moisture content control, mix design determination, and air bubble dosage adjustment are all performed quantitatively in each step.

[0005] Technical solution: A foamed fluidized solidified soil based on multi-source solid waste, comprising, by mass percentage, 78%–93% slurry base material with fixed moisture content, 4%–12% multi-source solid waste-based composite solidifying agent, and 1%–10% water; the dosage of water-reducing agent and water-retaining agent is based on the total mass of the multi-source solid waste-based composite solidifying agent, with the water-reducing agent accounting for 0.5%–1.0% of the total mass of the multi-source solid waste-based composite solidifying agent and the water-retaining agent accounting for 0.1%–0.3% of the total mass of the multi-source solid waste-based composite solidifying agent; the bubble content is 1%–5% based on the percentage of bubble volume to dry soil mass.

[0006] Furthermore, the fixed moisture content mud base material is prepared by applying it to a mass of... M 1. Initial moisture content is w 1. The mass of high moisture content engineering waste mud mixed in is X Moisture content is w The waste soil from project 2 was mixed and prepared. After preparation, samples were taken to check the moisture content, and the deviation was controlled within the target moisture content. w t Within ±2% (absolute value).

[0007] Furthermore, the quality of the mixed construction waste soil... X The formula is determined as follows: All moisture contents mentioned above are wet basis moisture contents.

[0008] Furthermore, the initial moisture content of the engineering waste mud... w 1. Take the average value of multiple samples taken on site, and the target moisture content. w t The optimal moisture content value is obtained by referring to the soil liquid limit or compaction test.

[0009] Furthermore, the multi-source solid waste-based composite curing agent, by mass percentage, consists of 40%–55% cement, 30%–45% finely ground blast furnace slag powder, and 10%–18% biomass incineration ash.

[0010] Furthermore, the cement is ordinary Portland cement of grade PO 42.5 or above, which hydrates to form hydrated calcium silicate gel and calcium hydroxide, providing early cementitious properties for the curing system.

[0011] Furthermore, the aforementioned finely ground blast furnace slag powder is made from molten slag discharged during the blast furnace ironmaking process in the iron and steel industry, through water quenching, drying, and grinding, with a particle size of no more than 30 μm and a specific surface area of ​​no less than 400 m². 2 / kg, the main components are calcium oxide, silicon dioxide and aluminum oxide. The slag powder undergoes a secondary hydration reaction under alkaline conditions initiated by cement hydration, generating cementitious products such as hydrated calcium silicate and hydrated calcium aluminosilicate, which provide later-stage strength for the multi-source solid waste-based composite solidifying agent.

[0012] Furthermore, the biomass incineration ash is made from brewer's grains or vinegar residue produced in the brewing industry. After drying and pulverizing, it is incinerated at 600℃~800℃ under aerobic conditions for 2h~4h, and then ground until the residue on a 45μm square-hole sieve is no more than 30%. Its main component is amorphous silica. The incineration ash exhibits pozzolanic activity, can consume calcium hydroxide produced during cement hydration, and improve the chemical stability of multi-source solid waste-based composite solidifying agents.

[0013] Furthermore, the preparation process of the multi-source solid waste-based composite curing agent is as follows: ordinary silicate cement, finely ground blast furnace slag powder and biomass incineration ash are weighed according to the mass percentage, and then put into a dry powder mixer in sequence. The mixture is dry-mixed for no less than 3 minutes until the material has a uniform color. After discharge, the material is sieved to remove lumps, and the multi-source solid waste-based composite curing agent is obtained.

[0014] Furthermore, the water-reducing agent is a polycarboxylate-based water-reducing agent, and the dosage is 0.5% to 1.0% of the total mass of the multi-source solid waste-based composite curing agent, used to reduce the water-cement ratio and improve the fluidity of the slurry.

[0015] Furthermore, the water-retaining agent is hydroxypropyl methylcellulose, and the dosage is 0.1% to 0.3% of the total mass of the multi-source solid waste-based composite curing agent, used to reduce slurry bleeding and improve homogeneity.

[0016] Furthermore, the bubbles are prepared using a pre-foaming method, and the foaming agent used is a composite foaming agent composed of a foaming component and a foam-stabilizing component. The foaming component is mainly composed of anionic surfactants, and the foam-stabilizing component is mainly composed of alkylolamides and silicone polyethers. In use, the foaming component and the foam-stabilizing component are first mixed at a mass ratio of 1:4, then diluted with 80 times their mass of water to form a foaming solution. Compressed air is then introduced through a physical foaming machine to create pre-formed bubbles. The foam density of the pre-formed bubbles is... 40-50 kg / m 3 The settling distance in 1 hour should not exceed 5 mm, and the water bleeding rate in 1 hour should not exceed 10%.

[0017] Furthermore, after the foam quality of the bubbles is qualified, they are added to the mixture according to the designed bubble rate. The amount of bubbles added is calculated as a percentage of the bubble volume to the dry soil mass, with a range of 1% to 5%, and the optimal amount is 2%.

[0018] Furthermore, the water-cement ratio of the foamed fluidized solidified soil based on multi-source solid waste is... W / C Compared to ash soil C / S The determination process, namely the two-parameter mix design method of water-cement ratio and lime-soil ratio, is as follows: S1: Determine the theoretical initial water-cement ratio based on the target moisture content. Let the dry soil mass in the mud slurry base material be... S The quality of the multi-source solid waste-based composite curing agent is C The target moisture content is w t The ratio of ash to soil is C / S The lime-soil ratio is determined by the following formula:

[0019] When the target moisture content w t The total amount of water required to reach the target moisture content, calculated based on the wet substrate mass moisture content, i.e., the proportion of water mass to the total mass of soil and water. W t for:

[0020] Therefore, the theoretical initial water-cement ratio is:

[0021] In the formula, W This represents the total water consumption. C For the quality of multi-source solid waste-based composite curing agents, S For dry soil quality, w t For the target moisture content, C / S The ratio of ash to soil.

[0022] In the initial design phase, priority should be given to the lime-soil ratio. C / S Set 10% as the baseline value and calculate the theoretical water-cement ratio according to the above formula. If the water content of the slurry base material is insufficient to reach the target moisture content, add water according to the difference; if the water content of the slurry base material is already higher than the target water content, do not add water, and correct the water content by increasing the dosage of multi-source solid waste-based composite solidifying agent, adding dry solid waste materials, or adjusting the moisture content of the slurry base material.

[0023] S2: Prepare trial mixtures according to the initial mixing ratio. According to the theoretical water-cement ratio determined by S1 W / C Compared to ash soil C / S Weigh out the mud base material, multi-source solid waste-based composite curing agent, water and appropriate amount of additives (water-reducing agent, water-retaining agent), and mix them thoroughly to prepare a fluidized solidified soil test mixture.

[0024] During the mixing process, the multi-source solid waste-based composite curing agent should be uniformly dispersed to avoid local agglomeration, segregation, or significant bleeding. After trial mixing, a flowability test should be conducted immediately to provide a basis for subsequent water-cement ratio adjustments.

[0025] S3: Flowability test and water-cement ratio feedback adjustment The fluidity of the mixture prepared by S2 was determined by a fluidity test. L And record the time T required to extend to 200mm. 200 The applicable range for construction of fluidized solidified soil is defined as a fluidity of 160–200 mm.

[0026] When fluidity L If the thickness is less than 160mm, it indicates insufficient fluidity of the mixture; therefore, the water-cement ratio should be increased first. W / C If simply increasing the water-cement ratio leads to insufficient strength reserve, the lime-soil ratio can be appropriately reduced. C / S Or optimize the dosage of admixtures.

[0027] When fluidity L If the thickness exceeds 200 mm, or if the mixture exhibits obvious bleeding or segregation, it indicates that the mixture has excessive fluidity or insufficient stability, and the water-cement ratio should be reduced as a priority. W / C If segregation is still difficult to suppress after reducing the water-cement ratio, the lime-soil ratio can be appropriately increased. C / S This is to enhance the cohesiveness and structural stability of the slurry.

[0028] Each time the water-cement ratio is adjusted, W / C The adjustment range should be controlled within 0.1 to 0.3, and the lime-soil ratio should be... C / S The adjustment range should be controlled within 1% to 3%. After each adjustment, the mixture should be prepared again and the flowability test should be repeated until the flowability meets the requirement of 160 to 200 mm and there is no obvious bleeding or segregation.

[0029] S4: Strength Testing and Strength Prediction Model Establishment Once the flowability of the mixture met the requirements, cylindrical specimens were prepared using this mix proportion and cured under standard curing conditions to the designed age. Unconfined compressive strength tests were then conducted, and the average value of the strength test results from three parallel specimens was taken as the measured strength of this mix proportion. .

[0030] To establish the correlation between water-cement ratio, soil-cement ratio, and strength, the following strength prediction model is introduced:

[0031] In the formula, For unconfined compressive strength, A The strength coefficient is related to the type of curing agent, soil properties, and curing conditions. B The water-cement ratio is the indices that affect the water-cement ratio. n This is the index affecting the soil-cement ratio.

[0032] When the ash-soil ratio C / S When the equation remains constant, the above formula can be simplified to:

[0033] In the formula, A and B The strength data can be obtained by fitting the measured strength data under different water-cement ratios using the least squares method.

[0034] S5: Inversion correction of water-cement ratio based on strength requirements measured strength Strength required by design Compare. If ≥ If the fluidity of the mixture still meets the requirement of 160-200 mm, then this mix proportion can be used as a candidate mix proportion.

[0035] like < This indicates that the current mix proportion strength is insufficient, and the target water-cement ratio to meet the design strength requirements should be obtained by inversion from the strength prediction model. For the strength model under a fixed cement-soil ratio, the inversion formula is:

[0036] In the formula, Strength required by design specifications.

[0037] After reducing the water-cement ratio based on the inversion results, flowability and strength tests should be repeated to determine whether the construction flowability and design strength requirements are met simultaneously.

[0038] S6: Progressive Optimization of Lime-Soil Ratio and Determination of Final Mix Proportion When the strength requirements can be met by reducing the water-cement ratio, and the fluidity is still within the range of 160-200mm, the modified water-cement ratio is adopted as the final design value.

[0039] While reducing the water-cement ratio increases strength, insufficient fluidity (below 160mm) leads to inadequate workability during construction. This indicates that simply adjusting the water-cement ratio is insufficient to simultaneously meet both fluidity and strength requirements. In such cases, the cement-soil ratio should be increased gradually in increments of 2%. C / S And repeat S1 to S5 at each lime-soil ratio until the fluidity, stability and strength of the mixture meet the design requirements.

[0040] Finally, the mix proportion that meets the following conditions is selected as the design mix proportion: 160mm≤ L ≤200mm ≥

[0041] Furthermore, the mixture showed no obvious bleeding or segregation. The corresponding water-cement ratio at this point is... W / C , Lime-soil ratio C / S The added water volume and the dosage of the multi-source solid waste-based composite solidifying agent are the final mix proportion parameters of the multi-source solid waste foamed fluidized solidified soil; the corresponding fluidity value of the mixture is recorded as the design reference fluidity. For use in evaluating construction quality.

[0042] Furthermore, a process for preparing foamed fluidized solidified soil based on multi-source solid waste includes the following steps: Step 1: Calculate the amount of engineering waste soil to be added according to the formula for determining the mixing quality of engineering waste soil. Add the engineering waste soil to the engineering waste mud, stir and mix, take a sample to check the moisture content, adjust it to the target moisture content, and obtain mud base material with fixed moisture content.

[0043] Step 2: Weigh out cement, finely ground blast furnace slag powder and biomass incineration ash according to the stated mass percentages, and dry mix them evenly to obtain the multi-source solid waste-based composite curing agent.

[0044] Step 3: Determine the water-cement ratio and lime-soil ratio according to the dual-parameter mix design method, calculate the total water requirement, and determine the additional water to be added after deducting the water contained in the mud base material. Weigh the mud base material, multi-source solid waste composite solidifying agent, water and admixtures, and stir to prepare a fluidized solidified soil mixture.

[0045] Step 4: Add the pre-made air bubbles to the mixture obtained in Step 3 according to the stated air bubble ratio, and stir slowly until the air bubbles are evenly distributed. Test the wet density; the measured value should not deviate from the design value by more than 5%. If it fails to meet the requirements, adjust the air bubble content in increments of 0.2% to 0.5%, or adjust the baseline water-cement ratio and / or lime-soil ratio, repeating the adjustments until the design requirements are met, thus obtaining the foamed fluidized solidified soil.

[0046] Furthermore, a method for quality control of multi-source solid waste-based foamed fluidized bed solidified soil includes the following steps: Step 1: During construction, samples are taken at one or more locations, including the mixing outlet, pump outlet, and pouring surface, to collect on-site flowability data of the foamed fluidized solidified soil. Cylindrical specimens were prepared by sampling at the pouring site, and after standard curing for 28 days, unconfined compressive strength tests were conducted to obtain strength test data. After construction, settlement monitoring points are set up at equal intervals on the surface of the backfill, preferably along the longitudinal centerline, longitudinal survey line, or transverse survey line of the backfill, to collect settlement deformation data. and the distance between adjacent monitoring points .

[0047] Step 2: Calculate the flowability compatibility index based on the on-site flowability test data. This index is used to characterize the deviation of the on-site flowability of solidified fluid from the design target value, as well as the fluctuation of flowability between different test batches. Its calculation formula is as follows:

[0048] In the formula, For the first i The flowability test value (mm) at the site; The design reference flowability (mm) is ultimately determined by the water-cement ratio and lime-soil ratio determination process S6. The allowable flowability deviation (mm) is generally taken as 20 to 30 mm; n The number of flowability tests; The smaller the value, the closer the flow rate is to the design target and the smaller the fluctuation, indicating better fill adaptability.

[0049] Step 3: Calculate the strength reliability index based on the unconfined compressive strength test data. This index is used to characterize the degree to which the unconfined compressive strength of hardened fluidized solidified soil meets the design strength, as well as the degree of dispersion of strength results among different specimens. Its calculation formula is as follows:

[0050] In the formula, For the first jUnconfined compressive strength (MPa) of the group of specimens; The theoretical predicted strength (MPa) is taken from the strength prediction model calculated based on the final mix proportion. In the formula, A The strength coefficient is related to the type of curing agent, soil properties, and curing conditions. B The water-cement ratio is the indices that affect the water-cement ratio. W / C The final mix proportion and water-cement ratio determined for S6; m The number of strength test specimen groups; The intensity characteristic value is calculated using the following formula: ; The strength guarantee correction factor is set at 1.28 to 1.65 (corresponding to a 90% to 95% guarantee rate). The smaller the value, the higher the strength meets the standard and the smaller the dispersion, indicating better strength reliability.

[0051] Step 4: Calculate the settlement deformation stability index based on the settlement deformation monitoring data. This index is used to characterize the maximum cumulative settlement after the completion of fluidized solidified soil construction and the degree of uneven settlement between adjacent measuring points. Its calculation formula is:

[0052] In the formula, The absolute value (mm) of the maximum cumulative settlement among all monitoring points; The maximum allowable settlement value (mm) is generally taken as 5 to 15 mm; The maximum settlement gradient between adjacent monitoring points; For the first i The and the first j The distance between monitoring points; The settlement gradient limit is generally set between 0.002 and 0.005. The smaller the value, the smaller the overall settlement and the less uneven deformation.

[0053] Step 5: Based on the fluid filling compatibility index, strength reliability index, and settlement deformation stability index, establish a comprehensive construction quality risk index. R The calculation formula is as follows:

[0054] In the formula, This is the index coupling amplification factor, reflecting the amplification effect of the mutual influence between the three indicators on the overall quality. It is generally taken as 0.20 to 0.50, and 0.40 to 0.50 for important projects. To prevent extremely small positive numbers with a denominator of zero, we take 0.001. RThe smaller the value, the lower the risk of construction quality issues.

[0055] Step Six: Based on the comprehensive construction quality risk index R Calculate the overall construction quality score Q The construction quality of fluidized solidified soil is graded and judged, and acceptance, verification, re-grouting, reinforcement or rework measures are determined based on the judgment results. Q The calculation formula is:

[0056] Q The larger the value, the better the construction quality. The quality grade determination is shown in the table below: Table 1 Quality Grade Determination Table

[0057] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention establishes a self-adaptive control model for mud moisture content based on the law of conservation of mass. By quantitatively calculating the amount of slag added, the engineering waste mud with different initial moisture contents is uniformly controlled to the target benchmark. This solves the problem of unstable solidification effect and large strength dispersion caused by the fluctuation of mud moisture content, and provides a homogeneous and stable base material for subsequent mix design.

[0058] (2) This invention uses industrial solid waste and biomass solid waste as raw materials to prepare multi-source solid waste-based composite solidifying agent, which partially replaces cement for fluid solidified soil. While ensuring the strength of the project, it reduces the amount of cement used and material costs, reduces the resource consumption and carbon emissions in the cement production process, and provides a large-scale disposal method for multi-source solid waste.

[0059] (3) This invention constructs a mix design framework with water-cement ratio and lime-soil ratio as dual core parameters. Through mutual constraint and synergistic regulation of the two, the fluidity of the slurry and the strength of the hardened body are incorporated into the same parameter system, which changes the traditional design mode that relies on experience trial mixing.

[0060] (4) This invention introduces a strength prediction model and inversion formula, and establishes a graded progressive design process from initial mix proportion determination to flowability feedback, strength testing, inversion correction and then to the progressive lime-soil ratio, which improves the efficiency of mix proportion design and the reproducibility of results.

[0061] (5) This invention clarifies three foam quality control indicators: foam density, settling distance and bleeding rate, establishes a quantitative relationship between bubble rate and wet density, uses measured wet density as feedback indicator to adjust bubble content in a gradient, solves the problem of solid waste components interfering with bubble stability, realizes the synergy between foaming process and solid waste-based solidifying agent system, and the lightweight effect is controllable.

[0062] (6) The construction quality control method of this invention is deeply integrated with the material preparation system. The evaluation criteria are directly derived from the output values ​​of the mix design stage, rather than externally introduced general empirical indicators. The evaluation criteria are determined according to the component ratio and strength characteristics of the multi-source solid waste-based composite curing agent used, which can truly reflect the performance deviation of the specific material system during the construction stage and avoid misjudgments caused by general evaluation methods ignoring the material's own characteristics. When the mix ratio parameters change, the evaluation criteria are adjusted synchronously, so that the quality judgment conclusion always matches the actual performance of the material, providing a more reliable basis for the acceptance of project quality. Attached Figure Description

[0063] Figure 1 This is a flowchart illustrating the overall process of preparing and controlling the quality of foamed fluidized bed solidified soil from multi-source solid waste in this embodiment. Figure 2 This is a schematic diagram illustrating the preparation of mud base material with fixed moisture content and the self-adaptive control of moisture content in this embodiment; Figure 3 This is a schematic diagram illustrating the preparation of the multi-source solid waste-based composite curing agent in this embodiment; Figure 4 This is a flowchart illustrating the determination of the two-parameter mix proportions of water-cement ratio and lime-soil ratio in this embodiment; Figure 5 This is a schematic diagram illustrating the preparation of pre-formed bubbles in this embodiment; Figure 6 This is a schematic diagram of the pre-formed bubble incorporation and wet density feedback control in this embodiment; Figure 7 This is a schematic diagram of the on-site construction and monitoring sampling layout of the foamed fluidized solidified soil in this embodiment; Figure 8 This is a flowchart of the construction quality evaluation method for foamed fluidized solidified soil in this embodiment. Detailed Implementation

[0064] The technical solution of the present invention will be further described below through specific embodiments. The following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the engineering waste mud, engineering waste slag, ordinary silicate cement, finely ground blast furnace slag powder, biomass incineration ash, polycarboxylate superplasticizer, hydroxypropyl methylcellulose water-retaining agent, and composite foaming agent can all be obtained through on-site collection or commercial means. All moisture contents are calculated on a wet basis. The flowability test is performed using the truncated cone flowability test method; the unconfined compressive strength is tested using cylindrical specimens cured under standard curing conditions for 28 days; the settlement deformation is obtained through leveling measurements or periodic observations at settlement monitoring points.

[0065] Example 1 This embodiment provides a multi-source solid waste foamed fluidized bed for backfilling foundation pits and trenches. Design strength requirements. =0.60MPa, design target flow rate =180mm, design wet density =1100kg / m 3 .

[0066] Step 1: Preparation of mud base material with fixed moisture content.

[0067] Take engineering waste mud M 1 = 1000 kg, and the initial moisture content was measured by sampling at multiple points. w 1=55%; Take the waste soil from the project and measure its moisture content. w 2=8%. Based on the stability and flowability requirements of the backfilling of the foundation pit, the target moisture content is determined. w t =28%. According to the formula... Calculate the amount of waste soil to be disposed of in the project: kg 1350 kg of construction waste soil was added to 1000 kg of construction waste mud and mixed for 5 minutes using a forced mixer to obtain mud base material with a fixed moisture content, with a total mass of 2350 kg. A sample was taken for verification, and the moisture content was 28.3%, with a deviation of 0.3% from the target value, meeting the ±2% control requirement.

[0068] Step 2: Preparation of multi-source solid waste-based composite curing agent.

[0069] Dry soil quality in mud base material S =2350×(1-0.28)=1692kg. The ratio of lime to soil is taken as... C / S =10%, then the quality of multi-source solid waste-based composite curing agent C =1692×10%=169.2kg.

[0070] Weigh the following by weight percentage: 50% (84.6 kg) ordinary silicate cement, 35% (59.2 kg) finely ground blast furnace slag powder, and 15% (25.4 kg) biomass incineration ash. Add the three materials sequentially to a dry powder mixer and mix for 4 minutes until the color is uniform. Sieve the discharged material to remove any lumps, thus obtaining the multi-source solid waste-based composite curing agent.

[0071] Step 3: Determine the theoretical initial water-cement ratio and mix the fluidized solidified soil.

[0072] Based on the target moisture content w t =28% and ash-soil ratio C / S =10%, calculate the theoretical initial water-cement ratio:

[0073] The test mixture was prepared according to the theoretical initial water-cement ratio, and the flowability was measured. L =158mm, below the lower limit of 160mm. Based on the S3 feedback adjustment method, the water-cement ratio is increased to 4.20, while the lime-soil ratio remains unchanged at 10%. Total water consumption. W =4.20 × 169.2 = 710.6 kg, the water content of the mud base material. W b =2350 × 0.28 = 658.0 kg, additional mixing water added W a =710.6-658.0=52.6kg.

[0074] Weigh out 2350 kg of mud-based material, 169.2 kg of multi-source solid waste-based composite solidifying agent, and 52.6 kg of water. The dosage of polycarboxylate superplasticizer is 0.8% (1.35 kg) of the multi-source solid waste-based composite solidifying agent, and the dosage of hydroxypropyl methylcellulose water-retaining agent is 0.2% (0.34 kg) of the multi-source solid waste-based composite solidifying agent. Mix the mud-based material and water for 2 minutes, add the multi-source solid waste-based composite solidifying agent and mix for 4 minutes, then add the admixture and mix for 2 minutes to obtain a fluidized solidified soil mixture. Retest the flowability. L =184mm, T 200 =11s, no obvious bleeding or segregation, meeting construction requirements. The strength coefficient of this system was obtained by calibration using the S4 strength prediction model in the mix design method, under the condition of a soil-cement ratio C / S=10%. A =267.2、 B =4.05.

[0075] Step 4: Preparation of foamed fluidized solidified soil.

[0076] The foaming component and the foam-stabilizing component were mixed at a mass ratio of 1:4, diluted with 80 times the amount of water, and pre-formed bubbles were prepared using a physical foaming machine. The foam density was measured to be 45 kg / m³. 3 The 1-hour settlement distance was 3 mm, and the 1-hour water seepage rate was 6%, all three indicators were qualified. Pre-fabricated air bubbles were added to the mixture at a ratio of 2% of air bubble volume to dry soil mass, and stirred slowly for 90 seconds until homogeneous. The measured wet density was... =1085kg / m 3 , and design value =1100kg / m 3 Deviation of 1.36% < 5%, qualified. Foamed fluidized solidified soil is obtained.

[0077] Step 5: Collection of construction quality inspection data.

[0078] Five sets of on-site flowability data (mm) were collected at the mixing outlet, pump pipe outlet, and pouring surface: 182, 185, 183, 186, and 184.

[0079] Three sets of cylindrical specimens were prepared by sampling at the pouring site. After standard curing for 28 days, the unconfined compressive strength (MPa) was measured to be 0.78, 0.82, and 0.80.

[0080] Four settlement monitoring points were set up after construction, with a spacing of 5m between adjacent monitoring points. The cumulative settlement (mm) over 28 days was 3.2, 4.5, 4.0, and 4.8.

[0081] Step Six: Construction Quality Evaluation.

[0082] Pick =184mm, =25mm. Calculated... =0.182.

[0083] Pick =0.80MPa, =1.65. Calculated... =0.172.

[0084] Pick =12mm, =0.003. Maximum settlement 4.8mm, maximum settlement gradient 0.30mm / m. Calculated... =0.409.

[0085] Pick η =0.30, ε =0.001, substitute:

[0086]

[0087] R =0.296 < 0.40, Q =77.2>71.4, which is Grade I excellent. The construction section has passed the acceptance inspection and can proceed to the next process. Monitoring will continue at the regular frequency.

[0088] Example 2 This embodiment provides a multi-source solid waste foamed fluidized bed solidified soil for lightweight backfilling of roadbed abutments. Design required strength. =1.0MPa, design target flow rate =180mm, design wet density =1000kg / m³.

[0089] Step 1: Preparation of mud base material with fixed moisture content.

[0090] Take engineering waste mud M 1 = 800 kg, initial moisture content w 1=65%; Waste soil from the project was used, with a moisture content of... w 2 = 6%. Target moisture content w t =30%. Amount of construction waste soil disposed of: kg 1166.7 kg of slag was added to 800 kg of mud and stirred for 5 minutes to obtain 1966.7 kg of mud base material. The moisture content was checked and found to be 30.4%, which is 0.4% different from the target value, meeting the ±2% control requirement.

[0091] Step 2: Preparation of multi-source solid waste-based composite curing agent.

[0092] Dry soil quality S =1966.7×(1-0.30)=1376.7kg. The ratio of lime to soil is taken as... C / S =12%, quality of multi-source solid waste-based composite curing agent C =1376.7×12%=165.2kg.

[0093] Weigh the following by weight percentage: 48% (79.3 kg) ordinary silicate cement, 36% (59.5 kg) finely ground blast furnace slag powder, and 16% (26.4 kg) biomass incineration ash. Add the three materials sequentially to a dry powder mixer and mix for 4 minutes until the color is uniform. Sieve to remove any lumps to obtain the multi-source solid waste-based composite curing agent.

[0094] Step 3: Determine the theoretical initial water-cement ratio and mix the fluidized solidified soil.

[0095] Based on the target moisture content w t =30% and ash-soil ratio C / S =12%, calculate the theoretical initial water-cement ratio:

[0096] The fluidity of the mixture was measured by trial mixing. L =153mm, lower than 160mm. Increase the water-cement ratio to 3.90, while maintaining the lime-soil ratio at 12%. Total water consumption. W =3.90 × 165.2 = 644.3 kg, including water. W b =1966.7 × 0.30 = 590.0 kg, additional water added W a =644.3-590.0=54.3kg.

[0097] Weigh out 1966.7 kg of mud base material, 165.2 kg of multi-source solid waste-based composite curing agent, and add 54.3 kg of water. The dosage of polycarboxylate superplasticizer is 0.8% (1.32 kg) of the multi-source solid waste-based composite curing agent, and the dosage of hydroxypropyl methylcellulose water-retaining agent is 0.2% (0.33 kg) of the multi-source solid waste-based composite curing agent. Retest the flowability after mixing. L =176mm, T 200 =13s, meeting construction requirements. The strength coefficient of this system was obtained through calibration using the S4 strength prediction model in the mix design method, under the condition of a soil-cement ratio C / S=12%. A =312.6、 B =4.18.

[0098] Step 4: Preparation of foamed fluidized solidified soil.

[0099] The foam quality test was the same as in Example 1. The foam content was 2.5%, and the mixture was slowly stirred for 120 seconds until homogeneous. The actual wet density was measured. =982kg / m 3 The deviation from the design value was 1.80% < 5%, which is acceptable. Foamed fluidized solidified soil was obtained.

[0100] Step 5: Collection of construction quality inspection data.

[0101] Five sets of on-site flowability data (mm) were collected: 175, 180, 172, 178, and 176.

[0102] Three sets of unconfined compressive strength data (MPa) were measured: 1.05, 1.12, and 1.08.

[0103] Four settlement monitoring points were set up with a spacing of 4m. The cumulative settlement (mm) over 28 days was 4.2, 7.8, 6.5, and 7.0.

[0104] Step Six: Construction Quality Evaluation.

[0105] Pick =176mm, =25mm. Calculated... =0.230.

[0106] Pick =1.08MPa, =1.65. Calculated... =0.221.

[0107] Pick =15mm, =0.004. Maximum settlement 7.8mm, maximum settlement gradient 0.90mm / m. Calculated... =0.566.

[0108] Pick η =0.40, ε =0.001, substitute:

[0109]

[0110] R=0.421<0.70, Q=70.4>58.8, which is Class II qualified. The construction section can be accepted. Areas with large deviations in fluidity, strength or settlement should be re-verified. In subsequent construction, the water consumption, mixing time or pumping parameters should be optimized.

[0111] Table 2 Performance Comparison of Examples

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method for preparing multi-source solid waste-based foamed fluidized bed solidified soil, characterized in that, The multi-source solid waste-based foamed fluidized bed solidified soil, by mass percentage, consists of the following components: 78%–93% slurry base material with fixed moisture content, 4%–12% multi-source solid waste-based composite solidifying agent, 1%–10% water, water-reducing agent accounting for 0.5%–1.0% of the total mass of the multi-source solid waste-based composite solidifying agent, and water-retaining agent accounting for 0.1%–0.3% of the total mass of the multi-source solid waste-based composite solidifying agent; the bubble content is 1%–5% based on the percentage of bubble volume to the dry soil mass in the slurry base material; the multi-source solid waste-based composite solidifying agent, by mass percentage, consists of 40%–55% cement, 30%–45% finely ground blast furnace slag powder, and 10%–18% biomass incineration ash; the preparation method of the multi-source solid waste-based foamed fluidized bed solidified soil includes the following steps: Step 1: Prepare mud base material with a fixed moisture content; Step 2: Weigh out cement, finely ground blast furnace slag powder and biomass incineration ash according to the stated mass percentage, dry mix them evenly, and then prepare a multi-source solid waste-based composite curing agent. Step 3: Determine the water-cement ratio and the lime-soil ratio, calculate the total water requirement, deduct the water contained in the mud base material, determine the amount of additional water to be added, weigh the mud base material, multi-source solid waste composite solidifying agent, water, water-reducing agent, and water-retaining agent, and stir to prepare a fluidized solidified soil mixture; Step 4: Add the pre-made air bubbles to the resulting mixture and stir until the air bubbles are evenly distributed. Detect the wet density. The deviation between the measured wet density and the design value should not exceed 5%. If it is not qualified, adjust the amount of air bubbles, or adjust the reference water-cement ratio and / or lime-soil ratio until the design requirements are met, and obtain foamed fluidized solidified soil.

2. The method for preparing multi-source solid waste-based foamed fluidized bed solidified soil according to claim 1, characterized in that, In step one, the mud base material with a fixed moisture content is obtained by applying it to a mass of... M 1. Initial moisture content is w The mass of 1 part of the engineering waste mud was added X Moisture content is w The waste soil from project 2 was mixed and prepared. After preparation, samples were taken to check the moisture content, and the deviation was controlled within the target moisture content. w t Within ±2% of the mass of the waste soil mixed in the project. X The formula for determining it is: .

3. The method for preparing multi-source solid waste-based foamed fluidized bed solidified soil according to claim 1 or 2, characterized in that, Step three, determining the water-cement ratio and the lime-soil ratio, includes the following steps: S1, the theoretical initial water-cement ratio is determined based on the target moisture content. In the formula, W This represents the total water consumption. C For the quality of multi-source solid waste-based composite curing agents, S The dry soil mass in the mud slurry base material. w t For the target moisture content, w t Based on the moisture content of the wet basis C / S The ratio of ash to soil is 1:

1. W / C Water-cement ratio, W t Total water consumption required to achieve the target moisture content; S2, the theoretical initial water-cement ratio determined according to S1. W / C Compared to ash soil C / S Weigh out the mud base material, multi-source solid waste-based composite solidifying agent, water, water-reducing agent, and water-retaining agent, and mix them thoroughly to prepare a fluidized solidified soil test mixture. S3, Perform a flowability test on the prepared mixture to determine its flowability. L And record the time T required to extend to 200mm. 200 The applicable construction range is defined as a flowability of 160–200 mm. When fluidity L For diameters less than 160mm, prioritize increasing the water-cement ratio. W / C If simply increasing the water-cement ratio leads to insufficient strength reserve, then the lime-soil ratio should be appropriately reduced. C / S Alternatively, optimize the dosage of water-reducing agents and water-retaining agents; When fluidity L If the thickness is greater than 200 mm, or if the mixture shows obvious bleeding or segregation, the water-cement ratio should be reduced first. W / C If segregation is still difficult to suppress after reducing the water-cement ratio, then the lime-soil ratio should be appropriately increased. C / S ; Each time the water-cement ratio is adjusted, W / C The adjustment range is controlled between 0.1 and 0.3, and the lime-soil ratio is... C / S The adjustment range is controlled within 1% to 3%; after each adjustment, the mixture is prepared again and the flowability test is repeated until the flowability meets 160 to 200 mm and there is no obvious bleeding or segregation. S4. Once the fluidity of the mixture meets the requirements, prepare several specimens using this mix proportion and cure them to the designed age. Conduct unconfined compressive strength tests and take the average value of the strength test results of several specimens as the measured strength of this mix proportion. ; Under the condition of fixed soil-cement ratio, a strength prediction model is introduced: ， In the formula, For unconfined compressive strength, A The strength coefficient is related to the type of curing agent, soil properties, and curing conditions. B The water-cement ratio is the indices that affect the water-cement ratio. n The index affecting the soil-cement ratio; S5, measured strength Strength required by design If a comparison is made, ≥ If the flowability of the mixture still meets the requirement of 160-200 mm, then this mix proportion can be used as a candidate final mix proportion; if < The target water-cement ratio that meets the design strength requirements is obtained by inversion from the strength prediction model. The inversion formula is as follows: ， In the formula, Strength required by design specifications; After reducing the water-cement ratio based on the inversion results, the fluidity test and unconfined compressive strength test should be carried out again to determine whether it simultaneously meets the construction fluidity and design strength requirements. S6. When the design strength requirements can be met by reducing the water-cement ratio, and the fluidity is within the range of 160-200 mm, the modified water-cement ratio should be used as the final design value. When the strength increases after reducing the water-cement ratio, but the fluidity is below 160 mm, the cement-soil ratio should be increased in increments of 2%. C / S And S1 to S5 are repeated at each level of lime-soil ratio until the fluidity and strength of the mixture meet the design requirements. The mix proportion that meets the following condition is selected as the final mix proportion: 160mm ≤ L ≤200mm ≥ Furthermore, the mixture showed no obvious bleeding or segregation; the corresponding water-cement ratio W / C , Lime-soil ratio C / S The added water volume and the dosage of the multi-source solid waste-based composite solidifying agent are the final mix proportion parameters of the multi-source solid waste foamed fluidized solidified soil, and the corresponding fluidity value of the mixture is recorded as the design reference fluidity. .

4. The method for preparing multi-source solid waste-based foamed fluidized bed solidified soil according to claim 3, characterized in that, In step four, the amount of bubble content is adjusted in increments of 0.2% to 0.5%.

5. The method for preparing multi-source solid waste-based foamed fluidized bed solidified soil according to claim 3, characterized in that, In step four, the bubbles are prepared using a pre-foaming method. The foaming agent used is a composite foaming agent composed of a foaming component and a foam-stabilizing component. The foaming component is mainly composed of anionic surfactants, and the foam-stabilizing component is mainly composed of alkylolamides and silicone polyethers. In use, the foaming component and the foam-stabilizing component are first mixed at a mass ratio of 1:4, then diluted with 80 times their mass of water to form a foaming liquid. Compressed air is then introduced through a physical foaming machine to create pre-formed bubbles. The foam density of the pre-formed bubbles... 40-50 kg / m 3 The settling distance in 1 hour should not exceed 5 mm, and the water bleeding rate in 1 hour should not exceed 10%.

6. The method for preparing multi-source solid waste-based foamed fluidized bed solidified soil according to claim 3, characterized in that, The water-reducing agent is a polycarboxylate-based water-reducing agent, and the water-retaining agent is hydroxypropyl methylcellulose.

7. The method for preparing multi-source solid waste-based foamed fluidized bed solidified soil according to claim 2, characterized in that, The initial moisture content of the waste mud from the project w 1. Take the average value of multiple samples taken on site, and the target moisture content. w t The optimal moisture content value is obtained by referring to the soil liquid limit or compaction test.

8. The method for preparing multi-source solid waste-based foamed fluidized bed solidified soil according to claim 3, characterized in that, The cement is ordinary Portland cement of grade PO 42.5 or above.

9. The method for preparing multi-source solid waste-based foamed fluidized bed solidified soil according to claim 3, characterized in that, The finely ground blast furnace slag powder is made from molten slag discharged during the blast furnace ironmaking process in the iron and steel industry. It is produced by water quenching, drying, and grinding, with a particle size of no more than 30 μm and a specific surface area of ​​no less than 400 m². 2 / kg; The biomass incineration ash is made from beer lees or vinegar lees produced in the brewing industry. After drying and crushing, it is incinerated at 600℃~800℃ under aerobic conditions for 2h~4h, and then ground until the residue on a 45μm square hole sieve is no more than 30%.

10. A quality control method for multi-source solid waste-based foamed fluidized bed solidified soil obtained by the preparation method according to claim 3, comprising the following steps: Step 1: During construction, samples are taken at one or more locations, including the mixing outlet, pump outlet, and pouring surface, to collect on-site flowability data of the foamed fluidized solidified soil. ; Samples were taken at the pouring site to prepare specimens for unconfined compressive strength tests, and strength test data were obtained. After construction is completed, settlement monitoring points are set up at equal intervals on the surface of the backfill to collect settlement and deformation data. and the distance between adjacent monitoring points ; Step 2: Calculate the flowability compatibility index based on the on-site flowability test data. The calculation formula is: ， In the formula, For the first i The on-site flowability test value. To design the baseline flowability, To allow for flowability deviation, n The number of flowability tests; Step 3: Calculate the strength reliability index based on the unconfined compressive strength test data. The calculation formula is as follows: ， In the formula, For the first j Unconfined compressive strength of the group of specimens; To predict the theoretical strength, the strength value calculated based on the final mix proportion in the strength prediction model is used. , W / C The final water-cement ratio; m The number of strength test specimen groups; The intensity characteristic value is calculated using the following formula: ; To ensure strength, the correction factor is set between 1.28 and 1.

65. Step 4: Calculate the settlement deformation stability index based on the settlement deformation monitoring data. The calculation formula is as follows: ， In the formula, The absolute value (mm) of the maximum cumulative settlement among all monitoring points; The maximum allowable settlement value (mm) is taken as 5-15mm; The maximum settlement gradient between adjacent monitoring points; For the first i The and the first j The distance between monitoring points; The settlement gradient limit is generally set between 0.002 and 0.

005. Step 5: Based on the fluid filling compatibility index, strength reliability index, and settlement deformation stability index, establish a comprehensive construction quality risk index. R The calculation formula is as follows: ， In the formula, The coefficient for coupling amplification of the index is taken as 0.20 to 0.50, and 0.40 to 0.50 for important projects; To prevent extremely small positive numbers with a denominator of zero, we take 0.001; Step Six: Based on the comprehensive construction quality risk index R Calculate the overall construction quality score Q The construction quality of fluidized solidified soil is graded and judged, and the acceptance, verification, re-grouting, reinforcement or rework measures are determined based on the judgment results. Q The calculation formula is: ， The quality grade is determined as follows: Q≥71.4, Excellent; 58.8≤Q<71.4, qualified; 50.0≤Q<58.8, basically qualified; 43.5≤Q<50.0, high quality risk; Q<43.5, unqualified.

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