Method for synergistic solidification of high water content high humus muck

Abstract

This invention discloses a method for the synergistic solidification of high-moisture, high-humus swamp soil, belonging to the field of road engineering materials technology. The method involves first adding sodium polyacrylate water-absorbing resin modified by gamma-ray irradiation to selectively remove free water from the soil; then adding a ferrous sulfate-reed-based biochar composite modifier to allow the ferrous sulfate to combine with the active groups of humic substances to form a stable complex, reducing humic activity and enabling resource utilization; finally, adding an active MgO-sodium hexametaphosphate composite binder to remove residual water through a hydration reaction and form a cemented structure. This method improves upon traditional solidification processes by addressing issues such as insufficient coordination between dehydration and cementation, and significant interference from humic substances in the cementation process. The resulting solidified soil exhibits an unconfined compressive strength of at least 1 MPa after 1 day of curing and a strength retention rate of at least 75% after 24 hours of immersion in water. During solidification, ferrous sulfate inhibits the activity of methanogenic bacteria, reducing methane emissions by more than 60% compared to untreated soil. It demonstrates good engineering performance and environmental friendliness, and can be used for foundation treatment and filling projects of swamp soil in wetlands, peatlands, and other areas.

Description

Technical Field

[0001] This invention belongs to the field of road engineering materials technology, and in particular relates to a method for synergistic solidification of high-moisture-content, high-humus swamp soil. Background Technology

[0002] Swamp soil is widely distributed in the Sanjiang Plain in Northeast my country, the Ruoergai Wetland in Southwest China, and the lake wetlands in the middle and lower reaches of the Yangtze River. Its typical engineering geological characteristics are high natural water content, large porosity, high organic matter content, low bearing capacity, and high compressibility. When used directly as engineering foundation, roadbed filling, or land reclamation material, it is prone to engineering problems such as uneven settlement, shear instability, and long-term strength degradation.

[0003] Existing swamp soil solidification technologies are mainly divided into two categories: dehydration modification and cementation solidification. Single dehydration technology often uses ordinary water-absorbing resin, vacuum preloading, or natural drying. Among these, ordinary water-absorbing resin has problems such as poor water absorption selectivity and easy desorption and water return. Vacuum preloading and drying methods have long construction cycles and are significantly affected by climate. Single cementation solidification technology often uses traditional cementing agents such as cement and lime. Because humus will coat soil particles and adsorb cementing agent hydration products, and its acidic environment will inhibit the cementing agent hydration reaction process, the solidified body has low early strength, slow later strength growth, and poor water stability.

[0004] To address the negative impact of high humic content on the solidification effect, existing technologies mainly employ physical sieving to remove humic substances or the addition of chemical inhibitors such as sodium hydroxide and calcium chloride to reduce their activity. Physical removal methods are costly, and the humic waste generated during sieving can easily cause secondary pollution; chemical inhibition methods can only partially weaken the interfering effect of humic substances and cannot fundamentally solve their destructive impact on the cementing system, while also wasting humic resources.

[0005] Therefore, developing a method for solidifying marsh soil that can simultaneously achieve efficient dehydration, humus resource utilization, and high-strength cementation has significant engineering implications and application value. Summary of the Invention

[0006] Existing technologies generally suffer from problems such as independent and insufficient synergy between dehydration and cementation processes, significant interference of humus on the hydration reaction of the cementation system, low strength and poor water stability of the solidified body, low utilization of humus resources, and inadequate control of greenhouse gas emissions during the solidification process. To overcome these shortcomings of existing swamp soil solidification technologies, this invention proposes a synergistic solidification method for high-moisture-content, high-humus-content swamp soil. This invention achieves efficient soil dehydration, humus stabilization, and cementation solidification in an integrated manner through multi-component synergistic action and stepwise treatment, thereby solving the aforementioned technical bottlenecks and improving the engineering performance and environmental friendliness of the solidified soil.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for the synergistic solidification of high-moisture-content, high-humus-content marsh soil, comprising the following steps: (1) Add γ-ray irradiated modified sodium polyacrylate water-absorbing resin to swamp soil with high water content and high humus, stir evenly and let stand to complete the first stage of dehydration. (2) The high-moisture, high-humus swamp soil after the first stage of dehydration is crushed and screened to obtain pretreated high-humus swamp soil. (3) Add ferrous sulfate-reed biochar composite modifier to the pretreated swamp soil, stir evenly and let stand. Ferrous sulfate combines with active groups such as carboxyl and hydroxyl groups in humus to form a stable iron-humus complex, thus completing the chemical passivation of humus. (4) Add active MgO-sodium hexametaphosphate composite binder to the swamp soil after chemical passivation of humus, stir evenly, and the active MgO reacts with the residual water to generate magnesium hydroxide, achieving the second stage of dehydration. At the same time, under the dispersion of sodium hexametaphosphate, it combines with soil particles to form a cement network. (5) Mix the dehydrated marsh soil from the second stage evenly, compact it to the target compaction degree, and place it in a standard environment for curing until the specified age.

[0008] This invention employs a series of steps to solidify marsh soil: selective removal of free water, humus modification, hydration dehydration, and cementation solidification. First, sodium polyacrylate superabsorbent polymer (SAP) modified by gamma-ray irradiation is added to selectively remove free water from the soil. Next, a ferrous sulfate-reed biochar composite modifier is added, allowing the ferrous sulfate to combine with the active groups of humus to form a stable complex, reducing humus activity and enabling resource utilization. Finally, an active MgO-sodium hexametaphosphate composite cementing agent is added, removing residual water through hydration and forming a cemented structure. This method improves upon traditional solidification processes by addressing issues such as insufficient coordination between dehydration and cementation, and significant interference from humus in the cementation process. This invention employs a step-by-step control mechanism: first, gamma-ray modified water-absorbing resin selectively removes free water from the soil, reducing excess moisture in advance and preventing excessive moisture from disrupting subsequent gelation hydration; then, ferrous sulfate ions complex with the active groups of humic substances to passivate organic matter, supplemented by reed biochar adsorption to fix the humic complex, blocking the side effects of humic substances encapsulating the gelling agent and inhibiting hydration from the source; finally, active MgO hydration consumes residual moisture, and a gelling skeleton is stably generated under the control of sodium hexametaphosphate, achieving a phased and orderly match between water control and cementation, thus solving the two major problems of uncoordinated dehydration and cementation and interference with solidification in traditional processes. The solidified soil prepared by this invention has an unconfined compressive strength ≥1MPa after 1 day of curing and a strength retention rate ≥75% after 24 hours of immersion in water; during the solidification process, ferrous sulfate can inhibit the activity of methanogenic bacteria, reducing methane emissions by more than 60% compared to untreated soil, exhibiting good engineering performance and environmental friendliness, and can be used for foundation treatment and filling projects of marsh soil in wetlands, peatlands, and other areas.

[0009] Further, in step (1), the natural water content (determined by drying method) of the high water content and high humus swamp soil is ≥60%, and the humus content (determined by potassium dichromate titration method) is ≥10%.

[0010] Further, in step (1), the amount of the γ-ray irradiation modified sodium polyacrylate water-absorbing resin is 0.2% to 0.5% of the dry weight of the high water content and high humus swamp soil.

[0011] Furthermore, in step (1), the γ-ray irradiation modified sodium polyacrylate water-absorbing resin has a water absorption ratio of 300 to 500 times its own mass for free water and does not adsorb humic bound water.

[0012] Further, in step (1), the method for preparing the γ-ray irradiation modified sodium polyacrylate water-absorbing resin is as follows: the sodium polyacrylate water-absorbing resin is irradiated with γ-rays, the irradiation dose is 20~40kGy, and the irradiation time is 1~2.5h.

[0013] Further, in step (3), the amount of ferrous sulfate in the ferrous sulfate-reed biochar composite modifier is 0.3% to 0.8% of the dry weight of the high water content and high humus swamp soil, and the amount of reed biochar is 1% to 3% of the dry weight of the high water content and high humus swamp soil.

[0014] Further, in step (3), the reed-based biochar is prepared by low-temperature pyrolysis of native reeds from swamps. The preparation method of the reed-based biochar is as follows: pyrolyze the reeds at 300~450℃ for 2.5~4h, crush them and pass them through a 100-mesh sieve to obtain the reed-based biochar.

[0015] Further, in step (4), in the active MgO-sodium hexametaphosphate composite binder, the amount of active MgO is 4%~8% of the dry weight of the high water content and high humus swamp soil, and the amount of sodium hexametaphosphate is 2%~5% of the mass of active MgO.

[0016] Furthermore, in step (4), the citric acid activity value of the active MgO is between 12 and 20 s.

[0017] Furthermore, in step (5), the target compaction degree is 96%.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects: This invention employs a stepwise dehydration and simultaneous cementation process. In the first stage, modified water-absorbing resin selectively adsorbs free water and initially coats soil particles. In the second stage, active MgO hydration removes residual water and forms a dense cementation network. Dehydration and cementation proceed synergistically, resulting in high early strength of the solidified body and a short construction cycle. Ferrous sulfate is used to chemically passivate humus, eliminating its interference with the cementation reaction. Combined with reed-based biochar, humus resources are utilized, transforming humus into reinforcing components for the solidified body and improving its long-term stability. Biochar is prepared using native swamp reeds, resulting in low-cost, locally sourced materials. The biochar can adsorb harmful substances in the soil, while ferrous sulfate can inhibit methanogenic bacteria activity and reduce greenhouse gas emissions, combining soil solidification and ecological restoration functions, thus meeting the requirements of green engineering. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a process flow diagram of the synergistic solidification method for high-moisture-content, high-humus marsh soil according to the present invention. Detailed Implementation

[0020] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0021] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0022] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0023] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0024] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0025] An embodiment of the present invention provides a method for the synergistic solidification of high-moisture-content, high-humus-content marsh soil, comprising the following steps: (1) Add γ-ray irradiated modified sodium polyacrylate water-absorbing resin to swamp soil with high water content and high humus, stir evenly and let stand to complete the first stage of dehydration. (2) The high-moisture, high-humus swamp soil after the first stage of dehydration is crushed and screened to obtain pretreated high-humus swamp soil. (3) Add ferrous sulfate-reed biochar composite modifier to the pretreated swamp soil, stir evenly and let stand. Ferrous sulfate combines with active groups such as carboxyl and hydroxyl groups in humus to form a stable iron-humus complex, thus completing the chemical passivation of humus. (4) Add active MgO-sodium hexametaphosphate composite binder to the swamp soil after chemical passivation of humus, stir evenly, and the active MgO reacts with the residual water to generate magnesium hydroxide, achieving the second stage of dehydration. At the same time, under the dispersion of sodium hexametaphosphate, it combines with soil particles to form a cement network. (5) Mix the dehydrated marsh soil from the second stage evenly, compact it to the target compaction degree, and place it in a standard environment for curing until the specified age.

[0026] The cured body obtained by the method of the present invention has an unconfined compressive strength of ≥1.0MPa after 1 day of curing and a strength retention rate of ≥75% after 24 hours of immersion in water.

[0027] In a preferred embodiment of the present invention, in step (1), the natural water content (determined by the drying method) of the high water content and high humus swamp soil is ≥60%, and the humus content (determined by the potassium dichromate titration method) is ≥10%.

[0028] In a preferred embodiment of the present invention, in step (1), the amount of γ-ray irradiation modified sodium polyacrylate water-absorbing resin is 0.2% to 0.5% of the dry weight of high water content and high humus swamp soil.

[0029] In a preferred embodiment of the present invention, in step (1), the γ-ray irradiation modified sodium polyacrylate water-absorbing resin absorbs free water at a rate of 300 to 500 times its own mass, and does not adsorb humic bound water.

[0030] In a preferred embodiment of the present invention, in step (1), the method for preparing the γ-ray irradiation modified sodium polyacrylate water-absorbing resin is as follows: the sodium polyacrylate water-absorbing resin is irradiated with γ-rays, the irradiation dose is 20~40kGy, and the irradiation time is 1~2.5h.

[0031] For example, in step (1), the stirring time is 2-3 minutes and the standing time is 10-30 minutes.

[0032] In a preferred embodiment of the present invention, in step (3), the amount of ferrous sulfate in the ferrous sulfate-reed biochar composite modifier is 0.3% to 0.8% of the dry weight of the high-moisture-content, high-humus swamp soil, and the amount of reed biochar is 1% to 3% of the dry weight of the high-moisture-content, high-humus swamp soil.

[0033] In a preferred embodiment of the present invention, in step (3), the reed-based biochar is prepared by low-temperature pyrolysis of native reeds from swamps. The preparation method of the reed-based biochar is as follows: the reeds are pyrolyzed at 300~450℃ for 2.5~4h, crushed and passed through a 100-mesh sieve to obtain the reed-based biochar.

[0034] For example, in step (3), the stirring time is 3-4 min and the standing time is 20-40 min.

[0035] In a preferred embodiment of the present invention, in step (4), the amount of active MgO in the active MgO-sodium hexametaphosphate composite binder is 4% to 8% of the dry weight of the high-moisture, high-humus marsh soil, and the amount of sodium hexametaphosphate is 2% to 5% of the mass of active MgO.

[0036] In a preferred embodiment of the present invention, in step (4), the citric acid activity value of the active MgO is between 12 and 20 s.

[0037] For example, the stirring time in step (4) is 3 to 5 minutes.

[0038] In a preferred embodiment of the present invention, in step (5), the target compaction degree is 96%.

[0039] The standard maintenance environment in step (5) is a temperature of 20±2℃ and a relative humidity of 95% or higher.

[0040] This invention employs a series of steps to solidify marsh soil: selective removal of free water, humus modification, hydration dehydration, and cementation solidification. First, sodium polyacrylate water-absorbing resin modified by gamma-ray irradiation is added to selectively remove free water from the soil. Then, a ferrous sulfate-reed biochar composite modifier is added, allowing the ferrous sulfate to combine with the active groups of humus to form a stable complex, reducing humus activity and enabling resource utilization. Finally, an active MgO-sodium hexametaphosphate composite cementing agent is added, removing residual water through hydration and forming a cemented structure. The method of this invention can improve the problems of insufficient coordination between dehydration and cementation and significant interference of humus on the cementation process in traditional solidification processes. The solidified soil obtained has an unconfined compressive strength of not less than 1 MPa after 1 day of curing and a strength retention rate of not less than 75% after 24 hours of immersion in water. During the solidification process, ferrous sulfate can inhibit the activity of methanogenic bacteria, and the methane emission is reduced by more than 60% compared with the untreated soil. It has good engineering performance and environmental friendliness and can be used for foundation treatment and filling projects of swamp soil in wetlands, peatlands and other areas.

[0041] Unless otherwise specified, the room temperature in this invention is 25±2℃.

[0042] All raw materials used in the embodiments of this invention were purchased commercially. For example, sodium polyacrylate superabsorbent polymer was purchased from Renqiu Shuangcheng Chemical Products Factory, model number 9003-04-6, with a mesh size of 80-200 mesh.

[0043] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0044] The technical solution of the present invention will be further illustrated by the following embodiments.

[0045] Example 1 A method for synergistic solidification of high-moisture-content, high-humus-content marsh soil, comprising the following steps: (1) Selective removal of free water in the first stage: Swamp soil from a wetland in the Sanjiang Plain of Northeast China was collected (the natural water content was determined to be 85% by drying method and the humic content was determined to be 12% by potassium dichromate volumetric method). 0.3% of the dry soil mass of γ-ray irradiated modified sodium polyacrylate water-absorbing resin was added to the swamp soil. The irradiation dose was 30 kGy and the irradiation time was 2 h. The water absorption ratio of the γ-ray irradiated modified sodium polyacrylate water-absorbing resin to free water was 400 times its own mass, and it did not adsorb the water bound to humic substances. The mixture was stirred for 2 min with a forced mixer (speed of 80±4 r / min) until uniform and then allowed to stand for 20 min.

[0046] (2) Screening and crushing treatment: For the marsh soil after the first stage of dehydration, stones, plant roots and other impurities with a particle size greater than 50mm are manually removed; after the dried soil sample is crushed, it is screened through a 10mm sieve; the agglomerates remaining on the sieve are further crushed and ground until they all pass through the 10mm sieve.

[0047] (3) Chemical passivation modification of humus: Add 0.5% ferrous sulfate and 2% reed-based biochar (the preparation method of reed-based biochar is: pyrolyze reeds at 400℃ for 3 hours, crush them and pass them through a 100-mesh sieve to obtain reed-based biochar), stir for 3 minutes until uniform, and let stand for 30 minutes.

[0048] (4) Second stage hydration, dehydration and synchronous cementation and solidification: Add 6% of the dry soil mass of active MgO (citric acid activity value of 12s) and 3% of the active MgO mass of sodium hexametaphosphate, and stir for 4 minutes until uniform.

[0049] (5) Molding and curing: The mixture is statically compacted to 96% compaction degree and placed in a standard environment with a temperature of 20±2℃ and a relative humidity of 95% or more for curing and molding.

[0050] Test results: According to the "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" (JTG 3441—2024), the unconfined compressive strength after 1 day of curing was 1.2 MPa, after 7 days of curing was 2.5 MPa, and after 28 days of curing was 3.8 MPa; the strength retention rate after 24 hours of immersion in water was 82%; and the methane emission was reduced by 65% ​​compared with the unmodified blank group.

[0051] Example 2 A method for synergistic solidification of high-moisture-content, high-humus-content marsh soil, comprising the following steps: (1) Selective removal of free water in the first stage: Soil from a peat bog in Ruoergai, Southwest China (with a natural water content of 92% and a humus content of 15%) was collected. 0.4% of the dry soil mass of γ-ray irradiated modified sodium polyacrylate water-absorbing resin was added. The irradiation dose was 40 kGy and the irradiation time was 2.5 h. The γ-ray irradiated modified sodium polyacrylate water-absorbing resin had a water absorption ratio of 450 times its own mass for free water and did not adsorb water bound to humus. The mixture was stirred for 3 min and allowed to stand for 25 min.

[0052] (2) Screening and crushing treatment: For the marsh soil after the first stage of dehydration, stones, plant roots and other impurities with a particle size greater than 50mm are manually removed; after the dried soil sample is crushed, it is screened through a 10mm sieve; the agglomerates remaining on the sieve are further crushed and ground until they all pass through the 10mm sieve.

[0053] (3) Chemical passivation modification of humus: Add 0.8% ferrous sulfate and 3% reed-based biochar (pyrolyze the reed at 450℃ for 2.5h, crush it and pass it through a 100-mesh sieve to obtain reed-based biochar), stir for 4min, and let stand for 35min.

[0054] (4) Second stage hydration, dehydration and synchronous bonding and solidification: Add 8% of the dry soil mass of active MgO (citric acid activity value of 18s) and 5% of the active MgO mass of sodium hexametaphosphate, and stir for 5 minutes until uniform.

[0055] (5) Molding and curing: Compact with static pressure to 96% compaction degree, and cure in a standard environment.

[0056] Test results: According to the "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" (JTG 3441—2024), the unconfined compressive strength after 1 day of curing was 1.1 MPa, after 7 days of curing was 2.3 MPa, and after 28 days of curing was 3.5 MPa; the strength retention rate after 24 hours of immersion in water was 79%; and the methane emission was reduced by 71% compared with the control group.

[0057] Example 3 A method for synergistic solidification of high-moisture-content, high-humus-content marsh soil, comprising the following steps: (1) Selective removal of free water in the first stage: Soil from a wetland in the middle and lower reaches of the Yangtze River was collected (the natural water content was measured to be 78% and the humus content was 10%). 0.2% of the dry soil mass of γ-ray irradiated modified sodium polyacrylate water-absorbing resin was added. The irradiation dose was 20 kGy and the irradiation time was 1 h. The γ-ray irradiated modified sodium polyacrylate water-absorbing resin had a water absorption ratio of 300 times its own mass for free water and did not adsorb water bound to humus. Stir for 2 min and let stand for 10 min.

[0058] (2) Screening and crushing treatment: For the marsh soil after the first stage of dehydration, stones, plant roots and other impurities with a particle size greater than 50mm are manually removed; after the dried soil sample is crushed, it is screened through a 10mm sieve; the agglomerates remaining on the sieve are further crushed and ground until they all pass through the 10mm sieve.

[0059] (3) Chemical passivation modification of humus: Add 0.3% ferrous sulfate and 1% reed-based biochar (pyrolyze the reed at 300℃ for 4 hours, crush it and pass it through a 100-mesh sieve to obtain reed-based biochar), stir for 3 minutes and let stand for 20 minutes.

[0060] (4) Second stage hydration, dehydration and synchronous bonding and solidification: Add 4% of the dry soil mass of active MgO (citric acid activity value of 15s) and 2% of the active MgO mass of sodium hexametaphosphate, and stir for 3 minutes until uniform.

[0061] (5) Molding and curing: Compact with static pressure to 96% compaction degree, and cure in a standard environment.

[0062] Test results: According to the "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" (JTG 3441—2024), the unconfined compressive strength after 1 day of curing was 1.0 MPa, after 7 days of curing was 2.1 MPa, and after 28 days of curing was 3.2 MPa; the strength retention rate after 24 hours of immersion in water was 76%; and the methane emission was reduced by 62% compared with the control group.

[0063] Comparative Example 1 (Traditional Cement Curing Method) Using the same swamp soil as in Example 1, add 10% of P・O42.5 ordinary Portland cement by dry weight of the soil, mix evenly, and then statically compact to 96% compaction degree, followed by standard environmental curing.

[0064] Test results: According to the "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" (JTG 3441—2024), the unconfined compressive strength after 1 day of curing is 0.3 MPa, the unconfined compressive strength after 7 days of curing is 1.1 MPa, and the unconfined compressive strength after 28 days of curing is 1.8 MPa; the strength retention rate after 24 hours of immersion in water is 55%.

[0065] Comparative Example 2 (Unmodified water-absorbing resin + cement curing method) Using the same swamp soil as in Example 1, 0.3% of unmodified sodium polyacrylate superabsorbent polymer (free water absorption ratio of 150 times) and 10% of P・O42.5 ordinary silicate cement were added. After mixing evenly, the mixture was compacted to 96% compaction degree and cured in a standard environment.

[0066] Test results: According to the "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" (JTG 3441—2024), the unconfined compressive strength after 1 day of curing is 0.5 MPa, the unconfined compressive strength after 7 days of curing is 1.4 MPa, and the unconfined compressive strength after 28 days of curing is 2.2 MPa; the strength retention rate after 24 hours of immersion in water is 62%.

[0067] Comparative Example 3 (Humus Inhibition + Cement Solidification Method) Using the same swamp soil as in Example 1, 0.5% sodium hydroxide and 10% P·O42.5 ordinary silicate cement by dry weight were added, mixed evenly, and compacted to 96% compaction degree. The mixture was then cured in a standard environment.

[0068] Test results: According to the "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" (JTG 3441—2024), the unconfined compressive strength after 1 day of curing is 0.7 MPa, the unconfined compressive strength after 7 days of curing is 1.6 MPa, and the unconfined compressive strength after 28 days of curing is 2.5 MPa; the strength retention rate after 24 hours of immersion in water is 68%.

[0069] The test results from the above examples and comparative examples show that the early strength, long-term strength, and water stability of the solidified soil obtained by the synergistic solidification method of this invention are significantly better than those of traditional cement solidification, unmodified resin solidification, and humic substance inhibition solidification methods. In Examples 1-3, the unconfined compressive strength after 1 day of curing is ≥1.0 MPa, the strength after 28 days is ≥3.2 MPa, and the strength retention rate after 24 hours of immersion in water is ≥76%. In contrast, the strength after 1 day of curing in Comparative Examples 1-3 is only 0.3-0.7 MPa, the strength after 28 days is only 1.8-2.5 MPa, and the highest strength retention rate after immersion in water is only 68%. Furthermore, this invention, through the inhibitory effect of ferrous sulfate on methanogens, can reduce methane emissions by more than 60%, combining improved engineering performance with environmental friendliness.

[0070] The above results show that the present invention effectively solves the technical problems of low solidification strength, poor stability, and significant humus interference in marsh soil under high water content and high humus conditions through the synergistic effect of stepwise dehydration, humus passivation, and synchronous cementation.

[0071] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for synergistic stabilization of high water content, high humus muck, characterized by, Includes the following steps: (1) Add γ-ray irradiated modified sodium polyacrylate water-absorbing resin to swamp soil with high water content and high humus, stir evenly and let stand to complete the first stage of dehydration. (2) The high-moisture, high-humus swamp soil after the first stage of dehydration is crushed and screened to obtain pretreated high-humus swamp soil. (3) Add ferrous sulfate-reed biochar composite modifier to the pretreated swamp soil, stir evenly and let stand to complete the chemical passivation of humus. (4) Add active MgO-sodium hexametaphosphate composite binder to the swamp soil after chemical passivation of humus, stir evenly, and complete the second stage of dehydration; (5) Mix the dehydrated marsh soil from the second stage evenly, compact it to the target compaction degree, and place it in a standard environment for curing until the specified age.

2. The high-moisture high-humic-organic-matter-bog-soil synergistic solidification method according to claim 1, characterized in that, In step (1), the natural water content of the high water content and high humus swamp soil is ≥60%, and the humus content is ≥10%.

3. The high moisture high muck peat soil synergistic solidification method of claim 1 wherein, In step (1), the amount of the γ-ray irradiation modified sodium polyacrylate water-absorbing resin used is 0.2% to 0.5% of the dry weight of the high water content and high humus swamp soil.

4. The high-moisture high-humic-organic- matter-bog-soil-collaborative- solidification method according to claim 3, characterized in that, In step (1), the γ-ray irradiation modified sodium polyacrylate water-absorbing resin has a water absorption ratio of 300 to 500 times its own mass for free water and does not adsorb humic bound water.

5. The high-moisture high-humic-organic- matter-bog-soil-collaborative- solidification method according to claim 4, characterized in that, In step (1), the preparation method of the γ-ray irradiation modified sodium polyacrylate water-absorbing resin is as follows: the sodium polyacrylate water-absorbing resin is irradiated with γ-rays, the irradiation dose is 20~40kGy, and the irradiation time is 1~2.5h.

6. The high-moisture high-humic-organic- matter-bog-soil-collaborative- solidification method according to claim 1, characterized in that, In step (3), the amount of ferrous sulfate in the ferrous sulfate-reed biochar composite modifier is 0.3% to 0.8% of the dry weight of the high water content and high humus swamp soil, and the amount of reed biochar is 1% to 3% of the dry weight of the high water content and high humus swamp soil.

7. The method for synergistic solidification of high-moisture-content, high-humus-content marsh soil according to claim 6, characterized in that, In step (3), the preparation method of the reed-based biochar is as follows: the reed is pyrolyzed at 300~450℃ for 2.5~4h, crushed and passed through a 100-mesh sieve to obtain the reed-based biochar.

8. The method for synergistic solidification of high-moisture-content, high-humus-content marsh soil according to claim 1, characterized in that, In step (4), the amount of active MgO in the active MgO-sodium hexametaphosphate composite binder is 4% to 8% of the dry weight of the high water content and high humus swamp soil, and the amount of sodium hexametaphosphate is 2% to 5% of the mass of active MgO.

9. The method for synergistic solidification of high-moisture-content, high-humus-content marsh soil according to claim 8, characterized in that, In step (4), the citric acid activity value of the active MgO is between 12 and 20 s.

10. The method for synergistic solidification of high-moisture-content, high-humus-content marsh soil according to claim 1, characterized in that, In step (5), the target compaction degree is 96%.

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