Material and method for repairing and reinforcing rock-soil ruins by in-situ excitation of indigenous microorganism mineralization

Abstract

The invention discloses a material and method for repairing and reinforcing rock-soil ruins by in-situ excitation of indigenous microorganism mineralization, and belongs to the technical field of building material and cultural heritage protection. The method comprises the following steps: detecting and analyzing a soil sample to determine inherent key mineralized microbial flora types and soil properties of the soil sample; a specific activation solution is prepared according to the formula and applied in a grouting, spraying or building and repairing mode according to different diseases, and meanwhile, a suitable environment is built to activate and enrich the indigenous key flora; then, cementing liquid is injected into the soil in a permeating mode, activated flora is induced to be subjected to mineralization reaction to generate calcium carbonate sediment, and reinforcement and remediation are achieved; temperature and humidity maintenance needs to be carried out in the process and later period. The used materials are the activating liquid and the cementing liquid. The ruin local microorganisms are directly activated and utilized, the defect of introduction of exogenous bacteria is avoided, and the method has the advantages of uniform restoration, ecological compatibility, environment friendliness and high applicability and conforms to the minimum intervention principle of cultural relic protection.

Description

Technical Field

[0001] This invention belongs to the field of building materials and cultural heritage protection technology, specifically relating to a material and method for in-situ stimulating indigenous microbial mineralization to repair and reinforce rock and soil sites. Background Technology

[0002] Earthen site ruins are important cultural heritage sites in my country, primarily constructed from rammed or masonry materials such as silty clay and silty sand. While soil materials possess high strength when dry, they are prone to disintegration when wet, and under long-term natural environmental influences, they are susceptible to cracking, erosion, and other damage, seriously threatening the long-term preservation of the sites. Traditional methods for restoring and reinforcing earthen sites mainly include chemical reinforcement, physical reinforcement, and chemical anchoring. Chemical reinforcement methods (such as injecting water glass or epoxy resin) may alter the original appearance of the artifacts and have poor compatibility with the soil; physical reinforcement methods (such as supports and anchoring) often affect the appearance of the site, violating the principle of "not altering the original state of the artifacts." These methods have limited effectiveness in repairing minor cracks and may also present durability and environmental issues.

[0003] In recent years, microbial-induced calcium carbonate precipitation technology has provided a new approach for the restoration of earthen sites due to its advantages such as being green, environmentally friendly, and having good compatibility. This technology mainly utilizes the metabolic activities of certain microorganisms to alter the microenvironment, inducing calcium carbonate crystallization and deposition, thereby cementing loose particles and filling cracks. However, most existing microbial remediation technologies rely on introducing high-concentration, purely cultured exogenous microbial solutions from external sources. This method has significant limitations in practical applications: (1) Environmental adaptability issues: Exogenous strains may not be able to effectively colonize and reproduce in the complex native soil environment of the site, and compete with and exclude native microorganisms, resulting in low survival rates.

[0004] (2) Uneven distribution and low efficiency: When the exogenous bacterial solution is injected into soil with complex and uneven pore structure, it is difficult to achieve uniform distribution. This often leads to the mineralization reaction being concentrated near the injection port, resulting in poor repair effect of deep or fine cracks and uneven distribution of the generated calcium carbonate precipitate.

[0005] (3) Potential ecological risks: The introduction of non-native microorganisms may cause unknown disturbances or biological invasion risks to the original microbial ecosystem of the site, which has important historical information.

[0006] (4) Process complexity and cost: The cultivation, propagation, storage and transportation of exogenous strains increase the complexity and cost of the process.

[0007] Therefore, there is an urgent need and significant practical importance to develop a restoration and reinforcement technology that can overcome the above-mentioned defects, directly utilize the inherent microbial resources of the site soil that have adapted to the local environment, and achieve efficient, uniform, environmentally friendly restoration with minimal interference to the site itself. Summary of the Invention

[0008] (a) Technical problems to be solved To address the shortcomings of existing exogenous microbial remediation technologies, such as poor environmental adaptability, uneven remediation, potential ecological risks, and possible violations of cultural relic protection principles, this invention aims to provide a material and method for in-situ stimulating indigenous microbial mineralization for the remediation and reinforcement of rock and soil archaeological sites. The core of this method lies in "using locally sourced materials and activating their utilization." This involves identifying key indigenous mineralizing microbial communities in the site's soil, targeting and enriching them with a specialized activating solution to make them the dominant functional microbial communities, and then inducing a mineralization reaction by providing a cementing solution (calcium source) to generate calcium carbonate precipitates. This achieves in-situ, uniform, and ecological remediation and reinforcement of cracks, weathered layers, and collapsed areas of the archaeological site.

[0009] (II) Technical Solution To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a material for in-situ stimulating indigenous microbial mineralization to repair and reinforce rock and soil sites, characterized in that it comprises: Activation solution: A solution used to specifically stimulate and promote the growth and reproduction of inherent key mineralizing microbial communities in geotechnical sites. Its composition is determined according to the metabolic type of the target key mineralizing microbial community and contains specific nutrient substrates required for the growth and reproduction of this community, specifically: (1) An activation solution for urease-producing bacteria, which is an alkaline solution containing urea and microbial nutrients; (2) Activation solution for denitrifying bacteria, anaerobic culture medium containing nitrate and organic carbon source; (3) Activation solution for sulfate-reducing bacteria, an anaerobic culture medium containing sulfate and electron donors.

[0010] Cementing solution: A solution that provides calcium ions for microbial mineralization deposition, specifically: The cementing solution is a solution with a calcium source concentration of 0.1 mol / L to 1.0 mol / L, wherein the calcium source is selected from one or more of calcium chloride, calcium nitrate, calcium acetate, and calcium lactate.

[0011] Secondly, based on the aforementioned restoration materials, this invention provides a method for in-situ stimulating indigenous microbial mineralization to restore and reinforce rock and soil sites, characterized by comprising the following steps: (1) Detection and analysis: Soil samples were collected from the rock and soil site to be restored and analyzed to determine the types of key mineralized microbial communities and basic soil properties. (2) Activation pretreatment: Prepare the corresponding activation solution according to the key mineralizing microbial community type determined in step (1), and apply it to the area to be repaired. At the same time, create suitable environmental conditions to activate and enrich the key mineralizing microbial community. (3) In-situ mineralization restoration: cementing solution is injected into the soil treated in step (2) to induce the activated key mineralizing microbial community to undergo mineralization reaction and generate precipitation, thereby realizing the restoration and reinforcement of the rock and soil site; (4) Maintenance: During and after the activation pretreatment and in-situ mineralization remediation, maintain the temperature and humidity conditions of the remediation area to facilitate the growth of microbial community and mineralization reaction.

[0012] Preferably, in step (1), the analysis includes microbial community analysis and basic soil property detection; the microbial community analysis is performed by high-throughput gene sequencing; the basic soil property detection includes at least the determination of moisture content and pH value.

[0013] Preferably, in step (1), the key mineralizing microbial community is selected from one or more mixed communities of urease-producing bacteria, denitrifying bacteria, and sulfate-reducing bacteria inherent in the soil.

[0014] Preferably, in step (2), the activation liquid is applied in different ways according to the degree of damage to the rock and soil site; wherein, grouting is used for micro-cracks, spraying is used for weathered and peeling areas, and a combination of masonry and infiltration grouting is used for severely collapsed areas.

[0015] Preferably, in step (2), the suitable environmental conditions include: temperature 25-35℃, pH value of activation solution 7-9, activation time of 24-72 hours, and control of aerobic or anaerobic environment according to the characteristics of key mineralizing microbial communities.

[0016] Preferably, in step (3), the cementing liquid is injected using the upper surface penetration method, that is, the cementing liquid is slowly and evenly penetrated into the soil from top to bottom by means of capillary force or micro-pressure gravity; and during the mineralization process, the cementing liquid is replenished in multiple rounds according to the soil moisture content monitoring.

[0017] Preferably, the method is applicable to the restoration of rock and soil sites with different dominant key mineralized microbial communities at different depths; specifically, for soil at different depths, an activation solution and a cementing solution matching the corresponding dominant microbial community are prepared for regional or phased restoration.

[0018] (III) Beneficial Effects Compared with the prior art, the present invention has the following significant advantages: (1) True in-situ and ecological compatibility: It makes full use of the inherent microbial resources of the site itself, without the need to introduce any exogenous microorganisms, thus completely avoiding biological competition, rejection reactions and potential ecological invasion risks, and preserving the original microbial ecosystem and historical information of the site to the greatest extent, perfectly matching the highest principles of cultural relic protection: "not changing the original state" and "minimal intervention".

[0019] (2) Excellent uniformity and depth of repair: Through a two-step strategy of "activation first, mineralization later", the indigenous functional microbial community is first allowed to proliferate and accumulate in situ and uniformly inside the soil, and then a calcium source is provided. This allows the subsequent mineralization reaction to occur simultaneously throughout the entire distribution range of the microbial community, and the generated calcium carbonate precipitate is more widely and uniformly distributed, which can effectively repair deep micro-cracks and surface weathering layers, and achieve overall reinforcement "from the inside out".

[0020] (3) High and stable repair efficiency: It specifically activates the native key mineralizing microbial community that has survived in the local environment and has the strongest adaptability, avoiding the problem of exogenous bacteria not adapting to the local environment. The activated microbial community has high activity and vigorous metabolism, and the mineralization efficiency is significant, stable and controllable.

[0021] (4) Good material compatibility and durability: The calcium carbonate precipitate induced by microorganisms has a chemical composition and crystal structure similar to the carbonates in cemented soil in nature. It has excellent physical and chemical compatibility with the soil of the site, is not prone to internal stress or interface peeling, and has better durability than many organic chemical materials.

[0022] (5) Environmentally friendly and highly universal: No harmful chemical reagents are used in the entire restoration process, and the final product is natural and harmless. By "testing first and then formulating" for different sites, this method can be flexibly adapted to various rock and soil sites with different geographical environments, different soil types, and different dominant microbial communities, and has wide universality.

[0023] (6) Flexible construction methods: Differentiated activation solution application and repair processes are provided for different diseases such as cracks, weathering, and collapse. These processes can be combined and applied according to the actual conditions of the site, making them highly practical. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the relevant performance test results in an embodiment of the present invention.

[0025] in, Figure 1 (a) A graph showing the increase in peak compressive stress of soil after activation and remediation by different microbial communities compared to the original soil. Figure 1 (b) is a graph showing the variation of bacterial mineralization precipitation in soil samples under different activation solution ratios (urea concentration, nutrient source concentration) and different soil moisture contents for urease-producing bacteria. Figure 1 (c) is a schematic diagram of the gene sequencing analysis results. The line graph on the left shows the abundance ranking curves of microbial species in soil samples from different treatment groups (the curve of the activation treatment group is shorter and steeper, indicating that the dominant bacterial community is highly enriched). The bar graph on the right shows the relative intensity comparison of key metabolic pathways (such as urea hydrolysis and denitrification) (significantly enhanced in the activation treatment group). Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. It should be understood that the following embodiments are only used to illustrate the present invention and are not intended to limit the entirety of the present invention. Other embodiments obtained by those skilled in the art based on these embodiments without creative effort are all within the protection scope of the present invention.

[0027] Example 1 This invention provides a method for in-situ stimulating indigenous microbial mineralization to remediate and reinforce rock and soil sites, characterized by comprising the following steps: Step S1: Detection and Analysis and Identification of Key Mineralizing Microbial Communities Collect representative soil samples from the site to be restored (collected in layers at different orientations and depths) and conduct two core analyses: (1) Microbial community analysis: Using technologies such as 16S rRNA gene high-throughput sequencing, the community structure and abundance of microorganisms in soil samples were analyzed, and the "key mineralizing microbial communities" with both high relative abundance and clear carbonate mineralization metabolic pathways (such as urea hydrolysis, denitrification, sulfate reduction, etc.) were screened out.

[0028] (2) Basic soil properties testing: Determine the basic physicochemical properties of the soil sample, including but not limited to moisture content, optimum moisture content, pH value, plastic limit, liquid limit, porosity, etc. The purpose of this step is to fully understand the current status of the "soil matrix" and "indigenous microorganisms" to provide a scientific basis for the precise preparation of the subsequent activation solution and the optimization of application conditions.

[0029] Step S2: Preparation of Activation Solution and Pretreatment for Activation Based on the key mineralizing microbial community types and their suitable metabolic environment determined in step S1, prepare corresponding special activation solutions.

[0030] Among them, one or more mixed groups of bacteria inherent in the soil with carbonate mineralization potential, such as urease-producing bacteria, denitrifying bacteria, and sulfate-reducing bacteria, are considered as key mineralizing microbial communities.

[0031] The activating solution is a solution used to specifically stimulate and promote the growth and reproduction of inherent key mineralizing microbial communities in soil samples from rock and soil archaeological sites. Its composition is precisely designed and formulated according to the metabolic type of the target key mineralizing microbial community, aiming to provide the specific nutrient substrates and suitable pH environment required for the rapid proliferation of this community, rather than a broad-spectrum nutrient agent.

[0032] (1) For urease-producing bacteria: the activation solution is an alkaline solution containing urea (as a substrate) and microbial nutrients (such as yeast extract, peptone, etc.) (pH is usually adjusted to 8-9).

[0033] (2) For denitrifying bacteria: the activation solution is an anaerobic culture medium containing nitrate (as an electron acceptor) and organic carbon sources (such as sodium acetate, glucose, etc.).

[0034] (3) For sulfate-reducing bacteria: the activation solution is an anaerobic culture medium containing sulfate (as an electron acceptor) and electron donors (such as sodium lactate, hydrogen, etc.).

[0035] Subsequently, based on the specific form (type and extent of damage) of the site's soil, the activating solution was applied in a differentiated manner: (1) For micro-cracks (e.g., 1-2 cm wide): use low-pressure grouting or drip injection to inject the activating liquid into the periphery and interior of the crack.

[0036] (2) For areas with surface weathering, peeling, and powdering: Apply the activating liquid evenly to the diseased surface by low-pressure spraying or brushing. This can be done in batches to ensure full saturation.

[0037] (3) For areas with severe collapse and missing soil: a combination of "masonry" and "penetration" is adopted. That is, firstly, the activation liquid is mixed with the same type of site soil to make "activated soil" for filling and masonry; then, the activation liquid is injected at the interface between the new and old soil to promote the activation and cementation of microorganisms in the interface area.

[0038] After the activating solution is applied, a targeted environment needs to be created in the treatment area. For example, a temporary humidity-controlled shed should be built to maintain the temperature at 25-35℃ and the humidity within a range conducive to microbial activity. Appropriate gas environment control can also be implemented based on the aerobic / anaerobic characteristics of the key mineralizing microbial communities (such as purging the anaerobic bacteria remediation area with nitrogen). This "activation and cultivation" phase usually lasts 24-72 hours, allowing the indigenous key mineralizing microbial communities to be fully activated and proliferate in large quantities.

[0039] Step S3: Cementing solution infiltration and in-situ mineralization remediation After the key mineralizing microbial communities are fully activated and enriched, a cementing solution is injected into the treatment area. The preferred method is top-surface infiltration, where the treatment surface is covered with water-conducting materials such as filter paper or non-woven fabric and connected to the cementing solution container. Capillary action and microgravity allow the cementing solution to slowly, evenly, and from top to bottom penetrate deep into the soil. This method effectively avoids the short-path flow and uneven distribution of the grout caused by pressure injection. The injection process can be carried out in multiple rounds, and the timing and amount of supplementary injection are guided by monitoring the soil moisture content to ensure that calcium ions fully contact the enriched microbial communities in the soil pores and undergo a mineralization reaction, generating calcium carbonate precipitates that fill the pores and fissures.

[0040] The cementing solution provides calcium ions for subsequent microbial mineralization and deposition reactions. Its calcium source concentration is typically controlled between 0.1 mol / L and 1.0 mol / L, and in preferred embodiments, it can be 0.1, 0.5, and 1.0 mol / L to ensure an effective supply of calcium ions while avoiding inhibition of microbial activity due to excessive concentration. The calcium source is selected from one or more of calcium chloride, calcium nitrate, calcium acetate, and calcium lactate.

[0041] Step S4: Maintenance and Stabilization Throughout the entire activation pretreatment (S2) and in-situ mineralization remediation (S3) process, and for a period afterward, the remediation area needs continuous maintenance to keep its temperature and humidity within a suitable range, avoiding sudden drying or freeze-thaw cycles that could damage the forming precipitate. Once the reaction is complete, the area can be slowly dried at room temperature or low temperature to further solidify and stabilize the generated calcium carbonate precipitate, ultimately completing the remediation and reinforcement.

[0042] Before implementing restoration, a detailed on-site investigation and assessment of the site must be conducted, and the operating procedures for cultural relic protection must be strictly followed. All restoration materials (activating solutions, cementing solutions) must undergo small-scale mixing and efficacy verification tests in the laboratory using soil samples from the site before use.

[0043] Experimental Example 1: Restoration of the weathered layer on the surface of a silty clay site rich in urease-producing bacteria (1) Sampling and Detection: Several soil samples were aseptically collected from the weathered and eroded area of ​​a silty clay site at a depth of 0-20 cm. One portion of the soil samples underwent high-throughput 16S rRNA gene sequencing. Bioinformatics analysis showed that *Bacillus pasteurellii* and other urease-producing bacteria were relatively abundant potential key mineralizing microbial communities. Another portion of the soil samples underwent soil property testing, revealing a plastic limit of 8.9%, a liquid limit of 16%, and a soil pH of 8.5-9.0 (slightly alkaline). In a small-scale laboratory test, the potential mineralization precipitation of the microbial community was determined by adjusting the soil moisture content and adding basic nutrient solution at different moisture contents. The results are as follows: Figure 1(b) The curves show that the mineralization potential is greatest when the soil moisture content is 10% (close to the optimum moisture content). Therefore, the activation solution was applied with a moisture content of 10% as the standard in the subsequent activation process. Other experiments were simplified and also used the optimum moisture content as the experimental condition.

[0044] (2) Preparation of Activation Solution: Based on the fact that the key mineralizing microbial community is urease-producing bacteria, an activation solution with urea as the main substrate was designed. Through indoor orthogonal experiments, the effects of different combinations of urea concentration and yeast extract (nutrient source) concentration on the amount of mineralized precipitation were tested (the results trend is shown in the figure). Figure 1 (b) As shown in the bar chart, the optimal ratio was determined to be: 1.5 mol / L urea and 10 g / L yeast extract. An additional 5 g / L ammonium sulfate was added to provide a nitrogen source and buffer the pH. Finally, the pH of the activating solution was adjusted to 9.0 with NaOH solution to match the alkaline soil environment and promote urease activity.

[0045] (3) Activation Pretreatment: A simple heat-insulating and humidity-controlled shed is built in the weathered area of ​​the site, with the temperature inside controlled at approximately 30°C and the humidity kept at a high saturation state to prevent excessive evaporation of surface moisture. A low-pressure spraying device is used to evenly spray the prepared activation solution onto the surface of the weathered soil layer until the target moisture content of approximately 10% is reached at a depth of approximately 2-3 cm below the surface and the soil is completely soaked. Spraying can be carried out in 2-3 intervals. After spraying, the environment inside the shed is maintained, and the soil is left to stand for 48 hours to allow the indigenous urease-producing bacteria to be specifically activated and multiply in large quantities.

[0046] (4) In-situ mineralization remediation: After activation and cultivation, a similar low-pressure spraying method was used to spray a 1.0 mol / L calcium acetate solution as a cementing agent into the treated area in four batches (once every 12 hours). The amount of each spray was determined so that no surface runoff occurred and the solution could slowly seep down. The entire process was carried out in a heat-insulated and humidity-controlled shed, with a total reaction time of approximately 48 hours.

[0047] (5) Curing and Effect Evaluation: After the cementitious liquid injection is completed, continue curing inside the greenhouse for 7 days, then remove the greenhouse structure and allow it to air dry naturally. After 7 days of curing, drill core samples from the repaired area for unconfined compressive strength testing. Figure 1 As shown in (a), the peak compressive stress of the repaired soil reached 129.4% of that of the undisturbed healthy soil. Simultaneously, permeability testing indicated that the impermeability of the repaired layer increased by an order of magnitude. Microscopic observation revealed that the pores and microcracks in the weathered layer were effectively filled with dense calcium carbonate crystals. Genetic sequencing was performed again on the repaired soil samples, and their species abundance curves (…) Figure 1 (c) The "short and steep" characteristic indicates a decrease in microbial community diversity, with urease-producing bacteria becoming the absolute dominant bacteria; metabolic pathway analysis ( Figure 1(d) shows that the strength of the urea hydrolysis metabolic pathway is significantly higher than that of the original soil, proving that the activation solution achieves "targeted activation and strong enrichment" of the target microbial community.

[0048] Experimental Example 2: Restoration of collapsed sections of a sandy soil archaeological site rich in denitrifying bacteria (1) Sampling and testing: Soil samples were collected from the periphery of a collapsed pit at a sandy soil site at a depth of 10-30 cm (representing the deep soil layer). Microbiological analysis showed that some denitrifying bacteria species in the genera *Denitrifying Bacillus* and *Pseudomonas* were key mineralizing microbial communities. Soil testing determined its basic properties (plastic limit 8.9%, liquid limit 16%, soil pH 8.3-9.0).

[0049] (2) Preparation of Activation Solution: The experiment was conducted following the steps in Example 1, and will not be described in detail here. The optimal moisture content (12.9%) was determined. Based on the anaerobic metabolic characteristics of denitrifying bacteria, an anaerobic activation solution was prepared. The optimal concentrations of potassium nitrate and sodium acetate were verified at the optimal moisture content. The final formula included: 10 g / L potassium nitrate (electron acceptor), 5 g / L sodium acetate (organic carbon source and electron donor), and 3 g / L peptone (compound nutrient source). After the solution was prepared, high-purity nitrogen gas was introduced for about 20 minutes to remove dissolved oxygen, and then it was sealed and stored.

[0050] (3) Activation Pretreatment: First, collect loose soil of the same texture around the site. Using this optimal moisture content (12.9%) as a benchmark, use the above-mentioned anaerobic activation liquid as mixing water and mix it thoroughly with the loose soil to prepare "activation treatment reserve soil". During the restoration construction, first perform low-pressure grouting on the exposed surfaces of the collapsed pit walls and bottom, and inject a small amount of the same anaerobic activation liquid to pre-activate the indigenous microbial community at the interface. Then, backfill and compact the "activation treatment reserve soil" in layers and perform masonry repair. Construct a heat-insulating and humidity-controlled shed above the treatment area and continuously introduce low-flow nitrogen gas into the shed to maintain a micro-anaerobic environment. Control the temperature inside the shed at 30℃ and let it stand for 72 hours.

[0051] (4) In-situ mineralization remediation: After activation and culture, the top surface capillary permeation method was used. Multiple layers of filter paper were laid flat on the surface of the remediation area, and a storage tank with small holes at the bottom was placed on the filter paper. The tank contained a 0.5 mol / L calcium nitrate solution (both calcium source and nitrate ions can participate in the metabolism of denitrifying bacteria) as a cementing solution. The cementing solution permeated downwards evenly and slowly through the capillary action of the filter paper. The cementing solution was replenished in 6 batches within 72 hours to ensure that the entire remediation was fully wetted. A constant temperature, humidity, and micro-anaerobic environment were maintained throughout the process.

[0052] (5) Maintenance and effect evaluation: Samples were taken for testing 7 days after maintenance. Figure 1As shown in (a), the peak compressive stress of the restored infill reached 126.78% of that of the original healthy soil. The restored structure was intact, tightly bonded to the original soil, and exhibited significantly improved resistance to disintegration. Gene sequencing analysis ( Figure 1 (c) also shows that the bacterial community is homogeneous, and metabolic pathway analysis ( Figure 1 (d) Metabolic pathways 4, 5, and 6 are all related to denitrification. The intensity of the direct pathway (4) was slightly increased compared to the undisturbed soil, while the intensity of the indirect pathways (5 and 6) was significantly increased, confirming the effectiveness of targeted activation.

[0053] Experimental Example 3: Comprehensive Restoration of Sites with Mixed Microbial Communities (1) Sampling and testing: A systematic grid sampling was conducted on a large earthen site (including different orientations, 0-10cm surface layer, 10-20cm middle layer, and 20-30cm deep layer). Comprehensive analysis revealed that: in the surface soil (0-10cm), due to contact with air, aerobic / facultative anaerobic urease-producing bacteria were the dominant mineralizing bacteria; while in the deep soil (20-30cm), due to the scarcity of oxygen, there were abundant anaerobic sulfate-reducing bacteria.

[0054] (2) Step-by-step activation and remediation: Given the differences in microbial communities and environment at different depths, a phased and regional remediation strategy was adopted. For parts not explicitly stated, adaptive adjustments were made according to the methods in Experimental Examples 1 and 2, such as determining specific conditions like pH and moisture content based on soil properties. Suitable activation solutions were prepared based on the optimal moisture content and key mineralizing microbial community types at different depths.

[0055] Surface weathering repair: Using the same method as in Example 1, urea-based activating solution and calcium acetate cementing solution were used to spray and activate and mineralize the surface weathering layer.

[0056] Deep fracture repair: For detected deep fractures, a method similar to that in Example 2 but targeting sulfate-reducing bacteria is employed. An anaerobic activating solution rich in sulfate and sodium lactate is prepared and injected into the deep fracture zone via micro-drilling grouting. Then, calcium chloride or calcium lactate cementing solution is injected, with the concentration adjusted as needed. During construction, care must be taken to seal the deep grouting holes, and temporary local anaerobic environment creation measures may be used as supplementary measures.

[0057] Through the above comprehensive approach, "precision medicine" style restoration was achieved for different disease characteristics and different microbial ecological sites of the same site (microbial indicators are shown in...). Figure 1 (c) The description of mixed bacteria demonstrates the high flexibility and adaptability of the method of the present invention.

[0058] Furthermore, the experimental examples of this invention mainly describe the case where a single key mineralizing microbial community is selected at the same depth. Communities with different key mineralizing microbial communities at different depths are considered mixed cultures. This is primarily because the relative abundance of microorganisms varies significantly at different depths, and the group with the highest abundance is selected. If multiple key mineralizing microbial communities have similar abundance at the same depth, a comprehensive approach can be taken, selecting an activation solution and a binding solution suitable for both mixed communities to achieve the best repair effect. For example, if both urease-producing bacteria and sulfate-reducing bacteria have high abundance at the same depth, the preparation of the activation solution should consider a culture medium that includes urea, yeast extract, sulfate, sodium lactate, etc., to accommodate both groups of bacteria.

[0059] It should be noted that the above embodiments are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention. For example, the type of nutrient source in the activation solution, the injection frequency and total amount of the cementing solution, and the specific temperature and humidity parameters for maintenance can all be adjusted according to the actual conditions of the specific site under the guidance of the above principles.

Claims

1. A method for in-situ stimulating indigenous microbial mineralization to remediate and reinforce rock and soil sites, characterized in that, Includes the following steps: (1) Testing and analysis: Soil samples were collected from the rock and soil site to be restored and analyzed to determine the types of key mineralized microbial communities and basic soil properties. (2) Activation pretreatment: Prepare the corresponding activation solution according to the key mineralizing microbial community type determined in step (1), and apply it to the area to be repaired. At the same time, create suitable environmental conditions to activate and enrich the key mineralizing microbial community. (3) In-situ mineralization restoration: cementing liquid is injected into the soil treated in step (2) to induce the activated key mineralizing microbial community to undergo mineralization reaction and generate precipitation, thereby realizing the restoration and reinforcement of the rock and soil site; (4) Maintenance: During and after the activation pretreatment and in-situ mineralization remediation, maintain the temperature and humidity conditions of the remediation area to facilitate the growth of microorganisms and the mineralization reaction.

2. The method as described in claim 1, characterized in that, In step (1), the analysis includes microbial community analysis and basic soil property detection; the microbial community analysis is performed by high-throughput gene sequencing; the basic soil property detection includes at least the determination of moisture content and pH value.

3. The method as described in claim 1, characterized in that, In step (1), the key mineralizing microbial community is selected from one or more mixed communities of urease-producing bacteria, denitrifying bacteria, and sulfate-reducing bacteria inherent in the soil.

4. The method as described in claim 1 or 3, characterized in that, In step (2), the activation solution is specifically formulated according to the metabolic type of the key mineralizing microbial community and is selected from any one or more of the following: (1) An activation solution for urease-producing bacteria, which is an alkaline solution containing urea and microbial nutrients; (2) Activation solution for denitrifying bacteria, anaerobic culture medium containing nitrate and organic carbon source; (3) Activation solution for sulfate-reducing bacteria, an anaerobic culture medium containing sulfate and electron donors.

5. The method as described in claim 1, characterized in that, In step (2), the activation liquid is applied in different ways according to the degree of damage to the rock and soil site; for micro cracks, grouting is used, for surface weathering and peeling areas, spraying is used, and for severely collapsed areas, a combination of masonry and infiltration grouting is used.

6. The method as described in claim 1, characterized in that, In step (2), the suitable environmental conditions include: temperature 25-35℃, pH value of activation solution 7-9, activation time of 24-72 hours, and control of aerobic or anaerobic environment according to the characteristics of key mineralizing microbial communities.

7. The method as described in claim 1, characterized in that, In step (3), the cementing solution is a solution with a calcium source concentration of 0.1 mol / L to 1.0 mol / L, and the calcium source is selected from one or more of calcium chloride, calcium nitrate, calcium acetate, and calcium lactate.

8. The method as described in claim 1, characterized in that, In step (3), the cementing liquid is injected using the upper surface penetration method, that is, the cementing liquid is slowly and evenly penetrated into the soil from top to bottom by means of capillary force or micro-pressure gravity; and during the mineralization process, the cementing liquid is replenished in multiple rounds according to the soil moisture content monitoring.

9. The method as described in claim 1, characterized in that, The method is applicable to the restoration of rock and soil sites with different dominant key mineralized microbial communities at different depths; specifically, for soil at different depths, an activation solution and a cementing solution that match the corresponding dominant microbial community are prepared for regional or phased restoration.

10. A material for in-situ stimulating indigenous microbial mineralization and remediation of rock and soil sites, characterized in that, include: Activation solution: A solution used to specifically activate the inherent key mineralizing microbial community in soil. Its composition is determined according to the metabolic type of the target key mineralizing microbial community and contains specific nutrient substrates required for the growth and reproduction of the community. Cementing solution: A solution that provides calcium ions for microbial mineralization deposition, with a calcium source concentration of 0.1 mol / L to 1.0 mol / L; The activation solution comprises a solution targeting any of the following key mineralizing microbial communities: (1) For urease-producing bacteria: an alkaline solution containing urea and microbial nutrients; (2) For denitrifying bacteria: anaerobic culture medium containing nitrates and organic carbon sources; (3) For sulfate-reducing bacteria: anaerobic culture medium containing sulfate and electron donors; The calcium source in the cementing solution is selected from one or more of calcium chloride, calcium nitrate, calcium acetate, and calcium lactate.

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