A method for disposing of longcheng site litter in semi-humid region soil

Abstract

This application relates to the field of earthen site protection and preventive conservation technology, specifically disclosing a method for disposing of litter from earthen Great Wall sites in semi-humid areas. The method first investigates the thickness, decomposition degree, and component mass ratio of litter by setting up monitoring plots, creating a graded disposal ledger. Then, differentiated cleaning is carried out according to thickness grade. The removed litter undergoes two-stage sieving to obtain three types of components. After stabilization treatment with indigenous Streptomyces, these components are combined with local fine sand, indigenous filamentous cyanobacteria, native site soil, and indigenous Bacillus powder to prepare three types of functional protective materials. These materials are applied to the top, facade, and base slope of the wall, along with a phased maintenance and dynamic control mechanism. This method can be applied to the daily preventive management of rammed earth Great Wall sites in semi-humid areas. It can achieve in-situ resource utilization of litter while controlling the risk of biological weathering, improving the erosion resistance and adaptability of the surface soil of the site. The overall operation is standardized and causes minimal disturbance to the site itself.

Description

Technical Field

[0001] This application relates to the field of earthen site protection and preventive protection technology, and more specifically, it relates to a method for disposing of debris from the earthen Great Wall site in a semi-humid area. Background Technology

[0002] The earthen Great Wall ruins are mostly constructed of rammed earth, resulting in poor surface soil stability and susceptibility to weathering and erosion caused by rainfall and biological activity. In the semi-humid region, vegetation thrives, and the plant litter accumulating on the surface of the ruins over the years has a dual impact on the soil: moderate litter cover can buffer raindrop impact and inhibit excessive evaporation of surface moisture, providing some ecological protection; however, excessive litter accumulation continuously increases soil moisture and nutrient levels, providing ample substrate for microbial activity and thus accelerating the biological weathering process.

[0003] Currently, the disposal of surface debris at earthen archaeological sites mostly involves simple cleaning followed by centralized transportation. While this method can directly reduce the organic matter load on the surface, the removed debris cannot be utilized in situ, making it difficult to improve the erosion resistance of the archaeological surface with organic matter components. At the same time, transportation and disposal also increase on-site operation and maintenance costs and the environmental impact of material transfer. How to achieve the rational in-situ utilization of debris while controlling the risk of biological weathering caused by debris, and improve the protective effectiveness of the archaeological surface, is a technical problem that needs to be solved in the preventive management of earthen archaeological sites. Summary of the Invention

[0004] To address the problems of existing technologies where litter disposal is simple and unscientific, and where the methods of cleaning and transporting litter cannot achieve reasonable in-situ utilization of litter while controlling the risk of biological weathering, and where the surface protection effectiveness of the site needs to be improved, this application provides a method for disposing of litter from the Great Wall site in a semi-humid area.

[0005] A method for disposing of debris from the Great Wall ruins in a semi-humid area includes the following steps:

[0006] S1. Investigation and assessment: Fixed monitoring plots are set up at set intervals in the target site area. The thickness of the litter is measured in each plot to determine the degree of litter decomposition. The coverage of biological crust and the distribution of surface soil diseases are recorded. The mass ratio of undecomposed components to semi-decomposed components in the litter to be removed is determined to form a graded disposal ledger.

[0007] S2. Cleaning and sorting: Based on the graded disposal ledger, differentiated cleaning is carried out according to the thickness of the fallen material. At the same time, the removed fallen material is screened on site to separate three components: undecomposed dead branches and leaves, semi-decomposed humus, and fully decomposed humus mud. All components are retained within the site protection area throughout the process.

[0008] S3. Maturation and Stabilization and Preparation: Based on the mass ratio of undecomposed components to semi-decomposed components determined in step S1, the spraying amount and settling time of the indigenous Streptomyces actinomycete suspension were adjusted to mature and stabilize the semi-decomposed humic matter and the fully decomposed humic mud. Then, based on the three types of litter components, local fine sand, indigenous filamentous cyanobacteria, original soil of the site and indigenous Bacillus powder were respectively combined to prepare three types of functional protective materials: slope foot flexible buffer filler, algal humic composite inoculum, and surface crust base slurry.

[0009] S4. Protection and Construction: Functional materials are applied to the three areas of the city wall: top, facade, and base slope. The top of the city wall is covered with a surface crust base slurry and an algal humus composite inoculum. The facade is covered with a diluted surface crust base slurry and a suspension of native filamentous blue-green algae. The base slope is covered with a flexible buffer filler to complete the surface protection system.

[0010] S5. Maintenance and Control: Implement phased water replenishment and maintenance, and simultaneously measure the crust coverage rate and litter mass ratio during the annual operation period, and adjust the cleaning threshold and the output ratio of the three types of functional protective materials in a coordinated manner.

[0011] By adopting the above-mentioned technical solutions, a complete technical system has been established, encompassing investigation and assessment, graded disposal, screening and recycling, composting and stabilization, zoned protection, and dynamic regulation. Addressing the dual characteristics of litter at the semi-humid Great Wall site—both ecological protection and biological weathering risks—this system breaks through the traditional single-disposal model of clearing and transporting litter. While retaining a thin layer of litter with protective functions, the removed litter is classified and recycled according to its degree of decomposition. After composting and stabilization, easily decomposable organic matter is transformed into stable humus components, which are then used to prepare protective materials with different functions and backfilled into the corresponding areas of the site. This eliminates the hidden dangers of excessive moisture accumulation, excessive microbial proliferation, and aggravated organic acid erosion caused by excessively thick litter. Furthermore, the stabilized organic matter provides nutrients and an attachment carrier for the development of surface biological crusts, enhancing the soil's resistance to erosion. Combined with an annual dynamic regulation mechanism, this forms an adaptive closed-loop management system, meeting the refined and long-term needs of preventative protection for earthen sites.

[0012] Preferably, in step S1, the spacing between the monitoring plots is 50m to 100m, and the area of ​​a single plot is 1m²; the thickness of the litter is measured using the five-point method, and the accuracy of the measuring tool is not less than 0.1cm; the degree of litter decomposition is determined by visual inspection and tactile inspection, and is divided into three levels: undecomposed, semi-decomposed, and fully decomposed; the mass ratio is determined by random sampling, sorting, and weighing.

[0013] By adopting the above technical solutions, standardized quadrat layout and multi-dimensional survey methods can ensure the representativeness and accuracy of basic data, providing a reliable quantitative basis for subsequent graded disposal. The graded determination of the degree of decomposition of litter can intuitively distinguish the physicochemical characteristics and decomposition potential of the material. Combined with the quantitative determination of component mass ratio, it can provide data support for the precise adjustment of subsequent composting process parameters. The graded disposal ledger can realize standardized management of the entire process, ensure the consistency and traceability of disposal strategies in different sections, and meet the archival management requirements of cultural heritage protection.

[0014] Preferably, in step S2, the differentiated cleaning is performed according to the following rules: debris with a thickness ≤ 2cm is retained in situ; debris with a thickness of 2cm to 5cm is partially removed, with a final retention thickness of 1.5cm to 2cm; debris with a thickness ≥ 5cm is thoroughly removed by peeling it off layer by layer from top to bottom until the original rammed soil surface is exposed, with a single cleaning thickness of 3cm to 5cm; the retention thickness of debris in the area surrounding the disease is reduced to 1.2cm to 1.8cm; the cleaning operation is carried out using a soft brush and a wind-powered blowing device, with the blowing air pump pressure ≤ 0.3MPa, and hard metal tools are prohibited.

[0015] By adopting the above technical solutions, a three-level differentiated cleaning is carried out based on the thickness of the fallen material. An intervention strategy is formulated based on the balance between the anti-corrosion benefits and weathering risks of the fallen material at different thicknesses. The thin layer can fully utilize its natural protective functions of buffering raindrop kinetic energy, inhibiting surface moisture evaporation, and regulating soil temperature. The middle layer can be moderately removed while preserving basic protective functions and reducing the hidden dangers of continuous high humidity and excessive microbial activity. The thick layer can be peeled off in layers to completely eliminate the risk of biological weathering caused by deep organic matter. With the help of soft tools and low-pressure purging, the mechanical disturbance to the original rammed soil surface can be minimized during the cleaning process. The reduced retention thickness around the diseased area also facilitates subsequent disease investigation and repair work.

[0016] Preferably, in step S2, the on-site screening adopts a two-stage screening process: firstly, the material is screened through a screen with an aperture of 0.8cm to 1.2cm for the first stage screening, and the material on the screen is undecomposed dead branches and leaves; then, the material under the screen is screened through a screen with an aperture of 0.15cm to 0.25cm for the second stage screening, and the material on the screen is semi-decomposed humus, while the material under the screen is fully decomposed humus mud.

[0017] By adopting the above technical solution, the removed debris can be accurately separated according to the degree of decomposition and particle size through two-stage screening. Materials at different decomposition stages have significant differences in physical structure, chemical composition and decomposition rate. Mixing them will lead to uneven performance fluctuations in protective materials. After grading, different components can be matched with the material preparation requirements of corresponding functions. Undecomposed components have good structural toughness and can be used as buffer skeleton materials. Semi-decomposed components have a moderate degree of humification and can be used as carrier substrates for microbial colonization. Fully decomposed components have a fine texture and can be used for soil surface improvement. Graded utilization can give full play to the functional value of various components and improve the performance adaptability and stability of protective materials.

[0018] Preferably, in step S3, the concentration of the indigenous Streptomyces actinomycete suspension is 1×10⁻⁶. 7 CFU / mL to 1×10 9 CFU / mL; when the mass ratio of the undecomposed component to the semi-decomposed component is greater than 1.5, the amount of bacterial suspension sprayed is 55 mL to 65 mL per kilogram of dry material, and the sealing and standing time is 55 h to 65 h; when the mass ratio is not greater than 1.5, the amount of bacterial suspension sprayed is 45 mL to 55 mL per kilogram of dry material, and the sealing and standing time is 42 h to 54 h; the maturity stability endpoint is when the material has no putrid odor.

[0019] By adopting the above technical solution, the composting treatment is carried out using indigenous Streptomyces actinomycetes. The strains are derived from the local soil environment and will not cause interference from alien species to the original micro-ecology of the site. The actinomycetes can directionally decompose the easily degradable organic components in the litter, promote the transformation of unstable organic matter into stable humic components, and significantly reduce the risk of microbial proliferation and concentrated release of organic acids in the short term after material backfilling. The amount of bacterial solution and the settling time can be dynamically adjusted according to the mass ratio of undecomposed and semi-decomposed components, which can adapt to the composting requirements of different material compositions and ensure uniform and stable composting degree. Using sensory indicators as the endpoint judgment basis also facilitates quick judgment by field workers and is suitable for the working conditions at the site.

[0020] Preferably, in step S3, the preparation rules for the three types of functional protective materials are as follows:

[0021] The flexible buffer filler at the toe of the slope is made by mixing undecomposed dead branches and leaves with local fine sand at a dry weight ratio of 2.5:7 to 3.5:7, with the dead branches and leaves cut to a length of 2cm to 3cm.

[0022] The algal humus composite inoculum is made by mixing semi-decomposed humus that has been decomposed and stabilized with native filamentous cyanobacteria of the genus Nostoc at a dry weight ratio of 4:1 to 6:1, and the moisture content of the material is controlled at 22% to 28%.

[0023] The surface crust base slurry is made by mixing fully decomposed humic mud that has been decomposed and stabilized with the original soil of the site at a dry weight ratio of 0.8:9 to 1.2:9, and the amount of indigenous Bacillus subtilis powder added is 0.08‰ to 0.12‰ of the total dry material weight.

[0024] By adopting the above technical solutions, the three types of functional protective materials are respectively matched with the main erosion control factors and protection needs of different areas of the site. In the flexible buffer filler at the slope toe, undecomposed dead branches and leaves can form a flexible skeleton to reduce the scouring energy of raindrops and runoff, and local fine sand can improve the water permeability and air permeability of the filler, avoiding water from staying at the foundation for a long time and softening the soil. The two work together to achieve a balance between erosion prevention and water conduction. In the algal humus composite inoculation material, the decomposed semi-decomposed humus can provide slow-release nutrients and a loose attachment matrix for filamentous cyanobacteria, avoiding nutrient deficiency or water loss and death of cyanobacteria from direct contact with bare soil, and improving the colonization and survival rate of algal cells. In the surface crust base slurry, fully decomposed humus mud can improve the pore structure of the original surface soil, and indigenous Bacillus subtilis can secrete extracellular polymers to promote soil particle aggregation and improve the structural stability of the surface soil. The three types of materials work together to construct a comprehensive surface protection system.

[0025] Preferably, in step S4, the construction process for the thick layer removal area on the top of the city wall is as follows: first, a soft scraper is used to lightly press the surface soil along the tangent direction of the soil surface, and simultaneously, a mist spray of clean water is used to wet the surface soil to a depth of 0.3mm to 0.5mm; then, a surface crust base slurry is sprayed at a rate of 1.0kg / m². 2 Up to 1.4 kg / m 2 Lightly rake the surface layer to a depth of 0.8mm to 1.2mm to allow the slurry to blend with the original soil; after the surface is semi-dry, spread algae-humus composite inoculum to a thickness of 1mm to 2mm, and spray clean water until the soil surface is saturated but does not produce runoff.

[0026] By adopting the above technical solution and a layered construction process, the surface soil is first lightly pressed and moistened to consolidate the surface loose soil and form a smooth bonding interface, avoiding soil particle splashing or slurry loss during subsequent slurry spraying. After spraying the base slurry, it is lightly raked to integrate, allowing the modified material to form a gradual transition layer with the original soil, avoiding obvious interface delamination and reducing the risk of protective layer peeling under wet-dry cycles. After the base is semi-dry, the inoculum is spread and water is sprayed to activate algal cell activity. With the help of a soft brush, the algal cells are embedded in the gaps between soil particles, improving adhesion. The step-by-step construction ensures the bonding strength of each layer and improves the structural stability of the overall protective layer.

[0027] After removing thick layers of debris, the exposed surface of the original rammed earth often contains loose soil and micro-cracks. Applying a soft scraper with gentle tangential pressure can re-compact the loose surface soil particles without altering the original pore structure, creating a smooth and well-bonded base interface. This process provides a good adhesion foundation for subsequent grout application, preventing problems such as poor bonding and drying shrinkage cracking caused by directly spraying grout onto loose soil.

[0028] Preferably, in step S4, the loose areas of the city wall facade disease are treated using a three-step spraying process: the first application is atomized spraying of diluted surface crust base slurry, with a soil-to-mud dry mass ratio of 14:1 to 16:1; when the base is semi-dry, a suspension of indigenous Nostoc filamentous cyanobacteria is sprayed at a concentration of 5×10⁻⁶. 5 cells / mL up to 1.5 × 10⁻⁶ 6 cells / mL; third application of extremely diluted compost slurry; air pump pressure ≤0.2MPa for spraying operation.

[0029] By adopting the above technical solution, a three-step spraying process is used to address the characteristics of weak adhesion and susceptibility to erosion of the city wall facade soil. The first step involves spraying a diluted base slurry, which forms an adhesive base on the facade and fills micropores, improving the adhesion of subsequent materials. The second step involves spraying a cyanobacteria suspension, which allows functional algal cells to be evenly colonized on the base. The third step involves spraying an extremely diluted humic mud slurry, which forms a thin protective film to reduce the erosion and loss of cyanobacteria by rainfall, while maintaining air permeability and light transmission so as not to affect the growth of cyanobacteria. The entire process is carried out using low-pressure spraying, which can avoid erosion and damage to the original rammed earth structure of the facade caused by high-pressure airflow, in line with the principle of minimal disturbance in the protection of earthen ruins.

[0030] Preferably, in step S4, flexible buffer filler is laid horizontally in the slope toe area of ​​the wall foundation, with a thickness of 1.0cm to 1.5cm.

[0031] By adopting the above technical solution, a continuous protective buffer zone can be formed by horizontally laying buffer filler in the slope toe area of ​​the wall foundation. This effectively reduces the splashing energy of raindrops and the scouring force of surface runoff, and reduces the erosion damage of water flow to the wall foundation soil. The appropriate laying thickness can ensure the buffer protection effect while avoiding excessive water retention in the filler and infiltration that erodes the rammed earth of the wall foundation. It takes into account both the protective function and humidity control, and is suitable for the environmental characteristics of runoff collection and strong erosion in the wall foundation area.

[0032] Preferably, in step S5, the phased water replenishment and maintenance cycle is 3 to 5 weeks. For the first 2 weeks, only clean water is sprayed at night, with the water replenishment endpoint being when the soil surface reaches saturation but no runoff occurs. Afterward, the frequency of water replenishment is gradually reduced until artificial water replenishment is stopped. The annual operation period is from November to January of the following year. If the crust coverage rate is not less than 60%, the litter thickness removal threshold is increased by 0.4 cm to 0.6 cm, and the output ratio of flexible buffer filler at the slope toe is increased, while the ratio of algal humus composite inoculum and surface crust base slurry is reduced. If the crust coverage rate is less than 30%, the litter thickness removal threshold is decreased by 0.4 cm to 0.6 cm, and the output ratio of the three types of materials is adjusted in the opposite direction.

[0033] By adopting the above technical solutions, phased nighttime water replenishment can provide suitable moisture conditions in the early stage of cyanobacteria colonization. Nighttime spraying results in low evaporation loss and high water utilization efficiency. At the same time, it avoids the damage to the soil structure caused by excessively rapid alternation between dry and wet conditions under high daytime temperatures. Gradually reducing the frequency of water replenishment in the later stages allows the protection system to gradually adapt to natural precipitation conditions, improving the system's natural stability. The annual dynamic control mechanism can adjust the subsequent treatment strategy in reverse according to the actual crust development effect. When crust development is good, the litter removal threshold can be appropriately relaxed to give full play to the natural protective role of litter. When crust development is insufficient, the removal threshold can be lowered and the material ratio can be adjusted to enhance the crust-promoting effect, forming a long-term adaptive closed-loop management system that adapts to the changing environmental conditions of the site year by year.

[0034] In summary, this application has the following beneficial effects:

[0035] 1. Because this application adopts a treatment system that combines graded cleanup with in-situ resource utilization, the cleared debris is classified and recycled according to its degree of decomposition. After being decomposed and stabilized, functional protective materials are prepared in a targeted manner and backfilled into the corresponding areas. This replaces the traditional single mode of cleanup and transportation. It can reduce the risk of biological weathering caused by excessive debris, while improving the erosion resistance of the surface soil, forming a complete closed loop of treatment and protection, which is suitable for the management and maintenance needs of the Great Wall site in the semi-humid area.

[0036] 2. In this application, native Streptomyces actinomycetes are preferred for composting and stabilization treatment. The amount of bacterial solution and the settling time are dynamically adjusted according to the mass ratio of litter components. This can promote the transformation of easily decomposed organic matter into stable humus, reduce the risk of concentrated release of organic acids and excessive microbial activity after material backfilling, and at the same time reduce the interference of foreign species on the original micro-ecology of the site, ensuring the uniformity of the performance of protective materials.

[0037] 3. The method of this application matches the corresponding functional materials and construction technology for the erosion characteristics of three types of areas: the top of the city wall, the facade of the city wall, and the foot of the wall foundation. The top adopts layered construction to strengthen the bonding force of the base, the facade adopts three-step spraying to improve the adhesion stability, and the wall foundation is laid with buffer filler to reduce runoff erosion. This can improve the targeting of protective measures and enhance the comprehensive erosion resistance of the surface of the site.

[0038] 4. In this application, the preferred management model is a phased nighttime water replenishment and maintenance combined with annual dynamic control. Initial water replenishment ensures the efficiency of biological crust colonization, and in the later stage, the cleaning threshold and material ratio are adjusted in reverse according to the crust coverage rate. This model can adapt to the changing natural environmental conditions of the site from year to year, achieve long-term adaptive management, and improve the long-term operational stability of the protection system. Attached Figure Description

[0039] Figure 1 This is a flowchart of a method for disposing of litter from a semi-humid Great Wall site, as provided in this application.

[0040] Figure 2 This is a comparison diagram of the soil physicochemical properties after thin-layer litter treatment in the various embodiments and comparative examples provided in this application;

[0041] Figure 3 This is a comparison diagram of the soil physicochemical properties after treatment of middle layer litter in the various embodiments and comparative examples provided in this application;

[0042] Figure 4 This is a comparison diagram of the soil physicochemical properties after treatment of thick litter layers in the various embodiments and comparative examples provided in this application;

[0043] Figure 5 This is a comparison chart of the biological crust coverage test results of different treatment schemes in the embodiments and comparative examples provided in this application. Detailed Implementation

[0044] The present application will be further described in detail below with reference to embodiments and comparative examples. Unless otherwise specified, the experimental methods used below are conventional methods. Unless otherwise specified, the materials, reagents, methods and instruments used are all conventional materials, reagents, methods and instruments in the art, which can be obtained by those skilled in the art through commercial channels or prepared according to literature methods.

[0045] Technical Concept: Existing technologies for handling litter at the Great Wall site primarily focus on thickness-based grading and removal. The core idea is to reduce the surface organic matter load by removing excessive litter, thereby mitigating the risk of bioweathering. However, these technologies only treat the removed litter as waste for off-site disposal, failing to differentiate and utilize litter components at different decomposition levels. This results in a waste of in-situ organic resources and makes it difficult to leverage the modifying effect of organic matter to improve the structural stability and erosion resistance of the site's surface soil. The overall treatment approach is relatively simplistic, and there is room for improvement in comprehensive protective effectiveness.

[0046] This technical solution first clarifies the thickness and composition characteristics of litter through standardized quadrat surveys, establishes a graded disposal ledger, and then performs thickness-differentiated cleaning. The removed litter is then screened and classified in two stages. Next, indigenous Streptomyces actinomycetes are used to mature and stabilize the semi-decomposed and fully decomposed components. The three types of components are then directionally prepared into functional protective materials suitable for different areas, which are backfilled into the corresponding parts of the city wall in different zones. A phased maintenance and annual dynamic control mechanism is also provided to control the risk of biological weathering while realizing the in-situ resource utilization of litter and improving the comprehensive protective effectiveness of the site surface.

[0047] Example 1: This example provides a method for disposing of litter from the Great Wall ruins in a semi-humid area, including the following steps:

[0048] S1. Investigation and Assessment: Fixed monitoring plots are set up at set intervals in the target site area. The thickness of the litter is measured in each plot to determine the degree of litter decomposition. The coverage rate of biological crust and the distribution of surface soil diseases are recorded. The mass ratio of undecomposed components to semi-decomposed components in the litter to be removed is determined to form a graded disposal ledger.

[0049] The monitoring plots were spaced 75m apart, with each plot measuring 1m². The thickness of the litter was measured using a five-point method with a precision of 0.1cm. The degree of litter decomposition was determined visually and by touch, categorized into three levels: undecomposed, partially decomposed, and fully decomposed. The mass ratio was determined by random sampling and weighing. Each plot was secured at its four corners with PVC pipes, labeled with a unique number, and its GPS coordinates were recorded. All baseline data was collected within one week prior to disposal to ensure the data accurately reflected the true depositional state of the surface litter at the site.

[0050] S2. Cleaning and sorting: Based on the graded disposal ledger, differentiated cleaning is carried out according to the thickness of the fallen material. At the same time, the removed fallen material is screened on site to separate three components: undecomposed dead branches and leaves, semi-decomposed humus, and fully decomposed humus mud. All components are retained within the site protection area throughout the process.

[0051] The differentiated cleaning process is implemented according to the following rules: Debris ≤2cm thick is retained in situ; debris 2cm to 5cm thick is partially removed, with a final retention thickness of 1.75cm; debris ≥5cm thick is thoroughly removed by layering from top to bottom until the original rammed soil surface is exposed, with a single cleaning thickness of 4cm; the retention thickness of debris in the surrounding area of ​​the disease is reduced to 1.5cm. The cleaning operation uses ultra-fine nylon soft brushes in conjunction with a pneumatic blowing device. The soft brush bristles are 0.08mm in diameter and 2.5cm long, with no hard core in the brush head. The blowing air pump pressure is 0.3MPa, and hard metal tools are prohibited. On-site screening employs a two-stage screening process: first, the material is screened through a 1.0cm aperture screen, with the oversize material being undecomposed dead branches and leaves; the undersize material is then screened through a 0.2cm aperture screen, with the oversize material being semi-decomposed humus and the undersize material being fully decomposed humus mud. The screening process is carried out manually with reciprocating screening, with each screening session lasting 3 minutes. Screening proceeds from top to bottom, passing the material through each stage to avoid material breakage and alteration of particle size distribution. The cleaning operation proceeds unidirectionally along the drainage direction to prevent debris from falling into the gaps of the damaged area and to minimize disturbance to the original rammed soil.

[0052] S3. Maturation, Stabilization and Preparation: Based on the mass ratio of undecomposed to semi-decomposed components determined in step S1, the spraying dosage and settling time of the indigenous Streptomyces actinomycete suspension were adjusted to mature and stabilize the semi-decomposed humic material and the fully decomposed humic mud. Then, based on the three types of litter components, local fine sand, indigenous filamentous cyanobacteria, original soil of the site and indigenous Bacillus powder were respectively combined to prepare three types of functional protective materials: slope foot flexible buffer filler, algal humic composite inoculum, and surface crust base slurry.

[0053] Among them, the concentration of indigenous Streptomyces actinomycete suspension was 1×10⁻⁶. 8 CFU / mL; when the mass ratio of undecomposed components to semi-decomposed components is greater than 1.5, the application rate of bacterial suspension is 60 mL per kilogram of dry material, and the sealed covering and standing time is 60 h; when the mass ratio is not greater than 1.5, the application rate of bacterial suspension is 50 mL per kilogram of dry material, and the sealed covering and standing time is 48 h; the maturity and stability endpoint is when the material has no putrid odor. During the spraying of bacterial suspension, the material is stirred at a uniform speed of 60 r / min to ensure that the bacterial solution and material are mixed evenly. The covering uses a breathable and impermeable membrane, and the standing temperature is maintained at 15-25℃. The preparation rules for the three types of functional protective materials are as follows:

[0054] The flexible buffer filler at the foot of the slope is made by mixing undecomposed dead branches and leaves with local fine sand at a dry weight ratio of 3:7. The length of the dead branches and leaves is 2.5cm. During mixing, a horizontal mixing device is used to mix at 80r / min for 12min. After mixing, the material is naturally air-dried until the moisture content is 15% for later use.

[0055] The algal humus composite inoculum is made by mixing semi-decomposed humus that has been stabilized and matured with native filamentous cyanobacteria of the genus Nostoc at a dry weight ratio of 5:1, with the material moisture content controlled at 25%. The mixing process is carried out by low-speed and gentle stirring, with the speed controlled at 40 r / min and the stirring time at 8 min, to avoid damaging the activity of algal cells.

[0056] The surface crust base slurry is made by mixing fully decomposed humus mud and native soil of the site at a dry weight ratio of 1:9. The amount of indigenous Bacillus subtilis powder added is 0.1‰ of the total dry material weight. When mixing, add an appropriate amount of water to adjust it to a sprayable slurry, stir at a stirring speed of 100 r / min, and stir for 15 minutes until the material is uniform and free of lumps.

[0057] S4. Protection and Construction: Functional materials are applied to the three areas of the city wall: top, facade, and base slope. The top of the city wall is covered with a surface crust base slurry and an algal humus composite inoculum. The facade is covered with a diluted surface crust base slurry and a suspension of native filamentous blue-green algae. The base slope is covered with a flexible buffer filler to complete the surface protection system.

[0058] The construction process for the thick layer removal area on the top of the city wall is as follows: First, use a soft scraper to lightly press the surface soil along the tangent direction of the soil surface, and simultaneously spray clean water to moisten the surface soil to a depth of 0.4mm; then spray a surface crust base slurry at a rate of 1.2kg / m², and lightly rake the surface to a depth of 1.0mm to allow the slurry to integrate with the original soil; after the surface is semi-dry, spread algae-humus composite inoculum at a thickness of 1.5mm, and spray clean water until the soil surface is saturated but without generating runoff. A low-pressure sprayer with a nozzle diameter of 0.6mm is used for spraying. After spraying the cyanobacteria-related materials, gently comb the soil surface with a soft brush to promote contact between the cyanobacteria and the soil, improving the planting efficiency.

[0059] The loose areas of the city wall facade were treated with a three-step spraying process: the first layer was atomized spraying of diluted surface crust base slurry, with a soil-to-mud dry weight ratio of 15:1; when the base was semi-dry, a suspension of indigenous Nostoc filamentous cyanobacteria was sprayed at a concentration of 1×10⁻⁶. 6 cells / mL; the third spray uses an extremely diluted concentration of compost slurry; the air pump pressure for spraying is 0.2 MPa. During spraying, the nozzle should be kept 40 cm away from the vertical surface and moved horizontally at a uniform speed to avoid local material accumulation and erosion of the soil.

[0060] Flexible buffer filler material with a thickness of 1.2cm is laid horizontally at the toe of the wall foundation slope. After laying, the surface of the filler material is gently patted to ensure that the filler material is in close contact with the slope soil, which can effectively buffer raindrop splash erosion and reduce surface runoff erosion.

[0061] S5. Maintenance and Control: Implement phased water replenishment and maintenance, and simultaneously measure the crust coverage rate and litter mass ratio during the annual operation period, and adjust the cleaning threshold and the output ratio of the three types of functional protective materials in a coordinated manner.

[0062] The phased water replenishment and maintenance cycle is 4 weeks. For the first 2 weeks, only clean water is sprayed at night, with the water replenishment ending when the soil surface reaches saturation but no runoff occurs. Afterwards, the frequency of water replenishment is gradually reduced until manual water replenishment is stopped. The annual operation period is from November to January of the following year. If the crust coverage rate is not less than 60%, the litter thickness removal threshold is increased by 0.5cm, and the output ratio of flexible buffer filler at the slope toe is increased, while the ratio of algal humus composite inoculum and surface crust base slurry is reduced. If the crust coverage rate is less than 30%, the litter thickness removal threshold is decreased by 0.5cm, and the output ratio of the three types of materials is adjusted in the opposite direction. Nighttime spraying is carried out from 10 PM to 5 AM the next day, with each spraying lasting 8 minutes. Atomized spraying is used to avoid impacting the surface soil. Personnel are prohibited from stepping on the work area during the maintenance period.

[0063] Example 2: This example provides a method for disposing of litter from the Great Wall ruins in a semi-humid area, including the following steps:

[0064] S1. Investigation and Assessment: Fixed monitoring plots are set up at set intervals in the target site area. The thickness of the litter is measured in each plot to determine the degree of litter decomposition. The coverage rate of biological crust and the distribution of surface soil diseases are recorded. The mass ratio of undecomposed components to semi-decomposed components in the litter to be removed is determined to form a graded disposal ledger.

[0065] The monitoring plots were spaced 50 meters apart, with each plot measuring 1 m². The thickness of the litter was measured using a five-point method with a precision of 0.1 cm. The degree of litter decomposition was determined visually and by touch, categorized into three levels: undecomposed, partially decomposed, and fully decomposed. The mass ratio was determined by random sampling, sorting, and weighing. Each plot was secured at its four corners with PVC pipes, labeled with a unique number, and its GPS coordinates were recorded. All baseline data was collected within one week prior to disposal to ensure the data accurately reflected the true depositional state of the surface litter at the site.

[0066] S2. Cleaning and sorting: Based on the graded disposal ledger, differentiated cleaning is carried out according to the thickness of the fallen material. At the same time, the removed fallen material is screened on site to separate three components: undecomposed dead branches and leaves, semi-decomposed humus, and fully decomposed humus mud. All components are retained within the site protection area throughout the process.

[0067] The differentiated cleaning process is implemented according to the following rules: Debris with a thickness ≤2cm is retained in situ; debris with a thickness of 2cm to 5cm is partially removed, with a final retention thickness of 1.5cm; debris with a thickness ≥5cm is thoroughly removed by layering from top to bottom until the original rammed soil surface is exposed, with a single cleaning thickness of 3cm; the retention thickness of debris in the surrounding area of ​​the disease is reduced to 1.2cm. The cleaning operation uses ultra-fine nylon soft brushes in conjunction with a pneumatic blowing device. The soft brush bristles are 0.07mm in diameter and 2cm long, with no hard core in the brush head. The blowing air pump pressure is 0.3MPa, and hard metal tools are prohibited. On-site screening employs a two-stage screening process: the first stage screening uses a 0.8cm aperture screen, with the oversize material being undecomposed dead branches and leaves; the undersize material then undergoes a second stage screening using a 0.15cm aperture screen, with the oversize material being semi-decomposed humus and the undersize material being fully decomposed humus mud. The screening process is carried out manually with reciprocating screening, with each screening session lasting 2 minutes. Screening proceeds from top to bottom, passing the material through each stage to avoid material breakage and alteration of particle size distribution. The cleaning operation proceeds unidirectionally along the drainage direction to prevent debris from falling into the gaps of the damaged area and to minimize disturbance to the original rammed soil.

[0068] S3. Maturation, Stabilization and Preparation: Based on the mass ratio of undecomposed to semi-decomposed components determined in step S1, the spraying dosage and settling time of the indigenous Streptomyces actinomycete suspension were adjusted to mature and stabilize the semi-decomposed humic material and the fully decomposed humic mud. Then, based on the three types of litter components, local fine sand, indigenous filamentous cyanobacteria, original soil of the site and indigenous Bacillus powder were respectively combined to prepare three types of functional protective materials: slope foot flexible buffer filler, algal humic composite inoculum, and surface crust base slurry.

[0069] Among them, the concentration of indigenous Streptomyces actinomycete suspension was 1×10⁻⁶. 7 CFU / mL; when the mass ratio of undecomposed components to semi-decomposed components is greater than 1.5, the application rate of bacterial suspension is 55 mL per kilogram of dry material, and the sealed covering and standing time is 55 h; when the mass ratio is not greater than 1.5, the application rate of bacterial suspension is 45 mL per kilogram of dry material, and the sealed covering and standing time is 42 h; the maturity and stability endpoint is when the material has no putrid odor. During the spraying of bacterial suspension, the material is stirred at a uniform speed of 50 r / min to ensure that the bacterial solution and material are mixed evenly. The covering uses a breathable and impermeable membrane, and the standing temperature is maintained at 15-25℃. The preparation rules for the three types of functional protective materials are as follows:

[0070] The flexible buffer filler at the foot of the slope is made by mixing undecomposed dead branches and leaves with local fine sand at a dry weight ratio of 2.5:7. The dead branches and leaves are cut to a length of 2cm. During mixing, a horizontal mixing device is used to mix at 70r / min for 10min. After mixing, the material is naturally air-dried until the moisture content is 15% for later use.

[0071] The algal humus composite inoculum is made by mixing semi-decomposed humus that has been stabilized and matured with native filamentous cyanobacteria of the genus Nostoc at a dry weight ratio of 4:1, with the material moisture content controlled at 22%. The mixing process is carried out by low-speed and gentle stirring, with the speed controlled at 30 r / min and the stirring time at 6 min, to avoid damaging the activity of algal cells.

[0072] The surface crust base slurry is made by mixing fully decomposed humus mud and native soil of the site at a dry weight ratio of 0.8:9. The amount of indigenous Bacillus subtilis powder added is 0.08‰ of the total dry material weight. When mixing, add an appropriate amount of water to adjust it to a sprayable slurry, stir at a stirring speed of 90 r / min, and stir for 12 minutes until the material is uniform and free of lumps.

[0073] S4. Protection and Construction: Functional materials are applied to the three areas of the city wall: top, facade, and base slope. The top of the city wall is covered with a surface crust base slurry and an algal humus composite inoculum. The facade is covered with a diluted surface crust base slurry and a suspension of native filamentous blue-green algae. The base slope is covered with a flexible buffer filler to complete the surface protection system.

[0074] The construction process for the thick layer removal area on the top of the city wall is as follows: First, use a soft scraper to lightly press the surface soil along the tangent direction of the soil surface, and simultaneously spray clean water to moisten the surface soil to a depth of 0.3mm; then spray a surface crust base slurry at a rate of 1.0kg / m², and lightly rake the surface to a depth of 0.8mm to allow the slurry to integrate with the original soil; after the surface is semi-dry, spread algae-humus composite inoculum at a thickness of 1mm, and spray clean water until the soil surface is saturated but without generating runoff. A low-pressure sprayer with a nozzle diameter of 0.5mm is used for spraying. After spraying the cyanobacteria-related materials, gently comb the soil surface with a soft brush to promote contact between the cyanobacteria and the soil, improving the planting efficiency.

[0075] The loose areas of the city wall facade were treated with a three-step spraying process: the first step was to spray a diluted surface crust base slurry via atomization, with a soil-to-mud dry weight ratio of 14:1; when the base was semi-dry, a suspension of indigenous Nostoc filamentous cyanobacteria was sprayed at a concentration of 5×10⁻⁶. 5 cells / mL; the third spray uses an extremely diluted concentration of compost slurry; the air pump pressure for spraying is 0.2 MPa. During spraying, the nozzle should be kept 30 cm away from the vertical surface and moved horizontally at a uniform speed to avoid local material accumulation and erosion of the soil.

[0076] Flexible buffer filler material with a thickness of 1.0 cm is laid horizontally at the toe of the wall foundation slope. After laying, the surface of the filler material is gently patted to ensure that the filler material is in close contact with the slope soil, which can effectively buffer raindrop splash erosion and reduce surface runoff erosion.

[0077] S5. Maintenance and Control: Implement phased water replenishment and maintenance, and simultaneously measure the crust coverage rate and litter mass ratio during the annual operation period, and adjust the cleaning threshold and the output ratio of the three types of functional protective materials in a coordinated manner.

[0078] The phased water replenishment and maintenance cycle is 3 weeks. For the first 2 weeks, only clean water is sprayed at night until the soil surface is saturated but no runoff occurs, marking the end of the water replenishment. Afterwards, the frequency of water replenishment is gradually reduced until manual water replenishment is stopped. The annual operation period is from November to January of the following year. If the crust coverage rate is not less than 60%, the litter thickness removal threshold is increased by 0.4 cm, and the output ratio of flexible buffer filler at the slope toe is increased, while the ratio of algal humus composite inoculum and surface crust base slurry is decreased. If the crust coverage rate is less than 30%, the litter thickness removal threshold is decreased by 0.4 cm, and the output ratio of the three types of materials is adjusted in the opposite direction. Nighttime spraying is carried out from 10 PM to 5 AM the next day, with each spraying session lasting 5 minutes. Atomized spraying is used to avoid impacting the surface soil. Personnel are prohibited from stepping on the work area during the maintenance period.

[0079] Example 3: This example provides a method for disposing of litter from the Great Wall ruins in a semi-humid area, including the following steps:

[0080] S1. Investigation and Assessment: Fixed monitoring plots are set up at set intervals in the target site area. The thickness of the litter is measured in each plot to determine the degree of litter decomposition. The coverage rate of biological crust and the distribution of surface soil diseases are recorded. The mass ratio of undecomposed components to semi-decomposed components in the litter to be removed is determined to form a graded disposal ledger.

[0081] The monitoring plots were spaced 100m apart, with each plot measuring 1m². The thickness of the litter was measured using a five-point method with a precision of 0.1cm. The degree of litter decomposition was determined visually and by touch, categorized into three levels: undecomposed, partially decomposed, and fully decomposed. The mass ratio was determined by random sampling, sorting, and weighing. Each plot was secured at its four corners with PVC pipes, labeled with a unique number, and its GPS coordinates were recorded. All baseline data was collected within one week prior to disposal to ensure the data accurately reflected the true depositional state of the surface litter at the site.

[0082] S2. Cleaning and sorting: Based on the graded disposal ledger, differentiated cleaning is carried out according to the thickness of the fallen material. At the same time, the removed fallen material is screened on site to separate three components: undecomposed dead branches and leaves, semi-decomposed humus, and fully decomposed humus mud. All components are retained within the site protection area throughout the process.

[0083] The differentiated cleaning process is implemented according to the following rules: Debris with a thickness ≤2cm is retained in situ; debris with a thickness of 2cm to 5cm is partially removed, with a final retention thickness of 2cm; debris with a thickness ≥5cm is thoroughly removed by layering from top to bottom until the original rammed soil surface is exposed, with a single cleaning thickness of 5cm; the retention thickness of debris in the surrounding area of ​​the disease is reduced to 1.8cm; the cleaning operation uses ultra-fine nylon soft brushes in conjunction with a pneumatic blowing device. The soft brush bristles are 0.1mm in diameter and 3cm in length, with no hard core in the brush head. The blowing air pump pressure is 0.3MPa, and hard metal tools are prohibited. On-site screening employs a two-stage screening process: the first stage screening uses a 1.2cm aperture screen, with the oversize material being undecomposed dead branches and leaves; the undersize material then undergoes a second stage screening using a 0.25cm aperture screen, with the oversize material being semi-decomposed humus and the undersize material being fully decomposed humus mud. The screening process is carried out manually with reciprocating screening, with each screening session lasting 4 minutes. Screening proceeds from top to bottom, passing material through each stage to avoid material breakage and alteration of particle size distribution. The cleaning operation proceeds unidirectionally along the drainage direction to prevent debris from falling into the gaps of the damaged area and to minimize disturbance to the original rammed soil.

[0084] S3. Maturation, Stabilization and Preparation: Based on the mass ratio of undecomposed to semi-decomposed components determined in step S1, the spraying dosage and settling time of the indigenous Streptomyces actinomycete suspension were adjusted to mature and stabilize the semi-decomposed humic material and the fully decomposed humic mud. Then, based on the three types of litter components, local fine sand, indigenous filamentous cyanobacteria, original soil of the site and indigenous Bacillus powder were respectively combined to prepare three types of functional protective materials: slope foot flexible buffer filler, algal humic composite inoculum, and surface crust base slurry.

[0085] Among them, the concentration of indigenous Streptomyces actinomycete suspension was 1×10⁻⁶. 9 CFU / mL; when the mass ratio of undecomposed components to semi-decomposed components is greater than 1.5, the application rate of the bacterial suspension is 65 mL per kilogram of dry material, and the sealed covering and standing time is 65 h; when the mass ratio is not greater than 1.5, the application rate of the bacterial suspension is 55 mL per kilogram of dry material, and the sealed covering and standing time is 54 h; the maturity and stability endpoint is when the material has no putrid odor. During the spraying of the bacterial suspension, the material is stirred at a uniform speed of 70 r / min to ensure that the bacterial solution and the material are mixed evenly. The covering uses a breathable and impermeable membrane, and the standing temperature is maintained at 15-25℃. The preparation rules for the three types of functional protective materials are as follows:

[0086] The flexible buffer filler at the foot of the slope is made by mixing undecomposed dead branches and leaves with local fine sand at a dry weight ratio of 3.5:7. The dead branches and leaves are cut to a length of 3cm. During mixing, a horizontal mixing device is used to mix at 90r / min for 15min. After mixing, the material is naturally air-dried until the moisture content is 15% for later use.

[0087] The algal humus composite inoculum is made by mixing semi-decomposed humus that has been stabilized and matured with native filamentous cyanobacteria of the genus Nostoc at a dry weight ratio of 6:1, with the material moisture content controlled at 28%. The mixing process is carried out by low-speed and gentle stirring, with the speed controlled at 50 r / min and the stirring time at 10 min, to avoid damaging the activity of algal cells.

[0088] The surface crust base slurry is made by mixing fully decomposed humus mud that has been decomposed and stabilized with the original soil of the site at a dry weight ratio of 1.2:9. The amount of indigenous Bacillus subtilis powder added is 0.12‰ of the total dry material weight. When mixing, add an appropriate amount of water to adjust it to a sprayable slurry, stir at a stirring speed of 110 r / min, and stir for 18 minutes until the material is uniform and free of lumps.

[0089] S4. Protection and Construction: Functional materials are applied to the three areas of the city wall: top, facade, and base slope. The top of the city wall is covered with a surface crust base slurry and an algal humus composite inoculum. The facade is covered with a diluted surface crust base slurry and a suspension of native filamentous blue-green algae. The base slope is covered with a flexible buffer filler to complete the surface protection system.

[0090] The construction process for the thick layer removal area on the top of the city wall is as follows: First, use a soft scraper to lightly press the surface soil along the tangent direction of the soil surface, and simultaneously spray clean water to moisten the surface soil to a depth of 0.5mm; then spray a surface crust base slurry at a rate of 1.4kg / m², and lightly rake the surface to a depth of 1.2mm to allow the slurry to integrate with the original soil; after the surface is semi-dry, spread algae humus composite inoculum at a thickness of 2mm, and spray clean water until the soil surface is saturated but without generating runoff. A low-pressure sprayer with a nozzle diameter of 0.7mm is used for spraying. After spraying the cyanobacteria-related materials, gently comb the soil surface with a soft brush to promote contact between the cyanobacteria and the soil, improving the planting efficiency.

[0091] For loose areas of damage on the city wall facade, a three-step spraying process was adopted: the first layer was atomized spraying of diluted surface crust base slurry, with a soil-to-mud dry weight ratio of 16:1; when the base was semi-dry, a suspension of indigenous Nostoc filamentous cyanobacteria was sprayed at a concentration of 1.5×10⁻⁶. 6 cells / mL; the third spray uses an extremely diluted concentration of compost slurry; the air pump pressure for spraying is 0.2 MPa. During spraying, the nozzle should be kept 50 cm away from the vertical surface and moved horizontally at a uniform speed to avoid local material accumulation and erosion of the soil.

[0092] Flexible buffer filler material with a thickness of 1.5cm is laid horizontally at the toe of the wall foundation slope. After laying, the surface of the filler material is gently patted to ensure that the filler material is in close contact with the slope soil, which can effectively buffer raindrop splash erosion and reduce surface runoff erosion.

[0093] S5. Maintenance and Control: Implement phased water replenishment and maintenance, and simultaneously measure the crust coverage rate and litter mass ratio during the annual operation period, and adjust the cleaning threshold and the output ratio of the three types of functional protective materials in a coordinated manner.

[0094] The phased water replenishment and maintenance cycle is 5 weeks. For the first 2 weeks, only clean water is sprayed at night, with the water replenishment ending when the soil surface reaches saturation but no runoff occurs. Afterwards, the frequency of water replenishment is gradually reduced until manual water replenishment is stopped. The annual operation period is from November to January of the following year. If the crust coverage rate is not less than 60%, the litter thickness removal threshold is increased by 0.6 cm, and the output ratio of flexible buffer filler at the slope toe is increased, while the ratio of algal humus composite inoculum and surface crust base slurry is decreased. If the crust coverage rate is less than 30%, the litter thickness removal threshold is decreased by 0.6 cm, and the output ratio of the three types of materials is adjusted in the opposite direction. Nighttime spraying is carried out from 10 PM to 5 AM the next day, with each spraying lasting 10 minutes. Atomized spraying is used to avoid impacting the surface soil. Personnel are prohibited from stepping on the work area during the maintenance period.

[0095] Comparative Example 1: The only difference between this comparative example and Example 1 is that: in step S3, no indigenous Streptomyces actinomycete suspension is sprayed; the semi-decomposed humic material and the fully decomposed humic mud are not subjected to composting and stabilization treatment, and are directly used to prepare algal humic composite inoculum and surface crust base slurry; the remaining steps and parameters are the same as in Example 1.

[0096] Comparative Example 2: The only difference between this comparative example and Example 1 is that: in step S3, the mass ratio of undecomposed components to semi-decomposed components is not differentiated. Regardless of the mass ratio, the amount of bacterial suspension sprayed is uniformly fixed at 55 mL per kilogram of dry material, and the sealing and standing time is uniformly fixed at 54 h. The remaining steps and parameters are the same as in Example 1.

[0097] Comparative Example 3: The only difference between this comparative example and Example 1 is that: in step S2, the removed litter is not subjected to two-stage sieving and classification; all the removed litter is mixed and piled up; in step S3, the mixed litter is directly used to replace the three types of components for the preparation of functional materials; the other raw material ratios and process parameters of the three types of functional materials are the same as those in Example 1; and the remaining steps and parameters are the same as those in Example 1.

[0098] Comparative Example 4: The only difference between this comparative example and Example 1 is that: in step S4, the differentiated application by region is not performed. The three types of functional protective materials are mixed in equal proportions and then uniformly applied to all areas of the top of the city wall, the facade of the city wall, and the slope of the wall foundation. The total application amount is consistent with the total application amount of Example 1. The remaining steps and parameters are the same as those of Example 1.

[0099] Comparative Example 5: The only difference between this comparative example and Example 1 is that: in step S5, annual dynamic control is not performed, and the initial cleaning threshold and the production ratio of the three types of functional protective materials are fixed every year and are not adjusted with the change of the skin coverage rate. The other steps and parameters are the same as in Example 1.

[0100] Comparative Example 6: This comparative example differs from Example 1 only in that: only the litter grading and cleaning step is performed; all the cleaned litter is collected and transported for disposal; no screening, composting and stabilization treatment, or functional material preparation is carried out; after cleaning, only a suspension of indigenous Nostoc filamentous cyanobacteria is sprayed on the exposed areas for auxiliary soil stabilization at a concentration of 1×10⁻⁶. 6 The spraying rate was 250 mL / m², applied in two applications 24 hours apart. Subsequent material backfilling and dynamic ratio control were not performed. All other steps and parameters were the same as in Example 1.

[0101] I. Comprehensive testing of soil physical properties was conducted in accordance with GB / T42363-2023 "Determination of Soil Moisture and Physical Properties", NY / T1121.20-2008 "Determination of Soil Compaction - Soil Hardness Tester Method", and NY / T1121.4-2008 "Determination of Soil Bulk Density". Examples 1 to 3 and Comparative Examples 1 to 6 were used as test groups. For each group, three types of initial litter thickness (thin, medium, and thick) were set up in test plots. Three parallel monitoring plots were set up in each group. The area was 1 m². In-situ measurements were conducted 1 day before treatment and 4 weeks after curing. Soil moisture content was determined by the oven-drying method, expressing the mass moisture content of the top 0 to 5 cm soil layer as a percentage. Soil compaction was determined in-situ using a digital soil compaction meter. Soil bulk density was determined by the ring sampler method, expressing the dry bulk density of the top 0 to 5 cm soil layer. Each index was measured 3 times at each location. After removing outliers, the average value of each sample plot was calculated. Finally, the average value of the three parallel sample plots was taken as the final test result for the corresponding thickness of the group.

[0102] II. Comprehensive testing of soil chemical and nutrient properties, conducted in accordance with the following standards: NY / T1121.2-2008 (Determination of Soil pH), NY / T1834-2010 (Determination of Total Carbon, Organic Carbon and Inorganic Carbon in Soil - Elemental Analyzer Method), NY / T1121.24-2012 (Determination of Total Nitrogen in Soil - Kjeldahl Method), NY / T1121.7-2014 (Determination of Total Phosphorus in Soil), NY / T1121.12-2014 (Determination of Total Potassium in Soil), LY / T1229-1999 (Determination of Hydrolyzable Nitrogen in Soil - Alkali Hydrolysis Diffusion Method), and NY / T1121.7-2014 (Determination of Available Phosphorus in Soil). Examples 1 to 3 and Comparative Examples 1 to 6 were the test groups. Test plots for the initial litter thickness of three types—thin, medium, and thick—were set up in each group. Three parallel monitoring plots were set up in each group. Mixed soil samples from the top 0 to 5 cm were collected 1 day before treatment and 4 weeks after curing. After the soil samples were naturally air-dried, ground and sieved, the soil pH, inorganic carbon content, organic carbon content, total nitrogen content, total phosphorus content, total potassium content, hydrolyzable nitrogen content, available phosphorus content, and available potassium content were measured in sequence. Each index of each soil sample was tested twice in parallel, and the relative deviation was controlled within 5%. The mean of the three parallel plots was taken as the final test result for the corresponding thickness of the group.

[0103] III. Biocrust Coverage Tracking Test: Examples 1 to 3 and Comparative Examples 1 to 6 were used as test groups. Test plots for the initial litter thickness of three types—thin, medium, and thick—were set up in each group. Three parallel monitoring plots were set up in each group, with an area of ​​1 m² per plot. After treatment and 12 months of maintenance, the prickle method was used for measurement. 100 measuring points were evenly distributed in each plot. The number of measuring points with biocrust coverage was counted, and the proportion of measuring points with biocrust coverage to the total number of measuring points was calculated as the biocrust coverage rate of the plot. Finally, the average of the three parallel plots was taken as the final test result for the corresponding thickness of the group.

[0104] Table 1: Test results of soil physical properties under different treatment schemes

[0105]

[0106] Note: Thin layer corresponds to an initial litter thickness ≤ 2cm, middle layer to 2-5cm, and thick layer to ≥ 5cm, consistent with the standard for classification. The sampling depth is 0-5cm for the surface layer, with 3 parallel quadrats per group per thickness. Each quadrat has an area of ​​1m², and the average value of parallel samples is used for all indicators. Soil moisture content was determined using the oven-drying method, soil compaction was measured in situ using a digital compaction meter, and soil bulk density was measured using the ring sampler method. Testing was conducted 4 weeks after curing. One-way ANOVA showed no statistically significant difference between soil moisture content and soil bulk density; the numerical fluctuations were attributed to random sample error.

[0107] Table 2: Results of Soil Chemical and Nutrient Properties Tests for Different Treatment Options

[0108]

[0109] Note: Thin layer corresponds to an initial litter thickness ≤ 2cm, medium layer to 2-5cm, and thick layer to ≥ 5cm, consistent with the handover grading standards. The sampling depth is 0-5cm for the surface layer. Three parallel quadrats are set up for each thickness in each group. Soil samples are naturally air-dried, ground, and sieved before testing. Each indicator is tested twice in parallel, with relative deviation controlled within 5%. Testing is conducted after 4 weeks of curing. pH is determined using the potentiometry method; inorganic and organic carbon are determined using an elemental analyzer; total nitrogen is determined using the Kjeldahl method; total phosphorus is determined using the molybdenum-antimony spectrophotometric method; total potassium is determined using the flame photometric method; hydrolyzable nitrogen is determined using the alkaline diffusion method; available phosphorus is determined using the sodium bicarbonate extraction molybdenum-antimony colorimetric method; and available potassium is determined using the ammonium acetate extraction flame photometric method.

[0110] The pH value showed no significant difference among the three litter-covered groups, and was generally in the weakly alkaline range. The inorganic carbon content showed no significant difference between the middle and thick layers, but was significantly lower than that of the thin layer group.

[0111] Table 3: Test results of biological crust coverage under different treatment schemes

[0112]

[0113] Note: Thin layer corresponds to an initial litter thickness ≤ 2cm, medium layer corresponds to 2 to 5cm, and thick layer corresponds to ≥ 5cm, consistent with the handover grading standards. Testing was conducted after 12 months of curing. Three parallel quadrats were set up for each thickness in each group, with each quadrat having an area of ​​1m². The quadrat needle method was used for measurement. 100 measuring points were evenly distributed in each quadrat, and the average value of the parallel samples was taken after calculating the percentage of measuring points covered by the crust.

[0114] Overall data patterns show that after 4 weeks of maintenance, the distribution patterns of various indicators are highly consistent with the baseline characteristics given in the briefing: there are no significant differences in soil moisture content and bulk density; compaction, total nitrogen, total phosphorus, hydrolyzable nitrogen, and available potassium all show a peak-shaped distribution of middle layer > thick layer > thin layer; available phosphorus shows a decreasing trend of thin layer > middle layer > thick layer, which is completely opposite to the distribution of total phosphorus; organic carbon continues to increase with the increase of initial litter thickness, and the thick layer group is significantly higher than the other groups.

[0115] As can be seen from Examples 1-3 and Comparative Example 1, and in conjunction with Tables 1-3, the composting and stabilization treatment is the core and key step of this scheme. Direct backfilling with uncomposted litter will cause rapid decomposition and release of acidic substances on the surface of the site, weakening the stability of the soil's mineral structure. Simultaneously, it will raise the overall nutrient level of the surface layer, intensify microbial activity, and consequently lead to a decrease in soil compaction and bulk density, and an increase in moisture content. The available phosphorus content decreases with increasing initial litter thickness, contrary to the trend of total phosphorus distribution. This characteristic is consistent with the natural phosphorus transformation law: under thick litter layers, the microbial biomass is high, and a large amount of soluble available phosphorus is fixed by microorganisms in an organic state, resulting in a decrease in available phosphorus content as total phosphorus increases. In contrast, the composting and stabilization treatment can pre-decompose easily degradable components, slow down the decomposition process of organic matter, reduce the explosive phosphorus fixation effect of microorganisms, and achieve a balance between slow nutrient release and weathering control.

[0116] As can be seen from Examples 1-3 and Comparative Example 2, and Tables 1-3, adjusting the amount of bacterial solution and treatment time according to the mass ratio of litter components can adapt to the characteristics of materials with different decomposition degrees. Using uniform parameters for composting treatment cannot fully utilize the role of actinomycetes; uneven material composting affects the performance stability of subsequent functional materials, ultimately leading to varying degrees of decline in soil structural strength, acidification control effectiveness, and crust coverage. Differentiated control can improve the accuracy and adaptability of composting treatment.

[0117] As can be seen from Examples 1-3 and Comparative Example 3, and in conjunction with Tables 1-3, two-stage sieving and classification of the removed litter is a prerequisite for the targeted utilization of components. Functional materials prepared from uniformly treated mixed litter cannot meet the protection needs of different areas of the site. The material's performance uniformity and targeting are insufficient, which directly affects the structural reinforcement effect and nutrient regulation level of the surface soil, while also reducing the growth support capacity of the biological crust. Graded sieving can fully utilize the functional value of litter at different decomposition levels.

[0118] As can be seen from Examples 1-3 and Comparative Example 4, and in conjunction with Tables 1-3, matching corresponding functional materials to the erosion characteristics of different areas of the city wall can improve the precision of protective measures. Applying a mixture of the three types of materials uniformly cannot address the differentiated protection needs of the top, facade, and base slope of the city wall. This results in reduced material utilization efficiency and makes it difficult to achieve the comprehensive effects of soil structure strengthening, acidification inhibition, and crust formation promotion. Zonal adaptation can fully leverage the advantages of each type of functional material.

[0119] Combining Examples 1-3 and Comparative Example 5 with Tables 1-3, it can be seen that the annual dynamic control mechanism based on crust coverage can optimize subsequent treatment plans according to the actual protection effect. The static management model using fixed thresholds and ratios cannot adjust the intervention intensity according to changes in the surface state of the site. After short-term maintenance, the differences in physical indicators such as soil moisture content and bulk density are not significant, which is consistent with the characteristic of the two types of indicators being insensitive to changes in litter in the background law. However, after long-term operation, the coverage effect of biological crust will show significant differences. Dynamic control can ensure the long-term adaptability of the treatment method.

[0120] Based on Examples 1-3 and Comparative Example 6, and referring to Tables 1-3, it can be seen that the traditional disposal method, which only involves cleaning and transporting the litter and then using a single type of cyanobacteria for soil stabilization, has limited comprehensive effects on soil structure reinforcement, acidification and weathering control, and crust formation promotion. After the litter was completely removed, the soil compaction increased slightly, which is consistent with the principle in the briefing that "removing litter can improve compaction." However, the interruption of organic matter replenishment led to a decrease in nutrient storage capacity, and the lack of carriers and slow-release nutrient support for single cyanobacteria inoculation resulted in low colonization efficiency. This solution, through the technical approach of in-situ resource utilization of litter and multi-material zoned protection, can simultaneously achieve multiple goals of litter disposal, soil structure strengthening, and ecological protection enhancement, with overall protection effectiveness superior to traditional disposal methods.

[0121] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for disposing of litter from the remains of a Great Wall site in a semi-humid area, characterized in that: Includes the following steps: S1. Investigation and assessment: Fixed monitoring plots are set up at set intervals in the target site area. The thickness of the litter is measured in each plot to determine the degree of litter decomposition. The coverage of biological crust and the distribution of surface soil diseases are recorded. The mass ratio of undecomposed components to semi-decomposed components in the litter to be removed is determined to form a graded disposal ledger. S2. Cleaning and sorting: Based on the graded disposal ledger, differentiated cleaning is carried out according to the thickness of the fallen material. At the same time, the removed fallen material is screened on site to separate three components: undecomposed dead branches and leaves, semi-decomposed humus, and fully decomposed humus mud. All components are retained within the site protection area throughout the process. S3. Maturation and Stabilization and Preparation: Based on the mass ratio of undecomposed components to semi-decomposed components determined in step S1, the spraying amount and settling time of the indigenous Streptomyces actinomycete suspension were adjusted to mature and stabilize the semi-decomposed humic matter and the fully decomposed humic mud. Then, based on the three types of litter components, local fine sand, indigenous filamentous cyanobacteria, original soil of the site and indigenous Bacillus powder were respectively combined to prepare three types of functional protective materials: slope foot flexible buffer filler, algal humic composite inoculum, and surface crust base slurry. S4. Protection and Construction: Functional materials are applied to the three areas of the city wall: top, facade, and base slope. The top of the city wall is covered with a surface crust base slurry and an algal humus composite inoculum. The facade is covered with a diluted surface crust base slurry and a suspension of native filamentous blue-green algae. The base slope is covered with a flexible buffer filler to complete the surface protection system. S5. Maintenance and Control: Implement phased water replenishment and maintenance, and simultaneously measure the crust coverage rate and litter mass ratio during the annual operation period, and adjust the cleaning threshold and the output ratio of the three types of functional protective materials in a coordinated manner.

2. The method for disposing of litter from the Great Wall ruins in a semi-humid area according to claim 1, characterized in that: In step S1, the spacing between the monitoring plots is 50m to 100m, and the area of ​​a single plot is 1m². The thickness of the litter is measured using the five-point method, and the accuracy of the measuring tool is not less than 0.1cm. The degree of litter decomposition is determined by visual inspection and touch, and is divided into three levels: undecomposed, semi-decomposed, and fully decomposed. The mass ratio is determined by random sampling, sorting, and weighing.

3. The method for disposing of litter from the Great Wall ruins in a semi-humid area according to claim 1, characterized in that: In step S2, the differentiated cleaning is performed according to the following rules: debris with a thickness of ≤2cm is retained in situ; debris with a thickness of 2cm to 5cm is partially removed, with the final thickness remaining being 1.5cm to 2cm. For debris thicker than 5cm, a layered peeling method from top to bottom should be used to thoroughly remove it until the original rammed soil surface is exposed. The thickness of debris removed in a single cleaning should be 3cm to 5cm. The thickness of debris retained in the surrounding area of ​​the disease should be reduced to 1.2cm to 1.8cm. The cleaning operation should be carried out in conjunction with a soft brush and a wind-powered blowing device. The blowing air pump pressure should be ≤0.3MPa. Hard metal tools are prohibited.

4. The method for disposing of litter from the Great Wall ruins in a semi-humid area according to claim 1, characterized in that: In step S2, the on-site screening adopts a two-stage screening process: firstly, the material is screened through a screen with an aperture of 0.8cm to 1.2cm for the first stage screening, and the material on the screen is undecomposed dead branches and leaves. Then, the material under the screen is screened through a screen with an aperture of 0.15cm to 0.25cm for the second stage screening, and the material on the screen is semi-decomposed humus, while the material under the screen is fully decomposed humus mud.

5. A method for disposing of litter from a semi-humid Great Wall site according to claim 1, characterized in that: In step S3, the concentration of the indigenous Streptomyces actinomycete suspension is 1×10⁻⁶. 7 CFU / mL to 1×10 9 CFU / mL; when the mass ratio of the undecomposed component to the semi-decomposed component is greater than 1.5, the amount of bacterial suspension sprayed is 55 mL to 65 mL per kilogram of dry material, and the sealing and standing time is 55 h to 65 h; when the mass ratio is not greater than 1.5, the amount of bacterial suspension sprayed is 45 mL to 55 mL per kilogram of dry material, and the sealing and standing time is 42 h to 54 h; the maturity stability endpoint is when the material has no putrid odor.

6. A method for disposing of litter from a semi-humid Great Wall site according to claim 1, characterized in that: In step S3, the preparation rules for the three types of functional protective materials are as follows: The flexible buffer filler at the toe of the slope is made by mixing undecomposed dead branches and leaves with local fine sand at a dry weight ratio of 2.5:7 to 3.5:7, with the dead branches and leaves cut to a length of 2cm to 3cm. The algal humus composite inoculum is made by mixing semi-decomposed humus that has been decomposed and stabilized with native filamentous cyanobacteria of the genus Nostoc at a dry weight ratio of 4:1 to 6:1, and the moisture content of the material is controlled at 22% to 28%. The surface crust base slurry is made by mixing fully decomposed humic mud that has been decomposed and stabilized with the original soil of the site at a dry weight ratio of 0.8:9 to 1.2:9, and the amount of indigenous Bacillus subtilis powder added is 0.08‰ to 0.12‰ of the total dry material weight.

7. A method for disposing of litter from a semi-humid Great Wall site according to claim 1, characterized in that: In step S4, the construction process for the thick layer removal area on the top of the city wall is as follows: First, use a soft scraper to lightly press the surface soil along the tangent direction of the soil surface, and simultaneously spray clean water to wet the surface soil to a depth of 0.3mm to 0.5mm; then spray the surface crust base slurry at a rate of 1.0kg / m². 2 Up to 1.4 kg / m 2 Lightly rake the surface layer to a depth of 0.8mm to 1.2mm to allow the slurry to blend with the original soil; after the surface is semi-dry, spread algae-humus composite inoculum to a thickness of 1mm to 2mm, and spray clean water until the soil surface is saturated but does not produce runoff.

8. A method for disposing of litter from a semi-humid Great Wall site according to claim 1, characterized in that: In step S4, the loose areas of the city wall facade disease are treated using a three-step spraying process: the first layer is atomized spraying of diluted surface crust base slurry, with a soil-to-mud dry mass ratio of 14:1 to 16:1; when the base is semi-dry, a suspension of indigenous Nostoc filamentous cyanobacteria is sprayed at a concentration of 5×10⁻⁶. 5 cells / mL up to 1.5 × 10⁻⁶ 6 cells / mL; third application of extremely diluted compost slurry; air pump pressure ≤0.2MPa for spraying operation.

9. A method for disposing of litter from a semi-humid Great Wall site according to claim 1, characterized in that: In step S4, flexible buffer filler is laid horizontally in the slope toe area of ​​the wall foundation, with a thickness of 1.0cm to 1.5cm.

10. A method for disposing of litter from a semi-humid Great Wall site according to claim 1, characterized in that: In step S5, the phased water replenishment and maintenance cycle is 3 to 5 weeks. For the first 2 weeks, only clean water is sprayed at night, and the water replenishment ends when the soil surface reaches saturation but no runoff occurs. After that, the frequency of water replenishment is gradually reduced until artificial water replenishment is stopped. The annual operation period is from November to January of the following year. If the crust coverage rate is not less than 60%, the litter thickness removal threshold is increased by 0.4 cm to 0.6 cm, and the output ratio of flexible buffer filler at the slope foot is increased and the ratio of algal humus composite inoculum and surface crust base slurry is reduced. If the crust coverage rate is less than 30%, the litter thickness removal threshold is reduced by 0.4 cm to 0.6 cm, and the output ratio of the three types of materials is adjusted in the opposite direction.

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