Simulated earthen ruin rammed earth test wall manufacturing method based on original diseases

Abstract

The invention discloses a method for manufacturing a simulated earthen ruins rammed earth test wall based on original diseases, and relates to the field of earthen ruins protection and restoration. The method comprises the following steps: step 1, determining earthen archaeological site diseases to be researched and preparing materials; 2, mold assembling and disease marking are carried out; 3, layered ramming is conducted; step 4, crack disease processing; step 5, performing undercutting disease processing; 6, weathering disease processing; step 7, processing rain erosion diseases; and step 8, northwest environment simulation. The earthen archaeological site rammed earth wall is manufactured by integrating multiple disease collaborative simulation technologies of fissure, undermining, weathering and rain erosion, meanwhile, adaptability design of a strong wind erosion area, a strong sunshine area and a strong salinization area is made for northwest arid areas, and the method has the core advantages of disease reproduction authenticity, standardized grading, environment adaptability and the like; a scientific and reasonable technical means is provided for earthen archaeological site protection engineering, and a reliable test piece is provided for research and development of a protection technology.

Description

Technical Field

[0001] This invention belongs to the field of earthen site protection and restoration, specifically a method for constructing a simulated rammed earth test wall based on original defects in earthen sites. Background Technology

[0002] Earthen sites are an important carrier of Chinese civilization. Due to environmental factors such as strong wind erosion, high sunlight, and salinization, earthen sites in the arid Northwest region generally suffer from diseases such as cracks, erosion, weathering, and rain erosion. To carry out conservation technology research, it is necessary to create test walls with real diseases.

[0003] Current methods for constructing rammed earth test walls for earthen archaeological sites suffer from systemic defects, severely hindering the scientific rigor and engineering applicability of conservation research. First, the simulation of damage lacks realism: while the widely adopted retro-style rammed earth technique can reproduce surface texture and color, it only scratches the surface, failing to reconstruct the key internal structures of the earthen archaeological site or preserve the cracks of the actual site. This results in significant discrepancies between the constructed rammed earth test walls and the actual site, leading to a substantial disconnect between reinforcement experimental data and actual engineering results. Second, the coupling mechanism of multiple damages is lacking. Existing methods primarily target single damages, such as cracks or chemical corrosion, failing to reflect the interaction of multiple damages and ignoring the chain-like degradation mechanism of crack-saltification-wind erosion. Finally, environmental adaptability is poor; the methods are not tailored to the arid northwest region, and the simulated wind speed, sunlight, and salinity deviate significantly from actual conditions. Therefore, current technology lacks a method for constructing simulated rammed earth test walls for earthen archaeological sites based on original damage, making it difficult to achieve effective protection of earthen archaeological sites with reinforcing agents and hindering scientific policies for the preventative protection of these sites.

[0004] Therefore, based on the need to strengthen the protection of cultural relics and heritage and enhance the protection policies for the preservation and inheritance of historical and cultural heritage in urban and rural construction, there is an urgent need for a method to accurately reproduce multiple diseases and adapt to the arid Northwest region to create a simulated rammed earth test wall, providing reliable test specimens for the research and development of protection technologies and breaking through the constraints of existing technologies on the scientific decision-making for the preventive protection of earthen sites.

[0005] The information disclosed above in this background section is only for enhancing the understanding of the background section of this invention, and therefore may include prior art that is not known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a method for constructing a simulated rammed earth test wall based on original defects, which can accurately reproduce multiple defects and is suitable for simulated rammed earth test walls in the arid Northwest region. This provides reliable test specimens for the research and development of protection technologies and overcomes the constraints of existing technologies on the scientific decision-making for the preventive protection of earthen sites.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for constructing a rammed earth test wall for a simulated earthen archaeological site based on original defects, comprising the following steps:

[0008] Step 1: Identify the defects of the earthen site to be studied and prepare materials.

[0009] Prepare rammed earth materials, disease simulation materials, and mold equipment based on the earthen site to be studied;

[0010] Step 2: Mold assembly and defect marking

[0011] Assemble the wooden template, mark the layer lines on the inside of the template, mark the direction of the cracks and the division of the erosion area according to the current status of the disease of the soil site to be studied, pre-embed foam blocks at the bottom to simulate foundation erosion, and pre-embed thin wooden strips to simulate cracks in combination with the actual disease.

[0012] Step 3: Layered compaction

[0013] Layer by layer, 15cm thick, and spread soil into the wooden template. Each layer is tamped 6 times. Diluted glutinous rice juice is brushed between layers and the surface is leveled. The top layer is the weathering layer, which is spread with soil, lightly tamped 4 times, and then leveled.

[0014] Step 4: Processing of fissure defects

[0015] Extract the thin wood strips and create cracks based on the actual disease. To simulate crack expansion, use an awl to create branches at the ends. If it is a regular crack, use a cutting machine to create grooves.

[0016] Step 5: Treatment of erosion defects

[0017] Remove the bottom foam block, correct the edge position to "dog tooth shape", and combine it with the actual situation to form an eroded cavity;

[0018] Step 6: Processing of weathering defects

[0019] Based on the actual disease, the surface of the rammed earth wall was sandblasted to form a weathered layer. Then, a 5% Na2SO4 solution was sprayed and soaked for 24 hours and dried for 48 hours. This process was repeated three times to induce efflorescence on the surface of the rammed earth wall.

[0020] Step 7: Treatment of Rain Erosion Damage

[0021] A rotating rain shower head was installed on the top of the rammed earth test wall to simulate the erosion of heavy rain until a gully was formed at the bottom of the rammed earth wall.

[0022] Step 8: Northwest Environmental Simulation

[0023] (1) Strong wind erosion simulation: An axial flow fan is arranged on one side of the rammed earth test wall. Combined with the environment of the rammed earth wall to be studied, the maximum wind speed is continuously blown, and wind and sand are combined to create wind erosion pits.

[0024] (2) Strong sunlight simulation, in a xenon lamp aging chamber (1.2kW / m²) 2 Irradiate at 60℃ for 12 hours daily for 15 days to induce surface cracking.

[0025] (3) Strong salt accumulation simulation: 1.5% NaCl + Na2SO4 mixed salt was mixed in the soil at the bottom of the rammed earth wall. After 3 dry and wet cycles, a salt crystal layer with a thickness of 10 to 15 mm was formed at the base of the wall.

[0026] Preferably, the rammed earth material is the original soil surrounding the site to be studied, with a moisture content of 15% to 18%, and is mixed with 5% glutinous rice juice and 1% alum.

[0027] Preferably, the disease simulation material includes thin wood strips, foam blocks, and Na2SO4. The wood strips are 100mm long and are used to create through cracks; the foam blocks are 10×15×5cm in size and are used to create erosion cavities.

[0028] Preferably, the mold equipment includes a detachable wooden template, a sandblasting machine, and an artificial rain system; the wooden template has dimensions of 2×1.5×0.5m, and the inner side of the template is marked with layer lines and pre-set defect locations every 15-20cm; the sandblasting machine has a pressure of 0.3MPa; the artificial rain system has a rotatable nozzle.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. This invention incorporates a synergistic simulation technology for multiple diseases such as fissures, erosion, weathering, and rain erosion to construct rammed earth walls for earthen archaeological sites. It also develops adaptable designs for strong wind erosion, strong sunlight, and strong salinity areas in the arid Northwest region. It has core advantages such as realistic disease reproduction, standardized grading, and environmental adaptability, providing a scientific and reasonable technical means for the protection of earthen archaeological sites and reliable test specimens for the research and development of protection technologies. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0032] Figure 1 This is a schematic diagram of the manufacturing method of the present invention;

[0033] Figure 2 A comparison of the colors of the walls before and after reinforcement in a field simulation experiment;

[0034] Figure 3 Construction drawings before and after the aging process;

[0035] Figure 4 This is a diagram of a simulation experiment involving ultraviolet irradiation.

[0036] Figure 5Stress and strain curves of undisturbed rammed earth soil sample Q-1-3;

[0037] Figure 6 Stress and strain curves of BS-10a reinforced rammed soil sample Q-2-2;

[0038] Figure 7 Stress and strain curves of BS-10b reinforced rammed earth sample Q-3-2;

[0039] Figure 8 A comparison diagram of stress and strain curves before and after rammed earth reinforcement;

[0040] Figure 9 Stress-strain curves of undisturbed soil sample Q-4-1 (for adobe bricks);

[0041] Figure 10 Stress-strain curves for BS-10a reinforced adobe sample Q-5-1;

[0042] Figure 11 Stress and strain curves for BS-10b reinforced adobe sample Q-6-2;

[0043] Figure 12 A comparison diagram of stress and strain curves before and after adobe reinforcement;

[0044] Figure 13 Stress and strain curves of undisturbed soil sample Q-8-1 from Sakazuki;

[0045] Figure 14 Stress and strain curves of soil sample Q-9-1 for BS-10a reinforced slope;

[0046] Figure 15 Stress and strain curves of soil sample Q-10-1 for BS-10b reinforced slope;

[0047] Figure 16 Comparison of stress and strain curves before and after reinforcement of the slope with earthen embankment;

[0048] Figure 17 A schematic diagram illustrating the failure mode of BS-10 after reinforcement – ​​spalling;

[0049] Figure 18 Schematic diagram of the failure mode after reinforcement of the slope with earthen soil - surface cracking;

[0050] Figure 19 The experimental temperature progression line (I);

[0051] Figure 20 This is the experimental temperature progression line (II). Detailed Implementation

[0052] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0053] Example 1:

[0054] A method for constructing a simulated rammed earth test wall for an ancient archaeological site based on original defects includes the following steps:

[0055] Step 1: Identify the defects of the earthen site to be studied and prepare materials.

[0056] Prepare rammed earth materials, disease simulation materials, and mold equipment based on the earthen site to be studied;

[0057] Specifically, the rammed earth material was the original soil surrounding the site to be studied, with a moisture content of 15% to 18%, mixed with 5% glutinous rice juice and 1% alum.

[0058] Specifically, the disease simulation materials include thin wood strips, foam blocks, and Na2SO4. The wood strips are 100mm long and are used to create through cracks; the foam blocks are 10×15×5cm in size and are used to create erosion cavities.

[0059] Specifically, the mold equipment includes a detachable wooden template, a sandblasting machine, and an artificial rain system; the wooden template is 2×1.5×0.5m in size, with layer lines and pre-set defect locations marked every 15-20cm on the inside of the template; the sandblasting machine has a pressure of 0.3MPa; and the artificial rain system has a rotatable nozzle.

[0060] Step 2: Mold assembly and defect marking

[0061] Assemble the wooden template, mark the layer lines on the inside of the template, mark the direction of the cracks and the division of the erosion area according to the current status of the disease of the soil site to be studied, pre-embed foam blocks at the bottom to simulate foundation erosion, and pre-embed thin wooden strips to simulate cracks in combination with the actual disease.

[0062] Step 3: Layered compaction

[0063] Layer by layer, 15cm thick, and spread soil into the wooden template. Each layer is tamped 6 times. Diluted glutinous rice juice is brushed between layers and the surface is leveled. The top layer is the weathering layer, which is spread with soil, lightly tamped 4 times, and then leveled.

[0064] Step 4: Processing of fissure defects

[0065] Extract the thin wood strips and create cracks based on the actual disease. To simulate crack expansion, use an awl to create branches at the ends. If it is a regular crack, use a cutting machine to create grooves.

[0066] Step 5: Treatment of erosion defects

[0067] Remove the bottom foam block, correct the edge position to "dog tooth shape", and combine it with the actual situation to form an eroded cavity;

[0068] Step 6: Processing of weathering defects

[0069] Based on the actual disease, the surface of the rammed earth wall was sandblasted to form a weathered layer. Then, a 5% Na2SO4 solution was sprayed and soaked for 24 hours and dried for 48 hours. This process was repeated three times to induce efflorescence on the surface of the rammed earth wall.

[0070] Step 7: Treatment of Rain Erosion Damage

[0071] A rotating rain shower head was installed on the top of the rammed earth test wall to simulate the erosion of heavy rain until a gully was formed at the bottom of the rammed earth wall.

[0072] Step 8: Northwest Environmental Simulation

[0073] (1) Strong wind erosion simulation: An axial flow fan is arranged on one side of the rammed earth test wall. Combined with the environment of the rammed earth wall to be studied, the maximum wind speed is continuously blown, and wind and sand are combined to create wind erosion pits.

[0074] (2) Strong sunlight simulation, in a xenon lamp aging chamber (1.2kW / m²) 2 Irradiate at 60℃ for 12 hours daily for 15 days to induce surface cracking.

[0075] (3) Strong salt accumulation simulation: 1.5% NaCl + Na2SO4 mixed salt was mixed in the soil at the bottom of the rammed earth wall. After 3 dry and wet cycles, a salt crystal layer with a thickness of 10 to 15 mm was formed at the base of the wall.

[0076] To further verify the effectiveness of the simulated earthen archaeological site rammed earth test wall produced by this invention, the following experiments were conducted and corresponding samples were prepared according to the method of this invention:

[0077] 1. Color observation and UV resistance test before and after reinforcement. A total of 6 cubic specimens (50mm × 50mm × 50mm) were prepared.

[0078] 2. Wetting test before and after reinforcement. A total of 27 cubic specimens with a diameter of 50 mm × 50 mm × 50 mm were prepared for the experiment.

[0079] 3. Compressive strength test before and after reinforcement. A total of 40 cylindrical specimens with a diameter of 39.1 mm × 80 mm were prepared for the experiment.

[0080] 4. Freeze-thaw test before and after reinforcement. A total of 30 cubic specimens (50mm × 50mm × 50mm) were prepared for the experiment.

[0081] Sample preparation and reinforcement were carried out on-site, which reduced the workload of soil transportation and minimized changes in soil properties caused by environmental changes during off-site transport. Samples were cut and ground manually, and all samples were original samples from the site.

[0082] Reinforcement Method: Except for the color observation experiment before and after reinforcement, which was a field simulation, all other samples used in this experiment were prepared on-site and then sprayed with a spray bottle. The spraying was done in five stages, with the interval between sprays determined by visual observation. The standard was that the soil sample was approximately 90% dry after each spray. After the five sprays, the soil sample was placed in a shaded area to air dry for 7 days, and then placed in the open-air environment of the site itself.

[0083] 1. Color observation before and after reinforcement, and UV resistance test.

[0084] This experiment employed three methods: on-site simulation, actual construction, and indoor testing. The on-site simulation involved applying the chemical reinforcing agent to the soil without any aging treatment, serving as the basis for evaluation. The actual construction experiment involved applying the chemical reinforcing agent to the soil after aging treatment, serving as the basis for evaluation. The wall colors before and after reinforcement in the on-site simulation experiment are shown in the image. Figure 2 As shown in the image, the soil turned yellow after the addition of the chemical stabilizing agent, but the color change remained within the same color family and the magnitude of the change was not significant. Over time, the color gradually approached the original color of the soil. After the actual construction was completed, the reinforced soil underwent an aging treatment. A comparison of the soil's color before and after is shown in the image. Figure 2 After two months of exposure to wind and rain, the reinforced and distressed wall surface retained its original color without any change. To more clearly demonstrate the color difference before and after reinforcement, color difference analysis was performed on the test blocks before and after reinforcement. Simultaneously, the test blocks were placed under the illumination of a 300W high-pressure mercury lamp, with the sample surface 2cm away from the light source (see...). Figure 3 The experiment involved 500 hours of irradiation. After the experiment, color difference analysis was performed. The results of the color difference analysis were expressed using the index corresponding to the internationally recognized CIE lab color gamut space. The testing instrument was a TC-PⅡG fully automatic colorimeter.

[0085] The color difference analysis results of rammed earth and adobe brick undisturbed soil samples before and after reinforcement are shown in Tables 1.1 to 1.4.

[0086] Table 1.1 Comparison Table of Color Difference Analysis for X-1 and X-2

[0087]

[0088] Table 1.2 Comparison Table of Color Difference Analysis for X-1 and X-3

[0089]

[0090] Table 1.3 Comparison Table of Color Difference Analysis for X-4 and X-5

[0091]

[0092] Table 1.4 Comparison Table of Color Difference Analysis for X-4 and X-6

[0093]

[0094] Color difference analysis of rammed earth and adobe undisturbed soil samples before and after ultraviolet irradiation (test results are shown in Tables 1.5 to 1.10).

[0095] Table 1.5X-1 Ultraviolet Irradiation Color Difference Comparison Table

[0096]

[0097] Table 1.6X-2 Ultraviolet Irradiation Color Difference Comparison Table

[0098]

[0099] Table 1.7 Comparison of color difference analysis before and after X-3 ultraviolet irradiation

[0100]

[0101] Table 1.8X-4 Ultraviolet Irradiation Color Difference Comparison Table

[0102]

[0103]

[0104] Table 1.9X-5 Ultraviolet Irradiation Color Difference Comparison Table

[0105]

[0106] Table 1.10X-6 Ultraviolet Irradiation Color Difference Comparison Table

[0107]

[0108] The data above shows that the soil color of the site underwent localized changes after reinforcement, with a total color difference between 6 and 11 compared to the unreinforced soil sample. After 500 hours of ultraviolet irradiation, the soil color also changed to some extent before and after reinforcement, with a color difference between 0 and 6, and only one value greater than 6. While the magnitude of the color difference can directly reflect the extent of color change to some extent, there are significant differences between different industries and different items. During the experiment, the uneven surface of the manually processed soil sample affected the varying ambient light levels during the test, thus influencing the results. The data reveals that the main influencing factor on the total color difference is ΔL* (the lightness value of the object's color), while ΔA* (information value indicating whether the object's color leans towards red or green) and ΔB* (information value indicating whether the object's color leans towards blue or yellow) are very small. Generally, a color difference ≤ 6 is imperceptible to the naked eye. Since the soil samples reinforced in this experiment were not subjected to any aging treatment before the experiment, the data and analysis above show that the soil samples reinforced with the BS-10 series reinforcement agent underwent some color change before the aging treatment, but the change was minor and can be considered as no color change at all. Under ultraviolet light, although the color changed slightly, it was not noticeable to the naked eye. Therefore, the experiment demonstrates that the BS-10 series reinforcement agent has strong UV resistance.

[0109] 2. Soil wetting test before and after reinforcement

[0110] The performance of soil samples from the Yulin Ming Great Wall earthen site was compared using different proportions of BS-10 reinforcing agent. The experimental results are shown in Table 2.1. The performance of soil samples from the Gaochang Ancient City Dafosi site was compared using two different formulations of 10% BS-10 reinforcing agent. The experimental results are shown in Table 2.2. Table 2.1 shows that the water resistance of the soil samples increases with increasing concentration. Table 2.2 shows that the soil's resistance to disintegration is increased to some extent after reinforcement with the BS-10 series, but the effect varies for different soil types. For the soil at the Gaochang Ancient City Dafosi site, although the water resistance improved after reinforcement, the increase was not significant. However, considering the climate conditions of Turpan, Xinjiang, where Gaochang Ancient City is located, this region is arid with little rainfall, averaging only a few millimeters per year. Therefore, under normal circumstances, rainwater cannot completely saturate the soil of the site. Experimental results show that the BS-10 series of reinforcing agents have a certain water resistance for earthen sites in arid Northwest China.

[0111] Table 2.1 Results of the Wetting Experiment of the Yulin Ming Great Wall Earthen Site

[0112]

[0113]

[0114] Table 2.2 Results of the Wetting Experiment of the Earthen Site of the Great Buddha Temple in the Ancient City of Gaochang

[0115]

[0116]

[0117] 3. Strength test before and after reinforcement

[0118] According to the "Standard for Geotechnical Testing Methods" (GB / T50123—1999), the instrument used is a YYW-2 strain-controlled unconfined compressive strength gauge. Before the test, the sample is placed on the base, and the handwheel is rotated to slowly raise the base. When the sample just contacts the pressure plate, the reading of the force gauge is adjusted to zero. The axial strain rate is 1%–3% per minute when the handwheel is rotated. When the axial strain is <3%, a reading is taken every 0.5% strain (or 0.4 mm); when the axial strain is ≥3%, a reading is taken every 1% strain. The unconfined compressive strength comparison table for rammed soil is shown in Table 3.1. The stress-strain curves for typical soil samples are shown in [Table 3]. Figures 5-7 The stress and strain comparison diagrams before and after reinforcement are shown below. Figure 8 Table 3.1 shows that the strength of the rammed earth samples reinforced by BS-10a and BS-10b increased in the short term, with increases of 1.395 times and 1.391 times, respectively. Table 3.2 shows the comparison table of unconfined compressive strength of adobe bricks. The stress-strain curves of typical soil samples are shown in the table. Figures 9-11 The stress and strain comparison diagrams before and after reinforcement are shown below. Figure 12 Table 3.2 shows that the strength of the adobe samples reinforced by BS-10a and BS-10b increased in the short term, with increases of 1.274 times and 1.602 times, respectively. Table 3.3 shows the comparison table of unconfined compressive strength of slab-built soils. The stress-strain curves of typical soil samples are shown in the table. Figures 13-15 The stress and strain comparison diagrams before and after reinforcement are shown below. Figure 16 Table 3.3 shows that the strength of the adobe samples reinforced by BS-10a and BS-10b increased in the short term, with increases of 1.314 times and 1.259 times, respectively. The anchor fill soil samples were prepared using BS-10c slurry and manually vibrated using steel molds as required by the geotechnical testing procedures. The strength one month after molding is shown in Table 3.4. The table shows that the soil samples directly mixed with BS-10c reinforcement showed a strength approximately 1.7 times higher than the strength of adobe and rammed earth undisturbed soil.

[0119] Table 3.1 Comparison of compressive strength before and after rammed earth reinforcement at the Gaochang Ancient City Dafosi Site

[0120]

[0121] Table 3.2 Comparison of compressive strength before and after reinforcement with adobe bricks at the Gaochang Ancient City Dafosi Site

[0122]

[0123]

[0124] Table 3.3 Comparison of compressive strength before and after earthwork reinforcement at the Gaochang Ancient City Dafosi Site

[0125]

[0126] Table 3.4 Compressive strength of soil samples from anchor bolt grouting at the Gaochang Ancient City Dafosi Site

[0127]

[0128] The data above shows that as the moisture content of the soil increases to a certain extent after the addition of the reinforcing agent, the change in moisture content has little effect on the compressive strength of the soil. For the same soil with similar moisture content, there is no obvious pattern of strength variation. During the experiment, it was found that the BS-10 series reinforcing agent did not exhibit a "crusting" phenomenon after reinforcing rammed earth and adobe bricks; almost all soil failures were characterized by sudden, unpredictable cracking (see...). Figure 17 The failure mode of reinforced earthen walls differs from that of adobe and rammed earth. Because a large amount of straw is added to the earthen walls, and the straw is not completely dry in a short period, the bonding effect between the straw prevents the earthen walls from collapsing. Therefore, failure usually occurs through cracking on all four sides (see...). Figure 18 ).

[0129] In summary, the BS-10 series reinforcing agent can appropriately improve the compressive strength of soil. After reinforcement, there is no "crust" phenomenon on the soil surface, and the reinforced soil surface has good connection strength with the internal soil.

[0130] 4. Freeze-thaw test of soil samples before and after reinforcement

[0131] This experiment used soil samples from the Gaochang Ancient City Dafosi Site as the sample, and based on the local monthly average temperature and annual maximum and minimum temperatures from 2018 to 2022 provided by the Turpan Meteorological Bureau, it simulated the monthly average temperature change process for 12 months of the year in a 12-hour cycle, keeping the test temperature fluctuating within the range of -20℃ to 50℃. One cycle of temperature change completed one freeze-thaw cycle. After each cycle, the soil sample damage morphology was visually observed and photographed to record the process. Temperature data for Gaochang Ancient City from 2018 to 2022 are shown in Tables 4.1 and 4.2. The experimental equipment used was the PT-2230 freeze-thaw cycle testing machine from the Shaanxi Provincial Academy of Building Research. Due to inherent limitations of the equipment, the influence of monthly average relative humidity was not considered in this experiment. Furthermore, to avoid the negative impact of rapid temperature changes on the soil sample during the simulation, each constant temperature period was set to 40 minutes, with 20 minutes of slow temperature increases and decreases used to regulate this rapid temperature change. The experimental temperature progression line (I) is shown below. Figure 19 .

[0132] Table 4.1 Average Temperature Data of Gaochang Ancient City from 2018 to 2022

[0133]

[0134]

[0135] Table 4.2 Monthly maximum and minimum temperature data of Gaochang Ancient City from 2018 to 2022

[0136]

[0137] After five freeze-thaw cycles, the test results are shown in Table 4.3. Table 4.3 shows that the soil samples remained largely unchanged during the freeze-thaw cycle. Although cracks appeared on the surfaces of D-4-1, D-3-3, and D-4-3, the other four soil samples of the same type showed no change. Analyzing the cause, the problem may be attributed to local variations in individual soil samples. Therefore, it can be concluded that freeze-thaw cycles were not the main cause of soil damage at the Gaochang Ancient City Dafosi Site. Furthermore, it is not difficult to observe that the addition of chemical reinforcing agents did not form a "hard shell" with significantly different strengths and deformation capacities on the soil surface. To further investigate the damage to the soil at this site under conditions where water content may change, all soil samples were rearranged into 5 groups. Water was added to the 5 groups at concentrations of 5%, 10%, 15%, and 20%, respectively, while the last group remained in its original state. After adding water to each group of samples, they were tightly wrapped in plastic bags and placed in a constant temperature incubator for 24 hours. To save money, this experiment simulated the average temperature of the four seasons of a year over a 4-hour period. The experimental temperature progression curve (II) is available in [link / details]. Figure 20 The test results after two freeze-thaw cycles are shown in Table 4.4.

[0138] Table 4.3 Results of freeze-thaw test under initial conditions

[0139]

[0140]

[0141] Table 4.4 Results of freeze-thaw experiments after adding initial moisture content

[0142]

[0143]

[0144] As shown in Table 4.4, the likelihood of soil sample damage increases with gradually increasing moisture content. Although samples D-2-5, D-3-5, D-5-5, D-6-5, D-5-4, and D-6-4 developed cracks at the bottom during the first freeze-thaw cycle, these cracks occurred after water was added. Due to the water-resistance of the reinforced soil, it was difficult for the soil to absorb water, and the remaining water accumulated inside the plastic bag, soaking the soil for 24 hours. Under the soil's own shrinkage, cracks appeared on the bottom surface. Since most of the water in the soil had evaporated during the first high-low temperature cycle, the soil showed virtually no significant changes during the second freeze-thaw cycle.

[0145] In summary, the above experiments clearly demonstrate that the soil reinforced with BS-10 series reinforcing agents exhibits no obvious "crust" phenomenon on its surface. Under conditions of low moisture content, the reinforced soil samples show better freeze-thaw resistance than the undisturbed samples.

[0146] In summary, the simulated earthen archaeological site rammed earth test wall prepared by this invention can provide a scientific and reasonable technical means for the protection of earthen archaeological sites and provide reliable test specimens for the research and development of protection technologies.

[0147] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for constructing a simulated rammed earth test wall based on original defects in an earthen archaeological site, characterized in that, Includes the following steps: Step 1: Identify the defects of the earthen site to be studied and prepare materials. Prepare rammed earth materials, disease simulation materials, and mold equipment based on the earthen site to be studied; Step 2: Mold assembly and defect marking Assemble the wooden template, mark the layer lines on the inside of the template, mark the direction of the cracks and the division of the erosion area according to the current status of the disease of the soil site to be studied, pre-embed foam blocks at the bottom to simulate foundation erosion, and pre-embed thin wooden strips to simulate cracks in combination with the actual disease. Step 3: Layered compaction Layer by layer, 15cm thick, and spread soil into the wooden template. Each layer is tamped 6 times. Diluted glutinous rice juice is brushed between layers and the surface is leveled. The top layer is the weathering layer, which is spread with soil, lightly tamped 4 times, and then leveled. Step 4: Processing of fissure defects Extract the thin wood strips and create cracks based on the actual disease. To simulate crack expansion, use an awl to create branches at the ends. If it is a regular crack, use a cutting machine to create grooves. Step 5: Treatment of erosion defects Remove the bottom foam block, correct the edge position to "dog tooth shape", and combine it with the actual situation to form an eroded cavity; Step 6: Processing of weathering defects Based on the actual disease, the surface of the rammed earth wall was sandblasted to form a weathered layer. Then, a 5% Na2SO4 solution was sprayed and soaked for 24 hours and dried for 48 hours. This process was repeated three times to induce efflorescence on the surface of the rammed earth wall. Step 7: Treatment of Rain Erosion Damage A rotating rain shower head was installed on the top of the rammed earth test wall to simulate the erosion of heavy rain until a gully was formed at the bottom of the rammed earth wall. Step 8: Northwest Environmental Simulation (1) Strong wind erosion simulation: An axial flow fan is arranged on one side of the rammed earth test wall. Combined with the environment of the rammed earth wall to be studied, the maximum wind speed is continuously blown, and wind and sand are combined to create wind erosion pits. (2) Strong sunlight simulation, in a xenon lamp aging chamber (1.2kW / m²) 2 Irradiate at 60℃ for 12 hours daily for 15 days to induce surface cracking. (3) Strong salt accumulation simulation: 1.5% NaCl + Na2SO4 mixed salt was mixed in the soil at the bottom of the rammed earth wall. After 3 dry and wet cycles, a salt crystal layer with a thickness of 10 to 15 mm was formed at the base of the wall.

2. The method for constructing a simulated rammed earth test wall based on original defects of an ancient earthen site according to claim 1, characterized in that: The rammed earth material is the original soil surrounding the site to be studied, with a moisture content of 15% to 18%, mixed with 5% glutinous rice juice and 1% alum.

3. The method for constructing a simulated rammed earth test wall based on original defects of an ancient earthen site according to claim 1, characterized in that: The disease simulation materials include thin wooden strips, foam blocks, and Na2SO4. The wooden strips are 100mm long and are used to create through cracks; the foam blocks are 10×15×5cm in size and are used to create erosion cavities.

4. The method for constructing a simulated rammed earth test wall based on original defects of an ancient earthen site according to claim 1, characterized in that: The mold equipment includes a detachable wooden template, a sandblasting machine, and an artificial rain system; the wooden template is 2×1.5×0.5m in size, with layer lines and pre-set defect locations marked every 15-20cm on the inner side of the template; the sandblasting machine has a pressure of 0.3MPa; the artificial rain system has a rotatable nozzle.

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