Modified material for earthen archaeological site disease repair and repair effect evaluation method thereof

Abstract

The invention discloses a modified material for earthen archaeological site disease repair and a repair effect evaluation method thereof, and relates to the technical field of earthen archaeological site repair, the modified material comprises a silicon-calcium-based modified material based on metakaolin (A), calcium hydroxide (C) and silica fume (S) and an optimal ratio thereof, a comprehensive engineering performance test proves the feasibility of the silicon-calcium-based modified material in earthen ruins disease repair, the optimal ratio of A to C to S of the finally obtained ACS modified soil is 1: 2: 4, the added ACS modified material can generate a remarkable pozzolanic reaction with the ruins soil, and the denudation resistance and long-term durability of the original ruins soil are improved.

Description

Technical Field

[0001] This invention relates to the field of earthen site restoration technology, and in particular to modified materials for the restoration of earthen site defects and methods for evaluating their restoration effects. Background Technology

[0002] Cultural relics are symbols of human civilization, possessing significant historical, scientific, artistic, social, cultural, and emotional value. With the accelerating pace of human civilization, many sites of human civilization are on the verge of disappearing.

[0003] There are many types of materials for the repair of damage to earthen sites, and different modified materials have different repair effects. Previous studies have focused more on the short-term effects of modified materials in the repair of earthen sites. Due to the characteristics of the cultural relics protection industry and the importance of earthen sites themselves, it is difficult to conduct experiments on the earthen sites themselves. There is still a lack of exploration on the long-term weather resistance of modified materials in the repair of earthen sites.

[0004] Therefore, there is an urgent need for a silicon-calcium based composite modified repair material. The optimal ratio and comprehensive engineering performance were obtained through indoor tests. Furthermore, the feasibility of this type of silicon-calcium based modified material in the repair of earthen sites was verified based on model tests and earthen site test sections, in order to provide a scientific reference for the repair materials of similar earthen sites. Summary of the Invention

[0005] To address the aforementioned issues, this application proposes a modified material for the restoration of soil archaeological sites, wherein the modified material is a silicon-calcium based modified soil; The modified materials include metakaolin, calcium hydroxide, and silica-modified soil; The metakaolinite comprises 44% Al2O3 and 52% SiO2; The modified material comprises metakaolin A, calcium hydroxide modified clay C, and silica fume modified clay S in the following mass ratio. Φ M1 The ratio is: A:C:S = 1:2:4; Among them, the material mass ratio of modified soil is defined. Φ as follows: ; In the formula: M 1 represents the mass (g) of the modified material; M 2 represents the mass (g) of the raw soil. When there is one or more modifying materials, the mass ratio between the modifying materials can be expressed as follows: Φ M1 .

[0006] Preferably, during the preparation process, the modified material is first mixed and stirred evenly, then added to the plain soil and mixed evenly, and finally the required mass of water is added; When preparing modified soil with a certain moisture content, follow the expression below: ; ; In the formula: m w The mass (g) of water required to be added to the soil; m 0 represents the mass (g) of the air-dried soil; ω 0 represents the moisture content (%) of the air-dried soil; ω ´ represents the required moisture content (%) for the soil sample; m The mass (g) of soil required for sample preparation; ρ d The required dry density (g / cm³) for sample preparation 3 ); V The volume of the sample preparation device (cm²) 3 ).

[0007] In summary, the modified material for the restoration of earthen archaeological sites and its method for evaluating the restoration effect of this invention have the following advantages compared with traditional technologies: 1. A silicon-calcium based modified material ACS and its optimal ratio scheme for repairing soil archaeological sites were developed. Through microstructural tests, it was found that new cementing substances such as ettringite and calcite in ACS-modified soil enhance the compactness of the soil, reduce porosity, and thus improve the mechanical properties of the modified soil. 2. The addition of ACS modified materials increased the optimum moisture content by 4.5%, decreased the maximum dry density by 22%, increased cohesion by 3.4 times, improved erosion resistance by 40 times, and reduced the disintegration rate and disintegration percentage to only 2.7% and 6.8% of that of the archaeological soil, respectively. The unconfined compressive strength was 6.1 times that of the archaeological soil. Moreover, the bonding effect of ACS modified soil slurry was more significant, with capillary water lift height of about 61% of that of the archaeological soil. With the increase of freeze-thaw cycles, a significant volcanic ash reaction occurred between ACS modified materials and archaeological soil, which improved the cementation strength between soil particles, reduced interparticle porosity, enhanced the cohesion of soil particles, and further improved freeze-thaw resistance, which is more conducive to the long-term structural stability of the earthen archaeological site. 3. A model test was constructed to assess the repair effect of earthen archaeological sites and an evaluation method based on cracks was developed.

[0008] The technical method of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0009] Figure 1 This is the pre-crack repair test procedure. Figure 1 In the middle (a), the angle is 45°. Figure 1 (b) is 0°. Figure 1(c) is 90°. Figure 1 (d) is the die. Figure 1 (e) represents crack repair; Figure 2 This is a color difference test analysis method; Figure 3 The results of unconfined compressive strength tests on different modified soils are as follows: Figure 3 In Figure (a), the qu-Φ curve is shown for the single-doped modified material. Figure 3 (b) represents the two-component modified material. q u - Φ M1 curve( Φ =20%), Figure 3 (c) represents the two-doped modified material. q u - Φ curve, Figure 3 (d) represents the three-component modified material. q u - Φ M1 curve( Φ =20%), Figure 3 In the middle (e), the range parameter for different modified materials is represented. Figure 3 (f) is Φ M1 Parameters for modified materials q u The influence curve; Figure 4 Strength recovery rate for repairing pre-cracks with different modified soils δ ; Figure 5 The color difference between plain soil and modified soil; Figure 6 XRD test results for different modified soils; Figure 7 The results of microstructure scanning tests on different modified soils are as follows. Figure 7 (a) is plain soil. Figure 7 (b) is ACS-modified soil. Figure 7 (c) represents AC-modified soil. Figure 7 (d) is CS-modified soil. Figure 7 (e) represents the microstructure parameters of different modified soils; Figure 8 The results of CT scans of P and ACS. Figure 8 In the middle (a), the Avizo 3D reconstruction images are shown for different soil types. Figure 8 In (b), P and ACS porosity are represented. Figure 9Capillary lift height curves for plain soil and ACS modified soil; Figure 10 The cumulative disintegration time curves are for plain soil and ACS modified soil; Figure 11 The disintegration characteristics of plain soil and ACS modified soil under static water immersion; Figure 12 The disintegration characteristics of plain soil and ACS modified soil under natural conditions; Figure 13 The disintegration rates and disintegration ratios of the plain soil and the ACS-modified soil are given. Figure 13 In the middle (a), the erosion rate is represented. Figure 13 (b) represents the erosion ratio; Figure 14 The results are from freeze-thaw cycle tests on plain soil and ACS-modified soil. Figure 14 (a) shows the experimental results of unconfined compressive strength of different soils. Figure 14 (b) shows the results of the internal friction angle and the number of freeze-thaw cycles. Figure 14 (c) shows the results of cohesion and freeze-thaw cycle count; Figure 15 This is a hierarchical structure model diagram; Figure 16 Repair experiments were conducted on different disease models. Figure 16 (a) shows the model preparation. Figure 16 In (a), (1) represents the model installation. Figure 16 (a) In (2) the model is solidified. Figure 16 (a) In (3) the model is solidified; Figure 16 (b) shows the preparation of a diseased model (placed in a natural environment for 1 year). Figure 16 (b) In (1) the collapse disease, Figure 16 (b) In (2) the disease is erosion. Figure 16 (b) In section (3), cracks are the disease. Figure 16 (c) represents the disease repair model. Figure 16 (c) (1) is the collapse repair model Figure 16 (c) (2) is the peeling repair model Figure 16 (c)(3) represents the crack repair model; Figure 16 (d) is a disease repair model (stored for 1 year after repair). Figure 16 (d) In section (1) the collapse repair is performed. Figure 16 (d) In (2) the exfoliation repair type, Figure 16 (d) In (3) the crack repair is shown. Figure 16 (e) shows the comparison curves of the repair effect. Detailed Implementation

[0010] The technical method of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application.

[0011] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0012] Techniques, systems, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the instruction manual.

[0013] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0014] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0015] A certain city is an important historical site located in a certain city of a certain province. The soil sample used in the experiment was taken from the rammed earth of the city wall. The optimum moisture content of the rammed earth of this ancient city wall... ω op =13.3%, maximum dry density ρ dmax =1.88g / cm 3 The main physical parameters of the rammed earth samples are shown in Table 1. The modified materials used in this experiment are metakaolin (M), calcium hydroxide (C), and silica fume (S), and their specific characteristics are as follows: (1) Metakaolin, made by calcining and dehydrating kaolin (model: JYB-80). The particle size is 4000 mesh, the particles are small, and the whiteness is ≥92%. The main component of metakaolin is anhydrous aluminum silicate (Al2O3·2SiO2).

[0016] (2) The microsilica powder is white in appearance and has a refractoriness >1600℃. Density: 1600~1700 kg / m³ 3 Its average pH is neutral. The average particle size of the microsilica powder is 0.1~0.15 μm, and the specific surface area is 15~27 m². 2 / g.

[0017] (3) Calcium hydroxide (hydrated lime) is mainly composed of Ca(OH)2. The finished product is a fine white powder, strongly alkaline, and has a density of 2.24 g / cm³. 3 .

[0018] Table 1 Physical and mechanical parameters of the soil at the archaeological site

[0019] Note: w- Moisture content ρ d -Dry density, G s -Particle specific gravity, W l -Liquid limit, W P -Plastic limit, I P - Plasticity index, c - Cohesion, -Internal friction angle, E s -Compression modulus.

[0020] Example 1 The archaeological site soil (plain soil) used in this paper was taken from the exfoliated loess of the rammed earth wall. The modified material to be used in this experiment is metakaolin, whose main components are 44% Al2O3 and 52% SiO2; calcium hydroxide (abbreviated as C) and silica fume. In this experiment, the above modified materials were mixed in pairs or in groups of three and then mixed with the archaeological site soil. Different modified soil ratio tests were carried out. The names and codes of the modified soil are as follows: plain soil (P), metakaolin modified soil (A), calcium hydroxide modified soil (C), silica fume modified soil (S), metakaolin + calcium hydroxide modified soil (AC), metakaolin + silica fume modified soil (AS), calcium hydroxide + silica fume modified soil (CS), and metakaolin + calcium hydroxide + silica fume modified soil (ACS).

[0021] Define the material mass ratio of modified soil Φ as follows: ; In the formula: M 1 represents the mass (g) of the modified material; M 2 represents the mass (g) of the raw soil. When there is one or more modifying materials, the mass ratio between the modifying materials can be expressed as follows: Φ M1 .

[0022] When preparing modified soil with a certain moisture content, follow the formula below: ; ; In the formula: m w The mass (g) of water required to be added to the soil; m 0 represents the mass (g) of the air-dried soil; ω 0 represents the moisture content (%) of the air-dried soil; ω ´ represents the required moisture content (%) for the soil sample; m The mass (g) of soil required for sample preparation; ρ d The required dry density (g / cm³) for sample preparation 3 ); V The volume of the sample preparation device (cm²) 3 ).

[0023] Based on the compaction characteristics of the rammed earth from the archaeological site, the dry density and moisture content of both the plain soil and the modified soil in the experiment were uniformly controlled as follows: ρ d =1.88g / cm 3 , ω =13.33%. Modified material dosage. Φ ≤20%. To determine the optimal mix ratio of modified soil, the unconfined compressive strength of the modified soil, the bonding characteristics of the repair material, and the color difference were used to comprehensively determine the optimal mix ratio of modified soil.

[0024] Based on past experience, the test schemes for the unconfined compressive strength of modified soils with different mix proportions are shown in Table 2.

[0025] Table 2. Test scheme for unconfined compressive strength of modified soil

[0026] Note: For example, 7:3 in AC means A:C = 7:3 or Φ M1 =7:3.

[0027] Table 2 shows the different proportions. Φ Unconfined compressive strength of modified soil at 28 days age under single-, two-, and three-admixture schemes. q u Curve Figure 3 .

[0028] (1) The test results of the single-doped modified material are as follows Figure 3 As shown in (a), C-modified soil ( q u =903.62kPa) is plain soil ( q u =282.46kPa) is 2.49 times that of modified soil A ( q u =483.04kPa) is 1.71 times the strength of plain soil; S modified soil ( q u The strength of C-modified soil (516.35 kPa) is 1.82 times that of plain soil. When mixed with a single modifier, C-modified soil has the best effect on improving its strength.

[0029] (2) The test results of the two-component modified materials are as follows: Figure 3 As shown in (b), the unconfined compressive strength of AC and CS modified soils both show a trend of first increasing and then decreasing as the ratio of the two decreases, with the highest values ​​for A:C=5:5 and C:S=3:7. q u The strength reaches its maximum; a comparison shows that appropriately adding modified materials to plain soil can improve its strength because: when the fine particles in the modified materials fill the pores of the plain soil, they increase the bonding and frictional strength between the particles; from Figure 3 (c) It can be seen that when its total content Φ When the content is 20%, the unconfined compressive strength of the three types of modified soils, ranked from highest to lowest, is as follows: CS modified soil ( q u =1562kPa)>AC modified soil ( q u =1174kPa)>AS modified soil ( q u =549.7kPa), therefore, the optimal combination of the two admixtures is CS modified soil, and the optimal ratio is C:S=3:7.

[0030] (3) The test results of the three-component unconfined compressive strength are as follows: Figure 3 As shown in (d), range analysis was used to compare the influence of different modified soils on unconfined compressive strength. The results of the range analysis are as follows: Figure 3 As shown in (e), the influence of the three modifying materials on the unconfined compressive strength of ACS modified soil was obtained as follows: metakaolin (A) > silica fume (S) > calcium hydroxide (C). Furthermore, according to the analysis of variance, the optimal ratio of the three modifying materials was determined. Φ M1 The effect curve on unconfined compressive strength is shown in the figure. Figure 3 (f) When the A:C:S mix ratio is 1:2:4, the unconfined compressive strength of the ACS modified soil reaches its maximum, and 1:2:4 is considered the optimal mix ratio. To verify its rationality, two additional tests were conducted with mix ratios of 1:2:3 and 1:2:4. The results are shown in […]. Figure 3 (d) When A:C:S=1:2:4, Φ When =20%, q u =1707.8 kPa, reaching its maximum.

[0031] The results of pre-crack repair tests were obtained by repairing through-crack samples at different angles (45°, 0°, 90°) using modified soil grouts with different water-to-solid ratios of 33%, and the strength recovery rate was obtained. δ like Figure 4 As shown, the pre-crack repair test procedure is as follows: Figure 1 As shown.

[0032] Depend on Figure 4 It can be seen that, for pre-cracks with different inclination angles, the strength of the samples repaired with modified material grout can reach up to 90% of that of intact soil samples, with a strength recovery rate of [missing information]. δ The percentages from highest to lowest are: ACS (90%) > C (83%) > CS (81%) > AC (79%) > P (69%). This shows that ACS-modified soil has a better remediation effect than other modified soils, being 1.30 times that of plain soil.

[0033] The color difference test results obtained by the color difference test showed the color difference value Δ between the four types of modified soil and plain soil. E See Figure 5 The color difference test method procedure is as follows: Figure 2 As shown. By Figure 5 It can be seen that the color difference between modified soil and plain soil, from largest to smallest, is: C > CS > AC > ACS, with ACS modified soil having the smallest color difference between it and plain soil. Δ E =3, the color difference is not discernible to the naked eye.

[0034] The optimal mix proportion of modified soil was determined based on the aforementioned unconfined compressive strength test, pre-crack repair test, and color difference test, and compared with that of plain soil. The specific determination method is as follows: when the unconfined compressive strength of a certain modified soil... q u To achieve maximum strength recovery rate after crack repair δ The optimal mix ratio is defined as the modified soil with a color difference Δ≤3 exceeding 95% and a significant change in microstructure compared to the original soil, along with its corresponding mix ratio. The four characteristics of different modified soils are categorized into four levels: excellent, good, medium, and poor, as summarized in Table 3. Comparative analysis shows that the final score for ACS modified soil is excellent. Based on the optimal mix ratio test, the optimal modified soil is ACS modified soil, with an optimal mix ratio of A:C:S = 1:2:4.

[0035] Table 3. Engineering performance evaluation of different modified soils

[0036] Example 2 To compare and analyze the differences in microstructure between silicon-calcium-based modified soil and the original site soil, and to reveal their solidification mechanism, XRD diffraction tests were conducted on ACS-modified soil and the original site soil. Figure 6 As shown, the SEM scanning experiment is as follows: Figure 7 As shown in the figure and CT scan test Figure 8 As shown.

[0037] XRD diffraction results showed that the soil from the archaeological site contained minerals such as quartz, albite, and muscovite, as well as non-mineral components such as trans-butenedionitrile (C4H2N) and hydrogen sulfide ((NH4)SH). After ACS modification, in addition to retaining the original quartz and albite components, new compounds such as ettringite were formed due to the reaction with volcanic ash. This indicates that the ACS-modified material enhanced the cohesion between soil particles.

[0038] Depend on Figure 3 From (a) to (e), we can see that the porosity from largest to smallest is: P > C > AC > CS > ACS. It can be seen that the ACS modified soil is the best at improving porosity, with a porosity of only 51.52% of that of the plain soil. The ACS has the largest directional probability entropy value, indicating that the arrangement of pores is relatively disordered. The CS and ACS modified soils have the largest values, indicating that the pore boundary morphology is more complex and the cementation type of the soil skeleton particles is more diverse, which is conducive to improving the soil strength.

[0039] pass Figure 4 Comparative analysis revealed a significant reduction in the number of pores and throats in ACS-modified soil compared to plain soil. This change enhances the hydrophobicity of ACS-modified soil, making it more difficult for water molecules to penetrate the interconnected pore-throat structure, suggesting that ACS-modified soil possesses stronger resistance to water erosion. The overall porosity of ACS-modified soil is lower than that of plain soil, indicating that the appropriate addition of metakaolin and silica fume can effectively reduce porosity, limit throat formation, and thus significantly reduce the permeability of ACS-modified soil.

[0040] Example 3 In order to comprehensively evaluate the engineering performance of modified soil in the restoration of soil archaeological sites, from the perspective of practical engineering, further indoor and model tests were conducted on the weather resistance of plain soil and ACS modified soil.

[0041] (1) Disintegration test under static water immersion: Taking the test results of plain soil and ACS modified soil with a curing period of 28 days as an example, the hydrostatic disintegration time curves of the two within 15 minutes are shown below. Figure 10 The disintegration characteristics of the samples at different time periods are shown in Table 6.

[0042] Table 6 shows that after soaking in water, the plain soil developed bubbles on the surface within 6 minutes, and the soil at the edges continued to erode and fall off. After 15 minutes, the entire sample disintegrated into mud. The ACS modified soil sample showed slight bubble formation in the first 3 minutes. However, after soaking for 60 minutes, the sample remained intact except for a small amount of detachment at the edges. The disintegration rate of the ACS modified soil... v ACS = 0.20 g / min, while the disintegration rate of the plain soil vP = The disintegration resistance of ACS modified soil is 7.4 g / min, which is only 2.7% of that of plain soil. This shows that the disintegration resistance of ACS modified soil is significantly stronger than that of plain soil.

[0043] (2) Disintegration test under natural conditions: Calculate the erosion ratio of plain soil and ACS modified soil under natural conditions for 200 days at different time periods. η and erosion rate ν s ,See Figure 13 .

[0044] Depend on Figure 13 It can be seen that the ACS-modified soil exhibits significantly better erosion resistance than the plain soil. The cracks in the plain soil samples gradually increased from 14 days to 200 days, progressing from the top to the entire surface until complete detachment and spalling. In contrast, no visible cracks appeared in the ACS-modified soil within 200 days of storage. Figure 13 (b) It can be seen that after 200 days, the total erosion ratio and erosion rate of ACS modified soil were only 1.9% and 0.01% / d, while those of plain soil were 76% and 0.38% / d. Compared with plain soil, the erosion resistance of ACS modified soil is about 40 times that of plain soil, which significantly improves the erosion resistance of soil.

[0045] (3) Disintegration test under dynamic water scouring: As shown in Table 4, after 60 seconds of scouring, the original soil exhibited significant erosion under the influence of flowing water, while the appearance of the ACS-modified soil remained largely unchanged. The average disintegration rate of the original soil at different ages was calculated. - ζ= 16%, disintegration rate of ACS modified soil - ζ= 1.1%, ACS modified soil has significant anti-disintegration characteristics under dynamic water conditions.

[0046] Table 4. Disintegration rates of plain soil and ACS-modified soil

[0047] The soil from the archaeological site was left outdoors for a long time. Due to the seasonal temperature changes, the soil developed cracks and froze. In order to further study the deterioration mechanism of the plain soil and ACS modified soil under freeze-thaw cycles, freeze-thaw cycle tests were carried out as shown in Table 5.

[0048] Table 5 Unconfined compressive strength and direct shear strength under freeze-thaw cycles.

[0049] To clarify the correlation between freeze-thaw tests and the mechanical properties of ACS-modified soil, direct shear tests and unconfined compressive strength tests were conducted. The test results are as follows: Figure 14 As shown in (a~c).

[0050] The research results show that: in the initial freeze-thaw ( N During the freeze-thaw cycle period (0 to 3), the unconfined compressive strength of ACS modified soil decreased by 1256 kPa from 1626 kPa, while the cohesion and internal friction angle decreased by 22.83% and 8.58%, respectively. However, when the number of freeze-thaw cycles increased to 4 to 20, the unconfined compressive strength (… q u The soil exhibits a significant rebound in hardness; the fundamental reason being that as the thawing time lengthens, the unreacted modified materials initiate a pozzolanic reaction at high temperatures, effectively reducing interparticle porosity and enhancing soil cohesion. The freeze-thaw resistance of ACS-modified soil is thus demonstrated.

[0051] Example 4 Based on the test results, such as Figure 9 As shown, the capillary water rise height of the plain soil is 90cm, and the capillary water rise height of the ACS modified material is 55cm. Based on engineering experience and test results, the capillary water rise height is divided into four levels, A to D, which represent the impact of capillary water rise on the weather resistance of the soil site. The greater the capillary water rise height, the worse its long-term weather resistance. A (extremely strong): 0~30cm; B (relatively strong): 30~60cm; C (relatively poor): 60~90cm; D (extremely poor): >90cm.

[0052] The disintegration rate refers to the speed at which soil separates from the overall structure of an earthen site under the action of still water immersion, that is, the mass or volume of particles separated from the earthen site per unit time.

[0053] The expression for the disintegration rate is: ; In the formula: v The disintegration rate is expressed in g / min. M ud The mass (g) of undisintegrated loess; m a The reading is for the weighing sensor (g). ρ sat The saturated density of loess (g.cm³) -3 ); ρ w The density of pure water (1.0 g·cm³) -3 ); M d The mass (g) of loess; T The soil sample disintegration time (min) is given.

[0054] The disintegration characteristics of plain soil and ACS modified soil under water immersion and natural environment are as follows: Figure 11 and Figure 12As shown, based on the test results, the disintegration rate of the plain soil is 7.4 g / min, and the disintegration rate of the ACS modified material is 0.2 g / min. Combined with the indoor test results, the disintegration rate index is divided into four levels. The faster the disintegration rate, the worse its long-term weather resistance. A (extremely strong): 0~0.1 g / min; B (relatively strong): 0.1~1.0 g / min; C (relatively poor): 1.0~10 g / min; D (extremely poor): >10 g / min.

[0055] The erosion ratio refers to the ratio of the mass of the sample that has fallen off or detached due to natural conditions to the original mass, expressed as a percentage.

[0056] The expression for the erosion ratio is: ; In the formula: η Erosion ratio (%); m d Equivalent erosion mass (g); m 0 represents the initial soil sample mass (g).

[0057] Based on the test results, the erosion ratio of the raw soil was 76%, and the disintegration rate of the ACS modified material was 1.9%. Combined with the results of the indoor test, the erosion ratio index was divided into four levels. The larger the erosion ratio, the worse its long-term weather resistance. A (extremely strong): 0~2%; B (relatively strong): 2~20%; C (relatively poor): 20~70%; D (extremely poor): >70.0%.

[0058] The erosion rate refers to the ratio of the erosion ratio to the erosion period under natural conditions, and the unit is % / d.

[0059] The expression for the erosion rate is: .

[0060] Based on the test results, the erosion rate of the raw soil was 0.38%, and the disintegration rate of the ACS modified material was 0.01% / d. Combining the results of the indoor test, the erosion rate index was divided into four levels: A (extremely strong): 0~0.01% / d; B (relatively strong): 0.01~0.10% / d; C (poor): 0.1~1.0% / d; D (very poor): >1.0% / d.

[0061] Using quality loss rate ζ To reflect the soil's resistance to disintegration under dynamic water conditions, the mass loss rate is determined by the mass lost due to dynamic water disintegration. m 1- m 2) Compared with the original soil sample quality ( m 1) Expressed as a ratio.

[0062] The expression for the mass loss rate is: ; In the formula: m1 represents the original soil sample mass (g); m 2 represents the mass (g) of the soil sample from the dynamic water test.

[0063] Based on the test results, the mass loss rate of the raw soil was 16%, and the mass loss rate of the ACS modified material was 1.1%. Combined with the results of the indoor test, the erosion rate index was divided into four levels: A (extremely strong): 0~0.2%; B (relatively strong): 0.2~2%; C (poor): 2~20%; D (very poor): >20%.

[0064] The compressive strength enhancement factor refers to the ratio of the maximum unconfined compressive strength of the modified material to the unconfined compressive strength of the original soil. A (extremely strong): >5; B (relatively strong): 2~5; C (relatively poor): 1~2; D (extremely poor): <1.0.

[0065] The shear strength enhancement factor refers to the ratio of the maximum shear strength of the modified material to the shear strength of the original soil. A (extremely strong): >3; B (relatively strong): 2~3; C (relatively poor): 1~2; D (extremely poor): <1.0.

[0066] Based on the above evaluation indicators, a preliminary comprehensive evaluation standard can be established. However, the standard still needs to be established based on the actual situation, which will make it more targeted. The specific division is shown in Table 6.

[0067] Table 6 Risk Factor Classification Table

[0068] The specific content of determining the risk weight coefficients of physical indicators using the analytic hierarchy process includes: Based on the experimental physical indicators, the relationships between various influencing factors are clearly defined, and a hierarchical analysis structure model for risk assessment is constructed, such as... Figure 15 As shown; Preset elements The values ​​are determined with reference to the importance scaling table. A hazard analysis is performed on the risk factors, and pairwise comparisons are made between factors at the same level to determine the magnitude of their impact on the weather resistance index, thus constructing a pairwise judgment matrix. , The importance weights of elements relative to their criteria are calculated from a single judgment matrix using the square root method. After constructing the judgment matrix A, the largest eigenvalue of judgment matrix A is obtained. ; Its feature vector W Normalization yields the importance weights of each factor; To avoid contradictions in the determination of the importance of matrix factors, a consistency check is required.

[0069] Table 7 Physical Index Judgment Matrix

[0070] Based on the experience and judgment of multiple experts, and following the steps described above, the judgment matrices for each criterion level (Table 7), the judgment matrices for the second-level indicators (Table 8), and the judgment matrices for the third-level indicators (Table 9) were weighted, and the final weight allocation of the evaluation indicators is shown in Table 10.

[0071] Table 8. Criterion Layer Judgment Matrix

[0072] Table 9 Mechanical Index Judgment Matrix

[0073] Table 10 Summary Table of Rating Indicator Weight Allocation

[0074] After determining the weight coefficients of the seven indicators using the AHP method, a questionnaire survey can be conducted to determine the final score and evaluate the overall performance.

[0075] Example 5 Expert scoring and evaluation levels: 1. Construct an expert survey questionnaire.

[0076] First, an expert questionnaire needs to be constructed. The questionnaire mainly consists of two parts: scoring of physical and mechanical indicators. This questionnaire is sent to the expert database through the Wenjuanxing platform. After expert scoring, sample data is obtained, and all samples are divided into four score categories: 0-20 points (very unimportant), 30-40 points (moderately important), 50-70 points (important), and 80-100 points (very important). Scores are then assigned to each of the seven indicators. The identity of each respondent and their years of experience in the relevant field are also obtained. The collected data is cleaned to remove invalid questionnaires and outliers. Statistical software is used to analyze the data and calculate the average score for each indicator.

[0077] 2. Determining indicator weights: Step 1: The formula for calculating the weighted score of a single indicator is as follows: ; in S z It is expressed as a weighted average score of individual indicators; S m Indicates the first m Scoring of each indicator m The number of scoring items; ; in S A This is expressed as the average score of all indicators; S nm Represented as the first n Peoplem Scoring of each indicator n For the number of people who gave the rating, m The number of scoring items; Step 2: Standardization. This step adjusts the data to make comparisons between different indicators more equitable. Common standardization methods include Z-score standardization, which standardizes the data by subtracting the mean and dividing by the standard deviation.

[0078] Step 3: The normalization formula is as follows: ; 3. Calculation of comprehensive weight evaluation.

[0079] The weights of the seven indicators were obtained through a questionnaire survey, as shown in Table 11.

[0080] Table 11 Summary Table of Rating Indicator Weight Allocation

[0081] Among them: capillary lift height ( W The weighting coefficient for 1) is Q 1 = 0.333; Disintegration rate under static water immersion ( W The weighting coefficient for 2) is Q 2 = 0.111; Erosion ratio under natural conditions ( W The weighting coefficient for 3) is Q 3 = 0.123; Erosion rate under natural conditions ( W The weighting coefficient for 4) is Q 4 = 0.101; Mass loss rate under dynamic water erosion ( W The weighting coefficient for 5) is Q 5 = 0.056; compressive strength enhancement factor ( L The weighting coefficient for 1) is Q 6 = 0.223, shear strength enhancement factor ( L The weighting coefficient for 2) is Q 7 = 0.053.

[0082] Expert scoring weighting coefficient Q sum, , i The number of terms; Total score S , ; in S This is represented as the total score of the indicators after expert evaluation; Q i Represented as weighting coefficients, M i This is represented as the project evaluation score.

[0083] Based on the scoring, a relationship is established with the evaluation grades A, B, C, and D, as shown in Table 12.

[0084] Table 12 Quantitative Scores for Grade Classification

[0085] Taking the damage to a certain earthen site in Xi'an as an example; this area is located in Guanzhong, belonging to the warm temperate semi-humid monsoon climate zone, with four distinct seasons and simultaneous rainfall and heat. According to existing data, the average annual temperature in this area is about 13.3℃, ​​and the annual precipitation is about 604 mm, with rainfall mainly concentrated between July and September. Rainwater rapidly infiltrates along the cracks in the dense rammed earth layers. Based on field surveys and indoor tests, the following results were obtained: the capillary rise height after rain was 34.7 cm; the disintegration rate was 0.15; the erosion ratio was 1.05%; the erosion rate was 0.015% / d; the mass loss rate was 2.2%; after applying modified materials, the compressive strength enhancement coefficient of the site soil was 1.5; and the shear strength enhancement coefficient was 2.5. Based on the above-mentioned AHP (Analytic Hierarchy Process) and the comprehensive weighted evaluation standard of expert questionnaire survey, the above-mentioned earthen site was comprehensively evaluated, and the scores are shown in Table 13 below: Table 13 Scores

[0086] Using the total evaluation score S The formula calculates the score and then conducts a comprehensive evaluation of its weather resistance.

[0087] The calculation results show S =82.276 points (expert questionnaire survey method) and S =81.214 points (AHP analytic hierarchy process). Based on the two methods, the weather resistance level of this earthen site is B. Example Six Based on the scale of the remains, a steel plate model box with dimensions of base width × top width × height × longitudinal length × thickness = 0.375m × 0.225m × 0.6m × 0.4m × 10mm was developed. Figure 16 As shown in (a).

[0088] The models and repair effects for the above three types of diseases are as follows: (1) Collapse Damage Model Restoration. After the original site soil was rammed into shape, it was placed in the natural environment for 1.0 year. The collapsed parts were then created by artificial excavation. Figure 16 (b-1) was subsequently repaired using a method of patching with plain earthen bricks. ACS-modified grout was used as the mortar between the bricks. A 1.0-year model was observed after the repair. Figure 16 (d-1).

[0089] (2) Restoration of the erosion model. After the original site was rammed, a blower was used to carry sand for erosion, simulating the erosion damage on the model surface. Figure 16(b-2), subsequently, ACS slurry spraying was used to repair the surface erosion damage. The effect 1.0 year after repair was as follows: Figure 16 (d-2).

[0090] (3) Repair of cracked soil model. A soil model was prepared using the same method as the previous one, and two cracks, each 1 cm wide and 20 cm deep, were cut into it. See [link to relevant documentation]. Figure 16 (b-3) Cracks were repaired using ACS grout, and the results after 1.0 year were as follows: Figure 16 (d-3).

[0091] Depend on Figure 16 (e) It can be seen that the crack rate of the site model before restoration can reach up to 4.8%. After restoration with ACS modified soil, the crack rate of the earthen site model is significantly reduced. This indicates that the use of ACS modified materials can rapidly reduce the rate of damage to earthen sites caused by the external environment. ACS modified materials are suitable for the restoration of the three major types of diseases of earthen sites and can maintain long-term stability.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical methods of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical methods of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical methods to deviate from the spirit and scope of the technical methods of the present invention.

Claims

1. A modified material for the restoration of damaged earthen archaeological sites, characterized in that, The modified material is silicon-calcium based modified soil; The modified materials include metakaolin, calcium hydroxide, and silica-modified soil; The metakaolinite comprises 44% Al2O3 and 52% SiO2; The modified material comprises metakaolin A, calcium hydroxide modified clay C, and silica fume modified clay S in the following mass ratio. Φ M1 The ratio is: A:C:S = 1:2:4; Among them, the material mass ratio of modified soil is defined. Φ as follows: ； In the formula: M 1 represents the quality of the modified material; M 2 represents the mass of the raw soil. When there is one or more modifying materials, the mass ratio between the modifying materials is expressed as follows: Φ M1 .

2. The modified material for the restoration of earthen archaeological sites according to claim 1, characterized in that, During the preparation process, the modified materials are first mixed and stirred evenly, then added to the plain soil and mixed evenly, and finally the required amount of water is added. When preparing modified soil with a certain moisture content, follow the expression below: ； ； In the formula: m w The required mass of water to be added to the soil; m 0 represents the mass of the air-dried soil; ω 0 represents the moisture content of the air-dried soil; ω ´ represents the required moisture content of the soil sample; m The mass of soil required for sample preparation; ρ d The required dry density during sample preparation; V The volume of the sample preparation device.

3. The modified material for the restoration of earthen archaeological sites according to claim 2, characterized in that, The weather resistance of the modified material is determined by performance testing to obtain test physical indicators. The risk weight coefficients of physical indicators are determined using the analytic hierarchy process (AHP). A questionnaire survey based on the risk weight coefficient of physical indicators is used to determine the final score and obtain the indicator weight, and then to evaluate the overall performance. The physical indicators include capillary lift height, disintegration rate under static water immersion, erosion ratio under natural conditions, erosion rate under natural conditions, mass loss rate under dynamic water erosion, erosion rate under natural conditions, mass loss rate under dynamic water erosion, compressive strength enhancement coefficient, and shear strength enhancement coefficient.

4. The modified material for the restoration of earthen archaeological sites and the method for evaluating its restoration effect according to claim 3, characterized in that, The specific content of determining the risk weight coefficients of physical indicators using the analytic hierarchy process includes: Based on the experimental physical indicators, the relationships between various influencing factors are clarified, and a hierarchical analysis structure model for risk assessment is constructed. Preset elements The values ​​are determined with reference to the importance scaling table. A hazard analysis is performed on the risk factors, and pairwise comparisons are made between factors at the same level to determine the magnitude of their impact on the weather resistance index, thus constructing a pairwise judgment matrix. ; The importance weights of elements relative to their criteria are calculated from a single judgment matrix using the square root method, in the construction of the judgment matrix. A Next, calculate the judgment matrix. A Maximum eigenvalue ; Its feature vector W Normalization yields the importance weights of each factor.

5. The modified material for the restoration of earthen archaeological sites and the method for evaluating its restoration effect according to claim 4, characterized in that, The risk assessment hierarchical analysis structure model includes the target layer, criterion layer, indicator layer, and state layer; The target layer is the comprehensive weather resistance index of silicon-calcium-based modified soil; The criteria layer consists of physical and mechanical indicators; The indicator layer includes: Capillary lift height under physical parameters, disintegration rate under static water immersion, erosion ratio under natural environment, erosion rate under natural environment, mass loss rate under dynamic water erosion, erosion rate under natural environment, and mass loss rate under dynamic water erosion. The compressive strength enhancement factor and shear strength enhancement factor under mechanical properties; The state layers include levels A, B, C, and D.

6. The modified material for the restoration of earthen archaeological sites and the method for evaluating its restoration effect according to claim 5, characterized in that, The expression for the judgment matrix is: ； In the matrix, , .

7. The modified material for the restoration of earthen archaeological sites and the method for evaluating its restoration effect according to claim 6, characterized in that, Its feature vector W The normalized expression is: ； In the formula: A For the judgment matrix; To determine the matrix A The largest eigenvalue; W To determine the largest eigenvalue λ of a matrix max The corresponding feature vector is the weight vector.

8. The modified material for the restoration of earthen archaeological sites and the method for evaluating its restoration effect according to claim 7, characterized in that, The consistency test expression is: ； In the formula, To determine the matrix A The largest eigenvalue; n To determine the matrix A The order of; CR The proportion of random consistency; CI As a consistency indicator; RI This is the average random consistency index.

9. A method for evaluating the restoration effect of a modified material used for the restoration of damage to earthen archaeological sites, wherein the restoration process of the method uses the modified material for the restoration of damage to earthen archaeological sites as described in any one of claims 1-8, characterized in that... First, models of collapse disease, erosion disease, and crack disease are constructed; Based on the scale of the remains, a steel plate model box with dimensions of bottom width × top width × height × longitudinal length × thickness = 0.375m × 0.225m × 0.6m × 0.4m × 10mm was developed. The models and methods for recording the repair effects of the above three types of diseases are as follows: (1) Collapse disease model repair: After the original site soil was rammed into shape, the collapsed part was formed by artificial excavation. Then, the repair was carried out by the masonry method. ACS modified material grout was used as mortar between the bricks. The model was recorded 1.0 years after the disease repair. (2) Repair of erosion disease model: After the original site soil was rammed, sand was blown by a blower, and then ACS grout was sprayed to repair the surface erosion disease. The effect was recorded 1.0 year after repair. (3) Repair of crack disease model: Prepare a soil model and cut it into two cracks with an area of ​​1cm x 20cm. Repair the cracks with ACS grout and record the effect 1.0 year after repair.

10. The method for evaluating the restoration effect of a modified material for the restoration of damage to earthen archaeological sites according to claim 9, characterized in that, The model preparation process includes: The soil around the earthen site was selected, compacted, dried, and sieved. It was then rammed into 6 layers, each 10cm thick. Three TDR sensors were pre-embedded at the interface of each layer, for a total of 3 layers and 9 sensors.

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