A method for repairing earthen sites using bio-slurry

Abstract

The application discloses a method for repairing a soil site, and comprises the following steps: 1) selecting a soil body consistent with the soil site, and stirring the soil body with biological mud to prepare a repairing filler; 2) selecting bamboo strips soaked in salt water and treated by high-temperature cooking, and layering the bamboo strips to construct a support framework in a region to be repaired, and filling the repairing filler; and 3) spraying a biological treatment liquid on the region to be repaired and a surrounding surface of the region to be repaired multiple times, and curing. The application adheres to the principle of repairing an old thing to make it look like new, and repairs and reinforces the soil site by using biological mud based on a biological solidification technology, so that the repairing efficiency is high and the repairing effect is good. Meanwhile, the soil site is repaired by using the technology developed by the application, so that the region to be repaired has no obvious repairing traces, and the original historical deposits and features of the soil site can be well displayed.

Description

Technical Field

[0001] This invention relates to the field of earthen site restoration, specifically to a method for repairing earthen sites using biological mud. Background Technology

[0002] Earthen ruins are ancient Chinese residential architectural heritage and historical and cultural heritage, a crystallization of the wisdom of the ancient working people, possessing profound historical and artistic value. Due to the long-term influence of historical environment and human factors, the mechanical properties of the materials used in the construction of earthen ruins inevitably deteriorate to varying degrees. Furthermore, over the long course of history, earthen ruins inevitably suffer damage from various natural and human factors, resulting in cracking and even collapse. To preserve the historical memory of human civilization, effective protection of earthen ruins and restoration of damaged ruins based on the principle of "restoring the old as it was" have significant historical, scientific, and artistic value. However, limited by the current level of earthen ruin restoration technology, cultural relic protection units are currently forced to violate the principle of "restoring the old as it was" in ancient building restoration, using concrete and steel supports for reinforcement and restoration. Clearly, this method fails to showcase the original historical heritage and appearance of the earthen ruins. Therefore, this invention, adhering to the principle of "restoring the old as it was, without altering the original state" in cultural relic protection, proposes a method for restoring earthen ruins using biological mud slurry. Summary of the Invention

[0003] To address the problems encountered in the restoration of earthen sites, this invention proposes a method for repairing earthen sites using biological mud. This method is highly efficient and effective in restoring earthen sites, resulting in sites with strong erosion resistance and no obvious signs of repair, strictly adhering to the principle of "restoring the old as it was, without altering the original state" in cultural relic protection.

[0004] This invention is achieved through the following technical solution:

[0005] A method for repairing earthen sites using biological mud includes the following steps:

[0006] (1) Mix the urease-producing bacteria solution with the cementing solution and stir continuously. After standing, remove the supernatant to obtain biological mud.

[0007] (2) Prepare repair filler by mixing biological mud, cementing liquid and soil consistent with the soil body of the site to be repaired and stirring evenly.

[0008] (3) Select bamboo strips that have been soaked in salt water and steamed at high temperature to construct a support frame in layers in the area to be repaired and fill it with repair filler. Use the remaining repair filler to fill the gaps at the edges.

[0009] (4) Mix soybean enzyme solution with cementing solution to prepare biological treatment solution, and spray the biological treatment solution on the repaired area and its surrounding surface multiple times for maintenance.

[0010] Furthermore, the cementing solution is a mixture containing urea and CaCl2 at equimolar concentrations.

[0011] Further, in step (1), the volume ratio of the urease-producing bacterial solution to the cementing solution is 3:1 to 7:1, the concentration of the cementing solution is 4.0 mol / L, the stirring time is 8 to 12 h, and the standing time is 4 to 6 h.

[0012] Furthermore, in step (2), the mass ratio of cementing liquid, biological mud, and soil of the site to be repaired is 1:1:8~3:1:16; the concentration of the cementing liquid is 2.0~4.0 mol / L, and the moisture content of the repair filler is 25~30%.

[0013] Furthermore, the bamboo strips mentioned in step (3) are made by soaking newly cut bamboo strips in a 5%~10% salt solution for 1~2 days, air-drying them, and then steaming them in boiling water at 100℃ for 6~12 hours.

[0014] Furthermore, the compaction degree of the repair filler used to fill the area to be repaired shall not be less than 90%.

[0015] Further, in step (4), the soybean enzyme solution and the gelling solution are mixed at a volume ratio of 1:1, and the concentration of the gelling solution is 2.0 mol / L.

[0016] Further, the soybean enzyme solution mentioned in step (4) is obtained by stirring raw soybean powder with water for 30 minutes, letting it stand at 4°C for 12-24 hours, and separating the upper suspension. The amount of raw soybean powder used is 80-100 g / L.

[0017] Furthermore, in step (4), the spraying rate of the biological treatment solution is 2~2.5 L / m³. 2 / Second-rate.

[0018] Furthermore, in step (4), the biological treatment liquid is sprayed 3 to 7 times, with a 24-hour interval between each spray.

[0019] Ideally, the bamboo strips used should be freshly cut bamboo from the local area.

[0020] The principle of this invention is to prepare a bio-slurry with a high concentration of urease-producing bacteria using urease-producing bacteria solution and cementing solution. The urease-producing bacteria in the bio-slurry hydrolyze urea in the cementing solution and induce the formation of calcium carbonate crystals with cementing effect. At the same time, since the urease-producing bacteria are isolated from the soil, they can survive and reproduce in the soil for a long time, allowing the repair area to undergo repeated spraying and solidification treatment. By spraying the biological treatment solution (using soybean urease and cementing solution), the filled repair area is repeatedly reinforced, improving its durability and erosion resistance.

[0021] The beneficial effects of this invention are as follows: By introducing bio-slurry containing a high concentration of urease-producing bacteria into the soil through pre-mixing, the content of urease-producing bacteria per unit volume of soil is increased, resulting in higher biomineralization efficiency and in-situ treatment and reinforcement capabilities. Furthermore, areas repaired using the method described in this invention show no obvious repair traces, strictly adhering to the principle of "restoring the old as it was" in cultural relic restoration, and better showcasing the original appearance of the earthen site. Attached Figure Description

[0022] Figure 1 This is a flowchart illustrating the repair process of this invention.

[0023] Figure 2 Flowchart for the preparation of repair filler.

[0024] Figure 3 A schematic diagram of filling and compacting the repaired area.

[0025] Figure 4 This is a flowchart of the preparation process for biological treatment solution.

[0026] Figure 5 This image shows the effect of the sample surface being reinforced by spraying a biological treatment solution.

[0027] Figure 6 The disintegration rate diagrams are for Examples 1, 2, 3 and Comparative Examples 1, 2 after soaking in water for 24 hours.

[0028] Figure 7 The results of the erosion resistance test in water for Example 1 over 24 hours are shown.

[0029] Figure 8 The results are from the direct shear test in Example 1.

[0030] Figure 9 The results are from the direct shear test in Example 2.

[0031] Figure 10 The results are from the direct shear test in Example 3.

[0032] Figure 11 The results are from the direct shear test in Comparative Example 2. Detailed Implementation

[0033] To make the content of this invention easier to understand, the technical solution of this invention will be further explained below in conjunction with specific embodiments.

[0034] The urease-producing bacterial suspension used in this embodiment is *Bacillus pasteurellii* suspension. The *Bacillus pasteurellii* strain was isolated and extracted from soil and purified and screened using the conventional streak plate method to obtain the mother culture. The obtained strain was inoculated into YE-NH4 liquid medium for expansion culture. The medium composition included: yeast 20 g / L, ammonium chloride (NH4Cl) 15 g / L, and nickel chloride (NiCl2) 0.025 mM. The mother culture was inoculated into an Erlenmeyer flask at a volume ratio of 1:1000 and placed in a constant temperature shaker at 30 ℃ and 150 rpm for 20 hours to obtain the urease-producing bacterial suspension.

[0035] The soil used in this embodiment comes from near-surface residual soil of fully weathered and strongly weathered granite in the Xiyuan Palace area of ​​Fuzhou.

[0036] Example 1

[0037] 1. Preparation of repair filler and treatment of the area to be repaired

[0038] 1) Dissolve 240 g of urea and 444 g of anhydrous calcium chloride in water and bring the volume to 1 L to obtain a 4 mol / L cementing solution. Mix the urease-producing bacteria solution with the 4 mol / L cementing solution at a volume ratio of 4:1, and stir at 600 rpm for 12 hours. After stirring, place the mixture in a refrigerator at 4°C and let it stand for 6 hours. After standing, remove the supernatant to obtain the biological sludge. Figure 2 As shown.

[0039] 2) The biological mud, 4 mol / L cementing solution and soil that has been completely dried at 105 ℃ are mixed at a mass ratio of 1:1:8 and stirred evenly to obtain the repair filler. The moisture content of the obtained repair filler is 25%.

[0040] 3) Soak the freshly cut bamboo strips in a 10% salt solution for 2 days, air dry them, and then steam them in boiling water at 100℃ for 12 hours. The resulting bamboo strips will be used as a supporting frame.

[0041] 4) Construct a layered support framework in the area to be repaired and fill it with repair filler material, such as... Figure 3 As shown, the sample has a diameter of 61.8 mm and a height of 40 mm.

[0042] 5) Use the remaining repair filler to fill the gaps at the edges, ensuring that there are no cracks in the area to be repaired.

[0043] 2. Preparation of biological treatment solution and spraying of the area to be repaired.

[0044] 1) Mix raw soybean powder and tap water at a mass ratio of 1:10, using 100g / L of raw soybean powder. Stir for 30 minutes, then place the mixture in a refrigerator at 4℃ and let it stand for 12 hours. The upper suspension separated after standing is the soybean enzyme solution.

[0045] 2) such as Figure 4 As shown, a biological treatment solution was prepared by mixing soybean enzyme solution and 2 mol / L cementing solution at a volume ratio of 1:1. This solution was then sprayed evenly onto the repaired area after filling, with a single spray volume of 2 L / m². 2 A total of 7 spraying sessions were conducted, with each spraying session spaced 24 hours apart. The soil samples after treatment are shown below. Figure 5 As shown.

[0046] 3) Indoor disintegration tests were conducted on the treated soil samples. The soil samples were placed in water for 1 minute, 5 minutes, 10 minutes, 30 minutes, 1 hour, 2 hours, 4 hours, 6 hours, 12 hours, and 24 hours. The test results are as follows: Figure 6 , 7 As shown, the sample can maintain its original shape after being soaked in water for 24 hours, and the disintegration rate A of the sample is... t The disintegration rate is 0%. The formula for calculating the disintegration rate is: A t =(R0-R t ) / R0, where R 0 represents the initial mass of the sample. R t Let be the mass of the sample at time t. The test results demonstrate that the soil treated with mixing and spraying reinforcement exhibits good resistance to disintegration.

[0047] Simultaneously, direct shear tests were conducted on the samples. Four different normal stresses were set: 100 kPa, 200 kPa, 300 kPa, and 400 kPa. The shear rate was 0.8 mm / min, and the shear amount was 6 mm. According to the "Standard for Geotechnical Testing Methods GB / T50123-2019", under each normal stress, the shear stress corresponding to a shear amount of 4 mm was taken as the shear strength under that normal stress. The obtained shear strength values ​​were plotted on a graph and linearly fitted. The slope and intercept of the line represent the internal friction angle and cohesion, respectively. The test results are as follows: Figure 8 As shown, the strength of the soil treated using the method proposed in this invention is effectively improved. The cohesion of the sample reaches 62.65 kPa, and the internal friction angle is 27.03°.

[0048] Example 2

[0049] Repair filler was prepared using the same processing technology as in Example 1, and a layered support skeleton and repair filler were constructed.

[0050] A biotreatment solution was prepared by mixing soybean enzyme solution and 2 mol / L cementing solution at a volume ratio of 1:1. This solution was then sprayed evenly onto the repaired area after filling, with a single spray volume of 2 L / m². 2 The spraying was carried out three times, with a 24-hour interval between each spraying.

[0051] The treated samples were subjected to disintegration and direct shear tests, such as... Figure 6 As shown, the sample exhibited good anti-disintegration properties; after soaking in water for 24 hours, the disintegration rate was only 10%. The direct shear test results are as follows: Figure 9 As shown, the cohesive force of the sample is 54.7 kPa and the internal friction angle is 25.65°.

[0052] Example 3

[0053] Repair filler was prepared using the same processing technology as in Example 1, and a layered support skeleton and repair filler were constructed.

[0054] A biotreatment solution was prepared by mixing soybean enzyme solution and 2 mol / L cementing solution at a volume ratio of 1:1. This solution was then sprayed evenly onto the repaired area after filling, with a single spray volume of 2 L / m². 2 The system was sprayed a total of 5 times, with each spraying interval being 24 hours.

[0055] The treated samples were subjected to disintegration and direct shear tests, such as... Figure 6 As shown, the sample exhibited good anti-disintegration properties, with a disintegration rate of only 7.4% after immersion in water for 24 hours. The direct shear test results are as follows... Figure 10 As shown, the cohesive force of the sample is 61.4 kPa and the internal friction angle is 24.71°.

[0056] Comparative Example 1

[0057] A control test was conducted on untreated soil. The specific sample preparation steps are as follows:

[0058] 1) Mix completely dried soil with water at a mass ratio of 4:1. The moisture content of the mixed soil is 25%.

[0059] 2) The mixed soil was loaded into the ring sampler and compacted. The compaction degree of the sample was 95%.

[0060] Disintegration test results as follows Figure 6 As shown, the sample disintegration rate reached 100% (complete disintegration) within 10 minutes.

[0061] Comparative Example 2

[0062] Repair filler was prepared using the same processing technology as in Example 1, and a layered support framework was constructed before filling with the repair filler. A control experiment was conducted without using soybean enzyme solution for spray reinforcement.

[0063] Disintegration test results as follows Figure 6 As shown, the erosion resistance of the sample was improved to a certain extent, and the disintegration rate of the sample after immersion in water for 24 hours was 27.36%. The direct shear test results are as follows... Figure 11 As shown, the cohesive force of the sample is 50.25 kPa and the internal friction angle is 26.83°.

[0064] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for repairing earthen sites using biological mud, characterized in that, Includes the following steps: (1) Mix the urease-producing bacteria solution with the cementing solution and stir continuously. After standing, remove the supernatant to obtain biological mud. The volume ratio of urease-producing bacterial solution to cementing solution was 3:1 to 7:1, the concentration of cementing solution was 4.0 mol / L, the stirring time was 8 to 12 h, and the standing time was 4 to 6 h. (2) Prepare repair filler by mixing biological mud, cementing liquid and soil consistent with the soil body of the site to be repaired and stirring evenly. (3) Select bamboo strips that have been soaked in salt water and steamed at high temperature to construct a supporting framework in layers in the area to be repaired and fill it with repair filler. Use the remaining repair filler to fill the gaps at the edges. The bamboo strips are freshly cut bamboo pieces that have been soaked in a 5% to 10% salt water solution for 1 to 2 days, air-dried, and then steamed in boiling water at 100°C for 6 to 12 hours. The compaction degree of the repair filler shall not be less than 90%. (4) Mix soybean enzyme solution with cementing solution to prepare biological treatment solution, and spray the biological treatment solution on the repaired area and its surrounding surface multiple times for curing. The number of sprays is 3 to 7, and the time interval between each spray is 24 hours.

2. The method according to claim 1, characterized in that: The cementing solution is a mixture containing urea and CaCl2 at equimolar concentrations.

3. The method according to claim 1, characterized in that: In step (2), the mass ratio of cementing liquid, biological mud, and soil from the site to be repaired is 1:1:8~3:1:16; the concentration of the cementing liquid is 2.0~4.0 mol / L, and the moisture content of the repair filler is 25~30%.

4. The method according to claim 1, characterized in that: In step (4), the soybean enzyme solution and the gelling solution are mixed at a volume ratio of 1:1, and the concentration of the gelling solution is 2.0 mol / L.

5. The method according to claim 1, characterized in that: The soybean enzyme solution mentioned in step (4) is obtained by stirring raw soybean powder with water for 30 minutes, letting it stand at 4°C for 12-24 hours, and separating the upper suspension. The amount of raw soybean powder used is 80-100 g / L.

6. The method according to claim 1, characterized in that: In step (4), the spraying rate of the biological treatment solution is 2~2.5 L / m³. 2 / Second-rate.

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