Foundation vacuum reinforcement device and reinforcement method based on microbial urease

Abstract

The invention discloses a microorganism urease-based foundation vacuum reinforcement device and reinforcement method, belongs to the technical field of foundation reinforcement, and solves the problem that urease inhibitors and mineralization reaction byproducts are enriched in soil and cannot be discharged after existing microorganism-induced soil mineralization reinforcement. The device specifically comprises a model box, a sealing assembly, a vacuum pipe set and a grouting pipe set. One end of the vacuum tube group penetrates through the sealing assembly and extends into the model box, and the other end is connected with the vacuum pump; calcareous sand is filled in the model box; one end of the grouting pipe set penetrates through the sealing assembly and is embedded in the calcareous sand, the other end of the grouting pipe set is connected with a grouting pump, and the grouting pump is connected with a slurry tank through a slurry pipe. In the present invention; the grouting pipe group is buried in the calcareous sand, and a microbial urease solution can be injected into the deep layer of the calcareous sand, so that the deep layer of the calcareous sand can be effectively reinforced; and mineralization reaction by-products can be pumped out of the model box through the vacuum pump, so that the reinforced calcareous sand is more compact and non-toxic to the environment.

Description

Technical Field

[0001] The invention relates to the technical field of foundation reinforcement, and in particular to a foundation vacuum reinforcement device and reinforcement method based on microbial urease. Background Art

[0002] With the acceleration of modern urbanization, the scale and height of buildings are increasing, and the requirements for soil are getting higher and higher. As one of the bearing bases of construction projects, the stability of the foundation is directly related to the safety of the overall structure. However, factors such as soil quality differences, changing geological conditions, and frequent natural disasters have made the stability of the foundation face challenges. Therefore, studying how to effectively strengthen the foundation and improve its bearing capacity and stability has become one of the urgent problems to be solved in the field of civil engineering.

[0003] Traditional soil treatment technology improves soil bearing capacity and stability through a series of physical and chemical actions, such as vibration reinforcement, soil replacement, chemical grouting, etc. However, traditional soil treatment technology is often accompanied by a series of environmental problems while modifying the soil. First, a large amount of waste and pollutants may be generated during soil treatment, such as excavated soil, waste materials and chemical additives, which may pollute the soil and groundwater. Secondly, mechanical reinforcement methods such as vibration reinforcement are usually accompanied by the use of large-scale mechanical equipment, often accompanied by large soil disturbance, low construction efficiency, high energy consumption and other problems. Therefore, while solving foundation problems, traditional soil treatment technology also needs to pay attention to environmental protection and sustainable development. It is very important to seek a more environmentally friendly and low-carbon treatment method to reduce the adverse impact on the soil environment and achieve sustainable utilization and protection of land resources.

[0004] As one of the important components of biomineralization, microbial mineralization technology is widely used in geological storage, environmental remediation, cultural relics protection and other fields due to its low carbon, high efficiency, controllability and environmental compatibility. It provides a green and environmentally friendly way to reduce carbon emissions, improve engineering geotechnical stability and geological energy storage. However, as a kind of biological population action, microbial mineralization has a significantly different mineralization mechanism from chemical mineralization, and its application reliability strongly depends on the environment. For example, temperature, pH, etc., the scope of action is severely limited. In addition, mineralizing microorganisms are mostly aerobic microorganisms, which have slow metabolic reactions in deep soils and may even lyse and die, leading to eutrophication and insufficient reinforcement depth. There is also a survival competition between exogenous mineralizing microorganisms and indigenous microorganisms, which makes it difficult for microbial mineralization technology to achieve the expected effect in actual application. Furthermore, the size of microorganisms is usually 2-5μm, and extracellular polymers will be produced during the growth stage. It is easy to form aggregates during the grouting process, which is easy to block the grouting port, resulting in poor plugging effect of small pores, an increase in grouting pressure in the later stage, and an increase in grouting costs, which leads to uneven soil treatment in the gravity direction. In addition to the above problems, microbial mineralization reactions will generate ammonia as a by-product, which will cause secondary pollution to the soil if it is enriched in the soil for a long time.

[0005] A method for consolidating soil by stimulating the cultivation of in-situ microorganisms is disclosed in a Chinese invention patent with publication number CN111501733A. This method adds stimulating liquid to the soil to promote the reproduction of microorganisms in the soil, and then adds a cementing liquid to the soil to consolidate the soil; although it saves manpower and material resources to a certain extent, the uniformity of reinforcement depends entirely on the distribution of microorganisms in the soil, and mineralized microorganisms are only distributed in the shallow layer of the soil layer, and deep soil cannot be effectively reinforced.

[0006] A method for soil grouting with microbial induced mineralization reinforcement by introducing urease inhibitors is disclosed in the Chinese invention patent with authorization number CN111441337B. The method fully mixes the urease-producing bacterial solution with the soil to be solidified, and leaves it to stand until the urease-producing bacterial solution is attached to the particle surface of the soil to be solidified; then, the urease inhibitor is added to the cementing liquid, and grouting is performed after sufficient stirring and dissolution. Although the uniformity of the solidification effect is increased to a certain extent, it still cannot be treated for deep soil, and the urease inhibitor and mineralization reaction by-products are still abundant in the soil and cannot be effectively removed.

[0007] In summary, there is currently no effective solution on how to use microorganisms and their metabolites to reinforce deep soil, improve the uniformity of the reinforced body, avoid biological competition, and remove ammonia by-products. Summary of the invention

[0008] In view of the deficiencies in the prior art, the present invention provides a foundation vacuum reinforcement device and reinforcement method based on microbial urease, which solves the problem that urease inhibitors and mineralization reaction by-products are enriched in the soil and cannot be discharged after the existing microbial induced soil mineralization reinforcement.

[0009] In the first aspect, in order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is:

[0010] A foundation vacuum reinforcement device based on microbial urease comprises a model box, a sealing component, a vacuum tube group and a grouting tube group; a sealing component is arranged on the top of the model box, one end of the vacuum tube group passes through the sealing component and extends into the interior of the model box, the other end of the vacuum tube group is connected to a water-gas separation tank, and the water-gas separation tank is connected to a vacuum pump through an air pressure pipe; calcareous sand is filled in the model box; one end of the grouting tube group passes through the sealing component and is buried in the calcareous sand, the other end of the grouting tube group is connected to a grouting pump, and the grouting pump is connected to a slurry tank through a slurry pipe.

[0011] In this scheme, the microbial urease solution in the slurry tank can be injected into the model box through the grouting pipe group and penetrate into the tiny pores of the calcareous sand. The induced carbonate ions can react with the calcium salt to generate adhesive carbonate precipitates to solidify the calcareous sand and improve its strength; the end of the grouting pipe group is buried in the calcareous sand, and the microbial urease solution can be injected into the deep layer of the calcareous sand to avoid the microbial urease solution being distributed only in the shallow layer of the calcareous sand and failing to effectively reinforce the deep calcareous sand; one end of the vacuum pipe group is connected to the model box, and the other end is connected to the vacuum pump. The by-products of the mineralization reaction of the reinforced calcareous sand can be extracted from the model box through the vacuum pump, making the reinforced calcareous sand more compact and non-toxic to the environment.

[0012] Furthermore, the grouting pipe group includes a grouting main pipe and a plurality of grouting branch pipes, one end of the grouting main pipe is connected to a grouting pump, and the other end of the grouting main pipe is respectively connected to a plurality of grouting branch pipes; the plurality of grouting branch pipes are buried in the calcareous sand, and each grouting branch pipe is provided with a plurality of grouting holes;

[0013] A main grouting valve is provided on the main grouting pipe, and a branch grouting valve is provided on each grouting branch pipe.

[0014] In this solution, the grouting branch pipes are evenly buried in the calcareous sand, so that the microbial urease solution can be dispersed to every corner of the calcareous sand, ensuring the uniformity of the calcareous sand reinforcement.

[0015] Furthermore, the vacuum pipe group includes a plurality of vacuum branch pipes and a vacuum main pipe, one end of the plurality of vacuum branch pipes passes through the sealing assembly and extends into the interior of the model box, and the other ends of the plurality of vacuum branch pipes are connected to the grouting main pipe; one end of the vacuum main pipe is connected to the grouting main pipe, and the other end of the vacuum main pipe is connected to the water-gas separation tank;

[0016] A main vacuum valve is provided on the vacuum main pipe, and a branch vacuum valve is provided on each vacuum branch pipe.

[0017] In this scheme, the vacuum branch pipe extends into the interior of the model box but does not touch the calcareous sand. After the microbial urease solution is injected into the model box, negative pressure can be pumped into the model box through the vacuum branch pipe to accelerate the infiltration of the microbial urease solution in the calcareous sand and promote the uniformity of the distribution of the microbial urease solution in the vertical direction. One end of the vacuum main pipe is connected to the grouting main pipe. After the reinforcement is completed, the vacuum pump provides negative pressure, and the mineralization reaction by-products in the model box can be extracted from the model box through the grouting branch pipe and the vacuum main pipe in turn. This design uses the grouting branch pipe to simultaneously achieve the effect of injecting the microbial urease solution and extracting the reaction by-products, and the pipeline layout is simple.

[0018] Furthermore, a drain pipe is connected to the bottom of the water-gas separation tank, and a drain valve is provided on the drain pipe; a vacuum gauge is arranged on the top of the water-gas separation tank.

[0019] In this scheme, the vacuum pump draws the solidified microbial urease solution and the by-products of the mineralization reaction into the water-gas separation tank. When the solution inside the water-gas separation tank is almost full, it is discharged through the drain pipe.

[0020] In a second aspect, the present invention provides a foundation vacuum reinforcement method based on microbial urease based on the first aspect, comprising the following steps:

[0021] S1: preparing microbial urease solution and cementing solution;

[0022] S2: Filling the model box with calcareous sand using the sand rain method;

[0023] S3: inject deionized water into the model box to rinse the calcareous sand;

[0024] S4: injecting the microbial urease solution into the slurry tank, and starting the grouting pump to inject the microbial urease solution into the calcareous sand;

[0025] S5: Start the vacuum pump to pump the microbial urease solution in the calcareous sand into the water-gas separation tank;

[0026] S6: inject the cementing solution into the slurry tank, start the grouting pump to inject the cementing solution into the calcareous sand; the first reinforcement is completed;

[0027] S7: Repeat S4 to S6 to perform cyclic reinforcement on the calcareous sand in the model box.

[0028] In this scheme, before using microbial urease solution and cementing solution for reinforcement, deionized water is first injected into the calcareous sand for washing to prevent impurities in the calcareous sand from affecting the reinforcement effect; during reinforcement, the microbial urease solution is first injected into the pores of the calcareous sand through a grouting pump, and then pumped out through a vacuum pump; then the cementing solution is injected through the grouting method to allow the carbonate ions induced by the microorganisms to react with the calcium salts to form calcium carbonate precipitates, thereby improving the strength of the soil.

[0029] Furthermore, S1 includes:

[0030] S101: Determine the dosage of microbial urease solution and cementing solution;

[0031] According to the measured soil porosity, treatment area and treatment depth, the amount of microbial urease solution V required for single vacuum consolidation of calcareous sand is determined. B and the amount of cementing solution V C :

[0032] V B =AHnα

[0033] V C =AHnβ

[0034] Wherein, A is the treatment area of ​​the calcareous sand to be reinforced; H is the treatment depth of the calcareous sand to be reinforced; n is the porosity of the soil; α and β are the volume correction coefficients of the microbial urease solution and the cementing solution, respectively;

[0035] S102: preparing a mother bacteria liquid culture medium; dissolving yeast extract and ammonium chloride particles in deionized water, adding nickel chloride hexahydrate particles and stirring; adding deionized water to make up the volume, and then adjusting the pH value to 9.15 with sodium hydroxide solution to obtain a mother bacteria liquid culture medium;

[0036] S103: inoculation; inoculating the pasteurian spore Sarcina into the mother bacteria liquid culture medium at a volume ratio of 1:100, and placing the mother bacteria liquid culture medium in a constant temperature shaking box for culturing for 18 hours at a temperature of 35° C. and a rotation speed of 150 rpm / min to obtain a microbial mother solution;

[0037] S104: expansion culture; placing the mother bacteria liquid culture medium in a reactor, and then adding the microbial mother solution for culture; after the culture is completed, diluting with deionized water;

[0038] S105: extracting urease; after the bacteria in the microbial mother solution are precipitated, taking the supernatant and filtering it with a filter; storing the filtered microbial mother solution in a container at 4°C until the bottom is completely precipitated; diluting the bottom precipitate with deionized water, and then ultrasonically crushing the bottom precipitate to obtain a microbial crushing solution; filtering the microbial crushing solution to obtain a microbial urease solution;

[0039] S106: preparing a cementing solution; dissolving calcium salt and urea in deionized water, stirring and dissolving to obtain a cementing solution with a concentration of 1 M.

[0040] In this scheme, the amount of microbial urease solution and cementing solution in the vacuum reinforcement treatment is quantitatively calculated according to the amount of earthwork to be reinforced for calcareous sand. Under the premise of meeting the requirements of engineering use, the waste of reaction slurry is avoided, the economic cost is saved, and the feasibility of engineering application is improved. The microorganism used is Bacillus pasteurianus, which is a high-yield urease microorganism. It induces hydrolysis reaction of organic carbon source to provide carbonate ions, and the carbonate ions combine with calcium ions in calcium salts to form adhesive carbonate precipitates. The 1M cementing solution concentration can maximize the production of calcium carbonate without inhibiting urease activity. The selected Bacillus pasteurianus has the advantages of high yield, non-toxicity, easy cultivation and wide source.

[0041] Furthermore, S3 includes:

[0042] S301: Deionized water is added to the slurry tank, the main grouting valve and the branch grouting valve are opened, and the main vacuum valve and the branch vacuum valve are closed;

[0043] S302: Start the grouting pump to inject deionized water into the model box so that the deionized water level is above the calcareous sand; and let it stand for 24 hours;

[0044] S303: close the main grouting valve and the branch vacuum valve, and open the main vacuum valve and the branch grouting valve;

[0045] S304: Start the vacuum pump, which draws the deionized water inside the model box into the water-gas separation tank through the grouting branch pipe.

[0046] Furthermore, S4 includes:

[0047] S401: Add microbial urease solution into the slurry tank; open the main grouting valve and the branch grouting valve, and close the main vacuum valve and the branch vacuum valve;

[0048] S402: Start the grouting pump to inject the microbial urease solution into the calcareous sand;

[0049] S403: close the main grouting valve and the branch grouting valve, and open the main vacuum valve and the branch vacuum valve;

[0050] S404: starting the vacuum pump, which extracts the gas inside the model box through the vacuum branch pipe, so that the microbial urease solution can penetrate the calcareous sand faster;

[0051] S405: Maintain the negative pressure inside the model box for more than 0.5h.

[0052] In this scheme, after the microbial urease solution is injected into the calcareous sand, the vacuum pump can extract the air inside the model box through the vacuum branch pipe, so that the inside of the model box is in a negative pressure state, which can accelerate the infiltration of the microbial urease solution in the calcareous sand, allowing the microbial urease solution to penetrate into deeper pores and promote the uniformity of the slurry distribution in the vertical direction.

[0053] In the third aspect, the present invention provides a soil column vacuum reinforcement device based on microbial urease, which is used to reinforce soil columns; it specifically includes a model tube, which is fixed in a vacuum barrel; a drain pipe is provided at the bottom of the model tube, and a drain valve is provided on the drain pipe; the model tube is filled with sand; one end of a water injection pipe is provided at the barrel mouth of the model tube, and the other end of the water injection pipe passes through the vacuum barrel and is connected to a peristaltic pump, and the peristaltic pump is connected to a storage container through a slurry pipe; the vacuum barrel is connected to the negative pressure pump through a negative pressure pipe; an air valve is provided on the negative pressure pipe, and a water stop valve is provided on the water injection pipe.

[0054] In this solution, a drainage pipe is arranged at the bottom of the model tube, and the microbial urease solution and mineralization reaction by-products used for reinforcing the sand can be discharged from the model tube through the drainage pipe, so that the reinforced sand is more compact.

[0055] In a fourth aspect, the present invention provides a soil column vacuum reinforcement method based on microbial urease based on the soil column vacuum reinforcement device provided in the third aspect, comprising the following steps:

[0056] T1: preparation of microbial urease solution and cementing solution;

[0057] T2: Fill the inside of the model tube with sand;

[0058] T3: inject the microbial urease solution into the storage container, start the peristaltic pump to inject the microbial urease solution into the model cylinder through the water injection pipe;

[0059] T4: Start the negative pressure pump to extract the gas inside the vacuum barrel through the negative pressure pipe to accelerate the penetration of the microbial urease solution into the sand in the model barrel;

[0060] T5: Open the drain valve to discharge the microbial urease solution in the model cylinder through the drain pipe;

[0061] T6: inject the cementing solution into the storage container, start the peristaltic pump to inject the cementing solution into the model cylinder through the water injection pipe;

[0062] T7: Start the negative pressure pump to extract the gas inside the vacuum barrel through the negative pressure pipe to accelerate the infiltration of the cementing solution into the sand in the model cylinder; maintain the negative pressure for more than 3.5 hours, and the first reinforcement is completed;

[0063] T8: Repeat T3 to T7 to cyclically reinforce the sand in the model tube.

[0064] The beneficial effects of the present invention are:

[0065] The vacuum reinforcement device for foundation based on microbial urease provided by the present invention can more evenly penetrate into the calcareous sand than the traditional MICP repair technology, and a vacuum pump is used to provide negative pressure during the reinforcement to ensure that the microbial urease solution can quickly penetrate into the deep layer of the calcareous sand, and can generate rhombic calcite crystal clusters with high hardness, stable structure and certain arrangement direction on the surface and pores of the calcareous sand particles, which can repair extremely small pores, and its reinforcement limit is much lower than the limit of ultrafine cement reinforcement pores; the reinforced soil has uniform texture and high density. Urease is a protein molecule that can work under anaerobic conditions, can effectively avoid the loss of reinforcement strength caused by bacterial inactivation under the condition of low oxygen content in the deep soil, can avoid the reduction of microbial activity caused by biological competition with indigenous microorganisms, and has outstanding advantages such as large reinforcement depth, good reinforcement uniformity, and wide environmental applicable conditions, and has significantly improved the mechanical properties and impermeability of geotechnical materials such as coral sand, bank slope soil, and calcareous sand under different engineering geological conditions.

[0066] In the vacuum reinforcement method for foundation based on microbial urease provided by the present invention, bacteria are crushed when preparing the microbial urease solution, and then the cell fragments, large impurities and other particles after the bacteria are crushed are effectively removed through the filter membrane, which can protect the subsequent grouting equipment and improve the purity of urease; the higher urease concentration promotes the reaction and accelerates the rapid formation of unstable crystals. After the microbial urease solution is injected, the air inside the model box is extracted by a vacuum pump. Under the drive of vacuum, the microbial urease solution can migrate a deeper distance, thereby improving the uniformity of the distribution of the microbial urease solution. The microbial urease solution under low temperature refrigeration can maintain high activity for a long time, providing a guarantee for large-scale grouting. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 This is a schematic diagram of the structure of a foundation vacuum reinforcement device based on microbial urease according to the present invention;

[0068] Figure 2 for Figure 1 A partial enlarged view of the middle A area;

[0069] Figure 3 This is a physical picture of the standard compression specimen in Example 2 of the present invention;

[0070] Figure 4 This is a schematic structural diagram of a soil column vacuum reinforcement device based on microbial urease according to the present invention;

[0071] Figure 5 This is a physical picture of the reinforced soil column in Example 4 of the present invention.

[0072] Reference numerals:

[0073] 1. Model box; 2. Sealing assembly; 21. Woven cloth; 22. Geotextile; 23. Sealing film; 3. Vacuum tube group; 31. Vacuum branch pipe; 32. Vacuum main pipe; 33. Main vacuum valve; 34. Branch vacuum valve; 4. Grouting pipe group; 41. Grouting branch pipe; 42. Grouting main pipe; 43. Main grouting valve; 44. Branch grouting valve; 5. Water-gas separation tank; 51. Drain valve; 52. Vacuum gauge; 6. Vacuum pump; 7. Grouting pump; 8. Slurry tank; 10. Model tube; 101. Drain valve; 102. Support frame; 11. Vacuum barrel; 12. Water injection pipe; 13. Peristaltic pump; 14. Storage container; 15. Negative pressure tube; 16. Negative pressure pump; 17. Air valve; 18. Water stop valve; 19. Air pressure gauge; 20. Collection tube; DETAILED DESCRIPTION

[0074] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. The specific implementation of the present invention is described below to facilitate the understanding of the present invention by those skilled in the art, but it should be clear that the present invention is not limited to the scope of the specific implementation. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention defined and determined by the attached claims, these changes are obvious, and all inventions and creations using the concept of the present invention are protected.

[0075] Example 1

[0076] like Figure 1 As shown, this embodiment provides a foundation vacuum reinforcement device based on microbial urease, which can make the microbial urease solution and the cementing solution more evenly penetrate into the deep layer of calcareous sand, and the reinforced soil has uniform texture and high density; it can also discharge the reinforced urease inhibitor and mineralization reaction by-products; it specifically includes:

[0077] Model box 1, sealing assembly 2, vacuum pipe group 3 and grouting pipe group 4;

[0078] Among them, a sealing component 2 is provided on the top of the model box 1, one end of the vacuum tube group 3 passes through the sealing component 2 and extends into the interior of the model box 1, and the other end of the vacuum tube group 3 is connected to the water-gas separation tank 5, and the water-gas separation tank 5 is connected to the vacuum pump 6 through an air pressure tube; the model box 1 is filled with calcareous sand; one end of the grouting pipe group 4 passes through the sealing component 2 and is buried in the calcareous sand, and the other end of the grouting pipe group 4 is connected to a grouting pump 7, and the grouting pump 7 is connected to a slurry tank 8 through a slurry pipe; the microbial urease solution in the slurry tank 8 can be injected into the model box 1 through the grouting pipe group 4, and penetrate into the tiny pores of the calcareous sand, and the induced carbonate ions can react with the calcium salt to generate adhesive carbonate precipitates to solidify the calcareous sand and improve its strength.

[0079] The grouting pipe group 4 includes a grouting main pipe 42 and a plurality of grouting branch pipes 41. One end of the grouting main pipe 42 is connected to the grouting pump 7, and the other end of the grouting main pipe 42 is respectively connected to the plurality of grouting branch pipes 41; the plurality of grouting branch pipes 41 are all buried in the calcareous sand; there are two rows of grouting branch pipes 41, each row has five grouting branch pipes 41, and two adjacent ones are arranged at an interval of 50 cm. The grouting branch pipes 41 close to the boundary are spaced 25 cm from the wall, and each grouting pipe is punched with 13 grouting holes; this layout allows the microbial urease solution to be evenly dispersed to every corner of the calcareous sand through the grouting holes, thereby ensuring the uniformity of the calcareous sand reinforcement; a main grouting valve 43 is provided on the grouting main pipe 42, and a branch grouting valve 44 is provided on each grouting branch pipe 41.

[0080] The vacuum pipe group 3 includes a plurality of vacuum branch pipes 31 and a vacuum main pipe 32. One end of the plurality of vacuum branch pipes 31 passes through the sealing assembly 2 and extends into the interior of the model box 1, and the other ends of the plurality of vacuum branch pipes 31 are connected to the grouting main pipe 42; one end of the vacuum main pipe 32 is connected to the grouting main pipe 42, and the other end of the vacuum main pipe 32 is connected to the water-gas separation tank 5; the vacuum branch pipe 31 extends into the interior of the model box 1 but does not touch the calcareous sand. After the microbial urease solution is injected into the model box 1, negative pressure can be drawn into the model box 1 through the vacuum branch pipe 31 to accelerate the infiltration of the microbial urease solution in the calcareous sand and promote the uniformity of the distribution of the microbial urease solution in the vertical direction; a main vacuum valve 33 is provided on the vacuum main pipe 32, and a branch vacuum valve 34 is provided on each vacuum branch pipe 31.

[0081] A drain pipe is connected to the bottom of the water-gas separation tank 5, and a drain valve 51 is provided on the drain pipe; a vacuum gauge 52 is arranged on the top of the water-gas separation tank 5; a vacuum pump 6 draws the solidified microbial urease solution and the by-products of the mineralization reaction into the water-gas separation tank 5, and when the solution inside the water-gas separation tank 5 is almost full, it is discharged through the drain pipe.

[0082] like Figure 2 As shown, the sealing assembly 2 includes a sealing film 23, a geotextile 22 and a woven fabric 21; the sealing film 23 can be fixed to the top of the model box 1 by gluing, and the geotextile 22 and the woven fabric 21 cover the top of the sealing film 23 in sequence.

[0083] Example 2

[0084] This embodiment is based on a foundation vacuum reinforcement device based on microbial urease provided in Example 1, and provides a foundation vacuum reinforcement method based on microbial urease, comprising the following steps:

[0085] S1: preparing microbial urease solution and cementing solution; specifically comprising:

[0086] S101: Determine the dosage of microbial urease solution and cementing solution;

[0087] According to the measured soil porosity, treatment area and treatment depth, the amount of microbial urease solution V required for single vacuum consolidation of calcareous sand is determined. B and the amount of cementing solution V C :

[0088] V B =AHnα

[0089] V C =AHnβ

[0090] Wherein, A is the treatment area of ​​the calcareous sand to be reinforced; H is the treatment depth of the calcareous sand to be reinforced; n is the porosity of the soil; α and β are the volume correction coefficient of the microbial urease solution and the volume correction coefficient of the cementing solution, respectively; the value range of α and β is 1.05-1.55;

[0091] In this embodiment, the length, width and height of the model box 1 are 2m, 0.8m and 1m respectively; therefore, the treatment area A of the calcareous sand to be reinforced is length*width equal to 1.6m 2 The treatment depth H of the calcareous sand to be reinforced is 1m; the minimum dry density and maximum dry density of the calcareous sand are 1279.2kg / m 3 and 1588kg / m 3 , specific gravity is 2.811, porosity is 51.53%;

[0092] The volume correction coefficient α of the microbial urease solution and the volume β of the cementing solution were both set to 1.05. The calculated single dosage of the microbial urease solution and the cementing solution was 0.87 m 3 .

[0093] S102: preparing a mother bacteria liquid culture medium; dissolving 20 g of yeast extract and 10 g of ammonium chloride particles in deionized water, and then adding 24 mg of nickel chloride hexahydrate particles and stirring; adding deionized water to make the volume 1 L, and then adjusting the pH value to 9.15 with a 1 mol / L sodium hydroxide solution to obtain a mother bacteria liquid culture medium; bottling the mother bacteria culture medium, each bottle is 1 L, and a total of 100 bottles are filled;

[0094] Liquid culture medium for expanding mother bacteria: The liquid culture medium for expanding bacteria is the amount of microbial urease solution determined in step S101 minus the amount of liquid culture medium for mother bacteria, a total of 0.77 m 3 .

[0095] S103: inoculation; inoculating the pasteurian spore Sarcina into the mother bacteria liquid culture medium at a volume ratio of 1:100, and placing the mother bacteria liquid culture medium in a constant temperature shaking box for culturing for 18 hours at a temperature of 35° C. and a rotation speed of 150 rpm / min to obtain a microbial mother solution;

[0096] S104: Expansion culture: placing the mother bacteria liquid culture medium in the reactor, placing 70L each time, and then adding the microbial mother solution for cultivation, adding 10 bottles each time, a total of 80L of bacterial liquid each time; after the cultivation is completed, dilute with deionized water to 90L;

[0097] S105: extracting urease; after the bacteria in the microbial mother solution are precipitated, taking the supernatant and filtering it with a filter; the filtered microbial mother solution is placed in a container and stored at 4°C until the bottom is completely precipitated; the bottom precipitate is diluted with deionized water, and the specific amount of deionized water used depends on the actual precipitate content; the bottom precipitate is then ultrasonically crushed to obtain a microbial crushing solution; then, a qualitative filter paper is used to perform a coarse filtration for 3 times, and then a filter is used to finely filter the coarse filtered solution, and all the stored solutions are mixed with the solution to obtain a microbial urease solution, and the urease activity therein is measured;

[0098] S106: preparing a cementing solution; dissolving calcium salt and urea in deionized water at a mass ratio of 111:60.06, stirring and dissolving to obtain a cementing solution with a concentration of 1M; wherein the calcium salt may be calcium chloride, and the required mass of calcium chloride is 96.57kg, and the mass of urea is 52.25kg.

[0099] In this embodiment, the amount of microbial urease solution and cementing solution in the vacuum reinforcement treatment is quantitatively calculated according to the amount of earthwork to be reinforced for calcareous sand. Under the premise of meeting the requirements for engineering use, the waste of reaction slurry is avoided, the economic cost is saved, and the feasibility of engineering application is improved. The microorganism used is Bacillus pasteurianus, which is a high-yield urease microorganism. It induces hydrolysis reaction of organic carbon source to provide carbonate ions, and the carbonate ions combine with calcium ions in calcium salts to form adhesive carbonate precipitates. The 1M cementing solution concentration can maximize the generation of calcium carbonate without inhibiting urease activity. The microorganism can be Bacillus pasteurianus or Bacillus pasteurianus, preferably Bacillus pasteurianus. The selected Bacillus pasteurianus has the advantages of high yield, non-toxicity, easy cultivation and wide source.

[0100] S2: Filling the model box 1 with calcareous sand by using the sand rain method; the specific operation is as follows:

[0101] The calcareous sand is loaded into the model tank in batches, and the density of the calcareous sand at each position in the model box 1 is kept the same as much as possible. The mass of the calcareous sand loaded each time is between 100-110 kg, and the loading is completed in 23 times. At the beginning of loading, the grouting branch pipe 41 needs to be fixed at a preset position in the model box 1 by hand. When the calcareous sand reaches a certain thickness, the grouting branch pipe 41 can remain vertical under the action of the calcareous sand without external human force, but it is still necessary to prevent the grouting branch pipe 41 from displacement during the entire loading process.

[0102] S3: injecting deionized water into the model box 1 to wash the calcareous sand; specifically including:

[0103] S301: Deionized water is added into the slurry tank 8, the main grouting valve 43 and the branch grouting valve 44 are opened, and the main vacuum valve 33 and the branch vacuum valve 34 are closed;

[0104] S302; start the grouting pump 7 to inject deionized water into the model box 1, so that the deionized water level is above the calcareous sand, and let it stand for 24 hours, wherein the grouting pressure is selected to be 0.02MPa; inject deionized water to wash the calcareous sand to prevent impurities in the calcareous sand from affecting the reinforcement effect;

[0105] S303: close the main grouting valve 43 and the branch vacuum valve 34, and open the main vacuum valve 33 and the branch grouting valve 44;

[0106] S304: starting the vacuum pump 6, which draws the deionized water inside the model box 1 into the water-gas separation tank 5 through the grouting branch pipe 41;

[0107] When the deionized water is about to fill up the water-gas separation tank 5, the vacuum pump 6 and the main vacuum valve 33 are closed, and the drain valve 51 is opened to discharge the deionized water in the water-gas separation tank 5 through the drain pipe.

[0108] S4: injecting the microbial urease solution into the slurry tank 8, and starting the grouting pump 7 to inject the microbial urease solution into the calcareous sand; specifically comprising:

[0109] S401: Add microbial urease solution into the slurry tank 8; open the main grouting valve 43 and the branch grouting valve 44, and close the main vacuum valve 33 and the branch vacuum valve 34;

[0110] S402: Start the grouting pump 7 to inject the microbial urease solution into the calcareous sand, and the grouting pressure is selected to be 0.02 MPa;

[0111] S403: close the main grouting valve 43 and the branch grouting valve 44, and open the main vacuum valve 33 and the branch vacuum valve 34;

[0112] S404: starting the vacuum pump 6, which extracts the gas inside the model box 1 through the vacuum branch pipe 31, so that the microbial urease solution can penetrate into the calcareous sand faster, ensuring that the microbial urease solution penetrates deeper into the pores, and promoting the uniformity of the slurry distribution in the vertical direction;

[0113] S405: Maintain the negative pressure inside the model box 1 for more than 0.5h.

[0114] S5: Start the vacuum pump 6 to pump the microbial urease solution in the calcareous sand into the water-gas separation tank 5; the specific operation is as follows;

[0115] Close the main grouting valve 43 and the branch vacuum valve 34, and open the main vacuum valve 33 and the branch grouting valve 44; start the vacuum pump 6, and the vacuum pump 6 draws the microbial urease solution inside the model box 1 into the water-gas separation tank 5 through the grouting branch pipe 41.

[0116] S6: injecting the cementing solution into the slurry tank 8, and starting the grouting pump 7 to inject the cementing solution into the calcareous sand; specifically comprising:

[0117] S601: Add cementing solution into the slurry tank 8; open the main grouting valve 43 and the branch grouting valve 44, and close the main vacuum valve 33 and the branch vacuum valve 34;

[0118] S602: Start the grouting pump 7 to inject the cementing solution into the calcareous sand, and the grouting pressure is selected to be 0.02 MPa;

[0119] S603: close the main grouting valve 43 and the branch grouting valve 44, and open the main vacuum valve 33 and the branch vacuum valve 34;

[0120] S604: starting the vacuum pump 6, which extracts the gas inside the model box 1 through the vacuum branch pipe 31, so that the cementing solution can penetrate faster inside the calcareous sand;

[0121] S605: Maintain the negative pressure inside the model box 1 for 20 hours; the first reinforcement is completed.

[0122] S7: Repeat S4 to S6 to perform cyclic reinforcement on the calcareous sand in the model box 1, for a total of 12 cyclic reinforcements; after the last cyclic reinforcement, enter S8.

[0123] S8: extract all the mixed liquid in the calcareous sand from the model box 1 and let it stand for 48 hours; after standing, remove the model box 1 to obtain a reinforced calcareous sand body; and allow the surface of the reinforced calcareous sand body to dry naturally.

[0124] S9: Take 4 pieces of reinforced calcareous sand every 13 cm in the vertical direction, dry them at 60℃ and make them into 150*150*150mm 3 Standard compression specimens, such as Figure 3 As shown; the unconfined compressive strength and permeability of standard compression specimens and the presence of ammonia nitrogen odor are determined.

[0125] Experimental results: The specimen had no obvious odor, and the bottom soil reinforcement effect was good. The differences in permeability and strength along the vertical direction were significantly reduced, and the uniformity was enhanced.

[0126] Example 3

[0127] This embodiment provides a soil column vacuum reinforcement device based on microbial urease, which is used to reinforce the soil column; the device specifically comprises: a model tube 10, a vacuum barrel 11, a water injection pipe 12, a peristaltic pump 13, a storage container 14, a negative pressure pipe 15 and a negative pressure pump 16;

[0128] Among them, a support frame 102 is provided at the bottom of the model tube 10, and the model tube 10 is suspended and fixed in the collection tube 20 through the support frame 102. The collection tube 20 is arranged in the vacuum barrel 11; a drain pipe is provided at the bottom of the model tube 10, and a drain valve 101 is provided on the drain pipe.

[0129] The model tube 10 is filled with sand; one end of a water injection pipe 12 is provided at the tube mouth of the model tube 10, and the other end of the water injection pipe 12 passes through the vacuum barrel 11 and is connected to a peristaltic pump 13, and the peristaltic pump 13 is connected to a storage container 14 through a slurry pipe.

[0130] The vacuum barrel 11 is connected to a negative pressure pump 16 via a negative pressure pipe 15 ; an air valve 17 is provided on the negative pressure pipe 15 , and a water stop valve 18 is provided on the water injection pipe 12 .

[0131] The model tube 10 is also provided with a barometer 19 .

[0132] The water injection pipe 12 can be a polytetrafluoroethylene tube with a glass tube connected to the end, and one end connected to the glass tube extends into the model tube 10; the glass tube is hard and heavy, and extending into the model tube 10 can prevent it from popping out during the grouting process.

[0133] Example 4

[0134] like Figure 4 As shown, this embodiment provides a soil column vacuum reinforcement method based on microbial urease based on a soil column vacuum reinforcement device provided in Example 3, and includes the following steps:

[0135] T1: Preparation of microbial urease solution and cementing solution; specifically including:

[0136] T101: Prepare a liquid culture medium; dissolve 20 g of yeast extract and 10 g of ammonium chloride particles in deionized water, add 24 mg of nickel chloride hexahydrate particles, stir well, and adjust the volume to 1 L, then adjust the pH value to 9.15 with 1 mol / L sodium hydroxide solution to obtain a liquid culture medium;

[0137] T102: inoculation; inoculate the pasteurian spore Sarcina into the liquid culture medium at a volume ratio of 1:100, and culture in a constant temperature shaking box for 18 hours at a temperature of 35°C and a rotation speed of 150 rpm / min to obtain a microbial culture liquid;

[0138] T103: Extract microbial urease; crush the microbial bacterial solution with ultrasonic oscillation, the oscillation power is 20%, the continuous oscillation time is 10s, the oscillation interval is 10s, and the total oscillation time is 20min; filter with a 0.22μm filter membrane to obtain a microbial urease solution and store it at 4℃; determine the urease activity in the microbial urease solution, and the recorded value is 21.11U;

[0139] T104: Prepare a cementing solution; add 111 g of calcium chloride granules and 60.06 g of urea granules into 1 L of deionized water and stir to dissolve to prepare a cementing solution with a concentration of 1 M.

[0140] T2: Filling the model tube 10 with sand; specifically including:

[0141] T201: The particle size distribution of the soil was measured. The uniformity coefficient (Cu) and curvature coefficient (Cc) were 1.31 and 1.01 respectively. Fine sand with a particle size of 0.15-0.25 mm was obtained by screening. The initial porosity of the sand filling was calculated to be 42.53%; the initial porosity, maximum dry density and minimum dry density of the sand were 0.74 and 1.6 g / cm respectively. 3 and 1.37 g / cm 3 ;

[0142] T202: Filling with sand; laying a film with a thickness of 0.1 mm on the bottom of the model tube 10 to facilitate the extraction of samples in the model tube 10 after reinforcement; then pad a layer of leak-proof cloth on the bottom of the model tube 10 to prevent the loss of sand particles, and then fill sand on the top of the leak-proof cloth; the sand is divided into four layers, each layer is about 2 cm high, and the total height of the sand is 8 cm; after the filling is completed, place another layer of leak-proof cloth on the top layer of sand; the leak-proof cloth is preferably a scouring pad, filter paper or filter cloth.

[0143] T3: Inject the microbial urease solution into the storage container 14 and open the water stop valve 18; start the peristaltic pump 13, and the peristaltic pump 13 injects the microbial urease solution in the storage container 14 into the model cylinder 10 through the water injection pipe 12 until the injection volume reaches 1.5PV, and then close the peristaltic pump 13 and the water stop valve 18.

[0144] T4: Open the air valve 17 and start the negative pressure pump 16. The negative pressure pump 16 draws out the gas inside the vacuum barrel 11 through the negative pressure pipe 15 to accelerate the penetration of the microbial urease solution into the sand in the model tube 10. When no more bubbles are generated in the microbial urease solution, close the air valve 17 and maintain the negative pressure for 0.5 hours.

[0145] T5: Open the drain valve 101 to discharge the microbial urease solution in the model cylinder 10 through the drain pipe; the discharged microbial urease solution is collected in the collection cylinder 20 to avoid waste.

[0146] T6: Inject the cementing solution into the storage container 14 and open the water stop valve 18; start the peristaltic pump 13 to inject the cementing solution into the model cylinder 10 through the water injection pipe 12 until the injection volume reaches 1.5PV, and close the peristaltic pump 13 and the water stop valve 18.

[0147] T7: Open the air valve 17 and start the negative pressure pump 16. The negative pressure pump 16 draws out the gas inside the vacuum barrel 11 through the negative pressure pipe 15 to accelerate the infiltration of the cementing solution into the sand in the model tube 10. Maintain the negative pressure for more than 3.5 hours, and the first reinforcement is completed.

[0148] T8: Repeat T3 to T7 to reinforce the sand in the model tube 10 12 times; after the last reinforcement, take out the reinforced soil column from the model tube 10 and enter T9. Figure 5 shown.

[0149] T9: Determine the unconfined compressive strength and the mass loss rate after 15 dry-wet cycles.

[0150] In this embodiment, after vacuum reinforcement treatment based on microbial urease, the unconfined compressive strength of the soil is increased by 260% compared with the normal MICP treated soil strength, and the mass loss rate after dry-wet cycles is attenuated to 10% of the MICP treated sample.

[0151] Those skilled in the art will appreciate that the embodiments herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the invention.

Claims

1. A vacuum foundation reinforcement device based on microbial urease, characterized in that: The invention comprises a model box (1), a sealing component (2), a vacuum tube group (3) and a grouting tube group (4); the top of the model box (1) is provided with a sealing component (2); one end of the vacuum tube group (3) passes through the sealing component (2) and extends into the interior of the model box (1); the other end of the vacuum tube group (3) is connected to a water-gas separation tank (5); the water-gas separation tank (5) is connected to a vacuum pump (6) via an air pressure pipe; the model box (1) is filled with calcareous sand; one end of the grouting tube group (4) passes through the sealing component (2) and is buried in the calcareous sand; the other end of the grouting tube group (4) is connected to a grouting pump (7); the grouting pump (7) is connected to a slurry tank (8) via a slurry pipe.

2. The vacuum reinforcement device for foundation based on microbial urease according to claim 1 is characterized in that: The grouting pipe group (4) comprises a grouting main pipe (42) and a plurality of grouting branch pipes (41); one end of the grouting main pipe (42) is connected to the grouting pump (7), and the other end of the grouting main pipe (42) is respectively connected to the plurality of grouting branch pipes (41); the plurality of grouting branch pipes (41) are all buried in the calcareous sand, and each of the grouting branch pipes (41) is provided with a plurality of grouting holes; The main grouting pipe (42) is provided with a main grouting valve (43), and each of the grouting branch pipes (41) is provided with a branch grouting valve (44).

3. The vacuum reinforcement device for foundation based on microbial urease according to claim 2 is characterized in that: The vacuum pipe group (3) comprises a plurality of vacuum branch pipes (31) and a vacuum main pipe (32); one end of the plurality of vacuum branch pipes (31) passes through the sealing assembly (2) and extends into the interior of the model box (1); the other ends of the plurality of vacuum branch pipes (31) are connected to the grouting main pipe (42); one end of the vacuum main pipe (32) is connected to the grouting main pipe (42), and the other end of the vacuum main pipe (32) is connected to the water-gas separation tank (5); The vacuum main pipe (32) is provided with a main vacuum valve (33), and each of the vacuum branch pipes (31) is provided with a branch vacuum valve (34).

4. The vacuum reinforcement device for foundation based on microbial urease according to claim 3 is characterized in that: The bottom of the water-gas separation tank (5) is connected to a drain pipe, and a drain valve (51) is provided on the drain pipe; and a vacuum gauge (52) is provided on the top of the water-gas separation tank (5).

5. A reinforcement method for a foundation vacuum reinforcement device based on microbial urease according to claim 4, characterized in that: The following steps are involved: S1: preparing microbial urease solution and cementing solution; S2: Filling the model box (1) with calcareous sand using the sand rain method; S3: injecting deionized water into the model box (1) to wash the calcareous sand; S4: injecting the microbial urease solution into the slurry tank (8), and starting the grouting pump (7) to inject the microbial urease solution into the calcareous sand; S5: starting the vacuum pump (6) to pump the microbial urease solution in the calcareous sand into the water-gas separation tank (5); S6: injecting the cementing solution into the slurry tank (8), starting the grouting pump (7) to inject the cementing solution into the calcareous sand; the first reinforcement is completed; S7: Repeat S4 to S6 to perform cyclic reinforcement on the calcareous sand in the model box (1).

6. The reinforcement method of the foundation vacuum reinforcement device based on microbial urease according to claim 5, characterized in that: The S1 includes: S101: Determine the dosage of microbial urease solution and cementing solution; According to the measured soil porosity, treatment area and treatment depth, the amount of microbial urease solution V required for single vacuum consolidation of calcareous sand is determined. B and the amount of cementing solution V C : V B =AHnα V C =AHnβ Wherein, A is the treatment area of ​​the calcareous sand to be reinforced; H is the treatment depth of the calcareous sand to be reinforced; n is the porosity of the soil; α and β are the volume correction coefficients of the microbial urease solution and the cementing solution, respectively; S102: preparing a mother bacteria liquid culture medium; dissolving yeast extract and ammonium chloride particles in deionized water, adding nickel chloride hexahydrate particles and stirring; adding deionized water to make up the volume, and then adjusting the pH value to 9.15 with sodium hydroxide solution to obtain a mother bacteria liquid culture medium; S103: inoculation; inoculating the pasteurian spore Sarcina into the mother bacteria liquid culture medium at a volume ratio of 1:100, and placing the mother bacteria liquid culture medium in a constant temperature shaking box for 18 hours at a temperature of 35°C and a rotation speed of 150 rpm / min to obtain a microbial mother solution; S104: expansion culture; placing the mother bacteria liquid culture medium in a reactor, and then adding the microbial mother solution for culture; after the culture is completed, diluting with deionized water; S105: extracting urease; after the bacteria in the microbial mother solution are precipitated, taking the supernatant and filtering it with a filter; storing the filtered microbial mother solution in a container at 4°C until the bottom is completely precipitated; diluting the bottom precipitate with deionized water, and then ultrasonically crushing the bottom precipitate to obtain a microbial crushing solution; filtering the microbial crushing solution to obtain a microbial urease solution; S106: preparing a cementing solution; dissolving calcium salt and urea in deionized water, stirring and dissolving to obtain a cementing solution with a concentration of 1 M.

7. The reinforcement method of the foundation vacuum reinforcement device based on microbial urease according to claim 6, characterized in that: The S3 includes: S301: Deionized water is added to the slurry tank (8), the main grouting valve (43) and the branch grouting valve (44) are opened, and the main vacuum valve (33) and the branch vacuum valve (34) are closed; S302; start the grouting pump (7) to inject deionized water into the model box (1) so that the deionized water level is above the calcareous sand; and let it stand for 24 hours; S303: closing the main grouting valve (43) and the branch vacuum valve (34), and opening the main vacuum valve (33) and the branch grouting valve (44); S304: Start the vacuum pump (6), and the vacuum pump (6) draws the deionized water inside the model box into the water-gas separation tank (5) through the grouting branch pipe (41).

8. The reinforcement method of the foundation vacuum reinforcement device based on microbial urease according to claim 7, characterized in that: The S4 includes: S401: Adding microbial urease solution into the slurry tank (8); opening the main grouting valve (43) and the branch grouting valve (44), and closing the main vacuum valve (33) and the branch vacuum valve (34); S402: starting the grouting pump (7) to inject the microbial urease solution into the calcareous sand; S403: close the main grouting valve (43) and the branch grouting valve (44), and open the main vacuum valve (33) and the branch vacuum valve (34); S404: starting the vacuum pump (6), the vacuum pump (6) extracts the gas inside the model box through the vacuum branch pipe (31), so that the microbial urease solution can infiltrate the calcareous sand faster; S405: Maintain the negative pressure inside the model box for more than 0.5h.

9. A soil column vacuum reinforcement device based on microbial urease, characterized in that: The invention comprises a model tube (10), wherein the model tube (10) is fixed in a vacuum barrel (11); a drainage pipe is provided at the bottom of the model tube (10), and a drainage valve (101) is provided on the drainage pipe; the model tube (10) is filled with sand; one end of a water injection pipe (12) is provided at the tube mouth of the model tube (10), and the other end of the water injection pipe (12) passes through the vacuum barrel (11) and is connected to a peristaltic pump (13); the peristaltic pump (13) is connected to a storage container (14) through a slurry pipe; the vacuum barrel (11) is connected to a negative pressure pump (16) through a negative pressure pipe (15); The negative pressure pipe (15) is provided with an air valve (17), and the water injection pipe (12) is provided with a water stop valve (18).

10. A method for reinforcing a soil column vacuum reinforcement device based on microbial urease according to claim 9, characterized in that: The following steps are involved: T1: preparation of microbial urease solution and cementing solution; T2: Filling the model tube (10) with sand; T3: injecting the microbial urease solution into the storage container (14), starting the peristaltic pump (13) to inject the microbial urease solution into the model cylinder (10) through the water injection pipe (12); T4: starting the negative pressure pump (16) to extract the gas inside the vacuum barrel (11) through the negative pressure pipe (15) to accelerate the penetration of the microbial urease solution into the sand in the model cylinder (10); T5: opening the drain valve (101) to discharge the microbial urease solution in the model cylinder (10) through the drain pipe; T6: injecting the cementing solution into the storage container (14), starting the peristaltic pump (13) to inject the cementing solution into the model cylinder (10) through the water injection pipe (12); T7: Start the negative pressure pump (16) to extract the gas inside the vacuum barrel (11) through the negative pressure pipe (15) to accelerate the infiltration of the cementing solution into the sand in the model tube (10); maintain the negative pressure for more than 3.5 hours, and the first reinforcement is completed; T8: Repeat T3 to T7 to perform cyclic reinforcement on the sand in the model tube (10).

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