A ground reinforcement solution, its preparation method and use

Abstract

The application discloses a kind of ground consolidation solution and preparation method and application thereof, belong to sand ground consolidation technical field.Ground consolidation solution is composed of bacteria solution, cementing fluid and polycarboxylate water reducing agent, wherein bacteria solution is composed of bacteria capable of producing urease;The volume ratio of bacteria solution and cementing fluid is 1:2~1:5;The concentration of polycarboxylate water reducing agent effective component polycarboxylic acid in cementing fluid is 5~25g / L.The application has the advantages of convenient construction, environment-friendly, long-acting time and low maintenance cost;In the application, most of the reinforcing material is inorganic cementing material, which is safe and non-toxic, harmless to human body and environment, and the compatibility of generated calcium carbonate with environment is also good.The ground treated by the ground consolidation solution of the application can meet the strength and deformation requirements, can enhance the stability of the dredged island under typhoon wave conditions, and make the ground of the dredged island meet the strength and stability requirements of infrastructure construction.

Description

Technical Field

[0001] This disclosure relates to the field of sandy soil foundation reinforcement technology, and in particular to a foundation reinforcement solution, its preparation method and application. Background Technology

[0002] Currently, traditional methods for treating island and reef foundations include physical reinforcement methods such as compaction and dynamic tamping, as well as grouting reinforcement. Mechanical reinforcement methods like compaction and dynamic tamping cause significant disturbance to the strata and require sophisticated engineering machinery. Furthermore, the materials used in island reclamation are mostly calcareous sand, which is easily broken under external forces, thus limiting the effectiveness of compaction reinforcement. Grouting reinforcement typically uses organic materials such as polyurethane and epoxy resin, or cement. Organic materials are difficult to degrade naturally, and chemical grouting materials are prone to aging in the special environment of islands and reefs characterized by high temperature, high humidity, high salinity, and high radiation. Their long-term reinforcement effectiveness and subsequent maintenance are difficult problems to solve. Cement reinforcement forms a permanent solidified body on the island and reef, significantly reducing the permeability of the sandy soil foundation and having a significant impact on the fragile island and reef ecosystem.

[0003] Microbially induced calcium carbonate precipitation (MICP) based on urea hydrolysis works by using urease-producing bacteria to hydrolyze urea into carbonate and ammonium ions. The resulting carbonate ions combine with calcium ions in the environment, forming calcium carbonate precipitates as bacterial nuclei. This calcium carbonate then binds loose sand particles together, achieving a reinforcement effect. However, current MIP technology suffers from several drawbacks, including the need for multiple reinforcement cycles, low material utilization, susceptibility to clogging, and unsatisfactory reinforcement results. Current MIP reinforcement processes typically involve alternating injection of bacterial solution and cementing solution into the soil using a two-phase injection method. The cementing solution mainly consists of urea and calcium chloride. Due to bacterial inactivation after a period of time and the washing away of the injected bacterial solution by subsequent cementing solutions, urea and calcium chloride are often not fully utilized, resulting in low material utilization. During grouting, the reaction often occurs first near the injection port, causing calcium carbonate to clog the grouting site, leading to uneven reinforcement and unsatisfactory results. Summary of the Invention

[0004] This disclosure provides a foundation reinforcement solution, its preparation method, and its application, in order to at least solve one of the technical problems existing in the prior art.

[0005] According to a first aspect of this disclosure, a foundation reinforcement solution is provided.

[0006] A foundation reinforcement solution, comprising a bacterial solution, a cementing solution, and a polycarboxylate superplasticizer, wherein the bacterial solution is composed of bacteria capable of producing urease; the volume ratio of the bacterial solution to the cementing solution is 1:2 to 1:5; and the concentration of the effective component of the polycarboxylate superplasticizer, polycarboxylate, in the cementing solution is 5 to 25 g / L.

[0007] In one embodiment, the bacteria is Pasteurella multocida; the bacterial activity is 15 KU / L.

[0008] In one embodiment, the bacterial culture is prepared by culturing bacteria in a liquid culture medium comprising 20 g / L yeast extract, 10 g / L ammonium sulfate and 15.8 g / L Tris-base.

[0009] In one embodiment, the volume ratio of the polycarboxylate superplasticizer to the binder is 1%~5%:1;

[0010] The volume ratio of the bacterial solution to the cementing solution is 1:3.

[0011] In one embodiment, the cementing solution is composed of a mixture of calcium chloride, urea, and seawater; wherein the concentrations of calcium chloride and urea are both 1 mol / L.

[0012] In one embodiment, the polycarboxylic acid has a comb-like structure and an average molecular weight of 50,000.

[0013] In one embodiment, the volume ratio of the polycarboxylate superplasticizer to the binder is 2%~3%:1;

[0014] The concentration of polycarboxylic acid, the active ingredient in the polycarboxylic acid water-reducing agent, in the cementitious solution is 10~15 g / L.

[0015] Secondly, this application provides a method for preparing the aforementioned foundation reinforcement solution, comprising the following steps:

[0016] Step 1): Cultivate bacteria that can produce urease and add seawater to obtain a bacterial solution;

[0017] Step 2): Prepare the cementing solution using seawater;

[0018] Step 3) Add the polycarboxylate superplasticizer to the cementitious liquid in Step 2);

[0019] Step 4) Add the bacterial solution obtained in Step 1) to the cementing solution in Step 3) to prepare the foundation reinforcement solution.

[0020] In one possible implementation, step 1) includes:

[0021] Step 1-1): Prepare a liquid culture medium by mixing yeast extract, ammonium sulfate, and Tris-base, and sterilize the liquid culture medium at 121°C for 20 min, then cool it for later use; wherein, the concentration of yeast extract in the liquid culture medium is 20 g / L, the concentration of ammonium sulfate is 10 g / L, and the concentration of Tris-base is 15.8 g / L;

[0022] Steps 1-2): Inoculate the bacteria into liquid culture medium under sterile conditions. After inoculation, place the culture medium on a shaker and incubate at 30 °C with a rotation speed of 160-180 rpm.

[0023] Steps 1-3): Measure the activity of the bacterial solution using a conductivity meter and add seawater to prepare a bacterial solution with an activity of 15 kU / L.

[0024] In one embodiment, in step 2), calcium chloride and urea are weighed and added to seawater to prepare a cementing solution with a concentration of 1 mol / L calcium chloride and a concentration of 1 mol / L urea.

[0025] In step 3), when the polycarboxylate superplasticizer is added to the cementing solution in step 2), the concentration of the effective component of the polycarboxylate superplasticizer, polycarboxylate, in the cementing solution is 5~25g / L.

[0026] Thirdly, this application provides the application of the aforementioned foundation reinforcement solution in the foundation reinforcement of islands and reefs.

[0027] In one embodiment, the foundation reinforcement solution is sprayed onto the surface of the foundation of the island reef to be treated, and the reinforcement is carried out once every 24 hours, and the reinforcement is repeated multiple times.

[0028] The advantages of this application are: 1) This application is convenient to construct, environmentally friendly, effective, long-lasting, and low in maintenance cost; the majority of the reinforcing materials in this application are inorganic cementitious materials, and the bacteria and polycarboxylate additives are safe and non-toxic, posing no harm to the human body or the environment. The generated calcium carbonate also has good environmental compatibility. 2) The construction process of this application is simple, and most construction steps can be completed indoors. On-site, only the spraying of the foundation reinforcement solution is required, resulting in high on-site construction efficiency. A single worker can complete the foundation reinforcement work with the spraying machine. 3) The post-construction maintenance cost of this application is low. The foundation soil after reinforcement still has good permeability. After reinforcement, only the foundation reinforcement solution needs to be periodically injected into the foundation to maintain the foundation strength at a high level. 4) The foundation treated with the foundation reinforcement solution of this application can meet the strength and deformation requirements, enhance the stability of the reclaimed islands and reefs under typhoon and wave conditions, and enable the foundation of the reclaimed islands and reefs to meet the strength and stability requirements of infrastructure construction.

[0029] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this disclosure, nor is it intended to limit the scope of this disclosure. Other features of this disclosure will become readily apparent from the following description. Attached Figure Description

[0030] The above and other objects, features, and advantages of this disclosure will become readily apparent from the following detailed description of exemplary embodiments, taken in conjunction with the accompanying drawings. Several embodiments of this disclosure are illustrated in the drawings by way of example and not limitation, in which:

[0031] In the accompanying drawings, the same or corresponding reference numerals indicate the same or corresponding parts.

[0032] Figure 1 The graph shows the change of bacterial activity per unit concentration over time under different amounts of polycarboxylic acid added according to embodiments of this disclosure.

[0033] Figure 2 The graph shows the change in calcium ion precipitation rate over time under different amounts of polycarboxylic acid added according to embodiments of this disclosure.

[0034] Figure 3 The following diagrams illustrate the strength of sand columns under different amounts of polycarboxylate and different reinforcement cycles according to embodiments of this disclosure.

[0035] Figure 4 The stress-strain curves of foundation reinforcement solutions prepared with different amounts of polycarboxylic acid added according to embodiments of the present disclosure are shown in the unconfined compression test of sand columns under 5 reinforcement conditions.

[0036] Figure 5 The diagram shows the relationship between the depth of the sand column and the calcium carbonate content distribution obtained under different concentrations of polycarboxylic acid addition in embodiments of this disclosure.

[0037] Figure 6 The diagram shows the relationship between the calcium carbonate precipitation ratio and time under different volume ratios of bacterial solution and cementing solution according to embodiments of this disclosure. Detailed Implementation

[0038] To make the objectives, features, and advantages of this disclosure more apparent and understandable, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0039] Polycarboxylic acid (PCA) is a comb-like or dendritic high-molecular-weight organic compound. Its main chain can adsorb onto the surface of soil particles, and its branches contain a large number of carboxylic acid groups, which can undergo complexation reactions with calcium ions. The addition of PCA molecules can slow down the early precipitation of calcium carbonate in the reaction system, and even when the bacterial solution and cementing solution are mixed and injected into the reinforced soil, clogging will not occur. In addition, PCA molecules can act as nucleation templates for calcium carbonate. Within an appropriate concentration range, the addition of PCA molecules can increase the size of the calcium carbonate precipitate crystals formed in the reaction, which is beneficial to improving the reinforcement effect. In the reaction system without PCA, bacteria generally act as nuclei for calcium carbonate precipitation, leading to rapid bacterial death and insufficient utilization of raw materials. The addition of PCA can prolong the action time of bacteria, and calcium ions can be completely precipitated within a 24-hour reaction cycle. Therefore, the microbial foundation treatment technology with added PCA can greatly simplify the grouting process and make full use of raw materials, making it highly applicable in island and reef scenarios where labor costs are high, resources are limited, and the ecology is fragile.

[0040] Based on this, this application provides a foundation reinforcement solution comprising a bacterial solution, a cementing solution, and a polycarboxylate superplasticizer, wherein the bacterial solution is composed of bacteria capable of producing urease; the volume ratio of the bacterial solution to the cementing solution is 1:2 to 1:5; and the concentration of the effective component polycarboxylate superplasticizer, polycarboxylate, in the cementing solution is 5 to 25 g / L (i.e., the mass ratio of the effective component polycarboxylate to the volume ratio of the cementing solution).

[0041] In one embodiment, the volume ratio of polycarboxylate superplasticizer to cementitious liquid is 1%~5%:1; more preferably, the volume ratio of polycarboxylate superplasticizer to cementitious liquid is 2%~3%:1; and the volume ratio of bacterial solution to cementitious liquid is 1:3.

[0042] In one embodiment, the bacteria is *Pasteurella pasporioides*, purchased from the China General Microbiological Culture Collection Center (CGMCC) under number 1.3687. This bacterium is capable of producing high levels of urease, which can hydrolyze urea into carbonate and ammonium particles. The preferred bacterial activity is 15 KU / L.

[0043] In one embodiment, the bacterial culture is prepared by culturing bacteria in a liquid culture medium consisting of 20 g / L yeast extract, 10 g / L ammonium sulfate and 15.8 g / L Tris-base (tris(hydroxymethyl)aminomethane); the culture medium is sterilized at 121°C for 20 min.

[0044] In one embodiment, the cementing solution is composed of a mixture of calcium chloride, urea, and seawater; wherein the concentrations of calcium chloride and urea are both 1 mol / L.

[0045] In one embodiment, the polycarboxylic acid has a comb-like structure and an average molecular weight of 50,000.

[0046] In one embodiment, the concentration of polycarboxylic acid, the active ingredient in the polycarboxylic acid water-reducing agent, in the cementitious solution is 10-15 g / L.

[0047] Secondly, this application also provides a method for preparing a foundation reinforcement solution, comprising the following steps:

[0048] Step 1): Cultivate bacteria that can produce urease and add seawater to obtain a bacterial solution;

[0049] Step 2): Prepare the cementing solution using seawater;

[0050] Step 3) Add the polycarboxylate superplasticizer to the cementitious liquid in Step 2);

[0051] Step 4) Add the bacterial solution obtained in Step 1) to the cementing solution in Step 3) to prepare the foundation reinforcement solution.

[0052] Step 1) includes: Step 1-1): Prepare a liquid culture medium by mixing yeast extract, ammonium sulfate and Tris-base, and sterilize the liquid culture medium at 121℃ for 20 min, then cool it for later use; wherein the concentration of yeast extract in the liquid culture medium is 20 g / L, the concentration of ammonium sulfate is 10 g / L and the concentration of Tris-base is 15.8 g / L.

[0053] Steps 1-2): Inoculate the bacteria into liquid culture medium under sterile conditions. After inoculation, place the culture medium on a shaker and incubate at 30°C with a rotation speed of 160-180 rpm.

[0054] Steps 1-3): Measure the activity of the bacterial solution using a conductivity meter and add seawater to prepare a bacterial solution with an activity of 15 kU / L.

[0055] In one embodiment, in steps 1-3), the bacterial activity is measured by the following method: the bacterial solution is mixed with 1.5 mol / L urea solution at a volume ratio of 1:9, and then the bacterial activity is measured using a conductivity meter.

[0056] In one embodiment, in step 2), calcium chloride and urea are weighed and added to seawater to prepare a cementing solution with a concentration of 1 mol / L calcium chloride and a concentration of 1 mol / L urea. In step 3), when the polycarboxylate superplasticizer is added to the cementing solution of step 2), the concentration of the effective component of the polycarboxylate superplasticizer, polycarboxylate, in the cementing solution is 5~25 g / L.

[0057] Thirdly, this application provides the application of a foundation reinforcement solution in the reinforcement of island and reef foundations. The foundation reinforcement solution is sprayed onto the surface of the island or reef foundation to be reinforced, with reinforcement applied once every 24 hours, and repeated multiple times. Preferably, the reinforcement is repeated 5 times.

[0058] This application modifies microbially induced calcium carbonate precipitation using polycarboxylic acid, slowing down the initial precipitation rate and increasing the final precipitation rate. After five reinforcement cycles, the unconfined compressive strength of the sand can reach over 2 MPa. This method simplifies the traditional two-phase injection microbial reinforcement process, improves raw material utilization, and produces a cementing material with good environmental compatibility, making it highly applicable in island and reef environments characterized by limited manpower, scarce resources, and fragile ecosystems.

[0059] The method for activating the microbial strain in this application is as follows: Prepare 100 mL of liquid culture medium, the specific components of which are 20 g / L yeast extract, 10 g / L ammonium sulfate, and 15.8 g / L Tris-base. Place the prepared culture medium in an autoclave and sterilize it at 121℃ for 20 min, then cool it for later use.

[0060] Bacterial activation was performed under aseptic conditions. First, the upper part of the ampoule containing the bacteria was wiped with 75% alcohol. The upper part of the ampoule was then heated with an alcohol lamp, and water was dripped on it to break it. The inner tube was removed with tweezers, and the cotton plug was opened. 1 mL of culture medium was drawn up with a pipette and injected into the tube. The tube was then allowed to stand to completely dissolve the lyophilized powder. The bacteria were then transferred into a culture medium containing 100 mL of culture medium and incubated in a shaker at 30°C and 180 rpm for 48 h. Bacterial activation was then complete.

[0061] After the bacteria are activated, a 30% glycerol solution is prepared in advance and sterilized. The 30% glycerol solution is then mixed with the bacterial solution at a 1:1 ratio. The mixture is then transferred evenly into 2 mL cryovials and stored at -80°C. The cryovials can be stored for a long time.

[0062] The method for bacterial expansion culture in this application is as follows: Prepare 200 mL of liquid culture medium, sterilize it in an autoclave, place it in a clean bench, and simultaneously turn on the ultraviolet lamp to cool the culture medium to room temperature. Take out 2 mL of frozen bacterial culture from a -80℃ freezer, wait for the bacterial culture to warm to room temperature, and then inoculate the bacterial culture into the culture medium using a pipette. Then, incubate it in a shaker for 24 h. Afterward, inoculate the bacterial culture into new culture medium at an inoculation ratio of 2% to expand the culture. The culture is ready for use when the urease activity of the bacterial culture reaches 15 kU / L or higher.

[0063] In this application, *Pasteurella pasporioides* can be preserved for long-term use after activation and expansion culture at the China General Microbiological Culture Collection Center (CGMCC1.3687). The yeast extract, ammonium sulfate, Tris-base, calcium chloride, urea, and other chemical materials in the culture medium and cementing solution can all be purchased from general chemical reagent companies. The polycarboxylate superplasticizer is a common concrete superplasticizer material with a density of 1 g / ml and an effective polycarboxylate content of 50% (by mass), and can be purchased from general construction markets. The high-temperature sterilizer, aseptic operating table, shaker, and other equipment used for cultivation are all commercially available equipment.

[0064] The present application will be further described below with reference to specific embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and should not be used to limit the scope of protection of the present application.

[0065] Example 1

[0066] A polycarboxylate-modified microbial foundation reinforcement method (i.e., island and reef foundation reinforcement method) for island and reef environments is disclosed. The island and reef foundation to be treated is calcareous sand with a specific gravity of 2.804, a maximum void ratio of 1.423, a minimum void ratio of 0.942, and a density of approximately 50%. The foundation, which is 6 m in length and width and 30 cm in height, needs to be reinforced. Calculations show that 10.8 cubic meters (13.8 tons) of calcareous sand needs to be treated. The specific steps are as follows:

[0067] (1) Prepare 500 L of liquid culture medium, which consists of 20 g / L yeast extract, 10 g / L ammonium sulfate, and 15.8 g / L Tris-base. Sterilize the prepared culture medium at 121 °C for 20 min, and then cool it for later use. Inoculate 10 L of bacterial solution into the culture medium at a 2% inoculation ratio, and incubate it in a shaker at 30 °C and 180 rpm for 24 h.

[0068] (2) The activity of the bacterial solution was measured by a conductivity meter. 250 L of bacterial solution with an activity of 15 kU / L was prepared by adding seawater. The remaining bacterial solution could be stored in a refrigerator at 4 ℃ for a short period of time.

[0069] (3) Weigh 82.5 kg of calcium chloride and 45.05 kg of urea, add them to about 750 L of seawater to prepare a cementing solution containing 1 mol / L calcium chloride and 1 mol / L urea. The volume of the cementing solution is 750 L.

[0070] (4) Add 22.5 L of polycarboxylate superplasticizer to the cementing solution. The concentration of the effective component polycarboxylate is 15 g / L (i.e., m (effective polycarboxylate) / V (cementing solution)). The average molecular weight of the effective component polycarboxylate is 50,000.

[0071] (5) Mix the bacterial solution prepared in (2) with the cementing solution to form a foundation reinforcement solution. The prepared foundation reinforcement solution should be used as soon as possible.

[0072] (6) The foundation reinforcement solution is evenly sprayed onto the surface of the foundation to be treated by surface spraying. A large flow spray grouting machine or multiple small flow spray grouting machines can be used to complete the spraying of the foundation reinforcement solution within 30 minutes.

[0073] (7) After spraying, let it stand for 24 hours to complete one round of reinforcement.

[0074] (8) After five repeated reinforcements, the unconfined compressive strength under laboratory conditions can reach more than 2 MPa. During the reinforcement process, the foundation strength should be monitored in real time, and the reinforcement can be terminated in advance after the reinforcement target is reached.

[0075] Example 2

[0076] This Example 2 is largely the same as Example 1, except that the volume ratio of polycarboxylate superplasticizer to cementitious liquid is 1%:1, and the concentration of the active ingredient polycarboxylate is 5g / L.

[0077] Example 3

[0078] This Example 3 is largely the same as Example 1, except that the volume ratio of polycarboxylate superplasticizer to binder is 2%:1, and the concentration of the active ingredient polycarboxylate is 10g / L.

[0079] Example 4

[0080] This Example 4 is largely the same as Example 1, except that the volume ratio of polycarboxylate superplasticizer to binder is 4%:1, and the concentration of the active ingredient polycarboxylate is 20g / L.

[0081] Example 5

[0082] This Example 5 is largely the same as Example 1, except that the volume ratio of polycarboxylate superplasticizer to cementitious liquid is 5%:1, and the concentration of the active ingredient polycarboxylate is 25g / L.

[0083] Comparative Example 1

[0084] Comparative Example 1 is largely the same as Example 1, except that the amount of polycarboxylate superplasticizer added is 0%.

[0085] The effects of different amounts of polycarboxylic acid added in the foundation reinforcement solutions prepared in Examples 1-5 and Comparative Example 1 on bacterial activity, calcium ion precipitation, and sand column strength are further investigated below. The results are as follows: Figure 1-3 As shown, where Figure 1This graph shows the change in bacterial activity per unit concentration over time under different amounts of polycarboxylic acid added. This is because the bacteria can produce a high level of urease. Figure 1 Specifically, it shows the relationship between urease activity and time (Normalized Urease Activity versus time). Figure 1 It can be seen that when the polycarboxylic acid addition is 0% (Comparative Example 1), that is, when no polycarboxylic acid is added to the foundation reinforcement solution, the bacterial activity in the foundation reinforcement solution decreases significantly over time, and is lower than the effect of foundation reinforcement solutions containing 1%-5% polycarboxylic acid on bacterial activity. When the polycarboxylic acid addition is 1%-5%, the difference in effect on bacterial activity over time is not significant.

[0086] Figure 2 This is a graph showing the change in calcium ion precipitation rate (i.e., the conversion rate of calcium ions to calcium carbonate) over time for different amounts of polycarboxylic acid added. Figure 2 It can be seen that different amounts of polycarboxylate have a significant impact on calcium ion precipitation. Adding 1%-5% polycarboxylate results in a higher calcium ion precipitation rate than with 0% polycarboxylate. Furthermore, the calcium ion precipitation rates with 2% and 3% polycarboxylate additions are significantly higher than those with 4% and 1% additions. And the calcium ion precipitation rates with 1% and 4% polycarboxylate additions are significantly higher than those with 5% addition.

[0087] Figure 3 This study investigates the effect of foundation reinforcement solutions prepared with different amounts of polycarboxylic acid added on the strength of sand columns under different treatment times. Figure 3 As can be seen, the strength of the sand column increases linearly with the increase in the number of reinforcements, and from... Figure 3 It can also be seen that in the first three reinforcements, the effects of polycarboxylate additions of 1%, 3% and 5% on the strength of the sand column were not significant. However, in the fifth reinforcement, different amounts of polycarboxylate additions had a significant effect on the strength of the sand column. The strength of the sand column with 3% polycarboxylate addition was much greater than that with 1% and 5% polycarboxylate addition.

[0088] Figure 4 This is a graph showing the stress-strain curves of foundation reinforcement solutions prepared with different amounts of polycarboxylic acid added during unconfined compression tests on sand columns after five reinforcement cycles. Figure 4 The terms 1-5, 3-5, and 5-5 refer to 1% polycarboxylate reinforced with 5 layers of reinforcement, 3% polycarboxylate reinforced with 5 layers of reinforcement, and 5% polycarboxylate reinforced with 5 layers of reinforcement, respectively. Figure 4As can be seen, with the increase of polycarboxylate concentration, the strength of the sand column first increases and then decreases, and the difference in stiffness (i.e., stress / strain) of the sand column is small under different addition conditions. Furthermore, from... Figure 4 It can also be seen that the sand column treated with 3% polycarboxylate additive has the highest stress.

[0089] Figure 5 These are curves showing the relationship between the depth and internal CaCO3 (Calcium Carbonate Content, abbreviated as "CCC") distribution of sand columns treated with foundation reinforcement solutions prepared at different concentrations (3% - Example 1, 1% - Example 2, 5% - Example 5, and 0% - Comparative Example 1). Please refer to the following for details. Figure 5 A- Figure 5 D, Figure 5 A is a graph showing the relationship between the depth of a sand column treated with a foundation reinforcement solution and the distribution of CaCO3 content inside the column when the polycarboxylic acid content is 0%. Figure 5 B is a graph showing the relationship between the depth of the sand column treated with the foundation reinforcement solution and the distribution of CaCO3 content inside when the polycarboxylic acid content is 1%. Figure 5 C is a graph showing the relationship between the depth of the sand column treated with the foundation reinforcement solution and the distribution of CaCO3 content inside when the polycarboxylic acid content is 3%. Figure 5 D is a graph showing the relationship between the depth of a sand column treated with a foundation reinforcement solution and the distribution of CaCO3 content inside the column when the polycarboxylic acid content is 5%. Figure 5 In case A, when the polycarboxylic acid addition was 0%, the surface CaCO3 content of the sand column was relatively high during the first foundation reinforcement, much higher than the CaCO3 content of the foundation reinforcement solutions containing 1%, 3%, and 5% polycarboxylic acid during the first foundation reinforcement. Furthermore, with the third and fifth reinforcements, the CaCO3 content decreased from... Figure 5 As can be seen in Figure A, a large amount of CaCO3 precipitate accumulates and clogs the surface of the sand column. Furthermore, as the depth of the sand column increases, the CaCO3 precipitate shows a pattern of more precipitate at the top and less at the bottom, indicating an uneven distribution of CaCO3 precipitate within the sand column and an unsatisfactory reinforcement effect.

[0090] from Figure 5 B- Figure 5 As can be seen from D, when the polycarboxylate addition amounts are 1%, 3%, and 5%, in the first (1time), third (3times), and fifth (5times) reinforcements, the CaCO3 distribution within the sand column is relatively uniform after each reinforcement. Furthermore, as the sand column depth increases, the CaCO3 precipitation distribution within the sand column becomes more uniform, and the sand column is relatively stable. Especially... Figure 5 C, from Figure 5As can be seen from C, when the polycarboxylic acid content is 3%, the prepared foundation reinforcement solution, when used for foundation reinforcement, shows that, with the increase of the number of reinforcements, the distribution of CaCO3 in the sand column is relatively uniform, and the amount of CaCO3 precipitation in the sand column is the largest during the 5th reinforcement, thus the foundation stability obtained by this treatment is the best.

[0091] Furthermore, we investigated the relationship between the CaCO3 precipitation ratio and time under different volume ratios of bacterial solution and cementitious solution when the polycarboxylic acid addition was 1%. The results are as follows: Figure 6 As shown. From Figure 6 It can be seen that when the volume ratio of bacterial solution to cementing solution is 1:1, CaCO3 begins to precipitate directly. The precipitation is too rapid, and a large amount of CaCO3 will clog the surface of the sand column. However, when the volume ratio of bacterial solution to cementing solution is 1:10, the proportion of CaCO3 precipitation is relatively small within 0-10 hours, less than when the volume ratio is 1:2-1:5. Furthermore, some CaCO3 precipitation still fails to completely precipitate over time, resulting in an unsatisfactory precipitation effect.

[0092] When the volume ratio of bacterial solution to cementing solution is 1:2 to 1:5, within 0-10 hours, the precipitation of calcium carbonate increases slowly with time, slowing down the initial precipitation rate. Beyond 10 hours, the final precipitation rate of calcium carbonate is high, reaching 100% complete precipitation. Specifically, within 10 hours, a volume ratio of 1:3 for CaCO3 precipitation is moderate, neither too fast nor too slow. Around 10 hours, the precipitation ratios for 1:2, 1:3, and 1:5 reach consistency. At 24 hours, 100% precipitation is maintained for volume ratios of 1:3 and 1:5. Finally, at 35 hours, the precipitation ratios for 1:2, 1:3, and 1:5 reach consistency, achieving 100% precipitation. Therefore, when the volume ratio of bacterial solution to cementing solution is 1:3, the prepared foundation reinforcement solution has the best effect, and when reinforcing the foundation, the precipitation of calcium carbonate in the sand column is the best.

[0093] Through the above implementation methods, the treated foundation can meet the strength and deformation requirements, enhance the stability of the reclaimed islands and reefs under typhoon and wave conditions, and enable the foundation of the reclaimed islands and reefs to meet the strength and stability requirements for infrastructure construction.

[0094] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this disclosure can be achieved, and this is not limited herein.

[0095] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this disclosure. Furthermore, the described specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples. Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0096] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A foundation reinforcement solution, characterized in that: The foundation reinforcement solution comprises a bacterial solution, a cementing solution, and a polycarboxylate superplasticizer. The bacterial solution is composed of bacteria capable of producing urease. The volume ratio of the bacterial solution to the cementing solution is 1:2 to 1:

5. The concentration of the effective component of the polycarboxylate superplasticizer, polycarboxylate, in the cementing solution is 5 to 25 g / L. The volume ratio of the polycarboxylate superplasticizer to the cementing solution is 1% to 5% to 1. The cementing solution is composed of a mixture of calcium chloride, urea and seawater; wherein the concentration of both calcium chloride and urea is 1 mol / L.

2. The foundation reinforcement solution according to claim 1, characterized in that: The bacteria were Pasteurella multocida; the bacterial activity was 15 KU / L.

3. The foundation reinforcement solution according to claim 1, characterized in that: The bacterial culture was prepared by culturing bacteria in a liquid culture medium, which consisted of 20 g / L yeast extract, 10 g / L ammonium sulfate and 15.8 g / L Tris-base.

4. The foundation reinforcement solution according to claim 1, characterized in that: The volume ratio of the bacterial solution to the cementing solution is 1:

3.

5. The foundation reinforcement solution according to claim 1, characterized in that: The polycarboxylic acid has a comb-like structure and an average molecular weight of 50,000.

6. The foundation reinforcement solution according to claim 1, characterized in that: The volume ratio of the polycarboxylate superplasticizer to the cementitious liquid is 2%~3%:1; The concentration of polycarboxylic acid, the active ingredient in the polycarboxylic acid water-reducing agent, in the cementitious solution is 10~15 g / L.

7. The method for preparing the foundation reinforcement solution according to any one of claims 1-6, characterized in that: Includes the following steps: Step 1): Cultivate bacteria that can produce urease and add seawater to obtain a bacterial solution; Step 2): Prepare the cementing solution using seawater; Step 3): Add the polycarboxylate superplasticizer to the cementitious liquid in Step 2); Step 4): Add the bacterial solution obtained in Step 1) to the cementing solution in Step 3) to prepare the foundation reinforcement solution.

8. The preparation method according to claim 7, characterized in that: Step 1) includes: Step 1-1): Prepare a liquid culture medium by mixing yeast extract, ammonium sulfate, and Tris-base, and sterilize the liquid culture medium at 121°C for 20 min, then cool it for later use; wherein, the concentration of yeast extract in the liquid culture medium is 20 g / L, the concentration of ammonium sulfate is 10 g / L, and the concentration of Tris-base is 15.8 g / L; Steps 1-2): Inoculate the bacteria into liquid culture medium under sterile conditions. After inoculation, place the culture medium on a shaker and incubate at 30°C with a rotation speed of 160-180 rpm. Steps 1-3): Measure the activity of the bacterial solution using a conductivity meter and add seawater to prepare a bacterial solution with an activity of 15 kU / L.

9. The preparation method according to claim 7, characterized in that: In step 2), calcium chloride and urea are weighed separately, added to seawater, and prepared as a cementing solution with a concentration of 1 mol / L calcium chloride and a concentration of 1 mol / L urea. In step 3), when the polycarboxylate superplasticizer is added to the cementing solution in step 2), the concentration of the effective component of the polycarboxylate superplasticizer, polycarboxylate, in the cementing solution is 5~25g / L.

10. The application of the foundation reinforcement solution according to any one of claims 1-6 in the foundation reinforcement of islands and reefs.

11. The application according to claim 10, characterized in that: The foundation reinforcement solution is sprayed onto the surface of the island and reef foundation to be treated, and the reinforcement is carried out once every 24 hours, and the reinforcement is repeated multiple times.

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