Method for solidifying residual granite soil

Abstract

The application provides a method for solidifying granite residual soil. The method comprises the following steps: providing bacillus; and sequentially pouring the bacillus, a fixing agent and a cementing liquid into the granite residual soil; wherein the bacillus is selected from one or more of bacillus marinus, bacillus arthriticus and bacillus terrae. The method for solidifying granite residual soil of the application uses the bacterial liquid of three kinds of bacillus capable of producing urease screened from nature to pour the granite residual soil, so that the granite residual soil forms solidified granite residual soil with high uniaxial compressive strength. The method can quickly and efficiently stick loose sand particles together, thereby improving the strength of the foundation sand; in addition, the strains used in the application are isolated from nature, and the strains will not pollute the natural environment.

Description

Technical Field

[0001] This invention relates to the field of foundation reinforcement technology, and in particular to a method for solidifying residual granite soil. Background Technology

[0002] Granite residual soil is a special geological material formed in arid and semi-arid desert climates. It is also the most widely distributed, abundant, and readily available inexpensive material. However, granite residual soil has a loose structure, low clay content and lack of cohesion, poor stability, and low bearing capacity. Furthermore, it is subject to frequent wind transport and erosion, resulting in high fluidity. In addition, granite residual soil has a high salt and alkali content, making it inaccessible to large construction equipment or prohibitively expensive to use. Due to these limitations, general foundation treatment techniques are not applicable in granite residual soil areas.

[0003] Microbially Induced Calcite Precipitation (MICP) is essentially a process where a certain type of bacteria in nature produces urease through its metabolism, which decomposes urea. The carbonate ions produced after urea decomposition can combine with free metal cations in nature to form gel crystals.

[0004] Currently, researchers often spray Pasteurella multocida bacterial solution onto the surface of granite residual soil, utilizing Pasteurella multocida's ability to produce urease to improve the strength of granite residual soil; however, it remains unknown whether other strains besides Pasteurella multocida can also be used to reinforce granite residual soil. Summary of the Invention

[0005] Based on this, the present invention provides a method for solidifying granite residual soil using a bacterial solution of one or more strains of Bacillus marinum, Bacillus aureus, and Bacillus strophariae.

[0006] The specific technical solution is as follows:

[0007] According to one aspect of the present invention, a method for solidifying residual granite soil is provided, comprising the following steps:

[0008] Provide Bacillus; and

[0009] The Bacillus, fixative, and cementing solution were sequentially injected into the residual soil of the granite.

[0010] The Bacillus is selected from one or more of Bacillus aquaticus, Bacillus argentis, and Bacillus stropharia.

[0011] In one embodiment, the Bacillus marinum is deposited under the accession number CGMCC No. 18068.

[0012] In one embodiment, the Bacillus argentea has the accession number CGMCC No. 18069.

[0013] In one embodiment, the soil Bacillus has the accession number CGMCC No. 18070.

[0014] In one embodiment, after the step of providing Bacillus and before infusing the Bacillus, the method further includes:

[0015] Single colonies of Bacillus were inoculated into the fermentation medium and cultured at 25℃~37℃ and 150rpm~250rpm for 12h~60h.

[0016] In one embodiment, the fermentation medium is NH4-YE medium or salt medium.

[0017] In one embodiment, the fixative includes 0.04M to 0.06M CaCl2.

[0018] In one embodiment, the cementing solution includes 0.4M to 0.6M CaCl2 and 0.4M to 0.6M urea.

[0019] In one embodiment, the ratio of the Bacillus bacterial suspension, the fixative, and the cementing solution is (40 mL to 160 mL): (0.01 M to 0.1 M): (140 mL to 160 mL).

[0020] In one embodiment, the slurry filling rate of the Bacillus bacterial solution is 0.05 mL / min to 1.00 mL / min; and / or

[0021] The grouting rate of the fixative is 0.05 mL / min to 1.00 mL / min; and / or

[0022] The grouting rate of the cementing solution is 0.05 mL / min to 0.15 mL / min.

[0023] Compared with traditional technologies, the present invention has the following beneficial effects:

[0024] The method for solidifying granite residual soil of the present invention uses bacterial solutions of three types of urease-producing Bacillus strains screened from nature to infuse the granite residual soil, thereby forming solidified granite residual soil with high uniaxial compressive strength. This method can quickly and efficiently bind loose sand particles together, thereby improving the strength of the foundation sand; furthermore, the bacterial strains used in this invention are isolated from nature and will not pollute the natural environment. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 Electron micrograph of Bacillus aquimaris H216;

[0027] Figure 2 Electron micrograph of Bacillus aryabhattai H961;

[0028] Figure 3 Electron micrograph of Terribacillus saccharophilus H986;

[0029] Figure 4 This is a statistical chart showing the bacterial concentrations of the three strains screened in this invention in NH4-YE medium and salt medium.

[0030] Figure 5 The urease activity statistics of the three strains screened in this invention in NH4-YE medium and salt medium are shown in the figure.

[0031] Figure 6 This is a statistical graph showing the urease activity of the three strains screened in this invention under different culture temperature conditions.

[0032] Figure 7 This is a statistical graph showing the urease activity of the three strains screened in this invention under different pH culture conditions.

[0033] Figure 8 This is a particle size distribution diagram of the granite residual soil sample used in Example 1;

[0034] Figure 9 Scanning electron microscope image of a sand column perfused with Bacillus aquimaris H216;

[0035] Figure 10 Scanning electron microscope image of a sand column perfused with Bacillus aryabhattai H961;

[0036] Figure 11Scanning electron microscope image of a sand column after perfusion with soil spore bacterium Terribacillus saccharophilus H986;

[0037] Figure 12 The uniaxial compressive strength of granite residual soil columns infused with the three strains screened in this invention is statistically shown. Detailed Implementation

[0038] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. Unless otherwise specifically stated, all raw materials, reagents, instruments, and equipment used in this invention are commercially available or can be prepared by existing methods.

[0040] the term

[0041] Unless otherwise stated or in case of contradiction, the terms or phrases used herein shall have the following meanings:

[0042] The terms "and / or," "or / and," and "and / or" as used herein include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected using at least two conjunctions selected from "and / or," "or / and," and "and / or," it should be understood that in this invention, the technical solution undoubtedly includes solutions connected by "logical AND," and also undoubtedly includes solutions connected by "logical OR." For example, "A and / or B" includes three parallel solutions: A, B, and A+B. For example, the technical solution of "A, and / or, B, and / or, C, and / or, D" includes any one of A, B, C, and D (that is, a technical solution that is connected by "logical OR"), as well as any and all combinations of A, B, C, and D, that is, combinations of any two or three of A, B, C, and D, and also combinations of all four of A, B, C, and D (that is, a technical solution that is connected by "logical AND").

[0043] In this invention, terms such as "multiple", "various", "multiple times", and "multi-source" are used, and unless otherwise specified, they refer to a quantity greater than or equal to 2. For example, "one or more" means one or more types.

[0044] The terms “combinations of,” “any combination of,” and “any combination of” used in this article include all suitable combinations of any two or more of the listed items.

[0045] In this document, the term "suitable" as used in phrases such as "suitable combination," "suitable method," and "any suitable method" refers to the ability to implement the technical solution of this invention, solve the technical problem of this invention, and achieve the expected technical effect of this invention.

[0046] In this article, terms such as "preferred," "better," "more suitable," and "ideal" are merely used to describe implementation methods or examples that achieve better results, and should be understood not to limit the scope of protection of this invention.

[0047] In this invention, terms such as "further," "even more," and "particularly" are used for descriptive purposes and to indicate differences in content, but should not be construed as limiting the scope of protection of this invention.

[0048] In this invention, "optionally," "optionally," and "optional" mean that they are optional, that is, they are selected from either "with" or "without." If multiple "options" appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "option" is independent.

[0049] In this invention, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions that include the listed features.

[0050] In this invention, numerical intervals (i.e., numerical ranges) are involved. Unless otherwise specified, the selected numerical distributions within the aforementioned numerical intervals are considered continuous and include the two endpoints (i.e., the minimum and maximum values) of the numerical range, as well as every value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints. In this document, this is equivalent to directly listing every integer. For example, if t is an integer selected from 1 to 10, it means that t is any integer selected from the group of integers consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Furthermore, when multiple ranges are provided to describe features or characteristics, these ranges can be merged. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0051] Unless otherwise specified, the temperature parameters in this invention can be either constant temperature treatment or variations within a certain temperature range. It should be understood that the constant temperature treatment allows temperature fluctuations within the precision range controlled by the instrument. Fluctuations are permitted within ranges such as ±5℃, ±4℃, ±3℃, ±2℃, and ±1℃.

[0052] Some embodiments of the present invention provide a method for solidifying residual granite soil.

[0053] In some embodiments, the method for solidifying granite residual soil includes steps S10 and S30.

[0054] S10: Provides Bacillus; and

[0055] S30: The bacterial solution of the Bacillus, the fixative and the cementing solution are sequentially injected into the residual soil of the granite;

[0056] In step S10, the Bacillus is selected from one or more of Bacillus aquaticus, Bacillus argentis, and Bacillus stropharia.

[0057] Understandably, the bacterial solution can be any one of Bacillus aquaticus, Bacillus argentis, and Bacillus stolonifer; or a mixture of any two of them; or a mixture of all three strains.

[0058] In some specific examples, the marine Bacillus was selected from Bacillus aquimaris H216, which was deposited on July 4, 2019, at the China General Microbiological Culture Collection Center (address: No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing, 100101, China), with accession number CGMCC No. 18068.

[0059] In some specific examples, the 16S DNA sequence of the aforementioned Bacillus marineis is shown in SEQ ID NO.1.

[0060] In addition, *Bacillus marineii* can also be selected from sequences whose 16S DNA sequence is substantially similar to that of SEQ ID NO. 1. "Substantially similar" means that the given nucleic acid or amino acid sequence shares at least 95% identity with the reference sequence, for example, 96%, 97%, 98%, 98.5%, 99%, or 99.5%. Alternatively, it means that the given nucleic acid or amino acid sequence differs from the reference sequence in 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 nucleic acids or amino acids.

[0061] In some specific examples, Bacillus aryabhattai was selected from Bacillus aryabhattai H961, which was deposited on July 4, 2019, at the China General Microbiological Culture Collection Center (address: No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing, 100101, China), with accession number CGMCC No. 18069.

[0062] In some specific examples, the 16S DNA sequence of the aforementioned Bacillus argentea is shown in SEQ ID NO.2.

[0063] In some specific examples, the soil Bacillus was selected from Terribacillus saccharophilus H986, which was deposited on July 4, 2019, at the China General Microbiological Culture Collection Center (address: No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing, 100101, China), with accession number CGMCC No. 18070.

[0064] In some specific examples, the 16S DNA sequence of the aforementioned soil Bacillus is shown in SEQ ID NO.3.

[0065] In some embodiments, the above-described method for consolidating residual granite soil further includes step S20:

[0066] Single colonies of Bacillus were inoculated into the fermentation medium and cultured at 25℃~37℃ and 150rpm~250rpm for 12h~60h.

[0067] In one preferred example, in step S20, a single colony of Bacillus is inoculated into the fermentation medium and cultured at 30°C and 150 rpm to 250 rpm for 16 h; the bacterial culture is then collected.

[0068] In some embodiments, in step S20, the fermentation medium is NH4-YE medium or high-salt medium.

[0069] In some specific examples, the NH4-YE medium includes yeast extract and ammonium sulfate; the ratio of yeast extract to ammonium sulfate by mass volume is (10–20):10.

[0070] Understandably, the ratio of yeast extract to ammonium sulfate in NH4-YE medium is “(10-20):10”, which includes, but is not limited to, the point values ​​in the examples and the following point values: 10:10, 11:10, 12:10, 13:10, 14:10, 15:10, 16:10, 17:10, 18:10, 19:10, 20:10 and other specific ratios.

[0071] In some specific examples, the salt culture medium includes yeast extract and ammonium chloride; the ratio of yeast extract to ammonium chloride by mass volume is (10–20):10.

[0072] Understandably, the ratio of yeast extract to ammonium chloride in the salt culture medium is “(10-20):10”, which includes, but is not limited to, the point values ​​in the examples and the following point values: 10:10, 11:10, 12:10, 13:10, 14:10, 15:10, 16:10, 17:10, 18:10, 19:10, 20:10 and other specific ratios.

[0073] Furthermore, the pH of both the NH4-YE medium and the salt medium is 7.0–9.5. Understandably, controlling the pH of the fermentation medium within this range can promote the strain's ability to produce urease at a relatively low cost.

[0074] In some embodiments, in step S30, the fixative includes 0.04M to 0.06M CaCl2.

[0075] In some embodiments, the cementing solution includes 0.4M to 0.6M CaCl2 and 0.4M to 0.6M urea.

[0076] Microbial-induced calcium carbonate precipitation (MICP) technology allows specific microorganisms to utilize organic matter such as urea and calcium ion sources in the surrounding environment to generate calcium carbonate with cementing properties. Since the formation rate and strength of microbially generated calcium carbonate are controllable, it can act as a binder to bond loose sand grains into artificial gravel with controllable strength and permeability. Therefore, MICP holds promise for widespread application in concrete, sand, and silt consolidation.

[0077] The three Bacillus strains of the present invention can produce urease, thereby decomposing urea in the sandy environment into ammonium ions and carbon dioxide, while increasing the pH of the sandy environment around the strains; by injecting a fixative and cementing solution containing calcium ions into the sand, water-insoluble calcium carbonate salts can be generated, causing the surrounding sand grains to stick together.

[0078] In some embodiments, the ratio of the amount of Bacillus bacterial suspension, fixative, and cementing solution injected is (40 mL to 160 mL): (0.01 M to 0.1 M): (140 mL to 160 mL).

[0079] In some embodiments, the slurry filling rate of Bacillus bacterial solution is 0.05 mL / min to 1.00 mL / min. Preferably, the slurry filling rate is 0.5 mL / min.

[0080] In some embodiments, the grouting rate of the fixative is 0.05 mL / min to 1.00 mL / min. Preferably, the grouting rate of the fixative is 0.5 mL / min.

[0081] In some embodiments, the grouting rate of the cementing fluid is 0.05 mL / min to 0.15 mL / min. Preferably, the grouting rate of the cementing fluid is 0.1 mL / min.

[0082] Applying abundant and non-toxic microbial resources from nature to foundation reinforcement projects can effectively alter the mechanical properties of civil and geotechnical engineering, opening up new avenues for the field of foundation reinforcement in civil and geotechnical engineering.

[0083] Understandably, the three types of Bacillus described above in this invention can be used to prepare a formulation for solidifying granite residual soil.

[0084] In some embodiments, the formulation contains one or more of Bacillus aquatilis, Bacillus argentis, and Bacillus stropharia.

[0085] One or more of the above-mentioned strains can be formulated into a preparation for easy use. When using it, the appropriate amount of preparation can be added according to the volume of the residual soil in the granite.

[0086] The present invention will be further described below with reference to specific embodiments and comparative examples, but these should not be construed as limiting the scope of protection of the present invention.

[0087] Example 1:

[0088] (1) Screening and identification of strains

[0089] Collected sea sand samples (near the South China Sea) were enriched and cultured at 37℃ and 5M high-concentration urea for 24 hours to kill the vegetative cells of various microorganisms that could not tolerate or utilize high-concentration urea. The treated culture medium was then serially diluted, plated on urease screening plates, and incubated at 37℃. Strains that turned the culture medium red were selected, and single colonies were isolated by streaking, yielding three urease-producing microorganisms: *Bacillus aquimaris* H216, *Bacillus aryabhattai* H961, and *Terribacillus saccharophilus* H986. These three isolated strains possess urea-degrading enzymes, which decompose urea to produce large amounts of ammonia, making the culture medium alkaline and turning it red.

[0090] The above-mentioned marine Bacillus, Arne Bacillus, and Soil Bacillus all have rod-shaped cells, spores, no capsules, and are Gram-positive. Figure 1Electron micrograph of Bacillus aquimaris H216; Figure 2 Electron micrograph of Bacillus aryabhattai H961; Figure 3 Electron micrograph of Terribacillus saccharophilus H986.

[0091] On NH4-YE medium, the colonies are round, moist and smooth, with neat edges, and the size of the colonies is 1 mm to 2 mm. The colonies are pale yellow. Furthermore, the above three isolated strains can grow in a medium temperature range of 4℃ to 37℃ and a pH range of 7.0 to 9.5.

[0092] The three isolated bacteria were further identified by 16S rDNA sequencing. The 16S DNA sequence of Bacillus aquaticus is shown in SEQ ID NO.1; the 16S DNA sequence of Bacillus argentea is shown in SEQ ID NO.2; and the 16S DNA sequence of Bacillus sphaeroides is shown in SEQ ID NO.3.

[0093] SEQ ID NO.1:

[0094]

[0095] SEQ ID NO.2:

[0096]

[0097] SEQ ID NO.3:

[0098]

[0099] The aforementioned marine Bacillus aquimaris H216 was deposited on July 4, 2019, at the China General Microbiological Culture Collection Center (address: No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing, 100101, China), with accession number CGMCC No. 18068.

[0100] The aforementioned Bacillus aryabhattai H961 was deposited on July 4, 2019, at the China General Microbiological Culture Collection Center (address: No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing, 100101, China), with accession number CGMCC No. 18069.

[0101] The aforementioned soil spore bacterium Terribacillus saccharophilus H986 was deposited on July 4, 2019, at the China General Microbiological Culture Collection Center (address: No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing, 100101, China), with accession number CGMCC No. 18070.

[0102] (2) Strain culture

[0103] Prepare NH4-YE medium and high-salt medium according to the following formulas:

[0104] NH4-YE medium: Yeast extract 20g / L, ammonium sulfate 10g / L, pH adjusted to 7.5-9.0.

[0105] High-salt culture medium: Yeast extract 20g / L, ammonium chloride 10g / L, pH adjusted to 7.5-9.0.

[0106] Take 100 mL of NH4-YE medium or high-salt medium, transfer it to a 500 mL culture flask, and sterilize it at high temperature for later use. Pick single colonies of *Bacillus aquimaris* H216, *Bacillus aryabhattai* H961, and *Terribacillus saccharophilus* H986 from the agar plates, inoculate them into 500 mL culture flasks, and incubate them at 30℃ and 200 rpm for 16 h. Collect the bacterial solution for later use; and determine the biomass (OD) of the bacterial solution. 600 ) and urease activity.

[0107] Figure 4The OD values ​​of the three strains after culturing in NH4-YE medium and high-salt medium, respectively. 600 Values. As shown in the figure, compared with the other two strains, the bacterial concentration of Bacillus aryabhattai H961 is relatively higher; and the growth status of all three strains in high-salt medium is slightly better than that in NH4-YE medium.

[0108] Figure 5 The figure shows the urease activity of three strains after culturing in NH4-YE medium and high-salt medium, respectively. As can be seen from the figure, regardless of the medium used, the urease activity of *Bacillus aquimaris* H216 and *Terribacillus saccharophilus* H986 was higher than that of *Bacillus aryabhattai* H961; furthermore, the urease activity of all three strains after culturing in NH4-YE medium was higher than that in high-salt medium.

[0109] Figure 6 The figure shows the urease activity of three strains after being cultured in high-salt media at different temperatures. As can be seen from the figure, the three strains have a very wide growth temperature range, surviving and growing at temperatures from -4℃ to 80℃ while exhibiting high urease activity; among them, the strains cultured in the range of 28℃ to 50℃ showed significantly higher urease activity.

[0110] Figure 7 The figure shows the urease activity of three strains after culturing in high-salt media under different pH conditions. As can be seen from the figure, all three microorganisms exhibit some alkali tolerance, surviving and growing with high urease activity within a pH range of 7.0–10.0. Furthermore, under different pH conditions, the urease activity of *Terribacillus saccharophilus* H986 was higher than that of the other two strains.

[0111] (3) Preparation of solidified sand columns

[0112] The residual soil from the granite was sampled in Zhaoqing City, Guangdong Province, and its particle size distribution is as follows: Figure 8 As shown, approximately 95% of the granite residual soil particles have a particle size between 0.1 mm and 0.4 mm; XRD analysis indicates that the main component of this granite residual soil sample is quartz.

[0113] To control particle size, the residual soil from the granite was sieved, and sand particles with a diameter of 0.1 mm to 0.4 mm were collected as samples for the next step.

[0114] 100g of dry granite residual soil was filled into a sterile model column with a volume of 50mL, a height of 110mm, and an inner diameter of 30mm to create a sand column to be solidified. To prevent clogging of the grouting port, double-layer gauze filters were placed at both ends of the sand column to be solidified.

[0115] (4) Grouting

[0116] The distributed grouting method was used, sequentially injecting bacterial solution, fixative (0.05M CaCl2), and cementing solution (a mixture of 0.5M CaCl2 and 0.5M urea). Injection was performed using a syringe, with the upper end of the syringe sealed with a rubber stopper with a three-way valve. Two layers of coarse sand were used as filters at both ends of the syringe to prevent clogging during calcium carbonate precipitation.

[0117] First, use a peristaltic pump to pump 150 mL of deionized water at a rate of 10 rpm (approximately 1 mL / min) to saturate the sand column as much as possible. Then, inject 40 mL of the three bacterial solutions collected in step (2) into each of the three sand columns (each group has 3 replicates) at a rate of 0.5 mL / min. Subsequently, inject 50 mL of 0.05 M CaCl2 solution into each sand column at a rate of 0.5 mL / min. Finally, inject 150 mL of cementing solution into each sand column at a rate of 0.1 mL / min to form a microbial-calcium carbonate-sand particle solid in the sand-solution system, thereby enhancing the adhesion and strength of the sand particles.

[0118] (5) Results Analysis

[0119] XRD analysis of the white precipitate in each sand column revealed that it was calcium carbonate. Further electron microscopy analysis of the precipitate yielded the following results: Figures 9-11 As shown ( Figure 9 Perfusion of Bacillus aquimaris H216; Figure 10 Perfusion of Bacillus aryabhattai H961; Figure 11 (The solution was injected with *Terribacillus saccharophilus* H986). After injection with the bacterial solution of the above three strains, spherical and hexahedral calcium carbonate crystals were clearly visible between the sand grains.

[0120] Furthermore, the obtained sand columns were demolded, and all sand columns were found to be bonded and formed with a certain strength. Uniaxial compression tests were then performed on all sand columns. The sand column specimens were cylinders with a diameter of 50 mm and a height of 100 mm. The parallelism deviation between the two end faces of the specimen should not exceed 0.1 mm. The specimens were placed in the center of the pressure plate of the press, and the pressure plate was adjusted to ensure uniform force on the specimens. The specimens were loaded at a loading rate of 0.5 MPa / s to 0.8 MPa / s until failure. Each group contained no fewer than three specimens. The results are as follows: Figure 12 As shown: the uniaxial compressive strength of sand columns infused with Bacillus aryabhattai H961 is approximately 0.6 MPa; the uniaxial compressive strength of sand columns infused with Bacillus aquimaris H216 is approximately 0.4 MPa; and the uniaxial compressive strength of sand columns infused with Terribacillus saccharophilus H986 is approximately 0.2 MPa.

[0121] The above results show that all three Bacillus strains of the present invention can bind loose sand grains together, thereby improving the compressive strength of granite residual soil to a certain extent. Among them, Bacillus aquimaris H216 (seawater Bacillus) and Terribacillus saccharophilus H986 (soil Bacillus) have a relatively better effect on solidifying granite residual soil.

[0122] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0123] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for consolidating residual soil from granite, characterized in that, Includes the following steps: Provide Bacillus; and The Bacillus, fixative, and cementing solution were sequentially injected into the residual soil of the granite. The Bacillus is selected from Bacillus marineus, and the preservation number of Bacillus marineus is CGMCC No.18068.

2. The method for consolidating residual granite soil according to claim 1, characterized in that, After the step of providing Bacillus and before infusing the Bacillus, the method further includes: Single colonies of Bacillus were inoculated into the fermentation medium and cultured at 25℃~37℃ and 150rpm~250rpm for 12h~60h.

3. The method for consolidating residual granite soil according to claim 2, characterized in that, The fermentation medium is NH4-YE medium or high-salt medium.

4. The method for consolidating residual granite soil according to any one of claims 1 to 3, characterized in that, The fixative includes 0.04M~0.06M CaCl2.

5. The method for consolidating residual granite soil according to any one of claims 1 to 3, characterized in that, The cementing solution contains 0.4M~0.6M CaCl2 and 0.4M~0.6M urea.

6. The method for consolidating residual granite soil according to any one of claims 1 to 3, characterized in that, The ratio of the Bacillus bacterial solution, the fixative and the cementing solution is (40mL~160mL):50mL:(140mL~160mL).

7. The method for consolidating residual granite soil according to any one of claims 1 to 3, characterized in that, The slurry filling rate of the Bacillus bacterial solution is 0.05 mL / min to 1.00 mL / min; and / or The grouting rate of the fixative is 0.05 mL / min to 1.00 mL / min; and / or The grouting rate of the cementing solution is 0.05 mL / min to 0.15 mL / min.

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