CN113445490B - Method for uniformly solidifying soft clay by microorganisms - Google Patents
Method for uniformly solidifying soft clay by microorganisms Download PDFInfo
- Publication number
- CN113445490B CN113445490B CN202110730691.0A CN202110730691A CN113445490B CN 113445490 B CN113445490 B CN 113445490B CN 202110730691 A CN202110730691 A CN 202110730691A CN 113445490 B CN113445490 B CN 113445490B
- Authority
- CN
- China
- Prior art keywords
- soil
- bacterial suspension
- stirring
- fermentation
- liquid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
- E02D3/12—Consolidating by placing solidifying or pore-filling substances in the soil
-
- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
- C12N1/00—Microorganisms, e.g. protozoa; Compositions thereof; Processes of propagating, maintaining or preserving microorganisms or compositions thereof; Processes of preparing or isolating a composition containing a microorganism; Culture media therefor
- C12N1/02—Separating microorganisms from their culture media
-
- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
- C12N1/00—Microorganisms, e.g. protozoa; Compositions thereof; Processes of propagating, maintaining or preserving microorganisms or compositions thereof; Processes of preparing or isolating a composition containing a microorganism; Culture media therefor
- C12N1/20—Bacteria; Culture media therefor
Landscapes
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Zoology (AREA)
- Wood Science & Technology (AREA)
- Genetics & Genomics (AREA)
- Bioinformatics & Cheminformatics (AREA)
- Biotechnology (AREA)
- General Engineering & Computer Science (AREA)
- Biomedical Technology (AREA)
- Structural Engineering (AREA)
- General Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Tropical Medicine & Parasitology (AREA)
- Virology (AREA)
- Biochemistry (AREA)
- Microbiology (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Civil Engineering (AREA)
- Soil Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Mining & Mineral Resources (AREA)
- Paleontology (AREA)
- Agronomy & Crop Science (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
A method for uniformly solidifying soft clay by microorganisms has the advantages of simple process, high material utilization rate and no pollutant generation during solidification, and is characterized by comprising the following steps: a. inoculating activated Bacillus kefir (Bacillus cohnii) strain into a fermentation culture medium, and performing shake culture at 30 ℃ for 48h to obtain fermentation liquor; b. separating the fermentation liquor by a centrifugal machine, removing clear liquid, collecting thalli, and transferring the thalli into nutrient salt solution with the same volume as the clear liquid to obtain bacterial suspension; c. rapidly adding calcium hydroxide into the bacterial suspension to prepare a biological cementing solution 1, immediately stirring the biological cementing solution 1 and the soil 3 to be reinforced uniformly by using a deep layer stirrer 2, and leveling the field after stirring; d. monitoring points are arranged in the field, a load test is carried out every 5 days to obtain a real-time foundation bearing capacity value, and soil solidification is finished when the foundation bearing capacity is larger than 200 kPa.
Description
Technical Field
The invention relates to a method for uniformly solidifying soft clay by microorganisms, belonging to the technical field of foundation treatment.
Background
The microbial soil-fixing technology is a novel foundation-reinforcing technology which utilizes the metabolic activity of microbes to induce and form calcium carbonate crystals, and glues loose soil particles into a whole to realize soil solidification. The soil conditioner has the advantages of environmental friendliness, small disturbance to soil and the like, and is widely concerned in recent years. At present, microorganism soil fixation is mostly carried out by adopting a sectional grouting mode, namely, a grouting device is used for repeatedly and alternately injecting bacterial liquid and cementing solution into an area to be reinforced until the soil body reaches the preset strength. Due to the heterogeneity of the space distribution and mineralization reaction of bacteria, the problem of uneven reinforcement strength and difficult control of reinforcement range generally exists when soil reinforcement is carried out by adopting a sectional grouting mode, calcium carbonate crystals can be preferentially gathered near a grouting opening, so that the strength of soil bodies at the near end and the far end of the grouting opening is obviously different, the problem that the smaller the soil particle size is, the more prominent the problem is, and the reinforcement heterogeneity becomes a main factor for restricting the application of the technical engineering.
Patents with publication numbers CN105714765A and CN108049409A respectively control the biological mineralization rate by reducing the temperature of the living environment of bacteria and adding urease inhibitor, so as to prevent calcium carbonate cement formed after the bacteria solution and the cementing solution are mixed and injected into the soil from blocking the grouting opening, although reinforcement nonuniformity caused by a sectional grouting manner is overcome to a certain extent, the effective reinforcement range of single-hole grouting is enlarged, both the two need to be grouted for multiple times to enable the soil to reach the predetermined strength, the material utilization rate is low, the soil is made alkaline in the reinforcement process and a large amount of ammonia gas is generated to easily pollute the environment; the patent with publication number CN108192623A proposes that a mixing machine is used for mixing bacteria with a soil body to be reinforced, and then nutrient solution and cementing solution are repeatedly injected, although the uniformity of microorganism soil fixation is improved by solving the problem of nonuniform bacteria space distribution, the soil fixation method has more processes, the soil body can reach the preset strength only by multiple times of grouting, the material utilization rate is low, and the construction period is long; the patent of publication No. CN105970913A proposes that the space distribution of microorganisms and nutrient salt ions in soil is changed by an electroosmosis method, the uniformity of microorganism soil fixation is improved by controlling the mineralization reaction process, and the adverse condition that the grouting effect is influenced by the large deposition of calcium carbonate near a grouting opening can be improved.
Disclosure of Invention
The technical problem is as follows: in summary, the existing schemes for improving the unevenness of microorganism soil fixation all have certain disadvantages, no matter the activity of urease is inhibited or bacteria and soil are uniformly mixed and grouted, the reinforcement body can not reach the preset strength through single solidification, the material utilization rate is low, the construction period is long, and the environment is easily polluted. The soft clay is widely distributed in coastal, lake and river areas of China, has the characteristics of high water content, high compressibility, low shear strength and the like, and has poor engineering properties. In recent years, the shortage of land resources and the development of society have required a large number of infrastructure projects to be built or expanded on soft clay foundations, and in order to ensure the safe and normal use of buildings, such special foundations must be treated. Due to the hydraulic permeability coefficient of the soft clay, the compatibility of the soil particle size and pore throat size with the individual size of the microorganism, the problems of low reinforcement strength, poor reinforcement uniformity and the like generally exist in the prior art of solidifying the soft clay by adopting segmented microorganism grouting, and the application of the microorganism soil solidifying technology in the foundation treatment of the soft clay is severely limited by the current situation. The invention aims to provide a method for uniformly solidifying soft clay by microorganisms, which realizes uniform solidification of soil to be reinforced and a mixed solution containing bacteria, calcium lactate, calcium hydroxide and the like through one-time mixing by controlling a biomineralization reaction process, does not generate pollutants during solidification, and provides a new way for treating soft clay foundations.
In order to achieve the purpose of the invention, the invention discloses a method for uniformly solidifying soft clay by microorganisms, which is characterized by comprising the following steps:
a. inoculating activated Bacillus cohnii (Bacillus cohnii) strain into a fermentation medium, and performing shake culture at 30 ℃ for 48h to obtain a fermentation liquid, wherein the fermentation medium with the pH of 7.0,1L comprises 5g of beef extract, 10g of peptone and 5g of sodium chloride;
b. separating the fermentation liquor by a centrifugal machine, removing clear liquid, collecting thalli, and transferring the thalli into nutrient salt solution with the same volume as the clear liquid to obtain bacterial suspension;
c. rapidly adding calcium hydroxide into the bacterial suspension to prepare a biological cementing solution 1, immediately and uniformly stirring the biological cementing solution 1 and the soil 3 to be reinforced by using a deep layer stirrer 2, wherein the ratio of the volume of the biological cementing solution 1 to the pore volume of the soil 3 to be reinforced is 0.75-0.90, and leveling the field after stirring;
d. and arranging monitoring points in the field, carrying out a load test every 5 days to obtain a real-time foundation bearing capacity value, and finishing soil solidification when the foundation bearing capacity is greater than 200 kPa.
The method for uniformly solidifying the soft clay by the microorganisms is characterized in that the OD value of the fermentation liquor in the step a is 1.8.
The method for uniformly solidifying the soft clay by the microorganisms is characterized in that in the step b, the pH of a nutrient salt solution is 6.0, the dissolved oxygen concentration is 15mg/L, the preparation temperature is 30 ℃, and 1L of the nutrient salt solution contains 10g of beef extract, 20g of peptone, 8g of sodium chloride and 462-616 g of calcium lactate.
The method for uniformly solidifying the soft clay by the microorganisms is characterized in that the adding amount of calcium hydroxide in 1L of the bacterial suspension in the step c is 111-148 g, and the bacterial suspension is not stirred after the calcium hydroxide is added.
The invention has the beneficial effects that:
(1) Compared with the soil consolidation method of repeatedly injecting bacterial liquid and cementing solution into the region to be consolidated, the invention mixes the soil body with bacteria, calcium lactate, calcium hydroxide and the like to prepare biological cementing solution, and then the biological cementing solution is mixed and solidified at one time, thereby simplifying the construction process and reducing the construction cost; (2) The mixing mode can make the bacterium distribute relatively evenly in the stratum, can utilize metabolism activity to decompose calcium lactate into pollution-free calcium carbonate, carbon dioxide and water gradually after the bacterium adsorbs the soil granule, the calcium carbonate that is formed by calcium lactate decomposition directly has carried out preliminary even solidification to the soil body, and the carbon dioxide that generates then can further react with the calcium hydroxide in the soil body and generate calcium carbonate and realize soil body secondary cure, material utilization is high, and along with the continuous consumption of calcium hydroxide, the soil environment is changed into near neutral from strong basicity gradually, soil alkalization has been avoided.
Drawings
FIG. 1 schematic diagram of mixing of soil to be consolidated with biological cement
Reference numerals: 1-biological cementing liquid; 2-deep layer stirrer; 3-the soil to be reinforced.
Detailed Description
Example 1
In this example, a method of uniformly solidifying soft clay by microorganisms is used for reinforcing a muddy clay foundation, the water content of the soil to be reinforced is 49.32%, the natural pore ratio is 1.34, and the bearing capacity is 35kPa, the method comprises the following steps:
a. inoculating activated Bacillus cohnii (Bacillus cohnii) strain into a fermentation culture medium with the pH of 7.0, and performing shake culture at the temperature of 30 ℃ for 48 hours to obtain a fermentation liquid, wherein 1L of the fermentation culture medium contains 5g of beef extract, 10g of peptone and 5g of sodium chloride, and the OD value of the fermentation liquid is 1.8;
b. separating the fermentation liquor by a centrifugal machine, removing clear liquid, collecting thalli, and transferring the thalli into nutrient salt solution which has the same volume with the clear liquid to obtain bacterial suspension, wherein the preparation temperature of the nutrient salt solution is 30 ℃, the dissolved oxygen concentration is 15mg/L, and the pH is controlled to be 6.0.1L, and the nutrient salt solution contains 10g of beef extract, 20g of peptone, 8g of sodium chloride and 616g of calcium lactate;
c. rapidly adding calcium hydroxide into the bacterial suspension to prepare a biological cementing liquid 1, wherein the adding amount of the calcium hydroxide in 1L of the bacterial suspension is 148g, stirring the bacterial suspension after the calcium hydroxide is added, then immediately stirring the biological cementing liquid 1 and a soil layer 3 to be reinforced by using a deep layer stirrer 2, wherein the ratio of the volume of the added biological cementing liquid 1 to the pore volume of the soil 3 to be reinforced is 0.75, and leveling the ground after stirring;
d. monitoring points are arranged in the field, a load test is carried out every 5 days to obtain a real-time foundation bearing capacity value, and when the foundation bearing capacity of the field reaches 205kPa after 30 days of reinforcement treatment, soil solidification is immediately finished.
Example 2
In this example, a method of uniformly solidifying soft clay by microorganisms is used for reinforcing a silty clay foundation, the water content of soil to be reinforced is 43.50%, the natural porosity ratio is 1.25, and the bearing capacity is 65kPa, the method comprises the following steps:
a. inoculating activated Bacillus kefir (Bacillus cohnii) strain into a fermentation culture medium with the pH value of 7.0, and performing shake culture at the temperature of 30 ℃ for 48 hours to prepare a fermentation liquid, wherein 1L of the fermentation culture medium comprises 5g of beef extract, 10g of peptone and 5g of sodium chloride, and the OD value of the fermentation liquid is 1.8;
b. separating the fermentation liquor by a centrifugal machine, removing clear liquid, collecting thalli, and transferring the thalli into nutrient salt solution with the same volume as the clear liquid to obtain bacterial suspension, wherein the preparation temperature of the nutrient salt solution is 30 ℃, the dissolved oxygen concentration is 15mg/L, and the pH is controlled to be 6.0.1L, and the nutrient salt solution contains 10g of beef extract, 20g of peptone, 8g of sodium chloride and 462g of calcium lactate;
c. rapidly adding calcium hydroxide into the bacterial suspension to prepare a biological cementing solution 1, wherein the adding amount of the calcium hydroxide in 1L of the bacterial suspension is 111g, stirring the bacterial suspension after adding the calcium hydroxide, then immediately stirring the biological cementing solution 1 and the soil 3 to be reinforced by adopting a deep layer stirrer 2, wherein the ratio of the volume of the added biological cementing solution 1 to the pore volume of the soil 3 to be reinforced is 0.90, and leveling the field after stirring;
d. monitoring points are arranged in the field, a load test is carried out every 5 days to obtain a real-time foundation bearing capacity value, and when the foundation bearing capacity of the field reaches 223kPa after 25 days of reinforcement treatment, soil solidification is immediately finished.
Claims (1)
1. A method for uniformly solidifying soft clay by microorganisms is characterized by comprising the following steps:
a. activated bacillus kefir: (Bacillus cohnii) Inoculating the strain into a fermentation medium, and performing shake culture at 30 ℃ for 48h to obtain a fermentation liquid, wherein the fermentation medium with the pH of 7.0 and the pH of 1L comprises 5g of beef extract, 10g of peptone and 5g of sodium chloride;
b. separating the fermentation liquor by a centrifugal machine, removing clear liquid, collecting thalli, and transferring the thalli into nutrient salt solution with the same volume as the clear liquid to obtain bacterial suspension;
c. rapidly adding calcium hydroxide into the bacterial suspension to prepare a biological cementing liquid (1), immediately and uniformly stirring the biological cementing liquid (1) and the soil (3) to be reinforced by adopting a deep-layer stirrer (2), wherein the ratio of the volume of the biological cementing liquid (1) to the pore volume of the soil (3) to be reinforced is 0.75-0.90, and leveling the field after stirring;
d. arranging monitoring points in the field, carrying out a load test every 5 days to obtain a real-time foundation bearing capacity value, and finishing soil solidification when the foundation bearing capacity is greater than 200 kPa;
the OD value of the fermentation liquor in the step a is 1.8;
in the step b, the pH of the nutrient salt solution is 6.0, the dissolved oxygen concentration is 15mg/L, the preparation temperature is 30 ℃, and 1L of the nutrient salt solution contains 10g of beef extract, 20g of peptone, 8g of sodium chloride and 462 to 616g of calcium lactate;
and c, adding the calcium hydroxide into the 1L of the bacterial suspension in the step c in a dosage of 111 to 148g, and not stirring the bacterial suspension after the calcium hydroxide is added.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110730691.0A CN113445490B (en) | 2021-06-29 | 2021-06-29 | Method for uniformly solidifying soft clay by microorganisms |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110730691.0A CN113445490B (en) | 2021-06-29 | 2021-06-29 | Method for uniformly solidifying soft clay by microorganisms |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113445490A CN113445490A (en) | 2021-09-28 |
| CN113445490B true CN113445490B (en) | 2022-10-25 |
Family
ID=77814167
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110730691.0A Active CN113445490B (en) | 2021-06-29 | 2021-06-29 | Method for uniformly solidifying soft clay by microorganisms |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113445490B (en) |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109518678A (en) * | 2018-11-02 | 2019-03-26 | 东南大学 | A kind of method of plant mucilage-microbial association soil mass consolidation |
| CN109900880A (en) * | 2019-03-25 | 2019-06-18 | 贵州大学 | A kind of MICP test method using immobilized microorganism technique |
| CN110130318A (en) * | 2019-05-24 | 2019-08-16 | 南京林业大学 | A kind of construction method of microorganism mixing-filling stake |
| CN111893988A (en) * | 2020-08-31 | 2020-11-06 | 武汉理工大学 | Ecological improvement method for microorganism-induced silty-fine sand consolidated soft soil roadbed |
-
2021
- 2021-06-29 CN CN202110730691.0A patent/CN113445490B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN113445490A (en) | 2021-09-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN105714765B (en) | A kind of solid indigenous method of microorganism low-temperature slip casting | |
| CN108761044B (en) | Test device and method for microorganism-induced calcium carbonate precipitation solidification sand under negative pressure environment | |
| CN108220196B (en) | Method for treating petroleum-polluted clay foundation by using microbial composite flora | |
| JP6489569B1 (en) | Ground improvement method | |
| CN105297705A (en) | Biological sandstone preparation method and device based on MICP (Microbial Induced Carbonate Precipitation) technology | |
| JP5140879B1 (en) | Ground improvement method | |
| CN110438974B (en) | Microbial solidification kit and method for in-situ solidification of calcareous sand | |
| JP6531902B2 (en) | Heavy metal insolubilizing composition and method for repairing heavy metal contaminated soil | |
| CN110144876B (en) | Microorganism soil fixation method for controlling cementation rate | |
| CN103773376A (en) | Method for solidifying loose coral sand by using microorganisms | |
| CN110813979A (en) | Method for realizing harmless treatment of cyanide tailings by utilizing microbial technology | |
| CN114657971B (en) | Microbial microcapsule, preparation method thereof and application of microbial microcapsule in curing soft soil foundation | |
| Kadhim et al. | Review of the factors that influence on the microbial induced calcite precipitation | |
| Muthukkumaran et al. | Durability of microbially induced calcite precipitation (MICP) treated cohesionless soils | |
| Tang et al. | Effect of cementation on calcium carbonate precipitation of loose sand resulting from microbial treatment | |
| CN113445490B (en) | Method for uniformly solidifying soft clay by microorganisms | |
| CN110510849B (en) | In-situ treatment and restoration method for polluted bottom mud | |
| CN114214249B (en) | Double-fungus microbial inoculum and application thereof in restoration of desertification soil | |
| CN110820454A (en) | Water-permeable soil-based curing liquid and application thereof in preparation of water-permeable soil-based | |
| CN115679939A (en) | Method for reinforcing soil foundation by combining pretreatment with microbial mineralization technology | |
| CN112122331B (en) | Method for solidifying and stabilizing heavy metal polluted soil | |
| Asgharzadeh et al. | Optimizing the use of Sporosarcina pasteurii bacteria for the stiffening of sand | |
| Cui et al. | Review on research progress of MICP technology | |
| CN114482087A (en) | Method for solidifying side slope by microorganism mineralization filling-magnesia carbonization guniting | |
| CN111334309A (en) | Biological reinforcement method using magnesium additive and application thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |