Method for improving microbial cemented sand

A technology of microbial glue and sand, which is applied in the field of geotechnical engineering, can solve problems such as hidden safety hazards and loss of strength, and achieve the effects of improving toughness, increasing toughness, increasing unconfined compressive strength and residual strength

Active Publication Date: 2020-04-07
ZUNYI NORMAL COLLEGE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the mutual exclusion of strength and toughness has always been a challenging issue for geotechnical engineering materials
Although the strength of sand reinforced by microbial cementation can reach a high level, it is largely a typical brittle material, that is, the strength is lost instantly after failure, and there are certain hidden dangers in terms of safety.

Method used

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  • Method for improving microbial cemented sand

Examples

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Effect test

Embodiment 1

[0036] A kind of method of improving microbial cemented sand of the present embodiment comprises the following steps:

[0037] (1) Select the appropriate chemo-heterotrophic Gram-positive bacteria, prepare the corresponding medium to cultivate them, and then test the OD of the bacterial solution 600 Value and activity value, store the bacterial solution in a low temperature environment, and activate it regularly to maintain its activity;

[0038] (2) configure the cementing fluid matched with the selected chemo-heterotrophic Gram-positive bacteria;

[0039] (3) preparing soil by mixing cohesive soil, sand and stone in a weight ratio of 2:3:5;

[0040] (4) In parts by weight, mix 2 to 7 parts of sulfuric acid amide, 3 to 8 parts of triisopropanolamine, 10 to 20 parts of talcum powder, and 3 to 10 parts of carbolic acid, and adjust the pH value of the resulting mixture to make it The pH value is 7-9, and the modifying agent is obtained and set aside;

[0041] (5) Add the prep...

Embodiment 2

[0046] In this embodiment, on the basis of the foregoing embodiments, the microorganisms selected for use are further limited, and the chemoheterotrophic Gram-positive bacteria selected in the step (1) is Bacillus sarcina. The bacterial strain was purchased from the American Type Culture Collection, numbered ATCC11859, and the bacterium was a chemoheterotrophic Gram-positive bacterium. The individuals of Bacillus sarcina are oval, with a length of about 2-3 μm. This bacterium is currently the most commonly used bacterium for MICP in the field of geotechnical engineering, and its activity of secreting urease is relatively strong, which is representative to a certain extent. Other parts of this embodiment are the same as those of the foregoing embodiment, and will not be repeated here.

Embodiment 3

[0048] On the basis of the above-mentioned examples, the present embodiment further defines the medium components for cultivating microorganisms, the medium components configured in the step (1), in parts by weight, are 20 parts of yeast extract , 10 parts of ammonium sulfate, and 16 parts of Trisbase. The specific process of culturing microorganisms is as follows:

[0049] Use a constant temperature shaker incubator to carry out aerobic culture of bacteria at 30°C and 120rpm for 24 hours, and then use a microplate reader to measure the OD of the bacterial solution 600 (per unit OD 600 The value corresponds to about 108 bacteria) and the value is about 1.10. Using a conductivity meter to measure its activity is about 2.79mMureahydrolysed min -1 ·OD -1 . The strains were stored in a refrigerator at 4°C and activated regularly to maintain their activity. Other parts of this embodiment are the same as those of the foregoing embodiment, and will not be repeated here.

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Abstract

The invention discloses a method for improving microbial cemented sand. The method comprises the following steps that 1), bacteria are cultured, then the OD 600 value and the activity value of the bacterial liquid are tested, and the bacterial liquid is stored; 2), a cementing solution is prepared; 3), a soil body is prepared; 4), a modifier is prepared; 5), the modifier is added to the soil body,and the weight ratio of the modifier to the soil body is 1:1,000; 6) then, the bacterial liquid is added, the weight ratio of the bacterial liquid to the soil body is 100:1; 7), the cementing solution is added, wherein the weight ratio of the cementing solution to the soil body is 3:10; and 8), finally, an allicin aqueous solution with the mass fraction being 2.5% is added, and the weight ratio of the allicin aqueous solution to the soil body is 1:1,000. By the adoption of the method for improving the microbial cemented sand, the unconfined compressive strength and the residual strength of the sand soil can be remarkably improved, in particular, the defects of the original brittleness of the microbial cemented sand can be improved, the toughness in the damage process is increased, the positive effect is achieved for improving the safety and stability of the engineering structure, and the method is suitable for wide application and popularization.

Description

technical field [0001] The invention relates to the technical field of geotechnical engineering, in particular to a method for improving microbial cementation of sandy soil. Background technique [0002] Microbe-induced calcium carbonate deposition (MICP) technology is a new soil improvement and reinforcement technology developed in recent years. This technology is based on the biochemical mineralization process that occurs inside the soil in nature - the urease secreted by microorganisms hydrolyzes urea and combines with calcium ions to generate calcium carbonate, which cements the soil particles, thereby improving the physical and mechanical properties of the soil. Purpose. Due to the advantages of energy saving and emission reduction, eco-environmental protection, economical efficiency, and little soil disturbance, this technology has attracted widespread attention from scholars at home and abroad, and a lot of research has been carried out on the engineering properties ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E02D3/12C12N1/20C12R1/01
CPCC12N1/20E02D3/12
Inventor 袁余洋
Owner ZUNYI NORMAL COLLEGE
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