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Method for improving mechanical properties of calcium sand through fiber reinforced and microbial curing

A fiber-reinforced, microbial technology, applied in the geotechnical-biological-chemical-interdisciplinary field, can solve the problems of poor ductility and brittle failure of the solidified body, reduce brittleness, improve unconfined compressive strength and resistance Tensile strength, the effect of increasing ductility

Inactive Publication Date: 2020-01-14
WUHAN UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Microbial solidification technology has also made many achievements in the consolidation of loose calcareous sand, and the strength of the obtained calcareous sand solidification body reaches several MPa; Poor ductility, prone to brittle failure

Method used

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  • Method for improving mechanical properties of calcium sand through fiber reinforced and microbial curing
  • Method for improving mechanical properties of calcium sand through fiber reinforced and microbial curing
  • Method for improving mechanical properties of calcium sand through fiber reinforced and microbial curing

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] In practical application: the 8mm long monofilament chopped basalt fiber and calcareous sand are mixed according to the weight ratio of 1% (the percentage of fiber accounts for sand weight), for example, the quality m of calcareous sand is 27.6g, and the fiber is 0.276g, The mixture is 27.876 grams in total. Stir with a mixer until the fibers are evenly distributed, then fill in 10mm, stop and tamp, then take 8mm long monofilament chopped basalt fibers and mix them with calcareous sand at a ratio of 1%, and stir until the fibers are evenly distributed , stop and tamp after filling 10mm, repeat 10 times until the filling is complete.

[0027] The lyophilized powder of Bacillus pasteurianum was adjusted to pH 7.3 by adjusting the pH to 7.3, and the obtained bacterial liquid was stored in a refrigerator at 4°C and used within 7 days.

[0028] Into the mixture of loose fibers and sand, use a peristaltic pump to pass the bacterial solution from the upper end and let it stand...

Embodiment 2

[0039] Sample preparation

[0040]Take a sample mold with a height of 165mm and a diameter of 50mm, cut it evenly into three pieces, then tighten it with a throat hoop, and cover the inside of the mold with the latex film used in the triaxial test to prevent water leakage; chop the monofilament Basalt fibers (see Table 1 for performance parameters) were mixed into the sand according to the lengths of 4mm, 8mm, 12mm and 18mm, and the fiber contents were 0%, 0.4%, 0.8%, 1% and 1.2% (the percentage of fiber to sand weight) In the calcareous sand, use the method of manual stirring until the fibers are evenly distributed, stop and tamp after filling 10mm, then take new fibers and sand, mix and fill 10mm, stop and tamp, fill 10 times in total, in the sand samples to be solidified The upper and lower ends are respectively equipped with 20mm thick 2-5mm coarse gravel as a barrier layer.

[0041] Table 2 Performance parameters of basalt fiber

[0042]

[0043] A total of 17 groups...

Embodiment 3

[0047] The Activation Culture and Preservation of Bacillus Pasteurella

[0048] The culture medium was prepared, the composition of the culture medium was shown in Table 4, and the solvent was distilled water.

[0049] Table 4 Medium composition

[0050] Element tryptone Peptone Sodium chloride urea content 15g / L 5g / L 5g / L 20g / L

[0051] Dissolve the lyophilized powder of Bacillus pasteurianus (ATCC 11859) in deionized water, then inoculate it into the solid slant medium prepared according to Table 4, cultivate it in a constant temperature incubator at 30°C for 24 hours, and prepare it into a glycerol tube for storage; The glycerol tube was thawed in a water bath and poured into the liquid medium, and then the liquid medium was placed in a constant temperature gyratory shaking incubator with a rotation speed of 130rmp / min and a temperature of 30°C until OD 600 = 1.205, the bacterial solution obtained by adjusting the pH to 7.3 was stored in...

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Abstract

The invention provides a method for improving mechanical properties of calcium sand through fiber reinforced and microbial curing. The method comprises the following steps that coarse gravels are loaded at the bottom of a mold as a spacing layer, fibers and calcium sand are mixed and stirred evenly and are filled in a sample mold and tamped, then monofilament short-cut basalt fibers with the samelength are mixed with calcium sand according to the same proportion and then stirred evenly and filled in the sample mold and tamped, repeated for a plurality of times until the filling is finished, and laying up an isolating flow layer. The bacteria liquid is obtained through procedures applied to freeze-dried powder of bacillus pasteurii such as slope activation culture, glycerol tube retention,expansion culture bacillus pasteurii freeze-dried powder. In a mixture of loose fibers and sand, a peristaltic pump is used for firstly introducing bacterial liquid from the upper end of the mold andthen standing, after the bacterial liquid completely seeps, the mixed solution of urea and calcium chloride is introduced from the lower end of the mold, after the mixed solution is completely seeping out, standing is carried out for 2 hours, and repeated curing is carried out. According to the method, the unconfined compressive strength and the tensile strength of the calcium sand are improved,and the defect of brittle failure of the solidified body is solved.

Description

technical field [0001] The invention belongs to the field of geotechnical-biology-chemistry-interdisciplinary, and particularly relates to a method for improving the mechanical properties of calcareous sand through fiber-reinforced microbial solidification. Background technique [0002] Calcareous sand is a special rock-soil medium widely distributed in islands and reefs in the South my country Sea. With the vigorous development of construction in the South my country Sea, the foundation improvement of calcareous sand has become an important part of the construction of islands and reefs. Calcareous sand is a special rock-soil material with irregular shape, many edges and corners, brittle texture and internal pores, easy to break and cement, which is quite different from ordinary terrigenous sand. [0003] Traditional foundation treatment usually uses methods such as dynamic compaction, preloading, displacement and chemical grouting. These methods are expensive, high in energ...

Claims

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Application Information

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IPC IPC(8): E02D3/00E02D3/12C12N1/20C12R1/07
CPCC12N1/20E02D3/00E02D3/12
Inventor 林胜强雷学文张彬董欢赵涵洋刘特
Owner WUHAN UNIV OF SCI & TECH
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