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微生物诱导生成碳酸钙沉淀(MICP)技术是一项新兴的原位灌浆技术,通过微生物和钙盐作用形成碳酸钙沉淀可改善可液化砂土的抗液化特性。NH4+作为表征碳酸钙结晶过程的重要因子,可充分反映对可液化砂土的改良效果。选用巴氏芽孢八叠球菌,采用Ca(CH3COO)2、Ca(NO3)2和Ca Cl2三种钙盐与尿素混合溶液的营养盐,探讨采用NH4+来表征可液化砂土的微生物固化过程。结果表明:NH4+离子浓度变化能够表征MICP对可液化砂土改良的效果,其中Ca(CH3COO)2营养盐改善可液化砂土效果最佳;营养盐的用量也对可液化砂土的加固效果有明显的改善。通过对固化后试样的渗透性和超声波速的测定,也验证了加强效果。
Microbial-induced calcium carbonate precipitation (MICP) technology is an emerging in situ grouting technology that forms calcium carbonate precipitates by the action of microorganisms and calcium salts to improve the liquefaction resistance of liquefiable sands. As an important factor to characterize the crystallization process of calcium carbonate, NH4 + can fully reflect the improvement effect on liquefiable sand. The selection of Bacillus pasteuriensis, the use of Ca (CH3COO) 2, Ca (NO3) 2 and Ca Cl2 three kinds of salt and urea mixed solution of nutrients, to discuss the use of NH4 + to characterize liquefiable sand microbial solidification process. The results showed that: the change of NH4 + ion concentration could characterize the effect of MICP on liquefiable sand improvement, of which the effect of Ca (CH3COO) 2 nutrient leaching liquefaction sand was the best; the effect of nutrient salt on liquefiable sand was Significant improvement. By the permeability of the cured sample and the determination of the ultrasonic velocity, the strengthening effect was also verified.