溶液环境下微生物诱导碳酸钙沉积影响因素研究

Study on influencing factors of microbial induced calcite precipitation insolution environment

现有的微生物诱导碳酸钙沉积(MICP)技术的研究对象大多是简单离子化学环境下的松散砂土,而实际工程中往往需要面对各种不同环境下形成的土体。以江苏东部沿海地区海相吹填粉土的化学环境为依托,选用巴氏芽孢杆菌进行溶液环境下微生物诱导碳酸钙沉积试验。通过定量分析研究了环境温度、环境pH、氯化盐、土体中胶结阳离子含量等环境因素对微生物诱导碳酸钙生成量的影响规律。结果表明,在14~36℃时碳酸钙的生成量随着温度的升高而增加,总体呈上升趋势;当溶液pH为9时,碳酸钙生成量最多,并且碱性较强的溶液(pH为10~11)比弱碱性溶液(pH为7~8)诱导生成的碳酸钙量更多;溶液里高浓度的氯化盐能够抑制碳酸钙的生成,相比而言同浓度下氯化钙比氯化钠更易抑制碳酸钙生成;原始土体中少量的两种胶结离子之间没有相互抑制的作用,当土体中胶结阳离子浓度总和一致时,碳酸钙产量基本一致。研究结果可为实际注浆时采用MICP技术加固土体提供有效的依据。

The objects of existing microbial induced calcite precipitation （MICP） technology are mainly loose sand insimple ionic chemical environments. However, the soil to be improved in practical engineering is often formed underdifferent sedimentary and chemical environment. Few corresponding studies involved the MICP in different types ofsoil and environment. Therefore, the MICP experiments of Sporosarcina pasteurii in the solution environment wereconducted based on reclamation soil in the eastern coastal areas in Jiangsu Province. The influence of environmenttemperature, pH, the content of chlorate, and the contents of cementing cations on the MICP were analyzed by quan-titative tests in the laboratory. The results showed that the production mass of calcium carbonate increased with the in-crease of temperature in the range from 14~C to 36~C, generally presenting a rising trend. In addition, most calciumcarbonate was generated when the solution pH was 9. And the production of calcium carbonate in strong alkaline solu-tion （pH 10-11 ） was more than that in weak alkaline （pH 7-8）. A high concentration of chlorate solution could in-hibit the formation of calcium carbonate, and under the same concentration of calcium chloride and sodium chloride,the calcium chloride was more likely to inhibit the generation of calcium carbonate than sodium chloride was. Therewas no mutual inhibition between the two kinds of cementing cations in the original soil. When the total cementingcation concentration was constant, the production of calcium carbonate was basically the same, regardless of the pro-portion of each cation. The results may provide the effective guidance for actual soil grouting reinforcement process byusing the MICP technology.