碱改性粉煤灰增强MICP固化砂土性能试验研究 English Version
Experimental study on the performance of alkali modified fly ash enhanced MICP solidified sand
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摘要: 碱改性粉煤灰在MICP技术中的应用，能够充分发挥其吸附性能，消减MICP作用过程中产生的氨氮，为环保型土壤固化技术开辟了新的途径。本文以碱改性粉煤灰作为增强体，开展了碱改性粉煤灰增强MICP固化砂土的宏观与微观试验研究，研究内容涵盖了固菌率测定、除氨率测定、碳酸钙含量测定、单轴抗压强度测定、渗透率测定以及扫描电子显微镜（SEM）观测。结果表明：①经过碱改性的粉煤灰对氨氮的去除效率显著提升，达到了62.6%，相较于未改性的粉煤灰，其吸附氨氮的能力提高了42.2%。②碱改性粉煤灰在微生物诱导碳酸钙沉淀（MICP）加固砂土的过程中，能够显著提高固菌率和胶结物的产量，当掺量为7%时，胶结物的生成比例达到了17.3%。③碱改性粉煤灰的加入有助于增强固化体的抗压强度和抗渗性能，当掺量为7%时，MICP固化砂土的抗压强度提高了2.6倍，渗透系数降低了两个数量级。Abstract: The application of alkali modified fly ash in MICP technology can fully utilize its adsorption performance, reduce the ammonia nitrogen generated during the MICP process, and open up new avenues for environmentally friendly soil solidification technology. This article conducts macroscopic and microscopic experimental research on alkali modified fly ash as a reinforcing agent to enhance MICP solidified sand. The research content covers the determination of bacterial fixation rate, ammonia removal rate, calcium carbonate content, uniaxial compressive strength, permeability, and scanning electron microscopy (SEM) observation. The results showed that: (1) The alkali modified fly ash significantly improved the removal efficiency of ammonia nitrogen, reaching 62.6%. Compared with unmodified fly ash, its ability to adsorb ammonia nitrogen increased by 42.2%. (2) During the process of microbial induced calcium carbonate precipitation (MICP) reinforcement of sandy soil, alkali modified fly ash can significantly improve the bacterial fixation rate and cement production. The bacterial fixation rate almost doubles, and when the dosage is 7%, the proportion of cement generation reaches 17.3%. (3) The addition of alkali modified fly ash helps to enhance the compressive strength and impermeability of the solidified body. When the dosage is 7%, the compressive strength of MICP solidified sand is increased by 2.6 times, and the permeability coefficient is reduced by two orders of magnitude.
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