基于MICP技术的生物岩土材料强度性能及碳酸钙结晶过程优化

Study on Strength Properties of Bio-geomaterial and Optimization of Crystallization Process Based on MICP Technology

微生物诱导碳酸钙沉积(MICP)技术在地基加固、防渗堵漏、土壤污染治理和防沙治沙等领域被广泛应用,其中微生物诱导过程中生成的沉积产物对砂土基生物岩土材料性能有重要影响.因此,对生物矿化材料在制备过程中因环境因素的不确定性引起矿化材料不确定和力学参数取值不确定性问题的研究尤为重要.本文开展了微生物诱导矿化过程影响因素的室内试验研究.以巴氏芽孢杆菌为培育菌种,通过调控氮源、碳源、时间、温度等环境因素的影响水平,应用SEM、EDS、XRD、红外衍射等方法对诱导生成的矿化物进行表征.设计正交试验,以碳酸钙生成率为指标,通过极差和方差分析,确定了优选方案:20~30℃环境温度,菌液接种量为1%,矿化时间为24h,营养盐浓度为50%.并以此为优化条件,以砂土为岩土基质,应用MICP技术制备生物岩土材料,测试其无侧限抗压强度,分析强度成因机理,为该技术在岩土工程中的应用提供理论依据和试验数据.

MICP technology has been widely applied to geotechnical engineering fields,such as foundation reinforcement,plugging,soil pollution control and sand prevention,in which the mineralizations generated in the process of microbial induction have great influence on the performance of soil base MICP material.Thus,the research of mineralization material and mechanical parameter uncertainties resulted from environmental uncertainty become increasingly important.The indoor study of influencing factors of microbe-induced mineralization were performed.With Bacillus pasteurii being culture,the SEM,EDS,XRD and IR diffraction are utilized to characterize the mineralization by the adjustment of nitrogen source,carbon source,time,temperature and other environmental factors.The proper program was determined by range analysis and variance analysis with the formation rate of calcium carbonate being target during designing orthogonal test.The obtained program was as follows:ambient temperature of 20~30℃,inoculation amount of bacterial liquid of 1%,mineralization time of 24 h,and nutrient concentration of 50%.On the basis of above optimal program,with sand soil being geotechnology matrix,the measurement of unconfined compressive strength and the analysis of strength formation mechanism were performed on bio-geomaterial prepared by the MICP technology,which provided theoretical foundation and experimental data to the MICP appliance to geotechnical engineering.