微生物矿化对黏土强度特性的影响

微生物矿化技术应用于浅层坡体固化有很强的优势，是一种环境友好、可持续发展的处理方法。利用球形赖氨酸芽孢杆菌属kp-22菌作为试验用菌诱导碳酸钙沉淀处理四川省地表黏土。采用不同浓度的菌液、氯化钙和尿素溶液对黏土处理后进行直剪试验，探讨微生物矿化对黏土强度特性的影响。研究结果表明，微生物矿化作用能明显增大黏土的抗剪强度；且菌液浓度越高，矿化效果越好。随着氯化钙浓度的提高，试样的强度先增大后减小，在氯化钙浓度为0.5~0.75 mol/L时达到峰值；在尿素浓度为0~1.0 mol/L的范围内，抗剪强度随尿素浓度的增加而增加；当氯化钙和尿素分别为0.75 mol/L、1.0 mol/L，菌液吸光值OD600为1.2时，抗剪强度达到最大值，矿化效率最高。建立了考虑菌液和CaCl2浓度的内摩擦角的经验关系，分析了强度变化的内部机理。

Influence of Microbial Mineralization on Strength Characteristics of Heavy Metal Contaminated Clay

Microbial mineralization technology has a strong advantage in the solidification of shallow slope. This is an environmentally friendly and sustainable approach. A test bacterium Bacillus sphaeroides kp-22 was used to induce calcium carbonate precipitation to treat surface clay in Sichuan Province. Direct shear tests were conducted for the surface clay before and after mineralization using different concentration of bacterium to investigate the effect of microbial mineralization on the strength characteristics of clay. The results show that the shear strength of clay can be significantly improved by microbial mineralization. And the higher the concentration of the bacterial solution, the better the mineralization effect. With the increase in CaCl2 concentration, the strength of the sample first increases and then decreases, reaches the peak when the concentration of calcium chloride is 0.5 ~ 0.75 mol/L. In the range of urea concentration from 0 to 1.0 mol/L, the shear strength increases with the increasing urea concentration. When calcium chloride and urea are 0.75 mol/L and 1.0 mol/L respectively, and the absorbance value OD600 of bacterial solution is 1.2, the shear strength reaches a maximum and the mineralization efficiecy is the best. The empirical relations between shear strength parameters and their influence factors are established, and the internal mechanism of strength change is analyzed.