微生物矿化作用对红黏土的影响研究

Effect of microbial mineralization on red clay

引入微生物矿化技术,利用其中巴氏芽孢杆菌的代谢产物对红黏土进行改性研究。对微生物矿化作用的红黏土试样开展常规物理指标试验,分析试样含水率、密度、比重、孔隙比和颗粒粒径的变化。利用三轴固结不排水剪切试验,测定土体的抗剪强度指标,并结合扫描电镜分析微生物矿化下红黏土的微观结构特征。结果表明:巴氏芽孢杆菌诱导碳酸钙沉淀胶结充填红黏土空隙作用明显,土样经过恒温养护10d时的作用效果最佳,红黏土的物理性质朝着工程性质好的方向发展、抗剪强度有所增强。从SEM图像分析,红黏土试样中生成碳酸钙晶体填充胶结于土体孔隙,加强了土壤颗粒间的连接。

The technology of microbial mineralization was applied to the modification of red clay,in which the metabolites of bacillus pasteurii were used.Routine physical index tests were carried out on the red clay samples to analyze the changes of water content,density,specific gravity,porosity ratio and particle size by the modification. The shear strength of soil was determined by triaxial undrained shear tests.The microstructure of red clay was observed by SEM.The results show that the Bacillus pasteurii can induce the precipitation and cementation of calcium carbonate to fill voids of red clay effectively,and the soil sample was the best after 10 days of curing with constant temperature.With the addition of bacteria and the occurrence of microbial mineralization,the physical properties of the red clay changed significantly,and the internal friction angle and cohesion of the sample increased.Analysis of SEM images shows that calcium carbonate crystals were generated in the red clay sample which filled in the pores of the soil and strengthen the connection between soil particles.