负压作用下微生物矿化粉质黏土的性能试验研究

Experimental Study on Properties of Microbial Mineralized Silty Clay Under Negative Pressure

微生物矿化技术(MICP)可以有效提高土体的强度,在学术界受到广泛关注,目前主流研究对象是渗透系数较大的砂土,而对于渗透系数较低的粉质黏土的研究并不多见。在微生物矿化处理粉质黏土的过程中施加负压作用,进行直剪试验、碳酸钙分布试验和扫描电镜观察,综合评价不同负压作用下微生物矿化技术对粉质黏土的加固效果。结果表明:在适当的负压作用下(0.7~0.8倍标准大气压)微生物矿化技术加固粉质黏土的效果十分显著,其黏聚力和内摩擦角相比于自然矿化的土样分别提高了52.32%和31.58%;在扫描电镜下观察可见,在0.7~0.8倍标准大气压下矿化处理相比于自然矿化处理,土颗粒之间生成的方解石晶体数量更多,分布更密集,对土颗粒孔隙的胶结填充作用更明显;负压作用对土样矿化的均匀性也有很好的改善。

Microbial mineralization technology(MICP) can effectively improve the strength of soil, so it is widely concerned in academia. At present, the main research object is sandy soil with large permeability coefficient, but the research on silty clay with low permeability coefficient is rare. In the process of microbial mineralization of silty clay, negative pressure was applied. Direct shear test, calcium carbonate distribution test and scanning electron microscope observation test were carried out on soil samples. The reinforcement effect of microbial mineralization technology on silty clay under different negative pressures was evaluated comprehensively. The results show that under the appropriate negative pressure(0.7-0.8 standard atmospheric pressure), the effect of microbial mineralization technology on the consolidation of silty clay soil samples is very significant, and its cohesion and internal friction angle are increased by 52.32% and 31.58% respectively compared with those of natural mineralization soil samples;it can be seen from the scanning electron microscope that under the negative pressure of 0.7-0.8 standard atmospheric pressure, compared with the natural mineralization treatment, the amount of calcite crystals generated between soil particles is more, the distribution is more intensive, and the cementation filling effect on the pores of soil particles is more obvious;the negative pressure effect also has a good improvement on the uniformity of mineralization.