活性炭固定微生物固化贵阳红黏土力学特性

微生物能够固化土体，但是在固化强度上还有待提高。为了增强微生物固化土体的力学特性，文章提出固定化微生物技术与微生物诱导碳酸钙沉淀技术（MICP）相结合的方法，即将掺量为0、4%、7%、10%、15%的活性炭与重塑红黏土均匀混合后，再通过MICP固化土体后进行常规三轴压缩试验，同时进行相同条件下在菌液瓶中有无胶结液与活性炭的生成碳酸钙的对比试验、有无活性炭重塑红黏土的常规三轴压缩对比试验。通过扫描电镜分析，得到试样的力学特性、活性炭在MICP过程中的作用、微观结构等试验结果。试验结果表明:在微生物固化土体过程中，活性炭作为固定微生物的载体，在MICP过程中对微生物起到“增效”的作用，在微生物诱导碳酸钙沉淀过程中提高了碳酸钙产量；同时，活性炭的有无及含量多少对微生物固化土体有重要影响，结合水膜厚度改变、碳酸钙填充孔隙及胶结作用使得红黏土抗剪强度有效C值大幅增加，有效φ值减小，剪应力峰值增加；加入活性炭使生物矿化环境得到优化，并在碳酸钙结晶时对晶体结构、形态产生了一定的控制作用，生成了以活性炭为“核心”具有一定结构的块体，而使土体的力学特性增强。该研究成果对微生物岩土技术以及工程应用具有重要价值。 

Mechanical properties of microorganism solidified red clay immobilized by activated carbon in Guiyang

Although microorganisms can solidify soil, its consolidation strength needs to be enhanced further. This work proposed a combination of immobilized microbial technology and microbial induced calcium carbonate precipitation technology (MICP). In this method, about 0, 4%, 7%, 10%, 15% of activated carbon is uniformly mixed with the remolded red clay, and the soil is solidified by MICP, then conventional triaxial compression tests are performed on soil samples. At the same time, comparison tests of generating calcium carbonate in the liquid bottle with or without the cement solution under the same conditions are carried out. By means of scanning electron microscopy analysis, the mechanical properties of the sample, the role of activated carbon in the MICP process, and the microstructure are obtained. The test results show that in the process of microbial solidification of soil, activated carbon acts as a carrier for immobilized microorganisms, which plays a role of the “enhancing effect” on microorganisms during the MICP process, and increases calcium carbonate production during microbial induced calcium carbonate precipitation. The presence or absence and content of the soil have an important influence on the microbial solidified soil. Combined with the change of water film thickness, filling of pores and cementation by calcium carbonate, the effective C value of the shear strength of red clay is greatly increased, the effective φ value is reduced, and the peak shear stress is increased. These changes demonstrate that adding activated carbon can optimize the biomineralization environment, and pose a certain control effect on the crystal structure and morphology during crystallization. Consequently, a block with a certain structure with activated carbon as the "core" is formed, and the mechanical properties of the soil are enhanced. This research would be valuable for future microbial geotechnical technology and engineering applications.