Study On Experiment And Mechanism Of Clay Reinforced By Microbial Induced Mineralization

Microbial mineralization refers to the fact that certain microorganisms can produce some crystalline and non-crystalline inorganic compounds during the process of metabolism,which plays the role of filling and cementing in the geotechnical materials,and therefore,the engineering properties of geotechnical materials can be enhanced.In recent years,researchers at home and abroad have conducted a lot of research on microbially induced carbonate precipitation(MICP)technology and achieved fruitful results.And some of these results have been applied to engineering practice.With the further development of microbial geotechnical engineering,the application of MICP technology in foundation treatment has aroused great interest among people.At present,it is urgent to find an environment-friendly and economical foundation treatment method in the southeast coastal areas of China.This paper conducts relevant experimental research on the premise of the situation aboveFirst of all,Sporosarcina pasteurii is used to induce calcite precipitation,and it is necessary to activate and amplification culture the S.pasteurii firstly.By measuring the changes of bacterial concentration and urease activity of the microbial solution with time,the growth curve of the microorganism was obtained,which is helpful to select suitable culture conditions to cultivate the bacterial solution for MICP experiments.Secondly,the silt soil samples were made by mixing method and treated with MICP.Through the mechanical properties test and microstructure analysis of the samples cured to a certain age,it is proved that the technology can effectively reinforce the soft clay,and the reaction is nearly completed in the curing period of about 14 days.The unconfined compressive strength of the samples is significantly increased,and the permeability is decreased.While the internal friction angle of the samples is basically unchanged,the cohesion is significantly increased,and the compression coefficient and compression index are also significantly reduced.The microbially induced carbonate precipitation can fix the Ca2+in the soil sample,precipitate calcite crystals to bond soil particles together.and therefore,the mechanical properties of soil can be enhanced.Finally,the sand-clay soil mixture samples were treated with microbiological grouting,and it is found that the unconfined compressive strength of the treated soil samples is significantly increased,and the modification effect of cementation reagent concentration on samples with different sand content is significantly different.Different from the morphology of calcium carbonate crystals generated in coarse soil samples reinforced by microbiological grouting,the calcium carbonate crystals of this experiment are stacked flake or granular.At present,there are few researches on MICP reinforcing fine soil in China.The experimental studies in this paper further verifies the possibility of applying the technology of microbiological mineralization to modify fine-grained soil especially silt soil,which can provide useful reference for similar study and practical engineering.