Experimental Study On Microorganisms Curing Basalt Residual Soil

Emei Mountain Basalt is widely distributed in Yungui area of southwest China.The residual soil,which has been left in situ by weathering of basalt,has many bad engineering characteristics,and the chemical curing agent is used in the soil solidification treatment,which will affect the surrounding environment greatly,so it is urgent to study a new kind of environmental curing method suitable for this soil.Microbial curing technology is a new kind of environment-friendly method to solidify the soil,which utilize microbial mineralization in nature and further adding human-controlled intervention.In this paper,the laboratory geotechnical test,micro-component analysis(XRD,XRF)and micro-structure analysis(SEM,EDS)were carried out on the soil of the experimental group,which was cured by the autogenous iron bacteria and the Bacillus pasteurii(a high yielding urease strain),and the distilled water control group.The microscopic mechanism of the solidified basalt residue soil by iron bacteria is studied in this study.This study can provide some reference for the development of microbial curing method of basalt residue soil,and the main research contents and results are as follows:(1)The morphological analysis and the determination of the related enzyme activity of the cemented substance produced by the autogenous iron bacteria.Among the three different forms of iron bacteria screened out,the XT03 strain is more suitable for microbial solidification of the reddish brown basalt residual soil.(2)The behavior of strain and the analysis of laboratory geotechnical test results.Compared with the mature MICP(microbial induced calcite precipitation)technology,the autogenous iron bacteria curing method is more suitable for being used for curing reddish brown basalt residual soil,and the shear strength,compressive properties and water characteristics of solidified soil were greatly improved.(3)Microscopic composition and microstructure analysis of soil solidified by iron bacteria.The addition of the autogenous iron bacteria improves the mechanical properties of the soil without changing the original chemical composition of the soil,the solidified soil is basically covered by iron cementation,the surface of the iron binder has a certain venation texture,and the whole structure of the soil is compacted and cemented evenly.