Study On The Change Of Clay Engineering Properties Under The Action Of Sphingomonas

Microorganisms are an important part of the soil system,and their growth,reproduction,and migration processes affect the engineering properties of the soil.In this thesis,the influence of microorganisms on the properties of clay engineering is studied by sampling inspection and indoor experiment.The community structure of the microorganisms in the contaminated soil from life sources was determined through experiments,and the microorganism Sphingomonas with the largest number in the contaminated soil from life sources was selected as the test microorganism.In this thesis,the growth curve of Sphingomonas in soil was tested through experiments,and the growth curve was divided to correspond to the culture time.In the experiment,the relationship between the engineering properties of the clay and the concentration of Sphingomonas was obtained.In addition,the changes in the engineering properties of clay in the whole development process of the Sphingomonas community(the growth period of the number of microorganisms,the prosperous period of the number of microorganisms,and the period of the decline of the number of microorganisms)are also summarized.Finally,the comprehensive experimental results analyzed the law and mechanism of the influence of Sphingomonas on the engineering properties of clay.The results show that:(1)Sphingomonas is the bacteria with the highest abundance at the species level in the polluted soil from living sources tested.(2)According to the dynamic change characteristics of the sphingomonas community in the soil,the dynamic change process in the soil is divided into the number growth period,the prosperity period,and the decline period,the time required for the number of Sphingomonas to reach the peak and the environmental capacity decreases as its concentration increases.(3)The growth process of Sphingomonas has a significant impact on soil geotechnical properties.During the growth period of the number of Sphingomonas communities,the plastic limit,liquid limit,and electrical conductivity of the soil showed a downward trend,and the internal friction angle,cohesion,and unconfined compressive strength showed an upward trend;In the prosperous period,the plastic limit,liquid limit,and electrical conductivity of the soil rebound slightly,and the internal friction angle,cohesion,and unconfined compressive strength are on the rise;In the decay period,the plastic limit and liquid limit conductivity of the soil gradually decrease and become stable,and the internal friction angle,cohesion,and unconfined compressive strength show an overall upward trend.The soil viscosity increases with the growth and reproduction of Sphingomonas.(4)The concentration of Sphingomonas has a significant influence on the soil geotechnical properties.The concentration of Sphingomonas has a positive correlation with the plastic limit,liquid limit,electrical conductivity,and internal friction angle of the soil,and has a linear positive correlation with the cohesion of the soil and the unconfined compressive strength.(5)The growth process of Sphingomonas also affects the water loss and cracking characteristics of the soil,Its dynamic growth process will slow down the rate of soil water loss and cracking,and reduce the scale of soil crack development.The greater the initial concentration of Sphingomonas,the more obvious its effect.(6)EPS will wrap and adsorb with soil particles,affect the degree of flocculation of soil particles,affect the ability of soil particles to absorb water and water,change the structure of clay minerals,and form a honeycomb-network structure in the soil,which will affect the physical and mechanical properties,hydraulic properties,and structural characteristics of the soil.The thesis has 29 pictures,9 tables,and 86 references.