Experimental Study On MICP Solidification Of Muddy Soil

Water conservancy projects and water environment management will produce a lot of silt every year.Silt generally has the characteristics of high water content,high compressibility,and high organic matter content.Improper treatment will not only occupy land resources,but also cause secondary pollution.Resource utilization is the ultimate outlet for silt treatment and disposal.In engineering,chemical curing agents are often used to solidify silt soil,which has a great impact on the surrounding environment.Therefore,it is of practical significance to study new green treatment methods to solidify silt.Microbially Induced Carbonate Precipitation(MICP)is a relatively new type of soil improvement technology.This technology has a significant effect on strengthening sandy soil.Recently,it has also been used by many scholars to solidify clay soil.In this paper,a high-yield urease strain(Bacillus pasteurii)was used to solidify the silt soil.This study can provide a reference for the improvement of the engineering performance of the silt soil by microbial solidification.The main research contents and results are as follows:(1)This paper studies the influence of the concentration of the cementing liquid,the shearing method,the type of calcium source,and the curing period on the strength of the MICP solidified soil.Because the addition of cementing liquid will introduce cations,which will affect the strength of silty soil,this paper separately studied the effect of cementing liquid in MICP solidified silty soil on the solidified soil.The research results show that MICP solidified silty soil can increase the internal friction of silty soil.When the cement concentration is 1.0 mol/L,the internal friction angle of MCP solidified silty soil is the largest.(2)The addition of salt solution in electroosmosis can speed up the drainage of cohesive soil,and Ca Cl₂can provide calcium source for the MICP reaction.This paper developed a method of combining electroosmosis and MICP to solidify silt,and compared three sets of tests:Ordinary electroosmosis,electroosmosis in which the anode enters the Ca Cl₂solution,microbe-electroosmosis,and microorganism-electroosmosis method increases the drainage of the soil and reduces compared with the ordinary electroosmosis method and the electroosmosis method in which the anode enters the Ca Cl₂solution.The surface settlement of the soil is increased,and the shear strength of the soil is increased.(3)MICP spraying method and MICP mixing method are used to treat silt soil.In the collapse test,the anti-disintegration performance of the soil sample treated by MCP spraying method is better than that of plain soil,and the more treatment times,the better the anti-disintegration performance.