Study On Reinforcement Mechanism And Engineering Characteristics Of Bio-enzyme Solidified Soil

The soft soil in coastal area has the characteristics of high compressibility,high moisture content,large natural pore ratio and low strength,so the soil reinforcement is often needed in engineering.At present,most of the projects are mixed with cement and lime in soil to improve the strength of soil.There are some disadvantages such as polluted environment and high cost in construction.This paper relies on the Study on the reinforcement mechanism of silt dredger fill based on urease producing bacteria induced mineralization of National Natural Science Foundation Project(NO.51708497),and Study on the strength formation mechanism and durability of enzyme-solidified silt dredger fill soil foundation of Ningbo Natural Science Foundation Project(NO.2017A610306).Biological enzyme is applied from road performance to soil solidification in coastal areas.Adding biological enzyme,the cement and the suitable mix ratio were designed to cure three kinds of soils in Ningbo.On the basis of the experimental study on the mechanical properties,the effect of the enzyme on the reinforcement of three kinds of soil was analyzed,and the microstructure characteristics of the bio-enzymatic solidified tidal flat silt were analyzed,and the engineering characteristics and the strengthening mechanism of the bio-enzymatic solidified tidal flat silt were discussed through the combination of the macro and micro tests.This article mainly carries out the research work and the result are as follows:(1)Firstly,the characteristics of unconfined compressive strength and the characteristics of splitting strength were obtained through the unconfined compressive strength test and the splitting test of three kinds of enzyme-cured soil.It analyzed the influences of the dose,the dosage of cement and the age of the enzyme on the strength of soil.The results showed that the strength of the mud and silty clay was increased remarkably,and the enhancement effect of the soil was not obvious.According to the test results,it is concluded that the clay mineral played an important role in the biological enzyme.(2)Secondly,combined with XRD test,the mechanism of biological enzyme on the mud of tidal flat was discussed.The analysis shows that the biological enzyme occurs in the process of curing tidal sludge,which has no effect on the chemical composition and crystal structure of soil and can promote the hydration speed and hydration degree of cement.(3)Thirdly,combined with SEM test,the microscopic morphological characteristics and pore characteristics of the mud from the bio-enzymatic solidified beach were discussed qualitatively and quantitatively.The analysis shows that the addition of biological enzymes can shorten the spatial distance of soil particles,increase the coupling force between particles,and promote the formation of cementitious materials,and make them more compact.(4)Finally,combined with macro-microscopic test,the mechanism of the consolidation of the mud was preliminarily discussed,which provided the theoretical guidance for the application of the bio-enzyme curing agent in the practical project in Ningbo.