Laboratory Study on Soil Desaturation by Microbial Methods
摘要
The soil desaturation method for mitigation of sand liquefaction has gained interest in recent years. The application of microbes for various ground improvement studies has proven to be cost-effective and non-disruptive compared to other conventional methods. The potential of soil desaturation by introduction of non-pathogenic denitrifying bacteria is studied in this paper. This bio-chemical process used to induce partial saturation leads to the nucleation of gas bubbles within the soil pores which generate gas as final product. This evolved gas occupying the pore spaces shifts the soil matrix to quasi-saturated state affecting the rate of pore-pressure. Prior to the evaluation of soil strength properties, batch tests were conducted to understand the effect of initial nitrate concentration on generated gas volume. To understand the effect of microbial de-saturation on static behavior of the soil, undrained strain-controlled static triaxial tests were conducted for loose sand condition. Results showed increase in peak deviatoric stress after treatment, change being prominent in loose condition indicating enhanced resistance to static liquefaction. B-value and water content measurements were taken to monitor the change in degree of saturation. The rate of excess pore pressure development in undrained compression loading also showed a decreasing trend.