Performance evaluation of liquefaction resistance of a MICP-treated calcareous sandy foundation using shake table tests
摘要
Calcareous sandy foundations are susceptible to liquefaction when subjected to dynamic loading such as seismic or wave loading. The microbially induced calcite precipitation (MICP) treatment is a relatively new method to improve the liquefaction resistance of calcareous sand. In this study, several shake table tests are conducted to evaluate the seismic performance of MICP-treated calcareous sandy foundations. The influence of seismic history on dynamic performance of calcareous sand foundation is analyzed. The results indicate that the dynamic response of the soil after MICP treatment, including the excess pore water pressures and vertical settlements, can be divided into three main stages: the stable stage, rapid development stage, and gentle stage. The liquefaction resistance of MICP-treated sand is improved significantly. However, the surface accelerations for the MICP-treated models are amplified. Thus, when designing the treatment program, it is necessary to consider the tradeoff between the improved liquefaction resistance and the minimized undesirable amplified ground surface motions. The liquefaction resistance of MICP cementitious calcareous sand is related to intergranular cementation strength and relative density of soil and particle arrangement. The history of vibration improves the relative density of the foundation, and the liquefaction resistance significantly reduces the surface settlement.