Dynamic response of liquefiable sand foundation improved by bio-grouting

The liquefaction induced in loose and saturated sand foundations by dynamic loading such as earthquakes and the “static” liquefaction induced during rainfall and groundwater rise in loose sand slopes can lead to catastrophic damages such as the subsidence of road embankments, landslides and the floating of embedded structures like pipelines and tunnels. Compared with the traditional ground improvement methods, one of advances in bio-mineralization enables the rapid microbial induced carbonate precipitation, which is introduced by transporting the bacterial cells and nutrient solutions into loose sand foundations for the purpose of ground improvement. This new ground improvement process is called bio-grouting. It is the leading edge of ground improvement research, which has many advantages such as small disturbance, short construction period, notable reinforcement and low energy consumption. This study is attempted to investigate whether the bio-grouting is applicable to the improvement of liquefiable ground through dynamic triaxial tests and shaking table tests. First, a brief introduction to the research, development of microbial induced carbonate precipitation and bio-grouting technology is presented, and a practical bio-grouting treatment method applicable to improvement of liquefiable sand foundations is described. Second, the anti-liquefaction performance and other dynamic performance of the bio-grouting sand ground are studied through dynamic triaxial and small scaled shaking table tests, and a comparison between the bio-grouting and the traditional ground improvement methods is made. The test results show that the anti-liquefaction performance of bio-grouting samples and models is greatly improved. In short, the bio-grouting technology has potential to be used in engineering applications and broad application prospect in liquefiable sand foundations.