Seismic response of vibroflotation reinforced coral sand foundation through shaking table tests

The liquefaction damage in dredger coral sand foundation mainly occurs when these materials are subjected to earthquake action. In the past practical engineering, the dredged loose foundations were used to be reinforced by vibroflotation, a traditional foundation reinforcement method. This paper investigated the impact of vibroflotation on the enhancement of liquefaction resistance by the shaking table. Sampled after the earthquake, the microfabric evolution is assessed by μCT system. The macroscopic results from shaking table tests showed that the vibroflotation can effectively inhibit the growth rate of the excess pressure ratios. Meanwhile, the peak excess pressure ratios of vibro-treated foundation are significantly smaller. Moreover, the study uncovers vibroflotation also resists the sandy softening and the stiffness reduction caused by strong shock. The development patterns of dynamic shear stress-strain hysteresis loops show the vibro-treated foundation is more resistant to stiffness attenuation. The microfabric assessment includes the evolution of the particles and the pores. The less increasing CNave and less decreasing APD reveals that vibro-treated foundation can prevent the damage of earthquake better due to the vibro-caused densification. Similarly, both CNave and K50 shows the vibro-point position gets better anti-seismic capacity when compared with the model center. Overall, the results of the microfabric evolution show that more acute variation happens on the untreated foundation after the earthquake, indicating the great improvement of anti-seismic capacity due to vibroflotation.