Examining the seismic behaviour of partially saturated sand using centrifuge shaking table tests

Similar to fully saturated sand, the partially saturated sand can also liquefy under certain conditions during earthquakes. This study aims to characterize the seismic behaviour of partially saturated sand. Centrifuge shaking table tests were performed using the IWHR horizontal-vertical centrifuge shaker. The experimental results indicate that the liquefaction resistance of the partially saturated sand increases with decreasing the degree of saturation and with increasing the initial effective stress right before shaking. The boundary between the liquefied and un-liquefied sand becomes deeper and deeper during shaking.

Development of dynamic impact cone for assessing induced partial saturation (IPS) as liquefaction mitigation technique

Liquefaction of saturated loose sands during an earthquake has been a great concern for practicing earthquake engineer because of its damaging effects. Current liquefaction mitigation techniques used in practice are expensive. A new innovative mitigation technique which is cost effective was proposed by Yegian et al. [1] called “Induced Partial Saturation” (IPS). This method involves in generating gas bubbles within the pores of fully-saturated sand and transformed it to partially-saturated sand. This paper described the development of a dynamic impact cone to assess the effect of this IPS treatment on saturated loose sand specimens. This dynamic impact cone consists of a cone, rod, ruggedized pressure transducer, string pot, and DAQ. The cone which has pressure transducer incorporated at its tip was driven into fully and partially (treated) saturated sand specimens prepared in the laboratory. The excess pore pressures and penetrations depth per impact of the two specimens were compared. The tests results such as the excess pore pressure and the penetration indicate that the impact penetration on the fully-saturated specimens liquefied sand, but could not liquefy the partially-saturated sand. Therefore the concept and development of this dynamic impact cone has promising future applications.