ABSTRACT
Earthquake-induced liquefaction is typically viewed as an undrained phenomenon, at least in engineering practice. Undrained element tests form the core of knowledge built around it. However, there is evidence to suggest that partial drainage could take place even during an earthquake. In this paper two dynamic centrifuge tests are presented, in which a part of the soil was enclosed in a flexible chamber that prevented fluid inflow and outflow. In one test outward lateral expansion of the chamber was allowed whereas in the other it was not. The evolution of pore pressures during the imposed seismic events showed that the hypothesis of undrained behaviour was inappropriate, as fluid flow and void redistribution took place, both inside and out of the chambers. The proximity of the boundaries defined the time frame for excess pore pressure dissipation. The capacity for lateral expansion controlled the displacement response of the chambers.
