2024 Volume 10 Issue 37 Pages 1401-1406
Recent occurrences of major earthquakes have been associated with a series of foreshock and/or aftershock events (i.e., 2011 Tohoku and 2016 Kumamoto) induced reliquefaction of sand grounds. Influence of these small magnitude events needs to be examined as it may result in increased/decreased reliquefaction potential. Catastrophic damages were observed during these repeated earthquakes around the world, whereas studies on this line of research are limited. In the present study, centrifuge model experiments were performed to examine the influence of foreshocks-mainshock-aftershocks sequence on reliquefaction potential. Five shaking events (two foreshocks followed by a mainshock and two aftershocks) were applied in sequence with sufficient time between two shakings. Acceleration amplitude and shaking duration of the mainshock event is twice that of the foreshock and aftershock events. Results show that complete liquefaction was observed only in the mainshock, whereas significant excess pore pressure was recorded in the foreshock and aftershock events. Beneficial effects of seismic preshaking were reported in the second foreshock and were completely eliminated during the mainshock owing to the complete liquefaction. Further application of aftershocks rebuilt resistance to excess pore pressure generation and regained beneficial effect of seismic preshaking. From these presented results, it was concluded that liquefaction destroys preshaking benefits obtained from foreshocks and the liquefied sand ground possesses low resistance to future reliquefaction.
