MECHANISM OF LIQUEFACTION IN REPEATED EARTHQUAKE VIBRATION

摘要

During Great East Japan Earthquake happened in March 11 2011,reclaimed ground in Urayasu city,Chiba prefecture,Japan,experienced severn liquefaction not only in the main shock but also in an aftershock with a maximum acceleration of 25gal.In some areas,liquefaction happened in the aftershock is even morn serious than that happened in the major shock.Based on the observed data,a series of dynamic-static analyses,not only considering the earthquake loading but also static loading during the consolidation after the earthquake shock,are conducted in sequential way just the same as the scenario happened in the earthquake.The calculation is conducted with soil-water coupling finite elementfinite difference (FE-FD)analyses based on Cyclic Mobility Model.From the analysis,it is known that some small sequential earthquakes,which cannot cause liquefaction of a ground in an independent earthquake vibration,cannot be neglected when the ground has already experienced liquefaction after a major vibration.It is also known from the analyses that the influence of the aftershock to the long-term settlement of clayed ground is not negligible.