CENTRIFUGE MODEL TESTS ON THE SEISMIC STABILITY OF EMBANKMENT CONSTRUCTED ON CLAY DEPOSITS SUBJECTED TO CONSOLIDATION HISTORY

As a cause of the seismic damage to embankments, liquefaction of the sandy ground located under an embankment has been mainly focused in the past. However, many embankment damages were observed also in river levees constructed on non-liquefiable ground, in which thick clay and/or peat layers were de-posited, during the 2011 off the Pacific coast of Tohoku Earthquake. In this research, to investigate the dynamic deformation mechanism of an embankment constructed on a clay deposit which received a consolidation history, a series of shaking table tests in a centrifugal field were carried out by changing the consolidation state (i.e., normal consolidation or overconsolidation) of the clay deposit under an embankment, the embankment material, and the input level of an earthquake motion. The experiments have revealed that an embankment constructed on a normally-consolidated clay deposit and affected by the consolidation settlement showed a larger seismic damage compared to that on an overconsolidated clay deposit, although the embankment settlement due to the earthquake loading was smaller than that arising from the consolidation settlement of the normally-consolidated clay. This suggests that the stress state within the embankment changed from its initial state immediately after the construction of the embankment due to the consolidation settlement of the clay deposit. To estimate the seismic damage of an embankment constructed on a clay deposit, it is thought that the influence evaluation of the consolidation history in the clay deposit becomes important.