EFFECTS OF THE STIFFNESS OF SOFT CLAY LAYER ON STRONG MOTION RESPONSE

抄録

This paper shows the effects of the stiffness of an underlying soft clay layer on the strong motion response. Seismic behavior of Kobe's artificial islands during the 1995 Hyogo-ken Nambu earthquake is studied by centrifuge shaking table test. During the earthquake, it is known that the liquefaction damage on artificial islands was different at each site. The authors consider that this is due to the stiffness of the clay layer underlying the reclaimed ground because of the degree of consolidation. The model grounds used for the centrifuge test were made with clay and fill material sampled from Kobe Port Island, and the clay material was consolidated at two different degrees of consolidation, which correspond to those of the Port Island array observation site and the south-western part of Rokko Island. First, from the viewpoint of the reproducibility of in-situ behavior, we compared the seismic response and the ground settlement obtained from centrifuge test with those of the observation data of Port Island. Next, we compared the seismic response of the test results of the different degree of consolidation. It is found that the difference of stiffness due to the degree of consolidation of the underlying clay layer significantly affects the seismic behavior of reclaimed ground. The large damage is not always come to being on the ground with soft clay layer.