Non-linear site response : a focus of thick sedimentary deposits. Learnings from Japanese strong motion recordings

抄録

This contribution presents a statistical analysis of the non-linear behavior that can be detected on strong motion recordings obtained on thick Japanese sedimentary sites from the KiK-net and K-NET networks, together with a comparison with other site types involving thinner deposits and/or higher fundamental frequencies. The non-linear effects are quantified by comparing various kinds of site-response characteristics (surface-to-borehole spectral ratios, H/V spectral ratios) for moderate to large motion to their weak motion counterparts. While a non-linear behavior can be detected on thick and thin sites as well, thick sites do not exhibit the peculiar high-frequency reduction predicted by most non-linear simulations because of increased damping. This inconsistency constitutes a warning on the use of classical non-linear degradation curves derived from measurements at limited confining pressures corresponding to depths not exceeding a hundred meters.