| In the city of Tomakomai、 Hokkaido、 the seismic behavior of soft ground and of a road embankment built on such ground have been observed、 toward investigating the seismic performance of a road embankment constructed on soft ground and improving seismic engineering. Earthquake observations on soft ground started in 1991 at two locations、 one where volcanic ash soil predominates and the other where sandy soil predominates. Observation records have been obtained for 17 earthquakes、 including the Hokkaido Toho-Oki earthquake (Mj8.2)、 and they have been used to clarify the seismic behavior of soft ground、 whose complexity makes its seismic behavior nonlinear. Earthquake observations started at a road embankment in 1996、 and records have been obtained for 9 earthquakes whose maximum amplitudes ranged from less than 10 cm/s/s to the more than 100 cm/s/s of the 2003 Tokachi-Oki Earthquake (Mj8.0). This study uses these records to examine the nonlinear seismic behavior of a road embankment. The results show that the seismic behavior of soft ground and the road embankment is nonlinear、 that a cross-sectional area of the embankment behaves as an integrated system、 and that the low-order natural frequency is roughly the same in the ground as in the embankment. |
