Numerous river dykes and road embankments were suffered severe damage during the 1994 Hokkaido-Nanseioki Earthquake and the 1995 Hyogoken-Nanbu Earthquake. The main cause of the damage was considered to be the liquefaction of the foundation, the behavior of which has not yet been well understood. Based on the results of past studies, the foundation of an embankment was divided into three zones to examine the failure modes. One-dimensional on-line seismic tests, which were conducted by a combination of element tests and computer seismic response analyses, were performed for such zones of actual river dykes damaged during earthquake. The cumulative lateral displacement values obtained by the tests were compared with the measured embankment-crest settlement data, which showed that the sliding failure due to liquefaction under the toe of slope of such an embankment is found to be the most detrimental ofaU failure modes.
River dykes and road embankments are frequently damaged during earthquakes. Since rivers have long embankments and small breakage of embankments may be permitted where such failure dose not cause a disastrous overflow, it has long been a cherished desire of engineers to establish a method of predicting the magnitudes of deformation of river dykes under earthquakes. The liquefaction of foundation, the behavior of which is not yet well realized, is considered to be the main cause of the damage. Based on the results of past studies, the foundation of an embankment was divided into three zones to examine the failure modes. Considering the embankments of the Shiribeshi-Toshibetsu River struck by the 1994 Hokkaido-Nanseioki Earthquake, the authors performed one-dimensional on-line seismic tests which were a combination of element tests and computer seismic response analyses under the boundary conditions of failure modes in the three zones of each embankment.
