2025 Volume 25 Issue 5 Pages 5_136-5_145
On August 11, 2009, an earthquake centered in Suruga Bay caused the collapse of the embankment of the Tomei Expressway. The reason for the embankment collapse was that the mudstone used for the lower part of the embankment had lost its strength and permeability due to the action of water over many years, causing the groundwater level in the embankment to rise. The collapse was estimated to have been caused by seismic shaking. Following this disaster, inspections of embankments under similar conditions were carried out, and it was confirmed that the strength of embankments where spring water was confirmed was low. This paper describes the transition of seismic countermeasures for expressway embankments and design criteria for mudstone embankments and introduces a series of efforts from inspection to evaluation and implementation of countermeasures. It also discusses issues regarding ensuring the seismic resistance of existing embankments using mudstone.
