| The 2011 Tohoku Earthquake and other large earthquakes in recent years in Japan have caused relatively large cracks on the crests of some embankment dams. Immediately after the 2011 Tohoku Earthquake, special safety inspections were carried out at over 300 dams in the affected area. As a result of these inspections, more than 10% of all inspected dams reported some damages. This ratio rose to 18% for embankment dams. Damage to embankment dams included relatively wide and/or long cracks mainly on the crests of earthfill dams. After the 1995 Kobe Earthquake, cracks were also observed on the crest of the Kinjoike dam, an old earthfill dam with a height of 15m located about 30km from the epicenter. The width of the crack on the crest was narrow about 1cm, but the crack extended deep into the dam when the dam was excavated to perform repairing work while checking the crack extension. However, no sliding deformation was observed at the Kinjoike dam. Results of safety inspections of embankment dams after large earthquakes in Japan have raised awareness of the importance of evaluating cracks of embankment dams. It is necessary to evaluate tensile strengths of materials of embankment dams, but almost no tensile strength tests using materials of embankment dams have been carried out. In this paper, we firstly introduce cracking generated on embankment dams due to recent large earthquakes. Next, we report the results of laboratory direct and splitting tensile tests using core material of an existing rockfill dam. |
