Investigation of liquefiable property and S-wave velocity distribution focused on coal ash used for rail yard embankments

Abstract

In the 2011 Great East Japan Earthquake the rail yard embankment constructed by use of coal ash was damaged by severe liquefaction, resulting in the differential settlement of railway track. In the railway the settlement is limited to ensure safety, however the evaluation method for differential settlement is not established. It is thus necessary to establish the evaluation method for the differential settlement of railway track induced by liquefaction. In this study, cyclic undrained triaxial tests for the fill material contained coal ash were performed to validate whether it was liquefied. It was found that the fill material was possibility to be liquefied sufficiently. In addition, field level survey and surface wave exploration method were conducted to examine the effect of the thickness of liquefiable layer and S-wave velocity distribution on differential settlement caused by liquefaction. The results revealed that the differential settlement is concerned with distribution of the S-wave velocity and the thickness of the liquefiable layer.