Design horizontal seismic coefficient evaluated from road embankments with and without damage by recent earthquakes

Abstract

This study focuses on road embankments with and without damage by the 2007 Noto-Hanto earthquake and by the 2011 off the Pacific coast of Tohoku earthquake in order to investigate: a) the relationship between the global safety factor evaluated by pseudo-static analysis and the degree of actual damage, and b) the value of the horizontal seismic coefficient which should be employed in the conventional design method for preventing severe damage. For these purposes, a series of numerical analyses based on the parameters evaluated by the field and laboratory tests were performed in the present study. The results from dynamic centrifuge model tests on road embankments conducted previously by the first author were also analyzed to supplement a lack of data. The following conclusions can be derived from the results presented in this paper: a) the crest settlement tended to increase with decreasing global safety factor with the consideration of seismic force, which suggests that the global safety factor evaluated by pseudo-static analysis can qualitatively explain the degree of earthquake-induced damage of embankments, and b) the value of the design horizontal seismic coefficient to prevent severe damage with crest settlement larger than 40 cm could be obtained by 0.20∙A_max/620, where A_max is the predicted maximum acceleration of an earthquake.