SAFETY ASSESSMENT OF FILL-SLOPES FOR AMPLIFICATION DEGREE OF EARTHQUAKE VIBRATION ON IRREGULAR GROUND AT CROSS-SECTIONAL VALLEY DIRECTION

Abstract

Extensive damage of the slope embankment for road and residential lands were occurred in many Earthquakes because of amplification of earthquake vibration on irregular ground. The amplification of the valley line direction ingredient is usually reported, but there are few examples that studied the influence that the amplification of the earthquake vibration of the valley right angle direction (cross-sectional direction) ingredient gives slope stability. In this paper, we studied some case-studies on cross-sectional irregular valley ground are clarified by using FEM analyses. Also, we discussed the influence that the geometric interference and impedance ratio and the amplification of the cross-sectional direction ingredient earthquake vibration by the frequency characteristic gave the slope of embankment. The effect of the cross-sectional shape of embankment on the characteristics of seismic amplification degree of acceleration is discussed for safety factor of slope stability. As results of research, the amplification was related to valley widthW , valley depth D and frequency characteristic f/fg greatly at earthquake time of the cross-sectional direction and the acceleration amplification was anticipated over 60% at the maximum. We estimated the fall of the safety factor of around several% to give to slope stability and showed that it was necessary to anticipate an effect of the valley shape of the cross-sectional direction in the stability evaluation adequately.