SEISMIC FRAGILITY CURVE OF NATURAL SLOPE BASED ON SLOPE FAILURE DATABASE

Abstract

Seismic fragility curve against slope failure with respect to peak ground acceleration (PGA) or instrumental seismic intensity (ISI) is constructed based on database of 4321 slople failures caused by Niigata-ken Chuetsu earthquake (2004). Since it is difficult to count the number of natural slope, the failure area ratio, which is the ratio of failure area to total area, is used for the fragility curve. Data of PGA and ISI at 131 sites are obtained from Japan Meteorological Agency and the National Research Institute for Earth Science and Disaster Prevention. Spatial distribution of seismic intensity is estimated by using Kriging based on the obtained data. The fragility curve is constructed by multiple regression analysis in which the objective variable is the failure area ratio, explanatory variables are slope angle and the seismic intensities. Failure area ratio can be obtained for arbitrary seismic intensity and slope angle by the proposed fragility cureve, e.g., the failure area ratio is around 0.1 when slope angle is 35 degree and PGA is 1350 gal or ISI is 6.3.