Dynamic response analysis of geogrid reinforced steep embankment subjected to an earthquake

A geogrid reinforced steep embankment 6.5 m high at a distance of 33 km from the epicenter was subjected to the Kushiro offshore earthquake of January 1993, but kept its stability. The maximum seismic acceleration was estimated at 310 gal. This embankment proved to have a high aseismatic performance, because although it had been designed under the ordinary condition only, it maintained its stability during the earthquake. In the first place, seismic response analysis by the total stress method using actual seismic waves was performed. Then, evaluation of stability by the seismic coefficient method was reviewed by the current Japanese design method (PWRI). From these analyses, the following findings were obtained; l)The reinforced zone behaved as an integrated soil mass, and 2) direct sliding did not occur since the horizontal earth pressure in the back of the reinforced zone did not reach the maximum level at the time of maximum inertia force of the reinforced zone.