Model tests on the stability of GRS integral bridge against tsunami load

Abstract

The girders of a great number of bridges were washed away and/or their approach fills were significantly eroded by the great tsunami of the 2011 Great East Japan Earthquake. Many of the bridges close to coastal lines are required to have high resistance against not only seismic load but also tsunami load. The geosynthetic-reinforced soil integral bridge (GRS-IB) has been developed and it has been verified that this new type bridge has high seismic stability. This paper reports results of small scale hydraulic model tests showing substantially higher stability against tsunami load of GRS-IB than the conventional type bridge, having a girder supported by bearings. This high performance can be attributed to the fact that the girder, the abutments (i.e., facings) and the approach fills of GRS-IB are structurally integrated to each other. Accordingly the resistance of the backfill against erosion is also very high.