Recent research and practice of GRS integral bridges for railways in Japan

Abstract

Geosynthetic-reinforced soil (GRS) integral bridge was developed to overcome several inherent serious problems with conventional type bridges typically comprising a simple-supported girder (or girders), RC abutments and approaches of unreinforced backfill: i.e. high construction/maintenance cost while bumps immediately behind the abutments; a low stability of the bearings and backfill against seismic and tsunami loads; massive abutment structures; needs for piles etc. A GRS integral bridge is constructed by constructing firstly a pair of GRS walls and an intermediate pier (or piers) if necessary; secondly lightly steel-reinforced full-height-rigid (FHR) facings by casting-in-place concrete on the wall face wrapped-around with the geogrid reinforcement; and finally a continuous girder with both ends integrated to the top of the FHR facings. The background of the development of GRS integral bridge is explained. The first four case histories, completed in 2012 and 2014, are reported.