Geosynthetic-Reinforced Soil Structures for Railways in Japan

Abstract

Geosynthetic-reinforced soil retaining walls (GRS RWs) have been constructed for a total length of about 150 km as of June 2013 mainly for railways, including high-speed train lines. After a full-height wrapped-around GRS wall has been constructed and the major residual deformation of the backfill and supporting ground has taken place, a full-height rigid (FHR) facing is constructed by casting-in-place concrete on wrapped-around wall face in such that it is firmly connected to the reinforcement layers. A number of this type GRS RWs performed very well during the 1995 Great Kobe and the 2011 Great East Japan Earthquakes. The seismic design code for railway soil structures has been revised taking into account such high-level seismic loads as experienced during the 1995 Kobe EQ. A number of conventional-type RWs and embankments collapsed during these and other earthquakes, heavy rains, floods, and storm wave actions. Many of them were reconstructed to this type GRS RWs and geosynthetic-reinforced embankments. Among a couple of new bridge types that have been developed, GRS integral bridge comprises a continuous girder of which both ends are structurally integrated without using bearings to the top of the facings of a pair of GRS RWs. The first prototype was constructed for a high-speed train line in 2011 and three more were constructed to restore bridges that fully collapsed by great tsunami during the 2011 Great East Japan EQ.