Design and construction of geosynthetic-reinforced soil structures for Hokkaido high-speed train line

The southern part between Shin-Aomori Station (at the north end of Main Island) and Shin-Hakodate Station (at the south end of Hokkaido Island) of a new high-speed train line called Hokkaido Shinkansen is nearly completed as of the end of 2013 and will be opened in 2015. In a range of 37.3 km at the south end of Hokkaido Island, a number of various types of geosynthetic-reinforced soil (GRS) structure were constructed: i.e., (1) GRS retaining walls (RWs) having full-height rigid facing for a length of about 3.5 km, having fully replaced the conventional type RWs; (2) in total 29 GRS bridge abutments, having fully replaced the conventional type bridge abutments; (3) a GRS integral bridge, the world-first one at Kikonai; (4) three GRS box culvert structures integrated to adjacent GRS RWs; and (5) nine GRS protection structures at the tunnel entrance. These GRS structures are those that have been constructed most densely ever for railways, which is definitely so for high speed trains. In this paper, the design and construction of these GRS structures is described while several lessons learned from this project are summarized.