New approach of tunnel alignment design in complex geological formations

摘要

A new railway line of about 17 km length was planned between Dongbaeksan and the neighboring town Dokye to improve the existing decrepit railway system. New line about 18 km of the distance will almost be in circular alignment tunnels owing to the difference of elevation about 380 m. Since the geology of the area is rather unusual compared to the normal in South Korea, extensive geological investigations have been carried out to prepare geological maps and profiles along the planned tunnel routes. The tunnel will almost be in sedimentary rock formations, such as limestone, sandstone, shale, coal, etc. and be near abandoned mines. Various rock formations have the complicated, altered those rocks, but are well developed with laminated formations. Each rock formations have been classified using the Q-system and the cost of tunnel excavation, support has been estimated and compared for three alternative lines in the design stage. Based on these estimates, the final route of the railway line was chosen.