EXCABATION OF TUNNELS COVERRED WITH A SLIGHT THICKNESS OF EARTH RIGTH NUDER RAILS WITH NATM

Abstract

Higasiyama tunnel is a subway tunnel of mountain type in the urban area over a total length of 1, 567.5m. And its structure is featured by paralles of single track at different elevations for a span of 495m on the starting side and by a double track for the rest 1, 072.5m portion. We report the results of Urban NATM that excavated the subway tunnels covered with slight thickness of earth right under Keishin-Line and a prefectual road. And also we made an exact survey at any time to keep the safety on the ground.