DESIGN AND CONSTRUCTION OF THE LONGEST TWIN BORE TUNNEL WITH A CENTER-PILLAR BENEATH A RESIDENTIAL AREA

Abstract

Kitasuma Tunnel is the longest twin bore tunnel with a center-pillar which has been rarely constructed in Japan. Because lkm long tunnel bored just beneath a residential area, the design of the center-pillar is an important consideration. Based on result of F. E. M. analysis, auxiliary method with pre-grouting and PU-IF were applied before excavation forsupporting ground surface. Rock Split method were applied for boring in the middle part, very hard rock area. In this paper, the basic idea of the design and construction for twin bore tunnel based on the result of measurements is mentioned.