A DESIGN METHOD FOR REINFORCED CENTER PILLARS OF TWIN-BORED TUNNELS

Abstract

The number of twin-bored tunnels has been increasing despite a lack of established design methods. In particular, the mechanism of stress concentration to center pillar caused by the excavation of tunnels is not obvious yet. Therefore, few study of stress condition of center pillar has been carried out so far. In this report, the design procedure of center pillar proposed in past times has been modified based on the results of in situ measurements and analysis using finite element methods. In addition the design procedure of reinforced center pillar has been introduced.