Experimental Research on Bamboo-Truncating Tunnel Portal for Single-Track Railway

Model experiments with a geometric similarity ratio of 1∶30 were carried out to investigate the ground pressure and internal force of up and down bamboo-truncating tunnel portals for single-track railway. In these experiments, grade of up-slope and crossing angle between portal and railway center line were considered. The experimental results showthatground pressure and internal force around a tunnel portal are related to the thickness of overburden, the grade and the crossing angle: when the crossing angle is 90°, maximumground pressure and bend moment are at the invert bottom of a tunnel portal; when the crossing angle is 45°and 60°, maximum bend moment is on the side walls of a tunnel portal.