Abstract:

Nama tunnel, which is an integral part of QianGui railway updating project, is designed to be 2788m long. Crossing several fault zones, the tunnel has poor geological conditions. The exit portion of the tunnel is located on slide slopes, which has extremely complex geological conditions. Due to the tight construction schedule of the tunnel, it is determined to install an inclined shaft so as to provide more working faces. Such reinforcement measures as pipe roof, forepoling, grouting and steel arches are taken so that the tunnel can cross the fractured zones successfully. In the paper, the construction scheme of the tunnel and the countermeasures taken to cope with the poor geological conditions are presented.