| 摘要 |
PURPOSE: A pilot tunnel for a 2-arch tunnel is provided to improve the bearing effect when blasting a tunnel by supporting a central wall using a rockbolt, to shorten a period of construction by securing a space for moving construction machinery freely and to increase the advance when blasting a tunnel. CONSTITUTION: The pilot tunnel for a 2-arch tunnel comprises primary and secondary pitheads(11) formed on both longitudinal ends of a tunnel, an expansion unit(13) connecting the primary pithead(11) and the secondary pithead, a central wall installed to the center of the pitheads(11) and the expansion unit(13) continuously, and a rockbolt(50) inserted to the upper bedrock of the pilot tunnel and provided with a projection(51) projected partially to the inside of the tunnel. The construction method of the pilot tunnel for a 2-arch tunnel comprises the steps of: constructing pitheads(11) on both ends of a tunnel; constructing an expansion unit(13) between the pitheads(11) to be wider than the width of the pitheads(11); and installing a central wall to the pitheads(11) and the expansion unit(13).
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