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Unformatted text preview: ed lumps can be handled effectively at
the face itself, thereby no problem during the subsequent muck-handling route.
In large sized tunnels simultaneous mucking and rock fragmentation are achieved
that enables effective utilization of the resources.
Compared TBM tunneling, investment costs are much less, and tunnel profile is
not restricted to a particular shape. However, the rock type, tunnel’s overall dimensions (size, shape, length), location and utilization of the equipment governs the © 2005 by Taylor & Francis Group, LLC 248 SURFACE AND UNDERGROUND EXCAVATIONS ● economy. During tunneling by hammering availability is extremely high (60–80%
of excavator time compared to 30–50% in primary breaking).5
Smaller tunnels than 30 m2 cross-section, and tough rocks without presence of natural
planes of weakness, the performance of this technique may not be satisfactory. 10.12 PARTIAL FACE ROTARY ROCK TUNNELING MACHINES2
In partial face either a pilot hole is reamed to achieve the desired tunnel size...
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- Spring '14