9781439834220.ch10

Water assisted cutting although suppresses the dust

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Unformatted text preview: tion of dust and heat while performing cutting operations by the roadheader are obvious. Water assisted cutting although suppresses the dust but results humidity. The proper ventilation could control these problems. © 2005 by Taylor & Francis Group, LLC TUNNELING BY ROADHEADERS AND IMPACT HAMMERS 245 4 3 4 7 8 3 5 2 6 1 1 I I 2 II Figure 10.6 Working sequence of roadheaders. Left: Attacking from bottom to top. Right: Attacking perimeter. Bottom: Attacking middle of face first then sides. 10.8.1 GROUND SUPPORT It is an established fact that roadheaders produce a smooth, proper sized and shaped openings comparing conventional drilling and blasting technique of tunneling. Blasting damages the surroundings but with this technique there could be a saving of 10–15% in support costs for the excavation requiring temporary support; or in suitable ground conditions situation, the need of support may be eliminated completely.6 The amount of support required at the face, in fact, determines roadheader’s utilization,3 as outlined below: Support Type None: Rock bolts, or Shotcrete: Shotcrete and rock bolts; or steel sets: Steel sets with full lagging: % of cutting time available during the working cycle at the face 60–80 40–50 30–35...
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This document was uploaded on 02/12/2014.

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