9781439834220.ch10

During up stroke cutting is achieved while during

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Unformatted text preview: (circular), or an oscillating head is employed for this purpose.2 These tunneling machines work on the principle of undercutting. During up-stroke cutting is achieved, while during down stroke the rotating cutter head draws the muck on the panzer type conveyor for its transfer to the rear. The resultant shape of drive/tunnel using such a unit is shown in figure 10.2(d).2 10.13 EXCAVATORS Use of excavators for tunneling operations for ground excavation, particularly in soft formations, has been in vogue since long. These excavators are used in following two ways: ● ● ● Excavator buckets and excavator with multiple attachments. Excavator mounted within a Shield. Excavator-Mounted Cutter Booms (Partial Face Machines for New Austrian Tunneling Method (NATM)). 10.13.1 EXCAVATORS MOUNTED WITHIN SHIELD1,6,7,13 10.13.1.1 Excavator buckets Buckets (fig. 10.9) of excavators are being used for excavation of soft soil such as clay, silt and sand and for mucking out of blasted rock. Buckets can be mounted on roadheader chasses, portals (gantries) and shields (described later). 10.14 EXCAVATOR WITH...
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