2015-07-21
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The … industry has been the primary constructor of shafts. Depth of several thousand … are common. In public works projects, such as sewer tunnels, shafts are usually only a few hundred feet deep and because of their high … are avoided in the design stage whenever practical … shafts find many uses. Being essentially vertical tunnels, shafts involve the same problems of different types of ground and water …. Inflowing water is far more … during construction and generally intolerable during operation. Hence, most shafts are concrete-lined and …, and the lining installation usually follows only a short distance behind excavation. The shape is usually …, although, before current mechanized excavation methods, mining shafts were frequently rectangular. Mining … is called shaft sinking. In soil, shallow shafts are frequently supported with interlocking … sheet piling held by ring beams.
FOLLOW UP ACTIVITIES
Speak on:
Basic procedures in tunneling operations.
The construction of tunnels.
Unit 8: FAMOUS TUNNELS
Lead in:
1. What famous tunnels do you know?
2. Why are they called famous?
Find the following terms and memorize their meaning.
| bank blow into determination divergence draw off duct banquet brick cylinder bricklayer chamber compressed air controversy drainage enlarge exhausts engineering failure fraction heading internal combustion lining motor traffic | flooding frames impede impel inch leaks prop propel purposes survey technique temporary underwater tunnel screw sealing shaft shield shotcreting sinking surface approach |
