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The work is to be 12 pages with three to five sources, with in-text citations and a reference page

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The work is to be 12 pages with three to five sources, with in-text citations and a reference page. In cut and cover tunneling, the structure is built in excavation and later on covered with some backfill material once the structure is completely built. This technique is mostly used when there is a shallow tunnel profile and at the time when the surface excavation is feasible. This technique is mostly used in underpasses, mined tunnels, and in flat terrains or in places where it is feasible to construct a shallow tunnel. In the construction of these tunnels, there are two approaches that are applied. top-down and bottom-up.

In top-down, the excavation walls support the tunnel’s ceiling and the roof. For depths of about 10 to 12 meters, this technique gets to be more economical than mined tunneling (Pan et al., 2006).

This kind of tunneling is applied in the making of long tunnels in rock masses in different surroundings. In order to have a proper job done, the method requires the right TBM machines and the right equipment. In this technique, the rocks give the upper hand of providing natural support for the tunnels. There are likelihoods, however, that the hard rocks might be disadvantageous to the tunnels.

In this technique, major shield methods are “earth pressure balanced (EPB)” and slurry machines. In order to select the right machine for the right jobs, some of the most important things to take care of are the condition of the ground, the condition of the surface, tunnel section dimensions, the distance being bored, alignment of the tunnel and the period to be taken for construction (Bilger, 2008).

Both shield methods operate in a closed face machine where the head part of the machine is closed and the rear part is in a different compartment. EPB turns the soil that is excavated into mud pressure than for the stability of the cutting face, holds it in that form. Due to this reason, it cannot be used in hard rock as it is necessary to turn this rock into a slurry. The slurry machine uses the slurry that gets pressure externally for the stability of the cutting face. This slurry uses a fluid conveyance to transport the soil that is excavated.