- Bored tunneling – In the case of soft soil, a shield is used before excavating the soil. In rocks, rocks are drilled and blasted. Depending on the method used, the tunneling process can be described as-
- Full face heading
- Heading and bench method
- Ring Drilling method
- Groove method
- Side Drift method
In the full-face heading, the entire face is drilled and blasted in one operation. This method is economical, speedy and most widely used. In the heading and bench method, the top portion is blasted after drilling and loading. Lower portion is treated as one or more benches and drilled as well or blasted horizontally or vertically.
There are various shield mechanisms, which are used. Some of them are illustrated in the following slides -
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