Definition - What does Conventional Tunneling mean?
Conventional tunneling describes the cyclic construction of underground tunnels of any shape where there is access to the excavation face. Conventional tunneling suggests an arbitrary definition: in the past it has excluded the use of tunnel boring machines (TBM). But in recent years the use of TBMs has become more common place and thus is increasingly included in the definition for conventional tunneling.
Employing conventional tunneling techniques is known as the conventional tunneling method (CTM).
Trenchlesspedia explains Conventional Tunneling
Because there is access to the excavation face, conventional tunneling is considered a very flexible process and is preferred in situations where there is a variation in ground conditions or tunnel shape. This flexibility includes the ability to vary the support, the blasting technique and size, ring closure time and the excavation technique as well as other factors.
Typically, the steps included in this cycle include excavation by drill, drill and blast, or basic mechanical excavators, the use of drilling fluid to evacuate the cuttings and placement of structural supports such as steel ribs, soil, rock bolts or lining. Sizes of these tunnels range from 0.5 meters to 4 meters in diameter.