Abstract: Tunnel construction is a complex engineering task due to difficulties and logistics involved in boring and digging over the extended distances underground. However, thanks to advances in equipment technology, complex tunnelling projects are accomplished throughout the world. The tunnel boring machine (TBM), also known as mole, has made the construction of these tunnels possible, in hard or soft rock strata. Two major categories of TBM are used in the modern-day tunnelling process. TBM with full-face excavation and TBM for partial excavation. TBM with full-face excavation includes gripper and shield TBMs, and TBM for partial excavation includes enlarged TBM and unique machines for non-circular sections. To protect the TBM from fault zones, support systems like rock bolts, pipes, grout injection, and freezing are provided over or in front of the cutterhead. Roofing shield support system is useful during advancement in fractured rock. This roofing shield support system safeguards the crew members working behind the cutterhead from rock falls. Shield tunnelling is mainly useful in hard rock with moderate stand-up time and in fractured rock because the shield extends entirely over the complete machine from the cutterhead portion and provides safety to the entire structure.

Key words: TBM, tunnel, roofing shield, supportsystem hard &soft rock, fault zone,rock bolt

| DOI: 10.17148/IARJSET.2021.8329