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Q: Among the different methods of tunnel construction, identify the one which is NOT suitable for rocks.
  • A. Shield method
  • B. Drift method
  • C. Full face method
  • D. Heading and benching method
Correct Answer: Option A - Shield Method– • It is used in soft soil for driving a tunnel through water bearing strata. • It is an equipment which acts as a bridge with roof for workers. It consist of a circular steel ring with a transverse diaphragm. The essential part of shield are hood, tail, cutting edges and propelling jacks. • The excavation and lining of tunnel can be carried out under protection of shield. Different methods of tunnel construction suitable for rocks– • Drift method–In this method, a drift is first driven of appropriate size, usually of 3000 mm. The drill holes are provided all round the drift in entire cross section of tunnel. • Full face method–The full face method is adopted only for small tunnels whose dimensions do not exceed about 3 m. • Heading and Bench method–This is the method usually adopted for all railway tunnels.
A. Shield Method– • It is used in soft soil for driving a tunnel through water bearing strata. • It is an equipment which acts as a bridge with roof for workers. It consist of a circular steel ring with a transverse diaphragm. The essential part of shield are hood, tail, cutting edges and propelling jacks. • The excavation and lining of tunnel can be carried out under protection of shield. Different methods of tunnel construction suitable for rocks– • Drift method–In this method, a drift is first driven of appropriate size, usually of 3000 mm. The drill holes are provided all round the drift in entire cross section of tunnel. • Full face method–The full face method is adopted only for small tunnels whose dimensions do not exceed about 3 m. • Heading and Bench method–This is the method usually adopted for all railway tunnels.

Explanations:

Shield Method– • It is used in soft soil for driving a tunnel through water bearing strata. • It is an equipment which acts as a bridge with roof for workers. It consist of a circular steel ring with a transverse diaphragm. The essential part of shield are hood, tail, cutting edges and propelling jacks. • The excavation and lining of tunnel can be carried out under protection of shield. Different methods of tunnel construction suitable for rocks– • Drift method–In this method, a drift is first driven of appropriate size, usually of 3000 mm. The drill holes are provided all round the drift in entire cross section of tunnel. • Full face method–The full face method is adopted only for small tunnels whose dimensions do not exceed about 3 m. • Heading and Bench method–This is the method usually adopted for all railway tunnels.