Mumbai University > Civil Engineering > Sem 8 > Construction Engineering

Marks: 10Marks

The Popular methods are:

1. Full face method

2. Heading and bench method

3. Drift method

4. Cantilever car dump method

Shield Method

The mechanized shield method is applied in the construction of tunnels in the central part of the city, where the tunnels are of considerable length; where archaeological sites are present, as well as to avoid open excavation works of considerable length along the major boulevards. The method involves mechanized excavation of soil in the front part of a steel cylinder, called “shield”, and assembling the tunnel construction under the protection of the back part of this cylinder. The machine is pushed forward by a system of hydraulic jacks, stuck in the tunnel construction in the back part of the shield.

The length of the shield depends upon the following:

storage required in shield

problem of governing or changing direction of motion.

The shape of shield can be circular, rectangular, or square, hexagonal sections. Parts of the shield

cutting edge or leading edge: It is the part that has to cut the soil in the front, when the shield is moved forward.

central part or trunk portion: This part of the shield provides strength to the shield like trunk providing strength to a tree.

Tail or rear portion: It is the backward most or rear part of the shield. This part of shield is store of the shield which accommodates segments, generator sets, compressor units, welding set, cement gun, circle boards, etc.