For
excavations, shields plays a major role. Slurry or hydro shield is
suitable for weak soils and for long distance excavation. In this method
cutter excavates the soil using rotary motion. This creates a hollow
space in the soil right in front of the boring machine. The slurry
shield works with an overpressure, which prevents collapse. The hollow
created by excavation is sealed by slurry a mixture of water and a
natural clay, to ensure that no ground water can enter. The excavated
soil after being mixed with the slurry is pumped out to the slurry
treatment plant at the surface of the ground. This streamlines and
automates the delivery of slurry. The slurry shield can also be equipped
with additional crusher, depending on kinds of strata.
Advantages
The use of slurry shield incurs following advantages :
- Pressure of the ground water is counterbalanced by the slurry
pressure.
- Since the excavated soil is discharged along slurry, the
tunneling is done in clean condition which makes long distance
tunneling possible.
- The face of the tunnel is supported by slurry pressure which
minimizes ground settlement.
Applications
Slurry shield tunneling machines are applicable for :
- River crossing tunnel.
- Deep tunneling.
- Deep mining operations.
- Tunneling for underground transportations etc.
