Another brick in Delhi Metro wall, with minimal noise

NEW DELHI: The Delhi Metro Rail Corporation (DMRC) is using a trench cutter for the first time, on the lines of Chennai Metro, to construct a diaphragm wall at Sadar Bazar metro station under Phase-IV on the Magenta Line.
Diaphragm walls are built for underground stations and a trench cutter is an excavating machine. While the soil at this station is rocky, metro officials said the trench cutter is applicable to all soil conditions and results in low noise and vibration emissions.
"Generally, the construction of the diaphragm wall is carried out with the help of the Hydraulic Grab D-wall machine. As the soil type at Sadar Bazar metro station under construction site mainly comprises hard rock, a trench cutter has been mobilised at site for the construction of a diaphragm wall at Sadar Bazar metro station," said a DMRC official.
The trench cutter is an excavating machine that operates on the principles of reverse circulation. It is made up of a heavy steel frame with two gear boxes at the bottom of the frame. Cutting wheel drums fitted with a series of teeth are fixed to the gearboxes. They rotate in opposite directions.