Case Studies: Current Projects
Robbins/MHI EPBs to Extend Delhi Metro
- Machine Type: EPBM
- Number of TBMs: 2
- Diameter: 2 x 6.5 m (21.4 ft)
- Tunnel Type: Rail
- Tunnel Length: 2 x 2.0 km (1.2 mi)
- Owner: Delhi Metro Rail Corporation
- Contractor: Continental Engineering Corporation/Soma JV
- Location: New Delhi, India
Project Overview
Phase II of the New Delhi Metro Extension Project is an ambitious plan to add 53 km (33 mi) of new rail lines to cut transportation times, particularly when the city hosts the Commonwealth Games in 2010. Owners Delhi Metro Rail Corporation (DMRC) recently completed Phase I of the project in November 2006, adding 65 km (40 mi) of track and 59 stations. PhaseII, at a cost of USD $1.8 billion, involves multiple soft ground tunnels to be bored by Earth Pressure Balance Machines (EPBMs) between underground stations excavated by cut and cover.
On February 1, 2007,Robbins and Mitsubishi Heavy Industries (MHI) signed a contract with the CEC/Soma JV for two 6.5 m (21.4 ft) diameter EPBMs, back-up systems, and cutting tools. The machines were manufactured by Robbins using components from the U.S., India, and China. Both machines were built using both MHI and Robbins designs.
On May 15 2008, the first of the two TBMs was launched from an 18 m (60 ft) deep shaft at the Jor Bagh station site. The machines are boring parallel 2.0 km (1.2 mi) tunnels connecting the Udyog Bhawan and Green Park areas in New Delhi, as part of the BC-16 contract. The second machine was launched from the same site during the last week of June 2008.
The tunnels range from 8.6 - 14.0 m (28 - 46 ft) below the water table in sandy silt, silty sand and gravels. Both EPB cutterheads feature a 55% opening ratio to allow a smooth flow of muck and to avoid clogging the cutterhead. The machines are using several types of tungsten carbide bits for boring in soft but abrasive ground. Continuously erected lining along the length of the tunnel consists of reinforced concrete segments 275 mm (11 in) thick.
Updates of this project will be posted as boring continues.
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