Chennai Metro Rail

The Chennai Metro Rail project included designing and constructing two corridors, Corridor 1 (Washermanpet – Airport) and Corridor 2 (Chennai Central – St. Thomas Mount). The underground works were divided into five packages. TYLin provided technical assistance to the contractor to design and construct Corridor 1 (Packages UAA-02 and UAA-03) and Corridor 2 (Package UAA-04).  

Packages UAA-02, UAA-03, and UAA-04 were 3.6 kilometers, 2.9 kilometers, and 3.4 kilometers long, respectively. Each consisted of long twin tunnels bored mainly in younger alluvium of sandy and clay-like soil. Bedrock was encountered in some stretches of the tunnel alignment. The bedrock consisted of Archaean charnockite and sedimentary formations, mainly shale and sandstone. Three Earth Pressure Balance (EPB) Tunnel Boring Machines (TBM) were used to excavate the tunnels. The segmental lining included an internal diameter of 5.8 meters. Rings were formed by 275-millimeter-thick segments. 
 
TYLin’s responsibilities included analysis of the geological conditions along the alignment and assessing for EPB pressures definition, TBM break-in and break-out procedures at stations, TBM cutting tool recommendations, site equipment foundation designs, design of the fiber reinforced sacrificial rings for station crossing, and creation of guidelines for ground treatment for cross passages and recommendations on mixed face conditions excavation.