PS Veligonda Project
One of India’s greatest water transfer systems is being carried out using Tunnel Boring Machines beneath the Nagarjuna Sagar National Park, the country’s largest tiger sanctuary. In order to complete Tunnel No. 2 RPPL is deploying a Robbins Double Shield TBM.
To handle the difficult ground conditions, the Double Shield machine has 67 backloading cutters with a 20-inch diameter. Low penetration rates in the hard rock can be made up for by running the machine at a higher-thannormal RPM thanks to specially developed drive motors. The cutter head can move vertically while compressing the ground, enabling overboring. Additionally, the machine features a probe drill that enables geology to be checked 30 metres (98 feet) in advance of the TBM. The drill can rotate 360 degrees and also be used as a grout consolidation drill. To pump any water away from the tunnel face, large 40 kW (54 hp) dewatering pumps are installed on the backup system. The TBM constructs 300 mm (12 inch) thick concrete segments in a 6+1 configuration as it drills, resulting in a 9.2 m final tunnel diameter (30 ft).
One of the largest conveyor systems ever deployed in India is used for muck transport.
|Value of Project||INR 50 Crores|
|Client||Water Resources Department, Govt. of Andhra Pradesh|
|Award Date||September 2018|
|Completion Date||September 2019|
|Machine Type||Double Shield TBM|
|Tunnel Type||Circular Shape|
|Tunnel Length & Diameter||509 Meters 10.0 m (Cross section 78.56 Sqm)|