A JV of Hyderabad-based SEW Constructions, Prasad Constructions Works and Iranian contractor Sabir successfully bidded for the 18.8 km Veligonda tunnel project, located on the right bank of Srisailam Reservoir. The client is the Department of Irrigation of the Government of Andhra Pradesh.As the finished diameter is 7 m and an old double shield hard rock TBM of 7.9 to 8 m in diameter is not available, a new double shield hard rock TBM is the preferred method. The TBM is planned to commence from the exit portal. The contractor is currently in talks with the TBM manufacturers. Muck removal is planned by continuous conveyor belt. The selection of suppliers is also under negotiation. Interested firms are invited to submit their quotations.The Veligonda project envisages withdrawal of water through the Veligonda straight tunnel, with a carrying capacity of 85 cu m per second, into a new reservoir which is being formed by plugging three gaps. Works are in progress downstream of the tunnel, including the open channel / canal and the dams to shape the reservoir, which makes the completion of the tunnel a critical component for the successful completion of the project and utilisation of the water. The water tightness specifications have not been mentioned by the owner / client and no water loss measurements would be undertaken at the inlet and exit. The geological strata is dominated by quartzites varying from 180 MPa to 230 MPa, shales and phyllites of varying strengths from 80 MPa to 140 MPa. No shaft, adits or caverns are necessary. At the exit end the tunnel, the bed is only 26 m under the current ground level. The planned date to start tunnelling is January 2007. Construction time: 36 months. Construction cost: USD142 million. Given the above criteria and lack of stiff prerequisites from the client, the JV is opting for honey comb precast lining or bolted segments with a simple economical design. The number of segments per ring depends on the design. The JV wishes to commission the lining design to experienced firms who can save on the construction costs thanks to efficient design. Contact Mr. Srikanth C., Vice-President Business Development, SEW Constructions Ltd, 6-3-871, "Snehalatha", 1st Floor, Greenlands Road, Begumpet, Hyderabad 500016. Tel. +91 40 2340 2153 / 2340 3273 or 5551 2157, fax +91 40 2340 5016, e-mail csrikanth@eth.net, sewconhyd@eth.net or sewcon2001@yahoo.com. Visit http://sewconstructions.com/home.html and www.sabir-co.com 39/05.Hindustan Construction, in joint venture with Coastal Projects, has received a letter of award for INR7.35 billion for investigation, design, execution and construction of the second tunnel for the Pula Subbaiah Veligonda project, a 18.8 km 9.2 m-internal diameter tunnel for the water transmission system linking Srisailam Reservoir up to Guntur-Kurnool road to join into a feeder canal. The scheme will transfer water from the Krishna river to the Pakasam, Nellore and Cuddapah districts of the state. The contract also includes operation and maintenance of the tunnel for a period of two years after successful commissioning of the tunnel. The company's 60% share of order is INR4.41 billion. The project is to be completed in 60 calendar months. Visit www.hccindia.com 21/07.For the Veligonda I project, one Herrenknecht hard rock double shield machine will be used. The diameter of the cutter head is 7,960 mm, the cutter head power is 2,800 kW (8 x 350 kW), the total thrust is 14,418 kN and the cutter head torque is 8,470 kNm. The tunnel is followed by an open channel which would carry water to the downstream reservoir. The access to the tunnel is from the open channel. The TBM assembly area has been prepared at the transit point where the tunnel discharges water into the canal/open channel. The first batch of the machine part has arrived at the Port in Chennai and is awaiting customs clearance. The boring is expected to start from August onwards. Honey comb concrete segments will be installed, with four segments per ring. The segments will be produced nearby the project site by the JV of contractors, SEW Construction, Prasad Constructions Works and Sabir. The supplier of the segment plant and moulds is Herrenknecht. A conveyor belt, which is being designed by in-house and local experts, will be used for rock evacuation. The Veligonda project has two tunnels of 7 m and 9.2 m inner diameter. The second, 9.2 m ID tunnel parallel to the 7 m ID tunnel has been awarded recently to Hindustan Construction and Coastal Projects. Click in/42. Visit www.herrenknecht.com 23-24/07.
