Summary of Lahmeyer International’s tunnelling work

Goldisthal, Germany Baglihar, India (located on the Chenab river in Jammu & Kashmir) Mohale dam, Lesotho Swabi SACRP, Pakistan Pehur high level canal in Pakistan
•Type of tunnelling: •Type of tunnelling: •Type of tunnelling: •Type of tunnelling: •Type of tunnelling:
Access tunnel to power house:7.3m diameter and 1300m long.Two headrace tunnels: 7m diameter and 820m long each. Two diversion tunnels: 10.5×10.6m, 400m and 540m long respectively. Diversion capacity of 3000m3/sec.Headrace tunnel: 2069m long with a discharge of 430m3/sec. Water conveyance transfer tunnel from Mohale reservoir to Katse reservoir. (32km long and 4m in diameter). Two tunnels. The first is the rehabilitation of an existing 4.9m diameter, 3.4km long tunnel with a discharge of 50m3/sec. This is used for irrigation, hydro power and water conveyance.The second tunnel is a new auxiliary one for irrigation water conveyance with hydro power potential. (5.3m diameter, 3.4km long and with a discharge of 60m3/sec). Three tunnels. a) Baja – irrigation water conveyance. b) Gandaf Rock – irrigation water conveyance with hydro power potential. Diameter of 3.4m and 2.2km long. c) Gandaf Soft – irrigation water conveyance with hydro power potential. Diameter of 3.1m and 1.8km long. All tunnels have a discharge of about 28m3/sec.
•Methods: •Methods: •Methods: •Methods: •Methods:
Drill and blast — NATM. Lining— Primary (shotcrete SN anchors) and secondary (concrete and steel). Drill and blast – NATM. Lining: first (shotcrete) and second (concrete lining, t=50cm). Excavation by two double shielded telescopic TBMs. One is driving from the inlet structure, the other from the outlet structure. With a precast concrete segmental lining (d=25cm). Repairs included dental concreting/shotcreting with concrete invert. Drill and blast – NATM and a shotcrete lining with concrete invert. a) Drill and blast – NATM. Shotcrete lining with concrete invert. b) Drill and blast – NATM. Primary lining: shotcrete. Secondary lining: concrete. c) Shield. Segmental concrete and steel lining.
•Schedule: •Schedule: •Schedule: •Schedule: •Schedule:
The whole project is scheduled for 1997-2003. Excavation works were completed in 2000 with a delay of about four months Diversion tunnels – 7 months. Headrace tunnel – 24 months. Access tunnel to power house – 6 months Tailrace tunnel – 4 months. the whole project was started in 1998 and is expected to finish in 2004. At the present time there is a delay of three months. 13.5km of tunnel completed. Completed in 1999 a) Completed on time in 2000. b) Current delay of four months. c) Completed on time in 2000.