Some Construction Aspects of Tarbela Dam

Tarbela Dam (Pakistan) including upstream blanket and two auxiliary dams requires 181,500,000 cu yd of earth and rock fill obtained two-thirds from borrow and one-third from required excavation. Nearly all materials are processed to attain desirable gradation. Placing rates have reached 301,000 cu yd per day and 6,550,000 cu yd per month. Excavation is by shovels up to 15-cu yd size, using 44-cu yd scrapers and 6-cu yd and 9-cu yd draglines. Hauling involves 110-ton bottom dump and 35-ton and 70-ton rear dump trucks. Processing separates various size ranges for zone requirements, or grizzlies out oversize material. Transport of materials up to 12 in. is largely by conveyor belt, from which bottom dump trucks distribute the materials. Compaction is handled principally by 10-ton vibratory rollers. Other earth and rock work includes a 6,000-ft airstrip, 8 miles of access road, cofferdams (4,500,000 cu yd), and a large switchyard.