The 10.7km expansion will be carried out by drill and blast with a cross sectional area ranging between 2.7 x 2.6m and 9.7 x 8.6m. Grouted bolts (7 to 24 bolts of 2-4m in length per metre), mesh and sprayed concrete (70 to 100mm thick) will support the ground.
"The main challenge in this copper mine, the largest in the world, are the seismic conditions and geologic forces", says Thomas Birtel, CEO of Strabag, which owns Zu¨blin.
The work will increase the life of the mine by 50 years and is being undertaken some 80km south of Santiago for Codelco, the world’s largest copper producer. The mine first opened in 1904 and produces more than 400,000m3 of copper every year. Work is scheduled to complete by the end of 2016.
