Extensive rock anchoring is being used to stabilise a massive escarpment above a power station in Venezuela.
Some 200, between 28m and 43m long rock anchors are being installed on the 50m high slope above the Elitricidad de Caracas Ricardo Zuloga power station on the Caribbean coast, 50km north of Caracas. The 1.2MW thermal power station supplies the capital with electricity.
Rock anchors were originally installed along an 80m long slope in 1974 but with a planned overhaul of a cliff-top substation, it was necessary to carry out remedial work on the badly weathered rock face - a mixture of sedimentary graphite and quartzite rock - and extend it by a further 80m.
Main contractor Ediltauro started work on the 22 month project in October 1998. The firm is using three Atlas Copco BVB25 mobile drilling rigs to install the rock anchors up to 43m into the cliff at the top of the face and up to 28m at the base. Atlas Copco Uniroc rock bit system is being used to drill the 76mm diameter holes at 22degrees, each taking up to four hours depending on ground conditions. The original anchors will be left in the slope, with the new ones installed within 2m.
The firm is also removing the original shotcrete which will be replaced with a 300mm thick layer across the 160m2 face.