#64 -NITREX - LAKE MEAD underwater rock blasting excavation SPOT

Описание: Lake Mead, Nevada USA, No.3 Intake Las Vegas, 2008 - 2011

Underwater blasting
Lake Mead, the largest man-made reservoir in the United States, is located about 30 miles southeast of Las Vegas,
Nevada. For the construction of Lake Mead third water intake, which is entirely placed underground, an underwater excavation was needed at a depth of 100 m (330 ft): a large surface had to be deepened by 20 m (66 ft) in basalt.
New technology that would fit the special circumstances of this job was not available, so the old one, the "brutal", not-precise but effective technology of the shaped-demolition-charges was chosen.
It was then found that no shaped charge existed that fit the underwater specifications of this job so a new one had to be conceived, as well as its deployment system and technique, monitoring and survey procedures. For this an international task of experts was put together.
Basaltic stone is strong and resilient. It has a high resistance to metallic jet penetration, close to that of ceramic which is therefore used in the defense industry on steel tank armor, to add extra protection to the penetration of the grenade's jet. High energy of the jet produced by the detonation of the charge was required for basaltic stone and, for this, an adequate liner material, the best quality of execution, right form and mass as well as in adequate
stand-off in air were needed. To keep the charge stand-off water free at that depth, a specially fitted shell had to
be coupled to the charge, ballasted to prevent floating. This was one of the "rings" of a chain of "problems to solved" both in the design phase and also with work in progress, targeting to optimization of the production technology,
of the product itself and of the method of use. Since large quantities were needed, a solution targeted to minimize environmental impact was adopted. Biodegradable materials were chosen to reduce from one hundred years to five, the bio-degradation time of the plastic residual from the charge canister.

Lake Mead, Nevada USA, III opera di presa per l'acquedotto di Las Vegas, 2008 - 2011
Sbancamento subacqueo con esplosivi da -100 a -120 m di un ammasso basaltico. Progettazione di una
carica cava e di un robot per la deposizione subacquea di campi di cariche cave.