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| A
switch to Secoroc rock drilling tools saved time and money at the
huge Immigrantes Highway tunnel project. |
[Brazil]
Nice
surprises at
Imigrantes tunnels
When
contractors working on the Imigrantes Highway between São Paulo
and Santos began excavating the 8,230 m of tunnels required, they found
they needed better equipment to tackle the hardness and abrasiveness of
the granite/gneiss.
"When we started, we used conventional rods and shank adapters with
R32 threads from different suppliers," recalls Bento Manoel Silva,
General Tunnel Supervisor. "But due to the high power of the Atlas
Copco COP 1838 rock drills the rods deflected when collaring the hole,
which generated deviation, and both the rods and shank adapters broke."
Instead, it was decided to try Atlas Copco Secoroc tools with R35 threads,
hexagonal rods and ballistic button bits. "These surprised us,"
he says. "The tools became rounded without breaking and reached the
end of their lives only when the threads had worn out. Also, the ballistic
bits gave us a penetration rate 20% faster than the spherical, R32 button
bits we had previously."
As a result, the job was completed 30 days ahead of schedule. |
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