ROCK REINFORCEMENT
MacLean Engineering believes face bolting on
the 975 Scissor Bolter answers the call for a
more efficient way to provide a safer
environment for miners working at the face
The El Teniente mine in Chile is facing
significant challenges in terms of seismicity. It
has to adapt its ground support systems to new
high demands in terms of energy absorption and
the way the systems are installed inside the
tunnels. This innovative ground support system
using Geobrugg high-tensile chain-link mesh
called MINAX ® provides a solution for high
energy demands up to 60 kJ.
The tests have shown that the special design,
developed by the geotechnical department of
this division of Codelco, is highly suitable for
protection and support in underground
24 International Mining | AUGUST 2019
excavations in areas with
potential for extreme
rockburst. The series of
large-scale tests allowed the
verification of the dynamic
ground support system for El
Teniente mine.
“This also clearly
demonstrated that this type
of design, with high-tensile
chain-link mesh, allows high
energy absorption of the
dynamic loads from periodic
rockburst, without any
maintenance requirement. Which is both
fundamental for guaranteeing miners’ safety and
essential to increase the productivity of mining
development ultimately.”
are easily installed with current mining
equipment. A mesh testing machine was built by
Jennmar, measuring load and displacement
accurately using a data acquisition system,
which pushes against the restrained mesh
module. A testing program comparing
conventional surface support were tested for
baseline results. New module designs
incorporating existing mesh types and new
design concepts were manufactured and tested
using the same test method. Based on these
results, two high capacity mesh modules
achieving greater than 20 t were produced.
Improving sprayed concrete results
through automation
Jennmar ups mesh module capacity Normet says spraying concrete has become more
efficient and safer with its innovative 3D laser
scanning technology SmartScan which combines
the latest sensor technology with successful
Steel wire weld mesh is a common industry
standard surface support used in underground
mining traditionally installed with mining drills
during the bolting cycle. As underground mining
depth and stress increase, mining methods and
their sequences at these depths place challenges
on conventional surface support options. These
challenges Jennmar argues have provided a need
for high capacity surface support options that
improve development efficiency, reduce the need
for secondary ground support installation and shotcrete equipment and applications from
Normet. “SmartScan is designed for the dusty
and harsh underground construction
environment. Placed inside a robust stainless
box mounted in front of the concrete spraying
machine, the enclosure needs only to be opened
for starting the scan via the touchscreen.”
The IP65 rated laser scans the face in 50 m
maximum range, 0 to 180 degree horizontal and -
60 to +140 degree vertical angle before spraying.
With a second scan after spraying concrete, the