GROUND SUPPORT
through severely weathered ground conditions
and developments through faults as part of the
mining development cycle.
A particular project worth noting was the
development of a new adit system for a mine
situated in the South African Eastern Limb of the
Bushveld Igneous Complex. This project required
the need to assist the mine with the initial
development of 110 m, in each adit, through highly
weathered ground conditions. The ground
conditions did not suit the use of conventional
bolting and ground support techniques. In its
initial assessment Weber suggested its Marisil
range of resins. The resins have the following
characteristics:
n Fast reaction times with setting happening
within 2 mins 30 seconds
n Excellent bond strengths and flexibility to
handle blasting concussions
n Chemical reaction is not affected by the
presence of moisture and water
n Marisil E is able to penetrate cracks and
fractures up to 50 microns, with excellent
migration through fractured and weathered
ground conditions
n Marisil Thixo is an ideal bolting resin, easy to
install, instant gelling properties, and with very
early load transfer capacity
“By trialling and implementing the use of our
Marisil E and Marisil thixotropic resins we were
able to assist the mine with the development,
safely and economically. With the use of our resins
alongside well known Self Drilling Anchors, we
were able to assist the mine with the completion
of approximately 800 m of roadway development
in seven months.”
Conventionally these ground conditions would
have been supported using steel set installations
and sprayed concrete. With this methodology
planned excavations must be increased to
incorporate the steel set installations, cavity filling
is a requirement behind the installed sets before
and sprayed concrete application can be done.
This increases the costs significantly due to
increase material requirements, increased
excavation requirements and extended project
programs.
“In addition to the good ground support
achieved with the use of our Marisil resins, we had
added benefits of sealing of water ingress as well
as increased blasting performance with the
consolidated ground. These techniques were also
adapted to assist the mine with the preconsolidation
of a ventilation raise bored shaft,
which was also developed through the highly
weathered norite formations which are dominant
in this area.”
Weber Mining Offices are established in France,
Poland, Turkey, Australia, Mexico and South Africa
and are able to assist mines globally with chemical
ground support (pumpable resins and foams).
JENNMAR's multipoint anchor tech
JENNMAR introduced its multipoint anchor (MPA)
technology in the western US region three years
ago. Ground support product development in the
US has been rapid working in conjunction with
major gold miners there and the ground
conditions that JENNMAR has encountered in the
Northern Nevada region have been extremely
poor. The MPA is a hollow core self-drilling bolt.
The system pumps resin
through the bolt,
encapsulating the bolt and
filling the hole. The miners
do not need to remove the
bolt to install a resin
cartridge, which in these
mines in most cases would
have allowed the hole to
collapse. Along with the
use of JENNMAR MPA,
JENNMAR also introduced
its J-LOK P Pumpable Resin
system. J-LOK P™ is an
innovative resin delivery
system for underground
mining & tunnelling
applications. The system consists of a twocomponent,
pumpable, polyester resin and a
specialised pump that delivers the resin directly to
the bolt hole. Developed to improve the
productivity, safety and reliability of ground
support installations, J-LOK P can be used for a
wide range of ground support products including
solid steel rebar, hollow core bolts and cable
tendons
Geobrugg offers last line of defence
with MINAX
Mining is getting deeper, and rockbursts are a
growing risk in underground excavations around
the world. Especially in mining tunnels, when in
search of the mineral strata, tunnels are deepened
more and more, until reaching depths greater than
1,000 m and more. However, seismicity events and
associated rockburst can occur even at lower
depths. Traditional support and reinforcement
systems such as shotcrete reinforced with electrowelded
mesh or fibrecrete used in underground
mining are limited in their capability against
dynamic loads. The development of diamondshaped
lightweight steel wire meshes MINAX ® of
very high strength in recent years has offered
alternative design solutions. In order to fully
understand the behaviour and capacity of various
ground support systems using these MINAX ®
meshes, the Swiss company Geobrugg says it has
carried out many full-scale dynamic tests in its
own test centre in collaboration with universities
and mines from all parts of the world.
The company told IM: “The need to increase
the energy dissipation capacity in the support
system designs of different mines has been
present for many years ago. With this goal in
mind, systematic studies have been carried out,
aiming to improve the performance of the single
elements and the complete reinforcement
systems. In addition, the development of diamond
shaped lightweight steel wire membranes of very
high-tensile strength, in recent years, has given a
great boost to this trend. These powerful flexible
The JENNMAR J-Lok P™ Pumpable Resin
system is applicable to mechanised bolters and
skid mounted systems
solutions combined with suitable anchors have
undoubtedly been a huge step towards solving
situations where protection against dynamic load
is imperative.”
In order to prove the suitability of such support
systems with high-tensile steel mesh and bolts
and to analyse the bearing behaviour of them, a
large-scale test centre was commissioned in
Geobrugg full-scale test rig in Walenstadt,
Switzerland
50 International Mining | JULY/AUGUST 2020