8
Roof/Rib Load Cell Installation Hazards
Roof/rib bolt load cells are devices containing strain gauges
used to measure the load on rock bolts (Minoski et al.,
2024). Hazard associated with the installation of these load
cells include working around heavy equipment, manual
handling, and pinch points. A roof bolting machine is uti-
lized to install the load cell. Similar to the installation of
BPCs and extensometers, working in close proximity to a
roof bolting machine will present the same hazards to
researchers and operators. Part of the installation of cable
bolt load cells involves sandwiching a 1” plate, a load cell,
another 1” plate, and a roof bolt plate on a roof bolt (See
Figure 13). The hazard for researchers and operators com-
pleting this task is pinch points and hand injuries.
Because the installation of roof/rib bolt load cells
requires a hands-on approach as the bolt is being installed,
there is the potential for significant injuries. Recently, 6
rib bolt load cells were installed by NIOSH researchers
(Rashed et al., 2021). The employees tasked with this install
wore metacarpal gloves and no injuries occurred.
Hollow Inclusion (HI) Cell Installation Hazards
Hollow inclusion (HI) Cells (See Figure 14) are instru-
mentation used for three-dimensional stress measurements
in rock and other material (Minoski et al., 2024). The
installation process requires a collaborative effort between
researchers and operators. While researchers handle instru-
ment preparation and the actual installation, operators uti-
lize a roof bolting machine to drill holes to a predetermined
depth for the HI Cell.
Drilling these holes involves constant addition and
subtraction of drill steel. This activity presents risks such as
pinch points, hand injuries, and manual handling injuries
Figure 13. Example of an installed roof bolt load cell
to personnel. As highlighted earlier, working adjacent to
the roof bolting machine comes with inherent dangers.
Once drilling is completed, the next phase is the prepa-
ration of the HI Cell instrumentation.
This involves adding a corrosive epoxy resin, which can
irritate the skin, and cleaning the drilled hole using inser-
tion rods. The cleaning process poses hazards for research-
ers, including potential hand injuries and pinch points.
After the holes are cleaned and the instrumentation is
ready, the HI Cell is installed. This step requires the use of
insertion rods to set the HI Cell at the maximum drilled
depth. The manual effort to push the HI Cell vertically
into the roof can lead to muscle strains. Additionally, as
mentioned earlier, researchers face risks of pinch points and
hand injuries during this phase.
Securing the HI Cell is the final step. Depending on
the mining height, researchers might need a ladder to reach
the roof and secure the insertion rod, ensuring the HI Cell
sets properly. Using a ladder introduces risks such as falls,
being in the line of fire, and potential misuse of the ladder,
all of which can result in injuries to the researchers.
Perhaps the most intensive HI Cell installation occurred
at a longwall mine in Southwestern Virginia (Klemetti et
al., 2019). Here, NIOSH researchers attempted to install
6 HI Cells at various angles into the roof over the pillars.
The shallower the angle, the more difficult these were to
drill. This resulted in broken drill steel, water swivels, and
worn bits. This required researchers to add and remove
steel to a very heavy drill string up to 30 ft. into the roof.
This installation was completed with no injuries reported.
However, the weight of such a long drill string, especially
at the steeper angles was problematic from a material han-
dling standpoint.
Figure 14. Example of a Hollow Inclusion (HI) Cell
Roof/Rib Load Cell Installation Hazards
Roof/rib bolt load cells are devices containing strain gauges
used to measure the load on rock bolts (Minoski et al.,
2024). Hazard associated with the installation of these load
cells include working around heavy equipment, manual
handling, and pinch points. A roof bolting machine is uti-
lized to install the load cell. Similar to the installation of
BPCs and extensometers, working in close proximity to a
roof bolting machine will present the same hazards to
researchers and operators. Part of the installation of cable
bolt load cells involves sandwiching a 1” plate, a load cell,
another 1” plate, and a roof bolt plate on a roof bolt (See
Figure 13). The hazard for researchers and operators com-
pleting this task is pinch points and hand injuries.
Because the installation of roof/rib bolt load cells
requires a hands-on approach as the bolt is being installed,
there is the potential for significant injuries. Recently, 6
rib bolt load cells were installed by NIOSH researchers
(Rashed et al., 2021). The employees tasked with this install
wore metacarpal gloves and no injuries occurred.
Hollow Inclusion (HI) Cell Installation Hazards
Hollow inclusion (HI) Cells (See Figure 14) are instru-
mentation used for three-dimensional stress measurements
in rock and other material (Minoski et al., 2024). The
installation process requires a collaborative effort between
researchers and operators. While researchers handle instru-
ment preparation and the actual installation, operators uti-
lize a roof bolting machine to drill holes to a predetermined
depth for the HI Cell.
Drilling these holes involves constant addition and
subtraction of drill steel. This activity presents risks such as
pinch points, hand injuries, and manual handling injuries
Figure 13. Example of an installed roof bolt load cell
to personnel. As highlighted earlier, working adjacent to
the roof bolting machine comes with inherent dangers.
Once drilling is completed, the next phase is the prepa-
ration of the HI Cell instrumentation.
This involves adding a corrosive epoxy resin, which can
irritate the skin, and cleaning the drilled hole using inser-
tion rods. The cleaning process poses hazards for research-
ers, including potential hand injuries and pinch points.
After the holes are cleaned and the instrumentation is
ready, the HI Cell is installed. This step requires the use of
insertion rods to set the HI Cell at the maximum drilled
depth. The manual effort to push the HI Cell vertically
into the roof can lead to muscle strains. Additionally, as
mentioned earlier, researchers face risks of pinch points and
hand injuries during this phase.
Securing the HI Cell is the final step. Depending on
the mining height, researchers might need a ladder to reach
the roof and secure the insertion rod, ensuring the HI Cell
sets properly. Using a ladder introduces risks such as falls,
being in the line of fire, and potential misuse of the ladder,
all of which can result in injuries to the researchers.
Perhaps the most intensive HI Cell installation occurred
at a longwall mine in Southwestern Virginia (Klemetti et
al., 2019). Here, NIOSH researchers attempted to install
6 HI Cells at various angles into the roof over the pillars.
The shallower the angle, the more difficult these were to
drill. This resulted in broken drill steel, water swivels, and
worn bits. This required researchers to add and remove
steel to a very heavy drill string up to 30 ft. into the roof.
This installation was completed with no injuries reported.
However, the weight of such a long drill string, especially
at the steeper angles was problematic from a material han-
dling standpoint.
Figure 14. Example of a Hollow Inclusion (HI) Cell