9
in 50KIP and 100KIP capacity with a 1” passthrough.
The installation procedures for a roof bolt load cell are as
follows:
• Pre-drill a hole to the required depth and size to spec-
ification of the bolt being installed/monitored.
• Assemble onto bolt in the order of:
– 1” thick washer
– GEOKON Load Cell
– 1” thick washer
– Roof bolt plate.
• Using the bolting machine, push assembly into the
hole.
• For mechanical anchor bolts, spin carefully, then
tighten to specification.
• For resin bolts, allow an inch or so of space between
the load-cell assembly and the roof line. (This will
allow the bolt to be spun freely as resin is mixed with-
out damaging the load cell). Spin the bolt the desired
amount, then apply force to set (see Figure 16).
Standing Support Load Cell
The standing support load cell offers insight on real-world
loading conditions being applied to standing support dur-
ing long-term and active mining studies. This combined
with a roof-to-floor extensometer (see Figure 3) can mea-
sure how well a support is performing as well as the overall
entry stability (Klemetti et al., 2018). The construction of
the standing support load cell consists of two seam-welded
sheets of steel in the shape of a circle or square with vary-
ing dimensions to accommodate the standing support
being used. There are welded bungs providing a fill port
and a pressure transducer port. The bladder is typically pre-
formed between two platens using pressurized water to a
thickness of one inch, then calibrated under varying loads
and tested for leaks prior to installation in the field. The
installation procedure for standing support load cells are
as follows:
• Installation of the standing support load cell requires
a solid contact point to the bladder faces.
• This is achieved by using a stacked configuration of
crib blocks and plywood on the top and bottom of
the bladder.
• If installing underneath the standing support (i.e.,
pumpable supports), orient the pressure transducer
up, provide a solid and level base using crib blocks
on the mine floor, followed by a ¾” plywood, the
load cell bladder, ¾” plywood, and another layer of
crib blocks.
• If installing on top of the standing support (i.e.,
cans/posts/cribs), orient the pressure transducer
down, provide a solid and level base using crib blocks
on top of the support, followed by ¾” plywood, the
load cell bladder, another sheet of ¾” plywood, and
another row of crib blocks. Use wedges as needed to
tightly secure against the mine roof.
• Connect the data cable and take initial readings.
The preceding sections have provided a comprehensive
overview of the ground-control instrumentation used by
NIOSH researchers at NIOSH. While many of the instru-
mentation devices on the market have some sort of manual
readout, an appropriate data acquisition system is generally
Figure 15. Example of a GEOKON Model 3000 load cell
(after GEOKON, 2020)
Figure 16. Completed installation of load cell on a cable
bolt using the NIOSH installation procedure
in 50KIP and 100KIP capacity with a 1” passthrough.
The installation procedures for a roof bolt load cell are as
follows:
• Pre-drill a hole to the required depth and size to spec-
ification of the bolt being installed/monitored.
• Assemble onto bolt in the order of:
– 1” thick washer
– GEOKON Load Cell
– 1” thick washer
– Roof bolt plate.
• Using the bolting machine, push assembly into the
hole.
• For mechanical anchor bolts, spin carefully, then
tighten to specification.
• For resin bolts, allow an inch or so of space between
the load-cell assembly and the roof line. (This will
allow the bolt to be spun freely as resin is mixed with-
out damaging the load cell). Spin the bolt the desired
amount, then apply force to set (see Figure 16).
Standing Support Load Cell
The standing support load cell offers insight on real-world
loading conditions being applied to standing support dur-
ing long-term and active mining studies. This combined
with a roof-to-floor extensometer (see Figure 3) can mea-
sure how well a support is performing as well as the overall
entry stability (Klemetti et al., 2018). The construction of
the standing support load cell consists of two seam-welded
sheets of steel in the shape of a circle or square with vary-
ing dimensions to accommodate the standing support
being used. There are welded bungs providing a fill port
and a pressure transducer port. The bladder is typically pre-
formed between two platens using pressurized water to a
thickness of one inch, then calibrated under varying loads
and tested for leaks prior to installation in the field. The
installation procedure for standing support load cells are
as follows:
• Installation of the standing support load cell requires
a solid contact point to the bladder faces.
• This is achieved by using a stacked configuration of
crib blocks and plywood on the top and bottom of
the bladder.
• If installing underneath the standing support (i.e.,
pumpable supports), orient the pressure transducer
up, provide a solid and level base using crib blocks
on the mine floor, followed by a ¾” plywood, the
load cell bladder, ¾” plywood, and another layer of
crib blocks.
• If installing on top of the standing support (i.e.,
cans/posts/cribs), orient the pressure transducer
down, provide a solid and level base using crib blocks
on top of the support, followed by ¾” plywood, the
load cell bladder, another sheet of ¾” plywood, and
another row of crib blocks. Use wedges as needed to
tightly secure against the mine roof.
• Connect the data cable and take initial readings.
The preceding sections have provided a comprehensive
overview of the ground-control instrumentation used by
NIOSH researchers at NIOSH. While many of the instru-
mentation devices on the market have some sort of manual
readout, an appropriate data acquisition system is generally
Figure 15. Example of a GEOKON Model 3000 load cell
(after GEOKON, 2020)
Figure 16. Completed installation of load cell on a cable
bolt using the NIOSH installation procedure