Geokon 6300, Instruction Manual, Page: 12 / 24

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This assembly is now lowered into the borehole, using the safety cable, with the upper
assembly fixed wheel aligned in the so-called A+ direction. It is customary (and
recommended) to point the A+ direction in the same direction as the anticipated
movement, i.e., towards the excavation being monitored or down-slope in the case of
slope stability applications. Be sure that the lower wheel assembly and swivel are also
aligned this way.
While holding the assembly at the top of the casing, using either the safety cable or
vice grips on the tubing, the next segment with sensors, wheels and swivel are attached
and lowered in the same orientation. The system can become quite heavy and a clamp
of some sort may need to be used to hold the rods in place while being assembled. The
use of a winch to hold the safety cable can be a help. Note that the longer cables are on
reels to facilitate handling. Something like two little saw horses (or even folding chairs)
with a broom stick across them to act as an axle will allow the cable to spool off as
needed and provide a storage point for the rest of the cable.
The cables from the lower sensors should be taped or tie-wrapped to the assembly at
intervals to support them as the system is built up and lowered down the borehole.
Continue to add gauge tubing, sensors and wheel assemblies until the last sensor has
been attached to the upper wheel assembly, which is pre-assembled to the top
suspension (Figure 7). The Top suspension can then be lowered into position on the
casing. It is important that the end of the casing be cut square to prevent any side
pressure on the upper sensor wheel assembly.
Figure 7 - Top Suspension
After the sensor string has been lowered into position, the safety cable can be tied off around the
top of the casing and the signal cables can be run to the readout location and terminated or
otherwise fixed. Readings should be taken immediately after installation, but it is recommended
that the system be allowed to stabilize for a few hours before recording zero conditions.
For IPI strings that are going to measure only across a subsurface zone of interest and will not
reach the surface, the cross-piece of the top suspension is omitted and the IPI string is suspended
at the proper depth by a length of aircraft cable, attached to the eyebolt, and tied off at the top of
the casing.