Inclinometer Cable Frequently Asked Questions
1. Can the cable become elongated or abridged ?
This
is an issue that is very rarely experienced. Any elongation of the
cable is down to how each individual uses the inclinometer. The action
of the probe accelerating and stopping suddenly can cause an inertia
effect on the cable and markers making what can be described as a
hammering effect.
Tip:
We recommend placing the inclinometer into each depth on the cable
gate rather than dropping it to stop the amount of cable elongation.
2. Due to hammering effect the cable can expand but how about the contraction of the spaces between cable markers?
The
contraction of the spaces between markers can also occur because of
the hammering effect as previously described. If certain cable markers
are dropped harder or from a higher distance than the cable marker above
both the distance between the two markers will decrease. This does not
necessarily mean that the cable has contracted itself, just that the
distance between the two markers has reduced.
3.
Once any elongation has occurred, in your experience, are we right to
assume more elongation will occur? Due to perhaps a wear and tear of
the cable?
This is hard to say whether further elongation will occur or not. If
the user takes care of the inclinometer when taking readings as we have
mentioned above, there is no reason to believe that further elongation
will occur.
4. What is the life span of the cable?
It is hard to quantify the life span of a cable, as this is down to the
amount of use of the inclinometer, how the inclinometer is used and
whether the inclinometer is looked after. We can say that any
degradation of the cable is down to use and the user rather than age.
5. Will cable elongation affect our reading ?
The
elongation of the cable will only effect the readings if it has
occurred during the time since the original set of readings have been
taken. If it has not occurred during this time,i.e. before the readings
were taken or since the last set of readings, then it will not impact
on your results
6. What
is the tolerance as a definition of what should be the limits for a
cable to stop using the inclinometer to measure displacement
(eg: If a
75m length elongated / abridged by more than 25mm is it advisable to
use at site?).
In that case what shall be the remedial measure to be
implemented ?
This
is a hard question for us to answer, a 25mm elongation would result in
a difference at the bottom of the borehole however this would decrease
as the probe is brought up through the borehole if the stretching is
even at every depth. Figure 1 shows a very exaggerated example of what
would happen if a cable has elongated since the measurements began. As
you can see you would be measuring a different area of the borehole and
as a result would not match up to your previous readings. The only way
to remedy this in the long term would be to replace the elongated cable
with a new cable. If this work was done to the unit, we would
recommend starting a fresh with the new cable, as the new cable would
now give the true shape of the borehole and would not match up to the
previous readings taken at inaccurate depths.
Figure 1. Example of an elongated cable
If this has not solved your issue please submit a ticket through the support site.