
E1001A-171107
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10.3 ROCK
The TEXAM
e
can be used in rock, but in very soft ones only. And special precautions
regarding the volume calibration must then be taken. Two calibrations up to 10,000 kPa
must be run just prior from lowering the probe in the borehole. Then, the test itself should
be done following the stress controlled method in order to get more points for modulus
determination. When these precautions are taken, the user can expect to obtain
representative moduli up to about 2 GPa. The repeatability of the system expansion
coefficients obtained during calibrations is an indicator of the reliability of the obtained
moduli. Size of the borehole will also affect the results. The borehole diameter should be
as close as possible to the one of the calibration steel tube.
10.4 DRY BOREHOLE
Past a certain depth (about 5 m), the use of the TEXAM
e
is possible only if the hole is
filled with fluid. The resistance of the membrane being small and due to the effect of the
water column inside the equipment, the probe will start to expand quickly if it is lowered
in a dry hole.
10.5 DEEP BOREHOLE
The TEXAM
e
can be used for performing tests at great depth (over 100 m) provided the
borehole is filled with fluid.
11
RECOMMENDATIONS
Do not wait until the last minute to verify and calibrate the equipment
On site, keep different sizes of drilling bits and two complete probes to speed up
testing. On remote sites, bring a bench vise for membrane replacement.
Check data as test proceeds.
The shelf life of sheaths is 2 years. These must be used within this timeframe.
Keep the equipment dry and clean.
12
MAINTENANCE
12.1 PREVENTING THE EQUIPMENT FROM RUSTING
It is very important not to keep the equipment saturated for extended period of time.
Otherwise it will start rusting. When a testing campaign is over, the pressuremeter must
be desaturated as per sections 4.1 to 4.3, with the difference that the free end of the
saturation tubings must remain out of the water during the entire process. This way, the
unit will be ‘saturated with air’. Also, disassemble the probe to keep it dry.
When a testing campaign is over, also make sure no water of humidity has accumulated
in the control box. For doing so, unscrew the four screws (f) of the mounting panel. Use
two of the four support columns (i) for lifting the panel.
Warning : avoid any shocks
between the internal circuit and the box when lifting the panel. For avoiding that, lift
the panel slowly and vertically.