20
E10037-180424
PROBEX
2.7
TESTING PROCEDURE
STEP 1. Turn on the readout unit and wait long enough for the probe to reach temperature
equilibrium with the surrounding rock (15 min typ.)
STEP 2. The dual-action piston must be in the completely retracted position.
STEP 3. Set the manual pump control valve handle to position 1, ensure that the cyclic test
valve is open.
STEP 4. Load the rock mass by stress control steps, typically 10 increments of 3 MPa up
to 30 MPa. At each step, pressure and volume are recorded after a one-minute
stabilization period for test duration of about 10 minutes. These steps can be
smaller when working in a very soft rock, or when the borehole is very large.
STEP 5. If an unloading phase is required, close the cyclic valve and strike the handle of
the pump valve from position 1 to 2. Open slowly the cyclic valve for reducing
pressure. For increasing the pressure, strike the handle of the pump back in the
position 1, and re-apply some pressure while opening the cyclic valve. It is
suggested to practice cyclic loading with the probe in the calibration tube before
attempting it during a test.
STEP 6. When the test is complete, deflate the probe by pumping with the control valve
handle in position 2. The dual-action piston will be fully retracted when the readout
shows a zero reading.
STEP 7. Withdraw the PROBEX from the hole or move it to the next testing position. Note
that tests are normally carried out from lowest testing elevation upward.
Standard
spacing between tests is 1.5 m. Inflatable membrane should not be located closer
than 0.5 m from the top of the rock or from the bottom of borehole.
Typical PROBEX Calibration and Test Results from the PROBEX
