PROBEX Borehole Dilatometer: Rugged, Safe & Very high capacity

How it works

The dilatometer test is a loading test run inside a borehole with a radially expandable cylindrical probe, using the same well-proven method as the pressuremeter test. The PROBEX determines deformation by measuring the total volume change of the probe, which provides a mean modulus value across a large volume of rock, unlike callipered probes that can be affected by local heterogeneities.

Volume changes are measured by monitoring the displacement of a piston, which eliminates the parasitic expansion of the tubing and pumping system.

What's included

An inflatable membrane mounted on a steel core; a hydraulic module with a dual piston and cylinder assembly to inflate and deflate the membrane; a measuring module containing a linear transducer that monitors the injected volume; hydraulic and electrical lead lines; a hydraulic hand pump and pressure gauge; a digital readout; and a pressure transducer.

Test & interpretation

Leads are threaded inside a B-size casing (or equivalent) used to lower the probe to test depth. Tests are stress-controlled: pressure increments are applied in stages using the hand pump. Probe compressibility is determined by calibration tests run in a thick-wall cylinder, and the data is interpreted using the same method used for pressuremeter data, based on Lame's equations, yielding a mean modulus of deformation for the rock mass tested.