Borehole Dilatometer

The dilatometer test is a loading test run inside a borehole with a radially expandable cylindrical probe. The PROBEX determines the deformations by measuring the total volume change of the probe. This method is the same well-proven method used with the pressuremeter. It provides a mean modulus value of a large volume of rock, contrary to the use of callipered probes which can be affected by local heterogeneities. The volume changes of the probe are measured by monitoring the displacement of a piston. This confi guration eliminates the parasitic expansion of the tubing and pumping system.