Stiff Dilatometer

Over the past three decades, borehole dilatometers have come into common use for evaluating load-deformation properties of rock masses in situ [l-7]. Borehole dilatometer testing augments other in situ deformability measurement methods, such as the plate loading and radial jacking tests. The ISRM Commission on Testing methods has sponsored two suggested methods that are aimed to help achieve some measure of standardization of use without inhibiting the development and improvement of techniques. The first of the two suggested methods, addressing borehole tests with flexible dilatometers, has already been published [S]. This document, the second of the two suggested methods, covers applications of relatively stiff dilatometers that are commercially available and in common use.