Time-dependent deformation behaviour of Queenston shale

Abstract

New methods for simultaneous measurement of three orthogonal strains in time-dependent deformation under several stress systems are described. Results of an extensive series of tests on oriented specimens of Queenston shale, with known magnitude and direction of in situ stress, are reported, together with tests on other shales from southern Ontario. It is found that over the stress range expected in field problems, the swelling behaviour is orthotropic and highly stress dependent. The application of stress in one principal direction not only suppresses the swelling in that direction but also reduces the swelling in the orthogonal directions. A method for representing this strongly nonlinear behaviour is described. Key words: shales, Queenston shale, time-dependent deformation, stress dependency, three-dimensional swelling.