Progressive damage of Hawkesbury sandstone subjected to systematic cyclic loading

Abstract

An experimental investigation was carried out on the Hawkesbury sandstone to identify and predict the change in mechanical properties of the rock during uniaxial and triaxial cyclic compressive testing. Cyclic tests were completed at different stress levels and unloading amplitudes. Damage increased with an increase in unloading stress level and unloading amplitude. Results indicate that leading up to unstable crack propagation, approximately 65 per cent of the cumulative axial strain (measured at the peak of each cycle) occurs prior to the critical damage point with a rapid increase after this point. The rate at which strain accumulated after the critical damage point is dependent on the stress level at unloading and unloading amplitude. A preliminary damage model was proposed to predict reduction in the peak strength and tangent Young’s modulus of a rock due to cyclic loading. For future development of this work, a methodology to conduct cyclic loading tests was proposed.