This paper presents an experimental investigation of the fatigue properties of limestone subjected to triaxial compression with\naxial cyclic loading. Tests were conducted on intact limestone samples with a loading frequency of 0.5 Hz and a confining pressure\nof 10 MPa. The test results show the following five points. (1) Under triaxial conditions, the axial and circumferential deformations\nat the failure point induced by cyclic loading are slightly larger than the corresponding deformations at the peak stress achieved by\nconventional compression tests. (2) The first level cyclic loading process has a strong influence on rock deformation in the primary\nphase during subsequent level cyclic loading. A smaller difference in stress amplitude between the two loading stress levels leads to\nless deformation during the latter. (3) Circumferential and volumetric changes are more sensitive to fatigue failure in terms of\ndeformation and strain rate than axial changes. (4) The three phases of dissipated energy evolution are consistent with a sampleâ??s\ndeformation such that the energy dissipation characteristics reflect the fatigue damage evolution process. (5) A new damage\nformula is proposed that can concisely describe a rockâ??s zero-cycle damage and damage evolution.
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