Dynamic mechanical behaviors of naturally fractured granite subjected to
multi-level uniaxial fatigue loads: Insights from fracture and energy
evolution analysis
Abstract
Multi-level uniaxial fatigue loading experiments were carried out to
reveal the fracture and energy evolution of naturally fractured granite
using stress strain descriptions and post-test computed tomography (CT)
technique. Results reveal the influence of natural fracture on
mechanical properties of granite, regarding the fatigue lifetime,
fatigue deformation characteristics, fatigue damage, energy evolution
and fatigue failure pattern. Volumetric and shear processes caused by
the sliding and shearing along the natural fracture control the whole
failure process. The energy dissipation and releases characteristics are
strongly impacted by natural fractures. The elastic energy and
dissipated energy both decrease with increasing natural fracture volume,
growth of the dissipated energy becomes faster for rock near to failure.
Post-test CT scanning reveals the crack pattern, and failure changes
from tensile mode to shear mode with the increasing natural fracture
volume. It is proved that the dissipated energy is mainly used to
activate the pre-existing natural fractures.