Insight into the effect of dynamic frequency on fracture behaviors of
pre-flawed granite subjected to increasing-amplitude fatigue loading
conditions
Abstract
Real-time acoustic emission (AE) monitoring combined with post-test 3D
computed tomography (CT) technique was employed to reveal the fracture
evolution behaviors of pre-flawed granite. Results show that the dynamic
loading frequency impacts the strength, deformation, AE pattern, rock
bridge fracturing and fatigue life of the granite samples. The
accumulative AE count/energy increases with increasing loading
frequency. In addition, AE spectral frequency analysis reveals six kinds
of crack type, and the proportion of high frequency-high amplitude
signal decreases indicating that large-scaled cracks are prone to form
under high loading frequency. By post-test CT scanning visualization of
the rock bridge segment, the most striking finding is that complex crack
network forms under high loading frequency. The flaws are easy to be
communicated for rock that subjected to low dynamic loading frequency
conditions. It is suggested that deterioration of the rock bridge is
strongly impacted by the dynamic loading frequency.