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Marble
Strengthening
Pulverization
Progressive cyclic loading
Abstract:
Highly fragmented rocks (i.e., pulverized rocks) in the fault damage zone presumably develop during co-seismic deformation processes. These pulverized rocks close to the fault core are generally thought to originate from high strain rates, whereas the genesis of pulverized rocks that can be found several hundred meters away from the fault core – where quasi-static conditions prevail – remains unclear. We thus conducted uniaxial cyclic loading experiments with axial strain rate of ∼10−3 s−1 on Leiyang marble in a stress-controlled manner in order to produce crushed rocks for analysis. We found that cyclic loading between 0.8 σc and 1.3 σc can simultaneously compact pre-existing cracks and generated new cracks in marble, which strengthened and stiffened the rock. The stiffened marble developed a higher crack density and energy density before rupture, thereby facilitating rock fragmentation compared with the reference sample, which was fractured monotonically in one cycle. Our results provide a plausible explanation for the genesis of pulverized marble at quasi-static strain rate in the field.
