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 s on Leiyang marble in a stress-controlled manner in order to produce crushed rocks for analysis. We found that cyclic loading between 0.8 and 1.3 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.

中文翻译：

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准静态渐进循环加载下大理石粉碎的微观力学分析


断层损伤区的高度破碎的岩石（即粉状岩石）可能是在同震变形过程中形成的。人们普遍认为这些靠近断层核心的粉状岩石源自高应变率，而距离断层核心数百米（那里普遍存在准静态条件）的粉状岩石的成因仍不清楚。因此，我们以应力控制的方式对耒阳大理岩进行了轴向应变速率~10 s的单轴循环加载实验，以产生碎石进行分析。我们发现，0.8 至 1.3 之间的循环加载可以同时压实大理石中预先存在的裂缝并产生新的裂缝，从而强化和硬化岩石。与在一个周期内单调破裂的参考样品相比，硬化大理石在破裂前形成了更高的裂纹密度和能量密度，从而有利于岩石破碎。我们的结果为现场准静态应变率下粉状大理石的成因提供了合理的解释。