Abstract Based on the split Hopkinson pressure bar (SHPB) laboratory tests, the dynamic mechanical properties and failure mode of sandstone are analyzed, and a SHPB numerical model is established by particle flow code (PFC). The dynamic stress equilibrium, stress wave propagation, stress-strain characteristics and failure mode are analyzed, respectively, which verifies the effectiveness of the model. Then we studied the impact failure process form both mesoscopic cracks and energy point of views. The results show that microcracks are activated in large quantities with the increasing of strain rate. When the crack density reaches a certain degree, the interaction between the cracks can not be ignored. The failure mode gradually changes from local tension–shear damage mode to axial splitting failure mode and then to crushing failure mode. During the impact failure process, the energy is mainly consumed by the generation of the cracks and the friction caused by the slip of the particles, namely, broken dissipation energy. As the impact load increases, the broken dissipation energy density shows the high–speed growth and the low–speed growth stage successively with a double exponential growth pattern. The friction energy increases continually by a certain percentage, which indicates it should be considered during the analysis of fracturing process. Moreover, the dynamic strength and fragmentation degrees are closely related to energy dissipation density.

中文翻译：

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冲击载荷作用下砂岩能量耗散及裂纹演化规律分析

摘要 基于分体式霍普金森压力棒（SHPB）室内试验，分析了砂岩的动态力学特性和破坏模式，采用粒子流编码（PFC）建立了SHPB数值模型。分别对动态应力平衡、应力波传播、应力应变特性和破坏模式进行了分析，验证了模型的有效性。然后我们从细观裂纹和能量的角度研究了冲击破坏过程。结果表明，随着应变速率的增加，微裂纹大量活化。当裂纹密度达到一定程度时，裂纹之间的相互作用就不可忽视。破坏模式逐渐从局部拉剪破坏模式转变为轴向劈裂破坏模式，再到挤压破坏模式。在冲击破坏过程中，能量主要消耗在裂纹的产生和颗粒滑移引起的摩擦上，即破碎耗散能。随着冲击载荷的增加，破碎耗散能量密度依次呈现高速增长和低速增长阶段，呈双指数增长模式。摩擦能以一定的百分比不断增加，说明在压裂过程分析中应予以考虑。此外，动态强度和破碎度与能量耗散密度密切相关。破碎耗散能量密度依次呈现高速增长和低速增长阶段，呈双指数增长模式。摩擦能以一定的百分比不断增加，说明在压裂过程分析中应予以考虑。此外，动态强度和破碎度与能量耗散密度密切相关。破碎耗散能量密度依次呈现高速增长和低速增长阶段，呈双指数增长模式。摩擦能以一定的百分比不断增加，说明在压裂过程分析中应予以考虑。此外，动态强度和破碎度与能量耗散密度密切相关。