To investigate the stress‐confinement effect on the dynamic crack propagation and energy evolution characteristics of heterogeneous granite under impact loading, a three‐dimensional equivalent grain‐based model (3D‐GBM) and FLAC3D‐PFC3D coupled modeling technique was used to establish a numerical model of a full‐scale true triaxial Hopkinson test system. The results indicate that: (1) A rate‐effect model of the dynamic strength enhancement factor for heterogeneous rocks under multiaxial static and dynamic combined loading was constructed, with lateral stress confinement enhancing the sensitivity of dynamic strength to the strain rate. (2) Axial stress reduces the crack initiation stress ratio (σci/σd) and damage stress threshold ratio (σcd/σd), reducing the time to their onset, while lateral stress has the opposite effect. (3) Lateral stress confinement helps dynamically adjust the types of microcracks within the rock, restricts the relative slip friction between particles, and decreases the kinetic energy of failure. (4) At approximately the same strain rate, the strain energy and slip friction energy sequentially increase under uniaxial, biaxial, and triaxial stress confinement. The mutual slip friction and movement between rock particles are more intense under biaxial stress confinement compared to uniaxial conditions.

中文翻译：

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应力约束对冲击载荷作用下非均质花岗岩动态力学性能的影响：实验和数值模拟


为研究应力约束对冲击载荷作用下非均质花岗岩动态裂纹扩展和能量演化特性的影响，采用三维等效晶粒模型 （3D-GBM） 和 FLAC3D-PFC3D 耦合建模技术建立了全尺寸真三轴霍普金森试验系统的数值模型。结果表明：（1）构建了多轴静动联合载荷下非均质岩石动态强度增强因子的速率效应模型，其中侧向应力限制增强了动态强度对应变速率的敏感性。（2） 轴向应力降低了裂纹起裂应力比 （σci/σd） 和损伤应力阈值比 （σcd/σd），缩短了它们发生的时间，而侧向应力则具有相反的效果。（3） 侧向应力约束有助于动态调整岩石内部微裂纹的类型，限制颗粒之间的相对滑移摩擦，降低破坏动能。（4） 在大致相同的应变速率下，在单轴、双轴和三轴应力约束下，应变能和滑移摩擦能依次增加。与单轴条件相比，在双轴应力约束下，岩石颗粒之间的互滑摩擦和运动更为强烈。