This research investigates the effects of high temperatures, multiaxial stress constraints, and impact loads on the failure behavior and strength deterioration of high-performance concrete. Combined with scanning electron microscopy and ultrasonic testing, the microscopic deterioration characteristics of thermally damaged concrete were revealed. Dynamic compression tests were performed on concrete, after exposed to elevated temperatures (from 25 °C to 750 °C), using a true triaxial Hopkinson pressure bar test system. The study analyzes the effect of temperature and strain rate on dynamic failure behaviors of concrete under biaxial stress constraints. The study establishes models for predicting the evolution of dynamic strength deterioration and strain rate. Additionally, the research discusses the mechanisms of influence of stress constraint states on the dynamic increasing factor (DIF) and failure modes of concrete. Results indicate that concrete's strength under biaxial stress constraints increases with the load rate and is hardened or weakened by changes in temperatures (taking 300 °C as a demarcation point). The strain rate effect of concrete becomes more significant with increasing temperature. Stress constraint states significantly affect the dynamic strength of concrete, and the DIF of concrete grows quasi-linearly with the logarithm of strain rate at different temperatures. Under biaxial stress constraints, concrete is dominated by oblique shear failure, and damage is less severe with the increase in the intermediate principal stress σ₂. Macro-fractures are unlikely to appear under true triaxial stress constraints.

本研究调查了高温、多轴应力约束和冲击载荷对高性能混凝土的破坏行为和强度退化的影响。结合扫描电镜和超声检测，揭示了热损伤混凝土的微观劣化特征。在暴露于高温（从 25 °C 到 750 °C）后，使用真正的三轴霍普金森对混凝土进行动态压缩测试压力棒测试系统。研究分析了温度和应变率对双轴应力约束下混凝土动态破坏行为的影响。该研究建立了预测动态强度退化和应变率演变的模型。此外，该研究还讨论了应力约束状态对混凝土动态增加因子（DIF）和破坏模式的影响机制。结果表明，混凝土在双轴应力约束下的强度随着荷载率的增加而增加，并随着温度的变化（以300℃为分界点）而硬化或减弱。这随着温度的升高，混凝土的应变率效应变得更加显着。应力约束状态显着影响混凝土的动态强度，混凝土的DIF在不同温度下与应变率的对数呈准线性增长。在双轴应力约束下，混凝土以斜剪破坏为主，随着中间主应力σ ₂的增大，破坏程度逐渐减轻。在真正的三轴应力约束下不太可能出现宏观裂缝。