热处理后花岗岩动态拉伸特性及能量耗散研究

Study on dynamic tensile properties and energy dissipation of granite after thermal treatment

为研究热处理后花岗岩动态拉伸特性及能量耗散规律,利用分离式霍普金森压杆(SHPB)装置,分别对常温(25℃)和经历200~800℃热处理后的花岗岩试样进行3组冲击速度下的动态劈裂拉伸试验,探讨温度、冲击速度与花岗岩动态拉伸强度及能量之间的关系。结果表明:在冲击速度一定时,随着温度的增加,试样拉伸强度整体呈下降趋势;在温度一定时,试样的动态拉伸强度随着应变率的增加逐渐增大;试样的耗散能在劈裂荷载作用下经历4个阶段:压密阶段、弹性阶段、屈服损伤阶段、完全破坏阶段,且温度越高,用于试样破坏的能量越少,耗散能、能耗密度下降幅度越大;试样的破坏形态对温度的敏感程度高,即随着温度的升高,试样破碎程度加剧,碎块对称性消失,楔体效应更明显,塑性增强。

To study the dynamic tensile properties and energy dissipation of granite after thermal treatment,the split Hopkinson pressure bar(SHPB)device was used to conduct three groups of dynamic splitting tensile tests on granite samples after heat treatment at room temperature(25℃)and 200-800℃,respectively.The relationships between temperature,impact speed and dynamic tensile strength and energy of granite were discussed.The results show that when the impact speed is constant,the tensile strength of the sample decreases as the temperature increases.At a certain temperature,the dynamic tensile strength of the specimen increases gradually with strain rate.The dissipation energy of the specimen under the splitting load can be categorized into four stages:compaction stage,elastic stage,yield damage stage,and complete failure stage.It has been observed that as the temperature increases,less energy is required to cause specimen failure.Furthermore,the range of dissipated energy reduction and energy consumption density decrease gradually with increasing temperature.The failure characteristics of the sample exhibit a high sensitivity to temperature variations.Specifically,as the temperature increases,the degree of sample fragmentation intensifies,the symmetry of the resulting fragments diminishes,the wedge effect becomes more pronounced,and the overall plasticity of the sample is enhanced.