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利用分离式霍普金逊压杆装置(SHPB)进行单轴动态压缩实验,研究砂岩经历25℃～800℃高温作用冷却后,密度、纵波波速、峰值强度随温度的变化规律;同时从破坏模式、块度分布以及高速摄影特性角度分析了高温后砂岩的动态破碎特性。研究结果表明:随着温度的升高,试样的密度、纵波波速、峰值强度均逐渐减小,200℃后纵波波速降低的幅度增大,400℃～600℃之间峰值强度降低幅度较小,800℃后峰值强度急剧下降;历高温后砂岩的动态破碎特点主要为拉伸破坏,且随着温度的升高,破碎程度越大,岩块分布趋细粒化。通过高速摄影仪拍摄图象,直观地再现了岩石动态破坏过程,发现纵向裂纹沿加载方向随机分布在岩样四周,且初始载荷时岩石破碎形态不具代表性而是随着应力波多次反射才形成最终的破坏形态。
Uniaxial dynamic compression experiments were carried out by using the split Hopkinson pressure bar device (SHPB) to study the variation law of density, longitudinal wave velocity and peak intensity with temperature after the sandstone subjected to the high temperature of 25 ℃ ~ 800 ℃. At the same time, , Block size distribution and high-speed photography characteristics of sandstone dynamic crushing characteristics after high temperature. The results show that with the increase of temperature, the density, longitudinal wave velocity and peak intensity of the sample decrease gradually, and the amplitude of the decrease of the longitudinal wave velocity increases after 200 ℃. The decrease of the peak intensity between 400 ℃ and 600 ℃ is small , The peak intensity sharply decreased after 800 ℃. The dynamic crushing characteristics of sandstone after high temperature were mainly tensile failure, and with the increase of temperature, the greater the degree of crushing and the distribution of rock mass became finer. The images were captured by a high-speed camera and the dynamic failure process of the rock was visually reproduced. It was found that the longitudinal cracks were randomly distributed around the rock specimen along the loading direction. The rock fragments were not representative at initial load but formed with multiple reflections of the stress wave The ultimate form of destruction.