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利用MTS652.02高温炉与φ50 mm分离式霍普金森压杆(SHPB)试验系统,对800℃加热后的砂岩试样进行单轴冲击压缩试验,分析17.904~62.600 s-1应变率范围内砂岩动力特性的变化规律。结果表明:800℃后砂岩动态应力-应变曲线大致经历压密、近似线弹性变形、微裂纹演化、裂纹非稳定扩展、应变软化以及卸载6个阶段;随着应变率提高,砂岩动态弹性模量、峰值应力随应变率的提高基本呈对数形式逐渐增加,峰值应变近似呈对数形式逐渐降低;较低应变率下,砂岩破坏为典型的张拉破坏,随着应变率的升高,剪切破裂面所占比例逐渐升高,砂岩破坏型式具有从张拉破坏向剪切破坏的变化趋势;800℃热处理后,砂岩破坏程度随应变率的提高逐渐提高,并且高应变率下破坏程度的应变率敏感性更加显著。
Sandstone specimens heated at 800 ℃ were subjected to uniaxial impact compression tests using the MTS652.02 high temperature furnace and the φ50 mm split Hopkinson pressure bar (SHPB) test system. The sandstone samples in the range of 17.904 to 62.600 s-1 strain rate Dynamic characteristics of the law of change. The results show that the dynamic stress-strain curve of sandstone at 800 ℃ generally experiences six stages of compaction, approximate linear elastic deformation, microcrack evolution, crack instability expansion, strain softening and unloading. With the increase of strain rate, the dynamic elastic- , The peak stress gradually increases with the increase of strain rate in logarithmic form and the peak strain decreases logarithmically. Under lower strain rate, the failure of sandstone is a typical tensile failure. With the increase of strain rate, The proportion of fractured surface gradually increased, and the sandstone failure mode changed from tensile failure to shear failure. After 800 ℃ heat treatment, the failure degree of sandstone gradually increased with the increase of strain rate, and the damage degree under high strain rate Strain rate sensitivity is more pronounced.