循环冲击下高温层理砂岩的动力学特性及损伤模型OA

To investigate the dynamic characteristics and dynamic damage constitutive model of high-temperature bedding sandstone under cyclic impact,the physical properties of bedding sandstone after exposure to 300−1 100 ℃ were first exa-mined,and the influence of temperature on the color,mineral composition,mass and wave velocity of the specimens was recorded. Second,the dynamic characteristics of high-temperature bedding sandstone under cyclic impact were studied with a split Hopkinson pressure bar (SHPB) apparatus,and the dynamic responses of bedding sandstone at different strain rates and impact numbers were analyzed. Finally,on the basis of the visco-elastic damage element model for bedding rock,a dynamic constitutive model that accounts for high-temperature-impact-load coupling damage was established and verified against experimental data. The results show that the crystallization temperature of the dominant mineral quartz lies between 500 ℃ and 700 ℃;the higher the temperature,the darker the apparent color of the rock and the lower its mass. With increasing tem-perature,the wave velocity and peak stress first decrease and then increase. Temperature inflicts greater damage on 0° and 45° bedding sandstone,and the damage is most pronounced at 900 ℃. Under an impact voltage of 1 300 V,the peak stress of bed-ding sandstone increases and then decreases with increasing impact number. Impact loading renders 0° bedding sandstone more susceptible to failure after high-temperature exposure,whereas 45° and 60° bedding sandstone exhibit strong impact resistance.The difference between the predicted and experimental curves is small,indicating that the model satisfactorily describes the cyclic-impact mechanical behavior of high-temperature bedding sandstone. The findings provide a valuable theoretical reference for the prevention and control of rock dynamic disasters in complex deep geothermal engineering environments.