摘要:
为研究循环冲击下高温层理砂岩的动力学特性及动态损伤本构模型,首先对高温(300℃~1100℃)作用后层理砂岩的物理特性进行测试;其次利用霍普金森压杆(split Hopkinson pressure bar,SHPB)装置开展了循环冲击下高温层理砂岩动力学特性研究;最后,基于层理岩石粘弹性损伤元件模型,构建了考虑高温-冲击荷载耦合损伤的层理岩石动态本构模型,并通过实验数据对模型进行了验证。结果表明:砂岩主要矿物晶体石英的变晶温度处于500℃~700℃之间。温度越高,砂岩表观颜色越深,质量越小,波速和峰值应力先减小后增大。温度对0°、45°层理砂岩造成的损伤更大,900℃时损伤最为显著。在1300V冲击电压下,层理砂岩的峰值应力随冲击次数的增加呈现先升后降的趋势。冲击荷载使高温后的0°层理砂岩更容易破坏,而45°和60°层理砂岩表现出较强的抗冲击能力。模型预测曲线与试验曲线相差较小,表明该模型在描述高温层理砂岩循环冲击力学特性方面具有良好的适用性。研究结果可为深部地热工程围岩动力灾害防治提供理论参考。
Abstract:
To study the dynamic characteristics and dynamic damage constitutive model of high temperature bedding sandstone under cyclic impact, the physical properties of bedding sandstone after high-temperature (300 °C ~ 1100 °C) were studied firstly, and the influence of temperature on the color, mineral composition, quality and wave velocity of bedding sandstone specimens was recorded. Secondly, the dynamic characteristics of high-temperature layered sandstone under cyclic impact were studied by using the split Hopkinson pressure bar (SHPB) device, and the dynamic characteristics of bedding sandstone with different strain rates and impact times were analyzed. Finally, based on the viscoelastic damage element model of bedding rock, a dynamic constitutive model of bedding rock considering high-temperature impact load coupling damage was constructed, and the model were verified by experimental data. The results indicate that, crystallization temperature of the main mineral crystal quartz is between 500 °C and 700 °C. The higher the temperature, the darker the apparent color of the rock, the smaller the mass. As the temperature increases, the wave velocity and the peak stress first decreases and then increases. The temperature causes more damage to the 0° and 45° bedding sandstone, and the damage is most significant at 900 ℃. Under the impact voltage of 1300 V, the peak stress of bedding sandstone increases first and then decreases with the increase of impact times. Impact load makes 0° bedding sandstone more prone to failure after high temperature, while the 45° and 60° bedding sandstone show strong impact resistance. The difference between the model prediction curve and the test curve is small, indicating that the model has good applicability in describing the cyclic impact mechanical properties of high temperature bedding sandstone. The research results can provide a valuable theoretical reference for the prevention and control of rock dynamic disasters in complex deep geothermal engineering environments.