单轴压缩下花岗岩声发射、红外特征及损伤演化试验研究

Acoustic emission, infrared characteristics and damage evolution ofgranite under uniaxial compression

采用声发射、热红外技术联合监测花岗岩单轴压缩过程,分析岩石破裂过程声发射、红外辐射变化规律。从内部损伤和表面损伤两个角度,分别建立了基于声发射和红外辐射的岩石损伤变量解析表达式,并根据二者在不同阶段的互补性,建立了分段曲线损伤模型,分析单轴压缩下岩石的损伤演化特征。研究结果表明,(1)岩石损伤演化过程分为初始损伤阶段、损伤稳定发展阶段和损伤加速发展阶段3个阶段,初始损伤阶段内部损伤和表面损伤都没有发展,损伤稳定发展阶段,内部微损伤不断积聚,表面损伤仍没有发展,损伤加速发展阶段内部损伤和表面损伤均快速增大。相比内部损伤,表面损伤异常增大时间较早;(2)对比分段曲线损伤模型计算出的应力-应变曲线与试验应力-应变曲线发现两者的趋势大致相同,定义的损伤变量较为合理,能够较好地反映岩石内部裂纹缺陷产生、发展直至破坏的渐进演化过程。

The uniaxial compression process of granite is monitored by acoustic emission and thermal infrared technology,and the variations of acoustic emission and infrared radiation during rock fracture are analyzed.On this basis,the analytical expressions of rock damage variables are derived from the perspectives of internal damage and surface damage.According to the complementarity of these two at different stages,a piecewise curve damage model based on sound-heat is established to study the damage evolution characteristics of rock under uniaxial compression.The results show that:(1)The damage evolution process of rock can be divided into three stages:initial damage stage,stable damage stage and accelerated damage stage.In the initial damage stage,neither internal damage nor surface damage develops.In the stable damage stage,the micro-damage in rock accumulates continuously,but there is no development on the surface damage.In the accelerated damage stage,both the internal damage and the surface damage increase rapidly.Compared with the increase in internal damage,the abnormal increase in surface damage occurs earlier.(2)By comparing the stress-strain curves calculated from the comprehensive damage variables with the experimental curves,it is found that the trend of the two curves is approximately the same.The comprehensive damage variables defined are reasonable and can better reflect the progressive evolution of crack defects in rock from generation,development to failure.