粉砂岩失稳过程的红外高温点聚集异常

Abnormal aggregation of infrared high temperature points in process of siltstone failure

临破裂岩石热图像存在高低温区域空间分异,为定量研究岩石红外温度场的高温区空间分布聚集程度变化特征,进行了粉砂岩单轴压缩下的红外监测实验.先以红外温度场的第95百分位数为高温阈值,识别、提取高温点;又结合点密度样方分析法,以扩散系数定量衡量红外高温点的聚集程度,重点对粉砂岩加载过程中红外高温点聚集程度变化特征进行了研究.结果表明:加载过程中,粉砂岩红外温度场高温点扩散系数的波动性较弱、递增趋势明显,阶段特征表现为快-慢-快的反"S"型变化;其中,在塑性-峰后破坏阶段,红外高温点扩散系数的快速升高特征可作为岩石失稳的异常前兆,该前兆稳定出现,频率可达80%.

The high and low temperature region spatial anomalies of thermal image exist approaching rock failure under loading. To quantitatively determine the variation of aggregation degree of high temperature points, the infrared experiment was carried out under the condition of uniaxial compression. The high temperature points are extracted according to the ninety-fifth percentile of the infrared temperature field through quadrat analysis method. Using the diffusion coefficient to quantitatively measure the aggregation degree of high temperature points, the variation characteristics of the spatial distribution of high temperature points in the loading process of siltstone was studied. The results show that： in the process of loading, the diffusion coefficient fluctuation is weak with apparently increasing trend. The stage characteristic is fast-slow-fast change like a reversed ＂S＂; in the stage of plastic deformation and post peak, rapid rise characteristics of diffusion coefficient of infrared high temperature points can be used as a precursory anomalies of rock steady loss, whose occurrence probability can be up to 80 %.