饱水、干燥砂岩损伤破坏声、热异常信号及敏感性耦合分析

Acoustic and thermal anomaly signals and sensitivity coupling analysis of damage to water-saturated and dry sandstones

为进一步研究饱水、干燥砂岩损伤破坏异常前兆时序信号以及声、热信号的动态敏感性变化,开展不同含水状态砂岩单轴压缩试验,并实时监测砂岩内部声发射信号和表面热红外信号。研究表明:饱水砂岩热红外异常信号率先出现,声发射异常信号滞后出现;而干燥砂岩则相反;饱水砂岩声、热两类异常信号首次出现的时间差小于干燥砂岩,该时间差对于判断砂岩内外损伤加剧程度有重要参考意义,水减少了该时间差,增加了对饱水砂岩损伤破坏的监测难度;饱水砂岩声、热信号动态敏感性指标强弱顺序为:声-热联合信号>热红外信号>声发射信号;干燥砂岩声、热信号动态敏感性指标强弱顺序为:声-热联合信号>声发射信号>热红外信号。声-热联合信号敏感性明显高于声、热信号,因此在实际工程中分析失稳前兆时,对声、热信号耦合分析是十分有必要的。

In order to further study the precursor temporal signals of damage in water-saturated and dry sandstones,as well as the dynamic sensitivity changes of acoustic and thermal signals,uniaxial compression tests were conducted on sandstones with different water content states,with real-time monitoring of internal acoustic emission(AE)signals and surface thermal infrared(TIR)signals.Research has shown that during the damage process of water-saturated and dry sandstones,TIR anomalies appear first,followed by AE anomalies.The time lag between the first appearances of TIR and AE anomalies in water-saturated sandstone is shorter than that in dry sandstone,indicating the detrimental effect of water.This time lag is of great significance for determining the degree of internal and external damage and the precursor of instability failure in rock samples.The order of sensitivity indicators for acoustic and thermal signals in water-saturated sandstone is as follows:combined acoustic-thermal signal>TIR signal>AE signal;for dry sandstone,it is:combined acoustic-thermal signal>AE signal>TIR signal.The sensitivity of the combined acoustic-thermal signal is significantly higher than that of individual acoustic or thermal signals.Therefore,in practical engineering,it is necessary to analyze the coupling of acoustic and thermal signals when analyzing the precursors of instability.