Abstract:The studies on remote sensing rock mechanics(RSRM) in recent years show that rock has regular features of infrared radiation(IR) when the rock is loaded,and the anomalous IR phenomena appear before rock fracture. In order to understand the IR feature of loaded rock and its physical mechanism,the IR features of rock under uniaxial compression are compared with those of polymethyl mechacrylate(PMMA) under similar conditions. The results show that:(1) during the whole loading process,the radiation intensity of PMMA increases symmetrically and no local anomaly appears in the thermal image,but the anomalous radiation appears frequently in the thermal image of rock before fracture,and it appears in strips and the location of strips corresponds to those of rock fractures;and (2) different stress stages show different IR features,but the IR patterns of two materials are different. The average IR radiation temperature(AIRT) of PMMA rises in the form of sectional line with the variation of stress state. However,AIRT variation curve of rock with time presents diverse forms,and the anomalous AIRT precursors appear before rock fracture. The mechanism of thermomechanical coupling is discussed and the result shows that the thermomechanical coupling effects of rock include thermoelastic effect,endothermic effect caused by gas escaping,and friction heat effect due to generation of a mass of cracks. Comparatively,PMMA has thermoelastic effect,thermoplastic and thermoviscous effects. The difference of thermomechanical coupling effect is the cause to result in IR feature difference between rock and PMMA.