Abstract: Multi-physical field information fusion is a research hotspot of rock mass instability early warning.The charac teristics of acoustic emission and infrared temperature change in different stages of rock failure process were studied by using infrared temperature mutation ratio (ITMR) and acoustic emission mutation rate (AEMR) as quantitative indexes.The results show that the tangent modulus in loading process of the specimen presents the stage characteristics of “rapid rise-steady rise rapid decline”.The crack initiation strength determined by the maximum value of the steady rise and fall stage is 83.39 MPa, which is about 53% of the peak strength.With the increase of strain,the change rate of tangent modulus shows the stage char acteristics of “rapid decline-steady decline-rapid decline”.There is an obvious inflection point between steady decline and rap id decline.According to the inflection point,the damage strength is 139.67 MPa,which is about 89% of the peak strength. Taking the crack initiation strength and damage strength as the boundary,the deformation process of the specimen can be divid ed into compaction-elastic stage Ⅰ,crack initiation and stable propagation stage Ⅱ,and crack unstable propagation failure stage Ⅲ.There is a clear complementary relationship between AEMR and ITMR abnormalities.In stage Ⅰ,the changes of AE MR and ITMR are relatively stable,showing stable fluctuations in a small range.In stage Ⅱ,AEMR shows dramatic large-scale abnormal jumps frequently,which can be used as a precursor to rock failure,while ITMR changes smoothly.In stage Ⅲ,AEMR first has a large jump anomaly,and then reaches a quiet period,while ITMR large jump anomaly is more obvious,which can be used as a late precursor of rock instability.The research results are of great significance for the joint early warning of infrared andacousticemissiontopromotetheinstabilityof geotechnical engineering.

Key words: rockinstability,infraredtemperaturemutationratio,acousticemissionmutationrate,catastrophicwarning