Study on damage law of layered composite rock under uniaxial compression test after high temperature
In order to study the effect of high temperature in deep environment on the physical properties,deformation and failure mechanism and damage evolution law of layered composite rocks,uniaxial compression tests were carried out on layered composite rock after high temperature of 30,60,90,120,150,180℃,and the failure process of rock was monitored by acoustic emission instrument.Taking the cumulative ringing count as the damage variable,considering the initial damage introduced by high temperature,the elastic modulus of layered composite rock was obtained by composite equivalent method.The whole-process stress-strain constitutive model was derived according to the axial strain of crack and the cumulative ringing count.The results show that after the layered composite rocks undergoes high temperature,the higher the temperature,the stronger the ductility of the rocks in the initial compaction stage of the rock.The peak strength is negatively correlated with the increase of temperature after high temperature.The ringing count in acoustic emission is well corresponded with the initiation,extension,and coherence of cracks in the process of rock damage and failure.With the increase of temperature,the layered composite rock changes from brittle to elastic-plastic,and the failure mode changes from vertical splitting failure to Y-type shear failure.The established whole-process stress-strain constitutive model can well reflect the damage evolution law of layered composite rock.The research findings can provide reference for rock engineering in high temperature environment.
layered composite rockhigh temperatureuniaxial compression testacoustic emis-sionconstitutive model
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