Experimental Study on Tensile Strength Evolution Characteristics of Granite After Interval Temperature Cycle
In order to reveal the evolution law of physical properties and tensile strength of granite after cyclic heat treatment at 300-150 ℃,the natural water absorption rate and longitudinal wave velocity of granite after different heat treatment cycles were measured,and the Brazilian splitting tests were carried out.The acoustic emission technique was used to monitor the acoustic characteristics of the failure process.The results are concluded as follows.Firstly,after 300-150 ℃ cyclic heat treatment,the natural water absorption rate of granite increases,the variation is 0.25％-0.35％,the longitudinal wave velocity decreases,and the attenuation is 1 132.3-1 199.6 m/s.Secondly,the tensile strength of granite decreases exponentially with the increase of heat treatment times.The tensile strength of granite treated at room temperature to 300 ℃ to room temperature is the lowest,which decreases to 13.21 MPa,while the tensile strength of granite treated at 300-150 ℃ cyclic heat treatment is higher than that of granite treated at room temperature to 300 ℃ to room temperature.Thirdly,compared with the room temperature condition,the duration from loading to failure of granite after cyclic heat treatment shows a decreasing trend,and the cumulative energy mutation of acoustic emission and the peak ringing number appear before the peak load.Fourthly,after the cyclic heat treatment of granite at 300-150 ℃,the acoustic emission cumulative energy and the wave velocity damage variables monitored at the time of failure are opposite to the trend of the number of cycles.The research results can provide a reference for the physical and mechanical evolution behavior of granite under a certain temperature interval cycle.
Temperature cycleBrazilian splittingAcoustic emissionTensile strengthArtificial thermal reservoir
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