Analysis of Acoustic Emission and Fractal Characteristics of Granite Under Step Loading
An acoustic emission(AE)test of granite under uniaxial step loading was carried out,and the evolution characteristics of AE frequency,event incidence and fractal dimension of the sample at each load-holding stage before occurrence of instability and fracture were analyzed.The results show that the high-frequency signal first decreases and then increases with the increase of stress in the process of step loading;and macro-instability occurs in the sample at the last stage of step loading,at which the internal micro-cracks in the sample undergo from stable propagation to unstable propagation.The incidence of acoustic emission events decreases gradually as time is prolonged.At the last stage of step loading,the incidence of acoustic emission events decreases first and then increases,unstable fracture in the rock increases and micro-cracks gradually merge and coalesce to form macro-cracks,resulting in overall instability and fracture of the sample;with the increase of stress,the fractal dimension of acoustic emission decreases after an initial increase,and the rock fracture develops gradually in an order way from a disorder way.
万方数据
维普
