A Study on the Characteristics of Amplitude Attenuation Related to the Radiation Pattern of Longitudinal Wave in Acoustic Emission

Three kinds of rock specimen containing the straight notch were selected to be used in this research. Source mechanism of micro-crack by radiation pattern based on dislocation theory was estimated by the first motion of longitudinal wave, spatial distribution between the location of transducers for monitoring acoustic emission, and source coordinates determined by the application of the least square method. Result of analysis showed that the orientation of crack surfaces due to shear dislocation and tensile dislocation squares considerably coincided with crack direction visually observed. And result of analyzing attenuation property using the first motion of longitudinal wave out of surface pulse input and cracks due to tension and shear force based on dislocation theory revealed that attenuation constant has the greatest value in granite, less in sandstone and the smallest in marble.