关键词: 砂岩圆盘试样;垫块包围度数;b值;声发射;Kaiser效应;

Abstract: To study the influence of contact area between the steel spacers and specimen on the acoustic emission (AE) characteristics of rock samples, a series of uniaxial loading and unloading tests were performed to analyze the AE characteristics of the sandstone disc specimen with contact arc angle of 10°, 30°, and 60°. The results showed that with the increase of the contact angle, Kaiser effect was not influenced, however accumulative AE count, accumulative AE energy count, peak strength were clearly improved, while the specimens’ failure mode was transformed from a single splitting failure at the load diameter vicinity to a complex failure of contact end breaking firstly. During the cyclic loading and unloading test, the evolution law of the AE b-value of the sandstone under different contact areas was generally consistent. The degree of the internal damage of the specimen at different loading stages was different, and the b-value showed a certain evolution law. The results can provide experimental proof for the measurement of the ground stress by using the Kaiser effect as well as analysis of rock failure process.

Key words: sandstone disc; contact arc angle; b-value; acoustic emission; Kaiser effect