砂岩单三轴压缩过程中声发射特征的试验研究

Uniaxial, triaxial compression tests and triaxial unloading confining-pressure tests for roof sandstones form Caoyao Coal Mine, Yima Coal Group, were carried out with servo-controlled test machine RMT-150B, and acoustic emission (AE) detections were at the same time. Test results indicate that there were different AE events in various conventional compression tests. AE events were different during uniaxial compression tests, but totally high in energy and accumulation number. During triaxial compression tests, AE events were less before specimens yielding, and gradually increase after specimens yield; AE events with much stronger energy were still created in the process of friction slippage of specimens while their stress after peak value sharply decreased. AE events for specimens were much more intensive, their accumulative counts and energy were obviously higher in uniaxial compression tests. The higher the confining pressure for specimens was, the weaker AE characteristic parameters were. AE events were comparatively less before unloading confining-pressure, gradually more active in the process of unloading confining-pressure, which the count and energy of AE events greatly increased. When the stress after peak value on specimens sharply decreased to the lowest, then AE events would reduce rapidly, but the total counts and energy of AE events were basically the same. Specimens broke unstable during unloading confining-pressure tests, but their unstable fractures were more outburst.