受不同加载偏转角影响的含裂纹砂岩劈裂声发射试验研究

Acoustic emission characteristics of cracked sandstones affected by different rotating angles of loading under splitting tests

目前,岩石声发射方向性存在与否尚无定论,岩石中裂纹的存在对岩石声发射方向性是否存在影响也无深入的研究。针对完整的和含有一条预制裂纹的砂岩圆盘试件,分别偏转5°,10°,15°,35°,60°角进行岩石声发射方向性验证劈裂试验,对比分析了不同加载偏转角度下完整砂岩和含预制裂纹砂岩的声发射特征。研究表明：（1）偏转角度的不同对砂岩声发射Kaiser效应确有影响,随着偏转角度的增大,砂岩声发射Kaiser效应逐渐模糊直至消失,证明在此试验条件下砂岩的声发射Kaiser效应方向性随着偏转角度的增大而愈加明显。（2）含裂纹砂岩的Kaiser效应方向性比完整砂岩的Kaiser效应方向性更明显,具体表现为含裂纹砂岩的声发射Kaiser效应比完整砂岩在偏转过程中消失得更快。研究成果可为利用Kaiser效应测量地应力的可行性和准确性提供试验论证。

At present, whether the acoustic emission possesses directionality or not is still inconclusive. Besides, the influences of cracks on the acoustic emission directionality are not intensively studied. The cleavage experiments are respectively carried out at rotating angles of 5°, 10°, 15°, 35° and 60° by using the intact disc sandstone and disc sandstone containing a prefabricated crack. The acoustic emission characteristics of the complete sandstone and the prefabricated cracked sandstone under different loading rotating angles are compared and analyzed. The results show：（1） The difference of rotating angles has an effect on the Kaiser effect of acoustic emission of sandstone. With the increase of rotating angles, the Kaiser effect of acoustic emission of sandstone gradually blurs until it disappears, verifying that the directionality of acoustic emission of rock becomes more obvious with the increase of rotating angle in this experimental condition.（2） The Kaiser effect directionality of cracked sandstone is more obvious than that of intact sandstone, for the Kaiser effect disappears faster in cracked sandstone than in the intact sandstone in the process of rotating. The results of the study can provide experimental proofs for the feasibility and accuracy of using the Kaiser effect to measure geostress.