含预制裂隙大理岩破坏过程声发射特征研究

采用含预制裂隙大理岩块试件 ,对压剪应力场中试件破坏过程声发射特征进行研究 ,试验表明预制裂纹对试件的影响是显著的。试验观测到不同试件的不同声发射特征 ,这表明它们的损伤断裂过程的不同机制 ,对于一些以张拉型翼裂萌生、扩展为破坏机理的岩样 ,还表现出明显的二次峰值现象。锯齿型裂纹的情况较为复杂 ,其破坏具有不同于其他试件的特征 ,破坏之前有相当长一段时间 ,声发射也较为活跃 ,且增幅越来越大 ,破坏时出现最高峰值 ,破坏一瞬间的振铃累积数几乎达到全过程的一半 ,这表明含锯齿形裂纹的材料的破坏更具有突然性和不可预测性 ,对岩石材料强度以及岩体稳定性有关键的影响

Acoustic Emission Characters of Pre-cracked Marble under Compression

An experimental study on the characters of acoustic emission (AE) of marble samples with pre existed cracks under compression is carried out. The experiment results show that the pre existed cracks have significant influence on the rock samples. Different acoustic emission characters indicate different failure mechanisms of rock samples with different cracks. For some rock samples, in which the failure is due to the initiation and propagation of tension mode wing cracks and a secondary peak value of AE counts is observed. For the samples with pre existed zigzag cracks, the failure mechanism is more complicated. In a fairly long time before collapse, the acoustic emission is active and the increase of AE counts becomes larger with increase of the load. As the sample collapses, the AE number reaches a peak value and the accumulated AE counts of failure process occupies almost half of the sum for whole loading process. This reveals that the failure of materials with pre existed zigzag cracks is unexpected and unpredictable. The zigzag cracks have key influence on the strength and stability of the rock mass.