Abstract: Yinjiang granite specimens 50?50? 100mm³ in size are tested under true triaxial compressions of σ₃=30 MPa,σ₂=60MPa and increasing σ₁ until the specimens fracture. We determined the P-wave Q-value of acoustic emission in σ₃ and σ₂ directions in the fracture process of specimens from the wave propagation and the spectral amplitude ratio. The obtained result shows that P-wave Q-vaiue and spectral amplitude of acoustic emission show their significant characteristic variation,which are anisotropic. We found an abnormal phenomenon:after σ₁>0.95σ_IP,for the amplitudes of waves emitted from same source,those which are received by near probe are smaller,and those which are received by far probe are larger.

Key words: P-wave Q-value, Acoustic emission, Spectral amplitude, Fracture plane

摘要： 50×50×100mm³盈江花岗岩样品在σ₃=30MPa、σ₂=60MPa时增加σ₁直至破裂,用波传播和谱振幅比法测定破裂孕育过程中σ₃方向和σ₂方向声发射P波Q值。结果表明:1.在σ₁<0.07σ_1P(最大破裂压强)时,σ₃、σ₂方向都保持高值,在0.2σ_1P≤σ₁≤0.55_1P期间,两个方向的Q值呈现出比较平稳的状态,其平均值Q₃大约10至20,σ₂方向Q₂大约20至30。在σ₁>0.55σ_1P后,σ₃方向Q₃值起伏增长较大,而σ₂方向Q₂值仅在σ₁>0.7σ_1P后,才起伏增长,幅度不如σ₃方向大。2.随压力的增加,在σ₃、σ₂两方向,低频成分明显加大。3.当σ₁>0.95_1P后,出现一种记录畸变现象,对同一源点声发射,从沿同一方向两道记录上看出,早到波形振幅小,而晚到波形其振幅反而大。

关键词: P波Q值, 声发射, 谱振幅, 主破裂面