岩石脆性临界破坏的波速特征分析

根据岩石加载破坏过程中应力-应变和波速-应变曲线所反映的的波速变化特征,研究了岩石声波传播速度与其加载变形过程的相关性。研究表明:岩石破裂前波速及特征参数随着变形破坏阶段变化会有显著改变,特别是应力水平到达70%⁸0%之后,当加载破坏过程中岩石的裂隙大量增加后波速参数出现突变。这是由于在膨胀点附近岩石中微裂隙迅速丛集式增长,改变了岩石内部的微观结构,导致岩石波速降低。伴随着波速降低,波速走时急剧增大,离散度增大;S波和P波的振幅减小,但其振幅比急剧增大;S波、P的波Q值也会出现突变。通过对岩石加载过程中的波速变化与应力-应变曲线之间的关联性分析,利用波速信息变化可以实现对岩石脆性破裂前兆的识别。

Analysis of wave velocity characteristics of critical rock brittle failure

This paper studies the relationship between wave velocity and rock brittle failure during the whole process of compression. The complete testing data for the stress-strain curve and the associated wave velocity-stress curve are obtained. The variation caused by internal cracking of the rock causes the corresponding variation of rock wave velocity, especially when the stress level reaches to 70%-80%. Based on the experimental results, it is shown that the stress at the critical point on the stress-strain curve is corresponded to that at the rapid deduced point on the wave velocity-stress curve, where the microcracks are rapidly growing. With the reducing of wave velocity, the travel times and discrete degree of S-wave and P-wave are sharply increasing. The amplitudes of S-wave and P-wave are reducing. However, the amplitude ratio between S-wave and P-wave is increasing. The Q values of S-wave and P-wave have a mutation phenomenon nearby the yield point of stress-strain curve. Considering the relation between wave velocity variation and stress-strain curve, this study shows that wave velocity and its characteristic parameters could be used as the sensitive parameter in the failure process. From this research, we can use the comprehensive information source to indentify the critical point of rock brittle fracture.