岩石破坏声发射强度分形特征研究

STUDY ON STRENGTH FRACTAL FEATURES OF ACOUSTIC EMISSION IN PROCESS OF ROCK FAILURE

通过对岩石单轴受压破坏全过程的声发射实验,建立了岩石破坏声发射强度分维模型,研究了岩石破坏全过程各个应力水平声发射分形特征以及分形维值随实验时间的变化规律。研究结果表明:加载初期岩石试件声发射强度分形维值变化不稳定,分形维值的大小变化有反复,但从分形维值总的变化趋势来看,这一阶段的分形维值还是处于较大水平;加载中后期声发射强度分形维值出现较强的规律性,其值逐渐由大变小,试件破坏前的分形维值最小。由于实际应用中最小分形维值点(临界值点)难以确定,故提出将岩石破坏前声发射强度分形维值的持续降维作为岩石破坏的前兆特征,从而对利用声发射参数进行岩体稳定性现场监测预报提供理论依据、方法和手段。

Through the acoustic emission（AE） experiments in the process of rock failure, the strength fractal model of acoustic emission in the process of rock failure is established. The AE fractal features of all stress levels in the whole rock failure and the changing rules of fractal value, which varies from time to time, are studied. The results show that, in the initial stage of loading, the AE fractal value of rock samples is unsteady. But from the viewpoint of the general changing trend, the fractal value in this period still remains greater. In the middle and later stage, the fractal value has obvious regularity, changing from great to small. The fractal value reaches to the minimum at the critical point of sample failure. Since it is difficult to confirm the minimum fractal value （critical value） in practical application, it is found that the continually declining fractal value is the premonitory feature of rock failure. Consequently, it provides theoretical basis and means for in-situ rock mass monitoring and forecast by acoustic emission parameter.