Using the Fiber Bragg Grating (FBG) monitoring technology, the signal characteristics of FBG anchor were studied and analyzed in this paper in order to diagnosis the stability of tunnel roof. To simulate the actual situation, a model experiment was carried out. Then according to the analysis of the experiment results, combining with the cusp catastrophe theory, the instability criterions of surrounding rock were established. The results showed that in the process of roof failure, the FBG signals could be divided in three stages of increase, steady and destructive mutation. During the process, variation of center wavelength was corresponding to the change of mine pressure, and transient vibration signal was corresponding to the blasting vibration. Meanwhile, high pressure would increase the response of signal, and shortened the three stages of signal change cycles. The mutation analyses showed that the mutation indicators could be divided into two types, and the surrounding pressure is the most significant effect of adverse factors.
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