Abstract: In this paper, the variation rules of electric potential signals during fracture process of tunnel sandstone and the precursor characteristics before rupture were studied. The results show that the electric potential signals will be generated in the fracture process of sandstone, and there is close corresponding relation between the electric potential signals and deformation and fracture of the samples. Meanwhile, the potential signals are more sensitive to the deformation and failure, and the propagation of cracks at the initial stage of loading, while the acoustic emission is fewness, and the potential amplitudes slightly reduce at the later stage of loading while the acoustic emissions increase abundantly. Within 70%~97% of the peak strain in the process of accelerating deformation, there will exit strong pulse potential signals, thus, the sharply increase of potential before strain peak can be used as the precursor characteristics of sandstone rupture. Through the study of variation rules of electric potential during rock failure, it can deepen our understanding in the rock micro-fracture process which may provide basic research results for monitoring tunnel rock mass stability and construction safety by using the electric potential technology.

Key words: sandstone, rupture；electric potential；precursor characteristics；acoustic emission