Experimental Study on the Charge Signal Time-Frequency Characteristics during Fracture Process of Precracked Syenogranite under Uniaxial Compression

During the process of rock deformation and failure, a significantly large number of charge signals are generated as a result of fracture appearance and crack expansion. The generation of charge signal is the comprehensive embodiment of the coal-failure behavior. The study of charge signal in the process of fractured-rock deformation and failure is of great significance to the prediction of rock dynamic disasters such as tunnel-engineering stability, slope instability and earthquake. In this work, a surveillance system utilizing charge induction is employed to extract precursory information related to the instability and failure of precracked syenogranite. The results reveal a significant influence of fractures on the strength of syenogranite specimens and the number of charge-induction signal events. The position of the charge signal generated is related to the crack dip angle. Furthermore, with the increase of the crack inclination, the number of events and the amplitude and power value of the charge-induced signal increase and reach the maximum in the instability-failure phase. The syenogranite specimen has a relatively large value, medium correlation, or even high correlation charge-induction signal in the phase of rack propagation, which can make an early warning of the deformation and failure risk of syenogranite; with the increase of the fracture degree, the charge-induction signal with large values and high correlations gradually increases.