Experimental Research on Ultrasonic P-Wave Velocity Variation of Fractured Rock Mass under Different Stress Paths

Abstract

Based on the similarity theory, rock-like material had been adopted to simulate deep buried marble of Jinping-II Hydropower Station’s diversion tunnel. Specimens which contains different spatial distributions of fractures had been used in the triaxial compression, tension and compression test, and the stress-velocity of ultrasonic P-wave curves were acquired. The result shows that in the triaxial compression test, the velocity of P-wave increased with the axial compression increasing when confining pressure was constant, the increasing rate was firstly swift and then slowed down, the velocity of P-wave increased with the confining pressure increasing when axial compression was constant. In the triaxial tension and compression test, the velocity of P-wave decreased with the confining pressure increasing when axial tensile stress was constant. Under the same stress state, the larger the angle between the propagation direction of ultrasonic P-wave and the fractures, the smaller the ultrasonic P-wave velocity.