Study on the mechanism of dynamic slip-weakening for a rock material interface based on a vibration experiment

Abstract

Slip-friction of faults and joint fractures is of great significance in the study of rock mass structural engineering stability and earthquake generation mechanism. Laboratory friction experiment is a great method to determine the frictional strength of rock interfaces. A large number of low-velocity experiments has been conducted to explain the friction mechanism in the regime of direct shear mode. However, the friction mechanism in the regime of vibration mode has rarely been studied. To study the slip-friction mechanism of rock interface under the vibration mode, a dynamic friction experiment with two blocks on a vibrating platform was performed. The experiments were conducted with hard granite samples at a vibration frequency of 1–10Hz, vibration amplitude 0.5–5mm, and normal stress of 0.5–4.5MPa. The results demonstrate that slip- and frequency-weakening phenomena were noticed and the general quantitative relationship of the three characteristic friction parameters is μ 3 > μ 1 > μ 2. Moreover, the normal stress has a significant effect on the weakening degree of the friction coefficient, and the change in the surface roughness may correlate with the change in the weakening degree.