Experimental study of open fracture's multifarious effects on ultrasonic wave propagation in rock masses

Abstract

A comprehensive understanding of the fracture's effects on wave propagation is a necessary prerequisite for estimating the dynamic behavior of fractured rock masses. This study presents a series of ultrasonic experiments on the multifarious effects of open fractures on the propagation characteristics of waves, considering various geometric parameters of fractures. The results indicate that fractures disrupt the waveform and attenuates the wave amplitude and velocity. With the increase of fracture width, the amplitude of transmitted wave and the dominant frequency of transmitted wave decrease, while the transmit time of wave in the sample increases. An increasing fracture dip angle generally leads to the increase of wave amplitude and dominant frequency, while reduces the transmit time of wave. As the fracture spacing increases in the testing range, the wave amplitude increases, while the wave frequency exhibits an opposite tendency. Comparing with the experimental results in the cases of single and multiple fractures, it is confirmed that the attenuation effect and the low-pass effect of fractures on wave propagation are enhanced quickly with the increase of fracture number.