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.

Experimental Relationship Between Compressional Wave Attenuation and Surface Strains in Brittle Rock

“…For LSP‐1 and LSP‐3, the magnitude of ε NE AT is nonuniform for the three UIA regions, where the greatest reduction in the transmitted signal amplitude corresponds to the highest strain values (UIA‐3 for LSP‐1 and UIA‐1 and UIA‐2 for LSP‐3 in Figure b). These observations further corroborate the findings of Kurtuluş et al (), Modiriasari et al (, ), and Yang et al () that the presence of cracks caused by locally tensile strain concentrations is the primary cause of attenuation in the ultrasonic wave amplitude in intact rock. Furthermore, these results suggest that the selected strain metrics provide a practically useful representation of microcrack damage in rock for the purposes of understanding ultrasonic wave attenuation.…”

“…Cai and Zhao (2000) also noted that high-frequency waves (ultrasonic waves) propagating through a fractured material are attenuated (and slowed), with each of the fractures contributing individually to wave attenuation like a single discrete feature. Similarly, Huang et al (2014) and Yang et al (2018) found that fractures lead to the loss in transmission (reduction in amplitude) of the high-frequency ultrasonic waves. Based on its definition, any increase in the magnitude of the ε NE AT is analogous to the formation, accumulation, and growth of extensile microcracks in the rock specimens.…”

“…Wave transmission across macroscopic damage features (fractures) in rocks has been extensively studied. Examples of contributions include Pyrak‐Nolte et al (, ), Zhao et al (), Kurtuluş et al (), Huang et al (), and Yang et al (). These studies showed that waves propagating parallel to the normal of the fractures are attenuated, as the fractures act as a low‐pass filter with significant reflection and refraction taking place at the fracture surface.…”

“…The prismatic shape of specimens has been chosen to ensure a planar surface necessary for accurate in-plane 2D-DIC measurements (Ferrero et al, 2008;Sutton et al, 2009). Extensive work has been performed using LUT as a tool for diagnosing the state of damage in various applications (Acosta-Colon et al, 2009;Cai & Zhao, 2000;Ghazvinian, 2015;Gheibi & Hedayat, 2018;Hedayat et al, 2014a;Hedayat et al, 2018;Hildyard et al, 2005;Huang et al, 2014;Jones, 1952;Modiriasari et al, 2017;Pyrak-Nolte, 1988;Sayers et al, 1990;Scott et al, 1993;Suaris & Fernando, 1987;Yang et al, 2018;Zhao et al, 2006). Significant efforts have been made to analytically model the effects of cracks and fractures on the ultrasonic wave propagation (Blum et al, 2011;Chaix et al, 2006;Crampin et al, 1980;De Basabe et al, 2016;Gross & Zhang, 1992;O'Connell & Budiansky, 1974;Hudson, 1981;Piau, 1979;Pyrak-Nolte et al, 1990a, 1990bWaterman & Truell, 1961;Yang & Turner, 2003).…”

From eggshells biowaste to hydroxyapatite biomaterial

“…The presence of such a large number of bioactive ions, and particularly the high magnesium content, makes eggshell an excellent precursor for the synthesis of the bioactive hydroxyapatite. Various methods of the hydroxyapatite synthesis have been developed, including: dry methods (solid-state synthesis and the mechanochemical process), wet methods (conventional chemical precipitation, hydrolysis method, hydrothermal method, emulsion method, sol-gel method and sonochemical method), hightemperature processes (combustion method and pyrolysis process), microwave processing, synthesis from biogenic sources, as well as combination procedures [1][2][3][4][5][6][9][10][11]. The chemical precipitation method has been the most popular one, since it's versatile and has certain economic advantages [12][13][14][15].…”