Monitoring Local Changes in Granite Rock Under Biaxial Test: A Spatiotemporal Imaging Application With Diffuse Waves

Abstract

Diffuse acoustic or seismic waves are highly sensitive to detect changes of mechanical properties in heterogeneous geological materials. In particular, thanks to acoustoelasticity, we can quantify stress changes by tracking acoustic or seismic relative velocity changes in the material at test. In this paper, we report on a small‐scale laboratory application of an innovative time‐lapse tomography technique named Locadiff to image spatiotemporal mechanical changes on a granite sample under biaxial loading, using diffuse waves at ultrasonic frequencies (300 kHz to 900 kHz). We demonstrate the ability of the method to image reversible stress evolution and deformation process, together with the development of reversible and irreversible localized microdamage in the specimen at an early stage. Using full‐field infrared thermography, we visualize stress‐induced temperature changes and validate stress images obtained from diffuse ultrasound. We demonstrate that the inversion with a good resolution can be achieved with only a limited number of receivers distributed around a single source, all located at the free surface of the specimen. This small‐scale experiment is a proof of concept for frictional earthquake‐like failure (e.g., stick‐slip) research at laboratory scale as well as large‐scale seismic applications, potentially including active fault monitoring.

Changes in resonance frequency of rock columns due to thermoelastic effects on a daily scale: observations, modelling and insights to improve monitoring systems

“…Such changes in mechanical strain or stress field cause variations of wave velocity propagating through the medium. This relation forms the basis of acousto-elasticity, which has been extensively described both theoretically and experimentally (Murnaghan 1951, Bach & Askegaard 1979, Larose & Hall 2009, Tsai 2011, Xie et al 2018. For most materials, additional stress causes higher rigidity leading to an increase in wave velocity (Planès & Larose 2013).…”

Initial Acoustoelastic Measurements in Olivine: Investigating the Effect of Stress on P‐ and S‐Wave Velocities

“…Previous geologic studies have derived the third-order elastic constants, using the theory of acoustoelasticity, for various sedimentary, igneous, and metamorphic rocks. The experiments in these studies are typically performed at ambient to low confining pressures (Liu et al, 2007;Lucet, 1989;Nur & Simmons, 1969;Winkler & Liu, 1996;Xie et al, 2018;Zamora, 1990). Johnson and Rasolofosaon (1996) used the finite elastic deformation theory of Murnaghan (1951) to describe stress-induced velocity changes from published experimental data for sandstone and marble (Zamora, 1990), Barre granite (Nur & Simmons, 1969), and Bauvilliers limestone (Lucet, 1989).…”

“…Previous geologic studies have derived the third‐order elastic constants, using the theory of acoustoelasticity, for various sedimentary, igneous, and metamorphic rocks. The experiments in these studies are typically performed at ambient to low confining pressures (Liu et al., 2007; Lucet, 1989; Nur & Simmons, 1969; Winkler & Liu, 1996; Xie et al., 2018; Zamora, 1990).…”

Quantitative evaluation of bolt connection using a single piezoceramic transducer and ultrasonic coda wave energy with the consideration of the piezoceramic aging effect

“…Therefore, the diffuse ultrasound based on CWI analysis makes it possible to study stress-induced changes within small perturbations. At present, coda wave is mostly used to evaluate non-uniformity of rock in the geophysics context [59][60][61][62][63][64] and NDT of concrete structures [58], and no related paper has been reported in bolt tightening monitoring. Due to the high sensitivity to the detection of heterogeneity, coda wave can be used to evaluate the heterogeneity of the rough surface which reflects the magnitude of the pre-tightening force of the bolt.Therefore, bolted connection can be characterized by the coda wave.…”