Abstract

Application of mechanical stresses to soil results in deformation, micro-fracturing, particle motion, and liquid reconfiguration that may release measurable amounts of stored elastic energy in the form of acoustic emissions (AEs). This study aimed to systematically study AE characteristics during confined uniaxial compression of soil samples and link various AE parameters to soil deformation regimes. We hypothesized that variations in AE characteristics could offer new insights into the transition between elastic and plastic soil deformation and noninvasively identify the onset of yield stress. We subjected soil samples at known water contents to a loading-unloading-reloading cycle under uniaxial compression using an oedometer coupled with an AE monitoring system. The soil was a sandy loam equilibrated with two initial gravimetric water contents (12 and 25%) and two initial bulk densities (1.3 and 1.55 Mg m(-3)) for each water content. Observed AE event numbers (hits) and their energy content (E) varied during stress application to soil samples. Close agreement was found between soil yield stress deduced from normalized cumulative AE parameters and measured stress-void ratio curves (precompression stress, sigma(pc)) for the dry soil; however, the yield stress deduced from AE parameters was significantly larger than sigma(pc) for the wet soil. Swelling and compression indices were strongly correlated to AE hits and E, respectively. The preliminary results illustrate the potential of monitoring passive AE during load application to characterize soil mechanical parameters (potentially in situ). Nevertheless, additional studies with controlled pore water pressure and a range of soil types would be required to generalize these findings to offer a robust AE-based method.

Published in

Vadose Zone Journal
2017, Volume: 16, number: 7
Publisher: SOIL SCI SOC AMER

SLU Authors

• Keller, Thomas

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    
  • Agroscope

Sustainable Development Goals

SDG15 Protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss


UKÄ Subject classification

Soil Science


Publication identifier

DOI: https://doi.org/10.2136/vzj2017.02.0049

Permanent link to this page (URI)

https://res.slu.se/id/publ/87139