In situ characterization of shallow elastic nonlinear parameters with Dynamic Acoustoelastic Testing

G. Renaud, J. Rivière, C. Larmat, J. T. Rutledge, R. C. Lee, R. A. Guyer, K. Stokoe, P. A. Johnson

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

In situ measurement of the elastic nonlinear site response is advantageous to provide optimal information for prediction of strong ground motion at a site. We report the first implementation of a technique known as Dynamic Acoustoelastic Testing (DAET) in situ with the ultimate goal of developing a new approach for site characterization. DAET has shown promising results at the laboratory scale for the study of nonlinear elasticity of Earth materials, detailing the full nonlinear elastic properties of the studied sample. We demonstrate the feasibility of DAET in situ and compare it to other methods (nonlinear resonance spectroscopy, wave amplitude dependence of propagation velocity, and wave distortion). Nonlinear elastic properties are characterized by DAET with the advantage of providing a local assessment compared to other methods, here at a depth of 4 m to 5 m. A vertical dynamic strain amplitude of 5 ×10-5 produces a relative change in compressional wave modulus of 6%. We measure an effective parameter of quadratic elastic nonlinearity of order -103, the same order of magnitude measured at the laboratory scale in rocks and in packs of unconsolidated glass beads. Hysteresis is observed in the variation in soil elasticity as a function of the instantaneous dynamic strain that evolves as the dynamic strain amplitude is increased from 9 ×10-7 to 5 ×10-5. Key Points First implementation of Dynamic Acoustoelastic Testing (DAET) in situNonlinear elastic parameters of soil can be measured in situDAET is promising for in situ measurement of the nonlinear site response

Original languageEnglish (US)
Pages (from-to)6907-6923
Number of pages17
JournalJournal of Geophysical Research: Solid Earth
Volume119
Issue number9
DOIs
StatePublished - Sep 1 2014

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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