Slow Dynamics and Strength Recovery in Unconsolidated Granular Earth Materials: A Mechanistic Theory
| Autor: | Eric G. Daub, Robert E. Ecke, Charles K. C. Lieou, Paul A. Johnson |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
010504 meteorology & atmospheric sciences
Dynamics (mechanics) Modulus Earth materials Mechanics Granular material 01 natural sciences Nonlinear system Geophysics Space and Planetary Science Geochemistry and Petrology Fault gouge 0103 physical sciences Earth and Planetary Sciences (miscellaneous) Relaxation (physics) Geotechnical engineering 010306 general physics Elastic modulus Geology 0105 earth and related environmental sciences |
| Zdroj: | Journal of Geophysical Research: Solid Earth. 122:7573-7583 |
| ISSN: | 2169-9313 |
| Popis: | Rock materials often display long-time relaxation, commonly termed aging or “slow dynamics”, after the cessation of acoustic perturbations. In this paper, we focus on unconsolidated rock materials and propose to explain such nonlinear relaxation through the Shear-Transformation-Zone (STZ) theory of granular media, adapted for small stresses and strains. The theory attributes the observed relaxation to the slow, irreversible change of positions of constituent grains, and posits that the aging process can be described in three stages: fast recovery before some characteristic time associated with the subset of local plastic events or grain rearrangements with a short time scale, log-linear recovery of the elastic modulus at intermediate times, and gradual turnover to equilibrium steady-state behavior at long times. We demonstrate good agreement with experiments on aging in granular materials such as simulated fault gouge after an external disturbance. These results may provide insights into observed modulus recovery after strong shaking in the near surface region of earthquake zones. |
| Databáze: | OpenAIRE |
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