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|Title:||Strain rate-dependent hardening-softening characteristics of gas hydrate-Bearing sediments||Authors:||Deusner, C
|Keywords:||Gas hydrate-bearing sediments
|Issue Date:||2019||Publisher:||Wiley published on behalf of American Geophysical Union||Source:||Geochemistry geophysics geosystems, 2019 , v. 20, no. 11, p. 4885-4905 How to cite?||Journal:||Geochemistry geophysics geosystems||Abstract:||The presence of gas hydrates (GHs) increases the stiffness and strength of marine sediments. In elasto-plastic constitutive models, it is common to consider GH saturation (S-h) as key internal variable for defining the contribution of GHs to composite soil mechanical behavior. However, the stress-strain behavior of GH-bearing sediments (GHBS) also depends on the microscale distribution of GH and on GH-sediment fabrics. A thorough analysis of GHBS is difficult, because there is no unique relation between S-h and GH morphology. To improve the understanding of stress-strain behavior of GHBS in terms of established soil models, this study summarizes results from triaxial compression tests with different S-h, pore fluids, effective confining stresses, and strain histories. Our data indicate that the mechanical behavior of GHBS strongly depends on S-h and GH morphology, and also on the strain-induced alteration of GH-sediment fabrics. Hardening-softening characteristics of GHBS are strain rate-dependent, which suggests that GH-sediment fabrics dynamically rearrange during plastic yielding events. We hypothesize that rearrangement of GH-sediment fabrics, through viscous deformation or transient dissociation and reformation of GHs, results in kinematic hardening, suppressed softening, and secondary strength recovery, which could potentially mitigate or counteract large-strain failure events. For constitutive modeling approaches, we suggest that strain rate-dependent micromechanical effects from alterations of the GH-sediment fabrics can be lumped into a nonconstant residual friction parameter. We propose simple empirical evolution functions for the mechanical properties and calibrate the model parameters against the experimental data.||URI:||http://hdl.handle.net/10397/81724||EISSN:||1525-2027||DOI:||10.1029/2019GC008458||Rights:||©2019. The Authors.
This is an open access article under theterms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits use,distribution and reproduction in anymedium, provided the original work isproperly cited.
The following publication Deusner, C., Gupta, S., Xie, X.‐G.,Leung, Y. F., Uchida, S., Kossel, E., & Haeckel, M. (2019). Strainrate‐dependent hardening‐softeningcharacteristics of gas hydrate‐bearingsediments. Geochemistry, Geophysics, Geosystems, 20 (11), 4885–4905 is available at https://dx.doi.org/10.1029/2019GC008458
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