Abstract
AbstractBrittle deformation in rocks depends upon loading rate; with increasing rates, typically greater than ~102 s−1, rocks become significantly stronger and undergo increasingly severe fragmentation. Dynamic conditions required for rate‐dependent brittle failure may be reached during impact events, seismogenic rupture, and landslides. Material characteristics and fragment characterization of specific geomaterials from dynamic loading are only approximately known. Here we determine the characteristic strain rate for dynamic behavior in felsic crystalline rocks, including anisotropy, and describe the resulting fragments. Regardless of the type of felsic crystalline rock or anisotropy, the characteristic strain rate is the same within uncertainties for all tested materials, with an average value of 229 ± 81 s−1. Despite the lack of variation of the critical strain rate with lithology, we find that the degree of fragmentation as a function of strain rate varies depending on material. Scaled or not, the fragmentation results are inconsistent with current theoretical models of fragmentation. Additionally, we demonstrate that conditions during impact cratering, where the impactor diameter is less than ~100 m, are analogous to the experiments carried out here and therefore that dynamic strengthening and compressive fragmentation should be considered as important processes during impact cratering.
Highlights
Rock strength and fragmentation during dynamic deformation is critically controlled by strain rate (Aben et al, 2017; Ramesh et al, 2015)
We demonstrate that conditions during impact cratering, where the impactor diameter is less than ~100 m, are analogous to the experiments carried out here and that dynamic strengthening and compressive fragmentation should be considered as important processes during impact cratering
Kumar (1968) found that dynamic strength increase of granite occurred at loading rates greater than ~700 GPa s−1 which, for the elastic modulus of the Malsburg Granite, corresponds to a strain rate of ~20 s−1
Summary
Rock strength and fragmentation during dynamic deformation is critically controlled by strain rate (Aben et al, 2017; Ramesh et al, 2015). In failure, increased loading rates result in increased fragmentation of the material and may cause rock pulverization (Aben et al, 2016; Barber & Griffith, 2017; Doan & Gary, 2009; Ghaffari et al, 2019; Yao et al, 2020; Yuan et al, 2011). Fractures propagate at a finite velocity; at high loading rates, the weakest flaws in a material are not able to cause failure before other, increasingly strong flaws are activated (Aben et al, 2017; Ramesh et al, 2015)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
