Abstract
Quasi-static rock strength is a nonconservative property, as fatigue during cyclic loading reduces the macroscopic strength. When strain rate under compressive loading increases above a lithology-specific threshold, the primary failure mechanism transitions from localized failure along discrete fractures to distributed fracturing. However, the role of load path under high strain rate conditions has not been explored in any detail. We examine the effect of rapid stress cycles on the dynamic compressive strength of Westerly Granite using a modified split Hopkinson pressure bar approach and explore the implications of our results for the formation of pulverized fault zone rocks. Under cyclic loading conditions, the compressive strength can be reduced by a factor of 2, demonstrating that, like the quasi-static strength, the dynamic rock strength is also a nonconservative property. Therefore, traditional high strain rate experimental approaches utilizing simple load paths may overestimate strength when rocks are subjected to complex load paths.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 6479-6486 |
| Number of pages | 8 |
| Journal | Geophysical Research Letters |
| Volume | 46 |
| Issue number | 12 |
| DOIs | |
| State | Published - Jun 28 2019 |
| Externally published | Yes |
Bibliographical note
Funding Information:This research was sponsored by the National Science Foundation under award EAR 1351931 to Griffith and Army Research Office under grant W911NF‐14‐1‐0876 to Griffith. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Army Research Laboratory or the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation herein. We thank Chris Borjas, Troy Barber, Hamed Ghaffari, Brooke Parsons, and Tootie Kassimu for their valuable insights, discussions, and preliminary work at the start of this project. We also acknowledge Kermit Beird and Larry Antal for their assistance in sample preparation. All data pertaining to this paper, including SHPB voltage time series and high‐ speed camera videos, are available at this site (https://doi.pangaea.de/ 10.1594/PANGAEA.901316).
Funding Information:
This research was sponsored by the National Science Foundation under award EAR 1351931 to Griffith and Army Research Office under grant W911NF-14-1-0876 to Griffith. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Army Research Laboratory or the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation herein. We thank Chris Borjas, Troy Barber, Hamed Ghaffari, Brooke Parsons, and Tootie Kassimu for their valuable insights, discussions, and preliminary work at the start of this project. We also acknowledge Kermit Beird and Larry Antal for their assistance in sample preparation. All data pertaining to this paper, including SHPB voltage time series and high-speed camera videos, are available at this site (https://doi.pangaea.de/10.1594/PANGAEA.901316).
Publisher Copyright:
©2019. American Geophysical Union. All Rights Reserved.
Keywords
- experimental rock mechanics
- fragmentation
- pulverized rocks
- split Hopkinson pressure bar
- stress cycling