Abstract
Crack damage leading to failure in rocks can be accumulated through cyclic stressing in the crust. However, the vast majority of experimental studies to investigate cyclic stresses apply conventional triaxial stress states (σ1 > σ2 = σ3), while in nature the state-of-stress in the crust is generally truly triaxial (σ1 > σ2 > σ3). Furthermore, the magnitude of these crustal stresses can vary over time and their orientations can also rotate over time, generating multiple crack populations and bulk anisotropic crack damage. We investigate the evolution of crack damage under both conventional and true triaxial stress conditions by sequentially and cyclically varying stresses in all three principal directions on cubic samples of dry sandstone using independently controlled stress paths. We have measured, simultaneously with stress, the bulk acoustic emission (AE) output, as a proxy for crack damage. We report a directionally controlled crack damage memory effect which has implications for the approach to failure in complex tectonic stress environments.
Original language | English |
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Pages (from-to) | 6878-6886 |
Number of pages | 9 |
Journal | Geophysical Research Letters |
Volume | 45 |
Issue number | 14 |
Early online date | 2 Jul 2018 |
DOIs | |
Publication status | Published - 28 Jul 2018 |
Bibliographical note
We thank J.G. Van Munster for providing access to the true triaxial apparatus at KSEPL and for technical support during the experimental program. This work was partly funded by NERC awards NE/N002938/1, NE/N003063/1, and by a NERC Doctoral Studentship, which we gratefully acknowledge. Supporting data are included in an SI file; any additional data may be obtained from JB (email: j.browning@ucl.ac.uk).Keywords
- triaxial
- crack damage
- Kaiser effect
- stress rotation
- stress memory