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- Title
A Comparative Study of Current Methods for Determining Stress Thresholds of Rock Subjected to Compression.
- Authors
Zhang, Zhenghu; Liang, Zhengzhao; Tang, Chun'an; Kishida, Kiyoshi
- Abstract
There are four essential stress thresholds for the progressive failure of rock subjected to compressive loading, i.e., the peak strength (PS), crack damage stress (CD), crack initiation stress (CI) and crack closure stress (CC). Accurate values for these stress thresholds have important implications for rock mechanics and engineering geology. Here, first, current approaches for determining stress thresholds of rock were introduced and systematically reviewed. Subsequently, uniaxial compression was used in a series of laboratory tests on five common rocks including igneous, sedimentary and metamorphic rocks. Additionally, acoustic emission (AE) monitoring was conducted to analyse AE-based methods for determining the CI. The current methods were then compared. The pros and cons of these methods were discussed from the five perspectives of computational simplicity, solution stability, solution objectivity or uniqueness, clarity of physical meaning and universal applicability. The results showed two cases according to whether the volume strain curve had an inflection point. In both cases, the CD was calculated as the applied stress to the rock at the maximum volume strain. Among all ten methods, the lateral strain response (LSR) and the relative compression strain response (RCSR) were recommended for evaluating the CI. Among the five current methods, the compression coefficient response (CCR) was recommended to calculate the CC. The relationships between the CD, CI, CC and UCS values were strongly linear for different rocks. Ratios of stress thresholds for common brittle rocks, namely, CC/PS, CI/PS and CD/PS, were on average approximately 0.93, 0.60 and 0.17 based on the results of linear fits. These findings could be helpful in studies to select an appropriate approach for determining rock stress thresholds and, hence, to better evaluate the stability of rock-related engineering structures. Highlights: A comparison of current methods for determining rock stress thresholds was made from the five perspectives of computational simplicity, solution stability, solution objectivity, clarity of physical meaning and universal applicability. Regardless of whether the volume strain curve had an inflection point, the crack damage stress was calculated as the applied stress to the rock at the maximum volume strain. Among all ten methods, the lateral strain response and the relative compression strain response were recommended for evaluating the crack initiation stress. Among the five methods, the compression coefficient response was recommended to calculate the crack closure stress.
- Subjects
CRACK closure; IGNEOUS rocks; ENGINEERING geology; METAMORPHIC rocks; SEDIMENTARY rocks; ECCENTRIC loads
- Publication
Rock Mechanics & Rock Engineering, 2023, Vol 56, Issue 11, p7795
- ISSN
0723-2632
- Publication type
Article
- DOI
10.1007/s00603-023-03480-3