A Strain Based Method for Determining the Crack Closure and Initiation Stress in Compression Tests
- 13 Downloads
The pre-peak loading stages of rock in compression tests are divided into four stages (i.e., crack closure, elastic deformation, stable crack growth and unstable crack growth) by identifying the Crack Closure stress (CC), Crack Initiation stress (CI), and crack damage stress. A new method for determining the CC and CI is presented in this paper and compared with previous methods. The new method is called “Continuous Strain Deviation” (CSD), and it solves two problems associated with other methods: 1) determining the limits for the elastic range in laboratory data, and 2) identifying where crack closure or initiation occurs from the subtle changes in the stress-strain data. Starting from an initial point corresponding to 30% to 40% UCS, the proposed algorithm provides a distinct indicator for CC and CI. The CC and CI for Badaling granite and Äspö diorite are determined with the proposed method, results from which are similar to other methods. Sensitivity analyses of the CSD method show that stable CC and CI values could be estimated using any initial point from 30% to 40% UCS. Comparison studies show that the CSD method predicts a smaller stress range and gives a more distinct indicator for both CC and CI.
Keywordscrack initiation crack closure spalling continuous strain deviation brittle rocks compression tests
Unable to display preview. Download preview PDF.
- Andersson, J. C., Martin, C. D., and Stille, H. (2009). “The Äspö pillar stability experiment: Part II—Rock mass response to coupled excavation–induced and thermal–induced stresses.” International Journal of Rock Mechanics and Mining Sciences, vol. 46, no. 5, pp. 879–895, DOI: 10.1016/j.ijrmms.2009.03.002.CrossRefGoogle Scholar
- Cai, M., Kaiser, P. K., Tasaka, Y., Maejima, T., Morioka, H., and Minami, M. (2004). “Generalized crack initiation and crack damage stress thresholds of brittle rock masses near underground excavations.” International Journal of Rock Mechanics and Mining Sciences, vol. 41, no. 5, pp. 833–847, DOI: 10.1016/j.ijrmms.2004.02.001.CrossRefGoogle Scholar
- Diederichs, M. S., Kaiser, P. K., and Eberhardt, E. (2004). “Damage initiation and propagation in hard rock during tunnelling and the influence of near–face stress rotation.” International Journal of Rock Mechanics and Mining Sciences, vol. 41, no. 5, pp. 785–812, DOI: 10.1016/j.ijrmms.2004.02.003.CrossRefGoogle Scholar
- Glamheden, R., Fälth, B., Jacobsson, L., Harrström, J., Berglund, J., and Bergkvist, L. (2010). Counterforce applied to prevent spalling, Technical Report SKB TR–10–37, Swedish Nuclear Fuel and Waste Management, Stockholm, Sweden.Google Scholar
- Kaiser, P. K., Yazici, S., and Maloney, S. (2001). “Mining–induced stress change and consequences of stress path on excavation stability–a case study.” International Journal of Rock Mechanics and Mining Sciences, vol. 38, no. 2, pp. 167–180, DOI: 10.1016/S1365–1609 (00)00038–1.CrossRefGoogle Scholar
- Martin, C. D., Kaiser, P. K., and McCreath, D. R. (1999). “Hoek–Brown parameters for predicting the depth of brittle failure around tunnels.” Canadian Geotechnical Journal, Vol. 36, No.1, pp. 136–151, DOI: 10.1139/t98–072.Google Scholar
- Tkalich, D., Fourmeau, M., Kane, A., Li, C. C., and Cailletaud, G. (2016). “Experimental and numerical study of Kuru granite under confined compression and indentation.” International Journal of Rock Mechanics and Mining Sciences, vol. 87, pp. 55–68, DOI: 10.1016/j.ijrmms.2016.05.012.CrossRefGoogle Scholar