An innovative micromechanics-based three-dimensional long-term strength criterion for fracture assessment of rock materials

Abstract

ABSTRACT. Rocks may exhibit time-dependent behaviors. Long-term strength criterion significantly dominates creep failure of rocks. Rocks contain many microcracks, which lead to degrade of long-term strength. In this paper, it is assumed that there exist three-dimensional penny-shaped microcracks in rocks. The mode II stress intensity factors at tips of three-dimensional pennyshaped microcracks in Burgers viscoelastic rock matrix is derived. A novel micromechanics-based three-dimensional long-term strength criterion is established to consider the effects of time and the intermediate principal stress on creep failure of rocks. By comparison with the previous experimental data, it is found that the novel micromechanics-based threedimensional long-term strength criterion is in good agreement with the experimental data. KEYWORDS.Micromechanics-based three-dimensional long-term strength criterion; Burgers viscoelastic rock matrix; three-dimensional penny-shaped creep microcracks; Stress intensity factor; The intermediate principal stress.Citation: Zhou, X.-P., Huang, X.-C., Berto, F., An innovative micromechanics-based three-dimensional long-term strength criterion for fracture assessment of rock materials, Frattura ed Integrità Strutturale, 44 (2018) 64-81.

Modified Mohr–Coulomb criterion for nonlinear strength characteristics of rocks

“…More recently, the study of rock strength criterion has also been tackled from the micromechanical method and Refs. [24][25][26] provide an admirable summary of the application of the micromechanical method to strength criteria. There has deliberately established a dedicated scientific research team of the International Society of Rock Mechanics (ISRM), which is responsible for "Suggested Methods for Failure Criteria", working on the standardization of commonly used failure criteria and providing the ISRM members with specialized support about new progress.…”

“…In order to meet the growing demands of rock engineering, mining, and the energy industry, numerous strength criteria have been developed through continuous exploration by many scholars, such as the Griffith criterion, 19 Mohr–Coulomb criterion, 20 Drucker‐Prager criterion, 21 Hoek–Brown criterion, 22 as well as their enhancements, 23 etc. More recently, the study of rock strength criterion has also been tackled from the micromechanical method and Refs 24–26 . provide an admirable summary of the application of the micromechanical method to strength criteria.…”

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