کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
809542 | 1468713 | 2012 | 15 صفحه PDF | دانلود رایگان |

Existing experimental evidence from true triaxial test (also referred to as poly-axial test) indicates that the influence of the intermediate principal stress (σ2) on rock strength is substantial. In order to consider this effect in rock engineering design, an adequate 3D failure criterion, which takes into account the effect of σ2, is required. Such a criterion should not only be a convex but also a smooth function of stress state; the latter to avoid singularities and to ensure the numerical stability. The most popular failure criteria used in rock mechanics, i.e., Mohr–Coulomb (M–C) and Hoek–Brown (H–B), both ignore the effect of σ2 and also have singular corners. Hence, in this paper, the M–C and H–B criteria are modified to their 3D versions based on geometric approximations of deviatoric sections that lead to smooth and convex surfaces for a wide range of strength parameters. The derived criteria inherit all the key properties of the original ones and are formulated in terms of stress invariants introduced by Nayak and Zienkiewicz. The latter provides an easy way to identify the strength parameters from non-linear multiple regression analysis using the poly-axial test data. In order to validate the proposed criteria, eight sets of poly-axial tests selected from literature are fitted. The results clearly show that the new criteria are quite accurate for all rock types considered. Finally, an extension of the proposed criteria to account for anisotropic rock conditions is discussed and an illustrative example is provided incorporating the functional forms of H–B and modified H–B criteria.
► The M–C and H–B criteria are modified to their 3D versions.
► The new criteria are smooth and convex in the principal stress space.
► The proposed criteria are validated by fitting eight sets of polyaxial test data.
► Non-linear multiple regression is performed for finding the best-fitting parameters.
► Potential extension of the proposed criteria to anisotropic versions is discussed.
Journal: International Journal of Rock Mechanics and Mining Sciences - Volume 56, December 2012, Pages 146–160