Linear failure criterion for estimating the compressive strength of brittle foliated rocks in response to the loading direction

• Published in: Bulletin of engineering geology and the environment Vol. 81; no. 5
• Main Authors: Yin, Xiaomeng, Zhang, Yage, Lei, Yuju, Wang, Lunan
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.05.2022
• Subjects: Earth and Environmental Science; Earth Sciences; Foundations; Geoecology/Natural Processes; Geoengineering; Geotechnical Engineering & Applied Earth Sciences; Hydraulics; Nature Conservation; Original Paper; Foliated rocks; Compression failure mode; Failure criterion; Fabric
• ISSN: 1435-9529; 1435-9537
• DOI: 10.1007/s10064-022-02681-4

In this study, a failure criterion is proposed for describing the strength variation of foliated rocks that possess inherently anisotropic properties due to the existence of macro weak planes (MWPs). These rocks are typically characterized by the clustering and directional arrangement of needle-flaky minerals, a quasi-interlayered structure composed of weak and strong layers, and a directional arrangement of microcracks. The compressive failure mode of foliated rocks subjected to confining pressure is heavily dependent on the loading direction, which can be divided into two types within a certain range of confining pressures: shear-slip failure along the MWP and macro shear failure oblique to the MWP. From the perspective of the failure mechanism related to rock fabric and macrofailure characteristics, the linear failure criteria available for the two modes are proposed based on fracture mechanics theory, the Mohr–Coulomb criterion and the maximum axial strain criterion. The criteria involve 6 parameters that can be simply determined by a small amount of test data. Among them, the friction coefficient f is closely related to the loading direction corresponding to the minimum compressive strength, and the transversely isotropic parameter n controls the variation form of anisotropic strength with the loading direction. The predicted values of several kinds of exemplary foliated rocks agree well with their measured compressive strengths depending on the confining pressure and loading direction, suggesting a high prediction accuracy for the new criterion. The analysis reveals that the new criterion is suitable for describing the failure of brittle foliated rocks within a certain range of confining pressures.