Abstract
A new method is proposed in order to estimate the shear strength of schistosity planes in slate in terms of Mohr–Coulomb cohesion and internal friction angle. The procedure consists in carrying out the Brazilian method under different loading-foliation angles, for which experimental tests were achieved in slates from the northwest of the Iberian Peninsula (Spain). The experimental fracture patterns were analytically studied and justified by simulating the stress field in the discontinuity planes contained in the whole sample, taking into account the first failure registered in the tests. By combining experimental and analytical studies and a procedure based on the representation of the threshold state of stresses—in the elastic regime—in the failure plane, it is possible to estimate the foliation’s strength envelope through a lineal adjustment according to the Mohr–Coulomb criterion and, thus, to characterize the layering. Finally, the proposed procedure was validated by the direct shear test. The cohesion and the internal friction angle obtained with this convenctional test were very close to that calculated by the proposed method, verifying the methodology developed by the authors. This procedure may be interesting in various engineering applications, either in the study of the properties of cleavage in slate, which is commonly used as an industrial rock, or in dam foundations, underground excavations and slope engineering, since one of the main failures in civil engineering is due to sliding along weak planes.
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Acknowledgements
The authors of this paper would like to acknowledge the financial support of the PhD fellowship Severo Ochoa Program of the Government of the Principality of Asturias (PA-14-PF-BP14-067). Also, the authors are grateful to editors and reviewers for their suggestions and help us to improve this manuscript.
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Garcia-Fernandez, C.C., Gonzalez-Nicieza, C., Alvarez-Fernandez, M.I. et al. New methodology for estimating the shear strength of layering in slate by using the Brazilian test. Bull Eng Geol Environ 78, 2283–2297 (2019). https://doi.org/10.1007/s10064-018-1297-3
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DOI: https://doi.org/10.1007/s10064-018-1297-3