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Geomechanics and Engineering
  Volume 24, Number 4, February25 2021 , pages 307-321

Theoretical model for the shear strength of rock discontinuities with non-associated flow laws
Ruben Galindo, Jose L. Andres, Antonio Lara, Bin Xu, Zhigang Cao and Yuanqiang Cai

    In an earlier publication (Serrano et al. 2014), the theoretical basis for evaluating the shear strength in rock joints was presented and used to derive an equation that governs the relationship between tangential and normal stresses on the joint during slippage between the joint faces. In this paper, the theoretical equation is applied to two non-linear failure criteria by using non-associated flow laws, including the modified Hoek and Brown and modified Mohr-Coulomb equations. The theoretical model considers the geometric dilatancy, the instantaneous friction angle, and a parameter that considers joint surface roughness as dependent variables. This model uses a similar equation structure to the empirical law that was proposed by Barton in 1973. However, a good correlation with the empirical values and, therefore, Barton's equation is necessary to incorporate a non-associated flow law that governs breakage processes in rock masses and becomes more significant in highly fractured media, which can be induced in a rock joint. A linear law of dilatancy is used to assess the importance of the non-associated flow to obtain very close values for different roughness states, so the best results are obtained for null material dilatancy, which considers significant changes that correspond to soft rock masses or altered zones of weakness.
Key Words
    rock joint; shear strength; theoretical model; dilatancy; non-linear criterion; non-associated flow law
Ruben Galindo, Jose L. Andres and Antonio Lara: Department of Geotechnical Engineering, Technical University of Madrid, C/ Profesor Aranguren s/n 28040 Madrid, Spain

Bin Xu, Zhigang Cao and Yuanqiang Cai: Department of Civil Engineering, College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310058, PR China

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