An extension to the Saeb and Amadei constitutive model for rock joints to include cyclic loading paths

Abstract

Joints in a given rock mass are subjected to a wide variety of boundary conditions and also to various cycles of loading and unloading in both normal and shear directions. This paper presents an extension of the Saeb and Amadei model to take into account joint loading and unloading in both normal and shear directions. In the normal direction, the cyclic behavior is hyperbolic and the irrecoverable normal closure depends on the joint loading history. Concerning the shear direction change, two assumptions are supposed: the pre-peak behavior is elastic; and, during the residual behavior, the joint is smooth (all the asperities are crushed) and the shear band developed by these fragments is not taken into account. Finally the applicability of the proposed model to predict the behavior of a joint under loading-unloading paths is verified using existing experimental results.