AN EXTENSION TO THE SAEB AND AMADEI CONSTITUTIVE MODEL FOR ROCK JOINTS TO INCLUDE CYCLIC LOADING PATHS

Joints in a given rock mass are subjected to a wide variety of boundar y conditions and also to various cycles of loading and unloading in bo th normal and shear directions. This paper presents an extension of th e Saeb and Amadei model to take into account joint loading and unloadi ng in both normal and shear directions. In the normal direction, the c yclic behavior is hyperbolic and the irrecoverable normal closure depe nds on the joint loading history. Concerning the shear direction chang e, two assumptions are supposed: the pre-peak behavior is elastic; and , during the residual behavior, the joint is smooth (all the asperitie s ave 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 veri fied using existing experimental results.