Rock joints modeling and application to scale effects, improvements

Scale effect is a phenomenon of increasing importance in rock mechanics and particularly in the field of rock joints, and as large scale experiments are difficult to handle, numerical modeling can be considered as an alternative way to study the macro joints mechanical behavior. A meso joint constitutive behavior model including an original dilatancy angle evolution law and an original rupture mechanism has previously been presented. This paper presents some improvements made on the previously developed model for large shear displacement of rock joints, and presents some results obtained using an originally developed finite displacement concept, taking in account the local opening phenomenon and the physical interactions. The results indicate changes in the dilation curves, peak shear stress decrease, initial shear stiffness decrease and peak shear displacement increase with joint size for shearing at constant normal stress. The results show a stabilization of the scale effect for macro joints of more than two meters.