Stability of jointed rock masses evaluated by UDEC with an extended Saeb-Amadei constitutive law

This paper discusses the results of a numerical study which examines the influence of the choice of joint constitutive model on the stability of jointed rock masses. In the two-dimensional code of the Distinct Element Method used for this study, UDEC, the mechanical behaviour of rock joints is represented by an elasto-plastic law and the empirical continuous-yielding law. The modified version of the Saeb and Amadei non-linear model for rock joints subjected to monotonic and cyclic loading sequences as proposed by Souley et al. Int. J. Rock Mech. Min. Sci. & Geomech. Abstr. 32, 101-109 (1995), is implemented in UDEC. Two simple examples provided a verification of the implemented model. These involved the monotonic normal compression of a joint and the direct shear test. The influence of joint constitutive law on the stability of an underground cavity was then examined for a specific joint network geometry. This analysis involved in situ low, medium, and high stress fields. Interpretation of the results shows that while stress magnitudes depend little on the type of constitutive law, the displacement field is, on the contrary, constitutive law dependent, particularly at high stress levels.