Influence of tectonic fractures zones on gravitational rock slope failures: New insights from 2-D physical modeling

International audienceInherited structural discontinuities are known to play a dominant role in rock slope stability. The influence of their density and persistence on failure kinematics, resulting mobilized volume and slope morphology remains poorly constrained. The influence of these parameters is addressed using a 2-D physical modeling technique. Rather than undertaking a parametric analysis, we examine geologically stable model configuration based upon the well-documented landslide at Randa, Switzerland. The models consisted of a homogeneous material in which several fracture zones were introduced in order to study simplified but realistic configurations of discontinuities. Results showed that the type of gravitational failure (deep-seated landslide or sequential failure) and resulting slope morphology are very sensitive to the number and geometry of preexisting fracture zones. First, an increase in the density of fractures led to formation of the gravitational failure and increased the final mobilized volume. Second, fracture persistence exerted a strong control upon the kinematics of slope movements but had little influence on the final volume of the mobilized mass