Abstract:
Anchored wire mesh is frequently used as passive stabilizing systems for potentially unstable slopes. The stability of the slope is achieved by the introduction of reinÂforcement anchor bars. When displacement of the soil occurs, these anchors help improve stability conditions by mobilizing friction forces along its enÂtire length. The protection of the exposed surface of the reinforced soil slope is essential and is achieved using a facing element. This facing can be solid, like shotcrete, or flexible, like a steel wire mesh and it is responsible to contain the soil between the nails and preÂvent erosion of the surface. The stabilizing action is a result to an intricate relation of such elements with the underlying unstable layer, which is influenced by the geometry of the slope, the stabilizing intervention, mechanical characteristics of the soil and mesh, and the intensity and time variability of applied loads. Conventional design methodologies rely on an Ultimate Limit State hypothesis (ULS), assuming the full mobilization of the ultimate soil resistance and the complete activation of the ultimate tensile force in the wire mesh facing. Such an assumption is counterintuitive to the concept of flexible facing systems and can potentially lead to an unsafe design. The stabilization action of passive systems is only mobilized when soil displacement occurs. An innovative "hybrid" method that combines a ULS analysis of the unstable soil slope with a Serviceability Limit State analysis (SLS) for the stabilizing elements is presented in this study. It is based on advancements in design methods for wire mesh slope stabilization systems. This hybrid approach proves a wire mesh working ratio and enables the influence of both its strength and stiffness to be systematically determined. It also enables the designer to easily and consistently estimate the effect of soil displacement on the factor of safety of the slope.