Reinforced Drapery Meshes: A Design Method Accounting for Retaining Ropes Contribution

Abstract

Reinforced drapery meshes, both secured and pinned, constitute a compelling solution for rockfall risk mitigation on rock slopes facing structures and infrastructures. They consist of steel wire mesh panels combined with a systematic anchoring pattern. In secured drapery systems, the anchors are connected to each other and to the net through ropes. The system prevents both global instability of the surficial part of the slope thanks to the anchors and local instability by confining small detached fragments in delimited mesh sections. The mesh is generally designed with mechanical resistance derived from the puncturing force–displacement behavior observed during a standardized laboratory test. Despite the fact that a codified design method has not yet been defined, the mesh is generally verified without considering the presence of the ropes. In the present work, an enhanced design method is introduced that accounts for retaining ropes, with the aim of achieving a confining effect similar to the constraints adopted in laboratory tests. In addition, the rope pattern enables the consideration of portions of mesh smaller than pinned drapery systems. In the proposed method, rope elongation is limited such that failure of the mesh near the anchor plate is prevented. The proposed design assessment reveals that the presence of ropes provides possible cost reductions in the choice of the mesh type.

Towards a Hybrid Design Approach of Anchored Drapery Systems

“…Despite the strong simplifications made in the standard laboratory punch test procedure [7,18,19,35], the test is global and is used in the design phases of the pinned and secured drapery systems. The laboratory test procedure is defined by international and European standards [14-16], which are based on the Italian Standard UNI 11437 [17] (referred to as UNI).…”

“…The failure of the mesh is most frequently observed in proximity to the anchor plates [7,47] and this has been observed in numerical analyses [18,19]. Therefore, it is reasonable to assume that, for sufficiently large punching elements, the mesh resistance is controlled by the available resistance at the mesh-anchor connection, which, in turn, is a function of the number of wires intercepted by the anchor plate.…”

“…Despite anchored drapery systems being applied worldwide, their design is still mainly based on engineers' work experience. The few design approaches proposed in the literature [4][5][6][7] are based on limit equilibrium computations and differ in terms of failure mechanisms (i.e., local or global), slope type (i.e., soil-like or rock-like), and the eventual pre-tension of the mesh. Blanco-Fernandez et al [5] provided an overview of the existing design methods.…”