Issue 47

M. Marchelli et alii, Frattura ed Integrità Strutturale, 47 (2019) 437-450; DOI: 10.3221/IGF-ESIS.47.34

are present, increasing the adhesion of the net to the slope, but without other specific structural aim. The mesh has to resist tangential and normal forces induced by falling blocks that can tear or puncture the mesh. Reinforced drapery meshes (Fig. 1.b) are essentially made in the same way as the simple meshes. Besides, additional metallic ropes fixed to the cliff through a regular pattern of bolts enforce the adhesion of the net to the rock face. This system allows the small falling blocks to be collected into delimited sectors of the mesh and increases the stability of the fragmented face through the bolts, i.e. exerting an active role.

(a) Simple drapery net

(b) Reinforced drapery net

Figure 1 : Views and sketches of (a) the simple drapery net and (b) the reinforced drapery net installations. Note that the reinforced drapery net follows the shape of the cliff face.

The performance of the previously described systems depends on the adopted solutions for the mesh, the ropes, and the anchors. Nets are made of steel wire meshes, which can be single-twisted rhomboidal or double twisted hexagonal. Other solutions consist in cable net panels made of metallic cables, connected with clips or knots, or ring net panels, laced together with steel cables or other devices. Usually, cable net is combined with wire mesh to intercept smaller blocks. Panels are

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