Punching Tests on Deformable Facing Structures: Numerical Analyses and Mechanical Interpretation

Anchored wire meshes, commonly adopted to stabilise potentially unstable slopes in granular soils, are composed of wire meshes, geosynthetics, anchorage bars/ties and spike steel plates. In many cases, this reinforcement system is employed as a “passive” reinforcement, i.e. it transfers loads to the unstable domain only when this develops irreversible displacements. During this displacement accumulation, complex interaction mechanisms between the deformable reinforcement system and the underlying material take place. To study these interaction mechanisms, a series of large displacement 3D FEM numerical analyses is performed. The mechanical behaviour of the material constituting the wire mesh and the soil is reproduced by means of elastic-perfectly plastic constitutive relationships. In particular, for the mesh a von Mises failure condition and an associated flow rule are employed, whereas for the soil a Mohr-Coulomb criterion and a non-associated flow rule. The constitutive parameters are calibrated on a series of experimental punching test results. The numerical results are reported by means of the characteristic curve, relating the penetration of the steel plate to the system reaction force. In order to stress the role of (i) both soil and wire mechanical behaviour and (ii) the spike plate dimensions in influencing the mechanical response of the whole system, the results of a parametric study are finally discussed.