RINA - Démonstrateur d’utilisation de l’intelligence artificielle pour la gestion opérationnelle des risques naturels gravitaires géologiques | FEREC 2020

Protective elements Rock falls are destructive events that cause damages and casualties. Diminishing the impact caused by this phenomena can be done by avoiding areas with high risk, by eliminating the hazard and by constructing protective structures (Wyllie 2014). Blocks fall from bedrocks with steep slopes. Knowing that there is a possibility of masses of rock falling from the bedrock, avoiding building roads and houses beneath it would avoid negative consequences. Paths that are already built can be redirected, protected or temporarily closed when the risk is higher (or a combination of all these solutions). Detailed analysis of cliffs may present volumes which are unstable and with high probability of collapse. In order to avoid damage it can be purged. This way they can be removed in a controlled manner and will not cause any negative impact. It is important to note that, by removing unstable blocks the bedrock behind it may become unstable. Protective structures are separated into two groups, active and passive. Active structures will hold blocks on the cliff and prevent them from falling. Passive structures will stop or deviate the rocks that fell from the cliff in order to prevent them from reaching the stakes. Active protective structures are implemented directly on the bedrock. The most common is the implementation of a steel net that is attached on the bedrock with soil nails [Figure 1.a]. Soil nails can be used without the net in order to hold single blocs. Passive protections are generally walls or ditches to stop the propagation of the rocks. This wall can be a steel net Figure 1.b, similar to the one used for active protection, but can also be an embankment which could be made of gabions, reinforced soil or a mixture of materials Figure 2.a. A ditch can also be excavated in order to stop the blocs on their path Figure 2.b. Figure 1 : Steel net protective element (a) fixed on the bedrock by nails and (b) located at the base of the bedrock 6