Scenari di rischio dell'interazione tra spostamenti indotti da fenomeni franosi e rete viaria

Earthquake-triggered landslides (EQtL) are worldwide known to induce severe damage to buildings and historical and cultural heritage as well as cause human losses. Moreover, EQtL have a not negligible impact on road networks since they are responsible for obstructions and consequent service interruption. This effect compromises the strategic functions of the road network also in the management of the emergency, thus representing a critical feature for the design of Emergency Limit Conditions (CLE). An analysis of scenario of EQtL involving road network is here presented for the municipality of Accumoli through a probabilistic way specifically implemented after the already consolidate PARSIFAL approach (Probabilistic Approach to pRovide Scenarios of earthquake–Induced slope FAiLures; Esposito et al., 2016; Martino et al., 2018; 2019b). More in particular, the here proposed application of PARSIFAL is focused on providing a probabilistic scenario of slope failures involving the road cuts and the roadway itself. This approach includes three steps: 1) susceptibility analysis of slope failures; 2) slope stability analysis; 3) mapping of results. The first step include a kinematic compatibility analysis for rock failures and a susceptibility analysis for shallow landslides. The slope stability phase combines a pseudostatic and a pseudodynamic analysis as it firstly define an horizontal critical acceleration for each failure mechanism and following compute a distribution of coseismic displacements to evaluate the probability of exceedance of an assumed critical threshold (P (D>Dy)). If no coseismic displacements result from computation, a safety factor (FS) is calculated under pseudostatic conditions. In the third step a comprehensive mapping of the results is obtained where territorial units prone to failures are identified through predefined chromatic codes. The validation of the PARSIFAL tool specifically designed for road cuts and fills was carried out by checking the mapped results with the spatial distribution of the EQtL inventoried in the CEDIT catalogue (www.ceri.uniroma1.it/index_cedit.html) after the Amatrice earthquake on 24 August 2016. These outputs can be regarded as a reliable tool for the road vulnerability analysis, so supporting maintenance plans along the road network and providing elements for Limit Emergency Condition management.