3D simulation of Vajont disaster. Part 2: Multi-failure scenarios

Abstract

Prediction of multi-hazard events requires an informed and judicious choice of the possible scenarios. An incorrect definition of landslide conditions in terms of expected failure volume, material behavior, or boundary conditions can lead to inaccurate predictions and, in turn, to wrong engineering and risk management decisions. Reduced-scale experiments carried out two years before the Vajont disaster were carried out with a material not representative of the actual rockslide behavior and failed in not considering the simultaneous failure of the whole landslide body. Based on these inappropriate assumptions, the physical models led to wrong estimates of the safety operational level for the Vajont reservoir. This work uses the Particle Finite Element Method (PFEM) to analyze the implications of the wrong hypotheses considered in the pre-event experiments, simulating numerically the Vajont disaster for different sliding volumes and material properties. The use of the PFEM for the accurate assessment of the consequences of landslides impinging in water reservoirs has been already validated in a companion paper. In this work, we demonstrate the capabilities of a robust and reliable numerical modeling approach for the simulation of different scenarios assessing what could have been a safe operational reservoir level in the case of a landslide generated impulse wave. The three-dimensional analyses were run with a high mesh resolution and demonstrate the suitability and robustness of the PFEM model for large-scale landslide and multi-hazard events simulation.

3D simulation of Vajont disaster. Part 1: Numerical formulation and validation

“…18 is also helpful to perceive the crucial effect on the tsunami wave given by the push of the easternmost part of the rockslide (Figs. 18a-18b), as it is confirmed by the analyses of the companion paper (Franci et al, 2020) analyzing the solely collapse of the eastern lobe of the rockslide.…”

“…In this work, the Vajont case study is analyzed with the PFEM using a 3D fully-resolved model and, at the best of our knowledge, with the highest mesh resolution ever published. In a companion paper (Franci et al, 2020), hypothetical scenarios of the Vajont disaster are analyzed and related to the pre-event experimental predictions of Ghetti (1962).…”

Towards a predictive multi-phase model for alpine mass movements and process cascades

“…In Fig. 2c, we compare the discharge hydrograph from our study with the ones obtained by Vacondio et al (75) and Franci et al (22). The total value of the flooded water (i.e.…”

A Lagrangian-Eulerian procedure for the coupled solution of the Navier-Stokes and shallow water equations for landslide-generated waves

“…First applications of this holistic strategy can be found in [24] and [25], where shallow water models were used for both the landslide and the water body. Only recently, more accurate 3D monolithic approaches for LGW problems have been presented, see for example [26][27][28][29][30]. Nevertheless, the computational cost of this fully resolved method can be still unaffordable for large-scale events.…”

“…Several previous works have shown the accuracy of the PFEM to model landslides [38][39][40], also in cascading events [41][42][43][44]. In this work, we use the PFEM approach that has been successfully applied to LGW scenarios in [45] and in [28,29], where 3D simulations of the Vajont disaster were presented. This work aims at being a proof of concept of this new coupled strategy for real LGW scenarios.…”