The Vajont disaster occurred on October 9, 1963, when an extremely large landslide fell into the Erto hydroelectric reservoir and generated a wave which overtopped the Vajont dam, sweeping away the downstream village of Longarone and causing about 2000 casualties. Several experiments were carried out after the disaster to assess why previous technical estimates had underestimated the real wave height; among them a series of 2D experiments were performed at the Hydraulics laboratory of Padua University: their results, made available only recently, have been considered to perform numerical experiments with the Smoothed Particle Hydrodynamics (SPH). SPH is a well-established lagrangian mesfree particle method initially developed for astrophysical applications (Lucy, 1977; Gingold & Monaghan, 1977) and subsequently successfully extended to free-surface flows (Monaghan 1994). SPH proved to be effective even in the simulation of coupled soil-water dynamics in the rapidly varied scouring of non-cohesive sediment at the bottom of an artificial reservoir owing to a flushing manoeuvre (Manenti et al., 2012; Manenti 2011). In this work is analysed the motion of a volume of non-cohesive material (reproducing the part of Vajont landslide close to the dam) induced by a moving piston in a 2D laboratory basin. The adopted model treats the water and non-cohesive sediment as weakly compressible fluids with small density fluctuations, responding to a linear state equation; both water and sediment are divided into a set of material particles responding to the Newton’s equations of the classical physics; the i-th particles’ motion results from the numerical solution of the discretized mass and momentum conservation equations according to classic SPH approach adopting a staggered first-order explicit time integration scheme. Boundary conditions are simulated by ghost-particles: this method appears to be one of the most rigorous and can be easily implemented in a 2D geometry with straight boundary sides (Randles & Libersky, 1996). In order to keep control of ordinary numerical noises affecting the pressure field, a periodical density smoothing is carried out (Di Monaco et al., 2011). The rheological model adopted for the landslide is derived from Chambon et al. (2011) and consists in introducing a threshold t for the apparent viscosityapp above which the material behaves like a Newtonian fluid. The research, apart from the comparison of the maximum wave run-up on the mountain side with the 2D laboratory experiments, aimed at using the numerical tool to give a theoretical interpretation of the relative importance between the different physical mechanisms which concurred in generating the catastrophe.

The Vajont disaster: SPH modelling of the post-event 2D Experiments

MANENTI, SAURO;SIBILLA, STEFANO;GALLATI, MARIO;
2014-01-01

Abstract

The Vajont disaster occurred on October 9, 1963, when an extremely large landslide fell into the Erto hydroelectric reservoir and generated a wave which overtopped the Vajont dam, sweeping away the downstream village of Longarone and causing about 2000 casualties. Several experiments were carried out after the disaster to assess why previous technical estimates had underestimated the real wave height; among them a series of 2D experiments were performed at the Hydraulics laboratory of Padua University: their results, made available only recently, have been considered to perform numerical experiments with the Smoothed Particle Hydrodynamics (SPH). SPH is a well-established lagrangian mesfree particle method initially developed for astrophysical applications (Lucy, 1977; Gingold & Monaghan, 1977) and subsequently successfully extended to free-surface flows (Monaghan 1994). SPH proved to be effective even in the simulation of coupled soil-water dynamics in the rapidly varied scouring of non-cohesive sediment at the bottom of an artificial reservoir owing to a flushing manoeuvre (Manenti et al., 2012; Manenti 2011). In this work is analysed the motion of a volume of non-cohesive material (reproducing the part of Vajont landslide close to the dam) induced by a moving piston in a 2D laboratory basin. The adopted model treats the water and non-cohesive sediment as weakly compressible fluids with small density fluctuations, responding to a linear state equation; both water and sediment are divided into a set of material particles responding to the Newton’s equations of the classical physics; the i-th particles’ motion results from the numerical solution of the discretized mass and momentum conservation equations according to classic SPH approach adopting a staggered first-order explicit time integration scheme. Boundary conditions are simulated by ghost-particles: this method appears to be one of the most rigorous and can be easily implemented in a 2D geometry with straight boundary sides (Randles & Libersky, 1996). In order to keep control of ordinary numerical noises affecting the pressure field, a periodical density smoothing is carried out (Di Monaco et al., 2011). The rheological model adopted for the landslide is derived from Chambon et al. (2011) and consists in introducing a threshold t for the apparent viscosityapp above which the material behaves like a Newtonian fluid. The research, apart from the comparison of the maximum wave run-up on the mountain side with the 2D laboratory experiments, aimed at using the numerical tool to give a theoretical interpretation of the relative importance between the different physical mechanisms which concurred in generating the catastrophe.
2014
9788890456183
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11571/980248
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