Numerical simulation of propagating landslides

The triggering of a landslide can be induced by natural causes (erosion, heavy rainfall, and earthquake) or by human actions (excavation, construction, and mining). The propagation velocity is affected by the slope conformation, the material, and the failure mechanism. Landslides characterized by high velocities and long runout distances behave in a fluid-like manner. Modeling such fluidized material is important for the creation of maps of hazardous areas, to estimate the entity of the hazard and finally to design appropriate protective measures.

A landslide is here intended as a gravity-driven free surface flow (granular flow, mud flow, debris flow, etc.). The numerical analysis of this type of problems requires the ability to track free surfaces and interfaces. A Lagrangian approach with continuous remeshing, to account for the extremely large deformations and consequent mesh distortion, based on the particle finite-element method (PFEM) is here adopted.

SIMULATION OF VAJONT DISASTER

The landslide impulse wave event of Vajont (northern Italy) was the one with the highest number of associated casualties (around 2000). On the night of October 9th 1963, about 275 million cubic meters of rock detached from the northern side of the Mount Toc, slumped on the water basin and produced a massive water runup of around 200m on the opposite flank of the valley. A significant part of the huge impounded water volume overtopped the dam and, after traveling about 1.5km through the Vajont gorge, reached the Piave valley destroying almost entirely the village of Longarone.

A fully-resolved three-dimensional model of the Vajont valley is presented. The numerical results are compared to the post-event observations in terms of landslide velocity and runout, geometry of the deposit, maximum water runup, dam overtopping wave, and water discharge in the downstream valley showing a good agreement with observations and reconstructions.

The work is carried out in collaboration with CIMNE (International Centre for Numerical Methods in Engineering) , Universitat Politècnica de Catalunya (UPC) and Università degli Studi di Milano Bicocca (UNIMIB)

People involved: M. Cremonesi (POLIMI), U. Perego (POLIMI), A. Franci (CIMNE and UPC), E. Oñate (CIMNE and UPC), G. Crosta (UNIMIB)

Franci A., Cremonesi M., Perego U., Crosta G., Oñate E. (2020) 3D Simulation of Vajont Disaster. Part 1: Numerical Formulation and Validation, Engineering Geology, vol. 279, pp.105854, DOI:10.1016/j.enggeo.2020.105854

Franci A., Cremonesi M., Perego U., Oñate E., Crosta G. (2020) 3D Simulation of Vajont Disaster. Part 2: Multi-Failure Scenarios,  Engineering Geology, vol. 279, pp. 105856, DOI:10.1016/j.enggeo.2020.105856