PRIN PNRR 2022 - Improving the modeling capabilities of geophysical granular flows through experimental and numerical simulations

The Project is aimed at improving our knowledge and modeling capabilities of natural granular flows like landlides, volcanic block and ash flows and pyroclastic density currents by integrating large-scale flow experiments using an existing state of the art facility and numerical modeling of the experiments. In particular, we will focus on the interaction between the flow and the substrate from the particle scale up to the bulk flow scale and how this interaction affects the flow characteristics and related hazard. These include flow velocity, thickness and internal structure, which are all factors contributing to the dynamic impact that these flows can have on the territory, human beings and infrastructures. As such, the proposed research will serve as a pillar to improve our understanding of the mobility of these flows and consequently our ability to simulate the areas most likely to be inundated in geological settings where these flows occur and their impact. Therefore, our proposal is embedded into the wider area of natural disaster risk reduction, to which we contribute by acting on the hazard quantification component.

The two research units will work together on the fulfillment of the following objectives:

1. quantify the interplay between the granular material properties (e.g. particle size distribution) and substrate roughness and the resulting effect on both the bulk flow properties (thickness, flow-front speed, internal fabric) and the granular flow properties near the substrate;

2. verify the generation of pore pressure, which is an important factor favoring the lubrication between the flow and the substrate, hence enhancing the flow mobility, in situations in which the granular material is not initially fluidised before it starts moving.

Furthermore, we will quantitatively relate this important parameter to the wall and granular material properties, e.g., wall roughness, particle size distribution, flow thickness. To our knowledge, it is the first time that pore pressure generation in initially not-fluidized flows is investigated at a large scale, using natural material of varying size and density and with an attempt to find a quantitative relationship between the pore pressure and the substrate and particle properties.

3. Validate and improve both complex numerical models working at the particle-wall scale and models designed to simulate the bulk flow scale that are routinely used for hazard applications.

The team, characterized by a high degree of multidisciplinarity and diverse expertise, will also dedicate significant resources to ensure dissemination and outreach and guarantee the impact of the expected findings.