H2020Индивидуална стипендия2020–2022

kelbus2 · Experimental and numerical study of long runout landslides

„Хоризонт 2020“ — Действия „Мария Склодовска-Кюри“

Период: 2020-01-15 → 2022-04-14
Финансиране от ЕС: 196 708 €
Участници: 1
Схема: MSCA-IF-EF-ST

Линиите свързват координатора с партньорите.

Накратко на български

Разстоянието, което изминават свланите и снежните лавини, се анализира чрез лабораторни опити с гранулирани материали. Това помага за по-точното предвиждане на обхвата на тези опасни явления, като се вземе предвид размерът на частиците в потока.

Този кратък обзор е генериран от изкуствен интелект

Кратко обяснение, генерирано от езиков модел по текста на CORDIS. Оригиналът е по-долу.

Резултати накратко

Experimental and numerical study of long runout landslides

A main objective in landslide research is to predict how far they will travel, as every year they claim thousands of lives and leave behind lasting ecological hazards. Landslides are complex, and a complete understanding of landslides in principle requires accounting for all of these parameters. A systematic study of each one is difficult if not impossible for natural landslides, and the vast variety of parameters has even led to landslides and avalanches with very different material and parameter values to be treated as distinct systems, even if the basic geometry and physics appears to be similar. The result of both the experimental and parallel numerical study was that a relevant parameter absent in prevalent theories of landslide runout was the landslide grain size. We made a radical improvement on our ability to predict landslide runout by using systematic laboratory experiments of granular flow with a simplified landslide geometry combined with a scaling analysis. We found that additionally accounting for the granular nature of the flow through the constituent grain size, and correctly accounting for the fall height, reveals a striking correlation of normalized runout with landslide size which when combined with field data extends to nearly ten orders of magnitude in size. We thus united seemingly disparate fields such as small-scale laboratory granular experiments, landslides, and snow avalanches, and dramatically enhanced runout prediction for dense flows. Our work thus alleviates the need for special theories and removes some of the mystery clouding the discussion of these fascinating, if extremely dangerous, phenomena. In addition, we also determined the minimum landslide size required to observe this scaling, which we find is set by a combination of air drag, grain size, and fall height. The scaling of this minimum size was determined with the assumption that for small total volumes, landslides behave as a granular gas, while at large volumes they behave as a dense granular liquid. This result will help to guide the design of any future laboratory experiments aimed at understanding natural landslide behavior.

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз

Цел на проекта

Landslides, the violent motion of large masses of debris, rock or snow, are an ever-present danger in mountainous regions the world over. After the landslide material falls down the mountainside, it will run out some distance away from the mountain even on relatively flat surfaces until the energy it gained from falling is dissipated by friction with the terrain. Although a simple energy balance argument suggests that a single rock cannot travel farther than the height from which it fell, many landslide runouts extend their ruin to seemingly safe distances far removed from their origin. These long runout landslides have baffled scientists for over a century, ever since Albert Heim recorded his study of the Elm rock landslide that devastated the village of Elm, Switzerland in 1881. There are many explanations for this phenomenon, such as lubrication by an interstitial fluid, but none of these satisfactorily addresses how a completely dry landslide can run out so far. Not understanding how and when long runouts will occur makes hazard mitigation and prediction extremely difficult, highlighting the urgency of this issue. Recently, Melosh and coworkers have provided support for a mechanism borrowed from the fluidization of impact craters, “acoustic fluidization”, by using idealized 2D simulations of circular disks, but more work is needed to show that this mechanism is a feature of real 3D flows and robust for a range of conditions. We will perform laboratory experiments and fully 3D simulations of granular flows using simultaneous pressure and velocity measurements to test the acoustic fluidization hypothesis. We will also look for a crossover between this dry mechanism and the lubrication mechanisms for wet landslides. Besides application to landslide engineering, we will also explore for the first time how fundamental features of granular flows such as shear flow instabilities (clustering and longitudinal stripes) affect the rheology of landslides and long runouts.

Оригинален текст от CORDIS (на английски).

Участници

UNIVERSITE DE BORDEAUX · BordeauxКоординаторФранция