Skip to Main content Skip to Navigation
Theses

Rockfalls multi-methods detection and characterization

Abstract : Amongst mass wasting events, rockfalls remain the most unpredictable and the most frequent hazard in the alpine region. In a context of growing urbanization in mountainous regions, rockfalls represent an increasing risk for local communities and infrastructures. This thesis aims to develop an association of relevant methods for rockfall monitoring. One objective of this thesis is to associate topography measurement and seismological monitoring in order to improve significantly in understanding rockfalls dynamics. This work was mainly carried out in the Chartreuse massif (Isère, French Alps), and in particular two cliffs, Mount Saint-Eynard and Mount Granier. Using photogrammetry, we acquired diachronic Digital Elevation Models (DEMs) of the cliffs. Such monitoring enables us to carry out rockfall inventories and occurrence frequency analysis. It also provides us information on rockfall locations and their structural configurations. Combining DEMs and rockfall seismic monitoring allowed us to study relations between rockfall properties (location, volume, geometry, propagation, etc.) and the induced seismic signal. Characteristics of the seismic signal (duration and energy, frequency content, envelope shape) vary depending on the event propagation mode (mass-flow, free-fall, sliding, bouncing …). Selecting events with the same propagation type provides a more accurate characterization of rockfalls properties than when mixing different types of events. For free-falling rockfalls, we analyze the seismic signal of the detachment phases and first impacts. We found relations between seismic signals parameters and rockfalls potential energy, free-fall heights, and volumes. For mass-flow type events, we found a scaling law between rockfalls seismic energy and their volumes. By coupling DEMs and seismic records, we can reconstruct rockfall sequence with accurate timing and correct volume estimations. Controlled block releases were realized in laboratory and on-site to widen our observations on rockfall events.
Complete list of metadatas

Cited literature [192 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-02921764
Contributor : Abes Star :  Contact
Submitted on : Tuesday, August 25, 2020 - 2:53:12 PM
Last modification on : Monday, October 12, 2020 - 10:52:06 AM

File

LE_ROY_2020_diffusion.pdf
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-02921764, version 1

Collections

Citation

Gaëlle Le Roy. Rockfalls multi-methods detection and characterization. Applied geology. Université Grenoble Alpes [2020-..], 2020. English. ⟨NNT : 2020GRALU012⟩. ⟨tel-02921764⟩

Share

Metrics

Record views

103

Files downloads

49