Research

37 pages, 51200 KiB

Open AccessArticle

Comparing Flow-R, Rockyfor3D and RAMMS to Rockfalls from the Mel de la Niva Mountain: A Benchmarking Exercise

by François Noël, Synnøve Flugekvam Nordang, Michel Jaboyedoff, Michael Digout, Antoine Guerin, Jacques Locat and Battista Matasci

Geosciences 2023, 13(7), 200; https://doi.org/10.3390/geosciences13070200 - 30 Jun 2023

Cited by 4 | Viewed by 1936

Abstract

Rockfall simulations are often performed at various levels of detail depending on the required safety margins of rockfall-hazard-related assessments. As a pseudo benchmark, the simulation results from different models can be put side-by-side and compared with reconstructed rockfall trajectories, and mapped deposited block [...] Read more.

Rockfall simulations are often performed at various levels of detail depending on the required safety margins of rockfall-hazard-related assessments. As a pseudo benchmark, the simulation results from different models can be put side-by-side and compared with reconstructed rockfall trajectories, and mapped deposited block fragments from real events. This allows for assessing the objectivity, predictability, and sensitivity of the models. For this exercise, mapped data of past events from the Mel de la Niva site are used in this paper for a qualitative comparison with simulation results obtained from early calibration stages of the Flow-R 2.0.9, Rockyfor3D 5.2.15 and RAMMS::ROCKFALL 1.6.70 software. The large block fragments, reaching hundreds of megajoules during their fall, greatly exceed the rockfall energies of the empirical databases used for the development of most rockfall models. The comparison for this challenging site shows that the models could be improved and that combining the use of software programs with different behaviors could be a workaround in the interim. The findings also highlight the inconvenient importance of calibrating the simulations on a per-site basis from onsite observations. To complement this process, a back calculation tool is briefly described and provided. This work also emphasizes the need to better understand rockfall dynamics to help improve rebound models. Full article

(This article belongs to the Special Issue Rockfall Protection and Mitigation)

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20 pages, 30144 KiB

Open AccessArticle

Automated Delimitation of Rockfall Hazard Indication Zones Using High-Resolution Trajectory Modelling at Regional Scale

by Luuk Dorren, Christoph Schaller, Alexandra Erbach and Christine Moos

Geosciences 2023, 13(6), 182; https://doi.org/10.3390/geosciences13060182 - 16 Jun 2023

Cited by 3 | Viewed by 1015

Abstract

The aim of this study was to delimit potential rockfall propagation zones based on simulated 2 m resolution rockfall trajectories using Rockyfor3D for block volume scenarios ranging from 0.05–30 m³, with explicit inclusion of the barrier effect of standing trees, for [...] Read more.

The aim of this study was to delimit potential rockfall propagation zones based on simulated 2 m resolution rockfall trajectories using Rockyfor3D for block volume scenarios ranging from 0.05–30 m³, with explicit inclusion of the barrier effect of standing trees, for an area of approx. 7200 km² in Switzerland and Liechtenstein. For the determination of the start cells, as well as the slope surface characteristics, we used the terrain morphology derived from a 1 m resolution digital terrain model, as well as the topographic landscape model geodataset of swisstopo and information from geological maps. The forest structure was defined by individual trees with their coordinates, diameters, and tree type (coniferous or broadleaved). These were generated from detected individual trees combined with generated trees on the basis of statistical relationships between the detected trees, remote sensing-based forest structure type definitions, and stem numbers from field inventory data. From the simulated rockfall propagation zones we delimited rockfall hazard indication zones (HIZ), as called by the practitioners (because they serve as a basis for the Swiss hazard index map), on the basis of the simulated reach probability rasters. As validation, 1554 mapped past rockfall events were used. The results of the more than 89 billion simulated trajectories showed that 94% of the mapped silent witnesses could be reproduced by the simulations and at least 82% are included in the delimited HIZ. Full article

(This article belongs to the Special Issue Rockfall Protection and Mitigation)

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12 pages, 7317 KiB

Open AccessArticle

Numerical Modelling of Double-Twisted Wire Mesh for Low-Energy Rockfall Catch Fences

by Hassan Al-Budairi, Zhiwei Gao and Andrew Steel

Geosciences 2023, 13(6), 180; https://doi.org/10.3390/geosciences13060180 - 15 Jun 2023

Cited by 2 | Viewed by 1061

Abstract

Low-energy rockfall catch fences are designed to protect infrastructure such as railways and roads wherein the kinetic energy of falling rocks is less than 100 kJ. The typical design consists of a double-twisted steel wire mesh supported by ground posts and strengthened by [...] Read more.

Low-energy rockfall catch fences are designed to protect infrastructure such as railways and roads wherein the kinetic energy of falling rocks is less than 100 kJ. The typical design consists of a double-twisted steel wire mesh supported by ground posts and strengthened by anchoring wire ropes. The fence stops falling rocks by dissipating the impact energy mainly through elastoplastic stretching of steel wires in the mesh. In this study, a three-dimensional finite element model for double-twisted wire mesh was developed in Abaqus/Explicit. The model has been verified using both quasi-static loading and impact tests. It was found that proper geometrical representation is essential for accurate simulation of wire deformation modes and the interaction between double-twisted wires. The model also enables the application of the real stress–strain relationship of a single steel wire in constitutive models. Full article

(This article belongs to the Special Issue Rockfall Protection and Mitigation)

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30 pages, 4641 KiB

Open AccessArticle

Deep Neural Networks for the Estimation of Masonry Structures Failures under Rockfalls

by Olga Mavrouli, Athanasia D. Skentou, Josep Maria Carbonell, Markos Z. Tsoukalas, M. Amparo Núñez-Andrés and Panagiotis G. Asteris

Geosciences 2023, 13(6), 156; https://doi.org/10.3390/geosciences13060156 - 24 May 2023

Viewed by 1276

Abstract

Although the principal aim of the rockfall management is to prevent rock boulders from reaching the buildings instead of the buildings resisting the boulder impacts, there usually exists a residual risk that has to be assessed, even when structural protection measurements are taken. [...] Read more.

Although the principal aim of the rockfall management is to prevent rock boulders from reaching the buildings instead of the buildings resisting the boulder impacts, there usually exists a residual risk that has to be assessed, even when structural protection measurements are taken. The evaluation of the expected damage of buildings due to rockfalls using empirical data from past events is not always possible, as transferring and applying damage observations from one area to another can be unrealistic. In order to simulate potential rockfall scenarios and their damage on buildings, numerical methods can be an alternative. However due to their increased requirements in expertise and computational costs, their integration into the risk analysis is limited, and simpler tools to assess the rockfall vulnerability of buildings are needed. This paper focuses on the application of artificial intelligence AI methods for providing the expected damage of masonry walls which are subjected to rockfall impacts. First, a damage database with 672 datasets was created numerically using the particle finite element method and the finite element method. The input variables are the rock volume (VR), the rock velocity (RV), the masonry wall (t) and the masonry tensile strength

f_{m}

. The output variable is a damage index (DI) equal to the percentage of the damaged wall area. Different AI algorithms were investigated and the ANN LM 4-21-1 model was selected to optimally assess the expected wall damage. The optimum model is provided here (a) as an analytical equation and (b) in the form of contour graphs, mapping the DI value. Known the VR and the RV, the DI can be directly used as an input for the vulnerability of masonry walls into the quantitative rockfall risk assessment equation. Full article

(This article belongs to the Special Issue Rockfall Protection and Mitigation)

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17 pages, 8321 KiB

Open AccessArticle

Towards a Hybrid Design Approach of Anchored Drapery Systems

by Maddalena Marchelli, Antonio Pol, Daniele Peila and Fabio Gabrieli

Geosciences 2023, 13(5), 147; https://doi.org/10.3390/geosciences13050147 - 14 May 2023

Viewed by 1181

Abstract

Anchored drapery meshes represent a worldwide adopted protective solution against rockfall. The mechanical performance of a wire mesh is evaluated through laboratory procedures in which the boundary conditions strongly differ from the ones typical of field applications. This shows that the laboratory characterization [...] Read more.

Anchored drapery meshes represent a worldwide adopted protective solution against rockfall. The mechanical performance of a wire mesh is evaluated through laboratory procedures in which the boundary conditions strongly differ from the ones typical of field applications. This shows that the laboratory characterization is, in general, not representative of the field behavior. In this work, referring to a double-twisted wire mesh, a simple approach allowing the extension of the laboratory characteristic values to field conditions is proposed. The approach is based on the definition of analytical relations for evaluating the effects of both the mesh’s system geometry and the loading condition on the force–displacement response. These relations are derived from previously calibrated laboratory tests and are extended to different configurations on the basis of a large number of discrete element simulations. A master curve allowing the prediction of the entire force–displacement response of a general configuration of the drapery system is then defined. The results of this study can provide useful information for designing anchored drapery systems and can be easily associated with standard limit equilibrium calculations to move toward a hybrid design approach that couples forces with mesh deformations. Full article

(This article belongs to the Special Issue Rockfall Protection and Mitigation)

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17 pages, 13950 KiB

Open AccessArticle

Steel Baffles as a Rockfall Protection Measure for Mountainous Urban Settings

by Jude Shalitha Perera and Nelson Lam

Geosciences 2023, 13(3), 93; https://doi.org/10.3390/geosciences13030093 - 22 Mar 2023

Viewed by 1392

Abstract

A form of steel baffles, which is made of steel poles encased in concrete and embedded into the ground, are introduced in this article. This type of protective installation is to be located on previously identified/designed catchment at multiple levels up the hillslope [...] Read more.

A form of steel baffles, which is made of steel poles encased in concrete and embedded into the ground, are introduced in this article. This type of protective installation is to be located on previously identified/designed catchment at multiple levels up the hillslope to fence off large fallen boulders during landslides or rockfalls. These baffles are intended to serve as added-on protection to filter barriers (array of baffles) that have recently gained popularity as a means of filtering out coarse debris. The aforementioned protective devices are to be installed in strategic positions close to unstable rocks (noting that the velocity of impact can be much reduced at the upstream end of the rockfall trajectory). The proposed design involves only a simple hollow steel section, which is embedded into the ground. The installation process involves manually excavating a hole in the ground to accommodate the baffle, followed by backfilling with concrete. A straightforward calculation method, which is found on the established principles of structural dynamics and soil mechanics, has been developed to determine the section sizes and embedment depths for a given impact scenario. Based on the presented design procedure, a set of design charts have been developed for expediting the design and analysis process. The presented calculation methodology based on use of design charts have been validated by comparison with data generated by LS-DYNA simulations. Full article

(This article belongs to the Special Issue Rockfall Protection and Mitigation)

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20 pages, 95804 KiB

Open AccessArticle

A Quick QGIS-Based Procedure to Preliminarily Define Time-Independent Rockfall Risk: The Case Study of Sorba Valley, Italy

by Giulia Torsello, Gianmarco Vallero, Lorenzo Milan, Monica Barbero and Marta Castelli

Geosciences 2022, 12(8), 305; https://doi.org/10.3390/geosciences12080305 - 10 Aug 2022

Cited by 4 | Viewed by 2270

Abstract

Rockfalls are widespread, rapid, and high-energy landslide phenomena that could potentially affect large portions of populated lands. The preliminary identification of the most rockfall-prone zones is a challenging task, especially in times of extreme and unpredictable climate change. Even slight environmental modifications can [...] Read more.

Rockfalls are widespread, rapid, and high-energy landslide phenomena that could potentially affect large portions of populated lands. The preliminary identification of the most rockfall-prone zones is a challenging task, especially in times of extreme and unpredictable climate change. Even slight environmental modifications can produce significant consequences in terms of exposure, hazard, and risk. Therefore, a timely risk assessment is paramount for territorial administrators to plan and prioritize adequate countermeasures. Risk assessment is crucial to guaranteeing the safety of human lives, the integrity of structures and infrastructures, the preservation of historic and environmental heritage, and the safeguard of economic activities. Hence, new and rapid evaluation methods for rockfall hazard, vulnerability, and risk are needed to identify the most critical areas where more indepth analyses aimed at the design of protective works should be carried out. This study proposes a quick, innovative, and completely GIS-based procedure to preliminarily assess rockfall time-independent hazard and risk in large areas. Propagation analysis is performed by integrating powerful QGIS plugin QPROTO, which can estimate rockfall energy within the invasion area in a simplified way, with the slope units polygons of the Italian territory for the definition of the input parameters. The quantification of risk was obtained by the application of the multidisciplinary IMIRILAND methodology, again within a free and open QGIS environment. Lastly, to test the capabilities of the method, the procedure was applied to a case study of the Sorba Valley (Piemonte, Italy), a tourist region in the northwestern Italian Alps. The findings offer an important contribution to the field of land-planning activities and risk-management strategies. Full article

(This article belongs to the Special Issue Rockfall Protection and Mitigation)

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25 pages, 9638 KiB

Open AccessArticle

Sensitivity Analysis of the Global Response of Flexible Rockfall Barriers

by Cyril Douthe, Chloé Girardon and Romain Boulaud

Geosciences 2022, 12(2), 75; https://doi.org/10.3390/geosciences12020075 - 06 Feb 2022

Cited by 4 | Viewed by 1904

Abstract

Protection barriers against the fall of boulders and rocks are structures with non-linear mechanical behaviour that make the study particularly complex. In this study, the understanding of an experimentally observed variability was investigated numerically using a non-linear spring-mass equivalence. First, key figures of [...] Read more.

Protection barriers against the fall of boulders and rocks are structures with non-linear mechanical behaviour that make the study particularly complex. In this study, the understanding of an experimentally observed variability was investigated numerically using a non-linear spring-mass equivalence. First, key figures of the experiments on which this study is based are detailed. Then, the numerical model for the dynamic simulation of the barrier deformation under impact is presented. Finally, the variability due to block-related parameters and then net-related parameters are explored and evidence the role of the cables’ geometric stiffness in the global response of the fence. Full article

(This article belongs to the Special Issue Rockfall Protection and Mitigation)

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