287 results on '"Bourrier, Franck"'
Search Results
102. Un nouveau modèle pour optimiser la mise en place d'une ligne de câble et améliorer la planification des opération de débardage par câble
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Dupire, S., Bourrier, Franck, Berger, F., Ecosystèmes montagnards (UR EMGR), and Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)
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[SDE]Environmental Sciences - Abstract
International audience; The use of cable yarding systems constitutes an interesting solution for steep-slope harvesting in mountain forests. However, it requires many specific skills for both forest managers and operators. The purpose of this study is to provide a numerical tool to help managers in planning cable yarding projects and to facilitate the set-up of a cable line by operators. A model was developed and coded in Python language which allows fast calculation of the load path and tensile forces along the cable for different 3D configurations. This model uses theoretical equations initially developed for the mechanical design of cable structures. Its applicability in forestry was validated by field experiments. An additional module using a high-resolution digital terrain model optimizes the cable layout and automatically places required intermediate supports. If geographic information about timber volume is available, it also allows combining technical possibility with harvesting potential. From the managerial point of view, this tool presents significant advantages for forest operations planning. Moreover, operators’ productivity can be improved with the technical outputs of this model, which help to shorten the time spent in setting up a cable line and thereby reduce the total cost of a cable project.
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- 2014
103. Rockfall impacts on trees and wooden structures
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Bourrier, Franck, Bertrand, D., Olmedo-Manich, I., Toe, D., Berger, F., Limam, A., Ecosystèmes montagnards (UR EMGR), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Laboratoire de Génie Civil et d'Ingénierie Environnementale (LGCIE), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)
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[SDE]Environmental Sciences - Abstract
International audience; Présentation réalisée lors du 1st Yade Workshop.
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- 2014
104. Felled trees as rockfall protection devices: experimental study for numerical model calibration
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Olmedo, I., Bourrier, Franck, Bertrand, D., Berger, F., Limam, A., Ecosystèmes montagnards (UR EMGR), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Laboratoire de Génie Civil et d'Ingénierie Environnementale (LGCIE), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)
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[SDE]Environmental Sciences - Abstract
International audience; Forest is a well known and efficient natural protection solution against rockfall. In forested areas, the maintenance of forests is required to ensure their protective function and health. During this process that consists in removing some trees, the protective capacity of the forest decreases. To compensate the temporary loss of protection, some of the felled trees can be left in an oblique position to the slope. It is a financially feasible solution to ensure the protection against rockfall during the regeneration of forests. Thus, felled trees can become a useful protection system if they are correctly placed. No studies have been done concerning the efficiency of these devices and particularly their resistance to rock impacts and their energy dissipation capacity. In order to estimate the capacity of these devices to dissipate energy, it is necessary to study the dynamic response of tree stems under impact as well as rock's trajectory changes due the interaction with such structures. Experimental and numerical studies are carried out to determine the efficacy of this devices. Laboratory experiments enabled studying the response of fresh wood stems under dynamic and quasi-static loadings. A Mouton-Charpy pendulum was used on the dynamic loading tests performed onto simply supported stems. The experimental device was instrumented in order to obtain the impact force data and the stem's displacements fields. The mechanical properties of fresh wood are analyzed from the experimental results which also allow carrying out a detailed study of the stems dynamic response. A numerical model based on the Discrete Element Method (DEM) enables to simulate the interaction of a rock and a felled tree device. To simulate the rock - tree interactions, rocks are represented by spherical solid bodies while cylindrical bodies represent the trees. The fresh wood constitutive law and the contact law are integrated on the model allowing realistic simulations. The numerical model is calibrated and validated by the experimental data. The estimation of the protective capacity of these devices is assessed by the integration of the DEM model on a rockfall trajectographic one.
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- 2014
105. Modélisation probabiliste du rebond d'un bloc sur un sol dans le contexte de l'analyse de la trajectographie des chutes de blocs
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Bourrier, Franck, Eckert, Nicolas, Berger, F., Nicot, François, Darve, F., Ecosystèmes montagnards (UR EMGR), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Erosion torrentielle neige et avalanches (UR ETGR (ETNA)), Laboratoire sols, solides, structures - risques [Grenoble] (3SR), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Université Joseph Fourier - Grenoble 1 (UJF)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)
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[SDE]Environmental Sciences ,ROCKYFOR3D - Abstract
National audience; Ce travail de recherche est dédié à l'amélioration des modèles de rebond d'un bloc rocheux sur un sol naturel classiquement utilisés en analyse trajectographique. L'objectif final est de développer un modèle probabiliste de rebond d'un bloc sur un sol. Un modèle numérique, basé sur la méthode des éléments discrets, de l'impact d’un bloc sur un sol grossier a été développé et utilisé pour réaliser une campagne extensive de simulations numériques. L'analyse statistique, par une approche bayésienne hiérarchique, des résultats obtenus suite à cette campagne a permis de définir un modèle probabiliste de rebond reliant les vitesses de l'impactant après impact aux vitesses avant impact. Ce modèle est capable de quantifier la variabilité des vitesses après impact dans des cas de figure très variés. Une procédure d'intégration du modèle probabiliste de rebond dans le logiciel d'analyse trajectographique Rockyfor3D a été développée. La pertinence de cette démarche est étayée par la bonne adéquation entre les résultats d'essais en grandeur réelle menés à Irstea Grenoble et les prédictions d'une analyse trajectographique du site d'essais utilisant cette procédure.
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- 2014
106. Estimation of rockfall frequency from simulated trajectories and observed tree impacts
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Monnet, J.M., Bourrier, Franck, Lopez-Saez, J., Corona, C., IRSTEA GRENOBLE UR EMGR FRA, CNRS UMR 6042 GEOLAB CLERMONT FERRAND FRA, Ecosystèmes montagnards (UR EMGR), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Laboratoire de Géographie Physique et Environnementale (GEOLAB), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Université Clermont Auvergne (UCA)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Centre National de la Recherche Scientifique (CNRS), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut Sciences de l'Homme et de la Société (IR SHS UNILIM), and Université de Limoges (UNILIM)-Université de Limoges (UNILIM)-Université Clermont Auvergne [2017-2020] (UCA [2017-2020])-Centre National de la Recherche Scientifique (CNRS)-Université Clermont Auvergne (UCA)
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CHUTE DE PIERRES ,FREQUENCE ,TRAJECTOGRAPHY ,SIMULATION NUMERIQUE ,DENDROMETRIE ,[SDE]Environmental Sciences ,TRAJECTOGRAPHIE ,SERIE CHRONOLOGIQUE ,NUMERICAL SIMULATION ,FOREST MENSURATION ,ROCKFALL - Abstract
[Departement_IRSTEA]Territoires [TR1_IRSTEA]SEDYVIN; International audience; While significant progress has been achieved regarding the modeling of rockfall propagation, including the interaction with forest cover, the estimation of the spatial distribution of rockfall frequency in release areas remains a challenging task. Indeed, the very low number of observed events makes any statistical modeling difficult, so that estimations are generally based on expert knowledge regarding the rock structure of start zone and a few recorded events. Meanwhile, recent dendrochronological studies have shown that trees, as silent witnesses of numerous events, bring information about the spatial distribution of rockfall trajectories. This data can be compared to simulated trajectories in order to reconstruct the most probable start zones. This study presents a methodological framework for the resolution of this problem and a real-case example. Consider a forest patch f located below a cliff with Ns potential rockfall start points. The expected value of the number of impacts in this forest patch during lapse T can be calculated as (1) : Impacts(f)=T*SUM(Pstart(i)*Ppropagation(i,f)) with Pstart(i) the probability of rockfall for the start point I, Ppropagation(i,f) the probability that a rockfall from start point i impacts at least one tree in the forest patch f . The matrix formulation for the whole forest divided in Nf forest patches is (2): Impact=T*Pstart*Propagation. Ppropagation can be estimated with numerical simulations, by taking into account the current state of the forest stand if trees are measured and georeferenced, and if the volume of rockfall is known. Impact can be also be observed on the field. Under the assumption that the forest stand and the start frequencies do not change during lapse T, the equation system (2) can be solved for the coefficients of Pstart. This framework was tested on a rockfall area located in Valdrôme, France, where more than 1000 trees were measured and geolocated in a one hectare stand located below a cliff with rockfall activity. The number of impacts on each tree was observed and starting points were determined based on a slope criterion applied to a digital terrain model. The rockfall trajectories were simulated with the RockyFor3D software. The system (2) was solved with an optimization routine. Results show that the rockfall frequencies display high spatial variability and that 21% of starting points account for more than 50% of rockfall releases. The coefficients of Pstart can then be used to weight the simulated trajectories in order to map the spatial variability of rockfall trajectories and corresponding kinetic energies, which is an important step for a better identification of hazard areas. The proposed framework can thus lead to a numerical solution, but it relies on numerous assumptions. The spatial variations of rockfall volume are not taken into account and the forest stand is supposed time-invariant. This last point could be tackled by simulating trajectories during past stages of the stand evolution with growth simulation models.
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- 2014
107. Studies of wood decay and its mechanical consequences for wood used in structures of ecological engineering
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Barré, J.B., Bourrier, Franck, Ecosystèmes montagnards (UR EMGR), and Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)
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[SDE]Environmental Sciences ,technology, industry, and agriculture ,complex mixtures - Abstract
International audience; This study concerns biological degradation of non-treated wood used in ecological engineering structures. The structural design requires knowing the mechanical properties of the wood parts composing the structures at the building time as well as their evolution due to wood degradation. A bibliographic review showed a lack of scientific knowledge on these aspects, especially for wood degraded by an entire fungi community as observed in natural conditions.
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- 2013
108. Suitability of airborne laser scanning for the assessment of forest protection effect against rockfall
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Monnet, Jean-Matthieu, primary, Bourrier, Franck, additional, Dupire, Sylvain, additional, and Berger, Frederic, additional
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- 2016
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109. Impacts of land-use and land-cover changes on rockfall propagation: Insights from the Grenoble conurbation
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Lopez-Saez, Jérôme, primary, Corona, Christophe, additional, Eckert, Nicolas, additional, Stoffel, Markus, additional, Bourrier, Franck, additional, and Berger, Frédéric, additional
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- 2016
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110. Accounting for the variability of rock detachment conditions in designing rockfall protection structures
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Bourrier, Franck, primary, Baroth, Julien, additional, and Lambert, Stéphane, additional
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- 2015
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111. Les arbres abattus en tant que système de protection contre les chutes de pierres : impact sur tiges de bois vert simplement appuyées, étude expérimentale et numérique
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Olmedo, I., Bourrier, Franck, Bertrand, D., Berger, F., Limam, A., Ecosystèmes montagnards (UR EMGR), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Laboratoire de Génie Civil et d'Ingénierie Environnementale (LGCIE), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)
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[SDE]Environmental Sciences - Abstract
International audience; In this paper, experimental and numerical studies carried out to determine the efficacy of felled trees made structure are presented. In this research work, felled trees are simplified and represented by simply supported fresh wood stems. The aim of this study is to analyze the impact of a projectile on those stems. The energy transfers between the projectile and the stem during an impact and the dynamic response of the stems are the two main subjects of this study.
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- 2013
112. Exploring the root-soil interaction mechanisms using discrete simulations of rooted soils
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Bourrier, Franck, Kneib, F., Chareyre, B., Fourcaud, Thierry, Irstea Publications, Migration, Ecosystèmes montagnards (UR EMGR), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Erosion torrentielle neige et avalanches (UR ETGR (ETNA)), Laboratoire sols, solides, structures - risques [Grenoble] (3SR), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Université Joseph Fourier - Grenoble 1 (UJF)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS), Botanique et Modélisation de l'Architecture des Plantes et des Végétations (UMR AMAP), and Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut de Recherche pour le Développement (IRD [France-Sud])
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[SDE] Environmental Sciences ,[SDE]Environmental Sciences - Abstract
International audience; Using plant roots for soil mechanical reinforcement is a common practice in the field of ecological engineering to improve slopes and river banks stability. The study of the influence of roots on the stability of forested slopes requires identifying the effect of the different root-soil interaction processes depending on soil and roots properties. For that purpose, a numerical model of rooted soils based on the Discrete Element Method was developed. The model was used to study the interaction between the roots and the soil for different loading cases and, in particular, for direct shear tests. The soil is modelled as an assembly of locally interacting spheres and the roots are modelled as deformable cylinders in the soil matrix. The model allows accounting for the root tensile loading until breakage, the root bending loading, the root-soil cohesive interaction until cohesion breakage, the root slippage associated with a frictional resistance at the root-soil interface. The study focuses on identifying the different root-soil interaction mechanisms depending on the soil type. Both frictional and cohesive soil types were used in the simulations. The effects of the roots mechanical properties - tensile, bending modulus and root-soil interfacial friction angle - and of the root number were also analyzed for the different soil types. The analysis was held both at the macroscopic scale, that is on the shear stress-strain relationships for direct shear test, and at the particles scale by analysing the spatial distribution of the contact forces magnitude, sliding contacts, and adhesion breakage for cohesive soils. The effect of the roots strongly depends on the shear strain for any soil type. The roots do not provide reinforcement but entail decrease in the shear resistance until the shear strain is large enough to induce a significant loading of the roots. For frictional soils and increasing shear strain values, the processes inducing the increase in the soil shear resistance are successively the pure tensile loading of the roots and the tensile loading combined with slippage of the root-soil interface. For cohesive soils, the pure tensile loading of the roots is followed by a progressive breakage of the cohesive root-soil links and by a complete slippage of the roots. The results show that the influence of the root number is significant if the prevailing processes are root tensile loading combined with slippage whereas it is less important if root loading is combined with progressive breakage of the cohesive links for the root configurations explored. These results illustrate the interest of the model developed to analyze the stability of rooted soils.
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- 2013
113. Utilisation de modèles de type analyse trajectographique et écoulement granulaire pour la prédiction de la propagation de blocs rocheux
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Bourrier, Franck, Dorren, L., Hungr, O., Ecosystèmes montagnards (UR EMGR), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), FOEN BERN CHE, Partenaires IRSTEA, Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), and UNIVERSITY OF BRITISH COLUMBIA VANCOUVER CAN
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GRANULAR FLOW ,[SDE]Environmental Sciences ,MODELLING ,FAHRBOESCHUNG ,ENERGY LINE ,FRAGMENTAL ROCKFALL - Abstract
International audience; The term rockfall is often used ambiguously to describe various mass movement processes. Here we propose more precise terminology based on the physical nature of the moving mass, differentiating between two distinct types of rockfall: fragmental rockfall and rock mass fall. For both rockfall types, the current knowledge of the mechanisms controlling propagation of the mass movement are described, showing how these mechanisms can be simulated with different modelling approaches. However, we point out that almost no development has been realized concerning dynamic behaviour of the transitional processes between these two end-member rockfall types. Some simplified means of dealing with these complications are suggested, but we emphasize that a considerable amount of fundamental methodological development remains necessary.
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- 2013
114. Predicting mechanical degradation indicators of silver fir wooden strips using near infrared spectroscopy.
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Barré, Jean, Bourrier, Franck, Cécillon, Lauric, Brancheriau, Loïc, Bertrand, David, Thévenon, Marie, and Rey, Freddy
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The management of ecological engineering structures making up a timber structure requires periodical evaluations, including the level of decay of the constituent parts of the timber structure. Methods exist to measure the level of decay in the laboratory or in the field. However, they are rarely suitable for the conditions of ecological engineering structures, or give partial information. The aim of this study was to predict two mechanical degradation indicators ( $$Dw_{MOE}$$ and $$Dw_{MOR}$$ ) of silver fir ( Abies alba) wooden strips during microbial decomposition using near-infrared spectroscopy (NIRS). For 1.5 years, the degradation of 180 squared wooden strips, 30 mm wide and 500 mm long, buried in a greenhouse near Grenoble, France (Altitude: 200 m) was monitored. $$Dw_{MOE}$$ and $$Dw_{MOR}$$ were set from the normalized losses in modulus of elasticity (MOE) and modulus of rupture (MOR), two mechanical properties classically used for timber-structure design. A calibration set of 109 samples was selected to build two separate predictive models of $$Dw_{MOE}$$ and $$Dw_{MOR}$$ using partial least square regression. The NIR-based models applied to a validation set of 47 samples indicated good prediction performance. The model has a root mean square error of prediction (RMSEP) of 0.15 and a coefficient of determination ( $$r^2_p$$ ) of 0.79. The $$Dw_{MOR}$$ model has a RMSEP of 0.13 and a $$r^{2}$$ -value of 0.91. These results highlight the considerable potential of NIRS in assessing the extension of decay in wooden logs. [ABSTRACT FROM AUTHOR]
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- 2018
- Full Text
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115. Etude expérimentale et numérique des systèmes ligneux en génie biologique pare-pierre
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Olmedo-Manich, I., Bourrier, Franck, Bertrand, D., Berger, F., Limam, A., Ecosystèmes montagnards (UR EMGR), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Université de Lyon-Institut National des Sciences Appliquées (INSA)
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[SDE]Environmental Sciences - Abstract
National audience; L’utilisation des arbres en travers comme systèmes de protection contre le chute de bloc et stabilisation du manteau neigeux est en train d’augmenter significativement. Ces systèmes temporaires et financièrement très intéressantes n’ont pas été étudiés jusqu’à l’actualité. L’objectif du projet de thèse « étude expérimentale et numérique des systèmes para bloc avec du bois mort (arbres en travers) » est d’analyser le rôle protecteur de ces ouvrages et la capacité de dissipation de l’énergie des pierres se propageant le long du versant.
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- 2012
116. Using a discrete model of root/soil interaction to quantify the protection of forest against shallow landslide and rockfall hazards
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Bourrier, Franck, Olmedo-Manich, I., Kneib, F., Ecosystèmes montagnards (UR EMGR), and Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)
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[SDE]Environmental Sciences - Abstract
International audience; In mountainous areas, forests may hold a protection function against natural hazards. To evaluate the influence of tree anchorage on these processes, a model of tree root system/soil interactions has been developed. The model, based on the Discrete Element Method (DEM), has been developed to identify the physical processes involved for shallow landslide and rockfall hazards. The soil is modelled as an assembly of rigid locally deformable spheres interacting at their contact points. The roots are either modelled as deformable cylindrical elements embedded into the soil for structural roots or by additional cohesive contact forces between the soil particles for fine roots. For shallow landslides, direct shear tests of rooted and non-rooted soils were modelled to identify the processes involved into roots reinforcement. The model presented can be potentially used to analyze the role played by root anchorage in the protection against other natural hazards (rockfall, in particular).
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- 2012
117. Felled trees as a rockfall protection system, experimental and numerical study
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Olmedo-Manich, I., Bourrier, Franck, Bertrand, D., Berger, F., Limam, A., Ecosystèmes montagnards (UR EMGR), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Université de Lyon-Institut National des Sciences Appliquées (INSA)
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[SDE]Environmental Sciences - Abstract
International audience; This research consists on an detailed study of the physical phenomena governing the impact between the rock and the tree stem, the mechanical resistance, the energy propagation into the felled tree and the evolution of these properties depending on wood degradation. The final aim of this research work is to develop an accurate numerical model that allows simulating the protective role of the felled trees in a wide range of situations.
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- 2012
118. Full scale field tests on rockfall impacting trees felled transverse to the slope
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Bourrier, Franck, Dorren, L., Berger, F., Ecosystèmes montagnards (UR EMGR), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), FEDERAL OFFICE FOR THE ENVIRONMENT FOEN BERN CHE, Partenaires IRSTEA, and Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)
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[SDE]Environmental Sciences - Abstract
International audience; To compensate for the temporary loss of protection due to the reduced forest in the felling area, a considerable part of the trees felled in rockfall protection forests are left in place. Although being a widely used technique, there is little objective information on the efficacy of these trees felled across the slope. To quantify the protective function of such structures, full scale rockfall tests on a protective structure made with trees felled across the slope were carried out. The results show significant energy losses when impacting the structure. However, the rock energy significantly increases again after the structure if the rock is not stopped. Consequently, a larger number of felled trees is required to stop all rocks and, to increase the number of stopped rocks, the structure height has to be determined in relation to the rock size which promotes, in most cases, structures made of stacked trees.
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- 2012
119. Kinectic energy dissipation effects of rock fall attenuating systems
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Glover, JERRY, Denk, M., Bourrier, Franck, Volkwein, A., Gerber, W., WSL BIRMENSDORF CHE, Partenaires IRSTEA, Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), GEOBRUGG AG ROMANSHORN CHE, Ecosystèmes montagnards (UR EMGR), and Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)
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[SDE]Environmental Sciences - Abstract
International audience; Attenuation, is the reduction in intensity of any flux through a medium. Rock fall attenuator systems are structures made of flexible wire netting designed reduce the intensity (kinetic energy) of rock fall and guide their trajectory. In order to evaluate the protective effect of an attenuating system and their capacity to absorb high energy impacts, high speed video recording methods have been applied to capture full scale rock rolling and attenuator barrier tests. The application of video methods requires that individual frames are scaled to the plane of the rock fall. Following this the rock fall trajectory and velocity over time can be extracted from the video. Herein, an assessment of the error in different approaches to video image scaling and position tracking for video analysis is made. Additionally the trajectories and velocity of rock falls from both un-attenuated rock rolling experiments and experiments testing the rock fall attenuator systems are analysed. A comparison of these data has allowed an assessment of the energy absorbed by the attenuator systems. Additionally, restitution coefficients for impacts on hard rock slopes have been drawn from the data, assisting in a simple model applied to estimation the attenuation effects of rock fall attenuator systems.
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- 2012
120. Gestion des forêts de protection et scanner laser aéroporté : cartographie des forêts de protection et modélisation des chutes de bloc
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Monnet, J.M., Berger, F., Clouet, N., Bourrier, Franck, Ecosystèmes montagnards (UR EMGR), and Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF)
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[SDE]Environmental Sciences ,SCANNER LASER AEROPORTE - Abstract
International audience; La gestion des forêts à fonction de protection est facilitée par la télédétection par scanner laser aéroporté. Les modèles de terrain et informations forestières qu'elle permet de cartographies sont en effet des variables cruciales pour la cartographie des forêts de protection et pour leur caractérisation par la simulation de chute de blocs.
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- 2011
121. Analyse expérimentale et numérique de la dynamique d'arbres verts de petits diamètres soumis à l'impact d'un bloc rocheux
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Bertrand, D., Bourrier, Franck, Brun, M., Berger, F., Association Française de Mécanique, Laboratoire de Génie Civil et d'Ingénierie Environnementale (LGCIE), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA), Ecosystèmes montagnards (UR EMGR), and Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF)
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[SDE]Environmental Sciences ,[PHYS.MECA]Physics [physics]/Mechanics [physics] - Abstract
National audience; Afin de mieux comprendre le rôle de protection des forêts de montagne contre les chutes de blocs, un modèle d'impact d'un bloc sur une tige de bois vert est proposé. Ce dernier est basé sur une modélisation par éléments finis (MEF) développée à partir du code libre CAST3M. Pour décrire l'interaction bloc/arbre, la cinématique et les phénomènes dissipatifs au cours de l'impact, les non-linéarités géométriques, matérielles et de contact sont prises en compte. En particulier, un algorithme de gestion du contact tige/bloc, basé sur la méthode des éléments discrets (MED), a été développé. La calibration est faite à partir d'essais d'impact à l'aide d'un pendule de Mouton-Charpy instrumenté. L'objectif de cette étude est de quantifier les échanges énergétiques et les modifications de la cinématique du bloc lors de l'impact, données très utiles pour prédire la trajectoire de blocs rocheux se propageant le long d'un talus boisé.
- Published
- 2011
122. Modelling the variability of rocks rebound on coarse soils
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Bourrier, Franck, Nicot, François, Berger, F., Darve, F., Ecosystèmes montagnards (UR EMGR), Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF), Érosion torrentielle, neige et avalanches (UR ETGR (ETNA)), Laboratoire sols, solides, structures - risques [Grenoble] (3SR), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Université Joseph Fourier - Grenoble 1 (UJF)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
[SDE]Environmental Sciences ,Physics::Geophysics - Abstract
Rockfall is a major risk in mountainous zones. In the field of falling rocks trajectory simulations, many scientific problems related to modelling the bouncing phase remain to be solved. The large variability of slope properties and boulder removal conditions pleads for a stochastic modelling of these trajectories. In particular, the rebound of falling rocks has to be modelled as a random process (Bourrier et al., 2009a). The aim of this study is to define a stochastic impact model that can capture the variability of the bouncing phenomenon on coarse soils, in particular. For this purpose, a numerical approach based on the Discrete Element Method (DEM) is used to investigate the impact of a boulder on a coarse granular soil in 2D. This model is used to perform an intensive simulations campaign. The analysis of results from this campaign is carried out using advanced statistical methods leading to the definition of a stochastic impact model. The stochastic impact model is finally integrated in a falling rocks trajectories simulation code and the code developed is evaluated by comparing real-scale experimental results to rockfall trajectory simulations.
- Published
- 2011
123. Combined use of innovative experiments and numerical models to assess tree stems resistance to rock impacts
- Author
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Bourrier, Franck, Bertrand, D., Brun, M., Berger, F., Ecosystèmes montagnards (UR EMGR), Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF), Laboratoire de Génie Civil et d'Ingénierie Environnementale (LGCIE), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)
- Subjects
[SDE]Environmental Sciences - Abstract
International audience; The use of rockfall protection forests is becoming a common practice in the European alps. Despite several recent research works, the estimation of the efficiency of standing trees and wooden protection structures remains very difficult. This efficiency is closely related to the resistance of - fresh, dry or decayed - tree stems to rock impacts. This resistance can be estimated from specific field experiments or from results from other research fields such as tree resistance to wind, for example. However, the impact of a standing or cut tree by a rock constitutes, from a mechanical point of view, a very complex and specific problem. Consequently, depending on the phytosanitary state of the stem, the type of structure impacted (standing trees or wooden structure), and the size and shape of the impacting rocks, specific studies should be done. In this context, the study presented aims at developing an innovative half-scale laboratory experiments to study the resistance of stems to rock impacts on different configurations in terms of tree properties (specie, dimensions ), projectile size and shape, and boundary conditions (fallen or standing trees). A methodology developed to use these experimental results is also presented for rock impacts on small fresh beech stems. This methodology consists in using the experimental results to calibrate a numerical model of impacts on fresh beech stems. The model calibrated can be used to design a rockfall wooden protection structure or to implement a tree interaction model into rockfall codes, for example.
- Published
- 2011
124. Quelle forêt pour les hommes ?
- Author
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Sardat, N., Curt, T., Ganteaume, A., Girard, F., Jappiot, M., Lampin, C., Long, M., Prévosto, Bernard, Ripert, C., Vennetier, M., Brahic, Elodie, Dehez, Jeoffrey, Deuffic, Philippe, Rambonilaza, Mbolatiana, Sergent, Arnaud, Terreaux, Jean-Philippe, Adra, W., Berger, F., Bigot, C., Bourrier, Franck, Breton, V., Brun, J.J., Chauvin, C., Clouet, N., Cordonnier, Thomas, Corona, C., Courbaud, Benoît, De Danieli, S., Defossez, E., Fuhr, M., Jancke, O., Kunstler, Georges, Lafond, Valentine, Lopez, J., Luque, Sandra, Monnet, J.M., Redon, M., Regolini, A., Rey, F., Saenger, A., Thiérion, Vincent, Vanpeene, S., Cernesson, Flavie, Chaffaut, I., Deshayes, M., Durrieu, S., Kosuth, Pascal, Ose, K., Archaux, Frédéric, Balandier, Philippe, Baldet, Patrick, Ballon, Philippe, Baltzinger, Christophe, Bergès, Laurent, Bouget, Christophe, Chevalier, Richard, Collin, E., Gosselin, Frédéric, Mårell, Anders, Lassauce, A., Paillet, Yoan, Perot, Thomas, Philippe, Gwenaël, Vallet, Patrick, Ecosystèmes montagnards (UR EMGR), Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF), Ecosystèmes méditerranéens et risques (UR EMAX), Aménités et dynamiques des espaces ruraux (UR ADBX), Services généraux (SGGR), Territoires, Environnement, Télédétection et Information Spatiale (UMR TETIS), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-AgroParisTech-Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF), and Écosystèmes forestiers (UR EFNO)
- Subjects
FORET ,BIODIVERSITE ,[SDE]Environmental Sciences ,GESTION PUBLIQUE ,FRAGFORNET ,TELEDETECTION ,INCENDIES ,RISQUES - Abstract
Dans ce livre, le Cemagref, institut de recherche en sciences et technologies pour l'environnement, fait le point de ses travaux scientifiques menés sur la forêt. Pourquoi une recherche sur la forêt ? D'abord parce qu'elle occupe plus d'un quart de la surface de notre territoire métropolitain. Ensuite, parce qu'elle fournit tout un ensemble de services variés et, pour certains, essentiels à notre société : la production de bois, la protection contre les aléas naturels, la chasse et la promenade en sont de très bonnes illustrations. Enfin, parce qu'elle constitue un milieu naturel riche en biodiversité et occupe une place notable dans les débats sur les enjeux environnementaux. Forts de ce constat, les chercheurs et experts du Cemagref apportent leur contribution en abordant des problématiques majeures pour la gestion durable des forêts : état et dynamique de la forêt, de sa biodiversité, vulnérabilité des forêts aux changements globaux et stratégies d'adaptation, gestion multifonctionnelle des forêts, rôle de protection contre les aléas naturels, place de la forêt dans les territoires et enjeux sociaux. L'interaction entre forêt et gestion se situe ainsi au c½ur de nos travaux.
- Published
- 2011
125. Probabilistic rockfall trajectory simulations including the protective effect of forests
- Author
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Bourrier, Franck, Dorren, L., Berger, F., Nicot, François, Darve, F., Ecosystèmes montagnards (UR EMGR), Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF), FEDERAL OFFICE FOR THE ENVIRONMENT FOEN BERN CHE, Partenaires IRSTEA, Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Érosion torrentielle, neige et avalanches (UR ETGR (ETNA)), Laboratoire sols, solides, structures - risques [Grenoble] (3SR), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Université Joseph Fourier - Grenoble 1 (UJF)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
[SDE]Environmental Sciences ,GeneralLiterature_MISCELLANEOUS ,Physics::Geophysics - Abstract
International audience; Classical rockfall simulations codes could be highly improved by defining models of the interactions between the falling rocks and the natural environment that integrate the variability associated with these interactions. Probabilistic models of the rebound of the rock on the soil and of the interaction of the rock with standing trees were developed. The probabilistic rebound model is based on the statistical analysis of numerical simulations of the impact of a rock on a soil using the Discrete Element Method. The procedure for the integration of the effect of forest is based on the probabilistic analysis of results from field experiments. The models allow the probabilistic calculation of the kinematics of the falling rock after interaction depending on the kinematics before interaction using a reduced number of easily identifiable field parameters. These models have been integrated into the trajectory simulation code Rockyfor3D. Comparisons of rockfall simulations using these models with field experiments have shown the efficiency of the approach.
- Published
- 2010
126. Predicting load path and tensile forces during cable yarding operations on steep terrain
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Dupire, Sylvain, primary, Bourrier, Franck, additional, and Berger, Frédéric, additional
- Published
- 2015
- Full Text
- View/download PDF
127. The effect of felled tree stems as bio-engineering type rockfall protection
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Bigot, Christophe, Bourrier, Franck, Berger, Frederic, Dorren, Luuk, Astrade, Laurent, Ecosystèmes montagnards (UR EMGR), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Federal Office for the Environment, Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), and Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)
- Subjects
dissipation d'énergie ,[SDE.IE]Environmental Sciences/Environmental Engineering ,couvert forestier ,[SDE]Environmental Sciences ,fonction de la foret ,foret de protection ,chute de pierres - Abstract
International audience; In mountainous regions forested slopes play an important protective role against rockfall. Up to now, most of the researches on rockfall protection forest have been and are focused on the dissipative effect of standing and living trees. There are hardly any studies on the protective capacity of tree stumps and lying stems against snow avalanches and rockfalls. Although, these techniques are more and more used throughout the Alps. In Austria, the felling technique Alpi has been developed, which allows a specialised lumberjack to create small rockfall barriers using one or two tree stems anchored on high tree stumps. Lying tree stems can be then used to increase efficiently the roughness of the soil and so to limit or avoid triggering and propagation falling rocks. But, due to the wood decay, the efficiency of such bio-engineering type protective works is decreasing with time. One of the questions that the forest and natural hazard managers have to answer is: what is the lifetime of such protective structures? In order to answer to this question we have developed a specific research on this thematic. The main objectives of this research program are to quantify the efficacy of these bio-engineering type rockfall fences depending on their characteristics (stump and stems density, position on the slope, tree species, etc.), and to evaluate their resistance over time. To achieve these objectives we have developed two types of experiments. The first one, performed during the summer 2009 on our experimental site test of Vaujany (France), are full scale rockfall experiments on four felled trees, which have been anchored on their stumps and are lying in an oblique direction to the slope. In total, fifty rocks (from 522 at 2242 kg) have been released one by one. For each rock, the trajectory has been filmed with high speed digital cameras. The second type of experiment is the uprooting of tree stumps (spruce, fir and beech) of different ages and diameter. To uproot the stumps we are using the same technique as for winching tests. For each experiment, stumps samples are taken in order to determine the wood decay ratio. Finally, a statistical analysis will be made in order to study the correlation between the force required to uproot a stump and its wood decay ratio. The first uprooting test campaign has been held during the summer 2009. First results of both experiment types will be presented. This study is part of the European Interreg IV Alpine Space project "MANFRED".
- Published
- 2010
128. Sylvaccess : un modèle pour cartographier automatiquement l’accessibilité des forêts
- Author
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Dupire, Sylvain, primary, Bourrier, Franck, additional, Monnet, Jean-Matthieu, additional, and Berger, Frédéric, additional
- Published
- 2015
- Full Text
- View/download PDF
129. Comparing numerical and experimental approaches for the stochastic modeling of the bouncing of a boulder on a coarse soil
- Author
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Bourrier, Franck, Nicot, François, Eckert, Nicolas, Darve, F., Érosion torrentielle, neige et avalanches (UR ETGR (ETNA)), Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF), Ecosystèmes montagnards (UR EMGR), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )
- Subjects
rockfall hazard ,[SDE]Environmental Sciences ,impact ,stochastic ,trajectory analysis ,discrete element method ,GeneralLiterature_MISCELLANEOUS - Abstract
International audience; This paper proposes numerical investigations for the stochastic modeling of a boulder impacting a coarse granular soil. The soil is considered as a noncohesive granular medium using a discrete element method and the soil model is calibrated compared to results from half-scale experiments. Based on this numerical model, an extensive numerical simulation campaign is carried out. The statistical analysis of the numerical results allows the definition of a stochastic bouncing model that quantifies most of the variability of the numerical results. Comparisons with classical bouncing models in the field of trajectory analysis highlight that this model expands classical approaches. The comparison of results from real-scale experiments to trajectory simulations based on the stochastic model show the relevance of the proposed approach to modeling rockfall trajectories.
- Published
- 2010
130. Analyse trajectographique des chutes de blocs, une approche stochastique
- Author
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Bourrier, Franck, Berger, F., Lambert, Stéphane, Nicot, François, Ecosystèmes montagnards (UR EMGR), Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF), and Érosion torrentielle, neige et avalanches (UR ETGR (ETNA))
- Subjects
[SDE]Environmental Sciences - Abstract
National audience; Dans ce chapitre, différentes approches de l'évaluation de l'aléa sont exposées. Certaines sont utilisées dans la pratique, d'autres, issues de la recherche, sont proposées dans l'objectif de rendre plus quantitative cette évaluation.
- Published
- 2010
131. Définition numérique du rebond d'une particule sur un lit granulaire
- Author
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Bourrier, Franck, Nicot, François, Darve, F., Érosion torrentielle, neige et avalanches (UR ETGR (ETNA)), Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF), Ecosystèmes montagnards (UR EMGR), and Centre National de la Recherche Scientifique (CNRS)
- Subjects
IMPACT ,[SDE]Environmental Sciences ,ONDE DE COMPRESSION ,REBOND - Abstract
International audience; The impact of a block on a coarse granular soil corresponding to rockfall events is investigated using the Discrete Element Method. Different impacting particle and medium characteristics are considered. Based on these numerical results, the impacting particle bouncing occurrence diagram is defined for various impacting particle sizes, incident kinematic parameters and sample heights. The bouncing occurrence diagram brings out three impact regimes. For a small impacting particle, the impact is mainly determined by the first interaction between the impacting particle and the soil, whereas for an intermediate-sized impacting particle, the compression wave propagation through the sample is the leading phenomenon. For large impacting particles, bouncing is associated with the formation of a compact layer below the impacting particle.
- Published
- 2009
132. Modeling the impact of a boulder on a natural soil, application to rockfall trajectory simulations
- Author
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Bourrier, Franck, Erosion torrentielle neige et avalanches (UR ETGR (ETNA)), Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Laboratoire sols, solides, structures - risques [Grenoble] (3SR), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Institut National Polytechnique de Grenoble - INPG, François Nicot, Félix Darve(francois.nicot@cemagref.fr, felix.darve@inpg.fr), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Université Joseph Fourier - Grenoble 1 (UJF)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS), Érosion torrentielle, neige et avalanches (UR ETGR (ETNA)), and Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF)
- Subjects
Rockfall ,Granular materials ,Trajectographie ,Trajectory analysis ,Matériaux granulaires ,Stochastic analysis ,Méthode des Eléments Discrets ,Inférence Bayésienne ,Chute de blocs ,[SPI]Engineering Sciences [physics] ,Impact ,Discrete Element Method ,Bayesian inference ,Analyse stochastique - Abstract
This thesis is dedicated to the study of falling rocks bouncing on natural soils in order to improve the models used for rockfall hazard assessment. The impact of a rock on a scree slope is modelled using the Discrete Element Method. The comparison between numerical results and half-scale experimental results of impacts on a coarse soil shows that the numerical model allows accurately predicting the bouncing of the rock for a reduced number of model parameters to be calibrated. The numerical results also emphasize that the interaction between the impacting particle and the granular soil is composed of three stages : the partial energy exchange from the impacting particle to the soil, the propagation of a shockwave from the impact point and the wave reflection on the substratum. The study of energy exchanges during these three stages allows defining the impacting particle bouncing occurrence diagram as well as three impact regimes. The statistical analysis of numerical results using Bayesian inference leads to the definition of a stochastic impact model. This model is relevant for rock velocity after impact depending on both rock velocity before impact and soil particles layout near the impact point. Finally, the stochastic impact model is integrated into trajectory analysis models which allows defining a global probabilistic approach of rockfall hazard assessment including protective structures design.; Ce travail de thèse porte sur la caractérisation du rebond d'un bloc sur un terrain naturel dans la perspective d'améliorer les modèles de détermination de l'aléa de chute de blocs. L'impact d'un bloc rocheux sur un sol composé d'éboulis est modélisé par la Méthode des Elements Discrets. La comparaison entre les résultats de simulation et les résultats d'essais à échelle réduite d'impact sur un sol granulaire grossier met en évidence que le modèle numérique développé assure une prédiction pertinente du rebond pour un nombre réduit de paramètres de simulation à calibrer. L'analyse de l'impact à l'aide du modèle numérique montre que l'interaction entre l'impactant et le sol peut être décomposée en trois phases : le transfert énergétique initial du bloc vers le sol, la propagation d'une onde de compression du point d'impact vers l'intérieur du sol et la réflexion de l'onde de compression sur le substratum. L'étude des échanges énergétiques lors de ces trois phases conduit à la définition d'un diagramme d'existence du rebond délimitant les domaines d'arrêt et de rebond de l'impactant et à l'identification de trois régimes d'impact. Le traitement statistique des résultats de simulation par des méthodes statistiques basées sur l'inférence Bayésienne permet également de définir une loi d'impact stochastique. Cette loi est représentative de la variabilité des vitesses du bloc après impact en fonction des paramètres cinématiques incidents et de l'arrangement géométrique des particules du sol au voisinage du point d'impact. Enfin, suite à l'intégration de la loi stochastique d'impact dans le contexte de l'analyse trajectographique, une approche probabiliste globale permettant la caractérisation détaillée de l'aléa de chute de bloc ainsi que l'implantation et le dimensionnement d'ouvrages de protection est proposée.
- Published
- 2008
133. Cadre stochastique pour la modélisation d'un bloc sur un éboulis
- Author
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Bourrier, Franck, Nicot, François, Darve, F., Érosion torrentielle, neige et avalanches (UR ETGR (ETNA)), Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF), and Centre National de la Recherche Scientifique (CNRS)
- Subjects
[SDE]Environmental Sciences - Abstract
International audience; Rockfall hazard assessments are increasingly done using trajectory analysis. A key parameter in such approaches is the modelling of the interaction between the falling rock and the soil. The presented study focuses on this phase in the case of a boulder impacting a scree slope. In the context of trajectory analysis, the available information on the local configuration of soil particles near the impact point and on the incident kinematic parameters of the boulder are not sufficient to perform a deterministic prediction of boulder bouncing. Stochastic approaches are then necessary to properly model the impact phase. Numerical investigtions using a Discrete Element Method are performed in order to investigate the impact process. The statistical treatment of the results leads to the definition of a stochastic impact model linking the block kinematics parameters before and after its interaction with the granular soil. The comparison between the predictions of the model and the results from half-scale experiments emphasizes the relevance of a predictive use of the stochastic impact model and the interest of using stochastic approaches in the field of trajectory analysis.
- Published
- 2008
134. Vers une modélisation réaliste de la trajectographie des chutes de blocs à partir d'un algorithme stochastique de rebond
- Author
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Dorren, L., Bourrier, Franck, Nicot, François, Berger, F., Darve, F., Ecosystèmes montagnards (UR EMGR), Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF), Érosion torrentielle, neige et avalanches (UR ETGR (ETNA)), and Centre National de la Recherche Scientifique (CNRS)
- Subjects
[SDE]Environmental Sciences - Abstract
International audience; A challenge in rockfall modelling is to develop a robust rebound algorithm for which parame-ter values can be estimated objectively in the field. In this paper, we tackle this challenge by presenting and testing a stochastic impact law that requires limited parameterisation by the model user. The approach provides promising results. We will present the simulation results and their validation as well as remaining unknowns and future developments.
- Published
- 2008
135. Numerical modelling of physical processes involved during the impact of a rock on a coarse soil
- Author
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Bourrier, Franck, Eckert, Nicolas, Bellot, H., Heymann, A., Nicot, François, Darve, F., Érosion torrentielle, neige et avalanches (UR ETGR (ETNA)), Centre national du machinisme agricole, du génie rural, des eaux et forêts (CEMAGREF), and Centre National de la Recherche Scientifique (CNRS)
- Subjects
[SDE]Environmental Sciences ,Physics::Geophysics - Abstract
International audience; Rockfall hazard assessments are increasingly done with rockfall numerical simulations. A key parameter in such models is the modelling of the interaction between the falling rock and the soil. The presented approach focuses on the impact phase modelling in the case of the interaction of a boulder with a coarse granular soil. The soil is modeled as a non cohesive granular medium using the Discrete Element Method. The statistical analysis of numerical results is carried out using Bayesian methods which leads to the definition of a stochastic impact model. The relevance of a predictive use of the model is evaluated by comparing the reflected velocities predicted by the model to results from half-scale experiments.
- Published
- 2008
136. Caractérisation numérique d'une loi stochastique d'impact d'un bloc rocheux sur un éboulis
- Author
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Bourrier, Franck, NICOT, François, Darve, Félix, and Association Française de Mécanique
- Subjects
Milieu granulaire ,Chute de blocs ,Impact ,DEM ,[PHYS.MECA]Physics [physics]/Mechanics [physics] - Abstract
Colloque avec actes et comité de lecture. Internationale.; International audience; Les logiciels de trajectographie constituent un outil indispensable pour la détermination des zones soumises à un risque de chute de bloc en zones montagneuses. Une amélioration fondamentale à apporter à ces codes de calcul est la caractérisation fine du rebond du bloc sur le sol. Dans cette optique, une modélisation numérique de l'interaction entre le bloc et le sol par la Méthode des Elements Discrets est développée de façon à étudier l'impact d'un bloc rocheux sur un éboulis. Le traitement statistique des résultats issus des simulations numériques permet de définir une loi d'impact stochastique valable quels que soient le point d'impact et les conditions cinématiques initiales du bloc.
- Published
- 2007
137. Improving Rebound Models in 3D Rockfall Simulation Codes Used for the Design of Protection Embankments
- Author
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Toe, David, primary, Lambert, Stéphane, additional, Bourrier, Franck, additional, and Berger, Frédéric, additional
- Published
- 2014
- Full Text
- View/download PDF
138. Felled Trees as a Rockfall Protection System, Experimental Study for Numerical Models Calibration
- Author
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Olmedo, I., primary, Bourrier, Franck, additional, Bertrand, D., additional, Berger, Frédéric, additional, and Limam, Ali, additional
- Published
- 2014
- Full Text
- View/download PDF
139. Three-dimensional modelling of slope stability in heterogeneous montane forest ecosystems
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Mao, Zhun, primary, Bourrier, Franck, additional, Stokes, Alexia, additional, and Fourcaud, Thierry, additional
- Published
- 2014
- Full Text
- View/download PDF
140. Discrete modeling of granular soils reinforcement by plant roots
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Bourrier, Franck, primary, Kneib, François, additional, Chareyre, Bruno, additional, and Fourcaud, Thierry, additional
- Published
- 2013
- Full Text
- View/download PDF
141. Managing coppice forests for rockfall protection: lessons from modeling
- Author
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Radtke, Anna, primary, Toe, David, additional, Berger, Frederic, additional, Zerbe, Stefan, additional, and Bourrier, Franck, additional
- Published
- 2013
- Full Text
- View/download PDF
142. Rockfall Dynamics: A Critical Review of Collision and Rebound Models
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Bourrier, Franck, primary and Hungr, Oldrich, additional
- Published
- 2013
- Full Text
- View/download PDF
143. Inertia effects as a possible missing link between micro and macro second-order work in granular media
- Author
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Nicot, François, primary, Hadda, Nejib, additional, Bourrier, Franck, additional, Sibille, Luc, additional, Wan, Richard, additional, and Darve, Félix, additional
- Published
- 2012
- Full Text
- View/download PDF
144. Toward objective rockfall trajectory simulation using a stochastic impact model
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Bourrier, Franck, primary, Dorren, Luuk, additional, Nicot, François, additional, Berger, Frédéric, additional, and Darve, Félix, additional
- Published
- 2009
- Full Text
- View/download PDF
145. Modelling and predicting the spatial distribution of tree root density in heterogeneous forest ecosystems.
- Author
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Mao, Zhun, Saint-André, Laurent, Bourrier, Franck, Stokes, Alexia, and Cordonnier, Thomas
- Subjects
PLANT roots ,TREES ,PLANT spacing ,MOUNTAIN ecology ,NORWAY spruce ,PLANT growth ,MATHEMATICAL models - Abstract
* Background and Aims In mountain ecosystems, predicting root density in three dimensions (3-D) is highly challenging due to the spatial heterogeneity of forest communities. This study presents a simple and semi-mechanistic model, named ChaMRoots, that predicts root interception density (RID, number of roots m
-2 ). ChaMRoots hypothesizes that RID at a given point is affected by the presence of roots from surrounding trees forming a polygon shape. * Methods The model comprises three sub-models for predicting: (1) the spatial heterogeneity - RID of the finest roots in the top soil layer as a function of tree basal area at breast height, and the distance between the tree and a given point; (2) the diameter spectrum -- the distribution of RID as a function of root diameter up to 50mm thick; and (3) the vertical profile -- the distribution of RID as a function of soil depth. The RID data used for fitting in the model were measured in two uneven-aged mountain forest ecosystems in the French Alps. These sites differ in tree density and species composition. * Key Results In general, the validation of each sub-model indicated that all sub-models of ChaMRoots had good fits. The model achieved a highly satisfactory compromise between the number of aerial input parameters and the fit to the observed data. * Conclusions The semi-mechanistic ChaMRoots model focuses on the spatial distribution of root density at the tree cluster scale, in contrast to the majority of published root models, which function at the level of the individual. Based on easy-to-measure characteristics, simple forest inventory protocols and three sub-models, it achieves a good compromise between the complexity of the case study area and that of the global model structure. ChaMRoots can be easily coupled with spatially explicit individual-based forest dynamics models and thus provides a highly transferable approach for modelling 3-D root spatial distribution in complex forest ecosystems. [ABSTRACT FROM AUTHOR]- Published
- 2015
- Full Text
- View/download PDF
146. To Which Extend the Failure Mode Originates from Microstructure?
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Nicot, François, Hadda, Nejib, Bourrier, Franck, Sibille, Luc, and Darve, Félix
- Published
- 2013
- Full Text
- View/download PDF
147. Quantile-based individual risk measures for rockfall-prone areas.
- Author
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Farvacque, Manon, Eckert, Nicolas, Bourrier, Franck, Corona, Christophe, Lopez-Saez, Jérôme, and Toe, David
- Abstract
In mountain environments, precise rockfall risk evaluation is crucial to reduce death tolls and costs. However, to date, existing rockfall risk assessment procedures remain scarce, as they focus only on existing elements at risk and with the damage expectation as sole risk measure. Here, we propose an approach to evaluate the distribution of damages on an individual basis as a continuous function of space. Furthermore, rockfall risk is evaluated through (i) the damage expectation and based on (ii) the value-at-risk (VAR) and (iii) the expected shortfall (ES). VaR and ES risk measures allow better assessing the risk due to extreme events and accounting for various short-term/long-term constraints faced by stakeholders. This procedure is applied to Le Brocey slope (municipality of Crolles, French Alps), frequently affected by rockfall events, illustrating its potential for land-use planning. Notably, obtained individual risk values can be confronted with acceptability thresholds to perform legal zoning on sound basis. Also, they allow comparison of risk management strategies as function of different behaviors towards risk, budgetary constraints and/or temporal horizons. Hence, the approach provides valuable tools for future land-use planning and decision-making. It could easily be transferred to other hazards as a wider contribution to the determination of the best balance between safety and sustainability. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
148. Coulomb friction with rolling resistance as a cone complementarity problem.
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Acary, Vincent and Bourrier, Franck
- Subjects
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ROLLING friction , *COULOMB friction , *CONES , *MATHEMATICAL ability , *GRAVITY - Abstract
Coulomb friction model with unilateral contact is a basic, but reliable, model to represent the resistance to sliding between solid bodies. It is nowadays well-known that this model can be formulated as a second–order cone complementarity problem, or equivalently, as a variational inequality. In this article, the Coulomb friction model is enriched to take into account the resistance to rolling, also known as rolling friction. Introducing the rolling friction cone, an extended Coulomb's cone, and its dual, a formulation of the Coulomb friction with rolling resistance as a cone complementarity problem is shown to be equivalent to the standard formulation of the Coulomb friction with rolling resistance. Based on this complementarity formulation, the maximum dissipation principle and the bi-potential function are derived. Several iterative numerical methods based on projected fixed point iterations for variational inequalities and block-splitting techniques are given. The efficiency of these methods strongly relies on the computation of the projection onto the rolling friction cone. In this article, an original closed-form formula for the projection on the rolling friction cone is derived. The abilities of the model and the numerical methods are illustrated on the examples of a single sphere sliding and rolling on a plane, and of the evolution of spheres piles under gravity. • Formulation of the Coulomb friction with rolling resistance as a cone complementarity problem. • Derivation of the maximum dissipation principle and the bi-potential function. • Iterative numerical methods based on projected _xed point iterations for variational inequalities and block-splitting techniques are given. • An original closed-form formulae for the projection on the rolling friction cone is derived. • Examples of a single sphere sliding and rolling on a plane, and of the evolution of spheres piles under gravity. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
149. Machine learning prediction of the mass and the velocity of controlled single-block rockfalls from the seismic waves they generate.
- Author
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Hibert, Clément, Noël, François, Toe, David, Talib, Miloud, Desrues, Mathilde, Wyser, Emmanuel, Brenguier, Ombeline, Bourrier, Franck, Toussaint, Renaud, Malet, Jean-Philippe, and Jaboyedoff, Michel
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SEISMIC waves , *MACHINE learning , *ATTENUATION of seismic waves , *VELOCITY , *SEISMIC networks - Abstract
Understanding the dynamics of slope instabilities is critical to mitigate the associated hazards, but their direct observation is often difficult due to their remote locations and their spontaneous nature. Seismology allows us to get unique information on these events, including on their dynamics. However, the link between the properties of these events (mass and kinematics) and the seismic signals generated is still poorly understood. We conducted a controlled rockfall experiment in the Riou Bourdoux torrent (southern French Alps) to try to better decipher those links. We deployed a dense seismic network and inferred the dynamics of the block from the reconstruction of the 3D trajectory from terrestrial and airborne high-resolution stereophotogrammetry. We propose a new approach based on machine learning to predict the mass and the velocity of each block. Our results show that we can predict those quantities with average errors of approximately 10 % for the velocity and 25 % for the mass. These accuracies are as good as or better than those obtained by other approaches, but our approach has the advantage in that it does not require the source to be localised, nor does it require a high-resolution velocity model or a strong assumption on the seismic wave attenuation model. Finally, the machine learning approach allows us to explore more widely the correlations between the features of the seismic signal generated by the rockfalls and their physical properties, and it might eventually lead to better constraints on the physical models in the future. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
150. Real-size rockfall experiment: Applying observed impact dynamics to 3D rockfall simulations on highly detailed terrain models.
- Author
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Noël, François, Wyser, Emmanuel, Jaboyedoff, Michel, Hibert, Clément, Talib, Miloud, Malet, Jean-Philippe, Toussaint, Renaud, Desrues, Mathilde, Bourrier, Franck, Toe, David, Brenguier, Ombeline, Gracchi, Teresa, Derron, Marc-Henri, Cloutier, Catherine, and Locat, Jacques
- Published
- 2019
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