Modelling rockfall impact with scarring in compactable soils

Lu, GX; Caviezel, Andrin; Christen, Marc; Demmel, Sophia E.; Ringenbach, Adrian; Bühler, Yves; Dinneen, Claire E.; Gerber, Werner; Bartelt, Perry

doi:10.1007/s10346-019-01238-z

Cited by 31 publications

(26 citation statements)

References 28 publications

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“…It confirms the intuition, that soil impacts of faster projectiles dissipate more energy as they generally penetrate further into the soil for equivalent soil conditions than smaller rocks. This is owing to the fact, that the compressibility of the impacted soil is limited to a velocity-dependent maximal penetration depth 44 . This maximal penetration depth is dependent on soil composition and impact configuration, meaning larger and faster rocks produce larger scars upon impact.…”

Section: Resultsmentioning

confidence: 99%

The relevance of rock shape over mass—implications for rockfall hazard assessments

Caviezel¹,

Ringenbach²,

Demmel³

et al. 2021

Nat Commun

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The mitigation of rapid mass movements involves a subtle interplay between field surveys, numerical modelling, and experience. Hazard engineers rely on a combination of best practices and, if available, historical facts as a vital prerequisite in establishing reproducible and accurate hazard zoning. Full-scale field tests have been performed to reinforce the physical understanding of debris flows and snow avalanches. Rockfall dynamics are - especially the quantification of energy dissipation during the complex rock-ground interaction - largely unknown. The awareness of rock shape dependence is growing, but presently, there exists little experimental basis on how rockfall hazard scales with rock mass, size, and shape. Here, we present a unique data set of induced single-block rockfall events comprising data from equant and wheel-shaped blocks with masses up to 2670 kg, quantifying the influence of rock shape and mass on lateral spreading and longitudinal runout and hence challenging common practices in rockfall hazard assessment.

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Section: Resultsmentioning

confidence: 99%

The relevance of rock shape over mass—implications for rockfall hazard assessments

Caviezel¹,

Ringenbach²,

Demmel³

et al. 2021

Nat Commun

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“…The initial rock orientation was the only varying input parameter. The same soil conditions as well as the same time step (0.002 s) was employed for both the explicit and the implicit scheme [17]. Figure 5 visualizes the maximal kinetic rock energy of the simulation ensemble of the thousand trajectories using the statistic mode of RAMMS::ROCKFALL for the explicit scheme and for the new implicit scheme (Figs.…”

Section: Idealized Inclined Slopementioning

confidence: 99%

Stability of rigid body motion through an extended intermediate axis theorem: application to rockfall simulation

Leine

Capobianco

Bartelt³

et al. 2021

Multibody Syst Dyn

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The stability properties of a freely rotating rigid body are governed by the intermediate axis theorem, i.e., rotation around the major and minor principal axes is stable whereas rotation around the intermediate axis is unstable. The stability of the principal axes is of importance for the prediction of rockfall. Current numerical schemes for 3D rockfall simulation, however, are not able to correctly represent these stability properties. In this paper an extended intermediate axis theorem is presented, which not only involves the angular momentum equations but also the orientation of the body, and we prove the theorem using Lyapunov’s direct method. Based on the stability proof, we present a novel scheme which respects the stability properties of a freely rotating body and which can be incorporated in numerical schemes for the simulation of rigid bodies with frictional unilateral constraints. In particular, we show how this scheme is incorporated in an existing 3D rockfall simulation code. Simulations results reveal that the stability properties of rotating rocks play an essential role in the run-out length and lateral spreading of rocks.

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“…The reader is referred to Lu et al (Lu et al 2018) for a detailed comparison of the pros and cons of these two methods. The implementation of the non-smooth mechanics modelling for rockfall on an arbitrary slope was addressed elsewhere (Leine et al 2014;Lu et al 2019). The main aspect will only be shortly presented in the following sections.…”

Section: Interactionsmentioning

confidence: 99%

“…The contact detection routine is distinguished into two paths: DCT (Direct Contact Test) and SAT (Separating Axis Test), depending on the spherical or nonspherical rock shape. The interaction between a rock and a tree stem is considered as hard contact (Leine et al 2014;Lu et al 2019), preventing the rock from further penetrating into the tree stem; thus the energy dissipation of the rock caused by the uprooting and the swaying of tree stem/crown is not incorporated. In order to efficiently identify collisions between non-spherical rocks and tree stems, a global contact detection phase is in general required by performing AABB (Axis Aligned Bounding Box) tests (Lu et al 2012).…”

Section: Rock-tree Contact Detection Modelsmentioning

confidence: 99%

Mitigation effects of trees on rockfall hazards: does rock shape matter?

Lu¹,

Ringenbach²,

Caviezel³

et al. 2020

Landslides

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Does rock shape matter to the mitigation effects of trees on rockfall hazards? This question must be resolved in order to better quantify the protective role of mountain forests against rockfall. To probe this question we investigate a single rock-tree interaction using non-smooth, hard-contact mechanics that allows us to consider rock shape at impact. The interaction of equant shaped rocks with cylinder-like tree stems is modelled. The equant shaped rocks are close to spherical but have a certain shape variability governed by the rock's surface area ratio and aspect ratio. This work serves as an important follow-up study to the existing investigations from Toe et al. (Landslides 14: 1603(Landslides 14: -1614(Landslides 14: , 2017, where the effects of trees on block propagation are numerically investigated using spherical shaped rocks. The objective of our simulations is to understand how and to what extent, shape will influence energy dissipation and trajectory change. The primary results include: surface area ratio plays a more important role than aspect ratio in determining the rock's post-impact dynamics. The primary parameters governing the rock kinematics after impact (i.e. block's energy reduction, reflected rotational

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Modelling rockfall impact with scarring in compactable soils

Cited by 31 publications

References 28 publications

The relevance of rock shape over mass—implications for rockfall hazard assessments

The relevance of rock shape over mass—implications for rockfall hazard assessments

Stability of rigid body motion through an extended intermediate axis theorem: application to rockfall simulation

Mitigation effects of trees on rockfall hazards: does rock shape matter?

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