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| Titel |
Numerical modelling of new rockfall interception nets |
| VerfasserIn |
Albrecht von Boetticher, Axel Volkwein, Corinna Wendeler |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250043821
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| Zusammenfassung |
| The design and certification of effective rockfall protection barriers is mainly achieved
through 1:1 prototype testing. In order to reduce development costs of a prototype it is
recommended that pre-studies using numerical simulations are performed. A large
component to modelling rockfall protection systems is the numerical simulation of the nets.
To date there exist several approaches to model the different mesh types such as
ring nets or diagonal meshes (Nicot 1999, Cazzani et al. 2002, Volkwein 2004).
However, the consideration of chain link meshes has not yet been realised. Chain link
meshes are normally found as standard fence structures. However, they also exist in
setups using high-strength steel and wire bundles. These variants show an enormous
capacity to retain loads e.g. rockfalls, and at the same time are very efficient due to
their low demand of steel material. The increasing application of chain link mesh
in barrier systems requires an accurate model is available to complete prototype
studies.
A new approach now aims to perform a Finite Element simulation of such chain link
meshes. The main challenge herein is to achieve the net deformation behaviour that is
observed in field tests also in the simulation. A simulation using simple truss elements would
not work since it neglects the out-of-plane-height of the mesh construction providing
important reserves for local and global high deformations. Thus addressing this, a specially
developed Discrete Element is able to reconstruct the mechanical behaviour of the single
chain wire (bundles). As input parameters it utilises typical properties such as longitudinal
and transversal mesh widths, and break loads resulting from in-plane-tension tests and steel
strength. The single chain elements then can be combined to a complete mesh (e.g.
130 x 65 mm, 3 -  4 mm wire with a strength of 1770 N-mm2). Combining these
elements with a supporting structure consisting of posts, ropes and energy absorbers, enables
the simulation of protection barriers used for natural hazards such as rockfalls or even
landslides.
The contribution explains the mechanical behaviour of the chain mesh, the calibration
procedures and their application in flexible rockfall protection systems. The investigated
meshes are built using three or four millimeter wire with a minimum yield strength of
1770Â N-mm2: The maximal load in longitudinal mesh direction ranges about
130Â - Â 380Â kN-m and transversal 50Â - Â 170Â kN-m. The mesh size varies from
83Â Ã Â 143Â mm to 292Â Ã Â 500Â mm.
References
Cazzani, A., Mongiovi, L. and Frenez, T. (2002) Dynamic Finite Element Analysis of
Interceptive Devices for Falling Rocks, International Journal of Rock Mechanics & Mining
Sciences. 39,303-321.
Volkwein, A. (2004) Numerische Simulation von flexiblen Steinschlagschutzsystemen.
Diss. ETH Nr. 15641.
Nicot, F. (1999) Etude du comportement méchanique des ouvrages souples de protection
contre les éboulements rocheux. Diss. Ecole Centrale de Lyon. |
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