Perforation of Flexible Rockfall Barriers by Normal Block Impact

Flexible rockfall barriers are a common form of protection against falling blocks of rock and rock fragments (rockfall). These barriers consist of a system of cables, posts, and a mesh, and their capacity is typically quantified in terms of the threshold of impact (kinetic) energy at which the barri...

Full description

Saved in:
Bibliographic Details
Published in:Rock mechanics and rock engineering 2013-05, Vol.46 (3), p.515-526
Main Authors: Hambleton, J. P., Buzzi, O., Giacomini, A., Spadari, M., Sloan, S. W.
Format: Article
Language:English
Subjects:
Barriers
Blocking
Civil Engineering
Earth and Environmental Science
Earth Sciences
Energy
Environmental impact
Geophysics/Geodesy
Kinetics
Mathematical analysis
Mathematical models
Original Paper
Rock
Rockfall
Rocks
Thresholds
Wire mesh
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Flexible rockfall barriers are a common form of protection against falling blocks of rock and rock fragments (rockfall). These barriers consist of a system of cables, posts, and a mesh, and their capacity is typically quantified in terms of the threshold of impact (kinetic) energy at which the barrier fails. This threshold, referred to here as the “critical energy,” is often regarded as a constant. However, several studies have pointed out that there is no single representative value of critical energy for a given barrier. Instead, the critical energy decreases as the block size decreases, a phenomenon referred to as the “bullet effect.” In this paper, we present a simple analytical model for determining the critical energy of a flexible barrier. The model considers a block that impacts normally and centrally on the wire mesh, and rather than incorporate the structural details of the cables and posts explicitly, the supporting elements are replaced by springs of representative stiffness. The analysis reveals the dependence of the critical energy on the block size, as well as other relevant variables, and it provides physical insight into the impact problem. For example, it is shown that bending of the wire mesh during impact reduces the axial force that can be sustained within the wires, thus reducing the energy that can be absorbed. The formulas derived in the paper are straightforward to use, and the analytical predictions compare favorably with data available in the literature.
ISSN:0723-2632
1434-453X
DOI:10.1007/s00603-012-0343-x