3000 k J
We developed dynamic barriers
for rockfall protection.
Leading the ﬁeld thanks to
- ROCCO® ring net technology
- maximum energy absorption
(ﬁeld tested / certiﬁed for
impact energies up to 3000 kJ)
- dimensionable protection
systems (also for 100 year
- longest useful life thanks to
Prevention at any price? Intercepting
and catching are more economical.
Since 1951 we have continued uncompromising development; since 1981 we have been regularly analyzing
barrier behavior in ﬁeld tests of rockfall events. Today
our dynamic barrier systems are capable of absorbing
impact energies of up to 5000 kJ. For example, consider
a block of rock weighing 16 metric tons traveling at 90
km/h. With the ROCCO® steel wire ring nets and our
OPTUS® planning concept, we can design modular
protection systems – project-speciﬁc, tailored to your
hazard po-tential, customized to your protection needs
and econo-mically optimized.
In the absence of forestation as
a natural protective shield
Forests offer the best protection against rockfall. Where
it is lacking, or if it is inadequate, protective structures
must assume this function. Conventional fortifying and
stabilizing measures (shotcrete, nailing, slope covers
etc.) only partially address the causes, but can never
completely prevent rockfall events. What’s more, these
solutions usually turn out to be very expensive. Our
barrier systems are based on the idea that they are
considerably more economical and effective at protecting
people and infrastructures from the consequences of
rockfall, namely by absorbing the kinetic (movement)
Traces left by earlier events usually allow to calculate
velocity and geometry of future possible rockfall events.
Also, rocks and boulders found at the base of the slope
provide information on the hazard potential. These factors
are used to assess the risk before we plan appropriate
protective measures, and we verify them with rockfall
Conﬁdence, yes, but scientiﬁcally based tests are a must.
In late May 2001, we commissioned the world’s ﬁrst
government recognized test facility for vertical fall
(impact velocity 25 m/s or 90 km/h). There our
Geobrugg RX-300 high energy protective barrier with
ROCCO® steel wire ring nets and DIMO® braking system
successfully stood up to the impact of a thrown concrete
body weighing 9640 kg, resulting in an impact energy
We ﬁeld test our barrier systems with impact energies
of 3000 kJ. This made RX-300 the ﬁrst high energy
up to 5000 kJ.
protective barrier to be tested – and certiﬁed – by the
Federal Expert Commission on Avalanches and Rockfall
(FECAR) according to the internationally respected
guidelines of the Swiss government Agency for the
dynamic barrier systems…
… as protection against falling trees, snow sluffs
… as an economical alternative to dams, galleries,
tunnels or road realignments
Vertical and inclined fall: tests by various independent international institutions such as Caltrans ( California Department
of Transportation) or JR (Japan Rail) have conﬁrmed the performance of our barrier systems.
… as temporary installations on road or tunnel
construction sites, in tunnels and mines
Because fractions of a second count in
emergencies: six system components
that interact perfectly.
The only rigid component in our systems is the steel
post, which is mounted with a hinge pin on a ground
plate that is anchored in the ground. The posts hold
the elastic ring nets in the correct position. In a hazard
event, the ring nets are the ﬁrst to absorb energy; the
rings deform to their extension limit, then pass on the
residual energy to the braking elements in the bearing,
anchor and retaining ropes. The optimal interaction of
all components determines the maximum capacity for
1) The ROCCO® steel wire ring net
Compared with conventional protective nets the ROCCO®
ring net, with its four-fold suspension, stands out for its
outstanding energy absorption properties. In a rockfall
event, a signiﬁcant portion of the kinetic energy is
dissipated over the sum of deformation of all of the
rings. The forces are evenly passed on to the net and
the entire system, without placing an extreme strain on
the anchorages. In the impact zone within split seconds
the ring net – ﬁxed to the ropes by means of shackles
– automatically reinforces itself perfectly with a higher
density of ring bundles.
The rings have a diameter of 300 mm and are made of
high tensile-strength 3 mm diameter steel wire. Between
7 and 16 spirals are bundled together, depending on the
desired energy absorption capacity.
4) Bearing, anchoring and
2) The ground plates
3) The steel posts
The anchoring system for the steel bearing posts is
The systems utilize HEB proﬁles for barrier heights of 2 to
adapted to the local ground conditions (unconsolidated /
7 m, which are fastened to the ground plate with a hinge
Steel wire ropes hold the steel posts and ring nets in the
pin. These hinge pins act as predetermined breaking
correct position for the existing terrain conditions.
points and protect the anchorage from destruction in case
Shackles are used to fasten the ring nets to the upper and
the posts are directly impacted from falling objects.
lower bearing ropes. The steel posts are anchored
laterally to the ground with anchor ropes and in back
with retaining ropes. Depending on the hazard and
energy potential, these ropes may be doubled or
quadrupled, using diameters between 12 and 22 mm.
The alarm system reports
5) The brake rings
6) The spiral rope anchor
Where necessary the bearing, anchoring and retaining
Because ﬂexible elements are essential for rockfall
ropes are guided through pipes bent into loops, which act
protective structures, we recommend the use of anchors
as brake rings. In larger rockfall events as they contract,
made of high-strength steel wires with a tensile strength
these brake rings dissipate the residual energy without
of 1770 N/mm2. In contrast to conventional steel
damaging the ropes.
anchor bars, they are protected by a steel tube against
Our structures can be equipped or retroﬁtted
mechanical damage caused by falling rocks and are able
with a system that transmits a signal in case of a
to transmit forces in the pulling direction that can deviate
rockfall event. Its ﬁeld-tested functionality is as
by up to 30 degrees from the borehole axis without any
simple as it is reliable.
loss of load-bearing capacity.
The DIMO® brake concept: keep energies
up to and over 3000 kJ under control
and the system damage within limits.
Ground plates with round half-shells to hold the posts,
predetermined breaking points on the post heads,
multiple bearing, anchor and retaining ropes, brake
rings, net suspensions with shackles, and the ROCCO®
ring nets with their four-fold suspension: These individual
elements combine into the DIMO® brake concept, which
is based on a whole range of well thought-out detailed
solutions that together guarantee optimal effect. This
construction of the individual components is based
on knowledge gained from years of research and
scientiﬁcally evaluated test series.
Extremely short braking distance
Even in the case of a maximum rockfall event of 9640
kg, impact velocity of 90 km/h and an energy of 3000
kJ, thanks to DIMO® with for instance 10 m post spacing
the ring net is only deﬂected 6.6 m – because more
energy is dissipated via step-wise dosing (through
planned predetermined breaking points in case of large
rockfall events). For these high energies, the built-in
curtain effect typical for Geobrugg barriers is thereby
delayed with DIMO® and the ring net deﬂection is
minimized. See graph 2 next page. Thus, our structures
can be installed closer to the object to be protected,
simplifying both installation and maintenance, and
thereby reducing costs. Furthermore, the effective height
is better conserved after a rockfall event, making its
protection fully available for the next event.
Systematically dissipating the
If an object impacts the protective structure, the elements
are strained in the following order: ring net, brake
rings, bearing ropes and posts. This means that minor
events usually have no consequence – and after a major
event, if at all only the affected components must be
replaced. To this end, built-in predetermined breaking
points protect the most expensive system components
Graph 1: Force/displacement diagram
The braking process represented
The blue curve on the force/displacement diagram
(graph 1) shows how the impact energy is dissipated
without the DIMO® braking system. In the ﬁrst phase
the ring net absorbs a part of the energy. The residual
energy is passed further on in the rope system - bearing,
retaining and anchor ropes, each outﬁtted with brake
strained brake rings, in the second phase the residual
energy is dissipated, mainly through deformation, which
rings. Through the deformation capacity of all of the
leads to an exponentially increasing braking process that
affects and protects the entire system.
Graph 2: Force/displacement with diagram RX-300
with DIMO® braking system
The red curve in the force/displacement diagram
Larger dissipation with the same
displacement distance and the same
(graph 2) shows how the impact energy is dissipated
with the DIMO® braking system. Built-in brake rings,
independent of the rope system, which are strained one
Workdiagram with DIMO®
after the other in the second phase, work in the faster,
stepped way represented in the graph. For rockfall
The same dissipation with a shorter
displacement distance and less load
events with the highest energies these components are
Analogous to graph 1, here also the rope system reacts
with a braking process that protects the system.
built-in intentionally as predetermined breaking points.
OPTUS®: our dimensioning concept
for optimizing economy and acceptable
Our barrier systems are composed of standardized
components. This means that we can provide structures
in any desired length – and, more important, layouts
tailored for the most varied topographical conditions and
risk situations. The model enables us to establish the
applicable fundamental parameters for each design, and
has demonstrated its worth in hundreds of cases.
OPTUS®: the energy diagram as the basis for dimensioning
Energy absorption capacity (kJ)
OPTUS® can help you reach your
The hazard potential and your particular protection needs
determine which energy absorbing capacity protective
structure is necessary. An exhaustive analysis provides
the basis. With commercially available rockfall simulation
programs, it is possible to realistically determine the
necessary design parameters using clearly deﬁned
system as a whole as well as determining the degree
of protection afforded by the system. Here it becomes
evident that the common phrase “less is sometimes
more” also applies to rockfall barriers. For instance,
protective structures with more widely separated posts
achieve a higher energy absorbing capacity because the
structure overall is more ﬂexible.
dimensioning of the individual components and the
Number of rockfalls
The OPTUS® dimensioning concept permits proper
Inspections / emptying
of brake rings
The energy absorbing capacity of a rockfall protection
requirements from the hazard potential, the need for
structure is classiﬁed into three event levels. The
protection, the expected energy and the expected event
basic data for the expected events are provided by
frequency and as a result dimension the rockfall protection
a geotechnical report and a thorough inspection of
the site terrain. We then derive the system protection
Dimensioning with OPTUS® ensures that maintenance
What was included as a “100 year event” in the dimensioning model has occurred; the brake rings – as the last link in
after 90 % of all events will be limited to an inspection
the safety chain – did their job. The system as a whole stood up to the rockfall impact.
and emptying out the nets.
Ring net deformation capacity
Only when the elastic absorption capacity of the ring net
is exceeded do the rings begin to deform plastically.
into the rope brakes.
event, at which point the residual energy is conducted
2) Ring bundles with plastic deformation after a major
rings were not activated.
1) Ring bundles before and after «daily events». Brake
Corrosion protection: only the best is
good enough – because the useful life of
the protection structure depends on it.
Essentially we supply all steel components (posts, ground
GEOBRUGG SUPERCOATING® and hot-dip galvanizing:
plates and brake rings) hot-dip galvanized and the ropes
a comparison after 14 years
as well as ROCCO® rings galvanized with the GEOBRUGG
Both transverse sections were made with an electron microscope after the wires had been exposed to
SUPERCOATING zinc/aluminum coating process. It con-
environmental inﬂuences for over 14 years.
siderably improves the corrosion resistance of the wires
in ropes and ring nets; comparison tests with customary
galvanized wires show that lifespan is extended by a
factor of at least three to four.
The intelligent type of coating
Supercoating (also known as Galfan) is manufactured in
the double-dip process, in which the wires go through
ﬁrst a zinc bath and afterwards a zinc/aluminum bath.
Only in this way can the best possible (eutectic) alloy of
(1) smooth surface (aluminum oxide layer)
(1) heterogeneous surface (zinc), partially complete
5 % aluminum and 95 % zinc be obtained and guaran-
(2) homogeneous coating (zinc/aluminum)
teed. In short: Supercoating combines the advantages of
(3) wire (Fe)
disintegration and/or already with rust formation
(2) hard zinc layer (iron/zinc)
(3) wire (Fe)
zinc (active protection, low cost) and aluminum (smooth
and hard surface, very good adhesion, low rate of
corrosion). After a corrosive assault the smooth surface
In the salt spray test (NaCl) according to DIN
The SO2 test in accordance with DIN 50018 shows an
remains smooth, while the corrosion leads to a decrease
50021-SS/ASTM B117 the Supercoating layer took 3 to
improvement in corrosion protection by a factor of 3 to
in the zinc layer and to the formation of an aluminum
4 times longer than zinc to disintegrate.
4 as compared to customary galvanizing.
oxide layer. The latter leaves a dark gray discoloration
and is the cause for continuing good corrosion protective
behavior, which also gives an economical lifespan in
corrosive environments (roads, railways, industry, coastal
Corrosion protection is optimal for this composition
because of the characteristic nature of the eutectic
mixture (a mixture of very small mixed crystals). At
greater than 5% aluminum, so-called secondary beta
mixed crystals precipitate out, which can lead to the
Residual layer thickness in %
5% aluminum is optimal.
Residual layer thickness in %
and volcanic regions) for the protective structure.
feared intergranular corrosion because of the coarser
granularity. Active corrosion protection decreases with
increasing aluminum content. Scientiﬁc experiments demonstrate that no active corrosion protection remains at
100 200 300 400 500 600 700 800 900 1000
Duration of test in hours
Duration of test in cycles
(Source: Prof. Dr.-Ing. Rolf Nünninghoff)
Installation of the ring net
Cleaning after a number of «daily events»
Where our ROCCO® rockfall struc-
The concept underlying our barriers permits anchorage
Problem-free assembly – whether with mobile crane or
tures lead the others…
and installation in any terrain and with minimal use of
– double bearing ropes on the entire net surface (no
weak areas near the posts and the ground)
– dimensioned for multiple events (successive rockfalls)
– also for falling trees, snow sluffs, falling ice,
– outstanding kinetic properties thanks to high energy
absorbing capacity of the ring nets and brake rings
– The supply of preassembled components, distances
between posts of up to 12m and an installationfriendly net suspension shorten the erection time.
– Our systems are easily installed even in very
irregular topography, because the ring nets adapt to
the contours of the terrain.
– The short braking distance (and thus net deﬂection)
permits installation near the object to be protected
(road, railway tracks). This facilitates installation
(e.g., with mobile cranes) as well as maintenance.
– The dynamic behavior of the ring nets and the
individual rings during impact events reduces
maintenance and repair effort. Single deformed rings
within a ring net segment or whole ring net segments
may easily be replaced.
Because the rings can move freely against each another,
Even when parts of the net are cut out, performance
the net adapts to irregular terrain.
capacity is retained and functionality is ensured.
Systems with energy absorption
capacity from 500 to 5000 kJ.
Geobrugg, a reliable partner…
RX-300 with DIMO® braking concept for 3000 kJ as well as all barrier
It is the task of our engineers (and partners) to analyze
systems with RUNTOP technology for absorbing energies between
the problem together with you in detail and then,
500 and 5000 kJ are certiﬁed in accordance with the Swiss guide-
together with local consultants, to present solutions.
lines for the approval of rockfall protection kits.
Painstaking planning is not the only thing you can expect
from us, however; since we have our own production
plants on three continents, we can offer not only short
delivery paths and times, but also optimal local customer
8 (3000 kJ)
3 (500 kJ)
5 (1000 kJ)
7 (2000 kJ)
9 (5000 kJ)
service. With a view towards a trouble-free execution, we
ROCCO® ring net type
deliver preassembled and clearly identiﬁed system
components right to the construction site. There we
provide support, if desired, including technical support –
Post type min.
from installation right on up until acceptance of the
Post type max.
Distance between posts
8 to 12 m
6 to 12 m
6 to 12 m
8 to 12 m
8 to 12 m
Rope diameter min.
About “product liability”
Rope diameter max.
Rockfall, slides, mudﬂows and avalanches are natural
Per 60 meters structure length:
events and therefore cannot be calculated. This is why it
Number of brake rings in support rope
is impossible to determine or guarantee absolute safety
Number of brake rings in retaining rope
for persons and property with scientiﬁc methods. This
Structure height min.*
means that to provide the protection we strive for, it is
Structure height max.*
imperative to maintain and service protective systems
max. displacement distance**
regularly and appropriately. Moreover, the degree of
min. residual useful height impact section**
protection can be diminished by events that exceed the
min. residual useful height adjacent section
absorption capacity of the system as calculated to good
max. lateral anchor load**
engineering practice, failure to use original parts or
max. mountain side anchor load**
corrosion (i.e., from environmental pollution or other
* according to Swiss guideline **according to type test
DIMO® can also be retroﬁtted!
With the DIMO® brake system you can also increase the protective effect and performance of existing Geobrugg RX
rockfall structures – for example from 1500 to 2000 kJ or from 2000 to 2500 kJ. We will be happy to give you a
For protection needs with impact energies between 500 and 5000 kJ see publications respective. Right to technical
Fatzer AG • Geobrugg Protection Systems
Hofstrasse 55 • CH-8590 Romanshorn
Phone +41 71 466 81 55 • Fax +41 71 466 81 50
www.geobrugg.com • [email protected]
A company of the Group BRUGG
Certiﬁed in accordance with ISO 9001