As a member of the organizing committee, I welcome all interested on rockfall at the Rocex 2014 in Lecco - IT
Phone call from a blast:
Hello Thomas I'm Giacomo and on 21 January, a large rockfall occurred about 3000 cubic meters and impact a farm nearst of Bolzano in South Tirol -IT.
On the cliffs in high above the farm was (in precarious balance) a large pillar of about 500-600 cubic meters.
On January 22, we carried out flight with helicopter to verify the situation with the geologists of the Geological Survey of Bolzano and we approved the demolition plan.
In terms of urgency we have obtained licenses for explosives in a single day.
The dimension of pillar was:height of about 14m; width 10.5m and thickness 3.5 m; the base of the pillar was compromised and therefore it was decided to break up it to avoid the fall of large volumes .
The day 23 was prepared the site at the top of pillar with scalig operation and at the same time the climbing company has started to develop holes for blasting. Since the instable volume was big we decide for small diameter holes (51mm) made with portable drilling machine and depth of 4 m .
The day 24 was performed the first blast which was conducted with a strong overdose of the explosive in order to compensate for the small drilling that in some points appeared deficient for obvious safety problems (to limit the vibrations). Around the zone was made a security fence guarded by about 50 volunteer firefighters groups of Termeno (BZ) of about 400 m from the blasting point; at he end of slope we have realize a rockfall earth dam for protection of a pylon of high voltage ( interrupted at the time of the blasting ) and the farm .
The demolition was then completed on January 27; after the first blasting we could get with more security at the bottom of pillar for load the last part of blast and explosion.
This is all...in next days will send to you some video of events
Thank you Giacomo
By - By Thomas
Large scale video
Detail scale video
From the experiences in submarine environment, this technology from Maccaferri could be applied to protect against natural risk in mountain?
In many cases the pipeline (water, sewers, it cable, ets..) pass nears rock slopes with rockfall problem; in some cases for my point of view this solution could be applied with a little layer of covering granular materiel (only aesthetic).
Thank you to John D Duffy from DOT of California (USA) for this interesting news. The book published form Transportation Research Board (TRB).
I attended in october 2012 the full scale test organized by Maccaferri Spa and Risp Srl in the field test facility of Fonzaso - IT.
The test on rockfall barrier (RMC P650) with 6500kJ energies, post height 6.5m, impacted by boulder of 17666kg dropped from a height of 38.25m.
The video beolwe granted from Risp Srl, describe the event.
In the last 10 years I have seen a lot of 1:1 test on rockfall barriers but this was impressive for two reasons:
My point of view regarding the symmetric behavior is due to large number of brakes elements (with short eleongation, aprx 1.0m, ) distributed on the structure RMC P650 that guarantees an optimal distribution on forces in space and time of deceleration.
The bounce of boulder indicates (for my opinion) that rockfall barriers still has many structurals reserves....this is positive because the technical limits on rockfall barriers must and can still be reached.....good work to the producers...
What do you think?
I was invited by Geobrugg to attend a revolutionary test 1:1 in Winterthur (CH) October 9, 2012. It was a full-scale test to verify/ceck the behavior of the flexible steel mesh on a platform that simulates a slope landslide. Video procedure are linked belowe.
I seem to be back at the beginning of 90’s with the first full scale tests on rockfall barriers organized form Tubosider in France, Igor in Italy and Geobrugg in Switzerland. After 20 years of test 1:1 on rockfall barrier could be organize a “Technical Guideline to 1:1 test on felxible nettings” to standardize the procedure to test in full scale the nettngs on slops? What do you think?? Thomas
In many cases the rockfall protection barriers must adapt to the conditions of the terrein. One of the points that require greater attention and detail to guarantee the structural strength of the rock barriers is te deviation on lower lateral cable. In the drawing belowe you can see two typical case but not the only one. You may need to resolve deviations elevation (as in drawings) and planimetric.
Case n°1: lateral lower cable deviation
Case n°2: intermediate lower cable deviation
....after the Guideline ETAG027/2008, the variation of geometry of the rockfall barriers respect to the tested barrier will be guaranteed by the manufacturer with special calculation as as described in chapter 4.3:
"If for local reasons of the natural site it is necessary to have a different geometry from the test site geometry a specific design shall be provided. Forces acting in the structure should be evaluated to demonstrate the fitness for use of the falling rock protection kit. The producer, under its own responsibility, shall provide geometric tolerances in the installation book with special references to the spacing of the posts and the inclination of the main ropes".
I don't understand if the responsibility to define what forces act on the modified structure are in charge of the manufacturer or designer???
And today for my experiences I've never found a manual with described tolerances permitted for the deviation of lower/lateral cable.
Who can clarify this issue?
In last years, expecially in United States and Canada a new type of rockfall protection system has developed.
These new barrier are usually called "rockfall attenuator" or "hybrid barrier". The reason for these two definition are:
For my point of view is better the terms "attenuator barrier" is a more intuitive terms to explain the behavior of structure.
Where the zone to protect has before a sufficent area of possible accumulation of block, the AB (attenuator barrier) will be interesting; with this system the block are not stopped but guiding down along the slops and accumulated at the foot of slops. Another interesting aspect of this barrier is the reduction of maintenance and the capacity of auto cleaning.
In this drawings belowe are be explained the behavior.
Here you can find some detail directly from the web:
Others contributors will be appreciated
l giorno 30 Novembre 2012 a partire dalle ore 14:00 a Bolzano avrà luogo a Bolzano il "Primo Incontro delle Commissioni in Ingegneria Geotecnica degli Ordini degli Ingegneri".
L'evento è patrocinato da AGI e CNI.
Recently news on high energies rockfall protection barrier has opened a discussion on the energy lmitis of the rockfall protection steel barrier.
Many people have asked me this: is a 8000kJ barrier equal to two allignment of 4000kJ barriers when impacted from the same block?? (see the image belowe).
The answer is very difficult and dipending to differnet factors.
To try answer I make before some considerations (we refer for example to ETAG027 guideline procedure testing):
For this reasons, if the impact energy is greater than the MEL Energy of the barrier, we can't say that (see drawing belowe):
For this reason my firs answer is that 4000kJ+4000kJ is different than 8000kJ in terms of behavior of structure..... but I don't know if 4000kJ+4000kJ is greater or lesser than 8000kJ.
In a next post I try to find a model to calculate the energy exit of the rockfall barriers (E-out) and try to answer to the question.
Discussion open !!!
Until now, the protection systems against rockfall for high energies (greater than 5000kJ) were rockfall embackments with or without geogrid and rockfall galleries ..... will not be as ... a new system of rockfall barrier in steel insert in this level of protection energy. The 8000kJ height 8.5m barrier of Geobrugg AG has achieved a new record.... congratualtion to all the staff of Geobrugg AG for this interesting news...