How simulation can help solve cold cases
The history
On June 25, 1967, a serious attack took place on the Porzescharte, a high alpine border pass between East Tyrol (Austria) and Cadore in the Italian province of Belluno. Four Italian soldiers were killed by explosives attack. The Italian government blamed members of the South Tyrol Liberation Committee - an organization that campaigned for South Tyrol's independence from the Italian state. According to the official account, the perpetrators are said to have climbed up from Austria via the Obertilliach Valley to lay several booby traps on Italian territory.
The central component of the operation was the blowing up of the 220KV electricity pylon no. 119 of the Lienz-Pelos high-voltage line. This was located directly on the national border and was severely damaged by a blast. Only a few hours after the blast, an Italian mountain infantryman (Alpino) entered the area to investigate the incident and stepped on a mine - he died of his injuries. A subsequent special forces team of 4 soldiers, consisting of paratroopers and deminers, also stepped on a mine. Three more soldiers died and a fourth was seriously injured.
The exact course of events has not been fully clarified to this day and is extremely mysterious. While Italy considered South Tyrolean activists to be responsible - Peter Kienesberger, Erhard Hartung and Egon Kufner, among others, were named - Austrian historians such as Hubert Speckner cast doubt on this version. According to his research, there are considerable inconsistencies in the chronological sequence, the route and the actual sequence of events, as well as massive contradictions in the execution of the blasting of the mast and the explosion of the mine in Karrenweg. It is also being discussed whether the incident may have been deliberately instrumentalized by the Italian side for political purposes.
The attack led to a serious diplomatic crisis between Austria and Italy and is considered one of the most dramatic incidents of the South Tyrol conflict. At the time, Foreign Minister Lujo Tončić-Sorinj spoke of the lowest point in bilateral relations since the end of the Second World War.
This would at least partially answer why a reappraisal of the case is of great interest. However, we are primarily interested in the technical aspects, the scientific reconstruction of the mast blast in detail.
The task
Prof. Dr. Ing. Harald Hasler MSc MA, as a court-certified expert for explosives, blasting technology, mines and forensics, carried out extensive scientific field tests and experiments as well as the most precise reconstructions with various explosives, which are described in detail in his book Wissenschaftliche Neubeurteilung der Rechtssache “Porzescharte 25. Juni 1967” (see link below).
This revealed massive contradictions which made it clear that the events could hardly have happened as described in the court documents. A central point: the alleged demolition of the 220KV electricity pylon no. 119 on record, with only one detonation of the 4 corner pillars, carried out in a night-and-fog operation without light and under the constant threat of being recognized.
A 1:1 field test with a physical demolition of an exact replica of the pylon as on site on the Porzescharte would have been absolutely impossible and would have blown the budget - in the truest sense of the word. Our task was therefore to realistically simulate the behavior of the electricity pylon during and after a demolition of the 4 corner pillars using the finite element method (FEM) and to illustrate the effects. The aim was to investigate how the structure behaves under its own weight after the targeted destruction of the 4 individual corner pillars carrying the load. The simulation should clarify whether and how the mast fails as a result of two successive blasts, how it behaves and finally tilts completely on the ground and comes to rest.
Results of the simulation
The investigation revealed that the electricity pylon initially retained its structural integrity after the first targeted blast. Although parts of the truss structure were severed, the pylon's own movement quickly caused contact at the interfaces, which prevented complete failure. The mast only performed oscillating movements, but remained stable overall. The design of the mast bases with the corner posts, the structure of the truss and the cable bracing played a decisive role here.
It was not until a second blast that a decisive structural failure occurred. Among other things, the western foot of the pylon was completely severed, which meant that it could no longer absorb any compressive forces. As a result, the entire structure tilted in a north-westerly direction. The resulting tilting moment significantly exceeded the remaining load-bearing capacity of the pylon, which led to plastic deformation and ultimately to the collapse of the entire structure.
In an extended simulation, the complete tilting of the mast down to the ground could finally be represented realistically. Previously occurring numerical instabilities were successfully eliminated by finer modeling with shell elements. The results of the investigation support the assumption that a two-stage blasting process was necessary to bring about the complete cause the mast to fall over.
So that you can experience the numerical “act of terror” live, we have included an accompanying video of the simulation:
And what happens next?
Prof. Hasler can use our numerical simulation as clear evidence and a basis for his expert opinion on the matter and build his expert opinion on it. This shows how valuable the finite element method (FEM) is and what possibilities it offers.
Now that we have acquired a taste for each other - we are working on the field tests and Prof. Hasler on our numerical simulations - we are tackling new topics together, as there is a lot to do here. The demolition of a building is being simulated numerically in a very complex way. This simulation is the historical explosives attack from the same period, on the STEINALM on the Brenner Pass. The simulation can generate very valuable findings for the structural behavior of the building and for the coordination of further field tests with dummies and reconstruction explosions. If experiment and simulation interact skillfully and complement each other, many variants can be investigated much more efficiently and safely than with a pure test or simulation operation. The level of information about reality is significantly higher and more accurate. In explosive engineering, precisely this approach is possible today and therefore very precise.
If you have similar tasks - even if they are not related to criminal cases - we look forward to hearing from you. As always, feedback on my blog articles is also welcome. If you have any current topics that you would like to find out more about, let me know!
PS: If you want to read the complete expert opinion, you can order the book here:
The website of Prof. Dr. Ing. Harald Hasler is:
www.harald-hasler.at
Yours Stefan Merkle
