TycoPicard,
Thanks - I logged on to PPRUNE because I had just got an e-mail with these photos, and I saw your post.
I also wonder if it was a test or what the story was. Those are some skid marks if just from turning. The kinetic energy or energy of motion is dissipated between the tyres and the surfacing in the form of heat and it is this heat that dissolves, or melts, the bitumen and oils on the asphalt surface, thus creating the distinctive dark smear commonly referred to as a tyre mark, or in this case, a skid mark. Although some small particles of tyre rubber do separate from the tyre itself, the skid mark is primarily composed of bitumen. That must have been a heck of a kinetic energy level to make those marks. Still, looking at the tyre distortion (and someone in the other thread suggested the leg was bent), there is a lot of energy there.
Clearly the top of the surfacing has been torn. A computer enhanced version of one of the photographs is at
http://www.kubu.net/A380_turn.jpg and you can see loose asphalt lying on the surface. Zoom in closely, (a large photo zoomed in is at
http://www.kubu.net/A380_zoom.jpg) and you can see that the asphalt is being screwed out by only the (outer?) closest two tyres of the bogie. You can see one of the inside (?) tyres of the bogie and there seems to be no loose asphalt under the tyre.
The distortion of the outer tyres shown in the other photos in the other thread means that much more of the load is being taken by the one sidewall (on the inner side of the outer tyres) - pushing the asphalt out. Add to this the non-uniform distribution of stress under a tyre and the result is a very substantial increase in stress under that sidewall. Based on Morris and Emile's work, I would estimate vertical stress as high as 2800 kPa.
The sideways force on a skidding tyre depends on the coefficient of friction of the asphalt, and for new (little trafficked) dry asphalt, 0.8-1.2 is a typical range. Let's take 1.0. That gives a horizontal force per A380 tyre at MTOW of 300 kN. The horizontal stress pushing the asphalt out in front of the skidding tyre is being resisted not by the whole tyre footprint but a smaller effective area, and the horizontal shear stress is now 5952 - call it 6000 kPa at the surface of a 125mm thick asphalt layer. Much higher than under braking.
The maximum air temperature at Toulouse on 25/6/05 was 33 oC (if it was Toulouse); and converting that the surfacing temperature is imprecise but 60-65 oC would be a reasonable estimate. I guess that the torsional shear strength of that asphalt at that temperature and presumably at the low aircraft speed, was a bit below 6000 kPa (and I would think it not unreasonable to be so). It failed.
I look forward to learning more about the incident. If this is part of normal ops and is not some sort of test, then it's potentially got implications for airports with the A380 operating on asphalt in summer temperatures. And also for those airports that have just finished building their taxiway fillets, widening corners, and all the other works to accommodate the A380, and who used the sharp (but allowable) steering angles in their design, well this might indicate some problems. Or maybe the photos are just part of some extreme test. I sketched out the geometry of the turning aircraft and I can't see how the bogie can be skidding sideways. It's more like a minimum width runway test, with the aircraft ending up sideways. Or my wife driving. Anyway I suspect the Airbus pavement engineers will be working hard on this one, and I think I've given them the answer above. Donations in the form of Moet gratefully accepted - say a bottle per kN.