Just when I thought NO sane conversation could be made about “Doon”, something came up that is of interest in an engineering sense. I will have to modify the question to include RAILROAD interest. Forget about the derailment at Doon (for the moment, or better yet, forever, IMHO)
Using the same logic quoted/discussed below, if a cantilever bridge is being used as a trestle on a railroad, and a load in the middle of the structure were to exceed the weight limit ………………liquification is the cause of failure???
As I understand it in physics/materials there is stress, strain, elastic modulus, etcetera. In the discussion BELOW a statement was made that caused me to wonder and seek explanation.
reference: Partial post of by VOLKER LANDWEHR Tuesday, July 24, 2018 8:28 AM/ with replies
…………………MY emphasis is highlighted by bolding text(mrw)
Somehow you mixed up. What you say is my quote is from dhusman. Here is my complete post again
"dehusman Volker: Metaphors for what we are talking about. You have a beam that centilevers from a wall. You drop a load on it and the beam shears off and the load falls to the ground. That’s a slope failure. You have a beam that centilevers from a wall. You drop a load on it and the beam deforms and bends, the load falls to the ground. That’s liquifaction."
First, no need to explain the difference between liquifaction and landslide to me. As I said before I’m a civil engineer and that means I learned at least the fundamentals in soil mechanics and geotechnic before specializing in structural design, where these fundamentals are needed too.
When you make comparisons you should do it right. A cantilever beam usualy has a stress failure caused by the bending moment not a shear failure. Brackets experience shear failure.
dehusman One is a shear failure, the other is a deformation.
Wrong, both are shear failures only with different consequences.
My comment to your post:
In his post dhusman tried to explain to the difference between slope failure and soil liquifaction in terms of structural systems.
I have been holding my tongue about evolving … discussions … in this thread. But I draw the line at folks who don’t know how to run the quote function and then comment snarkily about what are basically their own misquotes. (Thanks, Volker, for trying to answer it objectively. Hope it does some good.)
This is not quite as pathetic as the comments about sourcing the information for “Do You Live In The Blast Zone”, but you can see it from there.
C’mon guys, you can have a better level of discourse, even if you still have trouble spelling ‘liquefaction’ after all these posts.
Mike, by the time you got done with that whatever-it-was-you-were-trying-to-establish, even I couldn’t figure out what if anything you were trying to say. Except that by back-translating some of those bolded comments you thought it was inappropriate to say that steel was prone to suffer liquefaction, or something.
That’s the gist of the criticism, not that professionals are picking on your homespun wisdom somehow. In my opinion some of the metaphors being used are worse than any confusion in the original, and that seems to be one of the points you meant to make, but until I can comprehend your actual arguments better I’m not sure what the issues of concern to you are.
The chief difficulty Euclid has with liquefaction is that he assumes that when the phenomenon occurs, as in quicksand, there is no permanent displacement of the mass of fluidized soil when the load is imposed. I think there may be an analogy to what occurs in ballast contamination with fines followed by pumping, where there is a lack of integrity in the subgrade under the track that is masked by a tendency for the track to hold apparent line when unloaded. I would think that recourse to train-generated vibration inducing a state of liquefaction in the subgrade under good ballast is more than a little bit of a stretch; at the very least you’d see signs of incursion of the fluidized subgrade in, probably coating, the ballast, and at least some of the ballast aggregate being forced down and kept after the liquefying vibration had passed off.
And yes, I’d think lateral distortion due to ‘shear’ failure in some plane in the subgrade would be more likely a cause of track-geometry ‘compromise’ leading to derailment than vertical liquefaction driven by train vibration would be … but that&#
What gives you the idea that I assume that when the phenomenon [liquefaction] occurs, as in quicksand, there is no permanent displacement of the mass of fluidized soil when the load is imposed?
I don’t know if liquefaction requires vibration, but it seems well documented that vibration can be essential in producing liquefaction. When vibration produces liquefaction, it does result in a shear failure of the soil, but if it were not for the vibration, there would be no liquefaction and thus no shear failure (in at least some cases). So I don’t understand why you seem to rule out vibration and replace it with shear failure.
I suspect that liquefaction failure at Doon may have developed with the passage of other trains preceding the one that derailed, and if that is so, I would expect that some of the evidence you cite may well have
The most accurate part of the above is “I don’t know”. Most of us when we don’t know prefer not to display our ignorance. Why not go to university and take some soil mechanics and geotechnical courses, and then come back with more intelligent speculation. I learnt enough working with experts that I can recognize garbage when I see it. I could re-enter the conversation but that would only provide more material for you to misuse.
I’m always surprised how easily people pick on Euclid’s post just because he is Euclid but not willing to contribute anything and hide behind excuses. If someone acuses someone else of writing garbage he should proof/explain it. Otherwise I can’t take this person seriously.
I find it totally okay that someone offers an opinion though he is not sure of all detail or even might have some wrong. No better way to learn if others help out. That is one of the reason for discussions
To Euclid’s uncertainty: Soil liquefaction needs vibrations.
Usually, behavior such as that has some basis in past experience. I don’t think anyone has picked on Bucky just because he’s Bucky. He’s established a reputation.
And this has been a part of the issue in the past. Bucky offers an opinion which is factually incorrect, then bases further conclusions on that opinion as though it was fact. If called on the mistaken conclusion, “yes, but.”
And yes, I have cited specifics when countering his mistaken conclusions in the past. Maybe that’s why he’s a little more thorough these days.
You know, I was going to reply to that, but it’s not worth it.
If I was the only one questioning your posts, I might agree, but that’s not the case. I’ve been purposely staying out of most of the latest conversations.
The ‘shear failure’ is subsequent to the liquefaction action, no matter how generated, and while it might be taken as the ‘proximate cause’ of the actual derailment there are alternative methods of inducing a shear failure that do not involve the specific physics observed for liquefaction. Let me slam the door on any line of argument or discussion that equates “vibration” and “shear failure” here.
Now, in order to produce liquefaction, you need a motion of water sufficient to fluidize an appreciable volume of soil for a considerable time under a train’s weight. A very likely component of force to produce such motion would be vibration, and a good engineer can calculate frequency ranges for a given grade or subgrade that would be most efficient at producing it and compare those to actual vibration characteristics produced by an oil-train consist. The argument, however, is slightly different: would liquefaction producing purely a vertical displacement of the track result in a derailment? I find this relatively unlikely based in part of my knowledge of the dynamic response of three-piece trucks and the experience of the Army demolitions people investigating the best ways to derail trains in WWII. This is not to dismiss the idea that liquefaction is related in some way to the incident, only to note that concluding liquefaction IS either the expedient cause or a major contributor to the incident is at best premature.
Possibilities do, I think, include the idea of liquefaction-related settlement under one ‘side’ of the train, or (as noted) lateral slip of some part of the gr
I think he got a reputation attached. By the way a repution is not more than a facade. Only when you see what backs a reputation you can judge it. And there lies a problem some have with Euclid. He doesn’t give his credentials and that seems to unsettle some.
Many here believe that only experts can be right and that is pure nonsense. Instead of checking what he says, and he often supports his opinions with citations, some react as if everything must be wrong, him not being an expert. Reading thinks? Why, facts could come into the way of preocupation.
[quote user=“tree68”]
VOLKER LANDWEHR
I find it totally okay that someone offers an opinion though he is not sure of all detail or even might have some wrong.
And this has been a part of the issue in the past. Bucky offers an opinion which is factually incorrect, then bases further conclusions on that opinion as thoug
For me liquefaction is one possible cause among a lot others. In contrast to Euclid I haven’t made up my mind because of too few information. I tried to keep the discussion on a factual level.
Regards, Volker
Based on what I remember from the Sheriff’s video, the first 7 cars stayed on the rails and stopped on the south side of 270th Street. The next two cars were derailed on the west side of the r-o-w, roughly parallel to it, just south of the main pileup of 30 (or so) cars.
So, it appears that either the 9th or 10th car was the first to derail.
I’m far less concerned with a “wrong” opinion than I am a misconception presented as fact. For instance, yellow diamond traffic warning signs don’t “take effect” like black and white traffic regulation signs do. In fact, they effectively have a “halo” of some 600 feet before the sign that the MUCTD considers as part of the distance for placing such signs to effectively warn of an upcoming condition.
My concern in the first Doon thread was the implication that the crew should have slowed down simply because the water level was judged to be high by a poster here. My entire point was that up until the crew actually saw the water was as high as it was (at 0430, in the dark), they had no reason to do so, as it appeared the railroad itself was not concerned.
Why the railroad was not concerned is a question in and of itself, as has also been discussed.
My train of thought continued right through the introduction of Rule 6.21 to the discussion, as it was never established that any of the conditions in the rule were met prior to the derailment. Again, the railroad apparently didn’t feel the water level was a problem or they would have issued directives to that effect. To our kn
