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)
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...... ( say what ????? that is a Volker quote MRW) 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. (Okay, if you insist, but I fail to see how the word liquefaction can be used since there is NO liquid involved. All items in the beam scenario are solids..............…albeit “solid ground’ can be made into particulate matter and “act” like a liquid. But a true solid like steel cannot flow like a liquid unless heated and truly become liquid.The “beam” describe above is surely made of something more “solid” than soil or ballast…..MRW)
dehusman
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.
One is a shear failure, the other is a deformation.
VOLKER Wrong, both are shear failures only with different consequences.
COMMENTS, ANYONE? THANKS MIKE ENDMRW0725180015
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."
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.
Slope failure: http://dkgeo.de/Bild/boeschungsbruch.jpg
It is in German but self-explanatory.
Results of soil liquifaction: https://www.researchgate.net/profile/Sayed_Ahmed11/publication/288515983/figure/fig9/AS:319868416086025@1453273981382/Failure-of-apartment-buildings-by-tilting-in-Niigata-due-to-liquefaction-Source.png
Very simplyfied, how good a soil withstands forces depends on the interlocking of the single grains, their compaction and, in case of cohesive soil, cohesion. One indicator is shear resistance.
When a slope failure occurs, a load on top might lead to shear forces in the soil exceeding the shear resistance. Other reasons can be too steep slope, too high slope, vibration.
With soil liquifaction under special soil and water condition vibrations can lead to a shear resistance reduction to zero. Now the soil reacts like a fluid and e.g. buildings loose the resistance under their foundation.
In both cases we have a shear failure, though with different causes and consequences.
Here is a nice picture how liquifaction can lead to slope failure. Though funny looking it is right: https://slideplayer.com/slide/7951733/25/images/13/IMPORTANT%20CONCEPTS%20INTERNAL%20CAUSES%20OF%20SLOPE%20FAILURE%20Quick%20sand.jpg
I hope that helps. Otherwise ask, please.Regards, Volker
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.
OvermodC'mon guys, you can have a better level of discourse, even if you still have trouble spelling 'liquefaction' after all these posts.
I'll try to remember Regards, Volker
OvermodC'mon guys.......... you still have trouble spelling 'liquefaction' after all these posts.
Thanks to Chris / CopCarSS for my avatar.
Overmod 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.
You professional posters win. This is not the first time my novice ways have been offensive. Sorry for the angst caused.
I am now "bad order" sitting on a siding and watching you professionals highball on the main. over and out mike endmrw0725181323
Cotton Belt MP104I am now "bad order" sitting on a siding and watching you professionals highball on the main. over and out
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's completely unproven by any available evidence I've seen, and in fact contradicted by the speed with which this derailment appears to have been ameliorated. Which is why I've said little, and continue reticent until better informed.
OvermodThe 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 ...
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 been visible, but went undetected by the inspections.
EuclidWhat 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 been visible, but went undetected by the inspections.
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.
For all I post a link to the website of the Institute of Geotechnical Engineering at the Technical University Dresden Germany with an explanition what happens inside the soil during liquefaction: https://tu-dresden.de/bu/bauingenieurwesen/geotechnik/forschung/forschungsfelder/bodenverfluessigung?set_language=de
Though there is a link to change to English this is not available. I tried to translate it:
cx500 ..I learnt enough working with experts that I can recognize garbage when I see it. ...
..I learnt enough working with experts that I can recognize garbage when I see it. ...
I would bet your mentors were more patient and kindly disposed toward instruction and enlightenment, and less inclined to harsh ridicule, than you.
VOLKER LANDWEHRI'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.
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.
VOLKER LANDWEHRI 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 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.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
tree68 VOLKER LANDWEHR 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. 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. 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 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.
VOLKER LANDWEHR 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.
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.
Oh yeah, and you wish I had established a reputation, since you seem to always be working hard at contributing to it.
And of course you are somehow anointed to be always the one who gets to decide what is factually incorrect.
What you have stated above about me is entirely your made up narrative of generalizations that nobody can verify. How convenient for you. It is nothing but your gossipy personal attack because you just can’t stand the fact that I have the audacity to disagree with you at times. And that is exactly what you express in your childish “yes but” barb. The “but” is the part where I disagree with you and that is just not acceptable in your little world. I think you’d be surprised at how many people can see through what you are up to.
Euclid I think you’d be surprised at how many people can see though what you are up to.
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.
tree68 Euclid I think you’d be surprised at how many people can see through what you are up to. 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.
Euclid I think you’d be surprised at how many people can see through what you are up to.
EuclidWhen 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.
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 grade/subgrade resulting in impairment of track geometry. I would note that neither of these, if they were present, seem impossible of remediation within the timeframe and apparent resource allocation BNSF provided after the incident; it would be interesting to hear mudchicken's analysis of the situation if he is inclined to comment based on what information we know.
Has it been established where the actual point of derailment in the consist was?
tree68 VOLKER LANDWEHR 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. 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.
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.
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 though it was fact. If called on the mistaken conclusion, "yes, but."
In the early stages of a thread the "yes, but" is what he explains in his post. The "but" can mean disagreement or asking for clarification. If it gets repetitive I leave the thread.
Euclid should learn to recognize when he can't convince anybody anymore in thread and stop his repetitions.
When he offers a, in your view wrong, opinion, and is called, I find it only natural to try to back it up. There is a difference between some here and Euclid and e.g. me. We don't naturally believe experts. I had to clean up a number mistakes of so called experts that tend to question them.
Going in these discussions/speculations open minded and nonbiased would help a lot.
The first Doon thread is a good example for another phenomenon. When railroads are questioned the circle-the-wagons mentality comes through regardless of fact. The conclusions I drew might have been wrong but by ignoring the facts some provoke the "yes,but".
A last point, you blamed for covering the bases. What do you think what NTSC does? They go through the evidence and make a long list of possible causes. Cause by cause is checked against the evidence to eliminated causes. Often you need further investigations and sometime you need to get back to a cause you thought you eliminated already.
So covering the bases is a natural process in accident investigation.Regards, Volker
Overmod Let me slam the door on any line of argument or discussion that equates "vibration" and "shear failure" here.
It is not an equation but vibrations can cause slope failures if shear resistance is exceeded.
OvermodThe 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.
I think that depends on how the track deforms. But as you said the liquefaction isn't necessarily centric under the fill. Here is a picture I first found in an German University publication identifying the cause of the slope failure as liquefaction through an earthquake (Seattle, 1965): https://upload.wikimedia.org/wikipedia/commons/thumb/f/fb/1965_Seattle_EQ_damage.tif/lossy-page1-1000px-1965_Seattle_EQ_damage.tif.jpg
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
Overmod
VOLKER LANDWEHRA last point, you blamed for covering the bases
VOLKER LANDWEHRWhen he offers a, in your view wrong, opinion, and is called, I find it only natural to try to back it up.
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 knowledge, that was not done.
Even now, as has been mentioned, it has not been established (to our knowledge) that the water level was even a factor. The asteroid idea is a little facetious, but a broken wheel/axle/bearing is not out of the question. It occurs to me that an overheated bearing suddenly being cooled might be problematic.
OTOH, unless the head end backed up, the fact that they travelled only as far as they did after the derailment suggests that they had already reduced speed, for whatever reason.
VOLKER LANDWEHRMany here believe that only experts can be right and that is pure nonsense.
Yes, and also pure nonsense that anyone who claims to be an expert is one.
OvermodHas it been established where the actual point of derailment in the consist was?
A key point, particularly if the cause was mechanical, as the train may have derailed a distance of several cars before one of them dug in and stopped, causing the rest of the pile-up.
tree68 I'm far less concerned with a "wrong" opinion than I am a misconception presented as fact. 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 knowledge, that was not done. Even now, as has been mentioned, it has not been established (to our knowledge) that the water level was even a factor. The asteroid idea is a little facetious, but a broken wheel/axle/bearing is not out of the question. It occurs to me that an overheated bearing suddenly being cooled might be problematic. OTOH, unless the head end backed up, the fact that they travelled only as far as they did after the derailment suggests that they had already reduced speed, for whatever reason.
I'm far less concerned with a "wrong" opinion than I am a misconception presented as fact.
You say I presented an opinion that you know to be a misconception. If you believe that I am presenting an opinion, how can you claim I am presenting it as a fact? Even if my opinion is wrong, I have the right to believe that it is correct. Yet you seem to regard that as some type of injustice that you have the right to publically accuse me of. We get to have opinions.
And then you go on to state all of your opinions about why my opinion about the Doon wreck is wrong and how it is unjust for me to state it. You have no problem with all of your opinions because you consider them to be facts.
You say that the crew had to see the water before they could be expected to slow down. How do you know they did not see the water? What if they did see the water and did not slow down? You say it appears that the railroad was not concerned about the high water. How do you know that the apparent lack of concern means that the company was justified in not requiring the crew to slow down? What if the railroad misjudged the need to slow down? What if they should have issued directives to slow down, but failed to do that? What if they did issue directives, and the crew failed to comply with them? What if the directives were inadequate?
Your set of refutations of my opinion is just as much opinion-based as my opinion. And yet you feel that it is wrong for me to offer my opinion.
tree68My 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.
I was the poster you mention here. And I presented the facts as they were available to the public, sic also to BNSF. But one needs to open the links and read them.
Neither Euclid nor me said the railroaders needed to slow down (on sight). I said that BNSF should have issued a speed restriction.
tree68Why the railroad was not concerned is a question in and of itself, as has also been discussed.
It has been discussed but never really answered. Some here even negated that it was an unusual high highwater, though there was the desaster declaration by the state of Iowa. So we disagree on the question is Rule 6.21 applicable or not. And here the circle-the-wagons mentality came into play.
tree68Again, the railroad apparently didn't feel the water level was a problem or they would have issued directives to that effect. To our knowledge, that was not done.
That doesn't naturally mean BNSF was right in its decision. If there was an accident one needs to question all decisions that might have led to it. Defending is not the way to go.
tree68Even now, as has been mentioned, it has not been established (to our knowledge) that the water level was even a factor. The asteroid idea is a little facetious, but a broken wheel/axle/bearing is not out of the question. It occurs to me that an overheated bearing suddenly being cooled might be problematic.
Euclid and me have both acknowledged that there are a lot of possible causes. Euclid came to his conclusion that liquefaction was the cause. I think it would have been appropriate for BNSF to issue a speed restriction based on rule 6.21. I haven't made up my mind regarding the causes. In the case of liquefaction I tried to help with facts.
tree68OTOH, unless the head end backed up, the fact that they travelled only as far as they did after the derailment suggests that they had already reduced speed, for whatever reason.
Looking at the pile-up of the tank cars I doubt it.
tree68 VOLKER LANDWEHR A last point, you blamed for covering the bases Huh?
Sorry, the sentence read as follows: A last point, you blamed Euclid for covering the bases.
Your post and my answer all are opinions. Some opinions are backed by facts others perhaps not. So where is the problem? Perhaps that we started to blame a railroad? Please, think about it.Regards, Volker
EuclidYou say I presented an opinion that you know to be a misconception.
No - an opinion is just that - a person's view of something. A misconception is an erroneous belief that something is the case, when in fact is isn't. See my example of the warning sign. It should look familiar.
EuclidAnd then you go on to state all of your opinions about why my opinion about the Doon wreck is wrong and how it is unjust for me to state it. You have no problem with all of your opinions because you consider them to be facts.
Never said your opinions are wrong - only that there are often other factors to consider. And my opinions are just that, opinions. You're the one casting them as facts. If I'm going to present something as fact, I'll back it up, as I did with the river levels.
There are things I'm an expert on, things I'm simply knowledgable about, and things I'm just John Q Public on. Just like everybody else.
As for your other questions - I don't know, which is why the word "apparently" appears so often in my posts. My conclusions are based on what I've seen and our discussions here. If those conclusions are proven to be wrong - so be it. We'd all love to see the information that would make such a judgment possible, although, as discussed, we probably never will.
RDG467So, it appears that either the 9th or 10th car was the first to derail.
That early in the train suggests the simple liquefaction scenario is unlikely. It takes time for the vibrations to do their worst, and on an important main line with good ballast, surface and CWR the vibration is much reduced.
Under the right conditions there is not much vibration over long times necessary. Here is a laboratory video from RWTH Aachen, a German technical university showing the process: https://www.youtube.com/watch?v=ZMWKTuRgJjY
I'm not saying liquefaction was the cause but I in my opinion it shouldn't be ruled out.Regards, Volker
VOLKER LANDWEHR Under the right conditions there is not much vibration over long times necessary. Here is a laboratory video from RWTH Aachen, a German technical university showing the process: https://www.youtube.com/watch?v=ZMWKTuRgJjY I'm not saying liquefaction was the cause but I in my opinion it shouldn't be ruled out.Regards, Volker
Interesting video. I believe you'd agree that this is not *completely* representative of real life, because the structures on the table did not have any foundations, they merely sat on the soil's surface.
Plus, the shaking force was parallel to the ground surface, not perpendicular, as would occur under the relatively low-frequency cyclical loading of a unit oil train. Which is mostly absorbed by the wooden ties and ballast anyhow.
RDG467Interesting video. I believe you'd agree that this is not *completely* representative of real life, because the structures on the table did not have any foundations, they merely sat on the soil's surface.
Sure I agree. Therefore I wrote of a laboratory video. The soil is encased in a box, therefore the water has no way to exit to the side accelerating the liquefaction. The missing foundation don't have any influence on the process.
RDG467Plus, the shaking force was parallel to the ground surface, not perpendicular, as would occur under the relatively low-frequency cyclical loading of a unit oil train. Which is mostly absorbed by the wooden ties and ballast anyhow.
The effect would have been the same with vertically oriented vibrations. Horizontal vibrations are only easier to generate in laboratory.
Here is a homemade video showing the liquefaction caused by vertical shocks: https://www.youtube.com/watch?v=b_aIm5oi5eAAnd here is another video that had already been linked showing how easy liquefaction is caused under special circumstances: https://www.youtube.com/watch?v=Rd6W2aP2dkA
The last time I stood beside the track on Tehachapi the earth shook and the vibrations showed in the video. The camera stood on a tripod about 15 ft off the track.
Again, there are many possible causes for the derailment and I don't rule out Liquefaction.Regards, Volker
One only needs to stand near the UP Geneva Sub tracks (generally very well maintained) as a train with some wheels with flat spots (usually covered hoppers or box cars, not auto transporters, tank cars or IM flats) goes by to feel the strong vertical shocks.
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