Geotechnical Analysis of Foundations
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- Опубликовано: 16 май 2024
- Our understanding of soil mechanics has drastically improved over the last 100 years. This video investigates a geotechnical foundation failure that happened as a result of lack of knowledge and poor site investigation. With our understanding of soil mechanics today we completely explain what went wrong. The failure in question is the Transcona Grain Elevator in Winnipeg, Canada that failed during its first filling in 1913. The explanation lies in understanding foundation design principles and bearing capacity which is what the video is mostly revolving around. The video attempts to explain these concepts in an intuitive and easily understandable way.
Geotechnical Series Videos:
1. Understanding why soils fail ( • Understanding why soil... )
2. Understanding the Soil Mechanics of Retaining Walls ( • Understanding the soil... )
3. Geotechnical Analysis of Foundations ( • Geotechnical Analysis ... )
4. The Leading Cause of Foundation Failures ( • Residential Foundation... )
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References:
[1] A. M. Puzrin, E. E. Alonso and N. M. Pinyol, Geomechanics of Failure, New York: Springer, 2010.
[2] A. Allaire, "The Failure and Righting of a Million-Bushel Grain Elevator," American Society of Civil Engineers, 1916.
[3] J. Blatz and K. Skaftfeld, "The Transcona Grain Elevator Failure: A Modern Perspective 90 Years Later," in Canadian Geotechnical Conference, Winnipeg, 2003.
[4] D. P. Coduto, M.-c. R. Yeung and W. A. Kitch, Geotechnical Engineering Principles and Practices, Pearson, 2011.
[5] G. Wichers, "Manitoba Co-operator," 26 November 2021. [Online]. Available: www.manitobacooperator.ca/far.... [Accessed 20 December 2022]. 
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I think we all would be totally interested to see the engineering of righting the grain bins. This video was very educational, because I was not aware of how the shear plane forms.
what happen Putin happened there🤣
There is several videos. 1 has actual photos from the righting of the silos
I second this please
I think it is ridicolous dont understand this in 40 seconds...
It is amazing that they salvaged the silos, especially for that time period.
I imagine it was somewhat similar to the lifting of buildings in Sacramento CA above the flood plain.
That was done very carefully with lots of jacks and even while the businesses remained open.
I'd say they would of had a better chance back then as the structure would of been built alot stronger and _overengineered_ compared to today's leaner cost cutting engineering.
Think about what Galveston Texas did after the 1900 hurricane: they raised over 500 city blocks worth of buildings anywhere from 8 to 17 ft above existing grade as daily life went on around them.
@@stevebengel1346 IIRC Seattle also did something similar. It seems like this was super common.
I was thinking of the same thing.
This is somewhat similar to what could have happened at my old University. They were planning a big, major campus upgrade. The old veteran geologist professor warned the construction survey team of the ground condition at the planned site and that their proposed foundation would not hold and that they would need to dig deeper for the concrete rebar piles and further down for the foundation. They brushed him off and began laying the piles and foundation, only for the ground to give in in some places as they were drilling the holes for the piles and de-level the early parts of the foundation being set (that layer of dirt and rock meant to be flattened and built on top of). They were forced to correct their mistakes at their expense, which delayed the grand opening of the new science hall by a year as a more comprehensive survey was done, which ended up matching the old geologist professor's claims.
Indeed! My Alma Mater University of Louisville has a Physics building with many structural support columns in the basement because of the sediments underneath; without them, the building wouldn't stand but buckle and slide or worse.
I don't know much about this, but here are my thoughts.
The building has its wide face facing the street while it's narrow sides face perpendicular to the street. It sits on a hill that descends toward the street. It might be that the building is held up by the street itself: that the street and its heavy traffic provide pressure on that place that might otherwise buckle upward as the building pushes down.
Imagine being dumb enough to think "Yeah, I did a 6 week course on this, what could the professor who taught the guy who taught me possibly know about his own back yard?"
The university I graduated from was hitby a major earthquake. Many of the buildings were condemned but the civil engineering department was fine. That was reassuring.
Ignore the advice of old men at your peril.
@Nigel Tolley many acidemics have no real world experience and are only able to recite a textbook.
I grew up in South Transcona on the wrong side of the tracks ( or wrong side of the CN shops). I can concur that this is a very wet location. Every spring the floods would fill up the streets around my house. I have fond memories of floating around on rafts made from scrap wood or the occasional wooden bridge that floated away from someone's front sidewalk ( we had ditches on both sides of the road. Fun for the kids, but the parents were less impressed. If the city didn't get sand bags covering the manholes for the sewers in time we were treated to sewer backups in our basements. The city finally built a storage pond big enough to capture all the spring runoff which cured that problem.
My parents bought a house here in the first phase of what was to be a subdivision of roughly 4500 houses. The tar roads and ditches were just temporary until the rest of the development was to be built with storm sewers and paved roads. That didn't happen and the original hundred or so home owners were screwed. No schools or shops or any amenities. They stopped when the developers found out how water logged and unsuitable this place was.
The soil here is top soil on heavy clay with a gravely wet mix blow that. My father was digging out a hole (sink hole really ) in our front yard by the ditch. The shovel got stuck down in the hole and just got sucked in never to be seen again. Still there somewhere down below. I can see how a ,ess than perfect foundation would end in disaster here.
Sorry for the long post but it isn't everyday a story that is literally in my childhood backyard comes up in my feed. Thanks for the video.
Thank you for sharing numb, we appreciate stories from the locals. I am from a different part of Canada so never had the chance to visit Winnipeg but your description paints a very clear picture of what the geology/hydrology of the area is. Thank you, cheers!
@@TheEngineeringHub This was a case study that I got to hear and read about in our Geotechnical engineering textbook at the U of M. I always enjoy seeing something local like this unexpectedly.
I love the format of these videos. As a visual learner, the graphics and demonstrations, like with the straws, helps me a lot to understand. Thankyou!
Glad you like them! More to come!
@@TheEngineeringHub Can you do about engineering of foundations underground mining? We need to know the evolution of their structural shapes. I'm still confused with people using woods to support their tunnels, and I don't know their limits. Steels are expensive.
@@davidarvingumazon5024 Wood is cheap and easily available in most distant mining locations, easily cut to length, and has great holding capacity. Using steel, you would still need something rigid to spread the load, else the steel would be driven like a nail into the earth. Very much like foundations!
Geotechnical, I grew up in East End of Transcona, and had NO IDEA what this vid was about. I just saw a cool tilted structure! Something interesting for you maybe? Transcona was built on a dried out (for the most part) swamp. The entire suburb was once owned by a few farming families. There is a section about a mile and a half away that was a swamp when I was a kid. Freshwater springs brought water up to surface. In 60s, occasionally, the stupider kids (me?) would swim in there. When land prices increased. developers bought and drained the land, and rerouted the spring. Fast forward 20 years, and foundations were breaking on all the streets located above where the spring was. If I remember there were well over 100 houses involved. Imagine coming home after work, and you can't open your front door, as the door is jammed in the frame. This exact scenario played out over and over and over again. Developers denied all responsibility.
KK: Of course they do, with some justification.
The city (or county) building department reserves the legal right to review, AND APPROVE, all construction plans and drawings. Except for a garden shed below a certain size:-))
Legally that means that some responsibility is shared with that approving department of the government.
Although I am not a lawyer, a law suit by my employer proved that such "approval" by a government body does entail acceptance of such responsibility. My employer won that law suit.
Lol. The old horse pond & the cordite ditch
I remember alot of that. Lol. Remember when Wayoata street was the end of the eastside & kildare to the north. When they built Murdoch McKay just inside of Duffys ditch. That used to be Clays farm. I hated that mile walk across the open field.
I used to play in that old elevator. Its accessed off Springfield road. Parish & Heinbecker bought it years ago & put it to work. Was still in use the last time I was back 4 years ago.
I transferred out in 75. Lived in Transcona for almost 20 years. 500 block of Victoria east
When I heard Transcona in the video when I watched it on Sunday I assumed it was some other Transcona. Then he mentioned winnipeg at the end and I got curious where the building was.
Today I was out for a xc ski at harbourview golf course, and bam, there it was.
It would be interesting to hear what you have to say about the Milenium Tower in San Francisco and the efforts to stabilise /save it.
That's an excellent example! It could end up being a nice video 🤔
Pisan envy.
As a pile driver, I would also like to hear your thoughts on cast in place pilings in the San Francisco "bay mud". After seeing the way they were drilled, filled with concrete or grout, and how the rebar cages are literally shoved into collapsed holes and called good... Well, it has always baffled me. I have 3 years of experience in dcip and it was some of the most horrendous pile installation I've ever seen and took part in... and I took no pride in it.
One day I'm going to hear about one of those projects on the news, just like the millennium tower.
@@TheEngineeringHub So get busy before it falls over.
I'm reminded of two similar failures relatively nearby, in the Fargo area, also on the Glacial Lake Agassiz lakebed - the Stockwood Fill east of Glyndon MN in the same timeframe as the Transcona failure, and a Fargo grain elevator built in the 1950's that failed similarly to Transcona but was unsalvageable.
Thanks for the video. I have a failed home foundation on the north slope of Astoria, Oregon. I am continuing to study our options...we are at the top of one of 75 active landslides in Astoria.
I read in (I think in: Brown's Foundation Engineering Handbook) about a rather famous settlement of a public building in Mexico. The building settled evenly making the second floor the first floor! And, I believe it is still in use today. PS: our geologist tells us that our fabulous view of the Columbia River, gets better every day.
Interesting video. Kind of nostalgic for me. This was pretty much "right in my backyard'. I grew up just north of Transcona and took my civil engineering degree from the University of Manitoba (way back). We studied this failure as part of the geotechnical curriculum. Thanks for posting. I also have that exact steel design and wood design manual in my 'library'. Although I don't practice engineering any longer, they are still great reference manuals.
I took mechanical engineering at the U of M and remember the large black and white picture of this in one of the hallways. My older brother took civil there and they covered this failure as well.
I actually used to work in this grain elevator, as a subcontracted electrician for maintenance.
Have lots of photos on my phone of all the old pulleys and DC motors.
As far as I know, this elevator is now vacant as of 2021 or so, serious foundation issues I heard, and the owners have moved to a brand new elevator out East of Winnipeg, past the town of Dugald.
IF they had foundation issues to begin with, I can't imagine how bad they are now. I think the elevator should be preserved though.
What a great video! I learned more through it than in the lectures I received in my geotechnical engineering classes 25 years ago.
Thank you so much ezegroup! We are very glad you found the video informative, check out some of our previous videos on geotechnical topics you may enjoy those as well. Cheers!
@@TheEngineeringHub oh, yes. I’ve got quite a few that I need to watch!
@ezegroup22 Great! Let us know how we did! Positive or negative, any feedback is appreciated 🙏
If you enjoyed this video, you may also enjoy the next video in this series on:
The Leading Cause of Foundation Failures
( ruclips.net/video/qR5PrbDBCLw/видео.html )
Fascinating! This video explains why the plates and blocks I used to lift up a combine harvester in a field not just settled, but tilted as I operated the jacks. A much larger plate would have helped to increase the stability, and thus the safety.
But a larger plate would destroy more unharvested crops . For temporarily lifting a combine harvester, pushing around the soil at each location is acceptable and easily undone by plowing the field before sowing the next crop, as is tradition anyway.
@@johndododoe1411 not the OP but having a few more square meters of crop disturbed is a lot less expensive than the ground shifting and dropping the combine in an awkward position that damages it. In addition, the odds are that the ground you are setting the plates and blocks on has already had the combine remove the crop being harvested anyways. Finally, most farmers engage in zero-till seeding now where they plant directing into the stubble of the previous year's crop as this reduces soil erosion during spring runoff or heavy rains as well as reducing moisture loss that occurs when the ground is cultivated.
@@ylevre3285 I thought lifting the combine would be after a breakdown with unharvested crops on 2 of 4 sides .
@@johndododoe1411 I'd say that is generally correct, but because the combine header (intake) is at the very front of the machine that means that all the lift points underneath are going to have been cleared already. Any damage you need to do on the crop sides from there on will likely need to be done no matter if your final plates are 50cm per side or 150 cm per side
Oh I would happily watch a video on the righting of the silos! :)
Clear explanation, good graphics... a pleasure to watch. Thank you.
Thanks, a whole new field of engineering for me - it's astonishing that they were able to fix and re-right the silos after that failure - good old fashioned engineering, rather than the demolish and start again approach these days!
the entire thing was structural metal, so not really fair to compare that to the failiure of most buildings
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Not bad! The experiment with the bottle, however, is somewhat misleading as it does not include a foundation between the bottle and the straws.
I am not familiar with how grain silos are loaded, is one silo loaded to capacity then the next? Or are they loaded simultaneously? I see a distribution arrangement on top, but I assume there would be gates to regulate flow into different silos. I wonder what role if any of uneven distribution of weight may have played, say if the bins were started to fill from front to back, or one side to the other.
@@brennans1563 Yes and the rounded edge on the bottle would serve as a additional source of slippage, given the "grain" size of the straws, but I think overall it does a good job of providing a visualization of the "underlying" principles...
Your straw model is wonderful. Please extend it and do ananalysis video using straws of different diameters, mixed, or in planes, or in patches.
The underpinning thought is a realisation of mine of looking at solid, liquid and gaseous not as aggregate states, but rather as behaviour. This behaviour is determined in the most simple case by the mixing ratio of two homogenous particulate grain sizes. Exemplified by ground coffee (KG1) in its vacuum package (KG1=100%) behaving solid until a hole is punched and upon air (KG2, where KG2 KG1:KG2 = 90/10 -> 80/20 -> 70/30 etc. over time) - you can now "pour" it out.
I have passed near this structure many times. I've never heard of this failure before
Excellent video !!
It appears that the Tower of Pisa could have failed due to the same failure described in your video👍
They also could have prevented this collapse the same way as Pisa did.. but that depends on how fast the collapse happened. If it was noticible, they could have left one side empty, which would counteract the tilt.. but with that weak clay layer, it could easily have gone the other way then.
Kudos to whoever build them though.. those silos survived a collapse!
What amused me about Pisa was that it began to tilt during construction and the builders tried to compensate for the lean by making the building curved. The tower has a slight curve.
@@darylcheshire1618 😳😳😳 "curved" wow, I never heard that story😳
As always a great video. It would be nice if we can have a separate video on Terzaghi's Failure Model and the Bearing Capacity Equations.
Great suggestion!
Really awesome video! Well explained. Look forward to more videos soon.
Best part of the video is using O86 and S16 as the end stops for the experiment. We'll done mate.
Great demo and explanation of shear failure. Learned some history on it from the vid.
Wow this series on Geotechnical topics is really awesome!
Can you please do the next part on piles / deep foundations?
Cheers!
Second that on piles/deep foundations, especially under-sea (like SF Bay Bridge).
7:27 Much of the parts of New Orleans and it's suburbs that were built up after 1950 suffer serious subsidence problems, since new land was created by filling in marsh and reclaiming the edge of the nearby lake. I remember driving down cracked and undulating streets, while seeing two foot gaps under house slabs.
Everything East of Michigan Ave is debris from the Great Chicago Fire that was pushed out into Lake Michigan after the fire so all buildings built there have to have pilings that extend down to solid ground.
That building is about 5 kilometers from our house , here in Winnipeg . I'm still amazed that they got a handle on this mess in 1913 .
Excellent presentation. I'm not an engineer, but I'm always interested in how and why things happen from a scientific perspective. This really helped me to understand how, what seemed like a well-tested design, failed for reasons that are now much better understood.
Knowing how they brought it back up would be very interesting
The leaning tower of Pisa foundations would be an interesting topic.
And a potential example for ground settling slowly under a foundation, he asked for examples of that to use in a future video.
Factor of safety is important here, which is the ratio of ultimate failure load to design (actual load). In every civil mechanical structure the factor of safety is used, if variable are unmeasurable or not measured it is increased. It could be high as 8 for tractors or 1.2 for rockets. In general engineering structures it is 3 to 4.
A low safety factor for rockets makes sense. These things are so precisely engineered with extremely high quality control for the materials so that the possible loads are highly predictable.
And they also need to minimize total weight as much as possible.
The factor of safety is usually taken against the computed "ultimate" strength (resistance) of the soil. Note, however, that this is the strength limit state and it may require that the soils move (settle) a great deal to fully mobilize the available resistance. In many cases, the usable strength is dictated by the settlement tolerance of the structure being supported - known as the serviceability limit state.
That was really interesting! It explains something that I've often wondered about concerning foundations.
Subscribed
@7:05 The author asserts that the main reason that foundations are dug into the soil is to extend the slip plane. That may be true in climates without winter, but I assert that in climates with winter, digging in to get under the frost line - the depth to which the soil freezes in winter - is a much more pressing reason to dig a foundation deep into the soil. If water gets under the foundation during warmer temperatures, then freezes in the winter, it can cause heaving, cracking, even collapse of the foundation, especially over years of freezing and thawing.
Otherwise, good video, and thank you!
Absolutely! There are many reasons why burying a foundation is a good idea. The extension of the slip plane and soil confinment are just two of many reasons. Frost is another excellent example, thanks!
Thank you for your acknowledgements and feedback.
One came to my mind: St Mark basilica in Venice. I visited the basilica in 1989 and was surprised at how crooky and lumpy the flooring was. I could see from a certain distance that the basilica wasn't level. Pisa tower is famous and most visible example of foundation failure. Another is the Millennium Tower in San Francisco that is leaning 28 inches at the top, leading to the enormous engineering challenges of finding the optimal solution for stabilising the skyscraper (hopefully before the next Big One hits).
And to think I used to play there when I was a kid.
I think it was in the late 70s when these elevators were finally put to intended use.
The long sides face north & south. The west side of the silos have settled & remain that way still today
Very nice, concise and informative video. Thanks for sharing.
I am not a soil engineer....................... but this video and failure explanation is FASCINATING!!!!
This was great, especially the straw model. I'd love to have a similar analysis of the Millenium Tower in San Francisco.
Yes! I'm scared by the fact that could be an actual water well underneath that building. "The Leaning Tower of San Francisco."
Edit: Also, please do the liquifaction events during the 1906 Quake...like the Valencia Hotel. (Proof wooden buildings are not safer than brick if your foundation is built upon old wetlands or creeks.)
Thank you for this video...I love engineering marvels and solving and understanding engineering failed events and projects.
Well done! Thank you. Were thelevator cylinders filled equally? Or was there more weight on.e side than the other?
As time past I grabbed every chance to see a fallen crane or cracked building or over settled structure.
It made my engineering perspective more real.
Very nicely done video, more detail about the righting of the elevator would be nice to see. Charles
By me, due to a lot of the soils being wet sand and silt, many of the large buildings in the city are built on pilings, that go down to a bedrock layer some 30m/100ft down, so that the buildings do not settle into the ground. Even for buildings that are 3 floors many were built that way, simply because there were so many other buildings that settled down over time, despite having massive floating slab foundations. You have to come out of the city basin before you find simple non piled foundations, and even there many still use deep piling to get stable foundations that will not shift.
One large centre was rather infamous for having an expansion joint, that opened up big enough that you could put a ladder between the 2 floors, and climb between them. They fixed it by casting in a new section of slab to close it up again, after the motion had subsided, and putting in a massive effort involving digging out the fill (what caused the issue) and piling under the half to both expand the centre, and to provide a large area of foundation on existing soil as well.
university has the one building that has moved around 5m down the hillside it was built on, as a unit, due to them underestimating the piling requirement, but the concrete structure is strong enough to handle it. Ironically, it does contain parts of the civil engineering faculty, and the other side is known as the most accurately surveyed hill in the area, seeing as it get surveyed around 100 times a year in training students.
We've had subsiding problems here caused by big building projects which in turn caused a lowering of the water table, leading to many cracks in old buildings. At least around here, it was a huge thing.
Here = Münster (Westf.), Germany. (As in, peace of Westphalia.)
Great video! I have actually been wanting to build a model similar to what you have shown to help better explain this concept. Time to go buy some straws! Haha thanks!
Hi Park! Thanks for the comment, starws of varying diameters might be even better. That would represent the soil better since the particle size distribution in the soils could vary a lot.
No longer available in Europe. I hope you live somewhere else or cardboard straws have to be good enough.
I'm not an engineer or architect, but this was quite fascinating!
I'm glad you are getting some value out of your CISC design handbook finally. :P
Great concise video. Proves that assumptions can make or break a design. In this case a surface test did not reveal the weakness lurking below. I assume a valid test would have to be a drilled hole then inserting a pole to load test. And A driven pile would skew the bearing capacity because it compresses the soil beneath the pile.
And the soil beside the pile. It creates a load bearing column that is of significantly larger than the area of the pile. Of course, that depends on the shape of the pile.
What would be the best way to strengthen the foundations in this example?
Would piling the foundations, to effectively deepen the triangle wedge of earth under the them, provide more stability?
Would widening the foundations be better?
Would digging the foundations deeper be best option?
Or would any of those options be viable?
Great video and explanation. I'm subscribing!
San Marco in Venice did settle unevenly since its construction, managing to deform its own Tarrazzo floors in the outer areas but keeping its inner floors mostly flat.
Something similar was happening at the Anderson Plant (Conant Street) in Maumee, Ohio, although not as extreme. They still use the grain bins, but at only 50%.
We are building a ranch style bungalow and the builder has requested a soil test . Do you usually increase the footing size to be able to handle the load for the basement foundation?
Really cool video! I never understood this phenomenon before. I have a suggestion - if you use different colored straws for each layer, we could visualize it much better. See just how far soils from below, climb up to the top. (And how upper layers sink!) Thank you, eagerly awaiting more.
Great tip! Thank you, settlement coming up next! In meanwhile you can check out our latest video on the Comet - The Plane That Kept on Crashing! Cheers!
I had always thought that the depth of foundations (unless they are raft foundations) was determined by how far down it was necessary to go to get either to bedrock or to hard, compacted subsoil which would resist compression. I’d certainly have imagined this grain silo was built on piles, but it seems it was just a relatively shallow slab.
Brilliant presentation. Thanks.
Touché...but also, the soil type is important. As a Geologist, in my country we never use the 300mm plate, only 600m to 720mm plate. Also we use the DIP test and Troxler test. And if needed we complement with CPT and/or DPSH.
Is there anything to learn about the February 12, 2014 collapse of the Corvette Museum in Bowling Green Kentucky?
Yes, Kentucky has a lot of Karst topography and extensive Mammoth Cave Park (near Bowling Green), but what can they do to prevent another collapse like that?
Also, would LIGO help analyze soil? It has uncovered buried cities and underground structures.
Can loose soil be compressed and compacted before building on it?
Can a concave foundation solve that ?
I used to chuckle reading the geotechnical reports, talk about CYA language. That told me it was not an exact science. One situation that cropped up over and over was trench settlement. Contractors universally detested having to compact the trench spoils in lifts and if they were not watched they often would not do it.
A huge condominium tower had to be demolished on the Texas USA sandbar island of South Padre Island. This was quite recent, and it seems surprising that the engineers were once again incorrect in estimating the soil's capacity. It was an EPIC failure.
All the crazy corrections made to the Leaning Tower of Pisa, which began to lean DURING construction, so they built a curve into it!
... and the engineering afterwards was just as wacky, monster lead blocks, grout injections, hydraulic jacks and more! It's like a smorgasbord of engineering fixes over the centuries.
ALSO: Titanic, Hindenburg, Challenger, Columbia, Upper Big Branch Mine, Deep Water Horizon Oilwell, etc, in which accountants overruled engineers to cut costs, and wound up cutting throats.
Excellent explanation I guess this will also apply to buildings like those on Venice?
Great presentation
Never will I do any kind of work like this, just knowing what is below my feet and above my head is interesting. Every day structures, bridges, skyscrapers, highways ,this could be a long list of infrastructure designs that most of us don't put a second thought into but use every day are important, thanks for the knowledge.
Muy bien hecho el video y muy informativo su contenido.
Have you done a video about the failed foundation and the failed repair attempts on the Millennium tower in San Francisco?
Thank you very much, Im an armchair engineer and love to learn from videos like this.
Here's a question: Why do they pack sand and level it when building foundations? Is the compaction force applied to the soil and sand mixture important when building large buildings that are only 1 or 2 stories high?
Great video. I would like to see the cideo where they uprighted the structure. Can you post a link?
Hi Roger, that video is not produced yet. It was just a consideration for a future video to see if there is interest among the viewers.
@@TheEngineeringHub If you can find historical photos of the work and the correction, it would be fantastic!
reminds me of the coal stage at Ararat in 1970 it was a massive concrete structure. An attempt was made to demolish it and it leaned over at 45 degrees and stayed that way for a week. Later it was demolished,.
Absolutely fascinating
Wonder if the bins were filled in a certain order so as not to place a disproportionate amount of weight in any one area or would that not need to be factored in?
Excellent video from a layperson perspective.
One consideration that occurred to me was whether or not the silos were not filled and emptied in a way that kept the load balanced on the foundation. Much the same has how a bulk ore carrier needs to be filled or emptied.
that was an excellent presentation
Great video! I love structural analysis of failure. One observation, though.. another video on the reconstruction would be great, because while I now understand well what went wrong, I am extremely curious to know how this problem was solved-- I think its equally important to know how to work around such a slip fault, as it is to know it exists. SO did they just basically make the foundation bigger?
They basically excavated under the side that was up and let it sink down until it was level. Then, they reconstructed all the conveyors and elevators to work with this new elevation (simple explanation). Interestingly, this was all possible because the concrete structure i.e. the bins were (way) overdesigned, so the concrete only had minor cracking. If this failure occurred today, my guess would be that the bins would crumble under their own weight, as the structure leans to the side. In the tilted structure, those bin walls were undergoing heavy bending (something they were not designed for), and yet they had no problem doing this new task 😅.
@@TheEngineeringHub well this is good, but given that the soil composition was at fault to begin with, how was that part mitigated? can one imagine that after the soil had moved, it was then at its final rest state? fully compacted, so to speak? Using the straw model, they removed some straws from the uplifted side until the whole structure leaned level again, and figured that then essentially the soil underneath had moved all that it was going to? because by digging lower they were essentially going even further into the disconformity.
To be honest, the literature that I read never mentioned how they knew that the problem was mitigated. In fact, I think they didn't. It took many years to solve the mystery, so I think they just thought oh well the structure hasn't moved for a year, so it's probably in equilibrium. I think your explanation is probably close to the truth. Since the failure stopped at this point (this tilt angle), it probably meant that it encountered some kind of resistance or the soil got compacted and its strength increased. What is often the case with clays is that if they are loaded slowly over a longer period, they will get stronger as they get consolidated. The problem with the initial failure was that the bins were filled up so quick that the soil didn't have time to drain and compact so it failed. One of the references mentioned that if the bins were filled slowly over the period of one year the failure probably would have never happened. This is new knowledge that we understand now and often implemented on construction sites. Huge piles of dirt are placed where the building foundation would be and left there for a big part of the year so that the soil will be preloaded and drain.
Do piles around the edge of the foundation pin the triangle of soil below the foundation to the otherside of the slip plane increasing the force needed for it to slip?
yeah, but, unless it's already slipping, you have no idea where the slip plane is going to be :D The building could as easily have decided to turn the other direction...
Hmmm, I wonder if there is a record of the condition of fill of the various silos. If all the silos were empty, and loading began with an outer row of silos progressing towards the middle, an overturning moment would be introduced in the foundation slab. This could start the shear failure of the soil below the foundation.
I'm surprised that no test borings were conducted to investigate soil conditions for some distance below the footing, say at least to the lowest extend of the "sphere of influence" as shown on your animation diagram.
as the video says, they did do borings, but only **looked** at the bottom half. It looked the same as the top half so they didn't test it. They were wrong
Ah...My own backyard. This is the Red River Clay soil that we live in. Transcona today is dry only where massive drainage systems have been put in place.
Good video, the original design error was only a couple of %, assuming they'd allowed % 33 factor of safety. Which they clearly had. The fos I would argue was an error and should have been two to three times the characteristic load
In Winnipeg, in winter, frost frequently reaches 2 meters deep. I wonder if this may have contributed in any manner to the failure.
geopiers are becoming more and more in use, I would appreciate a shear plane experiment on this new adaptation, thank you.
Could uneven grain loads in the silos themselves have contributed to the failure as well?
Here in Finland there is a difference with winter conditions eg frost. But also changes in the groundwater level due to excess rains etc. can also contribute to catastrophies. Sadly the global climate has changed radically with torrential rains in usually dry areas.
EDITED for completion:
This is so far from my area of expertise that I cannot succinctly describe it. I am a brilliant speller, an excellent writer, and an aspiring novelist. Conversely, I am as far from being a maths whiz as humanly possible. Yet I still find this remarkably interesting; enough so that I watched till the end.
I have a gangly, long-legged, visibly asymmetrical physique, which has suffered numerous structural injuries; sprains and a broken right shoulder from different ways of falling. I also have the capacity to walk with astounding quickness! I explain things in general terms of mechanical engineering (I lack the training or expertise for any depth), which from others' responses registers to some extent.
Hi David, the fact that you could follow the video until the end is a good sign that you (even though far from your area of expertise) may have an engineering (factual) way of looking at things on top of the story-telling writing perspective which I am sure you also excell at. Thanks for coming here! Cheers!
@@TheEngineeringHub , well, how kind of you to say! I usually hear "NERD ALERT! NERD ALERT! NERD ALERT!"
or 😠 "Know-it-all!"
I endeavour for intellect and rationality in all things. When people scold me for being the Spelling Police (therein admitting to being the spelling criminal?), I ask them if they would tolerate such sloppiness and error in maths. Sullen silence! 😳 SMH
Touting your brilliance as a speller invites closer inspection of your use of "till". 🙂
@@Graham_Wideman as opposed to "until"? Or "'til"?
If it would satisfy your abacus-itch, I am poor at maths. I am gangly and misshapen. I am unable to work, essentially trapped in suffocating poverty. These are horrid circumstances not of my causation, and completely beyond my capacity to resolve.
I am an aspiring novelist. For the practical, I hope to earn a worthy income. I endeavour to excellence, though I still make typos.
I just wish that your perverse picayunity had merit. I truly do not feel well (I dozed off whilst texting this), and I could use your assistance to improve my life. Since you seem so eager to offer criticism, and I infer, help, could you email me a thick crust mushroom pizza, mild sauce, a two- litre of Orange Crush, an 8-piece cinnamon roll with white icing, a few large jars of Randall great northern beans, three premade cornbread, and a half gallon of 3% milk from Kroger's, please? I am too weary to cook. (I am not good at it, anyway.) Remember: email them! 🙂
Then, please help me to find a way to have my notebook recharge its battery, so that I can return to what work I can do? That would be such a big help!
If you could pop by, I have a huge, long list of my other faults for you. They in their enormous quantity are really heavy, though. I have lost count, though it has to be well into the millions! Terribly embarrassing!
Till then . . . .
@@DavidRLentz Exactly. Not that it matters much in the grand scheme!
The obvious one is soil liquefaction in the San Francisco 1906 earthquake. We now have the Millennium Tower in torsion, partially supported on bedrock, which suggests to me they've created a pivot point in this model. Sand bed ultrasonic studies suggest a thixotropic breakdown of clay colloids may be pertinent.
Great visuals!
Houses in Amsterdam are on pilings. Some started leaning because the pilings started rotting when the groundwater level dropped.
Tilburg NL. Construction of one big lock in Wilhelmina canal, replacing 2 smaller ones. It would have a height difference of 7 meters, but it would also mean that the suburb to the west of the canal (Reeshof) would start to become unstable due to lowering the groundwater table....
One engineer and one city councel man were able, in the nick of time, to prevent a catastrophe. But the lock was already built....
Immediate sub, great video.
Uneven loading and unloading have an effect?
My Civil Engineering lecturer warned me of the danger of & how to calculate the slip circle in 1967. Unfortunately, I witnessed live on television in 1997, 2 ski chalets' concrete slabs slip onto each other after constant rain, killing 18 skiers in their sleep !
Just going to guess at the beginning, is it displacement?
Was the building loaded unevenly or why did it tip to one side? I imagine it takes a lot of asymmetrical load for it to not just settle down, but top on its side. Who was blamed for the failure and if my theory is right, is asymmetric load normally taken into consideration in such constructions with substantial variation in loading?
The bins were loaded evenly to avoid asymmetric loads. In one of the more recent (late 20th century) reports that I read it said that the building might have tipped because there was a slightly more solid ground on one side or that there was a large rock that made it settle a bit slower on one side compared to the other. Once the uneven settlement started, P-delta effects (2nd order positive feedback) became more prominent and drove the asymmetry further. Just a theory, the exact reason may never be said for certain 🤷♂️
Soils are not engineered materials, so there is natural variation in the available resistance from location to location in the same layer in horizontal and vertical directions. Wherever the weakest soil was present would govern where the movement/failure starts.
it only needs to tip a little in one direction to become unbalanced, and once it's a little unbalanced, unstable soil lets it become a lot more unbalanced.
The Logan neighborhood of Philadelphia was dangerously sinking back in 1986. You can find old news articles easily with a search. Cinders and ash were used to fill a creek bed on which the homes were built.
Nice love these videos
Thanks Adam! 🙏🙏
6:20 Anyone know the name or location of the tipped apartment building?
Lotus Riverside Block 7 in Shanghai, China
Amazing thank you
In your example, it is "all dirt all the way down" How does Terzaghi's work deal with overburden over bedrock? Around here for most buildings you just scrape off a meter or less of overburden to hit the granite of the Canadian shield, put in some pins and start pouring concrete.
There are methods for addressing layered soils and estimating the bearing capacity of foundations on and in rock.
Like all materials, rock fails in shear as well, just normally at much higher values of stress than soils.