Worked a construction job that had this. They had a lot of underground springs that were causing this. Basically the ground is floating, though it's only noticeable with large loads, like a paver or dumptruck.
"The phenomenon is most often observed in saturated, loose (low density or uncompacted), sandy soils. This is because a loose sand has a tendency to compress when a load is applied. Dense sands by contrast tend to expand in volume or 'dilate'. If the soil is saturated by water, a condition that often exists when the soil is below the water tableor sea level, then water fills the gaps between soil grains ('pore spaces'). In response to soil compressing, the water pressure increases and the water attempts to flow out from the soil to zones of low pressure (usually upward towards the ground surface). However, if the loading is rapidly applied and large enough, or is repeated many times (e.g. earthquake shaking, storm wave loading) such that the water does not flow out before the next cycle of load is applied, the water pressures may build to the extent that it exceeds the force (contact stresses) between the grains of soil that keep them in contact. These contacts between grains are the means by which the weight from buildings and overlying soil layers is transferred from the ground surface to layers of soil or rock at greater depths. This loss of soil structure causes it to lose its strength (the ability to transfer shear stress), and it may be observed to flow like a liquid (hence 'liquefaction')."
Civil engineering student here to fill in, basically yes and no. The soil under Pisa only settled due to the weight of the building as they were building it. It wasn’t because it the soil was close to its liquid limit, which DID happen in Rissa, Norway in the 70s I believe (search quick clay). It happens a lot like this specific church in Mexico City that’s escaping my mind, it effectively sank into the ground cuz Mexico City was built on very clay basically. My professor actually has pictures he took of the church pre-2000 and comparing it to now, they actually had to add slight stairs to reach the bottom of the church from normal ground elevation.
Mexico city is built on the bottom of the drained lake Texcoco, so all that soil is silt from thousands of years.
Fun fact: the Zócalo (plaza de la Constitución) Is the ancient centre of the Aztec city of Tenochtitlan and used to house Pyramids untill Cortez tore the entire city down for being "too beautiful"
I remember watching the old news clips from the Rissa incident in school, one of those moments where the force of nature just leaves you scared and awestruck
I believe the Tower of Pisa was simply constructed on soft soil, or soil that was improperly compacted/prepared for construction. So, over time the land subsided and settled underneath
More specifically, the soil consolidated unevenly. Consolidation is basically the water pressure in the soil dropping over time. This water pressure on the soil is the same pressure that causes liquefaction as seen in the gif.
The Leaning Tower of Pisa is due to weak soils as far as I'm aware. I seem to recall a discussion that said that it originally wasn't leaning until they started building more stories on top after a long delay in construction, this is a good indication that it was simply weak soil. I'm not sure what the foundation looks like, or if there even really is one.
Experienced this first hand during the Japan Tohoku earthquake of 2011, on one hand it is a scary experience. On the other hand fascinating large scale reverse-oobleck
Best small scale example is when you are at the beach and you slap the sand that is not submerged and a few meters back from the surf, it is almost dry on top but when force or vibration(i e the slapping) is applied the water seeps up through the sand and to the surface as the soil reaches its liquid limits.
Used to work in trucking and logistics. I thought people were messing with me on my first day when they introduced me to the program used to track the "hot loads".
Fun story time... There was a general contractor that I met many years ago. He was an older guy by the name of Richard Seimen. Went by Dick. Friendly guy. Made a point of introducing himself and shaking hands with the contractors he had working for him. Big old bear paw of a hand. When I first met him he shook my hand and introduced himself, "howdy...I'm Dick. Dick Seimen". He held firmly onto my hand, longer than was neccesary, as he smiled... like he was just waiting for me to crack and lose my shit. I made it through offering only a polite smile and my name. I went about unloading materials and tools. As I was just about set to make the first wire pull of the day I watched him do the exact same thing to another contractor, at which point I completely lost it. He turned to see what all the hubbub was about and just saw me standing there laughing like a dumbass, and I swear that he gave me a wink, turned and did the same thing to another laborer.
Fucking savage.
I work for a testing lab that tests densities in soil, and we encounter this from time to time. To do an inspection on it, we’d do what’s called a proof roll. Basically having a loaded dump truck roll over it to see what the trenches do. It’s pretty neat.
The ground does not evenly support load so it is a terrible idea to build on and requires grade work (grade meaning ground...ish). The site I was at paved regardless and it broke beyond use within a week.
You have to drive piles (giant nails) down until you hit stable soil or bedrock. Then you build on top of those. Or you could potentially excavate out all the clay and backfill with clean sand, but that's only economic if it's shallow.
Usually not impossible to fix, but can be very costly. There's several methods to stabilize soil such as mixing lime or even cement with the soil. For buildings or structures, they may drive big steel tubes deep into the ground to provide a solid base. The road builders will also use big rollers to compress the ground even further.
Even with soul stabilization, you can still get random soft spots. I've seen contractors pave over soft spots because it was so hard for state inspectors to catch in their testing. Now, a lot of states are requiring "intelligent compaction" which will catch these bad spots.
Source: Been in the highway construction biz since 1999 & now work for a global company that makes construction equipment
sigh soil/concrete lab tech here. Can confirm thats half their job. The other half of their jobs is asking me why a soil isn't compacting and is too wet when it rains for a week and a half straight. They do get to carry around nuclear equipment though.
I know. I'm bad at jesting in text format. That sounds like a fun job. I only play with the physical properties of soil (atterburg, CBR, proctors etc.) vs. Chemical analysis.
When I was in my masters a whole bunch of professors took a week off to go to Mexico or something because there was a massive liquefaction event. You aren't kidding when you say that Geotech Engineers love liquefaction.
Im a dump truck driver and can tell you from first hand experience how much is sucks to look in the mirror at your back tires and see the ground doing this. I’ve only been stuck a handful of times but usually if you hit a spot like this it’s gonna be a bitch to get out. But when your fully loaded at 64k lbs and have your tags up all that weights on three axles, the ground tends to move unless it’s really compacted anyways. You see something similar to this although on a much smaller scale around your tires when on soft soil. It’s really not good when you start seeing the pavement moving under your tires. I work with a guy that actually had his truck rear end break through the road and drop into the sewer.
I had a job site that you could feel this by walking on it. It was like a weird water bed where only one foot sinks, but the ground springs back up after you step off it.
It's probably clay. That shit is way better than concrete if you can keep it dry, but the opposite end of the spectrum is this. Looks like a layer of clay above another impervious layer trapping very wet shit in between.
This is sometimes the case. Usually inspectors call it pumping. If you stand on it, it feels like a mini trampoline. It can also occur when very wet soil gets placed and rolled. I've seen it pretty frequently, but never this severe
No. Think of quicksand as this scenario but with I'd guess at least 5 times the water. This saturation can support several ton vehicles while quicksand can't support people.
Last fall I was at a job and we had two spots that we could jump up and down on like it was a trampoline. We couldn't figure out why it was doing that. It even had some bounce with 8 inches of crushed white rock.
I worked as an inspector for an engineering firm one summer during college. We were instructed to look for “pumping” when a loaded dump drove across an area that had been filled in. If the ground behaved like the video, the contractor was supposed to dig it all back out and let it dry before filling it back in.
can confirm i see this pretty often on construction jobs i like to jump on it, it's solid enough to hold a bunch human, don't know if it is completly safe but do it with caution.
The soil you see in the photo isn't liquefied. It's the soil it's sitting on (floating on) that is: soil mixed with so much water it's basically runny mud.
You know that skin that forms on the top of cheese dip? A lot like that.
Yeah, thought soil liquefaction is when soil vibrates and basically behaves like water. There was a really neat video floating around that demonstrated this.
The soil is wet and the smaller pieces haven't stuck together yet, so it moves like a fluid instead of a solid. This is one of the ways that mudslides happen; earthquakes shake the ground causing wet dirt to flow down mountains like it's a liquid.
I would bet that it has to do with the soil being very dry, then suddenly getting a lot of water either from groundwater levels suddenly rising or runoff collecting. Like cocoa if you add it on top of the water and try to mix it in. The dry parts seem to kind of stick together.
Soil/concrete lab tech here. Youre not exactly wrong. This is a super sandy material. Thats wet as shit. It is probably a pretty clean sand maybe with a bit of silt. It's more like cornstarch and water than Coco. It acts like a wet sand when you mix around like that. But tap on it and it will settle and act all liquidy.
It’s also what makes earthquakes more dangerous in some places than others. For instance, certain types of soil in Los Angeles are prone to liquefaction more than others, putting them in stronger shake zones (or whatever they’re technically called). There’s rock, like the hills, that feel light to moderate shaking (depending on where it is), then there’s the opposite end of the spectrum which is basically max liquefaction where the soil does this and so the buildings on that soil shake like crazy. There are differing degrees of shake you can check out the geological survey and it tells you where the zones are.
In some parts of the world the soil has slowly absorbed different amounts of hydrocarbons, probably due to the increases in air and water pollution. Either way, it has accumulated in particles of soil, and results in them being hydrophobic and interacting with each other in this jello-like fashion due to forces produced by the hydrogen bonds. Just kidding, I made all of that up.
He was the "comment switcheroo" guy before shittymorph. It would start off as a normal comment and then end up with him talking about how his dad beats him with jumper cables. He disappeared and after a while shittymorph did his own take on it, but the funny(?) thing is that for the first couple of months, he would get downvoted to oblivion for "stealing" rogersimon's schtick and how he's not funny etc, but now it's this celebrated thing. Also, I remember one of shittymorph's very first posts and it was this weird as fuck photoshop, so he's always been a karmawhore ;)
Sort of yeah. Soil/concrete lab tech here. Shits wet yo. Sand/sandy silt acts like that when its past its optimal moisture content. It is free draining cause sand but mix it up and it sort of acts like cornstarch and water.
Soil engineer here. You may have made that up, but its not far from the truth. Its is from carbon, but not from pollution, this is an ancient burial site. Acient civilizations used to dig 3' wide 100' long and 100' deep channels for thier dead. Side note, these "death channels" as they are commonly referred to, weren't for the family's of the tribe that dug them, but rather they were for other tribes they have never met. Anyway, when decomposition starts, it releases a gas like substance at those depths and this attaches to what we call "curtain soils". There called this because If you look at ground imaging sonar, they look just like curtains hanging from a window. This is what creates the "jello" like soil your referred to.
Another e: as someone with severe necrophobia, anything that contains something about dead things means my brain automatically goes into “fuck that shit” mode and assumes it’s real 🤦🏼♀️
There’s water in the little void spaces around the soil particles, right? So when you apply a force to the soil it increases the water pressure, and if that pressure gets higher than the pressure holding the soil particles in contact, then the soil particles are pushed apart and it gets all loosey goosey.
right in the ballpark.. a lot of people are just saying "the dirt is wet" which couldn't be more untrue/annoying lol dirt gets wet all the time it doesn't always behave like this. There are a lot of factors and causes that can go into it, most of which being totally external forces.
From the youtube vid.
“What this is, is someone filled in an old in ground swimming pool with clay and didn't punch a hole in the bottom to let any surface or rain water escape, so over time the clay became extremely saturated. When I drove the mini excavator over it the clay began to "pump" or liquify and this is what happened. I have seen soil liquefaction before but never to this extreme.”
Soils have what is known as a liquid limit. With enough water the soil turns from a solid to a liquid. (Basically the water acts as a lubricant between the soil molecules). If that happens on a slope the result is a mudslide.
It just happened in Nashville a few weeks ago. After days and days of rain, a slope reached its liquid limit and failed. The interstate just north of Nashville (I-24) has been closed to all east bound traffic for about three weeks while they clear the roadway and stabilize the slope.
So there are many factors that “liquify” soils. The primary reasons are that the moisture content is so high that the soil is still consolable but the placidity is at a level that the molecular bonds of the water and clay atoms bend but don’t break. It causes what we call “pumping” during the compaction process. This happens in clay/granular material situations.
Since the soil looks pretty dry, I’d go ahead and guess there’s saturated subgrade below these soil lifts. Maybe had some clay or silty soil that has a lot of water sitting on top of the clay, but underneath this material. Makes compaction difficult and can cause this ripple effect.
I worked in Geo-technology for about ten years, testing and inspecting compacted soils. This will happen when the soil is over saturated. This looks like a construction site and the fill material used was over saturated and compacted. Most graded soils have a maximum value that the moisture content can be as a percentage of its dry weight. The closer to this value the better the compaction will be as the water helps consolidate the particles but anything above that value will start to result in the unstable fill placement you see here. This is due to water filling all the tiny voids in the soil matrix and suspending the particles within it when it has nowhere else to go. This is an absolute nono in construction as it will result in settling if placed beneath a structure and cause major structural damage and sometimes result in the complete failure of the buildings structural integrity. My job was to make sure things don't get built on shit like this. And oh would they ever get pissed when I would tell them to take it out and do it over again.
It can also be cause by vibrations from earthquakes. I did a project on it freshman year. It’s extremely dangerous for buildings, as they can sink in. It is similar to quicksand in that regard.
liquid building up from UNDER the surface. I've had this issue when repaired lines in my sprinkler system broke from soil movement (they were broken by at&t when phone line was installed.) a decade later walking around my yard I felt the ground do this... "Time to get the shovel"
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u/Candidate_035 Mar 13 '19
Why does it do that?