I teach a class in soil science, and one of the things I have some difficulty with is that some of the students want a more engineering perspective, whereas my personal training is more in the ecological perspective.
I was trying to come up with at least one example of soil as an engineering medium (and why it's important) for my introductory lecture, and I remembered something I sort of half-watched on the History Channel the other day: The Leaning Tower of Pisa! Ting!*
So I looked up a bit about it and found a bit of discussion from a soil engineer. Perfect. The tower was built, apparently, on an unstable silty alluvium from a former estuary area. They are trying to stabilize it now.
Incidentally, if any of you lovely people have examples of soil-in-engineering, especially as sort of a "quick guide for non-engineers" and you let me know, I'd be forever grateful. I wish I were boned up more on the engineering principles behind soils.
(Frankly, I wish I knew more about engineering, plain and simple. If I were going back and were magically 18 again and were thinking of doing something different with my life, I'd seriously consider materials engineering; what I've seen of it, it looks fascinating.)
(*I often think "ting!" when I think of something that I think is clever; years and years ago, as a child, I read a Rumer Godden story (one of her doll stories) where a little girl who had been made to think she was rather dull started thinking of clever things and hearing "ting!" shortly after the Christmas fairy doll was placed on the tree. She attributed her newfound cleverness to the fairy doll's presence, but it turned out to be a Dumbo's feather sort of situation).
4 comments:
There is a book called, Why Buildings Fall Down, by Matthys Levy and Mario Salvadori. They talk about structural reasons as well as "mother earth" ones; Including the Tower of Pisa,the Pantheon and Galloping Gertie***CV
Gosh, that sure sounds like something I *should* know about, but I have no clue, beyond "water is important". I'm particularly thinking of how sinkholes can show up when the water table goes down (big news near my in-laws in Buffalo)--people generally think about water as being something that would make things sink, but the hydrated soil structure is stable and takes up more space.
I know just enough to know that I may have just been telling you that 2+2=4. Mention it if you find a good title--maybe that could link what I understand to ecology, which *I* think is supercool and can just barely scratch the surface.
Welcome to the Club! I had the same problem when I was teaching Soil Science. The basic problem is that students today seem to think they know best and no one ever told them about the having and eating of cakes.
Soil can be either a growth medium or a structural medium, but I know of no situation where is is both. I think you need to be clear about which one you are teaching and - if the latter - find an engineer to take the class for you.
I don't mean to sound harsh, my background is ecology too and I see soil as a living system in which everything is interconnected. Students may prefer a simple straight forward, stepwise approach, but we both know that (as a growth medium) soil just does not work that way. So I cannot help with engineering info, but if you want anything about soil as a growth medium, try www.swep.com.au
This link on sand boils (due to piping) is particularly fascinating to me, even though I don't live below (flood) water level.
Sand boils are indicative of soil piping, a form of soil erosion that occurs below the soil surface. It is associated with levee and dam failure as well as sink hole formation. In an urban setting, subsoil erosion into stormwater lines can result in street and building collapse. Some of my early soil science (pedology, not engineering) consulting involved a client with damage from soil piping. They called me because the engineers in town were not aware of it.
Soil piping needs turbulent flow - laminar flow is not a problem. Turbulent flow has higher velocity (due to eddies)and removes soil. It starts from the mouth of the seep flow and from there subsoil erosion advances upgradient, creating the "pipe". When the mounth of the seep is under water it creates the classic sandboil behavior: silt flows away but sand remains suspended in the tubulent upflow. Not what you want to see at the foot of a levee or a dam!
Sandboils 101: Corps has experience dealing with common flood danger.
http://www.hq.usace.army.mil/
cepa/pubs/jun06/story8.htm
Phil
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