bearing capacity on a larger area
bearing capacity on a larger area
(OP)
I recently ran into problems about calculating the bearing capacity in large areas like a landfill. The Terzaghi theory and all the others are based on footings on a small area (strip, square, etc). What is the appropriate way to calc the bearing capacity for a large area as a whole?
Also, there are only equations calculating the stress distribution in the ground under a load/stress that applies in a small area. How to find the stress distribution under a stress/load that (say evenly) applies to a very large area (like in a landfill)?
Also, there are only equations calculating the stress distribution in the ground under a load/stress that applies in a small area. How to find the stress distribution under a stress/load that (say evenly) applies to a very large area (like in a landfill)?





RE: bearing capacity on a larger area
Just my opinion.
f-d
¡papá gordo ain’t no madre flaca!
RE: bearing capacity on a larger area
As to landfill, I am wondering the Settlement calc. If a height of waste (surcharge) is applied, should I assume this load will induce the same stress (unit weight x waste height)in the sugrade (no matter how deep it is)? Because Bousenesq's theory again applies to footings only. That stress may be used for consolidation calc. But How to get immediate settlement in landfill case?
These questions are all about applying load in a very large area, and the current theory seems to be all about footings.
RE: bearing capacity on a larger area
Why don't you google for articles on settlements of and in landfills? There are a number of papers I have seen that address this issue.
Now with landfills, you will also have to deal with long term (secondary) consolidations and also of settlements due to decay.
RE: bearing capacity on a larger area
To make my questions clear, I made a simple problem: Say, an area of 3000ftx3000ft site with orinal soil of clay, (or silt, or sand), now apply a stress (say 10,000 psf)over the site (equal to placing fill on top), what will be way to find out the settlement and bearing capacity? Embankment looks different from this. And why can we ignore bearing capacity like Fattdad said? I think there should be theory to address them. But So far I have no luck to it..
RE: bearing capacity on a larger area
RE: bearing capacity on a larger area
RE: bearing capacity on a larger area
As the fill is applied, there is a change in the stresses in the clay. With this change in stress there is an increase in the undrained shear strength. When looking at large areal fills, the tendency is to do a "gravity turnon" type analysis, which won't work. You really need to look at the incremental addition of load.
Regarding the settlement, you can use Bousinesq to determine the increase of vertical stress with depth. However, as you will quickly realize it takes a great depth to show any real attenuation (i.e., the seat of settlement will go down several thousand feet). Because of this problem, you have to look at the soil modulus as a function of confining stress. The best way to do this is via the hyperbolic model. I would expect several feet of settlement will be realized by the liner system. Now you just have to consider the angular distortion and whether it exceeds the capacity of the liner.
Forget bearing capacity. Now that I said this, I also realize that the regulations are short sighted and written to require that you make some statement on the "bearing capacity". The "best" way to handle that is via slope stability, which is how the fundemental bearing capacity was determined in the first place (in my opinion).
This is truly a settlement/slope stability problem - now you just have to figure out how to repackage it to the regulators as a "bearing capacity" response.
f-d
¡papá gordo ain’t no madre flaca!
RE: bearing capacity on a larger area