What's the other term for "cone of compression"?

[Marcel R. Cyr]

Hope this helps.

Static load dispersement and distribution
The triangle of static loading transfer



In addition to providing a level platform for forms or masonry, footings spread out the weight of the house so the soil can carry the load. The load spreads out within the footing itself at about a 45-degree angle, and then spreads out in the soil at a steeper angle, more like 60-degrees from the horizontal.


As the load under a footing spreads out, pressure on the soil diminishes. Soil directly under the footing takes the greatest load, and therefore should be thoroughly compacted.

Because the load spreads out, the pressure on the soil is greatest right beneath the footing. By the time we get down below the footing a distance equal to the footings width, the unit soil pressure has dropped by about half. Go down the same distance again, and the pressure has dropped by two-thirds. So it's the soil right under the footing that is the most critical and also, typically, the most abused.
When we excavate for the footings, the teeth on the bucket stir up the soil and mix air into it, decreasing its density. Also, soil from the embankment may fall into the trench. Soil that loose has much less bearing capacity than the original soil. That's why it is so important to compact the trench bottom (use a vibrating plate compactor for sand or gravel soils, and a jumping jack compactor for silt or clay). If you don't compact that soil, you could get 1/2 inch of settlement in just the first 6 inches of soil.
If you dig too deep and replace the soil to recover the grade, you are adding back soil that has expanded by as much as 50%. Under load, it will reconsolidate and cause settling. So when you replace material in the trench, compact it thoroughly, or else use large gravel. One-inch-and-a-half or larger gravel is virtually self-compacting as you place it. Under the weight of a wood house, it won't settle to any significant degree.

Hope this help.

Marcel

[Kenton H. Shepard, CMI]

Originally Posted by dbucknavich

Does this somehow relate to a footing and range of support in the earth underneath said footing? You know, how you are not able to excavate within a 45 degree angle from the footing.

Yep, that's it.

[Kenton H. Shepard, CMI]

Originally Posted by ccurrins

Angle of Repose

That's it. I guess it means the same thing but that's what I was trying to remember, thanks Christopher!

There's been some nice houses wrecked or severely damaged by digging out the basement for increased headroom and interrupting the cone of compression. Good illustration, Marcel!

[Christopher Currins]

Originally Posted by kshepard

That's it. I guess it means the same thing but that's what I was trying to remember, thanks Christopher!

There's been some nice houses wrecked or severely damaged by digging out the basement for increased headroom and interrupting the cone of compression. Good illustration, Marcel!

Glad I could help, that's one thing I learned in my pre-licensing class.

[Bruce A. King]

Nope, thats not it, angle of repose and cone of compression are two different subjects.

The angle of repose is the natural angle that a given material settles to when piled up.

My previous post and Marcels is what you need.

[Kenton H. Shepard, CMI]

Bruce, according to what I found with google, "axial loading" and "axial compression" have to do with a load or compression being parallel to the long axis of a structure rather than with the load distribution profile in soil beneath foundations.
However you're right about the "angle of repose".

[Kenton H. Shepard, CMI]

Here's a successful attempt to dig out a crawlspace to create a basement. It does interrupt the cone of compression at 45 degrees but has been effective enough so that there was no evidence of failure after many years.