Overlapping stress bulbs/vertical stress at a known depth

[ac4u2nv]

Dear all
can anyone reccomend me some resources to learn how to calculate overlapping stress bulbs effects and the cumulative vertical stress.
textbooks website etc..
e.g if two wheels on a haul road, how will those combined loads affect a pipe in the ground.

thank you

 

[1503-44]

Generally assumed as two pyramids of a stress fields, peak originating at tire/ground surface area with pressure and contact area of the tire. Contact area = tire load/ tire pressure.

As the depth increases, the stress field area increases with the increasing area of the pyramid, it is the same wheel load, so stress reduces with depth. If pyramids intersect, the stresses in each pyramid at any given level are typically just added together.

Pyramid angle usually assumed at 45°. Stresses decrease rapidly with depth and usually minimum clear burial depths for highways of 4ft don't often affect steel pipe very much, unless you have an especially high tire load.

 

[ac4u2nv]

any references for this?
so if its the same load, then just double it at the point they intersect?

 

[GeoEnvGuy]

If your interested in buried pipe cover requirements. You can find design guidance on the plastic pipe organization website.

 

[fattdad]

there are equations in DM 7.01. Vulcanhammer has this document archived. Here's their link:

https://vulcanhammernet.files.wordpress.com/2017/01/dm7_01.pdf

If it's two loads, then use superposition. Calculate each then add together the results for the point of interest.

It'll take a spreadsheet and the stress equations in the book.

I take it you are considering vertical loads at depth. When using these horizontal equations, there are conditions, i.e., if considering retaining walls, where you need to double the results. Can't quite explain all that!

f-d

ípapß gordo ainÆt no madre flaca!

 

[1503-44]

Maybe you want API RP 1102 method.

 

[Ron]

Layered elastic analysis....check Huang or Yoder and Witzcak

 

[1503-44]

Pipelines seldom if ever get farther down then the first layer.
And there is too little room to get very fancy with the analysis. Not enough room to draw curves in place of straight lines.