Load Path over Buried Pipe

[CSNuke]

I'm looking for some different ways to evaluate load paths of large vehicles and cranes over buried pipes & duct banks of varying size, depth and material. This includes both on pavement and bare soil. I have seen some examples but wanted to see if anyone had ones that worked well for them. Let me know if there is a method you use. Thanks.

 

[rconner]

I believe most authorities use approaches that are take-offs from Holl's or Newmarks's integrations of the Boussinesq formula for vertical unit pressure, at locations in the soil below the point of load application. Both approaches were depicted many years ago in
Merlin Spangler's textbook, "Soil Engineering". While I think Spangler probably intended Holl's approach, that assumes a "point" load at the surface, be used for most basic normal traffic (trucks etc.) loading on conduits, I have seen Newmark's also used, particularly when the footprints and loads are much larger on the surface. Of course with either I guess it is possible to superimpose effects of more than one location on the surface, and I think that also has been done in the past e.g. to determine effects of "passing trucks" on a highway or axle loadings etc. With either loading, it is probably appropriate to use an impact factor to at least try to account for dynamic effects. For most exotic loadings, I guess it is just about necessary to know something about the equipment involved. The largest live loading I can remember seeing is that of a Boeing 747 many years ago, though that has probably been surpassed by something else since!

 

[Ron]

I use elastic layer analysis. Have used this on a variety of different loadings (missile carriers, the Space Shuttle, various aircraft, buses, trucks and cranes).

While it can be done by hand, that usually limits the analysis to a couple of layers (you can do more, it's just tedious). There are numerous elastic layer analysis programs in the public domain (ChevPC, ELSYM5, EverStress, etc).

Check pavement textbooks such as Yang Huang's Pavement Analysis text or Yoder and Witczak's Principles of Pavement Design. Huang's book comes with an analysis program that's workable, though not particularly user friendly.

 

[BigInch]

Most of the pipeline guys still use Spangler, unless there is some very powerfull reason why you absolutely can't.

http://virtualpipeline.spaces.live.com