Vibratory Roller Impact on Burried Utility Pipes 1

[HeatherMae]

Hello all,
I am working on a project where we are building up the soil deth over top of a lot of buried utilities. We are adding about 2 feet of compacted soil. THe existing depths of the utilies (sanitary, water, gas) are between 16 and 20 feet. Our client wants some type of calculation done to show that the vibrations from the compacttion equipment wont damage the pipes. Intuitively I am thinking that since they are buried so deep that it won't be an issue, but I still need to provide proof to the client.

I am looking for anyone who can point me to the right reference or formula regardingthis topic.
THhanks,
Heather

I am a structural engnieer, so my experience with pure geotechnical engineering is limited.

 

[Ron]

If soil in the trench has been properly compacted, vibratory compaction has little effect on the pipe. A compactor typically will affect the soil to a depth about equal to the drum diameter. You can get dynamic info from the compactor manufacturer. Caterpillar has some good data, as does Bomag.

You can compute the stress state at the top of the pipe by elastic layer analysis, such as you would use for pavements. Check Yang Huang's book on Pavement Design or Yoder and Witczak's book on Pavement Design. Both provide a method to hand-calculate a two-layer elastic layer and determine the stresses at any level due to a load on the surface.

If you have capability and are familiar with elastic layer analysis, you can use one of several elastic layer programs to compute stresses at the top of the pipe. One good program that is in the public domain is available from the Washington Department of Transportation. It is called EverStress. Others, though a bit harder to find are ELSYM5 and ChevPC. Both of these will handle up to 5 layers.