Drainage pipe - Railroad Liveloads

[qaztor]

I have already determined that the liveloads over a drainage pipe (part of bridge drainage) that crosses a railroad is approx. 19psi.

The pipe I want to use is a 6in. or 8in. PVC SDR18. This might be very simple but how do I determine if this pipe can withstand the load?

Thanks

 

[cub3bead]

Are you sure that the RR will let you get by without using a steel sleeve to run the PVC pipe through?

 

[dicksewerrat]

there is a formula 'Spanglers' I think. Anyway it is in the ASTM F1216 for the deflection of a flexible pipe. Put your values in there and if deflection is over 5%, the pipe is in failure. Also like cub3bead stated, check with the railroad first. They usually have very strict ciriteria for pipes under tracks.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[qaztor]

Thanks for your comments. The bridge where we are doing the improvements is actually a railroad bridge... no problems there.

Now, I also found that ASTM through various product standards has recommended a Maximum Allowable Deflection Limit of 7.5%.
To find the deflection and the loads imposed on the pipe at different depths, I downloaded from UNI-BELL.ORG the software:

"external load design for uni-bell flexible conduits."

Great tool to compare your hand made calculations.

I hope this helps

RC

 

[stanier]

Suggest you download AS 2566 Australian Standard for Buried Flexible Pipelines from

http://www.standards.com.au.

It is moderate cost but is a world leader in such designs.

Books you may also consider are Buried Pipe Design by Moser or Structural Mechanics of Buried Pipelines. I am sure AWWA have similar design standards however AS 2566 is very comprehensive as a design standard and guide.

What you are looking at is a combined soil/pipe structure. Many railway organisations will insist on a sleeve. Beware if the railway is electrified stray currents could cause the failure of the steel inside 6 months. You may need to electrically isolated with a good coating.

The GAS Research Institute/Cornell University did a great deal of study. Their final report "Technical Summary and Database for Guidelines for Pipeline Crossings Railroads and Highways GRI-91/0285 is definitely worth the investment.