Pipe Deformation

I would like to know if there is any width variation at the small radius just above the bottom.

I surveyed one similar several years ago. It was a reinforced concrete pipe 72" in diameter (to begin with). I am only 5'-8" tall so I should have been able to walk upright down the invert from end to end. I had to duck several inches to be able to walk down the pipe. It should have been a Class 5 (Georgia DOT rating, and probably with imperfect backfill) under 40 feet of fill but the contractor installed a Class 3. We ended up sliding a steel spiral welded pipe through the deformed pipe and pumping grout into the voids. Some loss in capacity but the difference in friction loss mitigated the difference. The best design in the world doesn't work if the contractor doesn't install per the specs.

Andy

Here's a finished plan-profile.

and a close up on the plan view.

The width measurement was taken from side to side at the mid-line joint as seen in this pic.

At the point where water surface and the joint appear the same -7.9' wide on the 7.5' pipe. the joint was underwater.

Thanks Mr. File, I'm thinking two things, lack of compaction below the spring-line and not enough cover.;-)

Thanks for the update!

Chr.

Looking at the cross section there appears to be PLENTY of cover (35+ feet). Not enough compaction below the spring line perhaps, but I believe that CMP like that would need imperfect backfill at that depth of cover to transfer the loads and avoid crushing the pipe. Now I'm going to have to go dig up my old pipe manuals, I haven't looked at them in years.

Andy