Modeling Culverts

I ran a dam failure simulation for a small dam with a large pipe arch culvert/roadway directly downstream two ways.

First, I scaled off the widths at different elevations of the culvert, and modeled the culvert/road as a bridge. The water surface went over the road.

Second, I used an old Army Corp. of Engineers rating for the culvert/road and modeled the culvert/road as a dam. The water surfae did not go over the road.

Next, I pulled out my Handbook of Steel drainage and Highway Construction Products book from AISI, and looked at the discharge capacity of the culvert (a corrugated steel, 15'-4" x 9'-3") and found the AC of Engineers rating looked good.I tried CulvertMaster from Haestad, and got similiar results.

There is a quick dropoff below the culvert, so backwater should not be a problem.

The Question: Is there anything special I should do to model culverts vs. bridges? I do have the upstream x-section using storage to funnel the approach flow area already.

I run into a lot of these situations, and would like to have more confidence in the model output at small bridges.

Thanks-
Dan

Dear Dan Mattaini :

You need to remember that culverts have much more losses that bridges do. So, you can model culverts with DAMBRK by treating them as small bridges, but you need to then calibrate the model to correctly mimic the culvert.

You do need to enter an approach cross-section and an exit cross-section for culverts, just like you need to for bridges.

If you have any additional questions or need any further information, please contact me again.

Sincerely,

Chris E. Maeder, M.S.
Senior Technical Engineer
chris.maeder@bossintl.com