Deep Soil on Both Sides of the Retaining Wall

[The80sRock]

Have you ever written a simple word and then looked at it wondering if you spelled it right? And you just questioned it for a while until you had to look it up in a dictionary and know you had it right? I'm having one of those moments in regards to a retaining wall.

The wall retains 18' of soil on the back side with a 36" diameter RCP in the bottom center of the wall discharging water into a ditch on the front side. The pipe is not what's bothering me. The ditch on the front side is at it's lowest in the center of the wall. But as ditches tend to do, it slopes up to either end of the wall exposing less and less of the front side of the wall until there is only 2' of exposed wall at both ends. So at the ends of the wall I have 18' of retained soil and 16' of soil over the toe. In my mind, the wall is not doing much work at that point and just completely overdesigned, which the owner doesn't care about. This is everyone else's experience as well, correct? That much soil on the front side counteracts the rotation and sliding from the soil on the back side? I'm using you guys as my dictionary right now. What am I missing?

 

[phamENG]

True, but depending on the contractor, form work supplier, and plenty of other variables it could make sense to just design worst case and keep rolling. If the owner doesn't care, then why design 4 walls when you can design 1?

I did a similar project last month, but it was 11' high at the pipe invert. Thing is, the owner cared very much about every piece of aggregate, grain of sand, drop of water, etc. So I had to design 6 different wall heights to "optimize" the amount of material.

 

[MIStructE_IRE]

What are you missing..?

A sketch!

 

[GC_Hopi]

You could step the wall to work with the grading depending on how the Civil work is done. Sometimes it is just simpler to build when things are consistent. Look at the wall thickness in this photo. Could the wall be tapered, sure...