RETAINING WALL FOUNDATION AT DIFFERENT LEVELS

[Tstruct]

Pease refer to the attached sketch.
I have retaining walls at different levels as shown in option "1" in the attachment. I don't want to transfer the pressure of the upper wall to the lower wall and keeping in view the constructability constraints, I can't go for option 1. In option 2 the bulky part of concrete to reach the desired level of foundation seems too inappropriate for such a small retaining wall. Also I am unable to find any source to determine the dimensions I mentioned with question mark in option 2. I need your opinions on how to deal with this situation.

 

[dflva]

The change in elevation shown in Option 1 is too large for a single step. Step the foundation down using two or three steps along the length of the wall.

 

[HTURKAK]

Consider the following dimensions . The higher level found. will be constructed first.

EDIT : You may use blinding conc. for plain concrete fill. ( Lean conc. (1.4.8 is OK)
...

He is like a man building a house, who dug deep and laid the foundation on the rock. And when the flood arose, the stream beat vehemently against that house, and could not shake it, for it was founded on the rock..

Luke 6:48

 

[Tstruct]

@Hturkak I would like to know what factors/criteria to consider to proportion such shapes? We usually have to deal with such foundation shapes in other structures too, but all I have seen is "practices" being followed. Can I use lean concrete (1:4:8) here?
@dflva that could be an option too, but still I would need some reference for proportioning.

 

[JoelTXCive]

TxDOT has a detail for a retaining wall step that they have used for at least 10 years. It super simple. They just use a "Z-Bar"

I'm comfortable using this detail for a for a 3ft elevation difference.

I would not be surprised if the other big states DOT's have a similar detail. Check California and Florida.

 

[JoelTXCive]

Here's a step that I did a few years ago. I used the TxDOT detail as my starting point. I decided to put an expansion joint right at the step so that if the walls wanted to move a little bit independently, then they could. (My elevation change was 8ft)