new concrete retaining wall / abutting existing rubble wall

[Ben29]

We had a series of (6) rowhomes burn down. There is now a 90' wide lot between the remaining rowhomes. My job is to design a ~90 foot long concrete retaining wall to separate the existing sidewalk from the monstrous "pit". We are retaining about 6ft of soil. The retaining wall design is easy enough.

The problem is that the new concrete retaining wall wants to abut (be in the same plane as) the existing front basement wall of the remaining house (which is vacant and probably condemned). I think the bottom of the rubble wall is at grade, or maybe 8" below grade at best. So I will undermine the rubble wall when we dig the footing for the retaining wall.

Another issue is how do I make the joint between the new and old walls?

 

[JoelTXCive]

Could you do some thing like this for the transition.

I'm not sure about the temp shoring. Could you post a plan view sketch?

 

[Ben29]

Joel: What you are showing in your sketch is exactly right. I actually had that same idea regarding the small 2-3ft wall return.

 

[Ben29]

 

[TRAK.Structural]

I would probably be looking to shotcrete the exposed portion of that existing basement wall, maybe with a mesh of #4 bars, just so it doesn't crumble during construction. I wouldn't make any hard connection of the new wall to the old.

I think your idea could work, but I wonder if you will start to lose soil material out from the bottom of the wall where the footing depth transition occurs. It's a little hard to visualize.