How to attach concrete buttress wall to toe side face of CMU retaining wall?

[MAEngr]

How do you guys recommend attaching a concrete buttress wall spaced a certain distance attached to the toe side open face of a CMU retaining wall? Would it be as simple as dowel and epoxy into the cmu wall with your horizontal buttress wall bars or to attach angles to the corners where the two walls meet and use titen bolts? Or other recommendations? The cmu wall blocks are 8” wide.

The buttresses will be on a steeper hillside so the footings for them will also be significantly lower than the cmu retaining walls footing.

 

[driftLimiter]

Sketch please. and Loading information if applicable.

 

[KootK]

Drill and adhesive works for me in general. The steel just sounds like needles corrosion item to me. I assume the CMU is solid grouted.

I don't love the sound of trying to construct the buttresses on a steep, toe side slop but maybe it will check out once I see your cross section. Feels like a dirt side reinforcement scheme might be easier.

 

[MAEngr]

Here is an elevation view and a section view. the sketches aren't complete but show applicable info. The contractor is pretty adamant about not wanting to excavate on the heel side. I like this solution the least, but they want to price it.

Right now i am using code minimum soil values in arizona, we will have a geotech if this repair rec is picked. The CMU is solid grouted, so should i spec the horizontal bars to extend 6" beyond the buttress so that they can dowel and epoxy into the face of the cmu wall?

More context is this was was constructed to a 6' prescriptive design, but final construction has this wall at 8' of backfill so it is stressed and bowing 1-2". The buttress is to help alleviate the stress by providing intermediate support for the wall.

 

[XR250]

Probably should have just continued your earlier post. I assume it is the same 60 ft. long retaining wall?
This repair looks like a total CF. What happened to the tie-back idea? Seems a lot cheaper.

 

[MAEngr]

It is XR250, you're right. ill add on to my thread there instead of here.

The contractor is doing everything he can to not excavate behind the wall. I told him of the difficulties of this approach and we are working on getting price quotes for other alternative repairs. but he is really trying to push for this buttress repair.

 

[XR250]

It is XR250, you're right. ill add on to my thread there instead of here.

The contractor is doing everything he can to not excavate behind the wall. I told him of the difficulties of this approach and we are working on getting price quotes for other alternative repairs. but he is really trying to push for this buttress repair.

Helical tiebacks do not require excavation behind the wall.

 

[MAEngr]

They’re not required to excavate behind the wall, but it seems like it could be beneficial to since it could help with unbowing the wall and also reduces the required hole you have to drill through the wall which considering the weakened state of the wall would be a benefit. It doesn’t seem like the contractor wants to proceed with that option either way, but it is proposed.