Retaining Wall - Fixing Contractor screw up 2

[Bhotar3]

Client is building 11'-0" retaining wall (attached) at his property. Contractor pours footing, but instead of installing the dowels according to drawing (#8s 8" O.C. 5'-0" dev. length ), He installs #5s with only 2'-0" development. Vertical portion has not yet been installed.

Assuming the #5s will not work (i've not yet run the numbers), what are my options here?

Is there a post-install dowel solution that would resist the moment at the base of the wall? I also thought about helical tie-backs.

I appreciate any feedback.

 

[SJBombero]

Counterforts on the back of the wall.

 

[SwinnyGG]

With 17" of available concrete embedment depth, I would suspect there's potential for a drill & epoxy solution that provides enough pullout. If you can handle them being 4" OC.

 

[STrctPono]

Although I'm not a big fan of that detail utilizing the center #8 dowel with a non-contact lap splice with the back face reinforcing it technically will work.

Running through a few numbers...

Moment demand at base of stem: 1.6*40x11^2*(1/2)*(11/3) = 14.2k-ft/ft

Moment capacity at base of stem (w/ #8 dowels): 0.9*1.185*60*(8-(2.32/2)) = 437k-in/ft or 36.5k-ft/ft

Moment capacity at base of stem (w/ #5 dowels installed): 0.9*0.465*60*(8-(0.912/2)) = 190k-in/ft or 15.8k-ft/ft

Either way, I don't like the 2'-0" embedment for the non-contact lap and the Contractor should have to pay a disobedience penalty. You can develop a #6 bar in a 15" deep post-installed hole in 3ksi concrete. Have them drill and epoxy between the existing dowels (@8" o.c.) but on the backside face of the wall (in line with the vertical reinforcing). Check to make sure they clean their holes properly or it's all for nothing.

 

[Bhotar3]

Appreciate the feedback. Would you have the post installed #6 embedment be the original 5’-0” ?

Also: I believe I follow your last 2 equations. Can you explain the first? Thanks!

 

[STrctPono]

Bhotar3. This is how I rationalize the height of your center bar. Based on your parameters, yes, I believe 5'-0" would just be enough.

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1636675310/tips/SKM_C55821111113580_flgxpm.pdf[/url]

I was calculating the overturning moment due to earth pressure at base of wall stem... Assuming active earth pressure, 30 degree friction angle, 120lbs/ft3 unit weight of soil, and stem wall height of 11ft.

40pcf active earth pressure
1.6 Gamma Factor
11'-0" wall stem height

 

[JoelTXCive]

What is the wall length?

If it's a short wall, it might be easier to demo it and start over.

 

[STrctPono]

SJBombero's suggestion is good too if you really want to stick it to the contractor but I believe it can be done without requiring that much work. If you do go with counterforts, remember that this changes the behavior of your front and back face horizontal reinforcing so you would need to check this to ensure that you have enough for the stem to span horizontally between the buttresses. Additionally, this wall will probably be stiff enough that you should employ at-rest earth pressures.